METHOD OF OPERATING A MAKEUP AIR MODULE OF AN AIR CONDITIONER UNIT

Description

FIELD OF THE INVENTION

The present disclosure relates generally to air conditioner units, in particular air conditioner units having a fresh air make-up capability.

BACKGROUND OF THE INVENTION

Air conditioners or air conditioner units are conventionally utilized to adjust the temperature in an indoor space. A typical type of air conditioner unit, commonly referred to as packaged terminal air conditioners (PTAC), may be utilized to adjust the temperature in, for example, a single room or group of rooms, or conditioned spaces, of a structure such as a dwelling or an office building. Such air conditioning units commonly include a reversible heat pump system with a closed refrigeration loop to heat or cool the indoor air. In some applications, the air conditioning unit introduces outdoor makeup air to provide fresh air ventilation to the conditioned space. Typically, the makeup air is introduced to a recirculating flow of indoor conditioned air prior to introduction of the combined flow to the conditioned space. The makeup air may be conditioned before it is introduced to the recirculating flow of indoor air, the combined flow of indoor air and outdoor makeup air may be conditioned before it is introduced to the conditioned space, or unconditioned outdoor makeup air may be introduced to a flow of conditioned indoor air before the combined flow is introduced to the conditioned space.

Under some circumstances, the cooling or heating capacity of the air conditioning unit is insufficient to condition the flow of outdoor makeup air to the desired indoor air characteristics, e.g., temperature. For example, outdoor air temperature may be too high, or too low, for the air conditioning unit to cool, or heat, to the desired temperature of the conditioned space. In another example, the air conditioning unit may be unable to properly condition the makeup air due to equipment malfunction or defect. In either case, continued introduction of outdoor makeup air to the conditioned space will negatively impact the temperature of the conditioned space. Accordingly, an air conditioning unit controlled to adjust or block the flow of makeup air when the conditioning capacity of the air conditioner is exceeded may be desirable.

BRIEF DESCRIPTION OF THE INVENTION

Aspects and advantages of the invention will be set forth in part in the following description, may be apparent from the description, or may be learned through practice of the invention.

In one exemplary aspect, an air conditioning system is provided including a refrigeration loop comprising an indoor heat exchanger and an outdoor heat exchanger, a compressor operably coupled to the refrigeration loop and being configured to urge refrigerant through the refrigeration loop, an indoor fan operable to urge an inlet flow of indoor air through the indoor heat exchanger, an auxiliary fan operable to urge an outdoor makeup air flow to combine with the inlet flow to produce a mixed discharge air flow, and a controller operably coupled to the compressor, the indoor fan, and the auxiliary fan. The controller is configured to operate the compressor at a first compressor speed, operate the indoor fan at a first indoor fan speed, operate the auxiliary fan at a first auxiliary fan speed, determine a temperature of the inlet flow of indoor air, determine a temperature of the mixed discharge air flow, determine that a temperature differential between the inlet flow temperature and the mixed discharge flow temperature deviates from a predetermined range, and implement a responsive action in response to determining the temperature differential deviates from the predetermined range.

In another exemplary aspect, a method of operating an air conditioning system is provided. The air conditioning system includes a refrigeration loop comprising an indoor heat exchanger, an outdoor heat exchanger, a compressor configured to urge refrigerant through the refrigeration loop, an indoor fan operable to urge an inlet flow of indoor air through the indoor heat exchanger, and an auxiliary fan operable to urge an outdoor makeup air flow to combine with the inlet flow to produce a mixed discharge air flow. The method includes operating the compressor at a first compressor speed, operating the indoor fan at a first indoor fan speed, operating the auxiliary fan at a first auxiliary fan speed, determining a temperature of the inlet flow of indoor air, determining a temperature of the mixed discharge air flow, determining that a temperature differential between the inlet flow temperature and the mixed discharge flow temperature deviates from a predetermined range, and implementing a responsive action in response to determining the temperature differential deviates from the predetermined range.

These and other features, aspects and advantages of the present invention will become better understood with reference to the following description and appended claims. The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and, together with the description, serve to explain the principles of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

A full and enabling disclosure of the present invention, including the best mode thereof, directed to one of ordinary skill in the art, is set forth in the specification, which makes reference to the appended figures.

FIG. 1 provides a perspective view of an air conditioner unit in partial exploded view in accordance with an exemplary embodiment of the present disclosure;

FIG. 2 is another front perspective view of the indoor portion of the exemplary air conditioner unit of FIG. 1;

FIG. 3 is a schematic representation of a refrigeration loop in accordance with an embodiment of the present disclosure;

FIG. 4 is a rear perspective view of an outdoor portion of the exemplary air conditioner unit of FIG. 1 in accordance with an embodiment of the present disclosure;

FIG. 5 is an enlarged front perspective view of a portion of the air conditioner unit of FIG. 4 in accordance with an embodiment of the present disclosure;

FIG. 6 is a rear perspective view of the exemplary air conditioner unit and bulkhead of FIG. 4 including a fan assembly for providing make-up air in accordance with an embodiment of the present disclosure;

FIG. 7 is a side cross sectional view of the exemplary air conditioner unit of FIG. 1;

FIG. 8 illustrates a method of operating an air conditioner unit in accordance with an embodiment of the present disclosure;

FIG. 9 illustrates a flow chart for a method of operation of an exemplary air conditioner unit in a cooling mode in accordance with an embodiment of the present disclosure; and

FIG. 10 illustrates a flow chart for a method of operation of an exemplary air conditioner unit in a heating mode in accordance with an embodiment of the present disclosure.

