AIR-CONDITIONING DEVICE AND METHOD FOR CONTROLLING AIR-CONDITIONING DEVICE

Description

TECHNICAL FIELD

The present disclosure relates to an air conditioning device and a method for controlling an air conditioning device.

BACKGROUND ART

In the related art, in a heat pump type vehicle air conditioning device, in order to prevent frost from forming on an outside heat exchanger, it is known to execute a frost prevention operation of circulating a high-temperature and high-pressure gas discharged from a compressor between a cabin heat exchanger, an accumulator and the compressor without passing through the outside heat exchanger (for example, see PTL 1). PTL 1 discloses that, in a case where a pressure of the outside heat exchanger on a downstream side is lower than a predetermined value, it is determined that a heat exchange capacity of the outside heat exchanger is decreased due to adhesion of frost, and a heat pump operation is performed using a refrigerant circuit in which the outside heat exchanger is not used.

CITATION LIST

Patent Literature

[PTL 1] Japanese Unexamined Patent Application Publication No. 2000-343934

SUMMARY OF INVENTION

Technical Problem

However, in a case where the heat pump operation is performed with the refrigerant circuit in which the outside heat exchanger is not used, as a pressure of a refrigerant flowing from the accumulator into the compressor becomes lower than a desired pressure, a suction density of the refrigerant decreases, and power of the compressor decreases. In addition, as the pressure of the refrigerant flowing from the accumulator into the compressor becomes higher than the desired pressure, the suction density of the refrigerant increases, and torque necessary for operating the compressor at a desired rotation speed increases.

The present disclosure has been devised in view of such circumstances, and an object thereof is to provide an air conditioning device and a method for controlling an air conditioning device that can suppress a decrease in power of a compressor caused by a decrease in a pressure of a refrigerant flowing into a compressor and an increase in torque of the compressor caused by a rise in a pressure of the refrigerant flowing into the compressor.

Solution to Problem

In order to solve the above problems, the present disclosure adopts the following means.

According to an aspect of the present disclosure, there is provided an air conditioning device including a compressor that compresses a refrigerant, a heating unit that heats a heating target with the refrigerant discharged from the compressor, an accumulator that separates a liquid component in the refrigerant sucked by the compressor, a circulation flow path that guides the refrigerant, which has passed through the heating unit, to the accumulator, a bypass flow path that guides the refrigerant discharged from the compressor to the accumulator without passing the refrigerant through the heating unit, a first expansion mechanism that is disposed at the circulation flow path and that expands the refrigerant flowing out from the heating unit, a second expansion mechanism that is disposed at the bypass flow path and that expands the refrigerant discharged from the compressor, and a control unit that controls a first opening degree of the first expansion mechanism and a second opening degree of the second expansion mechanism, in which the control unit in a case where a pressure of the refrigerant sucked by the compressor is lower than a predetermined pressure, controls the first opening degree and the second opening degree such that a proportion of a gas refrigerant in an inflow refrigerant flowing into the accumulator, including the refrigerant expanded by the first expansion mechanism and the refrigerant expanded by the second expansion mechanism, is larger than a proportion of a gas refrigerant in an outflow refrigerant flowing out from the accumulator, and in a case where the pressure of the refrigerant sucked by the compressor is higher than the predetermined pressure, controls the first opening degree and the second opening degree such that a proportion of a liquid refrigerant in the inflow refrigerant is larger than a proportion of a liquid refrigerant in the outflow refrigerant flowing out from the accumulator.

According to another aspect of the present disclosure, there is provided a method for controlling an air conditioning device, in which the air conditioning device includes a compressor that compresses a refrigerant, a heating unit that heats a heating target with the refrigerant discharged from the compressor, an accumulator that separates a liquid component in the refrigerant sucked by the compressor, a circulation flow path that guides the refrigerant, which has passed through the heating unit, to the accumulator, a bypass flow path that guides the refrigerant discharged from the compressor to the accumulator without passing the refrigerant through the heating unit, a first expansion mechanism that is disposed at the circulation flow path and that expands the refrigerant flowing out from the heating unit, and a second expansion mechanism that is disposed at the bypass flow path and that expands the refrigerant discharged from the compressor, the method including a first control step of, in a case where a pressure of the refrigerant sucked by the compressor is lower than a predetermined pressure, controlling a first opening degree of the first expansion mechanism and a second opening degree of the second expansion mechanism such that a proportion of a gas refrigerant in an inflow refrigerant flowing into the accumulator, including the refrigerant expanded by the first expansion mechanism and the refrigerant expanded by the second expansion mechanism, is larger than a proportion of a gas refrigerant in an outflow refrigerant flowing out from the accumulator, and a second control step of, in a case where the pressure of the refrigerant sucked by the compressor is higher than the predetermined pressure, controlling the first opening degree and the second opening degree such that a proportion of a liquid refrigerant in the inflow refrigerant is larger than a proportion of a liquid refrigerant in the outflow refrigerant flowing out from the accumulator.

Advantageous Effects of Invention

According to the present disclosure, the air conditioning device and the method for controlling an air conditioning device that can suppress a decrease in the power of the compressor caused by a decrease in the pressure of the refrigerant flowing into the compressor and an increase in the torque of the compressor caused by a rise in the pressure of the refrigerant flowing into the compressor can be provided.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a refrigerant circuit diagram of a vehicle air conditioning device according to an embodiment of the present disclosure.

FIG. 2 is a refrigerant circuit diagram showing a refrigerant flow during a heat pump heating operation of the vehicle air conditioning device.

FIG. 3 is a refrigerant circuit diagram showing a refrigerant flow during a hot gas heating operation of the vehicle air conditioning device.

FIG. 4 is a flowchart showing an operation during the hot gas heating operation of the vehicle air conditioning device.

FIG. 5 is a flowchart showing an operation during the hot gas heating operation of the vehicle air conditioning device.

FIG. 6 is a Mollier diagram showing a state of a refrigerant during the hot gas heating operation.

FIG. 7 is a refrigerant circuit diagram showing a refrigerant flow during a dehumidification and heating operation of the vehicle air conditioning device.

