HEAT PUMP SYSTEM REVERSING VALVE FAULT RECOVERY

FIELD OF THE INVENTION

[0001]The present subject matter relates generally to heat pump systems, and more particularly to systems and related methods for recovering from a reversing valve fault in a heat pump system.

BACKGROUND OF THE INVENTION

[0002]Heat pump systems and other air conditioner systems or air conditioning systems are conventionally utilized to adjust the temperature within structures such as dwellings and office buildings. A typical air conditioner or air conditioning system includes an indoor portion comprising one or more indoor units and an outdoor portion comprising at least one outdoor unit. Each of the indoor unit(s) and the outdoor unit(s) generally includes a heat exchanger by which thermal energy is transferred between refrigerant in a sealed system and air. The indoor portion generally communicates (e.g., exchanges air) with the area within a building, and the outdoor portion generally communicates (e.g., exchanges air) with the area outside a building. Generally, the indoor unit may include a fan operable to rotate to motivate air through the indoor unit, or each indoor unit (when the indoor portion includes multiple indoor units) may include such a fan. Another fan (or fans) may be operable to rotate to motivate air through the outdoor portion. The sealed system includes a compressor, and the sealed system is generally coupled to the indoor unit(s) and the outdoor unit(s) to treat (e.g., cool or heat) air as it is circulated through the units. One or more control boards are typically provided to direct the operation of various elements of the particular air conditioner system.

[0003]Some air conditioner systems include a reversing valve coupled in line with the sealed system, whereby the reversing valve selectively directs the flow of vapor refrigerant from the compressor to one or the other of the indoor heat exchanger (e.g., for a heating mode or heat pump mode in which the indoor heat exchanger acts as the condenser in the sealed system) or the outdoor heat exchanger (e.g., for a cooling mode in which the outdoor heat exchanger operates as the condenser in the sealed system). Such systems, e.g., which include a reversing valve, may be referred to as heat pump systems or heat pump units.

[0004]In some instances, the reversing valve may fail, e.g., get stuck, or otherwise not move to the selected position as expected. When this occurs, the system may provide heating when cooling is desired or provide cooling when heating is desired as a result of the reversing valve not operating as intended.

[0005]As a result, further improvements to heat pump systems may be advantageous. In particular, it would be useful to provide systems and methods for recovering from reversing valve faults, e.g., unsticking the reversing valve, in such systems.

BRIEF DESCRIPTION OF THE INVENTION

[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 operating a heat pump system is provided. The heat pump system includes an outdoor portion, an indoor portion, and a sealed system coupled between the outdoor portion and the indoor portion to circulate refrigerant through an indoor heat exchanger of the indoor portion and an outdoor heat exchanger of the outdoor portion. The sealed system includes a reversing valve to selectively reverse flow direction of the refrigerant. The method includes detecting a fault condition of the reversing valve and stopping a compressor of the sealed system in response to the detected fault condition of the reversing valve. The method also includes actuating the reversing valve from a first position to a second position and back to the first position after stopping the compressor and restarting the compressor after actuating the reversing valve.

[0008]In another exemplary aspect of the present disclosure, a heat pump system is provided. The heat pump system includes an outdoor portion, an indoor portion, and a sealed system coupled between the outdoor portion and the indoor portion to circulate refrigerant through an indoor heat exchanger of the indoor portion and an outdoor heat exchanger of the outdoor portion. The sealed system includes a reversing valve to selectively reverse flow direction of the refrigerant. The heat pump system also includes a controller. The controller is configured for detecting a fault condition of the reversing valve and stopping a compressor of the sealed system in response to the detected fault condition of the reversing valve. The controller is also configured for actuating the reversing valve from a first position to a second position and back to the first position after stopping the compressor and restarting the compressor after actuating the reversing valve.

[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 schematic illustration of a heat pump system according to one or more exemplary embodiments of the present disclosure.

[0012]FIG. 2 provides a flowchart illustrating an exemplary method of operating a heat pump system according to one or more additional exemplary embodiments of the present disclosure.

DETAILED DESCRIPTION

[0013]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.

[0014]As used herein, 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”). The terms “upstream” and “downstream” refer to the relative flow direction with respect to fluid flow in a fluid pathway. For example, “upstream” refers to the flow direction from which the fluid flows, and “downstream” refers to the flow direction to which the fluid flows.