Repeat use of reference characters in the present specification and drawings is intended to represent the same or analogous features or elements of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

Reference now will be made in detail to embodiments of the invention, one or more examples of which are illustrated in the drawings. Each example is provided by way of explanation of the invention, not limitation of the invention. In fact, it will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the scope or spirit of the invention. For instance, features illustrated or described as part of one embodiment can be used with another embodiment to yield a still further embodiment. Thus, it is intended that the present invention covers such modifications and variations as come within the scope of the appended claims and their equivalents.

As used herein, the terms “first,” “second,” and “third” may be used interchangeably to distinguish one component from another and are not intended to signify location or importance of the individual components. The terms “includes” and “including” are intended to be inclusive in a manner similar to the term “comprising.” Similarly, the term “or” is generally intended to be inclusive (i.e., “A or B” is intended to mean “A or B or both”). In addition, here and throughout the specification and claims, range limitations may be combined and/or interchanged. Such ranges are identified and include all the sub-ranges contained therein unless context or language indicates otherwise. For example, all ranges disclosed herein are inclusive of the endpoints, and the endpoints are independently combinable with each other. The singular forms “a,” “an,” and “the” include plural references unless the context clearly dictates otherwise.

Approximating language, as used herein throughout the specification and claims, may be applied to modify any quantitative representation that could permissibly vary without resulting in a change in the basic function to which it is related. Accordingly, a value modified by a term or terms, such as “generally,” “about,” “approximately,” and “substantially,” are not to be limited to the precise value specified. In at least some instances, the approximating language may correspond to the precision of an instrument for measuring the value, or the precision of the methods or machines for constructing or manufacturing the components and/or systems. For example, the approximating language may refer to being within a 10 percent margin, i.e., including values within ten percent greater or less than the stated value. In this regard, for example, when used in the context of an angle or direction, such terms include within ten degrees greater or less than the stated angle or direction, e.g., “generally vertical” includes forming an angle of up to ten degrees in any direction, e.g., clockwise or counterclockwise, with the vertical direction V.

The word “exemplary” is used herein to mean “serving as an example, instance, or illustration.” In addition, references to “an embodiment” or “one embodiment” does not necessarily refer to the same embodiment, although it may. Any implementation described herein as “exemplary” or “an embodiment” is not necessarily to be construed as preferred or advantageous over other implementations. Moreover, each example is provided by way of explanation of the invention, not limitation of the invention. In fact, it will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the scope of the invention. For instance, features illustrated or described as part of one embodiment can be used with another embodiment to yield a still further embodiment. Thus, it is intended that the present invention covers such modifications and variations as come within the scope of the appended claims and their equivalents.

Referring now to FIGS. 1 and 2, an air conditioner unit 10 is provided. The air conditioner unit 10 is a one-unit type air conditioner, also conventionally referred to as a room air conditioner or a packaged terminal air conditioner (PTAC). The unit 10 includes an indoor portion 12 and an outdoor portion 14, and generally defines a vertical direction V, a lateral direction L, and a transverse direction T. Each direction V, L, T is perpendicular to each other, such that an orthogonal coordinate system is generally defined. Although aspects of the present subject matter are described with reference to PTAC unit 10, it should be appreciated that aspects of the present disclosure may be equally applicable to other air conditioner unit types and configurations, such as single package vertical units (SPVUs) and split heat pump systems.

A housing 20 of the unit 10 may contain various other components of the unit 10. Housing 20 may include, for example, a rear grill 22 and a room front 24 which may be spaced apart along the transverse direction T by a wall sleeve 26. The rear grill 22 may be part of the outdoor portion 14 in or adjacent to outdoor environment 18, and the room front 24 may be part of the indoor portion 12 in or adjacent to the conditioned space 28. Components of the outdoor portion 14, such as an outdoor heat exchanger 30, an outdoor fan 32, and a compressor 34 may be housed within the wall sleeve 26. A fan shroud 36 may additionally enclose outdoor fan 32, as shown to direct the flow of outside air over or through the outdoor heat exchanger 30.

Indoor portion 12 may include, for example, an indoor heat exchanger 40, a blower fan or indoor fan 42, and a supplemental heating unit 44. These components may, for example, be housed behind the room front 24. Additionally, a bulkhead 46 may generally support and/or house various other components or portions thereof of the indoor portion 12, such as indoor fan 42 and the supplemental heating unit 44. Bulkhead 46 may generally separate and define the indoor portion 12 and outdoor portion 14, and accordingly separate the outdoor environment 18 from the conditioned space 28. According to some embodiments, indoor fan 42 is a variable speed fan, for example, a variable centrifugal blower or fan as illustrated, for example in FIG. 7.