FIG. 8 is a refrigerant circuit diagram showing a refrigerant flow during a cooling operation of the vehicle air conditioning device.

DESCRIPTION OF EMBODIMENTS

Hereinafter, a heat pump type vehicle air conditioning device (air conditioning device) 100 according to an embodiment of the present disclosure will be described with reference to FIG. 1. As shown in FIG. 1, the vehicle air conditioning device 100 according to the present embodiment includes a compressor 10, a heating unit 20, an accumulator 30, an expansion valve (first expansion mechanism) 40, an expansion valve (second expansion mechanism) 50, an on-off valve (switching unit) 61, an on-off valve (switching unit) 62, an on-off valve 63, an on-off valve (first on-off valve) 64, an on-off valve (second on-off valve) 65, an expansion valve (third expansion mechanism) 70, an outside heat exchanger 80, an outside fan 81, a cabin heat exchanger (evaporator) 85, a cabin blower 86, a control unit 90, a refrigerant heating heater 91, a pressure sensor 92, a temperature sensor 93, a temperature sensor 94, a temperature sensor 95, and a pressure sensor 96.

The vehicle air conditioning device 100 according to the present embodiment is a device that generates warm air with the heating unit 20 installed in a vehicle or that generates cold air with the cabin heat exchanger 85 installed in the vehicle, and that blows air into the vehicle. The vehicle air conditioning device 100 operates the outside heat exchanger 80 as an evaporator during a heat pump heating operation and operates the outside heat exchanger 80 as a condenser during a cooling operation. In addition, in a case where an outside air temperature is equal to or lower than a predetermined temperature (for example, −20° C.), the vehicle air conditioning device 100 can perform a hot gas heating operation of performing heating using only the power of the compressor 10 without passing a refrigerant through the outside heat exchanger 80. The refrigerant used in the vehicle air conditioning device 100 of the present embodiment is, for example, HFO-1234yf.

The compressor 10 is a device that compresses a refrigerant flowing in from the accumulator 30. The compressor 10 is, for example, a power compressor that drives a motor (not shown) to compress the refrigerant. The compressor 10 compresses a refrigerant flowing in from a refrigerant pipe L1 and discharges the refrigerant to a refrigerant pipe L2. The refrigerant discharged to the refrigerant pipe L2 is guided to the heating unit 20 via a refrigerant pipe L3 and a refrigerant pipe L4.

The heating unit 20 is a device that heats air (heating target) blown by the cabin blower 86 with a high-temperature and high-pressure refrigerant discharged from the compressor 10. The air heated by the heating unit 20 is blown into a vehicle interior. The refrigerant that has been subjected to heat exchange with the air in the heating unit 20 is guided to the expansion valve 40 disposed at a refrigerant pipe L5.

The accumulator 30 is a device that separates at least a part of a liquid component in a refrigerant sucked by the compressor 10. The accumulator 30 guides the refrigerant in a gas phase or a gas-liquid two phase to the compressor 10 via the refrigerant pipe L1.

The expansion valve 40 is a mechanism that is disposed at the refrigerant pipe L5 and that expands a refrigerant flowing out from the heating unit 20. An opening degree of the expansion valve 40 is controlled by the control unit 90. The refrigerant expanded by the expansion valve 40 circulates through the refrigerant pipe L5.

The expansion valve 50 is a mechanism that is disposed at a refrigerant pipe L6 connected to the refrigerant pipe L3 and that expands a refrigerant discharged from the compressor 10. An opening degree of the expansion valve 50 is controlled by the control unit 90. The refrigerant expanded by the expansion valve 50 is guided from the refrigerant pipe L6 to the accumulator 30 via a refrigerant pipe L7. The refrigerant pipe L7 is a pipe that connects the cabin heat exchanger 85 and the accumulator 30.

The on-off valve 61 is a device that is disposed at a refrigerant pipe L8 and that switches between an open state where a refrigerant is circulated through the refrigerant pipe L8 and a closed state where the refrigerant is not circulated through the refrigerant pipe L8. The refrigerant pipe L8 is a pipe that connects the refrigerant pipe L5 and a refrigerant pipe L9. The refrigerant pipe L9 is a pipe that connects a refrigerant pipe L10 and the refrigerant pipe L7. The refrigerant pipe L10 is a pipe that connects the outside heat exchanger 80 and the cabin heat exchanger 85.

The on-off valve 62 is a device that is disposed at the refrigerant pipe L6 and that switches between an open state where a refrigerant is circulated through the refrigerant pipe L6 and a closed state where the refrigerant is not circulated through the refrigerant pipe L6.

The on-off valve 63 is a device that is disposed at a refrigerant pipe L11 and that switches between an open state where a refrigerant is circulated through the refrigerant pipe L11 and a closed state where the refrigerant is not circulated through the refrigerant pipe L11.

The on-off valve 64 is a device that is disposed at the refrigerant pipe L5 and that switches between an open state where a refrigerant is circulated on an outside heat exchanger 80 side of a connection portion of the refrigerant pipe L5 with the refrigerant pipe L8 and a closed state where the refrigerant is not circulated on the outside heat exchanger 80 side of the connection portion of the refrigerant pipe L5 with the refrigerant pipe L8.

The on-off valve 65 is a device that is disposed at the refrigerant pipe L9 and that switches between an open state where a refrigerant is circulated through the refrigerant pipe L9 and a closed state where the refrigerant is not circulated through the refrigerant pipe L9.

The expansion valve 70 is a mechanism that is disposed at the refrigerant pipe L10 and that expands a refrigerant guided from the outside heat exchanger 80. An opening degree of the expansion valve 70 is controlled by the control unit 90. The refrigerant expanded by the expansion valve 70 is guided from the refrigerant pipe L10 to the cabin heat exchanger 85.

The outside heat exchanger 80 is a device that is installed outside the vehicle and that performs heat exchange between outside air and a refrigerant. The outside heat exchanger 80 operates as an evaporator during the heat pump heating operation and evaporates the refrigerant to cool the outside air. In addition, the outside heat exchanger 80 operates as a condenser during the cooling operation and condenses the refrigerant to heat the outside air. The outside fan 81 is a device that blows outside air to the outside heat exchanger 80 to promote heat exchange between the outside air and the refrigerant.

