AIR CONDITIONER, CONTROL METHOD FOR AIR CONDITIONER, AND INDOOR UNIT

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of International Application No. PCT/KR2025/015825 designating the United States, filed on Oct. 2, 2025, in the Korean Intellectual Property Receiving Office and claiming priority to Korean Patent Application No. 10-2024-0143268, filed on Oct. 18, 2024, in the Korean Intellectual Property Office, the disclosures of each of which are incorporated by reference herein in their entireties.

BACKGROUND

Field

The disclosure relates to an air conditioner, a control method for the air conditioner, an indoor unit included in the air conditioner, and a computer-readable recording medium having recorded thereon a program for executing, on a computer, the control method for the air conditioner.

Description of Related Art

A multi-system air conditioner known as a system air conditioner includes one or more outdoor units and two or more indoor units, and may perform central control type air conditioning for an entire building or one or more floors of a building.

The multi-system air conditioner may control the two or more indoor units to operate in different operating modes (e.g., a cooling operation and a heating operation) simultaneously. The multi-system air conditioner may switch between the cooling operation and the heating operation of each indoor unit.

When a transfer valve is suddenly opened in the multi-system air conditioner to switch the operating mode, noise and vibration may occur in the air conditioner or a refrigerant pipe may be damaged as a refrigerant in a high-pressure section flows to a low-pressure section. In this regard, a control method for reducing a refrigerant pressure difference that occurs while switching between the operating modes has been developed.

Also, even if control for reducing the refrigerant pressure difference is performed, the refrigerant pressure difference may not be normally reduced when a valve included in the air conditioner malfunctions or a control error occurs. When the operating mode is changed without reducing the refrigerant pressure difference, noise and vibration may still occur in the air conditioner, and the refrigerant pipe may still be damaged.

SUMMARY

A control method, according to an example embodiment of the disclosure, for an air conditioner including an outdoor unit, a plurality of indoor units connected to the outdoor unit, and a mode change control device comprising at least one valve connecting the outdoor unit to the plurality of indoor units and configured to switch between a cooling operation and a heating operation of each of the plurality of indoor units, the control method including: performing a first operation corresponding to one of a cooling operation or a heating operation, stopping the first operation based on a switch command to switch from the first operation to a second operation corresponding to the other one of the cooling operation or the heating operation, while the first operation is stopped, performing pressure equalization control to reduce a refrigerant pressure difference of opposite sides of a transfer valve for the second operation, determining whether the refrigerant pressure difference has been reduced based on the pressure equalization control, and based on a result of the determination, determining whether to perform the second operation.

An air conditioner according to an example embodiment of the disclosure includes: an outdoor unit, a plurality of indoor units connected to the outdoor unit, a mode change control device comprising at least one valve connecting the outdoor unit to the plurality of indoor units and configured to switch between a cooling operation and a heating operation of each of the plurality of indoor units, a memory including at least one storage medium storing one or more instructions, and at least one processor comprising processing circuitry, wherein at least one processor is individually or collectively is configured to execute the one of more instructions and to cause the air conditioner to: perform a first operation corresponding to one of a cooling operation or a heating operation; stop the first operation based on a switch command to switch from the first operation to a second operation corresponding to the other one of the cooling operation or the heating operation; while the first operation is stopped, perform pressure equalization control to reduce a refrigerant pressure difference of opposite sides of a transfer valve for the second operation; determine whether the refrigerant pressure difference has been reduced based on the pressure equalization; and determine whether to perform the second operation based on a result of the determination.

An indoor unit, according to an example embodiment of the disclosure, connected to an outdoor unit and a mode change control device comprising a valve, includes: an indoor heat exchanger, an indoor electronic expansion valve (EEV), an indoor unit communicator comprising communication circuitry, a memory including at least one storage medium storing one or more instructions, and at least one processor comprising processing circuitry, wherein at least one processor, individually or collectively, is configured to execute the one or more instruction and to cause the indoor unit to: perform a first operation corresponding to one of a cooling operation or a heating operation by opening the indoor EEV, obtain a switch command to switch from the first operation to a second operation corresponding to the other one of the cooling operation or the heating operation, stop the first operation by controlling the indoor EEV to be closed, based on the switch command, transmit a control signal corresponding to the switch command to the outdoor unit and the mode change control device through the indoor unit communicator, determine whether a refrigerant pressure difference of opposite sides of a transfer valve for the second operation has been reduced, while the first operation is stopped, and determine whether to perform the second operation by opening the indoor EEV, based on a result of the determination.

A non-transitory computer-readable recording medium according to an example embodiment of the disclosure has recorded thereon a program for executing, on a computer, the control method for an air conditioner.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other aspects, features and advantages of certain embodiments of the present disclosure will be more apparent from the following detailed description, taken in conjunction with the accompanying drawings, in which:

FIG. 1 is a diagram illustrating an example configuration of an air conditioner, according to various embodiments.

FIG. 2A is a block diagram illustrating various components connected to a refrigerant pipe of an air conditioner, according to various embodiments.

FIG. 2B is a diagram illustrating example flow of a refrigerant according to a cooling operation and a heating operation of an air conditioner, according to various embodiments.

FIG. 3 is a diagram illustrating flow of a refrigerant in a mode change control device and a plurality of indoor units of an air conditioner, according to various embodiments.

FIG. 4A is a diagram for illustrating an example process in which an air conditioner switches from a cooling operation to a heating operation, according to various embodiments.

FIG. 4B is a table illustrating a valve operation when the air conditioner of FIG. 4A switches from the cooling operation to the heating operation according to various embodiments.

FIG. 5A is a diagram for illustrating an example process in which an air conditioner switches from a heating operation to a cooling operation, according to various embodiments.

FIG. 5B is a table illustrating a valve operation when the air conditioner of FIG. 5A switches from the heating operation to the cooling operation according to various embodiments.

FIG. 6A is a diagram illustrating an example process in which an air conditioner switches from a cooling operation to a heating operation, according to various embodiments.

FIG. 6B is a table illustrating a valve operation when the air conditioner of FIG. 6A switches from the cooling operation to the heating operation according to various embodiments.

FIG. 7A is a diagram illustrating an example process in which an air conditioner switches from a cooling operation to a heating operation, according to various embodiments.

FIG. 7B is a table illustrating a valve operation when the air conditioner of FIG. 7A switches from the cooling operation to the heating operation according to various embodiments.

FIG. 8A is a diagram illustrating an example process in which an air conditioner switches from a cooling operation to a heating operation, according to various embodiments.

FIG. 8B is a table illustrating a valve operation when the air conditioner of FIG. 8A switches from the cooling operation to the heating operation according to various embodiments.

FIG. 9A is a diagram illustrating an example process in which an air conditioner switches from a cooling operation to a heating operation, according to various embodiments.

FIG. 9B is a table illustrating a valve operation when the air conditioner of FIG. 9A switches from the cooling operation to the heating operation according to various embodiments.

FIG. 10 is a block diagram illustrating an example configuration of an indoor unit, a mode change control device, and an outdoor unit, according to various embodiments.

FIG. 11 is a flowchart illustrating an example method of detecting a pressure equalization control error when switching an operating mode of an air conditioner, according to various embodiments.

FIG. 12 is a signal flow diagram illustrating an example method of detecting a pressure equalization control error when an air conditioner switches from a cooling operation to a heating operation, according to various embodiments.

FIG. 13 is a signal flow diagram illustrating an example method of detecting a pressure equalization control error when an air conditioner switches from a heating operation to a cooling operation, according to various embodiments.

FIG. 14 is a diagram illustrating an example operation in which an air conditioner obtains an operating mode switch command, according to various embodiments.

FIG. 15 is a flowchart illustrating an example method of detecting a pressure equalization control error when switching an operating mode of an air conditioner, according to various embodiments.

FIG. 16 is a block diagram illustrating an example configuration of an air conditioner according to various embodiments.

DETAILED DESCRIPTION

It should be understood that the various example embodiments of the disclosure and the terms used herein are not intended to limit the technical features described in the disclosure to specific embodiments of the disclosure, and include various modifications, equivalents, or alternatives of corresponding embodiments of the disclosure.

In relation to the description of drawings, like reference numerals may denote like or related elements.

The singular form of a noun corresponding to an item may include one or more of items, unless the context clearly indicates otherwise.

In the disclosure, each of the phrases “A or B”, “at least one of A and B”, “at least one of A or B”, “A, B, or C”, “at least one of A, B, and C”, and “at least one of A, B, or C” may include one of the items listed together in the phrase or all possible combinations of the items.

The term “and/or” includes a combination of a plurality of related components or one component from among the plurality of related components.

The terms such as “first” and “second” may be used to distinguish one component from another component, and do not limit the components in another aspect (e.g., importance or order).

When a component (e.g., a first component) is referred to as being “coupled” or “connected” to another component (e.g., a second component), with or without the term “functionally” or “communicably,” the component may be connected to the other component directly (e.g., wired), wirelessly, or through a third component.

The terms such as “including” or “having”, etc., are intended to indicate the existence of the features, numbers, steps, actions, components, parts, or combinations thereof described in the disclosure, and are not intended to preclude the possibility that one or more other features, numbers, steps, actions, components, parts, or combinations thereof may exist or may be added.

When a component is “connected,” “coupled,” “supported,” or “in contact with” another component, not only the components are directly connected, coupled, supported, or in contact with each other, but also the components are indirectly connected, coupled, supported, or in contact with each other through a third component.

When a component is “on” another component, not only the component is in contact with the other component, but also an intervening component may be present between the two components.

In the disclosure, a “processor” may include various processing circuits and/or a plurality of processors. For example, the term “processor” used herein including claims may include at least one processor and thus may include various processing circuits. In the at least one processor, one or more processors may be configured to perform various functions described herein, either individually or collectively, in a distributed fashion. As used herein, a “processor”, “at least one processor”, or “one or more processors” may be configured to perform several functions. Such terms unlimitedly cover a situation where one processor may perform some of functions and another processor (other processors) may perform another some of the functions, and a situation where a single processor may perform all functions. Also, at least one processor may include a combination of processors configured to perform various functions in a distributed manner. At least one processor may be configured to execute program instructions to achieve or perform various functions.

In the disclosure, the term “user” denotes a person who controls a system, a function, or an operation, and may include a developer, a manager, an installation engineer, or a service engineer.

Hereinafter, an air conditioner according to various embodiments of the disclosure will be described in greater detail with reference to the drawings.

FIG. 1 is a diagram illustrating an example configuration of an air conditioner, according to various embodiments. FIG. 2A is a diagram for illustrating various components connected to a refrigerant pipe of an air conditioner, according to various embodiments. Components of an air conditioner 1000 according to an embodiment of the disclosure will be described with reference to FIGS. 1 and 2A.

The air conditioner 1000 according to an embodiment of the disclosure may refer to an apparatus configured to perform functions, such as air purification, ventilation, humidity control, cooling, and heating, in an air-conditioned space, and denotes an apparatus including at least one of the functions. The air conditioner 1000 may be implemented in the form of a cooler, a heater, a cooler/heater, an air purifier, a dehumidifier, etc.

The air conditioner 1000 according to an embodiment of the disclosure may include an outdoor unit 100, a plurality of indoor units 200-1, 200-2, . . . , and 200-n, and a mode change control device 300. The outdoor unit 100 may be provided in an outdoor space and perform heat exchange between outdoor air and a refrigerant. The plurality of indoor units 200-1, 200-2, . . . , and 200-n may be provided in an indoor space and perform heat exchange between indoor air and the refrigerant. The mode change control device 300 may distribute the refrigerant supplied from the outdoor unit 100 to the plurality of indoor units 200-1, 200-2, . . . , and 200-n to selectively perform cooling or heating. The outdoor unit 100, the plurality of indoor units 200-1, 200-2, . . . , and 200-n, and the mode change control device 300 may be connected to each other through a refrigerant pipe. In the disclosure, each of the plurality of indoor units 200-1, 200-2, . . . , and 200-n may be referred to as an indoor unit 200.

Referring to FIG. 2A, the outdoor unit 100 may include a compressor 110 configured to compress the refrigerant, and an outdoor heat exchanger 120 configured to perform the heat exchange between the outdoor air and the refrigerant.

The plurality of indoor units 200-1, 200-2, . . . , and 200-n may include indoor heat exchangers 210-1, 210-2, . . . , and 210-n (210) configured to perform the heat exchange between the indoor air and the refrigerant, and indoor electronic expansion valves (EEVs) 220-1, 220-2, . . . , and 220-n (220) configured to decompress the refrigerant provided to the indoor heat exchanger 210 during cooling, respectively.

An EEV may adjust an opening degree (e.g., the degree to which a valve is opened) to control the amount of refrigerant passing through the EEV or control the pressure of refrigerant. When an opening degree is expressed from 0% to 100%, the opening degree 0% may indicate a completely closed state of a valve and the opening degree 100% may indicate a completely open state of the valve. A minimum opening degree may denote a state in which an EEV is opened to the least and has a defined opening degree greater than the opening degree 0%. When the EEV is opened to the minimum opening degree, the EEV may be used as an expansion device configured to increase a refrigerant pressure difference of opposite sides of the EEV. A maximum opening degree may denote a state in which the EEV is opened to the most and correspond to the opening degree 100%, but is not limited thereto. When the EEV is opened to the maximum opening degree, the refrigerant freely passes through the EEV, and thus, the refrigerant pressure difference of the opposite sides of the EEV may be decreased. The EEV may also be referred to as an electronic expansion valve, an electric variable valve, or an electronic valve.

The mode change control device 300 may be provided between the outdoor unit 100 and the indoor unit 200 and transmit the refrigerant provided from the outdoor unit 100 to the refrigerant pipe of each of the plurality of indoor units 200-1, 200-2, . . . , and 200-n. For example, the mode change control device 300 may selectively transmit, to each of the plurality of indoor units 200-1, 200-2, . . . , and 200-n, a liquid refrigerant or a high-pressure gas refrigerant transmitted from the outdoor unit 100. The mode change control device 300 may control the plurality of indoor units 200-1, 200-2, . . . , and 200-n to operate in different modes simultaneously.

The mode change control device 300 may switch between a cooling operation and a heating operation of the indoor unit 200. The mode change control device 300 may also be referred to as a distributor or a mode change unit (MCU) configured to control a switch between the cooling operation and the heating operation.

The mode change control device 300 may be provided inside the refrigerant pipe and include a transfer valve configured to control a flow of the refrigerant according to an operating mode of the air conditioner 1000, e.g., the heating operation and the cooling operation. For example, the transfer valve may include a heating valve and a cooling valve. Each of the heating valve and the cooling valve may be provided in plural according to the number of indoor units included in the air conditioner 1000. For example, the mode change control device 300 may include a plurality of heating valves 310-1, 310-2, . . . , and 310-n (310) and a plurality of cooling valves 320-1, 320-2, . . . , and 320-n (320). The mode change control device 300 may change a direction in which the refrigerant flows by opening one of the heating valve and the cooling valve provided according to each indoor unit and closing the other one, according to an operating mode of each indoor unit.

The outdoor unit 100 and the mode change control device 300 may be connected to each other through a high-pressure gas pipe, a low-pressure gas pipe, and a liquid pipe. The mode change control device 300 and the plurality of indoor units 200-1, 200-2, . . . , and 200-n may be connected to each other through a refrigerant pipe corresponding to a high-pressure gas pipe or a low-pressure gas pipe, and a liquid pipe.

FIG. 2B is a diagram for illustrating example flow of a refrigerant according to a cooling operation and a heating operation of an air conditioner, according to various embodiments. For convenience of description, details that overlap those described with reference to FIGS. 1 and 2A may not be repeated here. In FIG. 2B, it is assumed that the heating valve 310 may correspond to one of the plurality of heating valves 310-1, 310-2, . . . , and 310-n, the cooling valve 320 may correspond to one of the plurality of cooling valves 320-1, 320-2, . . . , and 320-n, the indoor unit 200 may correspond to one of the plurality of indoor units 200-1, 200-2, . . . , and 200-n, the indoor heat exchanger 210 may correspond to one of the indoor heat exchangers 210-1, 210-2, . . . , and 210-n, and the indoor EEV 220 may correspond to one of the indoor EEVs 220-1, 220-2, . . . , and 220-n.