Outdoor and indoor heat exchangers 30, 40 may be components of a sealed system or refrigeration loop 48, which is shown schematically in FIG. 3. Refrigeration loop 48 may, for example, further include compressor 34 and an expansion device 50, both operably coupled to the loop 48. As illustrated, compressor 34 and expansion device 50 may be in fluid communication with outdoor heat exchanger 30 and indoor heat exchanger 40 to flow refrigerant therethrough as is generally understood. The compressor 34 is configured to urge refrigerant to flow through the refrigeration loop 48 in a refrigeration cycle. More particularly, refrigeration loop 48 may include various lines for flowing refrigerant between the various components of refrigeration loop 48, thus providing fluid communication therebetween. Refrigerant may thus flow through such lines from indoor heat exchanger 40 to compressor 34, from compressor 34 to outdoor heat exchanger 30, from outdoor heat exchanger 30 to expansion device 50, and from expansion device 50 to indoor heat exchanger 40. The refrigerant may generally undergo phase changes associated with a refrigeration cycle as it flows to and through these various components, as is generally understood. Suitable refrigerants for use in refrigeration loop 48 may include pentafluoroethane, difluoromethane, or a mixture such as R410a, although it should be understood that the present disclosure is not limited to such examples and rather that any suitable refrigerant may be utilized.

As is understood in the art, refrigeration loop 48 may be alternately operated as a refrigeration assembly (and thus perform a refrigeration cycle) or a heat pump (and thus perform a heat pump cycle). As shown in FIG. 3, when refrigeration loop 48 is operating in a cooling mode and thus performing a refrigeration cycle, the indoor heat exchanger 40 acts as an evaporator and the outdoor heat exchanger 30 acts as a condenser. Alternatively, when the refrigeration loop 48 is operating in a heating mode and thus performs a heat pump cycle, the indoor heat exchanger 40 acts as a condenser and the outdoor heat exchanger 30 acts as an evaporator. The outdoor and indoor heat exchangers 30, 40 may each include coils through which a refrigerant may flow for heat exchange purposes, as is generally understood.

According to an exemplary embodiment, compressor 34 may be a variable speed compressor. In this regard, compressor 34 may be operated at various speeds depending on the current air conditioning needs of the conditioned space 28, the demand from refrigeration loop 48, or under other conditions as determined by controller 64. For example, according to an exemplary embodiment, compressor 34 may be configured to operate at any speed between a minimum speed, e.g., about 1500 revolutions per minute (RPM), to a maximum rated speed, e.g., about 6000 RPM. Notably, use of variable speed compressor 34 enables efficient operation of refrigeration loop 48 (and thus air conditioner unit 10), minimizes unnecessary noise when compressor 34 does not need to operate at full speed, and ensures a comfortable environment within the conditioned space 28. According to some embodiments, the compressor speed may be increased or decreased, sometimes referred to as ramped up or ramped down, from a first speed to a second higher or lower speed at a predetermined compressor ramp up or ramp down rate of, for example, about 100 RPM/minute. The second speed may be a maximum compressor speed, e.g., about 6000 RPM or a minimum compressor speed, e.g., about 1500 RPM.

Specifically, according to an exemplary embodiment, compressor 34 may be an inverter compressor. In this regard, compressor 34 may include a power inverter, power electronic devices, rectifiers, or other control electronics suitable for converting an alternating current (AC) power input into a direct current (DC) power supply for the compressor. The inverter electronics may regulate the DC power output to any suitable DC voltage that corresponds to a specific operating speed of compressor 34. In this manner compressor 34 may be regulated to any suitable operating speed, e.g., from 0% to 100% of the full rated power and/or speed of the compressor. This may facilitate precise compressor operation at the desired operating power and speed, thus meeting system needs while maximizing efficiency and minimizing unnecessary system cycling, energy usage, and noise.

In an exemplary embodiment illustrated in FIG. 4, expansion device 50 may be disposed in the outdoor portion 14 between the indoor heat exchanger 40 and the outdoor heat exchanger 30. According to the exemplary embodiment, expansion device 50 may be an electronic expansion valve (“EEV”) that enables controlled expansion of refrigerant, as is known in the art. According to alternative embodiments, expansion device 50 may be a capillary tube or another suitable expansion device configured for use in a thermodynamic cycle.

More specifically, according to exemplary embodiments, the electronic expansion device EEV 50 may be configured to precisely control the expansion of refrigerant to maintain a desired temperature differential of the refrigerant across the evaporator (i.e., the outdoor heat exchanger 30 in heat pump mode). In other words, electronic expansion device 50 throttles the flow of refrigerant based on the temperature differential across the evaporator to ensure that the refrigerant is in the gaseous state entering compressor 34.

According to the illustrated exemplary embodiment, outdoor fan 32 is an axial fan and indoor fan 42 is a centrifugal fan. However, it should be appreciated that according to alternative embodiments, outdoor fan 32 and indoor fan 42 may be any suitable fan type. In addition, according to an exemplary embodiment, outdoor fan 32 and indoor fan 42 are variable speed fans. For example, outdoor fan 32 and indoor fan 42 may rotate at different rotational speeds, thereby generating different air flow rates. It may be desirable to operate fans 32, 42 at less than their maximum rated speed to ensure safe and proper operation of refrigeration loop 48 at less than its maximum rated speed, e.g., to reduce noise when full speed operation is not needed. Further, it may be desirable to separately control the operation of outdoor fan 42 to adjust the flow of outdoor makeup air 116 through the air conditioner unit 10.

According to the illustrated embodiment, indoor fan 42 may operate in refrigeration loop 48 to encourage the flow of indoor air over or through indoor heat exchanger 40. Accordingly, indoor fan 42 may be positioned downstream of indoor heat exchanger 40 along the flow direction of indoor air and downstream of a heating unit, supplemental heating unit 44, to “pull” air over or through the indoor heat exchanger 40. Alternatively, indoor fan 42 may be positioned upstream of indoor heat exchanger 40 along the flow direction of indoor air and may operate to “push” air over or through indoor heat exchanger 40 and supplemental heating unit 44.

