Refrigeration cycle device and control method

Abstract

Provided is a refrigeration cycle device that includes a first device comprising a compressor, and a second device comprising a heat exchanger. The refrigeration cycle device comprises: a liquid shut-off valve provided to a liquid pipe that connects the first device and the second device; a gas shut-off valve provided to a gas pipe that connects the first device and the second device; and a control device. When the compressor is stopped, the control device sets the liquid shut-off valve to a closed state, sets the gas shut-off valve to an open state, operates the compressor in a first cycle in which the liquid shut-off valve is upstream of the heat exchanger, and evaluates the shut-off performance of the liquid shut-off valve. When the compressor is stopped, the control device sets the liquid shut-off valve to an open state, sets the gas shut-off valve to a closed state, operates the compressor in a second cycle in which the gas shut-off valve is upstream of the heat exchanger, and evaluates the shut-off performance of the gas shut-off valve.

Description

Refrigeration cycle device and control method

[0001] The present invention relates to a refrigeration cycle device, and more particularly to a refrigeration cycle device and a control method thereof.

[0002] 2. Description of the Related Art In air conditioners, shutoff valves are sometimes provided in liquid piping and gas piping connecting the outdoor unit and the indoor unit in order to reduce the amount of refrigerant leakage when it occurs.

[0003] In relation to the above-mentioned shutoff valves for liquid piping and gas piping, Japanese Patent Laid-Open Publication No. 2017-9267 (Patent Document 1, Japanese Patent No. 6604051) is known.

[0004] Patent Document 1 discloses an air conditioning system that is equipped with shutoff valves that close when a refrigerant leak is detected in a liquid refrigerant pipe and a gas refrigerant pipe, and that aims to reliably check the operation, including the shutoff performance, of the shutoff valves. In the conventional technology of Patent Document 1, the air conditioning system performs a shutoff valve inspection process to check the operation of the liquid-side shutoff valve and the gas-side shutoff valve by operating the compressor in a cooling cycle and opening and closing the liquid-side shutoff valve and the gas-side shutoff valve, and determining whether the liquid-side shutoff valve and the gas-side shutoff valve are operating normally based on temperature values ​​detected by a temperature sensor provided in the indoor unit.

[0005] The prior art of Patent Document 1 determines whether the liquid-side shutoff valve and the gas-side shutoff valve are operating normally during the cooling cycle. This requires the downstream gas shutoff valve to be closed and then opened, raising concerns about reliability in terms of the risk of liquid pooling in the indoor heat exchanger and liquid backflow to the compressor suction side. Furthermore, in this prior art, the operation of the downstream gas shutoff valve is determined by detecting the temperature change caused by the flow of accumulated refrigerant when both the liquid and gas shutoff valves are closed and only the downstream gas shutoff valve is opened. This makes it difficult to determine if the amount of accumulated refrigerant is small, and conversely, if the amount of refrigerant is large, liquid backflow may occur. This is insufficient from this perspective.

[0006] Japanese Patent Application Laid-Open No. 2017-9267

[0007] The present disclosure has been made in consideration of the above points, and aims to provide a refrigeration cycle device and a control method thereof that can more reliably confirm the shut-off performance of the liquid shut-off valve and the gas shut-off valve while preventing a deterioration in reliability due to liquid return.

[0008] In view of the above, the present disclosure provides a refrigeration cycle apparatus having the following characteristics: the refrigeration cycle apparatus includes a first unit having a compressor and a second unit having a heat exchanger. The refrigeration cycle apparatus includes a liquid shutoff valve provided in a liquid pipe connecting the first unit and the second unit, and a gas shutoff valve provided in a gas pipe connecting the first unit and the second unit. The refrigeration cycle apparatus further includes a control device that, when the compressor is stopped, closes the liquid shutoff valve and opens the gas shutoff valve, and operates the compressor in a first cycle in which the liquid shutoff valve is upstream of the heat exchanger, thereby evaluating the shutoff performance of the liquid shutoff valve. The control device also, when the compressor is stopped, opens the liquid shutoff valve, closes the gas shutoff valve, and operates the compressor in a second cycle in which the gas shutoff valve is upstream of the heat exchanger, thereby evaluating the shutoff performance of the gas shutoff valve.

[0009] The present disclosure further discloses a control method executed by a control device of a refrigeration cycle apparatus including a first device having a compressor and a second device having a heat exchanger, the control method having the following characteristics. The control method includes a step in which the control device closes a liquid shutoff valve provided in a liquid pipe connecting the second device and the first device and opens a gas shutoff valve provided in a gas pipe connecting the second device and the first device when the compressor is stopped. The control method also includes a step in which the control device operates the compressor in a first cycle in which the liquid shutoff valve is upstream of the heat exchanger, and evaluates the shutoff performance of the liquid shutoff valve. The control method further includes a step in which the control device opens the liquid shutoff valve and closes the gas shutoff valve when the compressor is stopped. The control method also includes a step in which the control device operates the compressor in a second cycle in which the gas shutoff valve is upstream of the heat exchanger, and evaluates the shutoff performance of the gas shutoff valve.

[0010] With the above configuration, it is possible to more reliably check the shutoff performance of both the liquid shutoff valve and the gas shutoff valve while preventing deterioration of reliability due to liquid return.

[0011] Fig. 1 is a diagram showing an example of the configuration of an air conditioner according to an embodiment of the present disclosure; Fig. 2 is a flowchart explaining the shutoff valve inspection operation performed by a control device in an air conditioner according to an embodiment of the present disclosure; Fig. 3 is a diagram explaining the refrigerant flow and the valve open / close state during the cooling and heating cycles of the shutoff valve inspection operation in an air conditioner according to an embodiment of the present disclosure; Fig. 4 is a flowchart explaining the shutoff valve inspection operation performed by a control device in an air conditioner according to another embodiment of the present disclosure; Fig. 5 is a diagram explaining the refrigerant flow and the valve open / close state during the cooling and heating cycles of the shutoff valve inspection operation in an air conditioner according to another embodiment of the present disclosure.

