Capacity sensing for an air conditioning appliance over time

Abstract

A method of capacity sensing in an AC unit is provided. The method includes determining an airflow rate through the AC unit. The method also includes determining a temperature difference between a pair of discrete points along an airflow path of the AC unit. The method further includes determining a measured capacity value based on the temperature difference. The method also includes determining a variation value between the measured capacity value and a predetermined capacity value. The method further includes determining a fault status based on the variation value. The method still further includes initiating a status indicator from the AC unit based on the fault status.

Description

FIELD OF THE DISCLOSURE

[0001] The present subject matter relates generally to air conditioning appliances, and more particularly to air conditioning units and methods for capacity sensing over time.BACKGROUND OF THE DISCLOSURE

[0002] Air conditioner (AC) units are conventionally utilized to adjust the temperature within structures such as dwellings and office buildings. In particular, one-unit type room air conditioner units may be utilized to adjust the temperature in, for example, a single room or group of rooms of a structure. A typical one-unit type air conditioner or air conditioning appliance includes an indoor portion and an outdoor portion. The indoor portion is generally located indoors, and the outdoor portion is generally located outdoors. Accordingly, the air conditioner unit generally extends through, for example, a wall of the structure. Generally, a fan may be operable to rotate to motivate air through the indoor portion. Another fan may be operable to rotate to motivate air through the outdoor portion. A sealed cooling system including a compressor is generally housed within the air conditioner unit to treat (e.g., cool or heat) air as it is circulated through, for example, the indoor portion of the air conditioner unit. One or more control boards are typically provided to direct the operation of various elements of the particular air conditioner unit.

[0003] Upon installation, the AC unit may have a certain thermal (e.g., cooling or heating) capacity. The cooling capacity is a measurement or calculation of the AC unit's cooling ability or the amount of heat the AC unit can remove from an area. Over time, this cooling capacity can degrade from the cooling capacity upon installation. Often there is no way to avoid the degrading of the capacity as it is a common effect that occurs from AC unit functions. However, this may lead to a number of issues for a user. For instance, in many cases, a user may perceive that performance has degraded, but not understand that it is a function of cooling capacity. Such a determination may only be possible by a service technician. Specifically, a service technician may be required to measure the outflow temperatures of the AC unit to determine the current capacity. This may require a service call between the customer and provider as well as a visit by the service technician to take the measurements. The service call and visit can not only generate additional costs, but also may decrease overall customer satisfaction.

[0004] Although it may be desirable to anticipate a decrease in functionality, this presents some challenges. For instance, the ability to remotely measure the capacity of the AC unit would be helpful, but present remote measurement systems involve the use of multiple additional components which may serve costly for the provider to maintain and run in the AC unit. The addition of multiple sensors may also affect other components of the AC unit or the AC unit environment as a whole (e.g., heat dissipated by multiple added sensors may heat the environment of the AC unit to a temperature higher than the usual temperature of the AC unit environment). Increasing the temperature of the AC unit environment may cause certain operations based on temperature readings within the environment to perform inconsistently. More sensors may also increase the likelihood of a potential failure or fault in the equipment.

[0005] As a result, further improvements would be useful, such as to ensure consistent or reliable operation of an air conditioning appliance.BRIEF DESCRIPTION OF THE DISCLOSURE

[0006] Aspects and advantages of the invention will be set forth in part in the following description, or may be obvious from the description, or may be learned through practice of the invention.

[0007] In one exemplary aspect of the present disclosure, a method of capacity sensing in an AC unit is provided. The method may include determining an airflow rate through the AC unit. The method may also include determining a temperature difference between a pair of discrete points along an airflow path of the AC unit. The method may further include determining a measured capacity value based on the temperature difference. The method may also include determining a variation value between the measured capacity value and a predetermined capacity value. The method may further include determining a fault status based on the variation value. The method may still further include initiating a status indicator from the AC unit based on the fault status.

[0008] In another exemplary aspect of the present disclosure, an AC unit is provided. The AC unit may include a housing unit, a sealed refrigerative system, an interior fan, a first thermistor, a second thermistor, and a controller. The sealed refrigerative system may be housed in the housing unit. The interior fan may provide airflow through the AC unit. The interior fan may also be housed within the housing unit and in connection with the sealed refrigerative system to supply airflow across the sealed refrigerative system. The first thermistor may be positioned at a first discrete point of a pair of discrete points. The second thermistor may be positioned at a second discrete point of the pair of discrete points. The controller may be configured to direct a conditioning operation. The conditioning operation may include determining an airflow rate through the AC unit. The conditioning operation may also include determining a temperature difference between a pair of discrete points along an airflow path of the AC unit. The conditioning operation may further include determining a measured capacity value based on the temperature difference. The conditioning operation may also include determining a variation value between the measured capacity value and a predetermined capacity value. The conditioning operation may further include determining a fault status based on the variation value. The conditioning operation may still further include initiating a status indicator from the AC unit based on the fault status.

