Air conditioning system, control device, and control method

Abstract

This air conditioning system (1) comprises: a refrigerant circuit (2) that circulates a refrigerant; and at least one control device (110, 210, 310) that controls the refrigerant circuit. The refrigerant circuit is provided with: an outdoor unit (10); at least one indoor unit (20) including an expansion valve (25) for expanding the refrigerant flowing in from the outdoor unit; and at least one blocking device (30) for blocking the flow of the refrigerant between the outdoor unit and the at least one indoor unit. The at least one control device opens the expansion valve when the flow of the refrigerant is blocked by the at least one blocking device.

Description

Air conditioning system, control device, and control method

[0001] The present disclosure relates to an air conditioning system, a control device, and a control method.

[0002] Conventionally, air conditioning systems configured to cool or heat a room by circulating a refrigerant through a refrigerant circuit including an outdoor unit and an indoor unit have been known. For example, Japanese Patent Application Laid-Open Publication No. 2014-228224 (Patent Document 1) discloses an air conditioning system configured such that, in the outdoor unit, gas refrigerant flowing in from an indoor unit is compressed by a compressor and then heat-exchanged in an outdoor heat exchanger to convert it into liquid refrigerant. In the indoor unit, the liquid refrigerant flowing in from the outdoor unit is expanded by an expansion valve and then heat-exchanged in an indoor heat exchanger to convert it into gas refrigerant, which then flows out to the outdoor unit again. Furthermore, the air conditioning system disclosed in Japanese Patent Application Laid-Open Publication No. 2014-228224 is configured such that, by closing the expansion valve of the indoor unit, refrigerant from the outdoor unit does not flow into the indoor heat exchanger when the indoor unit is stopped.

[0003] JP 2014-228224 A

[0004] In an air conditioning system, for example, when an abnormality is detected, a shutoff device may be used to shut off the flow of refrigerant between the outdoor unit and the indoor unit, thereby minimizing damage and ensuring a safe state. In the air conditioning system disclosed in JP 2014-228224 A, when the shutoff device as described above shuts off the refrigerant, the refrigerant does not flow from the outdoor unit to the indoor unit, and the air conditioning system is controlled to a stopped state or a thermostat-off state. When controlled to a stopped state or a thermostat-off state, the expansion valve of the indoor unit is closed to prevent unintentional discharge of cold or warm air from the indoor unit to the outside. If the expansion valve of the indoor unit is closed while the flow of refrigerant between the outdoor unit and the indoor unit is shut off, liquid refrigerant may become trapped in a sealed state between the shutoff device and the expansion valve, potentially causing problems such as deformation of the piping or the expansion valve.

[0005] The present disclosure has been made to solve the above-mentioned problem, and aims to provide a technology that prevents malfunctions when the flow of refrigerant between the outdoor unit and the indoor unit is blocked.

[0006] The air conditioning system according to the present disclosure includes a refrigerant circuit that circulates a refrigerant and at least one control device that controls the refrigerant circuit. The refrigerant circuit includes an outdoor unit, at least one indoor unit including an expansion valve that expands the refrigerant flowing from the outdoor unit, and at least one shutoff device that shuts off the flow of refrigerant between the outdoor unit and the at least one indoor unit. The at least one control device opens the expansion valve when the flow of refrigerant is shut off by the at least one shutoff device.

[0007] A control device according to the present disclosure controls a refrigerant circuit that circulates a refrigerant. The refrigerant circuit includes an outdoor unit, at least one indoor unit including an expansion valve that expands the refrigerant flowing from the outdoor unit, and at least one shutoff device that shuts off the flow of refrigerant between the outdoor unit and the at least one indoor unit. The control device opens the expansion valve when the flow of refrigerant is shut off by the at least one shutoff device.