[0012] One or more embodiments of the present disclosure will be described below with reference to the drawings, but the embodiments of the present disclosure are not limited to the specific embodiments described below. Note that the same reference numerals throughout the drawings indicate the same or corresponding parts.

[0013] The present disclosure is directed to a refrigeration cycle apparatus such as an air conditioner 100. The refrigeration cycle apparatus (air conditioner 100) according to an embodiment of the present disclosure includes a first unit (outdoor unit 10) having a compressor (11), and a second unit (indoor unit 40) having a heat exchanger (41). The refrigeration cycle apparatus (100) further includes a liquid shutoff valve (50) provided in a liquid pipe (31) connecting the first unit (10) and the second unit (40), and a gas shutoff valve (51) provided in a gas pipe (30) connecting the first unit (10) and the second unit (40). The refrigeration cycle device (100) also includes a control device (26), which, when the compressor (11) is stopped, closes the liquid shutoff valve (50), opens the gas shutoff valve (51), and operates the compressor (11) in a first cycle (cooling cycle) in which the liquid shutoff valve (50) is upstream of the heat exchanger (41) to evaluate the shutoff performance of the liquid shutoff valve (50). The control device (26) also, when the compressor (11) is stopped, opens the liquid shutoff valve (50), closes the gas shutoff valve (51), and operates the compressor (11) in a second cycle (heating cycle) in which the gas shutoff valve (51) is upstream of the heat exchanger (41) to evaluate the shutoff performance of the gas shutoff valve (51).

[0014] In the above configuration, in the first cycle (cooling cycle) and the second cycle (heating cycle), the shutoff performance is evaluated with the upstream shutoff valves (50 and 51) closed. This prevents refrigerant from accumulating in the heat exchanger (41), thereby reducing the risk of liquid backflow when the valves are reopened. This allows for highly reliable determination regardless of the refrigerant accumulation state. This makes it possible to more reliably check the shutoff performance of both the liquid shutoff valve (50) and the gas shutoff valve (51) while preventing deterioration in reliability due to liquid backflow.

[0015] In a preferred embodiment, the refrigeration cycle apparatus (100) is an air conditioner, the first apparatus (10) is an outdoor unit, and the second apparatus (40) includes a plurality of indoor units (40a-40b). The liquid shutoff valve (50) includes a plurality of liquid shutoff valves (50a-50b) corresponding to the plurality of indoor units (40a-40b), and the gas shutoff valve (51) includes a plurality of gas shutoff valves (51a-51b) corresponding to the plurality of indoor units (40a-40b). In such an embodiment, the control device (26) operates the plurality of indoor units (40a-40b) together in the shutoff valve inspection operation, and is able to evaluate the shutoff performance of the plurality of liquid shutoff valves (50a-50b) in a single cooling cycle and evaluate the shutoff performance of the plurality of gas shutoff valves (51a-51b) in a single heating cycle. This allows the shutoff performance of the shutoff valves of multiple indoor units (40a to 40b) equipped with shutoff valves to be inspected simultaneously, thereby shortening the inspection time.

[0016] In a specific embodiment, the refrigeration cycle apparatus (100) further includes one or more other indoor units (40c) connected to the outdoor unit (10), with one or more liquid pipes and one or more gas pipes between the one or more other indoor units (40c) and the outdoor unit (10) being assumed to be not provided with shutoff valves. The control device (26) controls the one or more other indoor units (40c) to maintain them in a stopped state during the shutoff valve inspection operation. In this way, by operating only the indoor units provided with shutoff valves, refrigerant circulation to the other indoor units not connected to shutoff valves can be suppressed, and the impact of installation method on the judgment can be reduced.

[0017] In a particular embodiment, the second device (40) has a temperature sensor (44), and the control device (26) can determine the shut-off performance of the liquid shut-off valve (50) and the shut-off performance of the gas shut-off valve (51) based on the value of the temperature sensor (44) of the second device (40).

[0018] In another specific embodiment, the refrigeration cycle device (100) includes first and second temperature sensors provided before and after the liquid shutoff valve (50), and third and fourth temperature sensors provided before and after the gas shutoff valve (51). The control device (26) determines the shutoff performance of the liquid shutoff valve (50) based on the values ​​of the first and second temperature sensors, and determines the shutoff performance of the gas shutoff valve (51) based on the values ​​of the third and fourth temperature sensors.

[0019] In a specific embodiment, the control device (26) is characterized in that, before starting the compressor (11), it performs air blowing operation, closes (or opens) the liquid shutoff valve (50), opens (or closes) the gas shutoff valve (51), starts the compressor (11), evaluates the shutoff performance of the liquid shutoff valve (50) (or the gas shutoff valve (51)), stops the compressor (11), opens (or closes) the liquid shutoff valve (50), closes (or opens) the gas shutoff valve (51), starts the compressor (11), and evaluates the shutoff performance of the gas shutoff valve (51) (or the liquid shutoff valve (51)).

[0020] In a specific embodiment, the liquid piping includes piping from the liquid end (17) of the first device (10) to the liquid end of the heat exchanger (41), including the liquid connection piping (31) connecting the second device (40) and the first device (10). The gas piping includes piping from the gas end (16) of the first device (10) to the gas end of the heat exchanger (41), including the gas connection piping (30) connecting the second device (40) and the first device (10).