In exemplary embodiments, heating unit or supplementary heating unit 44 includes one or more heater banks 60. Each heater bank 60 may be operated (i.e., energized) as desired to produce heat under the control of controller 64. The heater banks 60 may be electrically powered heat sources selectively energized to provide heat energy to the mixed air flow 118. In some embodiments as shown, three heater banks 60 may be utilized. Alternatively, however, any suitable number of heater banks 60 may be utilized. Each heater bank 60 may further include at least one heater coil or coil pass 62, such as in exemplary embodiments two heater coils or coil passes 62. Alternatively, other suitable heating elements may be utilized to provide supplemental heat using other energy sources.

The operation of air conditioner unit 10 including compressor 34 (and thus refrigeration loop 48 generally), indoor fan 42, outdoor fan 32, heating unit 44, expansion device 50, auxiliary fan 102, and other components of refrigeration loop 48 may be controlled by a processing device such as a controller 64 (e.g., FIGS. 1 and 3). In some embodiments, control panel 66 may include or be in operative communication with one or more user input devices 68, such as one or more of a variety of digital, analog, electrical, mechanical, or electro-mechanical input devices including rotary dials, control knobs, push buttons, toggle switches, selector switches, and touch pads. Additionally, air conditioner unit 10 may include a display 70, such as a digital or analog display device generally configured to provide visual feedback regarding the operation of unit 10. For example, display 70 may be provided on control panel 66 and may include one or more status lights, screens, or visible indicators, to communicate settings, operation status, or fault conditions with any system of the air conditioning unit 10. According to exemplary embodiments, user input devices 68 and display 70 may be integrated into a single device, e.g., including one or more of a touchscreen interface, a capacitive touch panel, a liquid crystal display (LCD), a plasma display panel (PDP), a cathode ray tube (CRT) display, or other informational or interactive displays.

Air conditioner unit 10 may further include or be in operative communication with a processing device or a controller 64 that may be generally configured to facilitate appliance operation. In this regard, control panel 66, user inputs 68, and display 70 may be in communication with controller 64 such that controller 64 may receive control inputs from user inputs 68, may display information using display 70, and may otherwise regulate operation of unit 10. In addition, controller 64 may receive signals sent or communicated by various sensors (e.g., inlet air temperature sensor 120 or discharge air temperature sensor 122) for storage in a memory location or processing in a processor. The controller 64 may communicate a response or instruction to the various systems within unit 10. For example, signals generated or communicated by controller 64 may operate unit 10, including any or all system components, subsystems, or interconnected devices, in response to the position of user input devices 68 and other control commands. Control panel 66 and other components of unit 10 may be in communication with controller 64 via, for example, one or more signal lines or shared communication busses. In this manner, Input/Output (“I/O”) signals may be routed between controller 64 and various operational components of unit 10.

As used herein, the terms “processing device,” “computing device,” “controller,” or the like may generally refer to any suitable processing device, such as a general or special purpose microprocessor, a microcontroller, an integrated circuit, an application specific integrated circuit (ASIC), a digital signal processor (DSP), a field-programmable gate array (FPGA), a logic device, one or more central processing units (CPUs), a graphics processing units (GPUs), processing units performing other specialized calculations, semiconductor devices, etc. In addition, these “controllers” are not necessarily restricted to a single element but may include any suitable number, type, and configuration of processing devices integrated in any suitable manner to facilitate appliance operation. Alternatively, controller 64 may be constructed without using a microprocessor, e.g., using a combination of discrete analog and/or digital logic circuitry (such as switches, amplifiers, integrators, comparators, flip-flops, AND/OR gates, and the like) to perform control functionality instead of relying upon software.

Controller 64 may include, or be associated with, one or more memory elements or non-transitory computer-readable storage mediums, such as RAM, ROM, EEPROM, EPROM, flash memory devices, magnetic disks, or other suitable memory devices (including combinations thereof). These memory devices may be a separate component from the processor or may be included onboard within the processor. In addition, these memory devices can store information and/or data accessible by the one or more processors, including instructions that can be executed by the one or more processors. It should be appreciated that the instructions can be software written in any suitable programming language or can be implemented in hardware. Additionally, or alternatively, the instructions can be executed logically and/or virtually using separate threads on one or more processors.

For example, controller 64 may be operable to execute programming instructions or micro-control code associated with an operating cycle of unit 10. In this regard, the instructions may be software or any set of instructions that when executed by the processing device, cause the processing device to perform operations, such as running one or more software applications, displaying a user interface, receiving user input, processing user input, etc. Moreover, it should be noted that controller 64 as disclosed herein is capable of and may be operable to perform any methods, method steps, or portions of methods as disclosed herein. For example, in some embodiments, methods disclosed herein may be embodied in programming instructions stored in the memory and executed by controller 64.

The memory devices included or coupled to controller 64 may also store data that can be retrieved, manipulated, created, or stored by the one or more processors or portions of controller 64. The data can include, for instance, data to facilitate performance of methods described herein. The data can be stored locally (e.g., on controller 64) in one or more databases and/or may be split up so that the data is stored in multiple locations. In addition, or alternatively, the one or more database(s) can be connected to controller 64 through any suitable network(s), such as through a high bandwidth local area network (LAN) or wide area network (WAN). In this regard, for example, controller 64 may further include a communication module or interface that may be used to communicate with one or more other component(s) of unit 10, controller 64, an external appliance controller, or any other suitable device, e.g., via any suitable communication lines or network(s) and using any suitable communication protocol. The communication interface can include any suitable components for interfacing with one or more network(s), including for example, transmitters, receivers, ports, controllers, antennas, or other suitable components.