[0015]As used herein, terms of approximation, such as “generally,” or “about” include values within ten percent greater or less than the stated value. 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. For example, “generally vertical” includes directions within ten degrees of vertical in any direction, e.g., clockwise or counterclockwise.

[0016]Turning now to the figures, FIG. 1 illustrates an exemplary heat pump system 100. The exemplary heat pump system 100 may be generally known as a split system or a multi-split system, e.g., the heat pump system 100 may include an outdoor portion 102, e.g., positioned outside of the structure to be cooled, and an indoor portion 104, e.g., positioned inside of the structure to be cooled. The outdoor portion 102 may include an outdoor unit 106, and the outdoor unit 106 may include an outdoor heat exchanger 108 and an outdoor fan 110. The indoor portion 104 may include at least one indoor unit 112, and the indoor unit 112 may include an indoor heat exchanger 114 and an indoor fan 116. In embodiments where multiple indoor units are provided, each indoor unit may be a substantial duplicate of every other indoor unit, e.g., each indoor unit may include a heat exchanger and a fan similar to those illustrated in FIG. 1. Accordingly, only a single indoor unit 112 is illustrated in FIG. 1 for the sake of clarity. The indoor unit 112 may be located in an enclosed space 180, such as a room, a mechanical closet, or other portion of the structure to be cooled.

[0017]Heat pump system 100 also includes a sealed system 130, e.g., generally comprising a series of conduits interlinking a compressor 118, the outdoor heat exchanger 108, the indoor heat exchanger 114 (as well as additional indoor heat exchangers of any other indoor units which may be provided), and other refrigerant flow components. Compressor 118 is operable to compress the refrigerant. Accordingly, the pressure and temperature of the refrigerant may be increased in compressor 118 such that the refrigerant becomes a more superheated vapor. The sealed system may be a thermodynamic assembly, which may be operated as a refrigeration assembly (and thus perform an air conditioning cycle or refrigeration cycle) or operated as a heat pump (and thus perform a heating cycle or heat pump cycle). Thus, as is understood, the exemplary heat pump system 100 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). The compressor 118 may be in fluid communication with the heat exchangers 108, 114 to flow refrigerant therethrough, as is generally understood. The outdoor and indoor heat exchangers 108, 114 may each include coils, through which the refrigerant may flow for heat exchange purposes, as is generally understood. Moreover, as may be seen in FIG. 1, heat exchangers 108, 114 may each include multiple circuits therethrough.

[0018]Operation of the heat pump system 100 in heating mode or cooling mode may be controlled or selected based on the position of a reversing valve 120, which may be, for example, a four-way valve. The reversing valve 120 selectively directs compressed refrigerant from compressor 118 to either indoor heat exchanger 114 or outdoor heat exchanger 108. The direction of refrigerant flow through the sealed system 130 in cooling mode is indicated by solid line arrows in FIG. 1, and the direction of refrigerant flow through the sealed system 130 in heating mode is indicated by dashed line arrows in FIG. 1. For example, in cooling mode, reversing valve 120 is arranged or configured to direct compressed, e.g., high-pressure, vapor refrigerant from compressor 118 to outdoor heat exchanger 108. Conversely, in heating mode, reversing valve 120 is arranged or configured to direct compressed, e.g., high-pressure, vapor refrigerant from compressor 118 to indoor heat exchanger 114. Thus, reversing valve 120 permits sealed system 130 to adjust between the heating mode and the cooling mode, as will be understood by those skilled in the art.

[0019]In cooling mode, the outdoor heat exchanger 108 acts as a condenser, e.g., outdoor heat exchanger 108 is operable to reject heat into the exterior atmosphere, when sealed system 130 is operating in the cooling mode. For example, the superheated vapor from compressor 118 may enter outdoor heat exchanger 108 from reversing valve 120. Within outdoor heat exchanger 108, the refrigerant transfers energy to the exterior atmosphere and condenses into a saturated liquid and/or liquid-vapor mixture. The exterior air handler or fan 110 positioned adjacent outdoor heat exchanger 108 may facilitate or urge a flow of air from the exterior atmosphere across outdoor heat exchanger 108 in order to facilitate heat transfer.