[0008] A control method according to the present disclosure is a control method for controlling a refrigerant circuit that circulates a refrigerant. The refrigerant circuit includes an outdoor unit, at least one indoor unit including an expansion valve that expands the refrigerant flowing from the outdoor unit, and at least one shutoff device that shuts off the flow of refrigerant between the outdoor unit and the at least one indoor unit. The control method includes, as processing executed by a computer, a step of determining whether an abnormality in the refrigerant circuit has been detected, a step of shutting off the flow of refrigerant with the at least one shutoff device when the abnormality in the refrigerant circuit has been detected, and a step of opening an expansion valve when the flow of refrigerant has been shut off by the at least one shutoff device.

[0009] According to the present disclosure, when the flow of refrigerant between the outdoor unit and the indoor unit is blocked by the shutoff device, the expansion valve that expands the refrigerant flowing in from the outdoor unit is opened. This prevents the liquid refrigerant flowing from the outdoor unit to the indoor unit from being trapped in a sealed state between the shutoff device and the expansion valve, making it possible to avoid problems such as deformation of the piping or the expansion valve.

[0010] 1 is a diagram showing the configuration of an air conditioning system according to Embodiment 1. FIG. 1 is a diagram showing a simplified configuration of an air conditioning system according to Embodiment 1. FIG. 2 is a diagram showing communication paths in the air conditioning system according to Embodiment 1. FIG. 3 is a diagram showing the state of piping in an indoor unit when a shutoff valve and an expansion valve are closed in the air conditioning system according to Embodiment 1. FIG. 4 is a flowchart for explaining the shutoff process performed by the air conditioning system according to Embodiment 1. FIG. 5 is a diagram showing the state of liquid piping and gas piping when shutoff process is performed in the air conditioning system according to Embodiment 1. FIG. 6 is a flowchart for explaining the shutoff process performed by an air conditioning system according to Embodiment 2. FIG. 7 is a diagram showing the state of piping in an indoor unit when shutoff process is performed in the air conditioning system according to Embodiment 2. FIG. 8 is a flowchart for explaining the shutoff process performed by an air conditioning system according to Embodiment 3. FIG. 9 is a diagram showing the state of liquid piping and gas piping when shutoff process is performed in the air conditioning system according to Embodiment 3. FIG. 10 is a flowchart for explaining the shutoff process performed by an air conditioning system according to Embodiment 4. FIG. 11 is a diagram showing the state of liquid piping and gas piping when shutoff process is performed in the air conditioning system according to Embodiment 4 when the previous state was the thermo-off state. FIG. 10 is a diagram showing the states of the liquid piping and the gas piping when a shut-off process is executed in an air conditioning system according to embodiment 4 when the immediately preceding state is a thermo-on state. FIG. 11 is a diagram showing, in a simplified form, the configuration of an air conditioning system according to embodiment 5. FIG. 12 is a diagram showing, in a simplified form, the configuration of an air conditioning system according to embodiment 6. FIG. 13 is a diagram showing, in a simplified form, the configuration of an air conditioning system according to embodiment 7. FIG. 14 is a diagram showing, in a simplified form, the configuration of an air conditioning system according to embodiment 7.

[0011] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings. While multiple embodiments will be described below, it is anticipated from the beginning that the configurations described in each embodiment will be appropriately combined. Note that identical or corresponding parts in the drawings will be designated by the same reference numerals, and their description will not be repeated.

[0012] Embodiment 1. An air conditioning system 1 according to embodiment 1 will be described with reference to Figures 1 to 6. Figure 1 is a diagram showing the configuration of the air conditioning system 1 according to embodiment 1. Figure 2 is a diagram showing a simplified configuration of the air conditioning system 1 according to embodiment 1. Note that Figures 1 and 2 functionally show the connection relationships and arrangement of the devices in the air conditioning system 1, and do not necessarily show the physical arrangement in space.

[0013] 1 and 2 , the air conditioning system 1 includes a refrigerant circuit 2, a plurality of control devices 110, 210, 310 that control various actuators included in the refrigerant circuit 2, and a shutoff device 30 that shuts off (stops) the flow of refrigerant in the refrigerant circuit 2. The refrigerant circuit 2 includes an outdoor unit 10 and an indoor unit 20. The outdoor unit 10 and the indoor unit 20 are connected via the shutoff device 30, and refrigerant circulates between the outdoor unit 10 and the indoor unit 20.