[0009] 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

[0010] 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.

[0011] FIG. 1 provides a perspective view of an air conditioner unit, with a room front exploded from a remainder of the air conditioner unit for illustrative purposes, in accordance with exemplary embodiments of the present disclosure.

[0012] FIG. 2 is a perspective view of components of an indoor portion of an air conditioner unit in accordance with exemplary embodiments of the present disclosure.

[0013] FIG. 3 is a schematic view of a refrigeration loop in accordance with one embodiment of the present disclosure.

[0014] FIG. 4 provides a flow chart illustrating the combination of components needed to measure a capacity variation value and determine a fault status.

[0015] FIG. 5 provides a flow chart illustrating a method of remote capacity sensing in an AC unit.

[0016] 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

[0017] 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 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.

[0018] As used herein, the term “or” is generally intended to be inclusive (i.e., “A or B” is intended to mean “A or B or both”). The phrase “in one embodiment,” does not necessarily refer to the same embodiment, although it may. 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.

[0019] 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 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.

[0020] Referring now to the figures, in FIGS. 1 through 2, an air conditioner 10 according to various exemplary embodiments is provided. The air conditioner 10 is generally a one-unit type air conditioner, also conventionally referred to as a room air conditioner or package terminal air conditioner unit (PTAC). The air conditioner 10 includes an indoor portion 12 and an outdoor portion 14, and 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.

[0021] Although described in the context of a PTAC, an air conditioner unit as disclosed herein may be provided as a window unit, single-package vertical unit (SPVU), vertical packaged air conditioner (VPAC), mini-split air conditioner, or any other suitable single-package air conditioner. The air conditioner 10 is intended only as an exemplary unit and does not otherwise limit the scope of the present disclosure. Thus, it is understood that the present disclosure may be equally applicable to other types of air conditioner units.

[0022] Generally, a housing 20 of the unit 10 contains various other components of the unit 10. Housing 20 may include, for example, a rear grill 22 and a room front 24 that 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, while the room front 24 is part of the indoor portion 12. Components of the outdoor portion 14 such as an outdoor heat exchanger 30, outdoor fan 32, and compressor 34 may be housed within the wall sleeve 26. A casing may additionally enclose the outdoor fan 32, as shown.

[0023] Referring now also to FIG. 2, indoor portion 12 may include, for example, an indoor heat exchanger 40, a blower fan 42, and a heating unit 44. These components may, for example, be housed behind the room front 24. Additionally, a bulkhead 46 may generally support or house various other components or portions thereof of the indoor portion 12, such as the blower fan 42 and the heating unit 44. Bulkhead 46 may generally separate and define the indoor portion 12 and outdoor portion 14.

[0024] Outdoor and indoor heat exchangers 30, 40 may be components of a thermodynamic assembly (i.e., sealed system), which may be operated as a refrigeration assembly (and thus perform a refrigeration cycle) and, in the case of the heat pump unit embodiment, a heat pump (and thus perform a heat pump cycle). Thus, as is understood, exemplary heat pump unit embodiments may be selectively operated to perform a refrigeration cycle at certain instances (e.g., while in a cooling mode) and a heat pump cycle at other instances (e.g., while in a heating mode). By contrast, exemplary A / C exclusive unit embodiments may be unable to perform a refrigeration cycle (e.g., while in a cooling mode).

[0025] The sealed system or assembly may, for example, further include compressor 34 and an expansion valve, both of which may be in fluid communication with the heat exchangers 30, 40 to flow refrigerant therethrough, as is generally understood. Optionally, the compressor 34 may be a variable speed compressor or, alternatively, a single speed compressor. When the assembly is operating in a cooling mode, and thus performs a refrigeration cycle, the indoor heat exchanger 40 acts as an evaporator and the outdoor heat exchanger 30 acts as a condenser. In heat pump unit embodiments, when the assembly 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 31, 41, as illustrated, through which a refrigerant may flow for heat exchange purposes, as is generally understood. For instance, and as will be understood, in response to an input temperature setting, compressor 34 may activate for a cycle (e.g., cooling cycle or heating cycle) until the input temperature setting (or hysteresis thereof) is detected within the corresponding room.

[0026] Bulkhead 46 may include various peripheral surfaces that define an interior thereof. For example, and additionally referring to FIG. 3, bulkhead 46 may include a first sidewall 52 and a second sidewall 54 which are spaced apart from each other along the lateral direction L. A rear wall 56 may extend laterally between the first sidewall 52 and second sidewall 54.