[0020]In cooling mode, indoor heat exchanger 114 acts as an evaporator. Thus, indoor heat exchanger 114 is operable to heat refrigerant within indoor heat exchanger 114 with energy from the indoor atmosphere when sealed system 130 is operating in the cooling mode. For example, the liquid or liquid-vapor mixture refrigerant may enter indoor heat exchanger 114. Within indoor heat exchanger 114, the refrigerant receives energy from the indoor atmosphere and vaporizes into superheated vapor and/or high quality vapor mixture. An indoor air handler or fan 116 positioned adjacent indoor heat exchanger 114 may facilitate or urge a flow of air from the indoor atmosphere across indoor heat exchanger 114 in order to facilitate heat transfer.

[0021]During operation of sealed system 130 in the heating mode, reversing valve 120 reverses the direction of refrigerant flow through sealed system 130. Thus, in the heating mode, indoor heat exchanger 114 is disposed downstream of compressor 118 and acts as a condenser, e.g., such that indoor heat exchanger 114 is operable to reject heat into the indoor atmosphere. In addition, outdoor heat exchanger 108 acts as an evaporator in the heating mode, e.g., such that outdoor heat exchanger 108 is operable to heat refrigerant within outdoor heat exchanger 108 with energy from the exterior atmosphere.

[0022]The heat pump system 100 may further include a gas service valve 122 and a liquid service valve 124. The heat pump system 100 may also include temperature sensors 166 at various locations throughout the system 100, e.g., to measure ambient temperatures, inlet temperatures, outlet temperatures, and/or temperatures of the heat exchanger coils, in various combinations based on the number and placement of the temperature sensors 166. The heat pump system 100 may further include an outdoor expansion valve 126 and a strainer 128. A high-pressure switch 140 may be provided on one side of the compressor 118 and a low-pressure switch 142 may be provided on the other side of the compressor 118. Furthermore, a capillary tube 144 and an oil separator 146 may be coupled to the compressor 118. The heat pump system 100 may further include an accumulator 150 configured to retain liquid-phase refrigerant therein and thus prevent liquid refrigerant flooding the compressor 118 (e.g., the liquid-phase refrigerant may accumulate within the accumulator 150 such that the liquid-phase refrigerant does not reach the compressor 118). A check valve 152 may be coupled to the accumulator 150 and may be positioned and configured to permit refrigerant flow to the accumulator 150 and prevent or limit refrigerant flow away from the accumulator 150.

[0023]An expansion device, e.g., electronic expansion valve 160, may be positioned indoors, e.g., in the indoor portion 104 of the heat pump system 100, downstream of the liquid service valve 124 and upstream of the indoor heat exchanger 114 when the heat pump system 100 is in cooling mode. When multiple indoor units 112 are provided, an expansion valve 160 may be provided for each indoor unit 114. The electronic expansion valve or valves 160 may generally expand the refrigerant, lowering the pressure and temperature thereof. The refrigerant may then be flowed through indoor heat exchanger 114. Additionally, the electronic expansion valve(s) 160 may be actuated, such as by a stepper motor, to selectively increase or reduce the flow rate of refrigerant therethrough. A strainer 162 may be provided between the electronic expansion valve 160 and the indoor heat exchanger 114.

[0024]As mentioned, the heat pump system 100 may be a multi-split system having one or more indoor units 112 in addition to the one illustrated example indoor unit 112. Refrigerant branches 164 extending to and from such additional indoor units are partially illustrated in FIG. 1 by way of example.

[0025]The operation of heat pump 100 including compressor 118 (and thus the sealed system 130 generally), indoor fan 116, outdoor fan 110, and other suitable components may be controlled by a control board or controller 158. Controller 158 may be in communication (via, for example, a suitable wired or wireless connection) with such components of the heat pump 100. Controller 158 may also be in communication with various sensors, e.g., temperature sensors 166, in the heat pump system 100. By way of example, the controller 158 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 heat pump system 100. 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. 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. Alternatively, controller 158 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 gates, and the like) to perform control functionality instead of relying upon software. Further, it should be understood that controllers 158 as disclosed herein are capable of and may be operable to perform any methods and associated method steps as disclosed herein.