The cabin heat exchanger (evaporator) 85 is a device that cools or dehumidifies air by evaporating a refrigerant which has passed through the outside heat exchanger 80 and which is expanded by the expansion valve 70. The cabin blower 86 blows air toward the cabin heat exchanger 85 to guide the air cooled or dehumidified by the cabin heat exchanger 85 into the vehicle interior via the heating unit 20.

The control unit 90 is a device that controls each unit of the vehicle air conditioning device 100. The control unit 90 reads out and executes a control program stored in a storage unit (not shown) to execute various types of processing of controlling each unit of the vehicle air conditioning device 100.

The refrigerant heating heater 91 is a device that is disposed on a downstream side of the on-off valve 61 of the refrigerant pipe L8 and that heats a refrigerant which flows into the accumulator 30. For example, the control unit 90 operates the refrigerant heating heater 91 to heat the refrigerant in order to increase the pressure of the refrigerant sucked by the compressor 10 at the start of the hot gas heating operation.

The pressure sensor 92 is a sensor that detects the pressure of a refrigerant circulating through the refrigerant pipe L1. The temperature sensor 93 is a sensor that detects the temperature of the refrigerant circulating through the refrigerant pipe L1. The temperature sensor 94 is a sensor that detects the temperature of a refrigerant circulating through the refrigerant pipe L2. The temperature sensor 95 is a sensor that detects the temperature of a refrigerant circulating through the refrigerant pipe L5 between the heating unit 20 and the expansion valve 40. The pressure sensor 96 is a sensor that detects the pressure of the refrigerant circulating through the refrigerant pipe L5 between the heating unit 20 and the expansion valve 40.

In the present embodiment, although both the pressure sensor 92 and the temperature sensor 93 are provided at the refrigerant pipe L1, other aspects may be adopted. For example, only the temperature sensor 93 may be provided at the refrigerant pipe L1, and the pressure of a refrigerant that circulates through the refrigerant pipe L1 may be detected (estimated) from the temperature detected by the temperature sensor 93.

Heat Pump Heating Operation

An operation during the heat pump heating operation of the vehicle air conditioning device 100 according to the present embodiment will be described with reference to FIG. 2. FIG. 2 is a refrigerant circuit diagram showing a refrigerant flow during the heat pump heating operation of the vehicle air conditioning device 100. The heat pump heating operation is executed, for example, in a case where a temperature outside the vehicle at which the outside heat exchanger 80) is installed is not equal to or less than the predetermined temperature (for example, −20° C.).

Arrows shown in FIG. 2 indicate a refrigerant circulation direction. As shown in FIG. 2, during the heat pump heating operation, a refrigerant circulates in the order of the compressor 10, the heating unit 20, the expansion valve 40, the outside heat exchanger 80, the accumulator 30, and the compressor 10. The refrigerant pipes L1, L2, L3, L4, L5, L9, and L7 form a circulation flow path for circulating the refrigerant.

The outside heat exchanger 80 operates as an evaporator during the heat pump heating operation and evaporates a refrigerant to cool outside air. During the heat pump heating operation, the control unit 90 sets the on-off valves 64 and 65 to an open state and sets the on-off valves 61, 62, and 63 to a closed state.

Hot Gas Heating Operation

An operation during the hot gas heating operation of the vehicle air conditioning device 100 according to the present embodiment will be described with reference to FIG. 3. FIG. 3 is a refrigerant circuit diagram showing a refrigerant flow during the hot gas heating operation of the vehicle air conditioning device 100. Arrows shown in FIG. 3 indicate the refrigerant circulation direction. The hot gas heating operation is executed, for example, in a case where a temperature outside the vehicle at which the outside heat exchanger 80 is installed is equal to or less than the predetermined temperature (for example, −20° C.).

As shown in FIG. 3, during the hot gas heating operation, a part of a refrigerant circulates in the order of the compressor 10, the heating unit 20, the expansion valve 40, the accumulator 30, and the compressor 10. The refrigerant pipes L1, L2, L3, L4, L5, L8. L9, and L7 form a circulation flow path for circulating the refrigerant. The refrigerant pipes L5, L8, L9, and L7 guide the refrigerant, which has passed through the heating unit 20, to the accumulator 30.

In addition, the other part of the refrigerant is guided from the refrigerant pipe L3 to the refrigerant pipe L7 via the refrigerant pipe L6 without being circulated through the refrigerant pipes L4, L5, L8, and L9. The refrigerant pipe L6 is a bypass flow path that guides the refrigerant discharged from the compressor 10 to the accumulator 30 without passing through the heating unit 20.

In a case of performing the hot gas heating operation, the control unit 90 sets the on-off valve 64 and the on-off valve 65 to a closed state and circulates a refrigerant in the circulation flow path formed of the refrigerant pipes L1, L2, L3, L4, L5, L8, L9, and L7. Then, in the vehicle air conditioning device 100 of the present embodiment, the amount of the refrigerant to be enclosed in the refrigerant pipe formed of the refrigerant pipes L1 to L11 is set such that air can be heated by the heating unit 20 in a case where the on-off valve 64 and the on-off valve 65 are set to a closed state.

Herein, an operation during the hot gas heating operation of the vehicle air conditioning device 100 will be described with reference to FIGS. 4 to 6. FIGS. 4 and 5 are flowcharts showing the operation during the hot gas heating operation of the vehicle air conditioning device 100. Each step shown in FIGS. 4 and 5 is executed by the control unit 90. FIG. 6 is a Mollier diagram showing a state of a refrigerant during the hot gas heating operation.

In step S101, the control unit 90 controls the on-off valves 61, 63, 64, and 65 such that the on-off valves 61, 63, 64, and 65 are set to a closed state.

In step S102, the control unit 90 determines whether or not a pressure LP of a refrigerant detected by the pressure sensor 92 exceeds a threshold pressure, takes processing to step S108 in a case of YES, and takes processing to step S103 in a case of NO.