Referring to a cooling operation 201 of FIG. 2B, during the cooling operation 201 of the indoor unit 200, the cooling valve 320 may be in an open state and the heating valve 310 may be in a closed state. A refrigerant in a high-pressure liquid state transmitted through a liquid pipe 316 may pass through the indoor EEV 220 to become the refrigerant in a low-pressure liquid state, then perform heat exchange in the indoor heat exchanger 210, and then become the refrigerant in a low-pressure gas state. The refrigerant in the low-pressure gas state may pass through the cooling valve 320 and exit to a low-pressure gas pipe 314. The refrigerant in the low-pressure gas state may be transmitted to the outdoor unit 100.

The indoor heat exchanger 210 may perform heat exchange between the refrigerant and the air using a phase change (e.g., evaporation) of the refrigerant. For example, the refrigerant may absorb heat from the air while the refrigerant in the low-pressure liquid state, flowing through the indoor heat exchanger 210, is evaporated. An indoor space may be cooled down when the air that has been cooled down through the cooled indoor heat exchanger 210 is blown. The indoor heat exchanger 210 may receive a low-temperature low-pressure liquid refrigerant from the outdoor unit 100 and discharge a low-pressure gas refrigerant to the mode change control device 300 through heat exchange.

Referring to a heating operation 202 of FIG. 2B, during the heating operation 202 of the indoor unit 200, the heating valve 310 may be in an open state and the cooling valve 320 may be in a closed state. A refrigerant in a high-pressure gas state transmitted through a high-pressure gas pipe 311 may pass through the heating valve 310, then perform heat exchange in the indoor heat exchanger 210, and then exit as a high-pressure liquid refrigerant and pass through the indoor EEV 220. A refrigerant in a low-pressure liquid state, which passed through the indoor EEV 220, may be transmitted to the outdoor unit 100 through the liquid pipe 316.

The indoor heat exchanger 210 may perform heat exchange between the refrigerant and the air using a phase change (e.g., condensation) of the refrigerant. For example, the refrigerant may emit heat to the air while the refrigerant in the high-pressure gas state is condensed in the indoor heat exchanger 210. A space may be heated when the air that has been heated through the high-temperature indoor heat exchanger 210 is blown. The indoor heat exchanger 210 may receive a high-temperature high-pressure gas refrigerant from the outdoor unit 100 and the mode change control device 300, and discharge a high-pressure liquid refrigerant to the indoor EEV 220 through heat exchange.

The air conditioner 1000 may switch between the cooling operation 201 and the heating operation 202 of the indoor unit 200 through the mode change control device 300. For example, while one of the heating valve 310 and the cooling valve 320 is opened, the air conditioner 1000 may stop operation of the indoor unit 200 for an operating mode switch, and open the other one of the heating valve 310 and the cooling valve 320.

In this case, during the operating mode switch, a refrigerant pressure difference of opposite sides of a transfer valve (e.g., the heating valve 310 and the cooling valve 320) may be large. When the transfer valve is suddenly opened, a refrigerant in a high-pressure section may flow to a low-pressure section, causing significant noise and vibration in the indoor unit 200 and the mode change control device 300. Also, in severe cases, a pipe structure may be damaged. The air conditioner 1000 according to an embodiment of the disclosure may perform pressure equalization control to equalize pressure on the opposite sides of the transfer valve during the operating mode switch. The air conditioner 1000 may use a pressure equalization EEV for the pressure equalization control. The pressure equalization EEV may adjust an opening degree to control refrigerant pressure such that a pressure difference between the high-pressure section and the low-pressure section is decreased. Accordingly, even if the transfer valve is opened for a next refrigerant cycle, refrigerant flow noise and vibration may be significantly decreased.

For example, when the cooling valve 320 is in an open state and the heating valve 310 is in a closed state for the cooling operation 201 of the indoor unit 200, opposite sides of the closed heating valve 310 may respectively form the high-pressure section and the low-pressure section. In other words, the high-pressure gas pipe 311 connected to a first side of the heating valve 310 (e.g., a side at the outdoor unit 100) may be the high-pressure section, and a refrigerant pipe 312 connected to a second side of the heating valve 310 (e.g., a side at the indoor unit 200) may be the low-pressure section. In this case, when the heating valve 310 is suddenly opened for the heating operation 202, the refrigerant in the high-pressure section may flow to the low-pressure section, causing noise. However, according to an embodiment of the disclosure, when the pressure equalization EEV is controlled while operation is stopped, refrigerant pressure in the low-pressure section may be increased, and thus, the pressure difference between the high-pressure section and the low-pressure section may be decreased. When the pressure difference between the high-pressure section and the low-pressure section is decreased as such, even if the heating valve 310 is opened for the heating operation 202, a rapid flow of the refrigerant does not occur, and thus, refrigerant flow noise may be decreased. In the disclosure, the first side of the heating valve 310 is illustrated as the side at the outdoor unit 100, and the second side of the heating valve 310 is illustrated as the side at the indoor unit 200.

For example, when the heating valve 310 is in an open state and the cooling valve 320 is in a closed state for the heating operation 202 of the indoor unit 200, opposite sides of the closed cooling valve 320 may respectively form the high-pressure section and the low-pressure section. In other words, the low-pressure gas pipe 314 connected to the first side of the cooling valve 320 (e.g., the side at the outdoor unit 100) may be the low-pressure section, and the refrigerant pipe 312 connected to the second side of the cooling valve 320 (e.g., the side at the indoor unit 200) may be the high-pressure section. In this case, when the cooling valve 320 is suddenly opened for the cooling operation 201, the refrigerant in the high-pressure section may flow to the low-pressure section, causing noise. However, according to an embodiment of the disclosure, when the pressure equalization EEV is controlled while operation is stopped, refrigerant pressure in the high-pressure section may be decreased, and thus, the pressure difference between the high-pressure section and the low-pressure section may be decreased. When the pressure difference between the high-pressure section and the low-pressure section is decreased as such, even if the cooling valve 320 is opened for the cooling operation 201, a rapid flow of the refrigerant does not occur, and thus, refrigerant flow noise may be decreased. In the disclosure, the first side of the cooling valve 320 is illustrated as the side at the outdoor unit 100, and the second side of the cooling valve 320 is illustrated as the side at the indoor unit 200.

For example, the air conditioner 1000 may perform control of increasing a pressure of a refrigerant after performing a cooling operation and before the refrigerant in a high-pressure gas state, used for a heating operation, is introduced. In other words, the air conditioner 1000 may highly pressurize the refrigerant in a low-pressure section before switching from the cooling operation to the heating operation. For example, the air conditioner 1000 may perform control of decreasing the pressure of the refrigerant after performing the heating operation and before the refrigerant in a low-pressure gas state, used for the cooling operation, is introduced. In other words, the air conditioner 1000 may lowly pressurize the refrigerant in a high-pressure section before switching from the heating operation to the cooling operation.

Hereinafter, operations in which the air conditioner 1000 according to an embodiment of the disclosure reduces a pressure difference between a high-pressure section and a low-pressure section using various types of pressure equalization EEV will be described in greater detail below with reference to FIGS. 4A to 9A. For example, the pressure equalization EEV may include at least one of the indoor EEV 220 of FIG. 4A, a cooling sub valve 430 of FIG. 5A, a heating EEV 610 of FIG. 6A, a cooling EEV 620 of FIG. 7A, a heating sub valve 830 of FIG. 8A, or a cooling sub valve 840 of FIG. 9A. This will be described in greater detail below with reference to each drawing.

Operations in which the air conditioner 1000 according to an embodiment of the disclosure detects whether pressure equalization has been successfully performed before switching an operating mode will be described in greater detail below with reference to FIGS. 11 to 15. When a malfunction, such as a foreign matter being caught in an EEV type valve, occurs while the air conditioner 1000 performs pressure equalization control, pressure equalization may not be normally performed. When the transfer valve is opened while a pressure difference of opposite sides of the transfer valve is not reduced, noise and vibration may be still significantly generated in the indoor unit 200 and the mode change control device 300. For example, when it is determined that a temperature of an indoor heat exchanger has not reached a defined level even after the pressure equalization control is completed, the air conditioner 1000 may control operation to stop and display an error code. The air conditioner 1000 may switch the operating mode only when the temperature of the indoor heat exchanger has reached the defined level after the pressure equalization control is completed. Accordingly, the air conditioner 1000 may prevent and/or reduce refrigerant flow noise and vibration that may occur when the operating mode is switched.

Hereinafter, the air conditioner 1000 including a mode change control device 300a, according to an embodiment of the disclosure, will be described in greater detail with reference to FIGS. 3 to 5B.

FIG. 3 is a diagram illustrating flow of a refrigerant in a mode change control device and a plurality of indoor units of an air conditioner, according to various embodiments.

Referring to FIG. 3, for convenience of description, details that overlap those described with reference to FIGS. 1 to 2B may not be repeated here. The air conditioner 1000 according to an embodiment of the disclosure may include the outdoor unit 100, the plurality of indoor units 200-1, 200-2, . . . , and 200-n, and the mode change control device 300a. The mode change control device 300a may include heating main valves 410-1, 410-2, . . . , and 410-n (410 of FIG. 4A), cooling main valves 420-1, 420-2, . . . , and 420-n (420 of FIG. 4A), and cooling sub valves 430-1, 430-2, . . . , and 430-n (430 of FIG. 4A). Each of the plurality of indoor units 200-1, 200-2, . . . , 200-n may be connected to refrigerant pipes 312-1, 312-2, . . . , 312-n and liquid pipes 316-1, 316-2, . . . , 316-n. The mode change control device 300a of FIG. 3 may correspond to the mode change control device 300 of FIGS. 1 to 2B. The heating main valve 410 of FIG. 3 may correspond to the heating valve 310 of FIG. 2A. The cooling main valve 420 of FIG. 3 may correspond to the cooling valve 320 of FIG. 2A. Compared to the mode change control device 300 of FIGS. 1 to 2B, the mode change control device 300a of FIG. 3 may further include the cooling sub valve 430.

The heating main valve 410 and the cooling main valve 420 according to an embodiment of the disclosure may each be a solenoid type valve. The solenoid type valve may control closing/opening of a valve using an electromagnetic coil (e.g., a solenoid), and completely open or completely close a fluid flow of a specific section through on control or off control. However, the disclosure is not limited thereto, and the heating main valve 410 and the cooling main valve 420 may each be an EEV valve for controlling a rated flow. The EEV vale for a rated flow may be a vale for controlling a refrigerant to uniformly flow at a fixed amount through opening degree control.

The cooling sub valve 430 may be an EEV type valve. The cooling sub valve 430 may be used as a pressure equalization EEV of the air conditioner 1000 when switching from a heating operation to a cooling operation. The mode change control device 300a may control an opening degree to open the cooling sub valve 430 in a state before the indoor unit 200 starts the cooling operation after the heating operation has been stopped. When the cooling sub valve 430 is opened while operation of the indoor unit 200 is stopped, the pressure of the refrigerant in the high-pressure section may be increased. In other words, the cooling sub valve 430 may decrease the pressure of the refrigerant in the high-pressure section to decrease the pressure difference between the high-pressure section and the low-pressure section. This will be described in greater detail below with reference to a pressure equalization process (operation 503) of FIG. 5A.

When switching from the cooling operation to the heating operation, the indoor EEV 220 may be used as a pressure equalization EEV, and this will be described in greater detail below with reference to a pressure equalization process (operation 403) of FIG. 4A.

The indoor unit 200 may include an indoor fan 230 for exchanging heat with the indoor heat exchanger 210 by circulating indoor air, and a refrigerant temperature sensor. The refrigerant temperature sensor may include an inlet temperature sensor 241 configured to sense an inlet refrigerant temperature of the indoor heat exchanger 210, and an outlet temperature sensor 242 configured to sense an outlet refrigerant temperature of the indoor heat exchanger 210, but is not limited thereto.

The mode change control device 300a may further include supercoolers 440-1, 440-2, and 440-n, and a supercooling EEV 450. The supercoolers 440-1, 440-2, . . . , and 440-n may secure a supercooling degree of the indoor unit 200 performing the cooling operation. For example, the supercoolers 440-1, 440-2, . . . , and 440-n may supply, to a cooling cycle of an indoor unit (e.g., the indoor unit 200-1), a liquid refrigerant discharged by another indoor unit (e.g., the indoor unit 200-n) after the heating operation is performed. Accordingly, a sufficient amount of liquid refrigerant used for cooling of an indoor unit may be secured. For example, the nth indoor unit 200-n may discharge the liquid refrigerant to a liquid pipe after the heating operation. The discharged liquid refrigerant may pass through the nth supercooler 440-n to be introduced to the first indoor unit 200-1 again without returning to the outdoor unit 100. The supercooling EEV 450 may secure a superheating degree of the supercoolers 440-1, 440-2, . . . , and 440-n and prevent and/or reduce introduction of the liquid refrigerant.

FIG. 4A is a diagram for illustrating an example process in which an air conditioner switches from a cooling operation to a heating operation, according to various embodiments. FIG. 4B is a table illustrating a valve operation when the air conditioner of FIG. 4A switches from the cooling operation to the heating operation according to various embodiments. In FIGS. 4A and 4B, the air conditioner 1000 according to an embodiment of the disclosure may include the mode change control device 300a. For convenience of description, details that overlap those described with reference to FIGS. 1 to 3 may not be repeated here.

During a cooling operation process (operation 401), the air conditioner 1000 may perform the cooling operation by controlling the cooling main valve 420 and the indoor EEV 220 to be opened. The refrigerant in a high-pressure liquid state transmitted through the liquid pipe 316 may pass through the indoor EEV 220 to become the refrigerant in a low-pressure liquid state, then perform heat exchange in the indoor heat exchanger 210, and then become the refrigerant in a low-pressure gas state. The refrigerant in the low-pressure gas state may pass through the cooling main valve 420 and exit to the low-pressure gas pipe 314. The refrigerant in the low-pressure gas state may be transmitted to the outdoor unit 100. This corresponds to the cooling operation 201 of FIG. 2B. Also, during the cooling operation process (operation 401), because the cooling sub valve 430 is in an open state, the refrigerant in the low-pressure gas state may also exit to the low-pressure gas pipe 314 through the cooling sub valve 430. The heating main valve 410 may be in a closed state.

The air conditioner 1000 according to an embodiment of the disclosure may perform a cooling stop process (operation 402), the pressure equalization process (operation 403), and a heating operation process (operation 404) in the stated order, based on a switch command to switch from the cooling operation to the heating operation. The air conditioner 1000 may equalize the pressure at opposite sides of the heating main valve 410 before opening the heating main valve 410.

During the cooling stop process (operation 402), the air conditioner 1000 may stop the cooling operation by controlling the cooling main valve 420, the cooling sub valve 430, and the indoor EEV 220 to be closed. A flow of the refrigerant in the indoor unit 200 may be stopped while operation of the indoor unit 200 is stopped. In this case, the refrigerant pipe 312 may form the low-pressure section. The refrigerant in the refrigerant pipe 312 may be in a two-phase state in which a low-pressure liquid and a low-pressure gas coexist.

During the pressure equalization process (operation 403) through high pressurization of the indoor unit 200, the air conditioner 1000 may control the indoor EEV 220 to be opened to increase the pressure of the refrigerant flowing through the indoor unit 200. The air conditioner 1000 may open the indoor EEV 220 to a defined opening degree while operation is stopped, so as to use the indoor EEV 220 as a pressure equalization EEV. When the indoor EEV 220 is opened, a liquid refrigerant in a somewhat high-pressure state introduced through the liquid pipe 316 may pass through the indoor EEV 220 and flow to the indoor heat exchanger 210 and the refrigerant pipe 312. Accordingly, the pressure of the low-pressure section formed in the indoor heat exchanger 210 and the refrigerant pipe 312 may be increased. As a result, when the heating main valve 410 is opened for an operating mode switch, a refrigerant pressure difference between the high-pressure gas pipe 311 connected to the first side of the heating main valve 410 and the refrigerant pipe 312 connected to the second side of the heating main valve 410 may be decreased. When the indoor EEV 220 used as a pressure equalization EEV is opened to a defined opening degree, a flow rate of the refrigerant flowing through the indoor EEV 220 may be high. Here, the defined opening degree may denote an opening degree greater than an opening degree during a normal cooling operation. The defined opening degree may set to an appropriate opening degree that is small enough that noise is not generated when at least the indoor EEV 220 is suddenly opened and large enough that a time required for the pressure equalization control is not too long.