[0014] The outdoor unit 10 is generally installed outdoors in an area that is not subject to air conditioning, and includes a four-way valve 12, a compressor 11, an outdoor heat exchanger 13, and an outdoor fan 14. The control device 110 is mounted on the outdoor unit 10.

[0015] The four-way valve 12 includes connection ports 12A, 12B, 12C, and 12D. Connection port 12A of the four-way valve 12 is connected to the discharge port 11A of the compressor 11 via piping 51. Connection port 12B of the four-way valve 12 is connected to the outdoor heat exchanger 13 via piping 52. Connection port 12C of the four-way valve 12 is connected to the shutoff device 30 via piping 57. Connection port 12D of the four-way valve 12 is connected to the suction port 11B of the compressor 11 via piping 58. The four-way valve 12 is configured to switch its internal communication state under the control of the control device 110.

[0016] The compressor 11 is configured to operate and stop, and to change its rotational speed during operation, under the control of the control device 110. The control device 110 controls the compressor 11 to arbitrarily change the drive frequency of the compressor 11. The compressor 11 changes the number of rotations per unit time, i.e., the rotational speed, in response to changes in the drive frequency, thereby changing the amount of refrigerant discharged. Various types of compressors can be used as the compressor 11, and for example, a scroll type, a rotary type, a screw type, etc. can be used as the compressor 11.

[0017] The outdoor heat exchanger 13 exchanges heat between the refrigerant and air drawn in from the outdoors by the outdoor fan 14, i.e., outside air. One end of the outdoor heat exchanger 13 is connected to the connection port 12B of the four-way valve 12 via a pipe 52. The other end of the outdoor heat exchanger 13 is connected to the shutoff device 30 via a pipe 53.

[0018] The outdoor fan 14 is configured to operate and stop, and to change its rotation speed when operating, under the control of the control device 110. The control device 110 controls the outdoor fan 14 to arbitrarily change the drive frequency of the outdoor fan 14. The outdoor fan 14 changes the number of rotations per unit time, i.e., the rotation speed, in accordance with the change in drive frequency, thereby changing the amount of air sent to the outdoor heat exchanger 13.

[0019] The control device 110 is an example of an "outdoor control device." The control device 110 includes a processor 111 and a memory 112. The control device 110 communicates with each actuator included in the outdoor unit 10, such as the compressor 11, the four-way valve 12, and the outdoor fan 14, and controls the actuators. The control device 110 does not necessarily have to be mounted on the outdoor unit 10, and may be separate from the outdoor unit 10.

[0020] The processor 111 is a computing entity (computer) that controls each actuator of the outdoor unit 10 by executing various programs. The processor 111 is configured, for example, as a microcontroller, a central processing unit (CPU), a micro processing unit (MPU), a tensor processing unit (TPU), or a graphics processing unit (GPU). The processor 111 has the function of performing various processes by executing programs, but some or all of these functions may be implemented using dedicated hardware circuits such as an application-specific integrated circuit (ASIC) or a field-programmable gate array (FPGA). The processor 111 is not limited to processors in the narrow sense that perform processes using stored programs, such as a CPU, MPU, TPU, or GPU, but may also include hardwired circuits such as an ASIC or FPGA. Furthermore, the processor 111 is not limited to von Neumann computers such as a CPU or GPU, but may also be configured as non-von Neumann computers such as a quantum computer or an optical computer. The processor 111 may also be interpreted as a processing circuitry that executes a predetermined process. The processor 111 may be configured as a single chip or multiple chips. Furthermore, the processor 111 and related processing circuits may be configured as multiple computers interconnected by wire or wirelessly via a local area network or a wireless network. The processor 111 and related processing circuits may be configured as a cloud computer that performs remote calculations based on input data and outputs the calculation results to another device located at a distance.