Referring to FIGS. 4 and 5, a vent aperture 80 may be defined in bulkhead 46 for providing fluid communication between indoor portion 12 and outdoor portion 14. In particular, vent aperture 80 fluidly couples the outside portion 14 with plenum 16 and indoor fan 42 which is in fluid communication with both the plenum 16 and the conditioned space 28. Vent aperture 80 may be utilized in an installed air conditioner unit 10 to allow outdoor air to mix with indoor air (i.e., recirculating indoor air) in the plenum 16 adjacent to indoor fan 42, forming a mixed discharge airflow 118 for discharge into the conditioned 28 space through the discharge vent 112. In this regard, in some cases it may be desirable to allow fresh outside or outdoor air (i.e., “makeup air” 116) to flow into the conditioned space in order, e.g., to meet government regulations, to compensate for negative pressure created within the conditioned space, etc. In this manner, according to an exemplary embodiment, makeup air 116 may be provided into the space through fan assembly 100 (described below), vent aperture 80, plenum 16, and discharge vent 112 as required or when desired.

As shown in FIG. 5, a vent door or damper 82 may be pivotally mounted to the bulkhead 46 proximate to vent aperture 80 to open and close vent aperture 80. More specifically, as illustrated, damper 82 is pivotally mounted to the indoor facing surface of bulkhead 46 and pivotable towards indoor portion 12. Vent door 82 may open to a plenum 16 formed at the indoor facing side of bulkhead 46. The auxiliary fan 102 urges a flow of outdoor make-up air 116 into the plenum 16 to combine with the recirculating flow of indoor air, i.e., inlet air flow 114, to produce a mixed discharge airflow 118 that is directed through the discharge vent 112 and into the conditioned space 28. The recirculating flow of indoor air 114 and the mixed discharge airflow 118 are motivated to flow by the action of indoor fan 42 and the outdoor fan 32.

Damper 82 may be configured to pivot, i.e., is movable, between a first, closed position (FIG. 4) where damper 82 prevents air from flowing between outdoor portion 14 and plenum 16, and a second, open position where damper 82 is in an open position (as shown in FIG. 5) and allows make-up air to flow into the plenum 16. According to the illustrated embodiment (FIG. 5), damper 82 may be pivoted between the open and closed position by an electric motor 84 controlled by controller 64, or by any other suitable method. Intermediate positions, between the fully closed and the open positions are provided by the electric motor 84 in some embodiments. Other configurations of the vent aperture 80 and damper 82 may be used to selectively control the flow of make-up air 116 into the plenum 16.

Referring now to FIG. 6, an auxiliary fan assembly, fan assembly 100, will be described according to an exemplary embodiment of the present subject matter. According to the illustrated embodiment, fan assembly 100 is generally configured for urging the flow of makeup air 116 through vent aperture 80 and into the plenum 16 for combination with the flow of inlet air 114 for discharge as a mixed discharge airflow 118 into the conditioned space 28 without the assistance of an auxiliary sealed system. In some embodiments, fan assembly 100 could be used in conjunction with a make-up air module including an auxiliary sealed system (not shown; similar to refrigeration loop 48) for conditioning the flow of outdoor makeup air 116. As illustrated in FIG. 6, fan assembly 100 includes one auxiliary fan 102 for urging a flow of outdoor makeup air 116 through a fan duct 104, through vent aperture 80, to indoor fan 42. In other embodiments, more than one auxiliary fan 102 may be used, or other configurations of fan assembly 100 are provided.

According to the illustrated embodiment of FIG. 6, auxiliary fan 102 is an axial fan positioned at an inlet of fan duct 104, e.g., upstream from vent aperture 80. In embodiments, the auxiliary fan 102 may be a variable speed fan, with the fan speed controlled by the controller 64. However, it should be appreciated that any other suitable number, type, and configuration of fan or blower could be used to urge a flow of make-up air according to alternative embodiments. In addition, auxiliary fan 102 may be positioned in any other suitable location within air conditioner unit 10, and auxiliary fan 102 may be positioned at any other suitable location within or in fluid communication with fan duct 104. The embodiments described herein are exemplary and are not intended to limit the scope of the present subject matter.

Referring now to FIG. 7, operation of unit 10 will be described according to an exemplary embodiment. More specifically, the operation of components will be described during a cooling operation and a heating operation of unit 10. Moreover, although operation of unit 10 is described below for the exemplary packaged terminal air conditioner (PTAC) unit, it should be further appreciated that aspects of the present subject matter may be used in any other suitable air conditioner unit, for example single package vertical units (SPVUs).

As illustrated, room front 24 of unit 10 generally defines an intake vent 110 and a discharge vent 112 for use in circulating a flow of indoor air (indicated by arrows 114) throughout a conditioned space 28. In this regard, indoor fan 42 is generally configured for drawing in inlet air 114 through intake vent 110 and urging the flow of air over or through indoor heat exchanger 40 before discharging the inlet air 114 out of discharge vent 112. According to the illustrated embodiment, intake vent 110 is positioned proximate to the bottom of unit 10 and discharge vent 112 is positioned proximate to the top of unit 10. However, it should be appreciated that according to alternative embodiments, intake vent 110 and discharge vent 112 may have any other suitable size, shape, position, or configuration.