[0021] In a specific embodiment, the liquid shutoff valve (50) and the gas shutoff valve (51) are valves that are provided on any of the above-mentioned liquid piping and gas piping paths, and shut off the refrigeration cycle circuit by closing in response to leakage of refrigerant from the refrigeration cycle circuit, thereby limiting the amount of refrigerant leaking from the piping of the refrigeration cycle device (10) to the external space.

[0022] A control method executed by a control device (26) of a refrigeration cycle apparatus (100) according to an embodiment of the present disclosure is provided. The control method includes the steps of, when a compressor (11) is stopped, the control device (26) closing a liquid shutoff valve (50) provided in a liquid pipe (31) connecting a first device (outdoor unit 10) and a second device (indoor unit 40) and opening a gas shutoff valve (51) provided in a gas pipe (30) connecting the first device (10) and the second device (40). The control method further includes the step of the control device (26) operating the compressor (11) in a first cycle (cooling cycle) in which the liquid shutoff valve (50) is upstream of a heat exchanger (41) to evaluate the shutoff performance of the liquid shutoff valve (50). The control method also includes a step in which the control device (26) opens the liquid shutoff valve (50) and closes the gas shutoff valve (51) when the compressor (11) is stopped, and a step in which the control device (26) operates the compressor (11) in a second cycle (heating cycle) in which the gas shutoff valve (51) is upstream of the heat exchanger (41) to evaluate the shutoff performance of the gas shutoff valve (51).

[0023] With the above-described configuration, it becomes possible to more reliably check the shutoff performance of both the liquid shutoff valve (50) and the gas shutoff valve (51) while preventing deterioration of reliability due to liquid return.

[0024] In a preferred embodiment, the refrigeration cycle apparatus is an air conditioner, the first apparatus (10) is an outdoor unit, and the second apparatus (40) includes a plurality of indoor units (40a-40b). The liquid shutoff valve (50) includes a plurality of liquid shutoff valves (50a-50b) corresponding to the plurality of indoor units (40a-40b), and the gas shutoff valve (51) includes a plurality of gas shutoff valves (51a-51b) corresponding to the plurality of indoor units (40a-40b). In this embodiment, the control device (26) includes, in the shutoff valve inspection operation, a step of operating the plurality of indoor units (40a-40b) together, a step of simultaneously evaluating the shutoff performance of the plurality of liquid shutoff valves (50a-50b) in the cooling cycle, and a step of simultaneously evaluating the shutoff performance of the plurality of gas shutoff valves (51a-51b) in the heating cycle. This allows the shutoff performance of the shutoff valves of multiple indoor units (40a to 40b) equipped with shutoff valves to be inspected simultaneously, thereby shortening the inspection time.

[0025] In a specific embodiment, the control method includes the steps of receiving an instruction to start an inspection operation, performing a fan operation before starting the compressor, and closing (or opening) the liquid shutoff valve (50) and opening (or closing) the gas shutoff valve (51), and then starting the compressor (11). The control method further includes the steps of evaluating the shutoff performance of the liquid shutoff valve (50) (or the gas shutoff valve (51)) and then stopping the compressor (11), opening (or closing) the liquid shutoff valve (50) and closing (or opening) the gas shutoff valve (51), and then starting the compressor (11), and evaluating the shutoff performance of the gas shutoff valve (51) (or the liquid shutoff valve (50)).

[0026] Below, with reference to Figures 1 to 3, an example of a refrigeration cycle device and a control method thereof according to one or more embodiments of the present disclosure will be described, taking as an example an air conditioner 100 including an outdoor unit 10 and multiple indoor units 40 and a control flow executed by its control device 26.

[0027] 1 is a diagram showing an example configuration of an air conditioner 100 according to an embodiment of the present disclosure. The air conditioner 100 is configured to include an outdoor unit 10 installed outdoors in a house, building, or the like, and multiple indoor units 40 installed indoors. In addition, the air conditioner 100 may also include an operation device (remote controller) in the room where the indoor units 40 are installed, for operating the indoor units 40 by wirelessly communicating with the indoor units 40.

[0028] The outdoor unit 10 and each indoor unit 40 are connected by two connecting pipes 30, 31 through which a refrigerant circulates as a heat medium. The connecting pipe 30 is a gas connecting pipe 30 through which a gas refrigerant flows, and the connecting pipe 31 is a liquid connecting pipe 31 through which a liquid refrigerant flows. For example, a hydrofluorocarbon such as R410A or R32 is used as the refrigerant.

[0029] The outdoor unit 10 and the indoor unit 40 are connected by a communication line to communicate with each other. Note that the outdoor unit 10 and the indoor unit 40 are not limited to being connected by a wired communication line, and may be connected wirelessly.

[0030] During operation, the indoor unit 40 takes in indoor air, exchanges heat between the taken-in air and a refrigerant supplied from the outdoor unit 10, and blows out cooled or heated air to cool or heat the room to a set temperature. To this end, the indoor unit 40 is equipped with an indoor heat exchanger 41 that exchanges heat between the indoor air and the refrigerant, and a blower (fan) 43 that takes in indoor air into the indoor heat exchanger 41 and blows out the air that has undergone heat exchange by the indoor heat exchanger 41. The indoor unit 40 also includes an indoor expansion valve 42 that expands the refrigerant and adjusts the flow rate of the refrigerant flowing through the indoor heat exchanger 41. The indoor unit 40 is further equipped with a temperature sensor 44 that detects the intake air temperature (room temperature), the discharge air temperature, the piping temperature, etc., in order to notify the outdoor unit 10 of the room temperature.