During the heating operation process (operation 404), the air conditioner 1000 may start the heating operation of the indoor unit 200 by controlling the heating main valve 410 to be opened while the refrigerant pressure in the indoor heat exchanger 210 and the refrigerant pipe 312 is increased. The air conditioner 1000 may use the indoor EEV 220 as an expansion device by opening the indoor EEV 220 to be greater than the defined opening degree. For example, during the heating operation, the indoor EEV 220 controls a flow rate, and thus, the opening degree may be controlled within a range (e.g., near the maximum opening degree) greater than that during the cooling operation.

When switching from the cooling operation to the heating operation, the air conditioner 1000 according to an embodiment of the disclosure may immediately close the cooling main valve 420 and prevent and/or reduce noise, impact, refrigerant pipe damage, or the like that may be caused when the heating main valve 410 is opened.

During the pressure equalization process (operation 403) according to an embodiment of the disclosure, the air conditioner 1000 may control the cooling sub valve 430 to be closed. However, when there is a valve malfunction due to a foreign matter being caught in the cooling sub valve 430 of an EEV type, the cooling sub valve 430 may not be completely closed even if the air conditioner 1000 controls the cooling sub valve 430 to be closed. When the cooling sub valve 430 is slightly opened, the refrigerant in the refrigerant pipe 312 connected to the second side of the heating main valve 410 may exit to the cooling sub valve 430, and thus, the refrigerant pressure in the refrigerant pipe 312 may not be increased or may be increased less. Accordingly, the refrigerant pressure difference between the high-pressure section and the low-pressure section at opposite sides of the heating main valve 410 may not be decreased. As a result, when the heating main valve 410 is opened while the refrigerant pressure difference is not decreased, significant noise and vibration may be generated in the indoor unit 200 and the mode change control device 300a. The air conditioner 1000 according to an embodiment of the disclosure may determine whether to perform the heating operation process (operation 404) after performing the pressure equalization process (operation 403) and then determining whether the pressure equalization has been successfully performed. This will be described in greater detail below with reference to FIGS. 11 and 12.

FIG. 5A is a diagram illustrating an example process in which an air conditioner switches from a heating operation to a cooling operation, according to various embodiments. FIG. 5B is a table illustrating a valve operation when the air conditioner of FIG. 5A switches from the heating operation to the cooling operation according to various embodiments. In FIGS. 5A and 5B, the air conditioner 1000 according to an embodiment of the disclosure may include the mode change control device 300a. For convenience of description, details that overlap those described with reference to FIGS. 1 to 3 may not be repeated here.

During a heating operation process (operation 501), the air conditioner 1000 may perform the heating operation by controlling the heating main valve 410 and the indoor EEV 220 to be opened. The refrigerant in a high-pressure gas state transmitted through the high-pressure gas pipe 311 may pass through the heating main valve 410, then perform heat exchange in the indoor heat exchanger 210, and then exit as a high-pressure liquid refrigerant and pass through the indoor EEV 220. The refrigerant in a low-pressure liquid state, which passed through the indoor EEV 220, may be transmitted to the outdoor unit 100 through the liquid pipe 316. This corresponds to the heating operation 202 of FIG. 2B. The cooling main valve 420 and the cooling sub valve 430 may be in closed states.

The air conditioner 1000 according to an embodiment of the disclosure may perform a heating stop process (operation 502), the pressure equalization process (operation 503), and a cooling operation process (operation 504) in the stated order, based on a switch command to switch from the heating operation to the cooling operation. The air conditioner 1000 may equalize the pressure at opposite sides of the cooling main valve 420 before opening the cooling main valve 420.

During the heating stop process (operation 502), the air conditioner 1000 may stop the heating operation by controlling the heating main valve 410 and the indoor EEV 220 to be closed. A flow of the refrigerant in the indoor unit 200 may be stopped while operation of the indoor unit 200 is stopped. In this case, the refrigerant pipe 312 may form the high-pressure section. The refrigerant in the refrigerant pipe 312 may be in a two-phase state in which a high-pressure liquid and a high-pressure gas coexist.

During the pressure equalization process (operation 503) through low pressurization of the indoor unit 200, the air conditioner 1000 may control the cooling sub valve 430 to be opened to decrease the pressure of the refrigerant flowing through the indoor unit 200. The air conditioner 1000 may use the cooling sub valve 430 in an open state as a pressure equalization EEV while operation is stopped. When the cooling sub valve 430 is opened, the refrigerant in the high-pressure state in the refrigerant pipe 312 may pass through the cooling sub valve 430 and flow to the low-pressure gas pipe 314. Accordingly, the pressure of the high-pressure section formed in the indoor heat exchanger 210 and the refrigerant pipe 312 may be decreased. As a result, when the cooling main valve 420 is opened for an operating mode switch, a refrigerant pressure difference between the low-pressure gas pipe 314 connected to the first side of the cooling main valve 420 and the refrigerant pipe 312 connected to the second side of the cooling main valve 420 may be decreased.

During the cooling operation process (operation 504), the air conditioner 1000 may start the cooling operation of the indoor unit 200 by controlling the cooling main valve 420 to be opened and the indoor EEV 220 to be opened while the refrigerant pressure in the indoor heat exchanger 210 and the refrigerant pipe 312 is decreased. Here, the heating main valve 410 may be in a closed state. The cooling sub valve 430 is illustrated as being in a closed state, but may alternatively in an open state. For example, during the cooling operation, the indoor EEV 220 operates as an expansion valve, and thus, the opening degree may be controlled within a range smaller than that during the heating operation.

When switching from the heating operation to the cooling operation, the air conditioner 1000 according to an embodiment of the disclosure may immediately close the heating main valve 410 and prevent and/or reduce noise, impact, refrigerant pipe damage, or the like that may be caused when the cooling main valve 420 is opened.

The air conditioner 1000 according to an embodiment of the disclosure may determine whether to perform the cooling operation process (operation 504) after performing the pressure equalization process (operation 503) and then determining whether the pressure equalization has been successfully performed. This will be described in greater detail below with reference to FIGS. 11 and 13.

Compared to a mode change control device 300c of FIGS. 8A to 9B, the mode change control device 300a of FIGS. 4A to 5B may not include a heating sub valve. The air conditioner 1000 including the mode change control device 300a may perform low pressurization (e.g., the pressure equalization process (operation 403)) on the refrigerant flowing through the indoor unit 200 using the indoor EEV 220 instead of a heating sub valve. Accordingly, costs of manufacturing the air conditioner 1000 including the mode change control device 300a may be reduced.

Hereinafter, the air conditioner 1000 including a mode change control device 300b, according to an embodiment of the disclosure, will be described in greater detail with reference to FIGS. 6A to 7B.

FIG. 6A is a diagram for illustrating an example process in which an air conditioner switches from a cooling operation to a heating operation, according to various embodiments. FIG. 6B is a table illustrating a valve operation when the air conditioner of FIG. 6A switches from the cooling operation to the heating operation according to various embodiments.

The air conditioner 1000 according to an embodiment of the disclosure may include the outdoor unit 100, the indoor unit 200, and the mode change control device 300b. The mode change control device 300b may include the heating EEV 610 and the cooling EEV 620. The mode change control device 300b of FIGS. 6A and 7A may correspond to the mode change control device 300 of FIGS. 1 to 2B. The heating EEV 610 of FIGS. 6A and 7A may correspond to the heating valve 310 of FIG. 2A. The cooling EEV 620 of FIGS. 6A and 7A may correspond to the cooling valve 320 of FIG. 2A. The mode change control device 300b differs from the mode change control device 300a of FIGS. 4A and 5A in that the mode change control device 300b includes the heating EEV 610 and the cooling EEV 620 instead of the heating main valve 410, the cooling main valve 420, and the cooling sub valve 430.

The heating EEV 610 and the cooling EEV 620 according to an embodiment of the disclosure may each be an EEV valve for controlling a fine flow rate. The EEV valve for a fine flow rate may be a valve for finely controlling a flow rate of a refrigerant through fine control of an opening degree. Accordingly, the heating EEV 610 and the cooling EEV 620 may control not only the flow rate of the refrigerant, but also a pressure of the refrigerant by adjusting the opening degree.

Each of the heating EEV 610 and the cooling EEV 620 according to an embodiment of the disclosure may be used as a pressure equalization EEV or a valve for the heating operation and the cooling operation, depending on a size of the opening degree. For example, the air conditioner 1000 may finely increase (e.g., a minimum opening degree) the opening degree of each of the heating EEV 610 and the cooling EEV 620 to use the same as the pressure equalization EEV of the air conditioner 1000. Alternatively, the air conditioner 1000 may increase the opening degree of each of the heating EEV 610 and the cooling EEV 620 to a higher opening degree to use the same as the valve for the heating operation and the cooling operation.

For example, the heating EEV 610 may be used as the pressure equalization EEV when switching from the cooling operation to the heating operation. This will be described with reference to a pressure equalization process (operation 603) of FIG. 6A. For example, the cooling EEV 620 may be used as the pressure equalization EEV when switching from the heating operation to the cooling operation. This will be described in greater detail below with reference to a pressure equalization process (operation 703) of FIG. 7A.

During a cooling operation process (operation 601), the air conditioner 1000 may perform the cooling operation by controlling the cooling EEV 620 and the indoor EEV 220 to be opened. The refrigerant in the high-pressure liquid state may be transmitted to the indoor EEV 220 through the liquid pipe 316, and the refrigerant in the low-pressure gas state may exit to the low-pressure gas pipe 314. This corresponds to the cooling operation 201 of FIG. 2B. The cooling EEV 620 may be opened to an opening degree greater than the minimum opening degree. Here, the heating EEV 610 may be in a closed state.

The air conditioner 1000 according to an embodiment of the disclosure may perform a cooling stop process (operation 602), the pressure equalization process (operation 603), and a heating operation process (operation 604) in the stated order, based on a switch command to switch from the cooling operation to the heating operation. The air conditioner 1000 may equalize the pressure at opposite sides of the heating EEV 610 before opening the heating EEV 610.

During the cooling stop process (operation 602), the air conditioner 1000 may stop the cooling operation by controlling the cooling EEV 620 and the indoor EEV 220 to be closed. A flow of the refrigerant in the indoor unit 200 may be stopped while operation of the indoor unit 200 is stopped. In this case, the refrigerant pipe 312 may form the low-pressure section.

During the pressure equalization process (operation 603) through high pressurization of the indoor unit 200, the air conditioner 1000 may control the heating EEV 610 to be opened to increase the pressure of the refrigerant flowing through the indoor unit 200. The air conditioner 1000 may open the heating EEV 610 to the minimum opening degree while operation is stopped, so as to use the heating EEV 610 as a pressure equalization EEV. When the heating EEV 610 is opened to the minimum opening degree, a gas refrigerant in a high-pressure state may flow through the high-pressure gas pipe 311 to the refrigerant pipe 312 and the indoor heat exchanger 210. Accordingly, the pressure of the low-pressure section formed in the refrigerant pipe 312 and the indoor heat exchanger 210 may be increased. As a result, when the heating EEV 610 is opened for an operating mode switch, a refrigerant pressure difference between the high-pressure gas pipe 311 connected to the first side of the heating EEV 610 and the refrigerant pipe 312 connected to the second side of the heating EEV 610 may be decreased. The air conditioner 1000 may control the opening degree of the heating EEV 610 used as the pressure equalization EEV to be the minimum opening degree so as to prevent and/or reduce the refrigerant pressure of opposite sides of the heating EEV 610 from rapidly changing.

During the heating operation process (operation 604), the air conditioner 1000 may start the heating operation of the indoor unit 200 by controlling the heating EEV 610 to be opened to an opening degree greater than the minimum opening degree while the refrigerant pressure in the indoor heat exchanger 210 and the refrigerant pipe 312 is increased.

When switching from the cooling operation to the heating operation, the air conditioner 1000 according to an embodiment of the disclosure may immediately close the cooling EEV 620 and prevent and/or reduce noise, impact, refrigerant pipe damage, or the like that may be caused when the heating EEV 610 is opened.

During the pressure equalization process (operation 603) according to an embodiment of the disclosure, the air conditioner 1000 may control the cooling EEV 620 to be closed. However, when there is a malfunction in the cooling EEV 620 of an EEV type, the cooling EEV 620 may be slightly opened. In this case, the refrigerant of the refrigerant pipe 312 may exit through the cooling EEV 620, and thus, the refrigerant pressure of the refrigerant pipe 312 may not be increased or may be increased less. Accordingly, the refrigerant pressure difference between the high-pressure section and the low-pressure section at opposite sides of the heating EEV 610 may not be decreased. As a result, when the heating EEV 610 is opened while the refrigerant pressure difference is not decreased, significant noise and vibration may be generated in the indoor unit 200 and the mode change control device 300b. The air conditioner 1000 according to an embodiment of the disclosure may determine whether to perform the heating operation process (operation 604) after performing the pressure equalization process (operation 603) and then determining whether the pressure equalization has been successfully performed. This will be described in greater detail below with reference to FIGS. 11 and 12.

FIG. 7A is a diagram illustrating an example process in which an air conditioner switches from a cooling operation to a heating operation, according to various embodiments. FIG. 7B is a table illustrating a valve operation when the air conditioner of FIG. 7A switches from the cooling operation to the heating operation according to various embodiments.

During a heating operation process (operation 701), the air conditioner 1000 may perform the heating operation by controlling the heating EEV 610 and the indoor EEV 220 to be opened. The refrigerant in the high-pressure gas state transmitted through the high-pressure gas pipe 311 may be transmitted to the heating EEV 610 and the refrigerant in the low-pressure liquid state may exit to the liquid pipe 316. This corresponds to the heating operation 202 of FIG. 2B. Here, the heating EEV 610 may be opened to an opening degree greater than the minimum opening degree. The cooling EEV 620 may be in a closed state.

The air conditioner 1000 according to an embodiment of the disclosure may perform a heating stop process (operation 702), the pressure equalization process (operation 703), and a cooling operation process (operation 704) in the stated order, based on a switch command to switch from the heating operation to the cooling operation. The air conditioner 1000 may equalize the pressure at opposite sides of the cooling EEV 620 before opening the cooling EEV 620.

During the heating stop process (operation 702), the air conditioner 1000 may stop the heating operation by controlling the heating EEV 610 and the indoor EEV 220 to be closed. A flow of the refrigerant in the indoor unit 200 may be stopped while operation of the indoor unit 200 is stopped. In this case, the refrigerant pipe 312 may form the high-pressure section.

During the pressure equalization process (operation 703) through low pressurization of the indoor unit 200, the air conditioner 1000 may control the cooling EEV 620 to be opened to decrease the pressure of the refrigerant flowing through the indoor unit 200. The air conditioner 1000 may open the cooling EEV 620 to the minimum opening degree while operation is stopped, so as to use the cooling EEV 620 as a pressure equalization EEV. When the cooling EEV 620 is opened to the minimum opening degree, a gas refrigerant in a low-pressure state may flow through the low-pressure gas pipe 314 to the refrigerant pipe 312 and the indoor heat exchanger 210. Accordingly, the pressure of the high-pressure section formed in the refrigerant pipe 312 and the indoor heat exchanger 210 may be decreased. As a result, when the cooling EEV 620 is opened for an operating mode switch, a refrigerant pressure difference between the low-pressure gas pipe 314 connected to the first side of the cooling EEV 620 and the refrigerant pipe 312 connected to the second side of the cooling EEV 620 may be decreased. The air conditioner 1000 may control the opening degree of the cooling EEV 620 used as the pressure equalization EEV to be the minimum opening degree so as to prevent and/or reduce the refrigerant pressure of opposite sides of the cooling EEV 620 from rapidly changing.

During the cooling operation process (operation 704), the air conditioner 1000 may start the cooling operation of the indoor unit 200 by controlling the cooling EEV 620 to be opened and the indoor EEV 220 to be opened while the refrigerant pressure in the indoor heat exchanger 210 and the refrigerant pipe 312 is decreased. The heating EEV 610 may be in a closed state.

When switching from the heating operation to the cooling operation, the air conditioner 1000 according to an embodiment of the disclosure may immediately close the heating EEV 610 and prevent and/or reduce noise, impact, refrigerant pipe damage, or the like that may be caused when the cooling EEV 620 is opened.