[0027] The rear wall 56 may, for example, include an upper portion and a lower portion. The upper portion may for example have a generally curvilinear cross-sectional shape, and may accommodate a portion of the blower fan 42 when blower fan 42 is housed within the interior. The lower portion may have a generally linear cross-sectional shape, and may be positioned below the upper portion along the vertical direction V. Rear wall 56 may further include an indoor facing surface 64 and an opposing outdoor facing surface. The indoor facing surface 64 may face the interior and indoor portion 12, and the outdoor facing surface may face the outdoor portion 14.

[0028] Bulkhead 46 may additionally include, for example, an air diverter 68, which may extend between the sidewalls 52, 54 along the lateral direction L and through which air may flow.

[0029] In exemplary embodiments, blower fan 42 may be a tangential fan. Alternatively, however, any suitable fan type may be utilized. Blower fan 42 may include a blade assembly 70 and a motor 72. The blade assembly 70, which may include one or more blades disposed within a fan housing 74, may be disposed at least partially within the interior of the bulkhead 46, such as within the upper portion. As shown, blade assembly 70 may for example extend along the lateral direction L between the first sidewall 52 and the second sidewall 54. The motor 72 may be connected to the blade assembly 70, such as through the fan housing 74 to the blades via a shaft. Operation of the motor 72 may rotate the blades, thus generally operating the blower fan 42 (e.g., in a cooling mode, heating mode, or fan-only mode). Further, in exemplary embodiments, motor 72 may be disposed exterior to the bulkhead 46. Accordingly, the shaft may for example extend through one of the sidewalls 52, 54 to connect the motor 72 and blade assembly 70.

[0030] In exemplary embodiments, heating unit 44 includes one or more heater banks 80. Each heater bank 80 may be operated as desired to produce heat. In some embodiments, three heater banks 80 may be utilized, as shown. Alternatively, however, any suitable number of heater banks 80 may be utilized. Each heater bank 80 may further include at least one heater coil or coil pass 82, such as in exemplary embodiments two heater coils or coil passes 82. Alternatively, other suitable heating elements may be utilized. As is understood, each heater coil pass 82 may be provided as a resistive heating element configured to generate heat in response to resistance to an electrical current flowed therethrough. For instance, and as will be understood, in response to an input temperature setting, at least a portion of heater bank 80 may activate as an electrical current is flowed therethrough for a heating cycle until the input temperature setting (or hysteresis thereof) is detected within the corresponding room.

[0031] The operation of air conditioner 10, including compressor 34 (and thus the sealed system generally), blower fan 42, outdoor fan 32, heating unit 44, and other suitable components, may be controlled by a control board or controller 85. Controller 85 may be in communication (via for example a suitable wired or wireless connection) to such components of the air conditioner 10. By way of example, the controller 85 may include a memory and one or more processing devices such as microprocessors, CPUs or the like, such as general or special purpose microprocessors operable to execute programming instructions or micro-control code associated with operation of air conditioner 10. The memory may be a separate component from the processor or may be included onboard within the processor. The memory may represent random access memory such as DRAM, or read only memory such as ROM or FLASH. Generally, the processor executes programming instructions stored in memory.

[0032] Air conditioner 10 may additionally include a control panel 87 and one or more user inputs 89, which may be included in control panel 87. The user inputs 89 may be in communication with the controller 85. A user of the air conditioner 10 may interact with the user inputs 89 to operate the air conditioner 10, and user commands may be transmitted between the user inputs 89 and controller 85 to facilitate operation of the air conditioner 10 based on such user commands (e.g., to specify a desired temperature, cooling mode, heating mode, fan-only mode, idle mode, date / time, service event, etc.). A display 88 may additionally be provided in the control panel 87 and may be in communication with the controller 85. Display 88 may, for example be a touchscreen or other text-readable display screen, or alternatively may simply be a light that can be activated and deactivated as required to provide an indication of, for example, an event, setting, or mode for the air conditioner 10.

[0033] Referring now to FIG. 1, in some embodiments, a first indoor temperature sensor 92 (e.g., indoor refrigerant temperature sensor) or a second indoor temperature sensor 94 (e.g., indoor ambient temperature sensor) is disposed within the indoor portion 12, such that the first indoor temperature sensor 92 and second indoor temperature sensor 94 are both positioned in an airflow path. Each temperature sensor may be configured to sense the temperature of its surroundings. For example, each temperature sensor may be a thermistor or a thermocouple. The indoor temperature sensors 92 and 94 may be in communication with the controller 85, and may transmit temperatures sensed thereby to the controller 85 (e.g., as one or more voltages or signals, which the controller 85 is configured to interpret as temperature values). Optionally, the voltages or signal transmitted to the controller 85 may be transmitted in response to a polling request or signal received by one or more of the indoor temperature sensors 92 and 94. For example, a polling request or signal may be transmitted to one or more of the indoor temperature sensors 92, 94 from the controller 85.