[0031] When operating in the cooling cycle, the indoor heat exchanger 41 functions as an evaporator, and refrigerant in a two-phase flow state consisting of a mixture of liquid and gas flows into the indoor heat exchanger 41. The liquid component of the refrigerant evaporates as it exchanges heat with air taken in by the fan 43 in the indoor heat exchanger 41, and the refrigerant is discharged from the indoor heat exchanger 41 as gas refrigerant and sent to the outdoor unit 10. The liquid component evaporates at a certain temperature (saturation temperature) corresponding to the pressure inside the indoor heat exchanger 41, and is discharged from the indoor heat exchanger 41 at or above the saturation temperature. The flow of refrigerant in the cooling cycle is indicated by solid arrows.

[0032] In the heating cycle, the indoor heat exchanger 41 functions as a condenser, and refrigerant gas flows into the indoor heat exchanger 41 from the outdoor unit 10 via the gas connection pipe 30. The refrigerant exchanges heat with air taken in by the fan 43 inside the indoor heat exchanger 41, becomes liquid refrigerant, and is sent to the outdoor unit 10 via the liquid connection pipe 31. The flow of refrigerant in the heating cycle is opposite to the flow in the cooling cycle, as indicated by the solid arrows.

[0033] Although FIG. 1 shows three indoor units 40a to 40c as the multiple indoor units 40, the number of indoor units 40 is not particularly limited and may be two, four or more. The multiple indoor units 40 may be installed in the same room, or all of the multiple indoor units 40 may be installed in different rooms, or one or more of the multiple indoor units 40 may be arranged in any combination in each of the multiple rooms. Hereinafter, when referring to a specific indoor unit, it will be referred to as "indoor unit 40a," for example, and when referring to any indoor unit or all indoor units collectively, it will be referred to as "indoor unit 40." The same applies to the internal configuration of the indoor units.

[0034] The outdoor unit 10 starts up upon receiving instructions from the control device 26 and begins operation in an operation mode set by a remote control or the like. The operation modes include cooling mode, heating mode, and fan mode. The outdoor unit 10 controls the temperature, pressure, flow rate, etc. of the refrigerant according to the set temperature, indoor temperature, pipe temperature, etc. The outdoor unit 10 also stops operation upon receiving a command from the control device 26. Note that although one outdoor unit 10 is shown in FIG. 1 , this does not preclude a configuration in which multiple outdoor units are installed.

[0035] The outdoor unit 10 is provided with a gas stop valve 16 and a liquid stop valve 17, and the gas stop valve 16 and the liquid stop valve 17 are connected to a gas communication pipe 30 and a liquid communication pipe 31, respectively. The outdoor unit 10 is connected to a plurality of indoor units 40 (indoor units 40a to 40c in FIG. 1 ) via the gas communication pipe 30 and the liquid communication pipe 31, and circulates a refrigerant.

[0036] The outdoor unit 10 is equipped with a compressor 11 for circulating a refrigerant. In the cooling cycle, the refrigerant gas compressed by the compressor 11 exchanges heat with air taken in by a fan 15 in an outdoor heat exchanger 13, and becomes liquid refrigerant. The liquid refrigerant is sent to the indoor unit 40 via a liquid connection pipe 31. The gas refrigerant from the indoor unit 40 flows into the outdoor unit 10 via a gas connection pipe 30 and is returned to the compressor 11.

[0037] The outdoor unit 10 is also equipped with a four-way valve 12 for reversing the direction of refrigerant flow to enable heating operation. In the heating cycle, the four-way valve 12 has a different path than that shown in Fig. 1, and the refrigerant gas compressed by the compressor 11 is sent to the indoor unit 40 via the gas connection pipe 30. Liquid refrigerant from the indoor unit 40 flows into the outdoor unit 10 via the liquid connection pipe 31, evaporates through heat exchange with air taken in by the fan 15 in the outdoor heat exchanger 13, is discharged as gas refrigerant from the indoor heat exchanger 41, and is returned to the compressor 11. The outdoor expansion valve 14 is provided to convert the high-pressure refrigerant into low-temperature, low-pressure refrigerant in the heating cycle and to adjust the refrigerant flow rate.

[0038] 1 , the outdoor unit 10 may further include a subcooling mainstream pipe 21 and a subcooling heat exchanger 20 that subcools the refrigerant passing through the subcooling mainstream pipe 21. The outdoor unit 10 is provided with a subcooling expansion valve 23, and some of the refrigerant passes through a subcooling side flow pipe 22, is decompressed by the subcooling expansion valve 23, enters the subcooling heat exchanger 20, where it exchanges heat with the refrigerant from the subcooling mainstream pipe 21 and evaporates, and is then returned to the compressor 11.

[0039] The flow rate of the refrigerant can be changed by changing the operating frequency of the compressor 11. Increasing the operating frequency of the compressor 11 increases the amount of refrigerant supplied, thereby increasing the air conditioning capacity. Conversely, decreasing the operating frequency of the compressor 11 decreases the amount of refrigerant supplied, thereby decreasing the air conditioning capacity.

[0040] The outdoor unit 10 is equipped with a control device 26. The outdoor unit 10 is equipped with a high-pressure side pressure sensor 60 on the discharge side of the compressor 11 and a low-pressure side pressure sensor 61 on the suction side. The outdoor unit 10 may also be equipped with a high-pressure-low-pressure bypass circuit 62 and a high-low-pressure bypass solenoid valve 63. These elements 62, 63 may be used to suppress high-pressure pressure increases and low-pressure pressure decreases during inspection operations, which will be described later. The control device 26 receives inputs of various temperatures detected by temperature sensors 44a to 44c of the indoor units 40a to 40c, various pressures detected by pressure sensors 60, 61, and other set temperatures and piping temperatures. Based on this input information and the operating mode, the control device 26 controls the operating frequency of the compressor 11 and the opening degree of the outdoor expansion valve 14. The control device 26 also switches the four-way valve 12 depending on the set operating mode.