During the pressure equalization process (operation 703) according to an embodiment of the disclosure, the air conditioner 1000 may control the heating EEV 610 to be closed. However, when there is a malfunction in the heating EEV 610 of an EEV type, the heating EEV 610 may be slightly opened. In this case, the refrigerant in the high-pressure state may be introduced to the refrigerant pipe 312 through the heating EEV 610, and thus, the refrigerant pressure of the refrigerant pipe 312 may not be decreased or may be decreased less. Accordingly, the refrigerant pressure difference between the high-pressure section and the low-pressure section at opposite sides of the cooling EEV 620 may not be decreased. As a result, when the cooling EEV 620 is opened while the refrigerant pressure difference is not decreased, significant noise and vibration may be generated in the indoor unit 200 and the mode change control device 300b. The air conditioner 1000 according to an embodiment of the disclosure may determine whether to perform the cooling operation process (operation 704) after performing the pressure equalization process (operation 703) and then determining whether the pressure equalization has been successfully performed. This will be described in greater detail below with reference to FIGS. 11 and 13.

Hereinafter, the air conditioner 1000 including the mode change control device 300c, according to an embodiment of the disclosure, will be described in greater detail with reference to FIGS. 8A to 9B.

FIG. 8A is a diagram illustrating an example process in which an air conditioner switches from a cooling operation to a heating operation, according to various embodiments. FIG. 8B is a table illustrating a valve operation when the air conditioner of FIG. 8A switches from the cooling operation to the heating operation according to various embodiments.

The air conditioner 1000 according to an embodiment of the disclosure may include the outdoor unit 100, the indoor unit 200, and the mode change control device 300c. The mode change control device 300c may include a heating main valve 810, a cooling main valve 820, the heating sub valve 830, and the cooling sub valve 840. The mode change control device 300c of FIGS. 8A and 9A may correspond to the mode change control device 300 of FIGS. 1 to 2B. The heating main valve 810 of FIGS. 8A and 9A may correspond to the heating valve 310 of FIG. 2A. The cooling main valve 820 of FIGS. 8A and 9A may correspond to the cooling valve 320 of FIG. 2A. Compared to the mode change control device 300 of FIGS. 1 to 2B, the mode change control device 300c of FIGS. 8A and 9A may further include the heating sub valve 830 and the cooling sub valve 840. Compared to the mode change control device 300a of FIGS. 4A and 5A, the mode change control device 300c may further include the heating sub valve 830. Compared to the mode change control device 300b of FIGS. 6A and 7A, the mode change control device 300c may further include the heating sub valve 830 and the cooling sub valve 840.

The heating main valve 810 and the cooling main valve 820 according to an embodiment of the disclosure may each be a solenoid type valve. The heating main valve 810 and the cooling main valve 820 may completely open or completely close a fluid flow of a specific section through on control or off control. However, the disclosure is not limited thereto, and the heating main valve 810 and the cooling main valve 820 may each be an EEV type valve for controlling a rated flow. The heating main valve 810 and the cooling main valve 820 may respectively correspond to the heating main valve 410 and the cooling main valve 420 of FIG. 4A.

The heating sub valve 830 and the cooling sub valve 840 may each be an EEV type valve. The heating sub valve 830 and the cooling sub valve 840 may each be used as a pressure equalization EEV of the air conditioner 1000 when switching an operating mode. For example, the heating sub valve 830 may be used as the pressure equalization EEV when switching from the cooling operation to the heating operation. This will be described with reference to a pressure equalization process (operation 803) of FIG. 8A. For example, the cooling sub valve 840 may be used as the pressure equalization EEV when switching from the heating operation to the cooling operation. This will be described with reference to a pressure equalization process (operation 903) of FIG. 9A.

During a cooling operation process (operation 801), the air conditioner 1000 may perform the cooling operation by controlling the cooling main valve 820 and the indoor EEV 220 to be opened. The refrigerant in the high-pressure liquid state may be transmitted to the indoor EEV 220 through the liquid pipe 316, and the refrigerant in the low-pressure gas state may exit to the low-pressure gas pipe 314. This corresponds to the cooling operation 201 of FIG. 2B. Also, during the cooling operation process (operation 801), because the cooling sub valve 840 is in an open state, the refrigerant in the low-pressure gas state may also exit to the low-pressure gas pipe 314 through the cooling sub valve 840. The heating main valve 810 and the heating sub valve 830 may be in closed states.

The air conditioner 1000 according to an embodiment of the disclosure may perform a cooling stop process (operation 802), the pressure equalization process (operation 803), and a heating operation process (operation 804) in the stated order, based on a switch command to switch from the cooling operation to the heating operation. The air conditioner 1000 may equalize the pressure at opposite sides of the heating main valve 810 before opening the heating main valve 810.

During the cooling stop process (operation 802), the air conditioner 1000 may stop the cooling operation by controlling the cooling main valve 820, the cooling sub valve 840, and the indoor EEV 220 to be closed. A flow of the refrigerant in the indoor unit 200 may be stopped while operation of the indoor unit 200 is stopped. In this case, the refrigerant pipe 312 may form the low-pressure section.

During the pressure equalization process (operation 803) through high pressurization of the indoor unit 200, the air conditioner 1000 may control the heating sub valve 830 to be opened to increase the pressure of the refrigerant flowing through the indoor unit 200. The air conditioner 1000 may use the heating sub valve 830 in an open state as a pressure equalization EEV while operation is stopped. When the heating sub valve 830 is opened, the gas refrigerant in the high-pressure state may flow through the high-pressure gas pipe 311 to the refrigerant pipe 312 and the indoor heat exchanger 210. Accordingly, the pressure of the low-pressure section formed in the refrigerant pipe 312 and the indoor heat exchanger 210 may be increased. As a result, when the heating main valve 810 is opened for an operating mode switch, a refrigerant pressure difference between the high-pressure gas pipe 311 connected to the first side of the heating main valve 810 and the refrigerant pipe 312 connected to the second side of the heating main valve 810 may be decreased.

During the heating operation process (operation 804), the air conditioner 1000 may start the heating operation of the indoor unit 200 by controlling the heating main valve 810 to be opened to an opening degree greater than the minimum opening degree while the refrigerant pressure in the indoor heat exchanger 210 and the refrigerant pipe 312 is increased.

When switching from the cooling operation to the heating operation, the air conditioner 1000 according to an embodiment of the disclosure may immediately close the cooling main valve 820 and prevent and/or reduce noise, impact, refrigerant pipe damage, or the like that may be caused when the heating main valve 810 is opened.

During the pressure equalization process (operation 803) according to an embodiment of the disclosure, the air conditioner 1000 may control the cooling EEV 620 to be closed.

During the pressure equalization process (operation 803) according to an embodiment of the disclosure, the air conditioner 1000 may control the cooling sub valve 840 to be closed. However, when there is a malfunction in the cooling sub valve 840 of an EEV type, the cooling sub valve 840 may be slightly opened. In this case, the refrigerant of the refrigerant pipe 312 may exit through the cooling sub valve 840, and thus, the refrigerant pressure of the refrigerant pipe 312 may not be increased or may be increased less. Accordingly, the refrigerant pressure difference between the high-pressure section and the low-pressure section at opposite sides of the heating main valve 810 may not be decreased. As a result, when the heating main valve 810 is opened while the refrigerant pressure difference is not decreased, significant noise and vibration may be generated in the indoor unit 200 and the mode change control device 300c. The air conditioner 1000 according to an embodiment of the disclosure may determine whether to perform the heating operation process (operation 804) after performing the pressure equalization process (operation 803) and then determining whether the pressure equalization has been successfully performed. This will be described in greater detail below with reference to FIGS. 11 and 12.

FIG. 9A is a diagram illustrating an example process in which an air conditioner switches from a cooling operation to a heating operation, according to various embodiments. FIG. 9B is a table illustrating a valve operation when the air conditioner of FIG. 9A switches from the cooling operation to the heating operation.

During a heating operation process (operation 901), the air conditioner 1000 may perform the heating operation by controlling the heating main valve 810 and the indoor EEV 220 to be opened. The refrigerant in the high-pressure gas state transmitted through the high-pressure gas pipe 311 may be transmitted to the heating main valve 810 and the refrigerant in the low-pressure liquid state may exit to the liquid pipe 316. This corresponds to the heating operation 202 of FIG. 2B. During the heating operation process (operation 901), because the heating sub valve 830 is in an open state, the refrigerant in the high-pressure gas state may also be transmitted to the high-pressure gas pipe 311 through the heating sub valve 830. The cooling main valve 820 and the cooling sub valve 840 may be in closed states.

The air conditioner 1000 according to an embodiment of the disclosure may perform a heating stop process (operation 902), the pressure equalization process (operation 903), and a cooling operation process (operation 904) in the stated order, based on a switch command to switch from the heating operation to the cooling operation. The air conditioner 1000 may equalize the pressure at opposite sides of the cooling main valve 820 before opening the cooling main valve 820.

During the heating stop process (operation 902), the air conditioner 1000 may stop the heating operation by controlling the heating main valve 810, the heating sub valve 830, and the indoor EEV 220 to be closed. A flow of the refrigerant in the indoor unit 200 may be stopped while operation of the indoor unit 200 is stopped. In this case, the refrigerant pipe 312 may form the high-pressure section.

During the pressure equalization process (operation 903) through low pressurization of the indoor unit 200, the air conditioner 1000 may control the cooling sub valve 840 to be opened to decrease the pressure of the refrigerant flowing through the indoor unit 200. This may correspond to the pressure equalization process (operation 503) of FIG. 5A.

During the cooling operation process (operation 904), the air conditioner 1000 may start the cooling operation of the indoor unit 200 by controlling the cooling main valve 820 to be opened and the indoor EEV 220 to be opened while the refrigerant pressure in the indoor heat exchanger 210 and the refrigerant pipe 312 is decreased. The heating main valve 810 may be in a closed state.

When switching from the heating operation to the cooling operation, the air conditioner 1000 according to an embodiment of the disclosure may immediately close the heating main valve 810 and prevent and/or reduce noise, impact, refrigerant pipe damage, or the like that may be caused when the cooling main valve 820 is opened.

During the pressure equalization process (operation 903) according to an embodiment of the disclosure, the air conditioner 1000 may control the heating sub valve 830 to be closed. However, when there is a malfunction in the heating sub valve 830 of an EEV type, the heating sub valve 830 may be slightly opened. In this case, the refrigerant in the high-pressure state may be introduced to the refrigerant pipe 312 through the heating sub valve 830, and thus, the refrigerant pressure of the refrigerant pipe 312 may not be decreased or may be decreased less. Accordingly, the refrigerant pressure difference between the high-pressure section and the low-pressure section at opposite sides of the cooling main valve 820 may not be decreased. As a result, when the cooling main valve 820 is opened while the refrigerant pressure difference is not decreased, significant noise and vibration may be generated in the indoor unit 200 and the mode change control device 300c. The air conditioner 1000 according to an embodiment of the disclosure may determine whether to perform the cooling operation process (operation 904) after performing the pressure equalization process (operation 903) and then determining whether the pressure equalization has been successfully performed. This will be described in greater detail below with reference to FIGS. 11 and 13.

FIG. 10 is a block diagram illustrating example configurations of an indoor unit, a mode change control device, and an outdoor unit, according to various embodiments.

Referring to FIG. 10, the air conditioner 1000 according to an embodiment of the disclosure may include the outdoor unit 100, the indoor unit 200, and the mode change control device 300. The outdoor unit 100 and the indoor unit 200, the outdoor unit 100 and the mode change control device 300, and the indoor unit 200 and the mode change control device 300 may perform bi-directional communication. The outdoor unit 100, the indoor unit 200, and the mode change control device 300 may transmit and receive various signals generated during operation of the air conditioner 1000.

An outdoor unit communicator 1030, an indoor unit communicator 2030, and a central communicator 3030, each including various communication circuitry, according to an embodiment of the disclosure, may transmit and receive various types of data with a component in the air conditioner 1000 or an external device, according to control by an outdoor unit processor 1010, an indoor unit processor 2010, and a central processor 3010, respectively. Each of the outdoor unit communicator 1030, the indoor unit communicator 2030, and the central communicator 3030 may include a port connecting a wired cable for performing wired communication between the outdoor unit 100, the indoor unit 200, and the mode change control device 300. The outdoor unit communicator 1030, the indoor unit communicator 2030, and the central communicator 3030 may transmit a received control signal to the outdoor unit processor 1010, the indoor unit processor 2010, and the central processor 3010, respectively.

The outdoor unit 100 according to an embodiment of the disclosure may include the outdoor unit processor (e.g., including processing circuitry) 1010, an outdoor unit memory 1020, and the outdoor unit communicator 1030. However, not all of the components shown in FIG. 10 are essential components. The outdoor unit 100 may be implemented by more or fewer components than those illustrated in FIG. 10.

The outdoor unit processor 1010 may include various processing circuitry and control all operations of the outdoor unit 100. The outdoor unit processor 1010 may be electrically connected to components of the outdoor unit 100 and control operations of each component. The outdoor unit processor 1010 may communicate with the indoor unit 200 or the mode change control device 300 through the outdoor unit communicator 1030. The outdoor unit processor 1010 may control components of the outdoor unit 100, based on information about a user input received from the indoor unit 200 or the mode change control device 300. For example, the outdoor unit processor 1010 may control operations of a compressor, an outdoor heat exchanger, an expansion device, a flow path switch valve, an accumulator, or an outdoor circulation fan, based on a control signal received through the outdoor unit communicator 1030. The refrigerant may circulate along a refrigerant circulation circuit including a compressor, a flow path switch valve, an outdoor heat exchanger, an expansion valve, and an indoor heat exchanger, under control by the outdoor unit processor 1010.

The outdoor unit memory 1020 may store programs for processes and controls by the outdoor unit processor 1010 and may store data input to or output from the outdoor unit 100.

The indoor unit 200 according to an embodiment of the disclosure may include the indoor unit processor (e.g., including processing circuitry) 2010, an indoor unit memory 2020, the indoor unit communicator 2030, an indoor unit sensor 2040, an input/output interface (e.g., including circuitry) 2050, an indoor unit driver 2060, and the indoor EEV 220. However, not all of the components shown in FIG. 10 are essential components. The indoor unit 200 may be implemented by more or fewer components than those illustrated in FIG. 10.

The indoor unit processor 2010 may include various processing circuitry and control all operations of the indoor unit 200. For example, the indoor unit processor 2010 may execute a program stored in the indoor unit memory 2020 to control the indoor unit communicator 2030, the indoor unit sensor 2040, the input/output interface 2050, and the indoor unit driver 2060. Also, the indoor unit processor 2010 may generate a control signal for adjusting an opening degree of the indoor EEV 220 and a control signal for controlling an indoor circulation fan.

The indoor unit processor 2010 may obtain a user input from a user terminal through the indoor unit communicator 2030, and obtain the user input through a remote controller or directly through the input/output interface 2050. The indoor unit processor 2010 may control components of the indoor unit 200 such that an operation of the air conditioner 1000, corresponding to the received user input, is performed. The indoor unit processor 2010 may generate a control signal corresponding to a user input, and transmit the generated control signal to the outdoor unit 100 or to the mode change control device 300. Also, for example, the indoor unit processor 2010 may transmit, to the outdoor unit 100 or the mode change control device 300 through the indoor unit communicator 2030, a sensing value detected by the indoor unit sensor 2040. The indoor unit processor 2010 may transmit a detected error code to the outdoor unit 100 or the mode change control device 300 through the indoor unit communicator 2030.

The indoor unit memory 2020 may store programs for processes and controls by the indoor unit processor 2010 and may store data input to or output from the indoor unit 200.

The indoor unit sensor 2040 may include a temperature sensor provided in a pre-determined space inside or outside a housing of the indoor unit 200. For example, the indoor unit sensor 2040 may include refrigerant temperature sensors respectively sensing temperatures of an inlet, a middle, and/or an outlet of a refrigerant pipe passing through the indoor heat exchanger. For example, the indoor unit sensor 2040 may include refrigerant pressure sensors respectively sensing pressures of an inlet, a middle, and/or an outlet of the refrigerant pipe passing through the indoor heat exchanger. For example, the refrigerant temperature sensor may include the inlet temperature sensor 241 and the outlet temperature sensor 242 of FIG. 2A.