[0026]It should be understood that the illustrated heat pump system 100 is generally referred to as a split system, and this configuration is provided by way of example only. The benefits of the present disclosure apply to other types and styles of heat pump systems as well. As one example, the heat pump system may also be provided as a one-unit type system, such as a single-package vertical unit (SPVU) or a package terminal air conditioner (PTAC), or any other suitable one-unit type air conditioner appliance, e.g., not limited to a SPVU or PTAC. As used herein, a “one-unit” type system generally includes a package housing that supports both an indoor portion and an outdoor portion within an interior of the single housing. Consequently, the description set forth herein is for illustrative purposes only and is not intended to be limiting in any aspect to a particular heat pump system configuration. For example, the indoor portion and the outdoor portion may be portions of a single unit, e.g., may be provided in a single housing, or may include separate units, such as in the illustrated split system, among other possible variations within the scope of the present disclosure.

[0027]Turning now to FIG. 2, embodiments of the present disclosure may also include methods of operating a heat pump system, such as the example method 700 illustrated in FIG. 2. Such methods may be used with any suitable heat pump system, such as heat pump system 100 as described above, or any other heat pump system, e.g., any air conditioning unit or system, Heating Ventilation and Air Conditioning (HVAC) system, etc., which includes indoor and outdoor portions and a reversing valve such that the unit or system is operable in both cooling mode and heating mode in response to the position of the reversing valve.

[0028]For example, as mentioned above, the heat pump system 100 may include a controller 158 and the controller 158 may be operable for, e.g., configured for, performing some or all of the methods and/or steps thereof described herein. For example, one or more method steps may be embodied as an algorithm or program stored in a memory of the controller 158 and executed by the controller 158 in response to a user input.

[0029]As illustrated in FIG. 2, method 700 may include (710) detecting a fault condition of the reversing valve. In general, the fault condition of the reversing valve is detected when the reversing valve is not in the expected or desired position, such that refrigerant is flowing through the sealed system of the heat pump system in the opposite direction from the intended direction, causing the heat pump system to operate undesirably, e.g., heating when in cooling mode or cooling when in heating mode. In some embodiments, the reversing valve fault condition may be detected indirectly, e.g., without direct positional feedback (or other direct feedback) from the reversing valve or a sensor directly coupled thereto, using measurements from one or more sensors in the heat pump system such as temperature sensors and/or refrigerant pressure sensors. For example, a plurality of measurements from a plurality of sensors (e.g., temperature and/or refrigerant pressure sensors) may be obtained, and the status of the reversing valve may be checked by comparing sets (e.g., pairs) of the measurements to determine whether the system is operating in heating mode or cooling mode, which may be checked against the call for heating or cooling to detect a fault condition of the reversing valve. A plurality of such status checks may be performed, and each status check may include comparing a respective set of measurements of a plurality of measurements obtained from a plurality of sensors in the heat pump system. The fault condition of the reversing valve may also be, for example, the reversing valve is stuck, is damaged (such as wiring to actuate the reversing valve may be damaged), a relay between the controller and the reversing valve may be broken, and/or other reversing valve faults may be present which result in operating the heat pump system in the wrong mode (heating when it should be cooling or vice versa).

[0030]Further, it is to be understood that methods according to the present subject matter include operating the heat pump system and are performed, e.g., reversing valve fault condition is detected, while the heat pump system is operating. For example, detecting the fault condition of the reversing valve may include determining whether the heat pump system is in a heating mode or a cooling mode, and the fault condition may be determined when the heat pump system is providing cooling when in the heating mode or is providing heating when in the cooling mode. Thus, detecting the fault condition of the reversing valve is to be understood as checking that the heat pump system is operating as intended, e.g., in heating mode when heating is called for or in cooling mode when cooling is called for. The call for heating or cooling may come from a thermostat of the heat pump system, e.g., which measures a current ambient temperature within the conditioned space and compares the current ambient temperature within the conditioned space to a target temperature or range of target temperatures. When the current ambient temperature within the conditioned space is greater than the target temperature or above the upper limit of the target temperature range, the thermostat calls for cooling, and when the current ambient temperature within the conditioned space is less than the target temperature or below the lower limit of the target temperature range, the thermostat calls for heating. The call for heating or cooling may also or instead come from a user interface or user input, e.g., which receives a selection from a user for cooling mode or heating mode.

[0031]When there is a call for heating or cooling, the heat pump system may activate, e.g., by moving the reversing valve to the appropriate position for the selected mode (or at least attempting to do so) and starting the compressor to begin the flow of refrigerant through the sealed system. In some embodiments, exemplary methods such as method 700 may further include (720) stopping the compressor of the sealed system in response to the detected fault condition of the reversing valve.