In some embodiments, auxiliary fan 102 draws makeup air 116 from an outdoor or outside environment 18 to provide fresh air (i.e., outdoor air) to the conditioned space 28. As illustrated in FIGS. 6 and 7, auxiliary fan 102 draws makeup air 116 from the outdoor environment 18 and directs the flow to fan assembly 100 and fan duct 104. Fan duct 104 directs the flow of makeup air 116 to the bulkhead 46 and through the vent aperture 80 when vent door 82 is in the open position (FIG. 5). The flow of makeup air continues to the plenum 16 where it mixes with recirculating indoor air, inlet air 114, to form a mixed air flow 118 for discharge into the conditioned space. In some embodiments, makeup air 116 is introduced to the flow of inlet air 114 before the inlet air 114 flows over or through the indoor heat exchanger 40. In other embodiments, for example the illustrative embodiment shown, the makeup air 116 is introduced to the flow of inlet air 114 after the inlet air 114 has flowed over or through the indoor heat exchanger 40. In either case, the mixed flow 118 is discharged to the conditioned space 28.

During a cooling cycle, refrigeration loop 48 is generally configured for urging relatively cold refrigerant through indoor heat exchanger 40 in order to lower the temperature of the flow of indoor air, inlet air 114, before discharging it back into the conditioned space 28. In this configuration, the indoor heat exchanger 40 is operating as an evaporator and the refrigerant absorbs heat energy from the air flow over or through the indoor heat exchanger 40. Heat is rejected at the outdoor heat exchanger 30, which is operating as a condenser.

In embodiments, the flow of inlet air 114 passes over or through the indoor heat exchanger 40 prior to being combined with outdoor make-up air 116 to form a mixed airflow 118 that is discharged into the conditioned space 28. Specifically, during a cooling operation, controller 64 may be provided with a cooling target temperature, e.g., as set by a user for the desired room temperature (i.e., temperature in the conditioned space). In general, components of refrigeration loop 48, outdoor fan 32, indoor fan 42, auxiliary fan 102, and other components of unit 10 operate to continuously cool the flow of indoor air, and mix the outdoor make-up air with the cooled flow of indoor air (i.e., conditioned air), until the target temperature is reached and the cooling cycle ceases. If the room temperature reaches an upper limit temperature, for example a predetermined offset from the cooling target temperature, the cooling cycle may begin again. In embodiments providing a flow of make-up air 116 to the conditioned space 28, for example using auxiliary fan 102, the auxiliary fan 102 may continuously operate independently of the cooling cycle.

During a heating cycle, the flow of refrigerant in the refrigeration loop 48 is reversed from that of the cooling cycle as known in the art. To achieve this, a reversing valve is fluidly coupled to the refrigeration loop 48 and selectively movable between a first position corresponding to the cooling mode and a second position corresponding to the heating mode. For example, relatively warm refrigerant flows from the compressor 34 into the indoor heat exchanger 40, which is operating as a condenser, to reject heat into the conditioned space 28. In some embodiments including a make-up air module having an auxiliary sealed system as described above, the auxiliary sealed system may be reversible to act as a heat pump to produce a heating cycle for the makeup air 116. In this case, the makeup air is heated prior to introduction to the inlet air 114 in the plenum 16.

In some embodiments, a supplemental heat source is provided to augment the heating capacity of the air conditioning unit 10. For units 10 used in anticipated cold environments, a supplemental heat source may be included to facilitate adequate heating for the conditioned space. For example, heater bank 60 may include one or more heater coils 62 configured to provide supplemental heat energy to the flow of recirculating inlet air 114. In an exemplary embodiment, heater coils 62 may be electric resistance heat sources controlled by controller 64. In other embodiments, other supplemental heat sources may be used.

In order to facilitate operation of refrigeration loop 48 and other components of unit 10 in a method in accordance with this disclosure, unit 10 may include sensors for detecting conditions of the inlet air flow 114 and the discharge flow of mixed air 118 supplied to the conditioned space 28 by the unit 10. These conditions can be fed to controller 64 which may make decisions regarding operation of unit 10 to rectify undesirable conditions or to otherwise condition the flow of mixed air 118 into the conditioned space 28. For example, as best illustrated in FIG. 7, unit 10 includes an inlet temperature sensor 120 which is positioned upstream (i.e., in a direction against the indoor air flow) from the indoor heat exchanger 40 to detect the temperature of the inlet air flow 114 as it enters the room front 24, i.e., before conditioning at the indoor heat exchanger 40. In addition, unit 10 includes a discharge air temperature sensor 122 which is positioned in the discharge flow of mixed air 118. The inlet and discharge air temperature sensors 120, 122 are operatively connected to the controller 64 to communicate temperature signals proportional to the sensed temperatures of the inlet air 114 and the discharge air 118, respectively.

Controller 64 processes the signals from inlet and discharge temperature sensors 120, 122 and operates the components of unit 10 to maintain conditions of a flow of mixed air 118 within a prescribed range. For example, in an embodiment, the controller receives signals from inlet and discharge temperature sensors 120, 122, and subtracts one from the other. In an embodiment, the controller 64 converts signals from inlet and discharge temperature sensors 120, 122 to corresponding temperatures, and subtracts one temperature from the other.