[0034] First indoor temperature sensor 92 may be disposed proximate to the indoor heat exchanger 40 (such as relative to the second indoor temperature sensor 94). For example, in some embodiments, first indoor temperature sensor 92 may be in downstream fluid communication with the indoor heat exchanger 40, such as with a coil 41 thereof. In particular, the first indoor temperature sensor 92 may be located in a path of an airflow produced by blower fan 42. The first indoor temperature sensor 92 may be configured to detect a temperature for air apart from the indoor heat exchanger 40. Second indoor temperature sensor 94 may be spaced from the indoor heat exchanger 40, such as in the transverse direction T. For example, the second indoor temperature sensor 94 may be in contact with the room front 24, as illustrated in FIG. 1. Second indoor temperature sensor 94 may be configured to detect a temperature of air entering the indoor portion 12, such as in the path of the airflow produced by blower fan 42, but at a different location than the first indoor temperature sensor 92. During certain operations (e.g., in a cooling mode), air may thus generally flow across or adjacent to the second indoor temperature sensor 94, then the first indoor temperature sensor 92.

[0035] Referring again to FIG. 1, some embodiments, such as exemplary heat pump unit embodiments, a first outdoor temperature sensor 132 (e.g., outdoor refrigerant temperature sensor) (as indicated in phantom lines) and a second outdoor temperature sensor 134 (e.g., outdoor ambient temperature sensor) (as indicated in phantom lines) are disposed within the outdoor portion 14. Each temperature sensor may be configured to sense the temperature of its surroundings. For example, each temperature sensor may be a thermistor or a thermocouple. The outdoor temperature sensors 132, 134 may be in communication with the controller 85, and may transmit temperatures sensed thereby to the controller 85 (e.g., as one or more voltage signals, which the controller 85 is configured to interpret as temperature readings).

[0036] 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. 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. More particularly, refrigeration loop 48 may include various lines for flowing refrigerant between the various components of refrigeration loop 48, thus providing the fluid communication there between. 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.

[0037] 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 assembly 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.

[0038] According to an example 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 room and the demand from refrigeration loop 48. For example, according to an exemplary embodiment, compressor 34 may be configured to operate at any speed between a minimum speed, e.g., 1500 revolutions per minute (RPM), to a maximum rated speed, e.g., 3500 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 room.

[0039] 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. 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.

[0040] In exemplary embodiments as illustrated, 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.

[0041] More specifically, according to exemplary embodiments, electronic expansion device 50 may be configured to precisely control the expansion of refrigerant to maintain, for example, 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 reaction of the temperature differential across the evaporator or the amount of superheat temperature differential, thereby ensuring that the refrigerant is in the gaseous state entering compressor 34.

[0042] In general, the terms “superheat,”“operating superheat,” or the like are generally intended to refer to the temperature increase of the refrigerant past the fully saturated vapor temperature in the evaporator. In this regard, for example, the superheat may be quantified in degrees Fahrenheit, e.g., such that 1° F. superheat means that the refrigerant exiting the evaporator is 1° F. higher than the saturated vapor temperature. It should be appreciated that the operating superheat may be measured and monitored by controller 85 in any suitable manner. For example, controller 85 may be operably coupled to a pressure sensor for measuring the refrigerant pressure exiting the evaporator, may convert that pressure to the saturated vapor temperature, and may subtract that temperature from the measured refrigerant temperature at the evaporator outlet to determine superheat.

[0043] According to exemplary embodiments, expansion device or electronic expansion valve 50 may be driven by a stepper motor or other drive mechanism to any desirable position between a fully closed position (e.g., when no refrigerant passes through EEV 50) to a fully open position (e.g., when there is little or no restriction through the EEV 50). For example, controller 85 may be operably coupled to EEV 50 and may regulate the position of the EEV 50 through a control signal to achieve a target superheat, a target restriction / expansion, etc.

[0044] More specifically, the control signal communicated from controller 85 may specify the number of control steps (or simply “steps”) and a corresponding direction (e.g., counterclockwise toward the closed position or clockwise toward the open position). Each EEV 50 may have a physical stroke span equal to the difference between the fully open position and the fully closed position. In addition, the EEV 50 may include a step range or range of control steps that correspond to the number adjustment steps it takes for the EEV 50 to travel from the fully closed position to the fully open position.