[0041] In the above-described refrigeration cycle circuit, a plurality of liquid shutoff valves 50a to 50c are provided in the liquid piping path between the plurality of indoor units 40 and the outdoor unit 10, corresponding to the plurality of indoor units 40a to 40c. Furthermore, a plurality of gas shutoff valves 51a to 51c are provided in the gas piping path between the plurality of indoor units 40 and the outdoor unit 10, corresponding to the plurality of indoor units 40. Here, the liquid piping refers to the section including the piping from the liquid side end (liquid check valve 17) of the outdoor unit 10 to the liquid side end of the indoor heat exchanger 41, including the liquid connection piping 31 connecting each indoor unit 40 and the outdoor unit 10. The gas piping refers to the section including the piping from the gas side end (gas check valve 16) of the outdoor unit 10 to the gas side end of the indoor heat exchanger 41, including the gas connection piping 30 connecting each indoor unit 40 and the outdoor unit 10.

[0042] The liquid shutoff valve 50 and the gas shutoff valve 51 are valves that shut off the refrigeration cycle circuit by closing in response to a refrigerant leak in the refrigeration cycle circuit, thereby limiting the amount of refrigerant leaking from the indoor unit 40 or piping into the exterior space. Guidelines (JRA GL-16) established by the Japan Refrigeration and Air Conditioning Industry Association and others require that a detection alarm and a shutoff valve or mechanical ventilation device be installed as safety devices for the indoor unit. By operating the gas shutoff valve 51 and the liquid shutoff valve 50 in response to leak detection, the amount of refrigerant leaking into the exterior space can be reduced.

[0043] Furthermore, when using a slightly flammable refrigerant such as R32, the above-mentioned guidelines may require that the above-mentioned safety devices be confirmed to be operating normally a specified number of times within a specified period (e.g., once a year) for the gas shut-off valve 51 and the liquid shut-off valve 50.

[0044] Therefore, in an embodiment of the present disclosure, the control device 26 is configured to perform a shut-off valve inspection operation in response to an instruction from an operator, etc., to confirm that the gas shut-off valve 51 and the liquid shut-off valve 50 are operating normally. In the shut-off valve inspection operation, the control device 26 closes the liquid shut-off valve 50 and opens the gas shut-off valve 51 when the compressor 11 is stopped, and then operates the compressor 11 in a cooling cycle to evaluate the shut-off performance of the liquid shut-off valve 50. Furthermore, in the shut-off valve inspection operation, the control device 26 opens the liquid shut-off valve 50 and closes the gas shut-off valve 51 when the compressor 11 is stopped, and then operates the compressor 11 in a heating cycle to evaluate the shut-off performance of the gas shut-off valve 51.

[0045] In an embodiment of the present disclosure, in the cooling cycle and the heating cycle, the shutoff performance is evaluated with the upstream shutoff valve (liquid shutoff valve 50 in the cooling cycle and gas shutoff valve 51 in the heating cycle) in a closed state. This prevents refrigerant from accumulating in the indoor heat exchanger 41, thereby reducing the risk of liquid backflow when the valve is reopened. This allows for a highly reliable determination regardless of the refrigerant accumulation state. This makes it possible to more reliably confirm the shutoff performance of both the liquid shutoff valve 50 and the gas shutoff valve 51 while preventing deterioration in reliability due to liquid backflow.

[0046] A shutoff valve checking operation according to an embodiment of the present disclosure will now be described in more detail with reference to FIGS. 2 and 3. FIG.

[0047] 2 starts from step S100 in response to an instruction to perform a shutoff valve inspection operation from an operator (service engineer or user) via an operation panel of a centralized controller, a remote controller, etc. Note that the flow shown in Fig. 2 starts from a state in which the compressor 11 is stopped and all liquid shutoff valves 50 and gas shutoff valves 51 are open.

[0048] In step S101, the control device 26 first starts the fan operation. Because the state of the refrigeration cycle circuit can fluctuate due to factors such as the stop time before the shutoff valve inspection operation is started, the fan operation is performed for several minutes to adjust the state of the indoor units 40. Thereafter, in the loop of steps S102 to S111, the operations of steps S103 to S110 are performed for each indoor unit 40 to which the shutoff valve is connected.

[0049] In step S103, the control device 26 closes the liquid shutoff valve 50 connected to the target indoor unit 40, and maintains in an open state the gas shutoff valve 51 also connected to the target indoor unit 40. In step S104, the control device 26 ends the air blowing operation, and starts the cooling operation by operating the compressor 11 in the cooling cycle.

[0050] FIG. 3A is a diagram illustrating the refrigerant flow and valve open / close states during the cooling cycle of the shutoff valve inspection operation in the air conditioner 100 according to an embodiment of the present disclosure. In FIG. 3A, the refrigerant flow is indicated by solid arrows, and closed valves are grayed out. As shown in FIG. 3A, the first indoor unit 40a is selected as the target of processing, and the liquid shutoff valve 50a connected to the first indoor unit 40a is closed (gray). Because the upstream side of the indoor heat exchanger 41a in the first indoor unit 40a is closed, no refrigerant flows into it. In step S105, the control device 26 evaluates the operation of the liquid shutoff valve 50 (the first liquid shutoff valve 50a in FIG. 3A).