In the embodiment illustrated, the controller 64 determines a temperature differential formed by subtracting the mixed discharge air flow temperature from the inlet air flow temperature. In embodiments, air conditioning unit 10 is reversible, that is the refrigeration loop 48 may be operated in a cooling mode to cool the conditioned space or may be operated in a heating mode to heat the conditioned space 28. The controller 64 will use different predetermined temperature differentials in determining the operating condition of the air conditioning unit 10.

For example, in a cooling mode, the inlet air 114 is drawn in through inlet vent 110 with the inlet air temperature sensor 120 sensing the inlet air temperature. The inlet air 114 flows through the air conditioning unit 10 components as described above. Discharge air 118, comprising inlet air 114 and makeup air 116, is discharged through discharge vent 112. Discharge air temperature is sensed by discharge air temperature sensor 122. Controller 64 processes the received signals from the inlet and discharge temperature sensors 120, 122 and determines a temperature differential equivalent to the discharge air temperature subtracted from the inlet air temperature. Under proper operating conditions in the cooling mode, the temperature of the discharge air 118 is lower than the temperature of the inlet air 114. Accordingly, in a properly operating cooling mode, the differential is equal to or greater than zero. For example, the cooling mode differential may be between zero and 10 degrees Fahrenheit (° F.), or for example 5 OF. If the temperature differential is less than 0° F., i.e., the mixed discharge air temperature is greater than the inlet air temperature, the controller 64 determines that the temperature differential deviates from the prescribed range for the cooling mode differential and the controller 64 implements a responsive action.

Alternately, in a heating mode, the inlet air temperature sensor 120 and the discharge temperature sensor 122 sense the respective air temperatures and communicate signals corresponding to the temperatures to the controller 64. Controller 64 processes the received signals and determines a temperature differential equivalent to the discharge air temperature subtracted from the inlet air temperature. Under proper operating conditions in the heating mode, the temperature of the discharge air 118 is higher than the temperature of the inlet air 114. Accordingly, in a properly operating heating mode, the differential is less than or equal to zero. For example, the heating mode differential may be between zero and −10 degrees Fahrenheit (° F.), or for example −5° F. If the heating mode temperature differential is greater than 0° F., i.e., the inlet air temperature is greater than the mixed discharge air temperature, the controller 64 determines that the temperature differential deviates from the prescribed range for the heating mode differential and the controller 64 implements a responsive action.

In cases where the temperature differential deviates from the prescribed range, for either the cooling mode or the heating mode, the responsive action implemented by the controller 64 includes one or more of increasing the speed of the compressor 34, decreasing the flow rate of outdoor makeup air by decreasing the speed of the auxiliary fan 102, or turning off (i.e., de-energizing) the auxiliary fan 102 and closing the vent door 82. In addition to the above responsive actions common to both modes, an additional responsive action in the heating mode includes energizing the supplemental heat source 44 (i.e., energizing one or more heater coils 62 in the heater bank 60).

Each of the responsive actions will lessen the effect that the temperature of the outside make up air 116 will have on the conditioned space 28 if the air conditioning unit is unable to adequately condition the makeup air. In some cases, temperature extremes in the outdoor environment 18 exceed the capacity of the properly functioning air conditioning unit 10. In other cases, a fault or defect in the operation of the air conditioning unit may negatively impact the ability of the unit 10 to properly condition the makeup air 116. Regardless of the reason for inadequate conditioning of the makeup air 116, continued introduction of the makeup air would lead to occupant discomfort and dissatisfaction, and possibly damage to the structure of the conditioned space 28.

Now that the construction of air conditioner unit 10 and the configuration of controller 64 according to exemplary embodiments have been presented, an exemplary method 200 of operating a packaged terminal air conditioner unit will be described. Referring to FIG. 8, method 200 includes, at step 202, operating a compressor in an air conditioner unit 10 at a first compressor speed. In this regard, continuing from the above example, the controller 64 is in operative communication with the compressor 34 and may operate the compressor 34 at a default speed measured in revolutions per minute (RPM). The default speed may have been determined or calculated to produce sufficient cooling capacity under a particular set of conditions. As above, the compressor urges the flow of working fluid, or refrigerant, through the refrigeration loop 48 shown schematically in FIG. 3.

The method further includes, at step 204, operating an indoor fan 42 at a first fan speed. The indoor fan 42 is in operative communication with the controller 64 and may be initially operated at a default speed measured in revolutions per minute (RPM). The indoor fan 42 may be a variable speed fan operable at more than one speed, the fan speed provided at the instruction of the controller 64. Indoor fan 42 is operable to urge, or draw, an inlet air flow 114 into intake vent 110 at the lower portion of the room front 24 of air conditioner unit 10. The indoor fan 42 further urges the inlet air flow 114 across indoor heat exchanger 40. In the cooling mode, indoor heat exchanger 40 is an evaporator. Conversely, in the heating mode, indoor heat exchanger 40 is a condenser. The inlet air flow 114 continues into the plenum 16 formed at the indoor facing side of the bulkhead 46 with the plenum in fluid communication with indoor fan 42. After passing through the plenum 16, the recirculating flow of indoor air 114 passes through the discharge vent 112 and into the conditioned space.