In step S103, the control unit 90 controls the on-off valve 62 such that the on-off valve 62 is set to an open state. The control unit 90 circulates the entire amount of the refrigerant discharged from the compressor 10 such that the refrigerant is guided to the accumulator 30 via the refrigerant pipe L6 by operating the compressor 10 with the on-off valve 62 set in an open state. In this manner, the control unit 90 sets the vehicle air conditioning device 100 to a first operation mode in which the refrigerant discharged from the compressor 10 is guided to the refrigerant pipe L6 without being guided to the heating unit 20.

In step S104, the control unit 90 performs control such that the opening degree of the expansion valve 50 is adjusted. Step S104 is executed in a case where NO is determined in step S102 and in a state where the pressure LP of the refrigerant detected by the pressure sensor 92 is equal to or lower than the threshold pressure and the hot gas heating operation using the heating unit 20 cannot be performed.

Therefore, in step S104, the opening degree of the expansion valve 50 is adjusted to adjust a flow rate of the refrigerant guided to the accumulator 30 via the refrigerant pipe L6, in order to cause a state where the hot gas heating operation using the heating unit 20 can be executed. The control unit 90 controls the opening degree of the expansion valve 50 such that the opening degree of the expansion valve 50 increases as a difference between the pressure LP of the refrigerant detected by the pressure sensor 92 and the threshold pressure increases. By doing so, a start time required to cause a state where the hot gas heating operation using the heating unit 20 can be executed can be shortened.

In step S105, the control unit 90 determines whether or not the pressure LP of the refrigerant detected by the pressure sensor 92 exceeds the threshold pressure, takes proceeding to step S106 in a case of YES, and adjusts the opening degree of the expansion valve 50 in step S104 again in a case of NO.

In step S106, the control unit 90 adjusts the opening degree of the expansion valve 40 before the on-off valve 61 is set to an open state in step S107. The opening degree of the expansion valve 40 is adjusted to suppress a decrease in the pressure of the refrigerant that circulates in a refrigerating cycle when the on-off valve 61 is set to an open state.

In step S107, the control unit 90 controls the on-off valve 61 such that the on-off valve 61 is set to an open state. By setting the on-off valve 61 to an open state, a part of the refrigerant discharged from the compressor 10 circulates in the order of the compressor 10, the heating unit 20, the expansion valve 40, the accumulator 30, and the compressor 10.

As described above, the control unit 90 switches the vehicle air conditioning device 100 from the first operation mode in which the refrigerant discharged from the compressor 10 is guided to the refrigerant pipe L6 without being guided to the heating unit 20 to a second operation mode in which the refrigerant discharged from the compressor 10 is guided to both the heating unit 20 and the refrigerant pipe L6. The on-off valve 61 functions as a switching unit that switches between the first operation mode and the second operation mode. The control unit 90 controls the on-off valve 61 to switch from the first operation mode to the second operation mode in accordance with the pressure of the refrigerant sucked by the compressor 10 exceeding the threshold pressure.

In step S108, the control unit 90 controls the on-off valve 62 such that the on-off valve 62 is set to an open state. In step S109, the control unit 90 controls the on-off valve 61 such that the on-off valve 61 is set to an open state. The control unit 90 sets the on-off valve 62 and the on-off valve 61 to an open state and operates the compressor 10, resulting in a state where a part of the refrigerant discharged from the compressor 10 is guided to the heating unit 20 and the other part of the refrigerant discharged from the compressor 10 is guided to the accumulator 30 from the refrigerant pipe L6 without passing through the heating unit 20.

In step S110, the control unit 90 adjusts the opening degree of the expansion valve 40 such that the refrigerant which has passed through the heating unit 20 becomes a liquid refrigerant in performing the hot gas heating operation of guiding the refrigerant to the heating unit 20. The control unit 90 adjusts the opening degree of the expansion valve 40 such that a supercooling degree SC, which is a difference between the temperature of the refrigerant at point b and the temperature of the refrigerant at point b′ shown in FIG. 6, is a predetermined value. The control unit 90 calculates the supercooling degree SC from a temperature detected by the temperature sensor 95 and a pressure detected by the pressure sensor 96.

In step S111, the control unit 90 calculates specific enthalpies ha, hb, and hc of points a, b, and c shown in FIG. 6, respectively. The specific enthalpy ha of point a is calculated from a temperature detected by the temperature sensor 94 and the pressure detected by the pressure sensor 96. The specific enthalpy hb of point b is calculated from the temperature detected by the temperature sensor 95 and the pressure detected by the pressure sensor 96. The specific enthalpy he of point c is calculated from any one of a temperature detected by the temperature sensor 93 or a pressure detected by the pressure sensor 92 and a rotation speed of the motor that drives the compressor 10.

In step S112, the control unit 90 calculates a refrigerant flow rate Gr1 of the refrigerant pipe L6. The refrigerant flow rate Gr1 is calculated from the opening degree of the expansion valve 50, a pressure HP of point a, the pressure LP of point c, and the temperature detected by the temperature sensor 93.

In step S113, the control unit 90 calculates a refrigerant flow rate Gr2 of the refrigerant pipe L5. The refrigerant flow rate Gr2 is calculated from the opening degree of the expansion valve 40, the pressure HP of point b, the pressure LP of point c, and the temperature detected by the temperature sensor 93.

In step S114, the control unit 90 determines whether or not the pressure LP of the refrigerant detected by the pressure sensor 92 exceeds a predetermined pressure, takes processing to step S115 in a case of YES, and takes processing to step S116 in a case of NO. The predetermined pressure is determined in advance as a pressure that is higher than the threshold pressure described above and that is suitable for the hot gas heating operation.

In step S115, the control unit 90 increases the opening degree of the expansion valve 50 such that (ha−hc)×Gr1>(hc−hb)>Gr2 is satisfied. By doing so, the proportion of a gas refrigerant in an inflow refrigerant that flows into the accumulator 30, including the refrigerant expanded by the expansion valve 40 and the refrigerant expanded by the expansion valve 50, can be made larger than the proportion of a gas refrigerant in an outflow refrigerant that flows out from the accumulator 30.