[0051] The performance of the liquid shutoff valve 50 can be evaluated, for example, using the temperature sensor 44 installed in the indoor unit 40. More specifically, the control device 26 determines whether the shutoff performance of the target liquid shutoff valve 50 is "good" or "poor" based on the value of the temperature sensor 44 of the target indoor unit 40. If the liquid shutoff valve 50 is properly closed, refrigerant will not flow, and there should be no difference between the intake air temperature and the discharge air temperature. Therefore, if the difference between the intake air temperature measured by the temperature sensor of the target indoor unit 40a and the discharge air temperature measured by the temperature sensor is within a predetermined threshold range, the performance is evaluated as "good" as normal. On the other hand, if the temperature difference is outside the predetermined threshold range, the performance is evaluated as "poor." Alternatively, instead of measuring the temperature difference at two points, the difference between the temperatures at two points in time may be calculated and the evaluation may be made based on the amount of temperature change.

[0052] In the above description, the evaluation operation of the liquid shutoff valve 50 is described as being determined based on the value of the temperature sensor 44 of the indoor unit 40. However, in other embodiments, the shutoff performance of the shutoff valve can be evaluated using a sensor other than the temperature sensor 44 of the indoor unit 40. For example, in another embodiment, temperature sensors are provided before and after the liquid shutoff valve, and temperature sensors are provided before and after the gas shutoff valve, and the shutoff performance of the liquid shutoff valve 50 can be determined from the difference in the temperature sensors before and after each shutoff valve. In the closed state, no refrigerant flows, so a temperature difference should occur between the temperature sensors before and after the shutoff valve. Conversely, if the temperature difference is outside a predetermined threshold range, the shutoff performance can be evaluated as normal and "good."

[0053] 2 , once the evaluation of the liquid shutoff valve 50 is complete, in step S106, the control device 26 stops operation of the compressor 11 and temporarily stops the air conditioner 100. In step S107, the control device 26 opens the liquid shutoff valve 50 connected to the target indoor unit 40 and closes the gas shutoff valve 51 also connected to the target indoor unit 40. In step S108, the control device 26 operates the compressor 11 in a heating cycle to start heating operation. The control device 26, for example, starts the compressor 11 and switches the four-way valve 12.

[0054] FIG. 3B is a diagram illustrating the refrigerant flow and valve open / close states during the heating cycle of the shutoff valve inspection operation in the air conditioner 100 according to an embodiment of the present disclosure. In FIG. 3B, the refrigerant flow is indicated by dotted arrows, and closed valves are similarly grayed out. In FIG. 3B, the gas shutoff valve 51a connected to the target first indoor unit 40a is closed (gray). Because the upstream side of the indoor heat exchanger 41a in the first indoor unit 40a is closed, no refrigerant flows into it. In step S109, the control device 26 performs an operational evaluation of the gas shutoff valve 51 (the first gas shutoff valve 51a in FIG. 3B) in the state shown in FIG. 3B. The operational evaluation of the gas shutoff valve 51 can be performed in the same manner as the liquid shutoff valve 50.

[0055] When evaluation of the gas cutoff valve 51 is completed following evaluation of the liquid cutoff valve 50, the control device 26 stops operation of the compressor 11 and shuts down the air conditioner 100 in step S110.

[0056] The operations of steps S103 to S110 are performed for each indoor unit 40 to which a shutoff valve is connected. When inspection of the shutoff valves for all indoor units 40 to which a shutoff valve is connected is completed, the process exits the loop of steps S102 to S111 and proceeds to step S112. In step S112, the control device 26 displays an operation evaluation of the liquid shutoff valve 50 and gas shutoff valve 51 for each indoor unit 40 on an operation panel of a centralized controller or the like, notifies the operator via the operation panel, and ends this inspection operation in step S113.

[0057] In the above description, the cooling cycle for evaluating the liquid shutoff valve 50 is performed first, followed by the heating cycle for evaluating the gas shutoff valve 51. However, the order of the cooling cycle for evaluating the liquid shutoff valve 50 and the heating cycle for evaluating the gas shutoff valve 51 can be selected as appropriate.

[0058] According to the above embodiment, in the cooling cycle and the heating cycle, the shutoff performance is evaluated with the upstream liquid shutoff valve 50 or gas shutoff valve 51 closed, respectively. This prevents refrigerant from accumulating in the indoor heat exchanger 41, thereby reducing the risk of liquid backflow when the valve is reopened. This allows for a highly reliable determination regardless of the refrigerant accumulation state. This makes it possible to more reliably check the shutoff performance of both the liquid shutoff valve 50 and the gas shutoff valve 51 while preventing deterioration in reliability due to liquid backflow.

[0059] In the embodiment described above, the gas shutoff valve 51 and liquid shutoff valve 50 are alternately closed and opened repeatedly for each of the indoor units 40a to 40c in order to evaluate their shutoff performance. Below, another preferred embodiment will be described in which the gas shutoff valve 51 and liquid shutoff valve 50 can be evaluated collectively for each of the indoor units 40a to 40c.

[0060] A shutoff valve checking operation according to another embodiment of the present disclosure will now be described in more detail with reference to FIGS.

[0061] The process shown in Fig. 4 starts from step S201 in response to an instruction to execute a shutoff valve inspection operation, etc. As with the embodiment described with reference to Fig. 2, the flow shown in Fig. 4 also starts from a state in which the compressor 11 is stopped and all liquid shutoff valves 50 and gas shutoff valves 51 are open. Note that for indoor units without shutoff valves (e.g., 40c), the valves are closed or slightly open to maintain the stopped state without operating (since heating is stopped, the indoor expansion valve 42c may be slightly open (open, but only by a small amount) to prevent refrigerant accumulation), and the fan 43 is stopped.

[0062] In step S202, the control device 26 starts the fan operation only in the indoor units with shutoff valves.