At 206, method 200 operates an auxiliary fan 102 at a first auxiliary fan speed to urge a flow of outdoor (make-up) air 116 to the plenum 16. According to some embodiments, auxiliary fan 102 may be a variable speed fan and may therefore provide various air flow rates of make-up air. In some embodiments, the auxiliary fan urges a continuous flow of make-up air into the plenum 16 regardless of the off/on status of the refrigeration loop 48. The auxiliary fan urges the flow of outdoor air, or make-up air, 116 to combine with the recirculating flow of indoor air 114 in the plenum 16 to produce a mixed airflow 118. The airflows (indoor air 114 and make-up or outdoor air 116) are combined together to form a mixed air flow 118 to be discharged into the conditioned space 28 through the discharge vent 112.

At 208, the controller 64 determines the temperature of the inlet flow of indoor air 114 from the conditioned space 28 and the temperature of the mixed discharge air flow 118. As illustrated in FIG. 7, inlet air flow temperature sensor 120 is positioned in the intake vent 110 to sense the temperature of the inlet air flow 114 before conditioning by the indoor heat exchanger 40. FIG. 7 also illustrates the discharge air temperature sensor 122 positioned in the discharge vent 112, configured to sense the temperature of the discharge flow of mixed air 118. The inlet and discharge air temperature sensors 120, 122 are in operable communication with the controller 64 and communicate to the controller signals corresponding to the temperature of the inlet air flow 114 and the mixed discharge air flow 118, respectively.

At 210 the temperature differential is calculated between the temperature of the inlet air flow 114 and the temperature of the discharge flow of mixed air 118 by subtracting the temperature of the discharge air flow from the temperature of the inlet air flow. The differential may be determined by subtracting the signals from the inlet and discharge air temperature sensors 120, 122 or processing the signals to yield corresponding temperatures and processing the corresponding temperatures to yield the temperature differential. The controller 64 includes a predetermined temperature differential, which may be a single value or a range of values, corresponding to anticipated or acceptable performance of the unit 10. In embodiments, the controller 64 includes two predetermined differentials, a cooling mode temperature differential and a heating mode temperature differential, with the specific differential to be used during the corresponding mode of operation of the unit 10. For example, the cooling mode differential may be between zero and 10° F., or for example 5° F. and the heating mode differential may be between zero and −10° F., or for example −5° F. If the determined temperature differential deviates from the predetermined differential for the operating mode, controller 64 may signal a fault and proceed to step 212.

At 212, a responsive action is implemented in response to the determination that the determined temperature differential deviates from the predetermined differential. In embodiments, the compressor 34 is a variable speed compressor. In such a case, the responsive action may include increasing the operating speed of the compressor 34 to increase the thermal performance of the refrigeration loop 48. In some embodiments, the auxiliary fan 102 is a variable speed fan. In such embodiments, the responsive action may be to decrease the speed of the auxiliary fan from a first speed to a second speed. In doing so, the mass flow of outdoor makeup air will be reduced. In some cases, the speed of the auxiliary fan may be reduced to zero by de-energizing the auxiliary fan 102. The vent door 82 may be closed to prevent any flow of outdoor makeup air into the unit 10. In the heating mode, an additional responsive action includes energizing the supplemental heat source 44, for example by applying electrical energy to one or more heater coils 62 in the heater bank 60.

FIG. 9 represents a flow chart illustrating a method of operation 300 for an exemplary air conditioner unit in a cooling mode. At steps 302 and 304, the inlet air temperature and discharge air temperature are measured, for example using inlet and discharge air temperature sensors 120, 122. At 306, the temperatures are evaluated to determine if the discharge temperature is less than the inlet temperature. If yes (308), the cooling operation continues (310). If no (312) the cooling output is increased at 314 by increasing the compressor speed. At 316 and 318, the inlet and discharge temperatures are again measured and evaluated at 320 to determine if the discharge temperature is less than the inlet temperature. If yes (322), the method returns to 302. If no (324), the makeup air (MUA) fan speed is decreased at 326. At 328 and 330, the inlet and discharge temperatures are again measured and evaluated at 332 to determine if the discharge temperature is less than the inlet temperature. If yes (334), the method returns to 302. If no (336), the makeup air (MUA) fan is turned off (i.e., de-energized) and the damper or vent door 82 is closed at 338.

FIG. 10 represents a flow chart illustrating a method of operation 400 of an exemplary air conditioner unit in a heating mode. At steps 402 and 404, the inlet air temperature and discharge air temperature are measured, for example using inlet and discharge air temperature sensors 120, 122. At 406, the temperatures are evaluated to determine if the discharge temperature is greater than the inlet temperature. If yes (408), the heating operation continues (410). If no (412) the heating output is increased at 414 by increasing the compressor speed or providing electrical heat, for example with supplemental heat source 44. At 416 and 418, the inlet and discharge temperatures are again measured and evaluated at 420 to determine if the discharge temperature is greater than the inlet temperature. If yes (422), the method returns to 402. If no (424), the makeup air (MUA) fan speed is decreased at 426. At 428 and 430, the inlet and discharge temperatures are again measured and evaluated at 432 to determine if the discharge temperature is greater than the inlet temperature. If yes (434), the method returns to 402. If no (436), the makeup air (MUA) fan is turned off (i.e., de-energized) and the damper or vent door 82 is closed at 438.

This written description uses examples to disclose the invention, including the best mode, and also to enable any person skilled in the art to practice the invention, including making and using any devices or systems and performing any incorporated methods. The patentable scope of the invention is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they include structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal language of the claims.