The input/output interface 2050 may include various circuitry including an input interface and an output interface. The input/output interface 2050 may be electrically connected to the indoor unit processor 2010. This will be described in further detail with reference to FIG. 16.

The indoor unit driver 2060 may include various circuitry and drive the indoor EEV 220, based on a control signal of the indoor unit processor 2010. For example, the indoor unit driver 2060 may open or close the indoor EEV 220 by controlling an opening degree of the indoor EEV 220.

The mode change control device 300 according to an embodiment of the disclosure may include the central processor (e.g., including processing circuitry) 3010, a central memory 3020, the central communicator (e.g., including communication circuitry) 3030, an input/output interface (e.g., including various circuitry) 3040, a central driver (e.g., including various circuitry) 3050, the heating valve 310, and the cooling valve 320. However, not all of the components shown in FIG. 10 are essential components. The mode change control device 300 may be implemented by more or fewer components than those illustrated in FIG. 10.

The central processor 3010 may include various processing circuitry and control all operations of the mode change control device 300. For example, the central processor 3010 may execute a program stored in the central memory 3020 to control the central communicator 3030, the input/output interface 3040, and the central driver 3050. Also, the central processor 3010 may generate a control signal for controlling the heating valve 310 and the cooling valve 320.

The central processor 3010 may communicate with the indoor unit 200 or the outdoor unit 100 through the central communicator 3030. The central processor 3010 may control components of the mode change control device 300, based on information about a user input received from the indoor unit 200 or the outdoor unit 100. For example, when a control signal corresponding to a user input of selecting an operating mode, such as a cooling operation, a heating operation, a ventilation operation, a defrosting operation, or a dehumidification operation, is received from the indoor unit 200, the central processor 3010 may control components of the mode change control device 300 such that an operation of the air conditioner 1000, corresponding to the selected operating mode, is performed. For example, the control signal may control, based on the control signal received through the central communicator 3030, operations of the supercooler 440-1, 440-2, . . . , 440-n and the supercooling EEV 450 of FIG. 3, the heating main valve 410, the cooling main valve 420, and the cooling sub valve 430 of FIG. 4A, the heating EEV 610 and the cooling EEV 620 of FIG. 6A, and the heating main valve 810, the cooling main valve 820, the heating sub valve 830, and the cooling sub valve 840 of FIG. 8A.

The input/output interface 3040 may include various circuitry including an input interface including a switch, a button, or the like to receive a control command for the mode change control device 300 from the user or an administrator. The input/output interface 3040 may include an output interface including a display panel or the like to output an operating state of the mode change control device 300. For example, the input/output interface 3040 may receive a control command according to an operating mode switch from the user or the administrator. For example, the input/output interface 3040 may display an error code according to a valve malfunction.

The central driver 3050 may include various circuitry and drive the heating valve 310 and the cooling valve 320 according to control by the central processor 3010. For example, the central driver 3050 may generate a driving current to open or close the heating valve 310 and the cooling valve 320, and provide the driving current to the heating valve 310 and the cooling valve 320.

The central memory 3020 may store a program and data related to operations of the mode change control device 300, and store data input to the mode change control device 300 or output from the mode change control device 300.

A pressure equalization control method and a pressure equalization control error detection method, according to an embodiment of the disclosure, may be distributed between the outdoor unit 100, the indoor unit 200, and the mode change control device 300, or may be individually performed by the outdoor unit 100, the indoor unit 200, and the mode change control device 300.

At least one of the outdoor unit processor 1010, the indoor unit processor 2010, or the central processor 3010, according to an embodiment of the disclosure, may perform a first operation corresponding to one of the cooling operation or the heating operation, stop the first operation based on a switch command to switch from the first operation to a second operation corresponding to the other one of the cooling operation or the heating operation, perform pressure equalization control such that a refrigerant pressure difference of opposite sides of a transfer valve for the second operation is reduced while the first operation is stopped, determine whether the refrigerant pressure difference has been reduced, and determine whether to perform the second operation based on a result of the determination.

For example, the indoor unit processor 2010 may perform the first operation corresponding to one of the cooling operation or the heating operation by opening the indoor EEV 220. The indoor unit processor 2010 may obtain, through an input interface, the switch command to switch from the first operation to the second operation corresponding to the other one of the cooling operation or the heating operation. The indoor unit processor 2010 may stop the first operation by controlling the indoor EEV 220 to be closed, based on the switch command. The indoor unit processor 2010 may transmit, to the outdoor unit 100 and the mode change control device 300, the control signal corresponding to the switch command through the indoor unit communicator 2030. While the first operation is stopped, the indoor unit processor 2010 may determine whether the refrigerant pressure difference of the opposite sides of the transfer valve for the second operation has been reduced. The indoor unit processor 2010 may determine whether to perform the second operation by opening the indoor EEV 220, based on the result of the determination.

For example, the central processor 3010 may receive the control signal corresponding to the switch command from the indoor unit 200 through the central communicator 3030. The central processor 3010 may perform pressure equalization control based on the switch command.

For example, at least one of the indoor unit processor 2010 or the central processor 3010 may control a pressure equalization EEV to be opened for the pressure equalization control. For example, when the pressure equalization EEV is provided in the indoor unit 200, the indoor unit processor 2010 may control the pressure equalization EEV to be opened while the first operation is stopped. For example, when the pressure equalization EEV is provided in the mode change control device 300, the central processor 3010 may control the pressure equalization EEV to be opened while the first operation is stopped.

For example, the indoor unit processor 2010 may detect a pressure equalization control error. The indoor unit processor 2010 may obtain a first time point refrigerant temperature before the pressure equalization control is performed, through a refrigerant temperature sensor. The first time point refrigerant temperature may be data sensed at a time point before the pressure equalization control is performed while the first operation is stopped. The indoor unit processor 2010 may obtain a second time point refrigerant temperature after the pressure equalization control is performed, through the refrigerant temperature sensor. The indoor unit processor 2010 may determine whether a temperature difference between the first time point refrigerant temperature and the second time point refrigerant temperature corresponds to a set condition. Based on determining that the temperature difference corresponds to the set condition, the indoor unit processor 2010 may control the indoor EEV 220 to be opened and transmit the error code to the mode change control device 300 through the indoor unit communicator 2030. Based on determining that the temperature difference does not correspond to the set condition, the indoor unit processor 2010 may control the indoor EEV 220 to be closed. For example, the indoor unit processor 2010 may determine that the temperature difference corresponds to the set condition when the temperature difference is greater than a defined value.

FIG. 11 is a flowchart illustrating an example method of detecting a pressure equalization control error when switching an operating mode of an air conditioner, according to various embodiments. FIG. 11 will be described with reference to FIG. 10.

Referring to FIG. 11, in operation 1110, the air conditioner 1000 may perform the first operation. For example, when the first operation is the cooling operation, the second operation may be the heating operation. For example, when the first operation is the heating operation, the second operation may be the cooling operation. For example, operation 1110 may correspond to at least one of the cooling operation process (operation 401) of FIG. 4A, the heating operation process (operation 501) of FIG. 5A, the cooling operation process (operation 601) of FIG. 6A, the heating operation process (operation 701) of FIG. 7A, the cooling operation process (operation 801) of FIG. 8A, or the heating operation process (operation 901) of FIG. 9A.

In operation 1120, the air conditioner 1000 may stop the first operation based on the operating mode switch command to switch from the first operation to the second operation.

The air conditioner 1000 according to an embodiment of the disclosure may receive the user input corresponding to the operating mode switch command to switch from the first operation to the second operation. The user input corresponding to the operating mode switch command may include an operating mode setting input of selecting the cooling operation or the heating operation, or an indoor temperature setting input of setting an indoor temperature. For example, the indoor unit 200 may receive the user input corresponding to the operating mode switch command. However, the disclosure is not limited thereto, and the user input corresponding to the operating mode switch command may be received by the mode change control device 300 or the outdoor unit 100. This will be described in further detail with reference to FIG. 14.

The air conditioner 1000 according to an embodiment of the disclosure may stop the first operation based on the control signal corresponding to the operating mode switch command. For example, the indoor unit 200 may control the indoor EEV 220 to be closed, based on the control signal corresponding to the operating mode switch command. For example, the mode change control device 300 may control the heating valve 310 to be closed, based on a control signal corresponding to a switch command to switch from the heating operation to the cooling operation. The mode change control device 300 may control the heating operation to stop. For example, the mode change control device 300 may control the cooling valve 320 to be closed, based on a control signal corresponding to a switch command to switch from the cooling operation to the heating operation. The mode change control device 300 may control the cooling operation to stop.

For example, operation 1120 may correspond to at least one of the cooling stop process (operation 402) of FIG. 4A, the heating stop process (operation 502) of FIG. 5A, the cooling stop process (operation 602) of FIG. 6A, the heating stop process (operation 702) of FIG. 7A, the cooling stop process (operation 802) of FIG. 8A, or the heating stop process (operation 902) of FIG. 9A.

In operation 1130, the air conditioner 1000 may perform the pressure equalization control while the first operation is stopped. The air conditioner 1000 may perform control to equalize the refrigerant pressure difference of the opposite sides of the transfer valve for the second operation, while the first operation is stopped.

For example, the air conditioner 1000 may control the pressure equalization EEV while the heating operation or the cooling operation is stopped. For example, operation 1130 may correspond to at least one of the pressure equalization process (operation 403) of FIG. 4A, the pressure equalization process (operation 503) of FIG. 5A, the pressure equalization process (operation 603) of FIG. 6A, the pressure equalization process (operation 703) of FIG. 7A, the pressure equalization process (operation 803) of FIG. 8A, or the pressure equalization process (operation 903) of FIG. 9A.

In operation 1140, the air conditioner 1000 may determine whether the refrigerant pressure difference of the opposite sides of the transfer valve has been reduced. According to an embodiment of the disclosure, the air conditioner 1000 may determine whether to perform a switched operation process, based on a result of determining whether the refrigerant pressure difference of the opposite sides of the transfer valve has been reduced. Here, the transfer valve for determining whether the refrigerant pressure difference has been reduced may be the transfer valve for the second operation. For example, when the first operation is the cooling operation and the second operation is the heating operation, the transfer valve may be the heating valve 310. For example, when the first operation is the heating operation and the second operation is the cooling operation, the transfer valve may be the cooling valve 320.

The air conditioner 1000 may determine whether the pressure equalization according to operation 1130 has been normally performed to prevent and/or reduce noise, vibration, or damage generated due to the refrigerant pressure difference of the opposite sides of the transfer valve when the transfer valve is suddenly opened according to the operating mode switch. For example, to determine whether the pressure equalization control has been normally performed, the air conditioner 1000 may identify a range of a change in the pressure of the refrigerant flowing at the indoor unit 200 before and after the pressure equalization control. For example, when the pressure of the refrigerant flowing at the indoor unit 200 has been largely changed before and after the pressure equalization control, the air conditioner 1000 may identify that the refrigerant pressure difference has been normally reduced.

According to an embodiment of the disclosure, the air conditioner 1000 may use a refrigerant temperature sensor configured to detect a temperature of a refrigerant pipe passing through an indoor heat exchanger to indirectly determine an increase or a decrease of the refrigerant pressure of the transfer valve at the indoor unit 200. For example, the temperature of the refrigerant of the indoor heat exchanger may be increased or decreased as the refrigerant pressure of the indoor heat exchanger is increased or decreased. The air conditioner 1000 may determine whether the pressure difference of the opposite sides of the transfer valve has been reduced through the refrigerant temperature sensor. For example, the air conditioner 1000 may detect the first time point refrigerant temperature using the refrigerant temperature sensor, before operation 1130. The air conditioner 1000 may detect the second time point refrigerant temperature using the refrigerant temperature sensor, after operation 1130. The air conditioner 1000 may determine whether the temperature difference between the first time point refrigerant temperature and the second time point refrigerant temperature corresponds to the set condition. For example, the air conditioner 1000 may determine that the range of change in the refrigerant pressure is great when the temperature difference between the first time point refrigerant temperature and the second time point refrigerant temperature is greater than the defined value. The air conditioner 1000 may determine that the refrigerant pressure difference has been reduced when the range of change in the refrigerant pressure at the indoor unit 200 is great. Here, the defined value may be a reference temperature for determining whether the refrigerant pressure has been normally changed according to the pressure equalization control. Specific applications of each operating mode will be described with reference to FIGS. 12 and 13. When it is determined that the temperature of the indoor heat exchanger has not reached a defined level even after the pressure equalization control is completed, the air conditioner 1000 may control operation to stop. The air conditioner 1000 may switch the operating mode only when the temperature of the indoor heat exchanger has reached the defined level after the pressure equalization control is completed.

According to an embodiment of the disclosure, the air conditioner 1000 may directly determine whether the range of change in the refrigerant pressure at the indoor unit 200 before and after the pressure equalization is great using a refrigerant pressure sensor configured to detect the pressure of the refrigerant pipe passing through the indoor heat exchanger. For example, the air conditioner 1000 may detect a first time point refrigerant pressure using the refrigerant pressure sensor before operation 1130, and detect a second time point refrigerant pressure using the refrigerant pressure sensor after operation 1130. The air conditioner 1000 may determine that the range of change in the refrigerant pressure is great when a pressure difference between the first time point refrigerant pressure and the second time point refrigerant pressure is greater than a defined value. Here, the defined value may be a reference pressure for determining whether the refrigerant pressure has been normally changed according to the pressure equalization control.

According to an embodiment of the disclosure, the defined value may be determined based on the refrigerant pressure of the outdoor unit 100. For example, a change in the temperature of the indoor heat exchanger may vary depending on the refrigerant pressure of the outdoor unit 100. When the refrigerant pressure of the outdoor unit 100 is high, the temperature of the indoor heat exchanger may be relatively high. Also, when the refrigerant pressure of the outdoor unit 100 is low, the temperature of the indoor heat exchanger may be relatively low. Accordingly, a range of change in the temperature between the first time point refrigerant temperature and the second time point refrigerant temperature may vary depending on the refrigerant pressure of the outdoor unit 100. A range of change in the pressure between the first time point refrigerant pressure and the second time point refrigerant pressure may also vary depending on the refrigerant pressure of the outdoor unit 100. Because the air conditioner 1000 may differently determine the defined value according to the refrigerant pressure of the outdoor unit 100, the air conditioner 1000 may further accurately determine a malfunction of a valve.

According to an embodiment of the disclosure, the air conditioner 1000 may determine whether the pressure equalization control has been normally performed by directly detecting the refrigerant pressure of the opposite sides of the transfer valve, after operation 1130. For example, the air conditioner 1000 may detect the refrigerant pressure of the second side (side at the indoor unit 200) of the transfer valve through the refrigerant pressure sensor. When a value of the refrigerant pressure of the first side (side at the outdoor unit 100) of the transfer valve is known, the air conditioner 1000 may determine whether the refrigerant pressure at the first side and the refrigerant pressure at the second side are close to each other.

In operation 1150, when it is determined that the refrigerant pressure difference of the opposite sides of the transfer valve has been reduced, the air conditioner 1000 may perform the second operation.

For example, operation 1150 may correspond to at least one of the heating operation process (operation 404) of FIG. 4A, the cooling operation process (operation 504) of FIG. 5A, the heating operation process (operation 604) of FIG. 6A, the cooling operation process (operation 704) of FIG. 7A, the heating operation process (operation 804) of FIG. 8A, or the cooling operation process (operation 904) of FIG. 9A.

In operation 1160, when it is determined that the refrigerant pressure difference of the opposite sides of the transfer valve has not been reduced, the air conditioner 1000 may transmit an error code and stop the operation.

For example, when it is determined that the refrigerant pressure difference of the opposite sides of the transfer valve has not been reduced, the air conditioner 1000 may identify that an EEV type valve included in the air conditioner 1000 malfunctions. The air conditioner 1000 may determine that the pressure equalization has not been normally performed due to a valve malfunction.

For example, the indoor unit 200 may identify the valve malfunction and generate the error code. The error code may include information indicating that the pressure equalization has not been normally performed due to a malfunction of the EEV type valve included in the air conditioner 1000.

For example, the indoor unit 200 may transmit the error code to the mode change control device 300 through the indoor unit communicator 2030. The indoor unit 200 may control an operation of the indoor unit 200 to stop. The indoor unit 200 may display the error code through a display. The mode change control device 300 may control an operation of the mode change control device 300 to stop, based on the error code received from the indoor unit 200 through the central communicator 3030.