[0063] In step S203, the control device 26 closes the liquid shutoff valves 50 (e.g., 50a, 50b) connected to all of the shutoff valve-equipped indoor units 40 (e.g., 40a, 40b), and keeps the gas shutoff valves 51 (e.g., 51a, 51b) connected to all of the shutoff valve-equipped indoor units 40 (e.g., 40a, 40b) open. In step S204, the control device 26 ends the fan operation and starts the cooling operation by operating the compressor 11 in the cooling cycle.

[0064] FIG. 5A is a diagram illustrating the refrigerant flow and valve open / close states during the cooling cycle of a shutoff valve inspection operation in an air conditioner 100 according to another embodiment of the present disclosure. In FIG. 5A, the refrigerant flow is indicated by solid arrows, and closed valves are grayed out. As shown in FIG. 5A, the first and second indoor units 40a, 40b are assumed to be equipped with shutoff valves, and the liquid shutoff valves 50a, 50b connected to the first and second indoor units 40a, 40b are closed (grayed out). Because the upstream of the indoor heat exchangers 41a, 41b in the first and second indoor units 40a, 40b is closed, no refrigerant flows into them. In step S205, the control device 26 simultaneously evaluates the operation of the multiple liquid shutoff valves 50a, 50b.

[0065] As described above, the performance of the liquid shutoff valves 50a, 50b can be evaluated using the temperature sensor 44 installed in each indoor unit 40 or temperature sensors installed before and after each liquid shutoff valve 50. Because each temperature sensor is associated with each liquid shutoff valve 50, the performance of each liquid shutoff valve 50 can be evaluated based on the corresponding set of temperature sensors. Once the evaluation of the liquid shutoff valve 50 is complete, in step S206, the control device 26 stops operation of the compressor 11 and temporarily shuts down the air conditioner 100. In step S207, the control device 26 opens the liquid shutoff valves 50a, 50b connected to the first and second indoor units 40a, 40b and closes the gas shutoff valves 51a, 51b connected to the first and second indoor units 40a, 40b. In step S208, the control device 26 operates the compressor 11 in the heating cycle to start heating operation.

[0066] FIG. 5(B) is a diagram illustrating the refrigerant flow and valve open / close states during the heating cycle of the shutoff valve inspection operation in an air conditioner 100 according to another embodiment of the present disclosure. Similarly, in FIG. 5(B), the refrigerant flow is indicated by dotted arrows, and valves in the closed (or slightly open) state are grayed out. In FIG. 5(B), the first and second indoor units 40a, 40b are assumed to be equipped with shutoff valves, and the gas shutoff valves 51a, 51b connected to the first and second indoor units 40a, 40b are closed (grayed out). Because the upstream of the indoor heat exchangers 41a, 41b in the first and second indoor units 40a, 40b is closed, no refrigerant flows into them. In step S209, the control device 26 evaluates the operation of the gas shutoff valve 51 (the first and second gas shutoff valves 51a, 51b in FIG. 5(A)) in the state shown in FIG. 5(B). The performance of the gas cutoff valve 51 can be evaluated in the same manner as the liquid cutoff valve 50 .

[0067] When evaluation of all the liquid cutoff valves 50a, 50b and evaluation of the gas cutoff valves 51a, 51b are completed, the control device 26 stops operation of the compressor 11 and stops the air conditioner 100 in step S210.

[0068] In step S211, the control device 26 displays the operation evaluation of the liquid shut-off valve 50 and the gas shut-off valve 51 for each indoor unit 40 on an operation panel of a centralized controller or the like, notifies the operator via the operation panel, and ends this inspection operation in step S212.

[0069] 1 to 3, the other embodiments described above can shorten the inspection time because all liquid shutoff valves 50 or all gas shutoff valves 51 can be inspected simultaneously within a cycle. Also, by operating only the indoor units connected to the shutoff valves, refrigerant circulation to indoor units not connected to shutoff valves can be suppressed, reducing the impact of installation methods on the judgment.

[0070] As described above, according to an embodiment of the present disclosure, an air conditioner and a control method thereof can be provided that can more reliably confirm the shut-off performance of the liquid shut-off valve and the gas shut-off valve while preventing deterioration of reliability due to liquid backflow.

[0071] In the above-described embodiment, the air conditioner 100 has been described as an example of a refrigeration cycle apparatus according to an embodiment of the present disclosure. However, the refrigeration cycle apparatus is not limited to an air conditioner and may include what is also called a refrigeration air conditioning apparatus. Here, the term refrigeration air conditioning apparatus collectively refers to devices that use a refrigerant and a refrigeration cycle, such as the air conditioner described above, freezers, refrigerators, etc. More specifically, examples of refrigeration air conditioning apparatus include air conditioners such as package air conditioners and the multi-air conditioners for buildings described above, heat source equipment such as freezers and chilling units, commercial freezers such as showcases, refrigerator-freezers, unit coolers, and ice makers, transportation refrigeration equipment such as car air conditioners, and heat pump water heaters.

[0072] It should be noted that the embodiments of the present invention are not limited to the above-described embodiments and may include various modifications. For example, the above-described embodiments have been described in detail for ease of understanding, and are not necessarily limited to those including all of the described features. Furthermore, some of the features of one embodiment may be replaced with features of another embodiment, or features of one embodiment may be added to features of another embodiment. Furthermore, some of the features of each embodiment may be added to, deleted from, or replaced with other features.