[0045] Each “step” may refer to a predetermined rotation of the drive mechanism, e.g., such as a stepper motor, which may in turn move the EEV 50 a fixed linear distance toward the open or closed position (depending on the commanded step direction). For example, according to the exemplary embodiment, the EEV 50 may have a step range of 500 steps, with 0 steps corresponding to fully closed and 500 steps corresponding to fully open. However, it should be appreciated that according to alternative embodiments, any given electronic expansion valve may include a different number of control steps, and the absolute step adjustments described herein may be varied accordingly.

[0046] In addition, as used herein, the position of EEV 50 may be expressed as a percentage, e.g., where 0% corresponds to a fully closed position and 100% corresponds to a fully open position. According to exemplary embodiments, this percentage representation may also refer to the percentage of total control steps taken from the closed position, e.g., with 10% referring to 50 steps (e.g., 10% of the 500 total steps), 80% referring to 400 steps (e.g., 80% of 500 total steps), etc.

[0047] 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, e.g., similar to variable speed compressor 34. 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. In addition, according to alternative embodiments, fans 32, 42 may be operated to urge make-up air into the room.

[0048] According to the illustrated embodiment, indoor fan 42 may operate as an evaporator fan in refrigeration loop 48 to encourage the flow of air 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 heating unit 44. 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 through indoor heat exchanger 40.

[0049] Heating unit 44 in exemplary embodiments includes one or more heater banks 60. Each heater bank 60 may be operated as desired to produce heat. 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.

[0050] 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, and other components of refrigeration loop 48 may be controlled by a processing device such as a controller 85. Controller 85 may be in communication (via for example a suitable wired or wireless connection) to such components of the air conditioner unit 10. Controller 85 may include a memory and one or more processing devices such as microprocessors, CPUs or the like, such as general or special purpose microprocessors operable to execute programming instructions or micro-control code associated with operation of unit 10. The memory may represent random access memory such as DRAM, or read only memory such as ROM or FLASH. In one embodiment, the processor executes programming instructions stored in memory. The memory may be a separate component from the processor or may be included onboard within the processor.

[0051] Unit 10 may additionally include a control panel 66 and one or more user inputs 89, which may be included in control panel 66. The user inputs 89 may be in communication with the controller 85. A user of the unit 10 may interact with the user inputs 89 to operate the unit 10, and user commands may be transmitted between the user inputs 89 and controller 85 to facilitate operation of the unit 10 based on such user commands. A display 88 may additionally be provided in the control panel 66 and may be in communication with the controller 85. Display 88 may, for example be a touchscreen or other text-readable display screen, or alternatively may simply be a light that can be activated and deactivated as required to provide an indication of, for example, an event or setting for the unit 10.

[0052] FIG. 4 represents an example flowchart 400 representing an exemplary method for determining thermal capacity percent difference through the use of AC unit components accessible by a controller of the AC unit. The flowchart 400 comprises a plurality of measurements and values, wherein the measurements and values are categorized based on how each one is determined. For example, elements in a dashed box outline 450 represent values actively measured from the AC unit (e.g., measured revolutions per minute (RPM) 402, inlet air temperature 406, outlet air temperature 420, etc.). Elements in a dotted box outline 452 represent predetermined constant values and correlations stored in a look up table to be accessed by the controller (e.g., lab data volumetric flow rate (CFM) and lab data RPM 404, empirical correlation 408, lab data correlated table 428, etc.). Further, elements in a solid box outline represent values that are calculated based on the elements in dashed and dotted box outlines through the use of equations. The elements of flowchart 400 are arranged from left to right in order of earliest determination, such that elements further left on flowchart 400 are determined first and elements further right on flowchart 400 may be based on yet to be determined values and thus must be determined later in the method.

[0053] The flowchart 400 includes measuring a current fan speed 402 (RPM2) via a controller. The controller may also access provided lab data indicative of a constant volumetric flowrate (CFM1) value and a provided fan speed (RPM1) 404 (e.g., provided fan speed value), wherein the lab data may be “look up” data embedded in the AC unit. The current fan speed 402 (RPM2), provided fan speed (RPM1) 404, and provided volumetric flow rate (CFM1) 404 are used to calculate a current volumetric flow rate 412 (CFM2) of the AC unit using Equation 442:CFM2=CFM1*(RPM2 / RPM1)