Accordingly, the air conditioner 1000 may prevent and/or reduce noise, vibration, and an impact from being generated in the air conditioner 1000 when a switched operation is performed while the pressure equalization has not been normally performed due to the malfunction of the EEV type valve included in the air conditioner 1000.

Operations 1140 to 1160 are illustrated as being performed by the indoor unit 200, but the disclosure is not limited thereto. For example, some or all of operations 1140 to 1160 may be distributed between the outdoor unit 100, the indoor unit 200, and the mode change control device 300, or may be individually performed by the outdoor unit 100, the indoor unit 200, and the mode change control device 300.

FIG. 12 is a signal flow diagram illustrating an example method of detecting a pressure equalization control error when an air conditioner switches from a cooling operation to a heating operation, according to various embodiments. FIG. 12 will be described in with reference to FIG. 10.

Referring to FIG. 12, in operation 1210, the indoor unit 200 and the mode change control device 300 may perform the cooling operation. For example, operation 1210 may include operation 1213 and operation 1217. In operation 1213, the indoor unit 200 may control the indoor EEV 220 to be opened for the cooling operation. In operation 1217, the mode change control device 300 may control the cooling valve 320 to be opened for the cooling operation.

Here, operation 1210 may correspond to at least one of the cooling operation process (operation 401) of FIG. 4A, the cooling operation process (operation 601) of FIG. 6A, or the cooling operation process (operation 801) of FIG. 8A. The cooling valve 320 may correspond to at least one of the cooling main valve 420 of FIG. 4A, the cooling EEV 620 of FIG. 6A, or the cooling main valve 820 of FIG. 8A. The heating valve 310 may correspond to at least one of the heating main valve 410 of FIG. 5A, the heating EEV 610 of FIG. 7A, or the heating main valve 810 of FIG. 9A. Operation 1210 may correspond to operation 1110 of FIG. 11.

In operation 1220, the indoor unit 200 may receive the user input corresponding to the operating mode switch command. For example, when a heating operation setting input is received while the cooling operation is performed, the indoor unit 200 may generate a control signal for performing a switch operation from the cooling operation to the heating operation. In operation 1225, the indoor unit 200 may transmit the control signal corresponding to the operating mode switch command to the mode change control device 300 through the indoor unit communicator 2030. The mode change control device 300 may receive the control signal corresponding to the operating mode switch command from the indoor unit 200 through the central communicator 3030.

In operation 1230, the indoor unit 200 and the mode change control device 300 may stop the cooling operation, based on the user input corresponding to the operating mode switch command. For example, operation 1230 may include operation 1233 and operation 1237. In operation 1233, the indoor unit 200 may control the indoor EEV 220 to be closed to stop the cooling operation. In operation 1237, the mode change control device 300 may control the cooling valve 320 to be closed to stop the cooling operation.

In operation 1240, the indoor unit 200 may detect a first temperature of the indoor heat exchanger. The first temperature may be the first time point refrigerant temperature obtained through the refrigerant temperature sensor configured to detect a temperature of the refrigerant passing through the indoor heat exchanger. The first time point refrigerant temperature may be a temperature before the pressure equalization control is performed.

In operation 1250, the indoor unit 200 and the mode change control device 300 may perform the pressure equalization control for high pressurization of the refrigerant of the indoor unit 200. The air conditioner 1000 may increase the refrigerant pressure in the low-pressure section formed at the second side (side at the indoor unit 200) of the heating valve 310 so as to reduce the refrigerant pressure difference between the low-pressure section and the high-pressure section formed at the first side (side at the outdoor unit 100) of the heating valve 310 and the second side (side at the indoor unit 200) of the heating valve 310.

For example, referring to the pressure equalization process (operation 403) of FIG. 4A, when the indoor EEV 220 is used as a pressure equalization EEV for switching from the cooling operation to the heating operation, the indoor unit 200 may open the indoor EEV 220 to a defined opening degree while the heating main valve 410 and the cooling main valve 420 are in closed states. The air conditioner 1000 may open the indoor EEV 220 to increase the refrigerant pressure of the low-pressure section formed at the second side (side at the indoor unit 200) of the heating main valve 410.

For example, referring to the pressure equalization process (operation 603) of FIG. 6A, when the heating EEV 610 is used as a pressure equalization EEV for switching from the cooling operation to the heating operation, the mode change control device 300b may control the heating EEV 610 to be opened to a minimum opening degree. The air conditioner 1000 may open the heating EEV 610 to a minimum opening degree to increase the refrigerant pressure of the low-pressure section formed at the second side (side at the indoor unit 200) of the heating EEV 610.

For example, referring to the pressure equalization process (operation 803) of FIG. 8A, when the heating sub valve 830 is used as a pressure equalization EEV for switching from the cooling operation to the heating operation, the mode change control device 300c may control the heating sub valve 830 to be opened while the heating main valve 810 and the cooling main valve 820 are in closed states. The air conditioner 1000 may open the heating sub valve 830 to increase the refrigerant pressure of the low-pressure section formed at the second side (side at the indoor unit 200) of the heating main valve 810.

In operation 1260, the indoor unit 200 may detect a second temperature of the indoor heat exchanger. The second temperature may be the second time point refrigerant temperature obtained through the refrigerant temperature sensor configured to detect a temperature of the refrigerant passing through the indoor heat exchanger. The second time point refrigerant temperature may be a temperature after the pressure equalization control is performed. Here, the first time point refrigerant temperature and the second time point refrigerant temperature may be temperatures of a same location from among an inlet, a middle, and an outlet of the refrigerant pipe passing through the indoor heat exchanger, measured at different time points.

In operation 1270, the indoor unit 200 may determine whether a range of a temperature increase between the first time point refrigerant temperature and the second time point refrigerant temperature is greater than a defined value. Here, the defined value may be a reference temperature for determining whether the refrigerant pressure has been normally changed according to the pressure equalization control. For example, when the refrigerant pressure has been normally changed according to the pressure equalization control, the second time point refrigerant temperature may be greater than the first time point refrigerant temperature by about 20° C. In this case, the defined value may be about 15° C. The indoor unit 200 may determine that the pressure equalization control has been normally performed when the range of the temperature increase between the first time point refrigerant temperature and the second time point refrigerant temperature is greater than 15° C.

Operations 1240 to 1270 may correspond to operations 1130 and 1140 of FIG. 11.

In operation 1280, the indoor unit 200 may determine that the pressure equalization control has been normally performed when the range of the temperature increase between the first time point refrigerant temperature and the second time point refrigerant temperature is greater than the defined value, and perform the heating operation. For example, operation 1280 may include operation 1283 and operation 1287. In operation 1283, the indoor unit 200 may control the indoor EEV 220 to be opened to perform the heating operation. The indoor unit 200 may generate a control signal for performing the heating operation and transmit the control signal to the mode change control device 300, but the disclosure is not limited thereto. In operation 1287, the mode change control device 300 may control the heating valve 310 to be opened to perform the heating operation. For example, the mode change control device 300 may control the heating valve 310 to be opened, based on receiving the control signal for performing the heating operation. Here, operation 1280 may correspond to operation 1150 of FIG. 11, and operation 1290 may correspond to operation 1160 of FIG. 11.

In operation 1290, the indoor unit 200 may determine that the pressure equalization control has not been normally performed when the range of the temperature increase between the first time point refrigerant temperature and the second time point refrigerant temperature is equal to or lower than the defined value, and stop the operation. For example, operation 1290 may include operations 1293, 1295, 1297, and 1299. In operation 1293, the indoor unit 200 may generate an error code when the pressure equalization control has not been normally performed. The indoor unit 200 may transmit the error code to the mode change control device 300 through the indoor unit communicator 2030. In operation 1295, the indoor unit 200 may control the indoor EEV 220 to be closed to stop the operation of the indoor unit 200. In operation 1297, the mode change control device 300 may control the heating valve 310 and the cooling valve 320 to be closed to stop the operation of the mode change control device 300, based on the error code received from the indoor unit 200 through the central communicator 3030. In operation 1299, the indoor unit 200 may output the error code through an output interface included in the indoor unit 200. For example, the error code may be displayed on a display of the indoor unit 200, but is not limited thereto.

For example, the air conditioner 1000 may open the heating main valve 410 of FIG. 4A, the cooling EEV 620 of FIG. 6A, or the cooling main valve 820 of FIG. 8A for the heating operation, only when the pressure equalization control has been normally performed. Accordingly, noise, vibration, and an impact may be prevented/avoided from being generated in the air conditioner 1000.

FIG. 13 is a signal flow diagram illustrating an example method of detecting a pressure equalization control error when an air conditioner switches from a heating operation to a cooling operation, according to various embodiments. FIG. 13 will be described with reference to FIG. 10.

Referring to FIG. 13, in operation 1310, the indoor unit 200 and the mode change control device 300 may perform the heating operation. For example, operation 1310 may include operation 1313 and operation 1317. In operation 1313, the indoor unit 200 may control the indoor EEV 220 to be opened for the heating operation. In operation 1317, the mode change control device 300 may control the heating valve 310 to be opened for the heating operation.

Operation 1310 may correspond to at least one of the heating operation process (operation 501) of FIG. 5A, the heating operation process (operation 701) of FIG. 7A, or the heating operation process (operation 901) of FIG. 9A. The heating valve 310 may correspond to at least one of the heating main valve 410 of FIG. 5A, the heating EEV 610 of FIG. 7A, or the heating main valve 810 of FIG. 9A. The cooling valve 320 may correspond to at least one of the cooling main valve 420 of FIG. 4A, the cooling EEV 620 of FIG. 6A, or the cooling main valve 820 of FIG. 8A. Operation 1310 may correspond to operation 1110 of FIG. 11.

In operation 1320, the indoor unit 200 may receive the user input corresponding to the operating mode switch command. For example, when a cooling operation setting input is received while the heating operation is performed, the indoor unit 200 may generate a control signal for performing a switch operation from the heating operation to the cooling operation. In operation 1325, the indoor unit 200 may transmit the control signal corresponding to the operating mode switch command to the mode change control device 300 through the indoor unit communicator 2030. The mode change control device 300 may receive the control signal corresponding to the operating mode switch command from the indoor unit 200 through the central communicator 3030.

In operation 1330, the indoor unit 200 and the mode change control device 300 may stop the heating operation, based on the user input corresponding to the operating mode switch command. For example, operation 1330 may include operation 1333 and operation 1337. In operation 1333, the indoor unit 200 may control the indoor EEV 220 to be closed to stop the heating operation. In operation 1337, the mode change control device 300 may control the heating valve 310 to be closed to stop the heating operation.

Here, operations 1320 and 1330 may correspond to operation 1120 of FIG. 11.

In operation 1340, the indoor unit 200 may detect the first temperature of the indoor heat exchanger. The first temperature may be the first time point refrigerant temperature.

In operation 1350, the indoor unit 200 and the mode change control device 300 may perform the pressure equalization control for low pressurization of the refrigerant of the indoor unit 200. The air conditioner 1000 may decrease the refrigerant pressure in the high-pressure section formed at the second side (the indoor unit 200) of the cooling valve 320 to reduce the refrigerant pressure difference between the low-pressure section and the high-pressure section formed at opposite sides of the cooling valve 320.

For example, referring to the pressure equalization process (operation 503) of FIG. 5A, when the cooling sub valve 430 is used as a pressure equalization EEV for switching from the heating operation to the cooling operation, the mode change control device 300 may open the cooling sub valve 430 while the heating main valve 410 and the cooling main valve 420 are in closed states. The air conditioner 1000 may open the cooling sub valve 430 to decrease the refrigerant pressure of the high-pressure section formed at the second side (side at the indoor unit 200) of the cooling main valve 420.

For example, referring to the pressure equalization process (operation 703) of FIG. 7A, when the cooling EEV 620 is used as a pressure equalization EEV for switching from the heating operation to the cooling operation, the mode change control device 300 may control the cooling EEV 620 to be opened to a minimum opening degree. The air conditioner 1000 may open the cooling EEV 620 to a minimum opening degree to decrease the refrigerant pressure of the high-pressure section formed at the second side (side at the indoor unit 200) of the cooling EEV 620.

For example, referring to the pressure equalization process (operation 903) of FIG. 9A, when the cooling sub valve 840 is used as a pressure equalization EEV for switching from the heating operation to the cooling operation, the mode change control device 300 may control the cooling sub valve 840 to be opened while the heating main valve 810 and the cooling main valve 820 are in closed states. The air conditioner 1000 may open the cooling sub valve 840 to decrease the refrigerant pressure of the high-pressure section formed at the second side (side at the indoor unit 200) of the cooling main valve 420.

In operation 1360, the indoor unit 200 may detect the second temperature of the indoor heat exchanger. The second temperature may be the second time point refrigerant temperature.

In operation 1370, the indoor unit 200 may determine whether a range of a temperature decrease between the first time point refrigerant temperature and the second time point refrigerant temperature is greater than the defined value. For example, when the refrigerant pressure has been normally changed according to the pressure equalization control, the second time point refrigerant temperature may be lower than the first time point refrigerant temperature by about 20° C. In this case, the defined value may be about 15° C. The indoor unit 200 may determine that the pressure equalization control has been normally performed when the range of the temperature decrease between the first time point refrigerant temperature and the second time point refrigerant temperature is greater than 15° C.

Operations 1340 to 1370 may correspond to operations 1130 and 1140 of FIG. 11.

In operation 1380, the indoor unit 200 may determine that the pressure equalization control has been normally performed when the range of the temperature decrease between the first time point refrigerant temperature and the second time point refrigerant temperature is greater than the defined value, and perform the cooling operation. For example, operation 1380 may include operation 1383 and operation 1387. In operation 1383, the indoor unit 200 may control the indoor EEV 220 to be opened to perform the cooling operation. The indoor unit 200 may generate a control signal for performing the cooling operation and transmit the control signal to the mode change control device 300, but the disclosure is not limited thereto. In operation 1387, the mode change control device 300 may control the cooling valve 320 to be opened to perform the cooling operation. For example, the mode change control device 300 may control the cooling valve 320 to be opened, based on receiving the control signal for performing the cooling operation.

In operation 1390, the indoor unit 200 may determine that the pressure equalization control has not been normally performed when the range of the temperature decrease between the first time point refrigerant temperature and the second time point refrigerant temperature is equal to or lower than the defined value, and stop the operation. For example, operations 1393, 1395, 1397, and 1399 may respectively correspond to operations 1293, 1295, 1297, and 1299 of FIG. 12.

For example, the air conditioner 1000 may open the cooling main valve 420 of FIG. 5A, the cooling EEV 620 of FIG. 7A, or the cooling main valve 820 of FIG. 9A for the cooling operation, only when the pressure equalization control has been normally performed. Accordingly, noise, vibration, and an impact may be prevented/avoided from being generated in the air conditioner 1000.

Operation 1380 may correspond to operation 1150 of FIG. 11, and operation 1390 may correspond to operation 1160 of FIG. 11.

FIG. 14 is a diagram illustrating an example operation in which an air conditioner obtains an operating mode switch command, according to various embodiments. FIG. 14 may correspond to operations of the air conditioner according to operation 1120 of FIG. 11.

An air conditioning system according to an embodiment of the disclosure may include a remote controller 400-1, an indoor unit 200-1, the mode change control device 300, and the outdoor unit 100. The remote controller 400-1 may be an input device connected to the indoor unit 200-1. The air conditioning system may include a plurality of remote controllers 400-1 configured to respectively control a plurality of indoor units.

The remote controller 400-1 may include an input device configured to receive various control commands from a user, and a device configured to remotely control at least one of components of the air conditioner 1000 according to a received control command. For example, the remote controller 400-1 may include a button, a key, a pad, a touchscreen, or the like. For example, the remote controller 400-1 may be a remote controller connected to the indoor unit 200-1 through a wired/wireless communication network. The remote controller 400-1 may be a user terminal. Examples of the user terminal include a smartphone and a glasses- or watch-type wearable device, but are not limited thereto.

The remote controller 400-1 may receive a user input corresponding to an operating mode switch command to switch a first operation to a second operation. The user input corresponding to the operating mode switch command may include an operating mode setting input of selecting a cooling operation or a heating operation, or an indoor temperature setting input of setting an indoor temperature. For example, the remote controller 400-1 may include a heating user interface (UI) 1401, a cooling UI 1402, or an indoor temperature control UI 1403. The remote controller 400-1 may receive the user input corresponding to the operating mode switch command through each UI.