[0073] 100...air conditioner, 10...outdoor unit, 11...compressor, 12...four-way valve, 13...outdoor heat exchanger, 14...outdoor expansion valve, 15...fan, 16...gas stop valve, 17...liquid stop valve, 20...subcooling heat exchanger, 21...subcooling main flow piping, 22...subcooling side flow piping, 23...subcooling expansion valve, 26...control device, 30...gas connection piping, 31...liquid connection piping, 40...indoor unit, 41...indoor heat exchanger, 42...indoor expansion valve, 43...fan, 44...temperature sensor, 50...liquid shut-off valve, 51...gas shut-off valve, 60...high-pressure side pressure sensor, 61...low-pressure side pressure sensor, 62...high-pressure-low-pressure bypass circuit, 63...high-low pressure bypass solenoid valve

Claims

1. A refrigeration cycle apparatus including a first device having a compressor and a second device having a heat exchanger, comprising: a liquid shutoff valve provided in a liquid pipe connecting the first device and the second device; a gas shutoff valve provided in a gas pipe connecting the first device and the second device; and a control device, wherein the control device, when the compressor is stopped, closes the liquid shutoff valve, opens the gas shutoff valve, and operates the compressor in a first cycle in which the liquid shutoff valve is upstream of the heat exchanger to evaluate the shutoff performance of the liquid shutoff valve; and when the compressor is stopped, opens the liquid shutoff valve, closes the gas shutoff valve, and operates the compressor in a second cycle in which the gas shutoff valve is upstream of the heat exchanger to evaluate the shutoff performance of the gas shutoff valve.

2. The refrigeration cycle apparatus according to claim 1, wherein the refrigeration cycle apparatus is an air conditioner, the first apparatus is an outdoor unit, the second apparatus includes a plurality of indoor units, the liquid shutoff valves include a plurality of liquid shutoff valves corresponding to the plurality of indoor units, and the gas shutoff valves include a plurality of gas shutoff valves corresponding to the plurality of indoor units, and the control device, in the shutoff valve inspection operation, operates the plurality of indoor units together to evaluate the shutoff performance of the plurality of liquid shutoff valves in the first cycle, which is a single cooling cycle, and evaluates the shutoff performance of the plurality of gas shutoff valves in the second cycle, which is a single heating cycle.

3. The refrigeration cycle apparatus according to claim 2, further comprising one or more other indoor units connected to the outdoor unit, wherein no shut-off valves are provided in one or more liquid pipes and one or more gas pipes between the one or more other indoor units and the outdoor unit, and wherein the control device controls the one or more other indoor units to maintain them in a stopped state during the shut-off valve inspection operation.

4. The refrigeration cycle device according to claim 1, wherein the second device has a temperature sensor, and the control device determines the shut-off performance of the liquid shut-off valve and the shut-off performance of the gas shut-off valve based on the value of the temperature sensor of the second device.

5. The refrigeration cycle device of claim 1, wherein the refrigeration cycle device includes first and second temperature sensors provided before and after the liquid shutoff valve, and third and fourth temperature sensors provided before and after the gas shutoff valve, and the control device determines the shutoff performance of the liquid shutoff valve based on the values ​​of the first and second temperature sensors, and determines the shutoff performance of the gas shutoff valve based on the values ​​of the third and fourth temperature sensors.

6. The refrigeration cycle device of claim 1, characterized in that the control device, before starting the compressor, performs air blowing operation, closes or opens the liquid shutoff valve, opens or closes the gas shutoff valve, starts the compressor, evaluates the shutoff performance of the liquid shutoff valve or the gas shutoff valve, stops the compressor, opens or closes the liquid shutoff valve, closes or opens the gas shutoff valve, starts the compressor, and evaluates the shutoff performance of the gas shutoff valve or the liquid shutoff valve.

7. A refrigeration cycle apparatus as described in claim 1, wherein the liquid piping includes a liquid connection piping connecting the second apparatus and the first apparatus, and a piping from the liquid side end of the first apparatus to the liquid side end of the heat exchanger, and the gas piping includes a gas connection piping connecting the second apparatus and the first apparatus, and a piping from the gas side end of the first apparatus to the gas side end of the heat exchanger.

8. A control method executed by a control device of a refrigeration cycle device including a first device having a compressor and a second device having a heat exchanger, the control device comprising: a step of closing a liquid shutoff valve provided in a liquid pipe connecting the first device and the second device and opening a gas shutoff valve provided in a gas pipe connecting the first device and the second device when the compressor is stopped; a step of operating the compressor in a first cycle in which the liquid shutoff valve is upstream of the heat exchanger and evaluating the shutoff performance of the liquid shutoff valve; a step of opening the liquid shutoff valve and closing the gas shutoff valve when the compressor is stopped; and a step of operating the compressor in a second cycle in which the gas shutoff valve is upstream of the heat exchanger and evaluating the shutoff performance of the gas shutoff valve.

9. The control method according to claim 8, wherein the refrigeration cycle device is an air conditioner, the first device is an outdoor unit, the second device includes a plurality of indoor units, the liquid shutoff valves include a plurality of liquid shutoff valves corresponding to the plurality of indoor units, and the gas shutoff valves include a plurality of gas shutoff valves corresponding to the plurality of indoor units, and the control device includes the steps of: operating the plurality of indoor units together in a shutoff valve inspection operation; evaluating the shutoff performance of the plurality of liquid shutoff valves all at once in the first cycle, which is a single cooling cycle; and evaluating the shutoff performance of the plurality of gas shutoff valves all at once in the second cycle, which is a single heating cycle.

10. A control method as described in claim 8, comprising the steps of: receiving an instruction to start an inspection operation; operating an air blower before starting the compressor; setting the liquid shutoff valve to a closed or open state and the gas shutoff valve to an open or closed state, and then starting the compressor; stopping the compressor after evaluating the shutoff performance of the liquid shutoff valve or the gas shutoff valve; setting the liquid shutoff valve to an open or closed state and the gas shutoff valve to a closed or open state, and then starting the compressor; and evaluating the shutoff performance of the gas shutoff valve or the liquid shutoff valve.

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