[0054] The flowchart 400 also includes measuring an inlet air temperature 406 (e.g., contemporary inlet air temperature) via a first temperature sensor. The measured inlet air temperature 406 may then be converted to an air density value 410 (ρ) via a conversion rate 408 (e.g., empirical correlation) between temperature and air density. The conversion rate 408 may be a rate of about 1% to about 3 degrees Celsius. Using the conversion rate 408 may notably eliminate the need for an extra sensor to determine air density. Following the conversion, the density value 410 (ρ) and current volumetric flow rate 412 (CFM2) value can be used to determine a mass flow rate 414 (m). The mass flow rate 414 (m) is described as an amount of mass that passes per unit of time. Thus, in this embodiment, the mass flow rate 414 (m) describes the amount of air, in mass, that passes a position (e.g., the first temperature sensor). The mass flow rate 414 (m) of air may be determined using Equation 444:m=CFM2*ρ

[0055] Flowchart 400 further includes a process for determining a capacity of the AC unit. The controller may compare a measured inlet temperature 418 and a measured outlet temperature 420 (e.g., including first indoor temperature sensor 92—FIG. 1 and second indoor temperature sensor 94—FIG. 1, respectively) to determine a change in temperature readings 422 (dT). The change in temperature readings 422 (dT) represents the change in the measured readings of the airflow at the inlet temperature sensor compared to the readings of the airflow at the outlet temperature sensor. Further, a specific heat value 416 (Cp) (e.g., an isochoric specific heat of air) may be acquired by the controller. The isochoric specific heat of air represents a specific amount of heat required to change the temperature of a mass unit of air by one degree, wherein the air is in a constant-volume system. While the AC unit may not be a precisely constant-volume system, the isochoric specific heat may provide accurate results. The change in temperature readings 422 (dT), the mass flow rate 414 (m), and the specific heat value 416 (Cp) can then be used in combination to calculate an actual measured capacity 424 (Qactual) of the AC unit using Equation 446:Qactual=m*Cp*dT

[0056] Flowchart 400 further includes measuring an ambient outdoor temperature 432 (e.g., including outdoor temperature sensor 134—FIG. 1) and compressor speed 430 of the outdoor unit. In one embodiment, the measured ambient outdoor temperature 432 and outdoor compressor speed 430 are then compared to a table 428, wherein the table 428 houses a plurality of theoretical capacity values and the relationships of theoretical capacity values to actual outdoor temperatures and compressor speeds. Referring to this table 428, the controller may look up what theoretical capacity value is associated with the measured outdoor temperature 432 and measured compressor speed 430 to determine a particular theoretical capacity value 426 (Qtheoretical).

[0057] Upon calculating the actual measured capacity value 424 (Qactual) and determining the theoretical capacity value 426 (Qtheoretical), the two may be used to calculate a capacity percent error 434 (Qerror). The capacity percent error 434 (Qerror) represents a percent difference between the actual measured capacity value 424 (Qactual) and the theoretical capacity value 426 (Qtheoretical), which may be used to determine an amount that the AC unit thermal capacity alters from an efficient thermal capacity. The capacity percent error 434 (Qerror) may be calculated using Equation 448:Qerror=((|Qactual−Qtheoretical|) / Qtheoretical)*100%

[0058] Flowchart 400 further includes comparing the capacity percent error value 434 (Qerror) to a predetermined threshold percentage 436. In this embodiment, if the capacity percent error value 434 (Qerror) is less than the predetermined threshold percentage 436, the AC unit's current capacity is considered to be at a sufficient quality and there is no fault detected 440. If the capacity percent error value 434 (Qerror) is greater than the predetermined threshold percentage 436, the AC unit's current capacity is considered to be at a low enough quality and a fault is detected 438.

[0059] Referring now to FIG. 5, the present disclosure may further be directed to a method of measuring a thermal capacity of an air conditioner or air conditioner appliance, such as air conditioner 10, to determine a status of the air conditioner 10.

[0060] It is noted that the order of steps within method 500 is for illustrative purposes. All may be adopted or characterized as being fulfilled in a common operation. Except as otherwise indicated, one or more steps in the below method 500 may be changed, rearranged, performed in a different order, or otherwise modified without deviating from the scope of the present disclosure.

[0061] The method 500 may occur as, or as part of, a conditioner operation (e.g., a cooling or heating operation) of the air conditioner 10. In particular, the methods disclosed herein may advantageously adapt detection or performance of a specific air conditioner unit according to the room, environment, or location in which the unit is installed and thus continues to operate.

[0062] At 510 method 500 includes determining an airflow rate through an AC unit (e.g., volumetric flow rate as described above). As an example, the airflow rate of the AC unit may be determined, at least in part, based on a detected fan speed (e.g., in RPM). For instance, a controller may be coupled to a motor of a blower fan. The controller may access information or receive (e.g., voltage) signals from the motor indicative of an operation setting of the fan (e.g., blower fan operating at maximum capacity, blower fan speed decreasing, blower fan not currently operating, blower fan speed increasing, etc.). One or more remaining variables may be provided by pre-determined constant values (e.g., as described above). The real-time measurement of the fan speed and the pre-determined variables may be used to determine the current airflow rate of the AC unit since airflow of a fan is directly proportional to the change in the rotational speed of the fan. Thus, by determining the change in the fan speed, the change in the airflow rate can also be determined. Optionally, a detected fan speed may be the only real-time measurement needed for determining the airflow rate.