[0021] The memory 112 provides a storage area for storing program code, work memory, etc., when the processor 111 executes various programs. The memory 112 may be one or more non-transitory computer-readable media. Examples of the memory 112 include volatile memory such as dynamic random access memory (DRAM) or static random access memory (SRAM), or non-volatile memory such as read-only memory (ROM) or flash memory. The memory 112 may also be one or more computer-readable storage media. Examples of the memory 112 include storage devices such as hard disk drives (HDDs) and solid-state drives (SSDs). The processor 111 controls the actuators of the outdoor unit 10 by executing a control program 113 stored in the memory 112.

[0022] The indoor unit 20 is generally installed in an indoor space to be air-conditioned, and includes an indoor heat exchanger 23, an indoor fan 24, and an expansion valve 25. The control device 210 is mounted on the indoor unit 20.

[0023] The indoor heat exchanger 23 exchanges heat between the refrigerant and air drawn from the room by the indoor fan 24. One end of the indoor heat exchanger 23 is connected to the expansion valve 25 via a pipe 55. The other end of the indoor heat exchanger 23 is connected to the shutoff device 30 via a pipe 56.

[0024] The indoor fan 24 is configured to operate and stop, and to change its rotation speed when operating, under the control of the control device 210. The control device 210 controls the indoor fan 24 to arbitrarily change the drive frequency of the indoor fan 24. The indoor fan 24 changes the number of rotations per unit time, i.e., the rotation speed, in accordance with the change in drive frequency, thereby changing the amount of air sent to the indoor heat exchanger 23.

[0025] The expansion valve 25 is an electric valve or a solenoid valve whose opening is adjusted under the control of the control device 210. The expansion valve 25 expands the refrigerant flowing in from the outdoor unit 10 to reduce its pressure, and then discharges the refrigerant obtained by the reduction in pressure. The control device 210 controls the expansion valve 25 to adjust the amount of reduction in pressure of the refrigerant and the amount of refrigerant flowing through the expansion valve 25. For example, the control device 210 can close the expansion valve 25 to prevent the refrigerant from flowing through the expansion valve 25, and can open the expansion valve 25 to allow the refrigerant to flow through the expansion valve 25. Furthermore, the control device 210 can reduce the amount of refrigerant flowing through the expansion valve 25 by narrowing the opening of the expansion valve 25, and can increase the amount of refrigerant flowing through the expansion valve 25 by widening the opening of the expansion valve 25. One end of the expansion valve 25 is connected to the shutoff device 30 via a pipe 54. The other end of the expansion valve 25 is connected to the indoor heat exchanger 23 via a pipe 55.

[0026] The expansion valve 25 may be mounted on the shutoff device 30 instead of the indoor unit 20. In this case, the opening degree of the expansion valve 25 may be adjusted under the control of a control device 310 mounted on the shutoff device 30.

[0027] The control device 210 is an example of an "indoor control device." The control device 210 includes a processor 211 and a memory 212. The control device 210 communicates with each actuator included in the indoor unit 20, such as the indoor fan 24 and the expansion valve 25, and controls each of the actuators. Note that the control device 210 does not necessarily have to be mounted in the indoor unit 20, and may be separate from the indoor unit 20.

[0028] The processor 211 has a configuration similar to that of the processor 111 and is a computing entity (computer) that controls each actuator of the indoor unit 20 by executing various programs. The processor 211 can also be interpreted as a processing circuit that executes predetermined processing. The processor 211 and related processing circuits may be configured as multiple computers interconnected by wire or wirelessly via a local area network or a wireless network. The processor 211 and related processing circuits may be configured as a cloud computer that performs remote calculations based on input data and outputs the calculation results to another device in a remote location.

[0029] The memory 212 has a configuration similar to that of the memory 112, and provides a storage area for storing program code, work memory, etc. when the processor 211 executes various programs. The memory 212 may be one or more non-transitory computer readable media. The memory 212 may also be one or more computer readable storage media. The processor 211 controls each actuator of the indoor unit 20 by executing a control program 213 stored in the memory 212.