In FIG. 6, by increasing the opening degree of the expansion valve 50, point c corresponding to an outlet side (a suction side of the compressor 10) of the accumulator 30 can be closer to point e than point d. Point d corresponds to the downstream side of the expansion valve 40, and point e corresponds to the downstream side of the expansion valve 50.

By setting the proportion of the gas refrigerant in the inflow refrigerant that flows into the accumulator 30 to be larger than the proportion of the gas refrigerant in the outflow refrigerant that flows out from the accumulator 30, the amount of the liquid refrigerant stored in the accumulator 30 is reduced. Accordingly, the pressure of the refrigerant that flows into the compressor 10 increases with an increase in the refrigerant circulating through the refrigerating cycle, and a decrease in the power of the compressor 10 can be suppressed.

In step S116, the control unit 90 reduces the opening degree of the expansion valve 50 such that (ha−hc)×Gr1<(hc−hb)×Gr2 is satisfied. By doing so, the proportion of the liquid refrigerant in the inflow refrigerant that flows into the accumulator 30, including the refrigerant expanded by the expansion valve 40 and the refrigerant expanded by the expansion valve 50, can be made larger than the proportion of the liquid refrigerant in the outflow refrigerant that flows out from the accumulator 30. In FIG. 6, by reducing the opening degree of the expansion valve 50, point c corresponding to the outlet side (the suction side of the compressor 10) of the accumulator 30 can be closer to point d than point e.

By setting the proportion of the liquid refrigerant in the inflow refrigerant that flows into the accumulator 30 to be larger than the proportion of the liquid refrigerant in the outflow refrigerant that flows out from the accumulator 30, the amount of the liquid refrigerant stored in the accumulator 30 is increased, and the proportion of the liquid refrigerant included in the refrigerant that flows out from the accumulator 30 is reduced. Accordingly, the pressure of the refrigerant that flows into the compressor 10 is reduced with a reduction in the amount of the refrigerant circulating through the refrigerating cycle, and an increase in the torque of the compressor 10 can be suppressed.

In step S117, the control unit 90 determines whether or not an instruction to finish the hot gas heating operation is input and finishes processing of the present flowchart in a case of YES. In a case of NO, processing after step S110 is executed again.

In the hot gas heating operation described hereinbefore, in a case of reducing the power of the compressor 10, the control unit 90 controls the opening degree (first opening degree) of the expansion valve 40 and the opening degree (second opening degree) of the expansion valve 50 such that the proportion of the liquid refrigerant in the inflow refrigerant that flows into the accumulator 30 is not changed. In addition, in a case of increasing the power of the compressor 10, the control unit 90 controls the opening degree (first opening degree) of the expansion valve 40 and the opening degree (second opening degree) of the expansion valve 50 such that the proportion of the liquid refrigerant in the inflow refrigerant that flows into the accumulator 30 is not changed.

Dehumidification and Heating Operation

An operation during a dehumidification and heating operation of the vehicle air conditioning device 100 according to the present embodiment will be described with reference to FIG. 7. FIG. 7 is a refrigerant circuit diagram showing a refrigerant flow during the dehumidification and heating operation of the vehicle air conditioning device 100.

Arrows shown in FIG. 7 indicate the refrigerant circulation direction. As shown in FIG. 7, during the dehumidification and heating operation, a refrigerant circulates in the order of the compressor 10, the heating unit 20, the expansion valve 40, the outside heat exchanger 80, the cabin heat exchanger 85, the accumulator 30, and the compressor 10. The refrigerant pipes L1, L2, L3, L4, L5, L10, and L7 form a circulation flow path for circulating the refrigerant.

During the dehumidification and heating operation, the outside heat exchanger 80 operates as an evaporator and evaporates a refrigerant to cool outside air. During the dehumidification and heating operation, the control unit 90 sets the on-off valve 64 to an open state and sets the on-off valves 61, 62, 63, and 65 to a closed state. The control unit 90 can heat air in the heating unit 20 to blow air while dehumidifying the air of moisture contained therein by driving the cabin blower 86 to guide the air dehumidified by the cabin heat exchanger 85 to the heating unit 20.

Cooling Operation

An operation during the cooling operation of the vehicle air conditioning device 100 according to the present embodiment will be described with reference to FIG. 8. FIG. 8 is a refrigerant circuit diagram showing a refrigerant flow during the cooling operation of the vehicle air conditioning device 100.

Arrows shown in FIG. 8 indicate the refrigerant circulation direction. As shown in FIG. 8, during the cooling operation, a refrigerant circulates in the order of the compressor 10, the outside heat exchanger 80, the cabin heat exchanger 85, the accumulator 30, and the compressor 10. The refrigerant pipes L1, L2, L11, L5, L10, and L7 form a circulation flow path for circulating the refrigerant.

During the cooling operation, the outside heat exchanger 80 operates as a condenser and condenses a refrigerant to heat outside air. During the cooling operation, the control unit 90 sets the on-off valves 63 and 64 to an open state and sets the on-off valves 61, 62, and 65 to a closed state. The control unit 90 can drive the cabin blower 86 to blow air cooled by the outside heat exchanger 80 into the vehicle interior.

The workings and effects of the vehicle air conditioning device 100 of the present embodiment described hereinbefore will be described.

With the vehicle air conditioning device 100 of the present embodiment, a part of a high-temperature and high-pressure refrigerant discharged from the compressor 10 is supplied to the heating unit 20, and the heating unit 20 heats air (heating target). The refrigerant that has passed through the heating unit 20 is expanded by the expansion valve 40 and is guided to the accumulator 30 through the refrigerant pipes L5, L8, L9, and L7. In addition, the other part of the high-temperature and high-pressure refrigerant discharged from the compressor 10 is guided to the refrigerant pipe L6 (bypass flow path) and is expanded by the expansion valve 50. The refrigerant expanded by the expansion valve 50 merges with a refrigerant circulating through the refrigerant pipe L7 and is guided to the accumulator 30.