[0063] In one embodiment, the airflow rate includes or is provided as a mass flow rate. For instance, the mass flow rate may be determined by multiplying a volumetric flow rate of the AC unit by an air density value. The air density value may in turn be determined by measuring a point temperature at a discrete first point of the pair of discrete points and converting the air temperature value to an air density value. Step 510 may notably allow for the determination of the current airflow rate, without the need for an additional sensor or measurement. Fewer sensors / measurements may result in lower operational cost as well as simplifying the AC unit environment which may lead to a lower likelihood of system faults.

[0064] At 512, the method 500 includes determining a temperature difference between a pair of discrete points along an airflow path of the AC unit. The discrete points may be placed in such a way that a first temperature sensor (e.g., including first indoor temperature sensor 92—FIG. 1) is placed at a first discrete point near an outlet of the AC unit (e.g., at an outlet vent grill) and configured to measure the temperature of the airflow produced from the blower fan. A second temperature sensor (e.g., including second indoor temperature sensor 94—FIG. 1) may be placed at a second discrete point near an inlet of a coil and configured to measure the temperature of the airflow at a separate location from the first temperature sensor. The temperature difference may then be calculated by subtracting the temperature at the second discrete point from the temperature at the first discrete point. The temperature difference may comprise the difference between an inlet air temperature and an outlet air temperature.

[0065] At 514, the method 500 includes determining a measured capacity value based on the temperature difference. The measured capacity of an AC unit may refer to a current thermal capacity of the AC unit (e.g., cooling capacity or heating capacity). In one embodiment, the determined airflow rate and determined temperature difference may be used to calculate a measured capacity of the AC unit. In another embodiment, an arbitrary flow rate may be provided and thus only a measured temperature difference is needed to determine the capacitance. In another example, a specific heat value for air may also be needed to calculate the measured capacity. The measured capacity may naturally deteriorate over time (e.g., due to decreased functionality of specific components of the unit or the unit as a whole).

[0066] At 516, the method 500 includes determining a variation value between the measured capacity and a predetermined capacity value. Upon determining the current measured capacity of the AC unit, the measured capacity value may be compared to a predetermined capacity value in order to determine how much the measured capacity varies from the predetermined capacity. In one embodiment, the predetermined capacity may be a capacity of the AC unit measured upon installation or during an initial set-up process. Thus, the variation value may represent, for instance, how much the capacity of the AC unit has deteriorated from the day of installation of the AC unit. In another embodiment, the predetermined capacity may be lab tested data measured from a different AC unit. Thus, the variation value may represent how much the measured capacity of the AC unit varies from that of a representative AC unit tested under certain controlled conditions. In yet another embodiment, a table of values can be referenced to determine the predetermined capacity, wherein the table correlates measurements taken from an outdoor unit of the AC unit with a predetermined capacity value. For example, a controller may request a measurement of an outdoor ambient temperature from an outdoor temperature sensor and a compressor speed from the compressor. Upon receiving the outdoor ambient temperature and the compressor speed, these values can be compared to a table wherein a predetermined capacity value is associated with the two values. Thus, at a certain temperature range and in a certain compressor speed range, a single predetermined capacity value is expected. The selected predetermined capacity value or table of predetermined capacity values may be embedded in the AC unit. Following the determination of the predetermined capacity value, a variation value may be determined between the measured capacity value and the predetermined capacity value. The variation value may be a percent difference (e.g., percent error difference) between the two capacity values. In another embodiment, the variation value may simply be a value determined by subtracting to find the difference between the two measured capacities.

[0067] At 518, the method 500 includes determining a fault status based on the variation value. The variation value may be compared to a predetermined threshold value in order to determine if the variation value is above or below the threshold value. The fault status may contain two modes; fault detected, or no fault detected. For example, the threshold value may be a constant numerical value such that if the variation value is less than the threshold value, then no fault is detected. No fault being detected may represent that the measured capacity of the AC unit is not considered to be performing poorly or needing servicing. Thus, when no fault is detected the measured capacity of the AC unit may be considered efficient. In contrast, if the variation value is greater than the threshold value, then a fault is detected. A fault may represent that the measured capacity has deteriorated past an acceptable point and is considered to be performing poorly. In this case, the AC unit may need to be serviced.