The remote controller 400-1 may receive the operating mode setting input and transmit the operating mode setting input to the indoor unit 200-1 (operation 1410). The remote controller 400-1 may transmit the indoor temperature setting input to the indoor unit 200-1 (operation 1420).

The indoor unit 200-1 may receive the user input corresponding to the operating mode switch command from the remote controller 400-1 through the indoor unit communicator 2030 (FIG. 10). Alternatively, for example, the indoor unit 200-1 may receive the user input corresponding to the operating mode switch command through an input interface included in the indoor unit 200-1.

For example, when a heating operation setting input is received while the cooling operation is performed, the indoor unit 200-1 may generate a control signal for performing a switch operation from the cooling operation to the heating operation. For example, when a cooling operation setting input is received while the heating operation is performed, the indoor unit 200-1 may generate a control signal corresponding to a switch operation from the heating operation to the cooling operation. The indoor unit 200-1 may transmit the control signal corresponding to the operating mode switch command to the mode change control device 300 or the outdoor unit 100 (operation 1450).

For example, upon receiving the indoor temperature setting input from the remote controller 400-1, the indoor unit 200-1 may compare a current indoor temperature with a set temperature (operation 1430), and determine whether to switch an operating mode (operation 1440). For example, the indoor unit 200-1 may determine to switch from the cooling operation to the heating operation when the indoor temperature setting input (e.g., 30° C.) higher than the current indoor temperature (e.g., 23° C.) is received during the cooling operation. For example, the indoor unit 200-1 may determine to switch from the heating operation to the cooling operation when the indoor temperature setting input (e.g., 18° C.) lower than the current indoor temperature (e.g., 26° C.) is received during the heating operation. The indoor unit 200-1 may generate the control signal corresponding to the operating mode switch command and transmit the control signal to the mode change control device 300 or the outdoor unit 100 (operation 1450).

FIG. 15 is a flowchart for illustrating an example method of detecting a pressure equalization control error when switching an operating mode of an air conditioner, according to various embodiments.

FIG. 15 differs from FIG. 11 in that the air conditioner 1000 according to an embodiment of the disclosure further performs an operation of determining an error when a same symptom occurs n times, without immediately determining an error, when a temperature change does not reach a defined value after the pressure equalization control. A pressure equalization control error may be further accurately detected when the air conditioner 1000 according to an embodiment of the disclosure is used.

In operation 1510, the air conditioner 1000 may perform the first operation. This corresponds to operation 1110 of FIG. 11.

In operation 1520, the air conditioner 1000 may stop the first operation based on the operating mode switch command to switch from the first operation to the second operation. This corresponds to operation 1120 of FIG. 11.

In operation 1530, the air conditioner 1000 may perform the pressure equalization control while the first operation is stopped. This corresponds to operation 1130 of FIG. 11.

In operation 1540, the air conditioner 1000 may determine whether a temperature change between the first temperature and the second temperature corresponds to a defined value. This may be an example of a method by which the air conditioner 1000 determines whether the refrigerant pressure difference of the opposite sides of the transfer valve has been reduced, in operation 1140. The first temperature may be the first time point refrigerant temperature and the second temperature may be the second time point refrigerant temperature.

In operation 1550, the air conditioner 1000 may identify whether a same situation has occurred n times (e.g., 3 times) or more, when the temperature change is equal to or less than the defined value. Here, n may be a natural number.

In operation 1560, when it is determined that a situation in which the temperature change is identified to be equal to or less than the defined value has occurred n times or more, the air conditioner 1000 may transmit an error code and stop the operation.

In operation 1570, when it is determined that the situation in which the temperature change is equal to or less than the defined value has occurred less than n times or when the temperature change is greater than the defined value, the air conditioner 1000 may perform the second operation.

FIG. 16 is a block diagram illustrating an example configuration of an air conditioner according to various embodiments.

Referring to FIG. 16, an air conditioner 1600 according to an embodiment of the disclosure may include an outdoor unit 1630, an indoor unit 1640, a mode change control device (e.g., including a valve) 1650, an input/output interface (e.g., including circuitry) 1660, a communicator (e.g., including communication circuitry) 1670, a sensor 1680, a processor (e.g., including processing circuitry) 1610, and a memory 1620. However, not all of the components shown in FIG. 16 are essential components. The air conditioner 1600 may be implemented by more or fewer components than those illustrated in FIG. 16.

Some or all operations of the processor 1610 of FIG. 16 may be performed by the central processor 3010 of the mode change control device 300 of FIG. 10, performed by the indoor unit processor 2010 of the indoor unit 200, or performed by the outdoor unit processor 1010 of the outdoor unit 100.

All components of a heat pump device may be accommodated in a single housing configuring the exterior of the air conditioner 1600, and a window-type air conditioner or a portable air conditioner corresponds to such an air conditioner 1600. On the other hand, some components of the heat pump device may be divided and accommodated in a plurality of housings configuring a single air conditioner 1600, including a wall-mounted air conditioner, a stand-alone air conditioner, or a system air conditioner.

The air conditioner 1600 including the plurality of housings may include at least one outdoor unit 1630 provided outdoors, and at least one indoor unit 1640 provided indoors. For example, the air conditioner 1600 may be provided such that one outdoor unit 1630 and one indoor unit 1640 are connected to each other through a refrigerant pipe. For example, the air conditioner 1600 may be provided such that one outdoor unit 1630 is connected to two or more indoor units 1640 through a refrigerant pipe. For example, the air conditioner 1600 may be provided such that two or more outdoor units 1630 are connected to tow or more indoor units 1640 through a refrigerant pipe.

The outdoor unit 1630, the indoor unit 1640, and the mode change control device 1650 may be electrically connected to each other. For example, an input interface 1662 may be provided in at least one of the outdoor unit 1630, the indoor unit 1640, or the mode change control device 1650, and a user may input information (or a command) for controlling the air conditioner 1600 through the input interface 1662. The outdoor unit 1630, the indoor unit 1640, and the mode change control device 1650 may simultaneously or sequentially operate in response to a user input.

The air conditioner 1600 may include an outdoor heat exchanger 1635 included in the outdoor unit 1630, and an indoor heat exchanger 1645 included in the indoor unit 1640. The outdoor heat exchanger 1635 may correspond to the outdoor heat exchanger 120 of FIG. 2A. The indoor heat exchanger 1645 may correspond to the indoor heat exchanger 210 of FIG. 2A. The outdoor heat exchanger 1635 or the indoor heat exchanger 1645 may correspond to an evaporator or a condenser.

The indoor unit 1640 is provided indoors. For example, the indoor unit 1640 may be classified into a ceiling-type indoor unit, a stand-type indoor unit, a wall-mounted indoor unit, or the like depending on a method of placement. For example, a ceiling-type indoor unit may be classified into a 4-way indoor unit, a 1-way indoor unit, or a duct-type indoor unit depending on a method by which air is discharged.

For example, when one outdoor unit 1630 and one indoor unit 1640 are directly connected to each other through a refrigerant pipe, the air conditioner 1600 may be provided such that a refrigerant circulates between the one outdoor unit 1630 and the one indoor unit 1640 through the refrigerant pipe.

For example, when one outdoor unit 1630 is connected to two or more indoor units 1640 through one mode change control device 1650, the air conditioner 1600 may be provided such that a refrigerant flows to the plurality of indoor units 1640 through refrigerant pipes branched from the mode change control device 1650. The refrigerant discharged from the plurality of indoor units 1640 may join and circulate to the outdoor unit 1630. For example, the plurality of indoor units 1640 may be directly connected to one mode change control device 1650 and the outdoor unit 1630 in parallel, through separate refrigerant pipes.

The plurality of indoor units 1640 may operate independently according to operating modes set by a user. In other words, some of the plurality of indoor units 1640 may operate in a cooling mode and at the same time, others may operate in a heating mode. The refrigerant selectively in a high-pressure state or a low-pressure state may be introduced to each indoor unit 1640 according to a designated circulation path through a flow path switch valve, and may be discharged and circulate to the outdoor unit 1630.

For example, when two or more outdoor units 1630 and two or more indoor units 1640 are connected to each other through a plurality of refrigerant pipes, the air conditioner 1600 may be provided such that refrigerants discharged from the plurality of outdoor units 1630 may join and flow through one refrigerant pipe, and then may be introduced to the plurality of indoor units 1640 by being branched at a specific point.

The plurality of outdoor units 1630 and plurality of indoor units 1640 may operate or at least some of the plurality of outdoor units 1630 and plurality of indoor units 1640 may not operate depending on operating loads according to operating amounts. Here, the refrigerant may circulate after being introduced to the outdoor unit 1630 that is selectively driven, through the flow path switch valve. The air conditioner 1600 may include an expansion valve to decrease a pressure of a refrigerant introduced to a heat exchanger. For example, the expansion valve may be provided inside the indoor unit 1640, inside the outdoor unit 1630, or inside both the indoor unit 1640 and the outdoor unit 1630. The expansion valve may correspond to the indoor EEV 220 of FIG. 2A.

The air conditioner 1600 may further include the flow path switch valve arranged on a refrigerant circulation flow path. The flow path switch valve may include, for example, a 4-way valve. The flow path switch valve may determine a circulation path of the refrigerant, depending on an operating mode (e.g., a cooling operation or a heating operation) of the indoor unit 1640. The flow path switch valve may be connected to a discharge unit of the compressor.

The air conditioner 1600 may include an accumulator. The accumulator may be connected to a suction unit of the compressor. A low-temperature low-pressure refrigerant evaporated from the indoor heat exchanger 1645 or the outdoor heat exchanger 1635 may be introduced to the accumulator. When a refrigerant in which a refrigerant liquid and a refrigerant gas are mixed is introduced, the accumulator may separate the refrigerant liquid from the refrigerant gas and provide, to the compressor, the refrigerant gas from which the refrigerant liquid has been separated.

An outdoor fan may be provided near the outdoor heat exchanger 1635. The outdoor fan may blow outdoor air to the outdoor heat exchanger 1635 such that heat exchange between the refrigerant and the outdoor air is promoted.

The indoor unit 1640 of the air conditioner 1600 may include a housing, a blower circulating air to the inside or outside the housing, and the indoor heat exchanger 1645 configured to exchange heat with air introduced into the housing.

The housing may include a suction hole. Indoor air may be introduced into the housing through the suction hole.

The indoor unit 1640 of the air conditioner 1600 may include a filter provided to filter out foreign substances in air introduced into the housing through the suction hole.

The housing may include a discharge hole. Air flowing inside the housing may be discharged outside the housing through the discharge hole.

The housing of the indoor unit 1640 may include an air current guide to guide a direction of the air discharged through the discharge hole. For example, the air current guide may include a blade located on the discharge hole. For example, the air current guide may include an auxiliary fan to control a discharged air current. However, the disclosure is not limited thereto, and the air current guide may be omitted.

The indoor heat exchanger 1645 and the blower, which are arranged on a flow path connecting the suction hole and the discharge hole, may be provided inside the housing of the indoor unit 1640.

The blower may include an indoor fan and a fan motor. Examples of the indoor fan may include an axial fan, a radial fan, a crossflow fan, and a centrifugal fan.

The indoor heat exchanger 1645 may be provided between the blower and the discharge hole, or may be provided between the suction hole and the blower. The indoor heat exchanger 1645 may absorb heat from air introduced through the suction hole or may transfer heat to the air introduced through the suction hole. The indoor heat exchanger 1645 may include a heat exchange pipe in which a refrigerant flows, and a heat exchange pin in contact with the heat exchange pipe to increase a heat transfer area.

The indoor unit 1640 of the air conditioner 1600 may include a drain tray arranged below the indoor heat exchanger 1645 and collecting condensate generated in the indoor heat exchanger 1645. The condensate accommodated in the drain tray may be drained to the outside through a drain hose. The drain tray may be provided to support the indoor heat exchanger 1645.

The indoor unit 1640 of the air conditioner 1600 may include a power module. The power module may be connected to an external power source to supply power to the components of the indoor unit 1640.

For example, the outdoor unit 1630 may adjust a frequency of the compressor and control the flow path switch valve to switch a circulation direction of the refrigerant. The outdoor unit 1630 may control a rotating speed of an outdoor circulation fan. Also, the outdoor unit 1630 may generate a control signal for controlling an opening degree of the expansion valve.

The communicator 1670 may include one or more components including circuitry configured to perform communication between the outdoor unit 1630, the indoor unit 1640, and the mode change control device 1650. For example, the communicator 1670 may include a port connecting a wired cable performing wired communication between the outdoor unit 1630, the indoor unit 1640, and the mode change control device 1650. Also, for example, the communicator 1670 may include at least one antenna for communicating with an external device wirelessly. For example, the communicator 1670 may include a short-range wireless communication module or a long-range communication module. The short-range wireless communication module may include a Bluetooth communication module, a Bluetooth low energy (BLE) communication module, a near field communication module, a wireless local area network (WLAN) (Wi-Fi) communication module, a Zigbee communication module, an Infrared Data Association (IrDA) communication module, a Wi-Fi direct (WFD) communication module, an ultra-wideband (UWB) communication module, and an Ant+ communication module, but is not limited thereto.

For example, the communicator 1670 may communicate with an external device, such as a server, a mobile device, or another home appliance, through a nearby access point (AP). The AP may connect a local area network (LAN) to which the air conditioner 1600 or a user device is connected to a wide area network (WAN) to which a server is connected. The air conditioner 1600 or the user device may be connected to the server through the WAN.

For example, the communicator 1670 included in the outdoor unit 1630 may correspond to the outdoor unit communicator 1030. The communicator 1670 included in the indoor unit 1640 may correspond to the indoor unit communicator 2030. The communicator 1670 included in the mode change control device 1650 may correspond to the central communicator 3030 of FIG. 10.

The sensor 1680 may include an environmental sensor arranged in a space inside or outside the housing. Each of the outdoor unit 1630, the indoor unit 1640, and the mode change control device 1650 may include at least one sensor arranged at any internal or external location. The sensor 1680 may include a temperature sensor 1682, a humidity sensor configured to detect ambient air humidity, a refrigerant temperature sensor 1684 configured to detect a temperature of a refrigerant in the refrigerant pipe, or a refrigerant pressure sensor 1686 configured to detect a pressure of the refrigerant in the refrigerant pipe.

The memory 1620 may store various types of information required for operations of the air conditioner 1600. The memory 1620 may store an instruction, an application, data, and/or a program required for operations of the air conditioner 1600. For example, the memory 1620 may store various programs for a cooling operation, a heating operation, a dehumidification operation, and/or a defrosting operation of the air conditioner 1600. The memory 1620 may include a volatile memory, such as static random-access memory (S-RAM) or dynamic random-access memory (D-RAM), to temporarily store data. Also, the memory 1620 may include a non-volatile memory, such as read-only memory (ROM), erasable programmable read-only memory (EPROM), or electrically erasable programmable read-only memory (EEPROM), for long-term storage of data. Programs stored in the memory 1620 may be classified into a plurality of modules depending on functions.

The processor 1610 may include various processing circuitry and generate a control signal to control operations of the air conditioner 1600, based on an instruction, an application, data, and/or a program stored in the memory 1620. The processor 1610 is hardware and may include a logic circuit and an arithmetic circuit. The processor 1610 may process data according to a program and/or an instruction provided from the memory 1620, and generate the control signal according to a result of the processing. The memory 1620 and the processor 1610 may be implemented as one control circuit or a plurality of circuits. The processor 1610 may include at least one processor.

The at least one processor may be a circuitry such as a system-on-chip (SoC) or an integrated circuit (IC). The at least one processor included in the processor 1610 may include a general-purpose processor, such as a central processing unit (CPU), a micro-processor unit (MPU), an application processor (AP), or a digital signal processor (DSP), a graphics dedicated processor, such as a graphics processing unit (GPU) or a vision processing unit (VPU), an artificial intelligence dedicated processor, such as a neural processing unit (NPU), or a communication dedicated processor, such as a communication processor (CP).