With the vehicle air conditioning device 100 according to the present embodiment, in a case where the pressure of a refrigerant sucked by the compressor 10 is lower than the predetermined pressure, the opening degree of the expansion valve 40 and the opening degree of the expansion valve 50 are controlled such that the proportion of a gas refrigerant in an inflow refrigerant flowing into the accumulator 30 is larger than the proportion of a gas refrigerant in an outflow refrigerant flowing out from the accumulator 30. For this reason, the amount of a liquid refrigerant stored in the accumulator 30 is reduced. Accordingly, the pressure of a refrigerant flowing into the compressor 10 increases with an increase in a refrigerant circulating through the circulation flow path (refrigerant pipes L5, L8, L9, and L7) and the bypass flow path (refrigerant pipe L6), and a decrease in the power of the compressor 10 can be suppressed.

In addition, with the vehicle air conditioning device 100 according to the present embodiment, in a case where the pressure of a refrigerant sucked by the compressor 10 is higher than the predetermined pressure, the opening degree of the expansion valve 40 and the opening degree of the expansion valve 50 are controlled such that the proportion of a liquid refrigerant in an inflow refrigerant flowing into the accumulator 30 is larger than the proportion of a liquid refrigerant in an outflow refrigerant flowing out from the accumulator 30. For this reason, the amount of the liquid refrigerant stored in the accumulator 30 increases. Accordingly, the pressure of a refrigerant flowing into the compressor 10 is reduced with a reduction in a refrigerant circulating through the circulation flow path (refrigerant pipes L5, L8, L9, and L7) and the bypass flow path (refrigerant pipe L6), and an increase in the torque of the compressor 10 can be suppressed.

With the vehicle air conditioning device 100 of the present embodiment, during the hot gas heating operation of heating air using the power of the compressor 10, the first operation mode can be set in which a refrigerant discharged from the compressor 10 is guided to the bypass flow path without being guided to the circulation flow path until the pressure of a refrigerant sucked by the compressor 10 reaches the threshold pressure, and the pressure of the refrigerant can be made to quickly reach the threshold pressure. In addition, the second operation mode can be set in accordance with whether or not the pressure of the refrigerant sucked by the compressor 10 exceeds the threshold pressure, and the air can be appropriately heated by the heating unit 20.

With the vehicle air conditioning device 100 of the present embodiment, in a case where the power of the compressor 10 is reduced or increased, fluctuations of the pressure of a refrigerant sucked by the compressor in accordance with the reduction in the power of the compressor can be appropriately suppressed.

With the vehicle air conditioning device 100 of the present embodiment, in a case where a refrigerant is circulated in the circulation flow path by setting the on-off valve 64 and the on-off valve 65 to a closed state, a part of the refrigerant enclosed in a refrigerant flow path remains in other refrigerant flow paths different from the circulation flow path, including the downstream side of the on-off valve 64 of the refrigerant pipe L5 and the refrigerant pipe L9. In addition, even when the on-off valve 64 and the on-off valve 65 are set to a closed state, a part of the refrigerant circulating through the circulation flow path flows into the downstream side of the on-off valve 64 of the refrigerant pipe L5 and the refrigerant pipe L9, and thus the amount of the refrigerant circulating through the circulation flow path is reduced.

With the vehicle air conditioning device 100 of the present embodiment, in a case where a refrigerant is circulated through the circulation flow path by setting the on-off valve 64 and the on-off valve 65 to a closed state, the amount of the refrigerant to be enclosed in the refrigerant flow path, including the circulation flow path, the bypass flow path, a first flow path (the downstream side of the on-off valve 64 of the refrigerant pipe L5), and a second flow path (refrigerant pipe L9), is set such that air can be heated by the heating unit 20. For this reason, in a case where the refrigerant is circulated through the circulation flow path by setting the on-off valve 64 and the on-off valve 65 to a closed state, the air can be appropriately heated by the heating unit 20.

With the vehicle air conditioning device 100 of the present embodiment, a refrigerant that flows into the accumulator 30 is heated by the refrigerant heating heater 91, and thus the specific enthalpy of the refrigerant that flows into the accumulator 30 can be increased.

With the vehicle air conditioning device 100 of the present embodiment, air can be heated and blown by the heating unit 20 while dehumidifying the air of moisture contained therein by driving the cabin blower 86 to guide the air dehumidified by the cabin heat exchanger 85 to the heating unit 20.

With the vehicle air conditioning device 100 of the present embodiment, since the opening degree of the expansion valve 40 is adjusted such that a refrigerant which has passed through the heating unit 20 becomes a liquid refrigerant, flowing of a gas-liquid two phase refrigerant into the expansion valve 40 and an increase in a refrigerant flowing sound can be appropriately prevented.

The air conditioning device and the method for controlling an air conditioning device, which are described in each embodiment described hereinbefore, are understood, for example, as follows.

According to a first aspect of the present disclosure, there is provided an air conditioning device (100) including a compressor (10) that compresses a refrigerant, a heating unit (20) that heats a heating target with the refrigerant discharged from the compressor, an accumulator (30) that separates a liquid component in the refrigerant sucked by the compressor, a circulation flow path (L5, L8, L9, L7) that guides the refrigerant, which has passed through the heating unit, to the accumulator, a bypass flow path (L6) that guides the refrigerant discharged from the compressor to the accumulator without passing the refrigerant through the heating unit, a first expansion mechanism (40) that is disposed at the circulation flow path and that expands the refrigerant flowing out from the heating unit, a second expansion mechanism (50) that is disposed at the bypass flow path and that expands the refrigerant discharged from the compressor, and a control unit (90) that controls a first opening degree of the first expansion mechanism and a second opening degree of the second expansion mechanism, in which the control unit in a case where a pressure of the refrigerant sucked by the compressor is lower than a predetermined pressure, controls the first opening degree and the second opening degree such that a proportion of a gas refrigerant in an inflow refrigerant flowing into the accumulator, including the refrigerant expanded by the first expansion mechanism and the refrigerant expanded by the second expansion mechanism, is larger than a proportion of a gas refrigerant in an outflow refrigerant flowing out from the accumulator, and in a case where the pressure of the refrigerant sucked by the compressor is higher than the predetermined pressure, controls the first opening degree and the second opening degree such that a proportion of a liquid refrigerant in the inflow refrigerant is larger than a proportion of a liquid refrigerant in the outflow refrigerant flowing out from the accumulator.