[0032]Also as may be seen in FIG. 2, method 700 may further include actuating the reversing valve back and forth, such as actuating the reversing valve from a first position to a second position and back to the first position after stopping the compressor as indicated at (730) in FIG. 2. The reversing valve may be actuated back and forth one or more times. For example, some embodiments may include actuating the reversing valve to the second position after actuating the reversing valve back to the first position and before restarting the compressor.

[0033]Actuating the reversing valve back and forth, e.g., from the first position to the second position and back to the first position, after stopping the compressor may promote recovery from the reversing valve fault condition, such as may loosen the reversing valve or work the reversing valve free when the reversing valve is stuck. The reversing valve may be actuated back and forth multiple times to attempt to recover from the reversing valve fault condition. If the reversing valve is not able to recover from the fault condition after actuating back and forth one or more times, an alert or notification may be sent to a user of the heat pump system. Accordingly, it should be understood that “actuating” the reversing valve in this context means commanding the reversing valve to change position and/or operating a mechanism, e.g., actuator, which is coupled to the reversing valve and is configured to move the reversing valve, although in at least some instances the reversing valve may not actually move when actuated, or may move only part of the way between the first position and the second position (e.g., as noted herein throughout, the reversing valve may be in a fault condition) when actuated.

[0034]The heat pump system may also include a user interface, such as a display and one or more user input devices. In some embodiments, the user interface, e.g., the display thereof, may be configured for, and exemplary methods may include, providing a user notification in response to the reversing valve fault condition persisting after one or more recovery attempts. The user notification may be or may include a visual notification, e.g., on the display, an audible notification, e.g., a beep, chime, or other alert sound, or combinations of audible and visual notifications. The user notification may be provided locally, e.g., on a user interface of the heat pump system 100 that is onboard the heat pump system, e.g., directly physically integrated into the heat pump system, and/or may be provided remotely, e.g., on a remote user interface such as a computer (e.g., personal computer or tablet computer), smartphone, or other similar device which is spaced apart from the heat pump system 100 and in wireless communication with the heat pump system 100, e.g., with the controller 158 thereof. The heat pump system may also or instead be deactivated when the reversing valve is not able to recover from the fault condition, and/or the mode (heating or cooling) which is affected by the fault condition may be disabled when the reversing valve is not able to recover from the fault condition. For example, the fault condition may be detected while operating the heat pump system in one of the heating mode or the cooling mode, and exemplary methods according to the present disclosure may include disabling the one of the heating mode or the cooling mode, e.g., disabling the mode during which the fault condition was detected.

[0035]As illustrated in FIG. 2, method 700 may further include restarting the compressor after actuating the reversing valve. As mentioned, actuating the reversing valve back and forth (730) may be performed one or more times, such as one or more times before restarting the compressor at (740). Additionally, the method 700 may be recursive, e.g., exemplary methods according to the present subject matter may include further reversing valve status checks after restarting the compressor, and when the fault condition is detected again, additional attempts to recover, e.g., further iterations of (720) and (730), may be performed.

[0036]For example, in some embodiments, methods according to the present subject matter may include detecting a second fault condition of the reversing valve after restarting the compressor, stopping the compressor in response to the detected second fault condition of the reversing valve, and actuating the reversing valve back and forth one or more times after stopping the compressor in response to the detected second fault condition of the reversing valve. Such embodiments may further include restarting the compressor after actuating the reversing valve from the first position to the second position and back to the first position one or more times. Continuing the example, in some instances a third fault condition may be detected after restarting the compressor again. In such cases, exemplary methods may include providing a reversing valve fault user notification in response to the third fault condition of the reversing valve.

[0037]Actuating the reversing valve back and forth may include energizing and deenergizing an actuator of the reversing valve. For example, the reversing valve may be a solenoid valve, e.g., the reversing valve may include a solenoid. In such embodiments, actuating the reversing valve from the first position to the second position and back to the first position may include energizing and deenergizing the solenoid, e.g., energizing and deenergizing the solenoid at least once.

[0038]Some embodiments may also include waiting for refrigerant pressures in the outdoor heat exchange and the indoor heat exchanger to equalize after stopping the compressor and before actuating the reversing valve. Actuating (e.g., attempting to move, as discussed herein) the reversing valve may be more effective, e.g., the reversing valve may move more easily, when the refrigerant pressures have stabilized and/or equalized.

[0039]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.