Each of the outdoor unit 1630, the indoor unit 1640, and the mode change control device 1650 may include the processor 1610 and the memory 1620. For example, the processor 1610 and the memory 1620 included in the outdoor unit 1630 may respectively correspond to the outdoor unit processor 1010 and the outdoor unit memory 1020 of FIG. 10. The processor 1610 and the memory 1620 included in the indoor unit 1640 may respectively correspond to the indoor unit processor 2010 and the indoor unit memory 2020 of FIG. 10. The processor 1610 and the memory 1620 included in the mode change control device 1650 may respectively correspond to the central processor 3010 and the central memory 3020 of FIG. 10.

The indoor unit 1640 of the air conditioner 1600 may include the input interface 1662. The input interface 1662 may include various circuitry including any type of user input unit including a button, a switch, a touchscreen, and/or a touch pad. The user may directly input setting data (e.g., a desired indoor temperature, an operating mode setting for cooling/heating/dehumidification/air purification, an outlet selection setting, and/or a wind speed setting) through the input interface 1662.

The input interface 1662 may be connected to an external input device. For example, the input interface 1662 may be electrically connected to a wired remote controller. The wired remote controller may be provided at a specific location (e.g., a portion of a wall) of an indoor space. The user may input setting data related to an operation of the air conditioner 1600 by manipulating the wired remote controller. An electrical signal corresponding to the setting data obtained through the wired remote controller may be transmitted to the input interface 1662. Also, the input interface 1662 may include an infrared sensor. The user may input the setting data related to the operation of the air conditioner 1600 remotely using a wireless remote controller. The setting data input through the wireless remote controller may be transmitted to the input interface 1662, as an infrared signal.

The input interface 1662 may include a microphone. A speech command of the user may be obtained through the microphone. The microphone may convert the speech command of the user into an electrical signal and transmit the electrical signal to an indoor unit processor. The indoor unit processor may control the components of the air conditioner 1600 to execute a function corresponding to the speech command of the user. The setting data (e.g., a desired indoor temperature, an operating mode setting for cooling/heating/dehumidification/air purification, an outlet selection setting, and/or a wind speed setting) obtained through the input interface 1662 may be transmitted to the indoor unit processor described below. For example, the setting data obtained through the input interface 1662 may be transmitted to the outside, e.g., the outdoor unit 1630, the mode change control device 1650, or the server, through an indoor unit communicator.

For example, an output interface 1664 may be provided in the indoor unit 1640 of the air conditioner 1600. The output interface 1664 may be electrically connected to the indoor unit processor and output information related to an operation of the air conditioner 1600 under control by the indoor unit processor. For example, information, such as an operating mode, a wind direction, a wind speed, and a temperature, selected by a user input may be output. Also, the output interface 1664 may output sensing information and a warning/error message obtained from an indoor unit sensor or an outdoor unit sensor.

The output interface 1664 may include a display and a speaker. The speaker is an audio device and may output various types of sound. The display may display information input by the user or information provided to the user, using various graphic elements. For example, operation information of the air conditioner 1600 may be displayed as at least one of an image or text. Also, the display may include an indicator providing specific information.

According to an embodiment of the disclosure, a control method for an air conditioner, includes performing a first operation corresponding to one of a cooling operation or a heating operation, stopping the first operation based on a switch command to switch from the first operation to a second operation corresponding to the other one of the cooling operation or the heating operation, while the first operation is stopped, performing pressure equalization control so that a refrigerant pressure difference of opposite sides of a transfer valve for the second operation is reduced, determining whether the refrigerant pressure difference has been reduced based on the pressure equalization control, and based on a result of the determination, determining whether to perform the second operation.

According to an embodiment of the disclosure, the mode change control device may include a cooling valve and a heating valve, the performing of the pressure equalization control while the first operation is stopped may include, when the first operation is the cooling operation, adjusting a refrigerant pressure of a low-pressure section while the cooling operation is stopped, so that a pressure difference between a high-pressure section corresponding to a first side of the heating valve and the low-pressure section corresponding to a second side of the heating valve is reduced, and when the first operation is the heating operation, adjusting a refrigerant pressure of a high-pressure section while the heating operation is stopped, so that a pressure difference between a low-pressure section corresponding to the first side of the cooling valve and the high-pressure section corresponding to the second side of the cooling valve is reduced, and the first side may correspond to the outdoor unit and the second side may correspond to an indoor unit.

According to an embodiment of the disclosure, the mode change control device may include a heating main valve corresponding to the heating valve, a cooling main valve corresponding to the cooling valve, and a cooling sub valve, the adjusting of the refrigerant pressure of the low-pressure section while the cooling operation is stopped may include controlling an opening degree to open an indoor electronic expansion valve (EEV) included in the indoor unit, so as to increase a refrigerant pressure of a low-pressure section corresponding to the second side of the heating main valve, and the adjusting of the refrigerant pressure of the high-pressure section while the heating operation is stopped may include controlling an opening degree to open the cooling sub valve included in the mode change control device, so as to decrease a refrigerant pressure of a high-pressure section corresponding to the second side of the cooling main valve.

According to an embodiment of the disclosure, the mode change control device may include a heating EEV corresponding to the heating valve and a cooling EEV corresponding to the cooling valve, the adjusting of the refrigerant pressure of the low-pressure section while the cooling operation is stopped may include controlling the heating EEV to be opened to a minimum opening degree, so as to increase a refrigerant pressure of a low-pressure section corresponding to the second side of the heating EEV, and the adjusting of the refrigerant pressure of the high-pressure section while the heating operation is stopped may include controlling the cooling EEV to be opened to a minimum opening degree, so as to decrease a refrigerant pressure of a high-pressure section corresponding to the second side of the cooling EEV.

According to an embodiment of the disclosure, the mode change control device may include a heating main valve corresponding to the heating valve, a cooling main valve corresponding to the cooling valve, a heating sub valve, and a cooling sub valve, the adjusting of the refrigerant pressure of the low-pressure section while the cooling operation is stopped may include controlling the heating sub valve to be opened so as to increase a refrigerant pressure of a low-pressure section corresponding to the second side of the heating main valve, and the adjusting of the refrigerant pressure of the high-pressure section while the heating operation is stopped may include controlling the cooling sub valve to be opened so as to decrease a refrigerant pressure of a high-pressure section corresponding to the second side of the cooling main valve.

According to an embodiment of the disclosure, an indoor unit may include an indoor heat exchanger and a refrigerant temperature sensor configured to sense a temperature of a refrigerant pipe passing through the indoor heat exchanger, the determining of whether the refrigerant pressure difference has been reduced may include obtaining a first time point refrigerant temperature before the pressure equalization control is performed, via the refrigerant temperature sensor, obtaining a second time point refrigerant temperature after the pressure equalization control is performed, via the refrigerant temperature sensor, and determining whether a temperature difference between the first time point refrigerant temperature and the second time point refrigerant temperature corresponds to a set condition, and the determining of whether to perform the second operation based on the result of the determination may include performing the second operation based on determining that the temperature difference corresponds to the set condition, and stopping the first operation and the second operation based on determining that the temperature difference does not correspond to the set condition.

According to an embodiment of the disclosure, the determining of whether to perform the second operation based on the result of the determination may include performing the second operation based on determining that the refrigerant pressure difference has been reduced, and stopping the first operation and the second operation and transmitting an error code from an indoor unit to the mode change control device, based on determining that the refrigerant pressure difference has not been reduced.

According to an embodiment of the disclosure, the determining of whether to perform the second operation based on the result of the determination may include displaying the error code on a display of the plurality of indoor units, based on determining that the refrigerant pressure difference has not been reduced.

According to an embodiment of the disclosure, the control method may further include receiving, from a user through an input interface included in the air conditioner, an operating mode setting input of selecting the cooling operation or the heating operation, or an indoor temperature setting input of setting an indoor temperature, and transmitting a control signal corresponding to the switch command from an indoor unit to the mode change control device, based on a setting input received from the user.

According to an embodiment of the disclosure, an air conditioner includes an outdoor unit, a plurality of indoor units connected to the outdoor unit, a mode change control device connecting the outdoor unit to the plurality of indoor units and configured to switch between a cooling operation and a heating operation of each of the plurality of indoor units, a memory including at least one storage medium storing one or more instructions, and at least one processor including a processing circuit.

When the one or more instructions are individually or collectively executed by the at least one processor according to an embodiment of the disclosure, the air conditioner may perform a first operation corresponding to one of a cooling operation or a heating operation. When the one or more instructions are individually or collectively executed by the at least one processor according to an embodiment of the disclosure, the air conditioner may stop the first operation based on a switch command to switch from the first operation to a second operation corresponding to the other one of the cooling operation or the heating operation. The air conditioner according to an embodiment of the disclosure may, while the first operation is stopped, perform pressure equalization control so that a refrigerant pressure difference of opposite sides of a transfer valve for the second operation is reduced. The air conditioner according to an embodiment of the disclosure may determine whether the refrigerant pressure difference has been reduced based on the pressure equalization control. The air conditioner according to an embodiment of the disclosure may determine whether to perform the second operation based on a result of the determination.

According to an embodiment of the disclosure, the mode change control device may include a cooling valve and a heating valve, and when the one or more instructions are individually or collectively executed by the at least one processor, the air conditioner may, when the first operation is the cooling operation, adjusts a refrigerant pressure of a low-pressure section while the cooling operation is stopped, so that a pressure difference between a high-pressure section corresponding to a first side of the heating valve and the low-pressure section corresponding to a second side of the heating valve is reduced. According to an embodiment of the disclosure, the air conditioner may, when the first operation is the heating operation, adjusts a refrigerant pressure of a high-pressure section while the heating operation is stopped, so that a pressure difference between a low-pressure section corresponding to the first side of the cooling valve and the high-pressure section corresponding to the second side of the cooling valve is reduced. The first side may correspond to the outdoor unit and the second side may correspond to an indoor unit.

According to an embodiment of the disclosure, the mode change control device may include a heating main valve corresponding to the heating valve, a cooling main valve corresponding to the cooling valve, and a cooling sub valve, and when the one or more instructions are individually or collectively executed by the at least one processor, the air conditioner may control an opening degree to open an indoor electronic expansion valve (EEV) included in the indoor unit, so as to increase a refrigerant pressure of a low-pressure section corresponding to the second side of the heating main valve. According to an embodiment of the disclosure, when the one or more instructions are individually or collectively executed by the at least one processor, the air conditioner may control an opening degree to open the cooling sub valve included in the mode change control device, so as to decrease a refrigerant pressure of a high-pressure section corresponding to the second side of the cooling main valve.

According to an embodiment of the disclosure, the mode change control device may include a heating EEV corresponding to the heating valve and a cooling EEV corresponding to the cooling valve, and when the one or more instructions are individually or collectively executed by the at least one processor, the air conditioner may control the heating EEV to be opened to a minimum opening degree, so as to increase a refrigerant pressure of a low-pressure section corresponding to the second side of the heating EEV. According to an embodiment of the disclosure, the air conditioner may control the cooling EEV to be opened to a minimum opening degree, so as to decrease a refrigerant pressure of a high-pressure section corresponding to the second side of the cooling EEV.

According to an embodiment of the disclosure, the mode change control device may include a heating main valve corresponding to the heating valve, a cooling main valve corresponding to the cooling valve, a heating sub valve, and a cooling sub valve, and when the one or more instructions are individually or collectively executed by the at least one processor, the air conditioner may control the heating sub valve to be opened so as to increase a refrigerant pressure of a low-pressure section corresponding to the second side of the heating main valve. According to an embodiment of the disclosure, the air conditioner may control the cooling sub valve to be opened so as to decrease a refrigerant pressure of a high-pressure section corresponding to the second side of the cooling main valve.

According to an embodiment of the disclosure, an indoor unit may include an indoor heat exchanger and a refrigerant temperature sensor configured to sense a temperature of a refrigerant pipe passing through the indoor heat exchanger, and when the one or more instructions are individually or collectively executed by the at least one processor, the air conditioner may obtain a first time point refrigerant temperature before the pressure equalization control is performed, via the refrigerant temperature sensor, obtain a second time point refrigerant temperature after the pressure equalization control is performed, via the refrigerant temperature sensor, and determine whether a temperature difference between the first time point refrigerant temperature and the second time point refrigerant temperature corresponds to a set condition. According to an embodiment of the disclosure, the air conditioner may perform the second operation based on determining that the temperature difference corresponds to the set condition, and stop the first operation and the second operation based on determining that the temperature difference does not correspond to the set condition.

According to an embodiment of the disclosure, when the one or more instructions are individually or collectively executed by the at least one processor, the air conditioner may perform the second operation based on determining that the refrigerant pressure difference has been reduced, and stop the first operation and the second operation and transmits an error code from an indoor unit to the mode change control device, based on determining that the refrigerant pressure difference has not been reduced.

According to an embodiment of the disclosure, when the one or more instructions are individually or collectively executed by the at least one processor, the air conditioner may receive, from a user through an input interface included in the air conditioner, an operating mode setting input of selecting the cooling operation or the heating operation, or an indoor temperature setting input of setting an indoor temperature, and transmit a control signal corresponding to the switch command from an indoor unit to the mode change control device, based on a setting input received from the user.

According to an embodiment of the disclosure, an indoor unit may be provided. The indoor unit connected to an outdoor unit and a mode change control device, may include an indoor heat exchanger, an indoor electronic expansion valve (EEV), an indoor unit communicator, a memory including at least one storage medium storing one or more instructions, and at least one processor including a processing circuit.

According to an embodiment of the disclosure, the indoor unit may perform a first operation corresponding to one of a cooling operation or a heating operation by opening the indoor EEV. According to an embodiment of the disclosure, the indoor unit may obtain a switch command to switch from the first operation to a second operation corresponding to the other one of the cooling operation or the heating operation. According to an embodiment of the disclosure, the indoor unit may stop the first operation by controlling the indoor EEV to be closed, based on the switch command. According to an embodiment of the disclosure, the indoor unit may transmit a control signal corresponding to the switch command to the outdoor unit and the mode change control device through the indoor unit communicator. According to an embodiment of the disclosure, the indoor unit may determine whether a refrigerant pressure difference of opposite sides of a transfer valve for the second operation has been reduced, while the first operation is stopped. According to an embodiment of the disclosure, the indoor unit may determine whether to perform the second operation by opening the indoor EEV, based on a result of the determination.

According to an embodiment of the disclosure, the indoor unit may further include a refrigerant temperature sensor configured to sense a temperature of a refrigerant pipe passing through the indoor heat exchanger, wherein, when the one or more instructions are individually or collectively executed by the at least one processor, the indoor unit may obtain a first time point refrigerant temperature before pressure equalization control is performed, via the refrigerant temperature sensor, obtain a second time point refrigerant temperature after the pressure equalization control is performed, via the refrigerant temperature sensor, determine whether a temperature difference between the first time point refrigerant temperature and the second time point refrigerant temperature corresponds to a set condition, based on determining that the temperature difference corresponds to the set condition, control the indoor EEV to be opened and transmits an error code to the mode change control device through the indoor unit communicator, and based on determining that the temperature difference does not correspond to the set condition, control the indoor EEV to be closed.

A machine-readable storage medium may be provided in the form of a non-transitory storage medium. Here, the “non-transitory storage medium” refers to a tangible device and does not contain a signal (for example, electromagnetic waves). This term does not distinguish a case where data is stored in the storage medium semi-permanently and a case where the data is stored in the storage medium temporarily. For example, the “non-transitory storage medium” may include a buffer where data is temporarily stored.

According to an embodiment of the disclosure, a method according to various embodiments of the disclosure disclosed in the present disclosure may be provided by being included in a computer program product. The computer program products are products that can be traded between sellers and buyers. The computer program product may be distributed in the form of machine-readable storage medium (for example, a compact disc read-only memory (CD-ROM)), or distributed (for example, downloaded or uploaded) through an application store or directly or online between two user devices (for example, smart phones). In the case of online distribution, at least a part of the computer program product (for example, a downloadable application) may be at least temporarily generated or temporarily stored in a machine-readable storage medium, such as a server of a manufacturer, a server of an application store, or a memory of a relay server.

While the disclosure has been illustrated and described with reference to various example embodiments, it will be understood that the various example embodiments are intended to be illustrative, not limiting. It will be further understood by those skilled in the art that various modifications, alternatives and/or variations of the various example embodiments may be made without departing from the true technical spirit and full technical scope of the disclosure, including the appended claims and their equivalents. It will also be understood that any of the embodiment(s) described herein may be used in conjunction with any other embodiment(s) described herein.