With the air conditioning device according to the first aspect of the present disclosure, a part of the high-temperature and high-pressure refrigerant discharged from the compressor is supplied to the heating unit, and the heating unit heats the heating target. The refrigerant that has passed through the heating unit is expanded by the first expansion mechanism and is guided to the accumulator through the circulation flow path. In addition, the other part of the high-temperature and high-pressure refrigerant discharged from the compressor is guided to the bypass flow path and is expanded by the second expansion mechanism. The refrigerant expanded by the second expansion mechanism merges with a refrigerant that circulates through the circulation flow path and is guided to the accumulator.

With the air conditioning device according to the first aspect of the present disclosure, in a case where the pressure of the refrigerant sucked by the compressor is lower than the predetermined pressure, the first opening degree and the second opening degree are controlled such that the proportion of the gas refrigerant in the inflow refrigerant flowing into the accumulator is larger than the proportion of the gas refrigerant in the outflow refrigerant flowing out from the accumulator. For this reason, the amount of the liquid refrigerant stored in the accumulator is reduced. Accordingly, the pressure of the refrigerant that flows into the compressor increases with an increase in the refrigerant circulating through the circulation flow path and the bypass flow path, and a decrease in the power of the compressor can be suppressed.

With the air conditioning device according to the first aspect of the present disclosure, in a case where the pressure of the refrigerant sucked by the compressor is higher than the predetermined pressure, the first opening degree and the second opening degree are controlled such that the proportion of the liquid refrigerant in the inflow refrigerant flowing into the accumulator is larger than the proportion of the liquid refrigerant in the outflow refrigerant flowing out from the accumulator. For this reason, the amount of the liquid refrigerant stored in the accumulator increases. Accordingly, the pressure of the refrigerant that flows into the compressor is reduced with a reduction in the amount of the refrigerant circulating through the circulation flow path and the bypass flow path, and an increase in the torque of the compressor can be suppressed.

In the first aspect, the air conditioning device according to a second aspect of the present disclosure further includes the following configuration. That is, a switching unit (61) that switches between a first operation mode in which the refrigerant discharged from the compressor is guided to the bypass flow path without being guided to the circulation flow path and a second operation mode in which the refrigerant discharged from the compressor is guided to both the circulation flow path and the bypass flow path is included, and the control unit controls the switching unit such that the first operation mode is switched to the second operation mode in accordance with whether or not the pressure of the refrigerant sucked by the compressor exceeds a threshold pressure.

With the air conditioning device according to the second aspect of the present disclosure, during the hot gas heating operation of heating a heating target using the power of the compressor, the first operation mode can be set in which the refrigerant discharged from the compressor is guided to the bypass flow path without being guided to the circulation flow path until the pressure of the refrigerant sucked by the compressor reaches the threshold pressure, and the pressure of the refrigerant can be made to quickly reach the threshold pressure. In addition, the second operation mode can be set in accordance with whether or not the pressure of the refrigerant sucked by the compressor exceeds the threshold pressure, and the heating target can be appropriately heated by the heating unit.

In the first aspect or the second aspect, the air conditioning device according to a third aspect of the present disclosure further includes the following configuration. That is, in a case of reducing power of the compressor, the control unit controls the first opening degree and the second opening degree such that the proportion of the liquid refrigerant in the inflow refrigerant is not changed.

With the air conditioning device according to the third aspect of the present disclosure, in a case of reducing the power of the compressor, fluctuations of the pressure of the refrigerant sucked by the compressor in accordance with a reduction in the power of the compressor can be appropriately suppressed.

In the first aspect or the second aspect, the air conditioning device according to a fourth aspect of the present disclosure further includes the following configuration.

That is, in a case of increasing power of the compressor, the control unit controls the first opening degree and the second opening degree such that the proportion of the liquid refrigerant in the inflow refrigerant is not changed.

With the air conditioning device according to the fourth aspect of the present disclosure, in a case where the power of the compressor is increased, fluctuations of the pressure of the refrigerant sucked by the compressor in accordance with an increase in the power of the compressor can be appropriately suppressed.

In the first aspect or the second aspect, the air conditioning device according to a fifth aspect of the present disclosure further includes the following configuration. That is, a heat exchanger (80) that exchanges heat between outside air and the refrigerant, a first flow path (L5) that guides the refrigerant, which has passed through the heating unit, to the heat exchanger, a second flow path (L9) that guides the refrigerant, which has passed through the heat exchanger, to the accumulator, a first on-off valve (64) that is disposed at the first flow path, and a second on-off valve (65) that is disposed at the second flow path are included, and in a case of circulating the refrigerant in the circulation flow path by setting the first on-off valve and the second on-off valve to a closed state, an amount of the refrigerant to be enclosed in a refrigerant flow path, including the circulation flow path, the bypass flow path, the first flow path, and the second flow path, is set such that the heating unit is capable of heating the heating target.

With the air conditioning device according to the fifth aspect of the present disclosure, in a case of circulating the refrigerant in the circulation flow path by setting the first on-off valve and the second on-off valve to a closed state, a part of the refrigerant enclosed in the refrigerant flow path remains in other refrigerant flow paths different from the circulation flow path, including the first flow path and the second flow path. In addition, even when the first on-off valve and the second on-off valve are set to a closed state, a part of the refrigerant circulating through the circulation flow path flows into the first flow path and the second flow path, and thus the amount of the refrigerant circulating through the circulation flow path is reduced.

With the air conditioning device according to the fifth aspect of the present disclosure, in a case of circulating a refrigerant through the circulation flow path by setting the first on-off valve and the second on-off valve to a closed state, the amount of the refrigerant to be enclosed in the refrigerant flow path, including the circulation flow path, the bypass flow path, the first flow path, and the second flow path, is set such that the heating target can be heated by the heating unit. For this reason, in a case of circulating the refrigerant through the circulation flow path by setting the first on-off valve and the second on-off valve to a closed state, the heating target can be appropriately heated by the heating unit.

In the first aspect or the second aspect, the air conditioning device according to a sixth aspect of the present disclosure further includes the following configuration. That is, a refrigerant heating heater (95) that heats the refrigerant flowing into the accumulator is included.