[0068] At 520, the method 500 includes initiating a status indicator from the AC unit based on the fault status. Once the controller has determined if a fault has been detected or not, a status indicator may be initiated in order to communicate the fault status. The status indicator may be represented in one or more ways. For example, the status indicator may include or be provided as a message (e.g., containing text stating that either a fault has been detected, or no fault has been detected). The message may be sent to another device. In an additional or alternative example, the status indicator may include a code. The code may be a combination of numbers or letters. Optionally, a first code may represent no fault detected and a second code may represent a fault detected. In another additional or alternative example, the status indicator may comprise a graphic. A first graphic (e.g., a red warning symbol) may represent that a fault has been detected. No graphic or a second graphic (e.g., a green check) may represent that no fault has been detected. In yet another additional or alternative example, the status indicator may include or be provided as a light, wherein if the light is switched on, a fault is detected, but if the light is off, then no fault has been detected. In yet another additional or alternative example, the status indicator may directly output the measured capacity value. The measured capacity value may also be rounded up or down to a predetermined incremental value representative of the measured capacity value. The status indicator may also be communicated in a plurality of ways. For example, a controller may send the status indicator directly to a device of a provider. Thus, the provider is made aware of the possible fault before the customer is. In another example, the status indicator may be displayed on the AC unit (e.g., a digital display, user interface, panel, etc.). Thus, the customer may be made aware of the possible fault first.

[0069] 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 languages of the claims.

Claims

1. A method of capacity sensing in an AC unit, the method comprising:determining an airflow rate through the AC unit;determining a temperature difference between a pair of discrete points along an airflow path of the AC unit;determining a measured capacity value based on the temperature difference;determining a variation value between the measured capacity value and a predetermined capacity value;determining a fault status based on the variation value; andinitiating a status indicator from the AC unit based on the fault status.

2. The method of claim 1, wherein the temperature difference comprises the difference between an inlet air temperature and an outlet air temperature.

3. The method of claim 1, wherein the airflow rate comprises a mass flow rate determined by multiplying a volumetric flow rate of the AC unit by an air density value.

4. The method of claim 3, further comprising:determining the air density value prior to determining the measured capacity value, wherein the air density value is determined from a point temperature at a discrete first point of the pair of discrete points.

5. The method of claim 3, further comprising:determining the volumetric flow rate prior to determining the measured capacity value, wherein determining the volumetric flow rate comprises measuring a fan speed of a fan located in the AC unit.

6. The method of claim 1, wherein the fault status comprises two possible values, the two possible values comprising:a first value that depicts that a fault has been detected; anda second value that depicts that a fault is absent.

7. The method of claim 1, wherein the predetermined capacity value is embedded in the AC unit.

8. The method of claim 1, wherein the predetermined capacity value is based on an outdoor compressor speed and an outdoor ambient temperature.

9. The method of claim 1, further comprising:sending a message containing the status indicator.

10. An air conditioner (AC) unit, comprising:a housing unit;a sealed refrigerative system housed in the housing unit;an interior fan for providing airflow through the AC unit, the interior fan housed within the housing unit and in connection with the sealed refrigerative system to supply airflow across the sealed refrigerative system;a first thermistor positioned at a first discrete point of a pair of discrete points;a second thermistor positioned at a second discrete point of the pair of discrete points;a controller configured to direct a conditioning operation, the conditioning operation comprising:determining an airflow rate through the AC unit;determining a temperature difference between the pair of discrete points along an airflow path of the AC unit;determining a measured capacity value based on the temperature difference;determining a variation value between the measured capacity value and a predetermined capacity value;determining a fault status based on the variation value; andinitiating a status indicator from the AC unit based on the fault status.

11. The AC unit of claim 10, wherein the temperature difference comprises the difference between an inlet air temperature and an outlet air temperature.

12. The AC unit of claim 10, wherein the airflow rate comprises a mass flow rate determined by multiplying a volumetric flow rate of the AC unit by an air density value.

13. The AC unit of claim 12, further comprising:determining the air density value prior to determining the measured capacity value, wherein the air density value is determined from a point temperature at the first discrete point of the pair of discrete points.

14. The AC unit of claim 12, further comprising:determining the volumetric flow rate prior to determining the measured capacity value, wherein determining the volumetric flow rate comprises measuring a fan speed of a fan located in the AC unit.

15. The AC unit of claim 10, wherein the fault status comprises two possible values, the two possible values comprising:a first value that depicts that a fault has been detected; anda second value that depicts that a fault is absent.

16. The AC unit of claim 10, wherein the predetermined capacity value is embedded in the AC unit.

17. The AC unit of claim 10, wherein the predetermined capacity value is based on an outdoor compressor speed and an outdoor ambient temperature.

18. The AC unit of claim 10, further comprising:sending a message containing the status indicator.

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