With the air conditioning device according to the sixth aspect of the present disclosure, the refrigerant flowing into the accumulator is heated by the refrigerant heating heater, and thus the pressure of the refrigerant flowing into the accumulator can be increased.

In the first aspect or the second aspect, the air conditioning device according to a seventh aspect of the present disclosure further includes the following configuration. That is, a heat exchanger (80) that exchanges heat between outside air and the refrigerant, an evaporator (85) that evaporates the refrigerant which has passed through the heat exchanger, a blower (86) that guides air dehumidified by the evaporator to the heating unit, a first flow path (L5) that guides the refrigerant, which has passed through the heating unit, to the heat exchanger, and a second flow path (L9) that guides the refrigerant, which has passed through the heat exchanger, to the accumulator via the evaporator are included.

With the air conditioning device according to the seventh aspect of the present disclosure, air can be heated and blown by the heating unit while dehumidifying the air of moisture contained therein by driving the blower to guide the air dehumidified by the evaporator to the heating unit.

In the first aspect or the second aspect, the air conditioning device according to an eighth aspect of the present disclosure further includes the following configuration. That is, the control unit controls an opening degree of the first expansion mechanism such that the refrigerant which has passed through the heating unit becomes the liquid refrigerant.

With the air conditioning device according to the eighth aspect of the present disclosure, since the opening degree of the first expansion mechanism is adjusted such that the refrigerant which has passed through the heating unit becomes the liquid refrigerant, flowing of a gas-liquid two phase refrigerant into the first expansion mechanism and an increase in a refrigerant flowing sound can be appropriately prevented.

According to a ninth aspect of the present disclosure, there is provided a method for controlling an air conditioning device, in which the air conditioning device includes a compressor that compresses a refrigerant, a heating unit that heats a heating target with the refrigerant discharged from the compressor, an accumulator that separates a liquid component in the refrigerant sucked by the compressor, a circulation flow path that guides the refrigerant, which has passed through the heating unit, to the accumulator, a bypass flow path that guides the refrigerant discharged from the compressor to the accumulator without passing the refrigerant through the heating unit, a first expansion mechanism that is disposed at the circulation flow path and that expands the refrigerant flowing out from the heating unit, and a second expansion mechanism that is disposed at the bypass flow path and that expands the refrigerant discharged from the compressor, the method including a first control step of, in a case where a pressure of the refrigerant sucked by the compressor is lower than a predetermined pressure, controlling a first opening degree of the first expansion mechanism and a second opening degree of the second expansion mechanism such that a proportion of a gas refrigerant in an inflow refrigerant flowing into the accumulator, including the refrigerant expanded by the first expansion mechanism and the refrigerant expanded by the second expansion mechanism, is larger than a proportion of a gas refrigerant in an outflow refrigerant flowing out from the accumulator, and a second control step of, in a case where the pressure of the refrigerant sucked by the compressor is higher than the predetermined pressure, controlling the first opening degree and the second opening degree such that a proportion of a liquid refrigerant in the inflow refrigerant is larger than a proportion of a liquid refrigerant in the outflow refrigerant flowing out from the accumulator.

With the method for controlling an air conditioning device according to the ninth aspect of the present disclosure, a part of the high-temperature and high-pressure refrigerant discharged from the compressor is supplied to the heating unit, and the heating unit heats the heating target. The refrigerant that has passed through the heating unit is expanded by the first expansion mechanism and is guided to the accumulator through the circulation flow path. In addition, the other part of the high-temperature and high-pressure refrigerant discharged from the compressor is guided to the bypass flow path and is expanded by the second expansion mechanism. The refrigerant expanded by the second expansion mechanism merges with a refrigerant that circulates through the circulation flow path and is guided to the accumulator.

With the method for controlling an air conditioning device according to the ninth aspect of the present disclosure, in a case where the pressure of the refrigerant sucked by the compressor is lower than the predetermined pressure, the first opening degree and the second opening degree are controlled such that the proportion of the gas refrigerant in the inflow refrigerant flowing into the accumulator is larger than the proportion of the gas refrigerant in the outflow refrigerant flowing out from the accumulator. For this reason, the amount of the liquid refrigerant stored in the accumulator is reduced, and the proportion of the liquid refrigerant included in the refrigerant that flows out from the accumulator increases. Accordingly, the pressure of the refrigerant that flows into the compressor increases with an increase in the refrigerant circulating through the circulation flow path and the bypass flow path, and a decrease in the power of the compressor can be suppressed.

In addition, with the method for controlling an air conditioning device according to the ninth aspect of the present disclosure, in a case where the pressure of the refrigerant sucked by the compressor is higher than the predetermined pressure, the first opening degree and the second opening degree are controlled such that the proportion of the liquid refrigerant in the inflow refrigerant flowing into the accumulator is larger than the proportion of the liquid refrigerant in the outflow refrigerant flowing out from the accumulator. For this reason, the amount of the liquid refrigerant stored in the accumulator increases, and the proportion of the liquid refrigerant included in the refrigerant that flows out from the accumulator is reduced. Accordingly, the pressure of the refrigerant that flows into the compressor is reduced with a reduction in the amount of the refrigerant circulating through the circulation flow path and the bypass flow path, and an increase in the torque of the compressor can be suppressed.

Reference Signs List

• • 10: compressor
  • 20: heating unit
  • 30: accumulator
  • 40: expansion valve (first expansion mechanism)
  • 50: expansion valve (second expansion mechanism)
  • 61, 62, 63: on-off valve
  • 64: on-off valve (first on-off valve)
  • 65: on-off valve (second on-off valve)
  • 70: expansion valve
  • 80: outside heat exchanger
  • 81: outside fan
  • 85: cabin heat exchanger (evaporator)
  • 86: cabin blower
  • 90: control unit
  • 91: refrigerant heating heater
  • 92, 96: pressure sensor
  • 93, 94, 95: temperature sensor
  • 100: vehicle air conditioning device
  • Gr1, Gr2: refrigerant flow rate
  • L1, L2, L3, L4, L5, L6, L7, L8, L9, L10, L11: refrigerant pipe