[0030] The shutoff device 30 includes a shutoff valve 31 and a shutoff valve 32 for shutting off the flow of refrigerant between the outdoor unit 10 and the indoor unit 20. One end of the shutoff valve 31 is connected to the outdoor heat exchanger 13 of the outdoor unit 10 via a pipe 53. The other end of the shutoff valve 31 is connected to the expansion valve 25 of the indoor unit 20 via a pipe 54. One end of the shutoff valve 32 is connected to the indoor heat exchanger 23 of the indoor unit 20 via a pipe 56. The other end of the shutoff valve 32 is connected to the four-way valve 12 of the outdoor unit 10 via a pipe 57.

[0031] The shutoff valve 31 is an electric valve or a solenoid valve that shuts off the flow of refrigerant between the outdoor unit 10 and the indoor unit 20 under the control of the control device 310. Specifically, when the shutoff valve 31 is open under the control of the control device 310, the path between the pipe 53 on the outdoor unit 10 side and the pipe 54 on the indoor unit 20 side is connected, and the refrigerant flows through the path between the outdoor unit 10 and the indoor unit 20. On the other hand, when the shutoff valve 31 is closed (fully closed) under the control of the control device 310, the path between the pipe 53 on the outdoor unit 10 side and the pipe 54 on the indoor unit 20 side is shut off, and the refrigerant does not flow through the path between the outdoor unit 10 and the indoor unit 20.

[0032] The shutoff valve 32 is an electric valve or a solenoid valve that shuts off the flow of refrigerant between the outdoor unit 10 and the indoor unit 20 under the control of the control device 310. Specifically, when the shutoff valve 32 is open under the control of the control device 310, the path between the pipe 57 on the outdoor unit 10 side and the pipe 56 on the indoor unit 20 side is connected, and the refrigerant flows through the path between the outdoor unit 10 and the indoor unit 20. On the other hand, when the shutoff valve 32 is closed (fully closed) under the control of the control device 310, the path between the pipe 57 on the outdoor unit 10 side and the pipe 56 on the indoor unit 20 side is shut off, and the refrigerant does not flow through the path between the outdoor unit 10 and the indoor unit 20.

[0033] The control device 310 is an example of a "shutoff control device." The control device 310 includes a processor 311 and a memory 312. The control device 310 communicates with each actuator included in the shutoff device 30, such as the shutoff valve 31 and the shutoff valve 32, and controls the actuators. Note that the control device 310 does not necessarily have to be mounted on the shutoff device 30, and may be separate from the shutoff device 30.

[0034] The processor 311 has a configuration similar to that of the processor 111 and the processor 211, and is a computing entity (computer) that controls each actuator of the cutoff device 30 by executing various programs. The processor 311 can also be interpreted as a processing circuit that executes predetermined processing. The processor 311 and related processing circuits may be configured as a plurality of computers interconnected by wire or wirelessly via a local area network or a wireless network. The processor 311 and related processing circuits may be configured as a cloud computer that performs remote calculations based on input data and outputs the calculation results to another device in a remote location.

[0035] The memory 312 has a configuration similar to that of the memory 112 and the memory 212, and provides a storage area for storing program code, work memory, etc. when the processor 311 executes various programs. The memory 312 may be one or more non-transitory computer-readable media. The memory 312 may also be one or more computer-readable storage media. The processor 311 controls each actuator of the shutoff device 30 by executing a control program 313 stored in the memory 312.

[0036] The air conditioning system 1 configured as described above is controlled to one of a plurality of operation modes including a cooling operation mode for cooling the indoor space and a heating operation mode for heating the indoor space.

[0037] First, the operation of the air conditioning system 1 in the cooling operation mode will be described. As shown by the solid lines in Figure 1, in the cooling operation mode, the internal communication state of the four-way valve 12 is such that connection port 12A is connected to connection port 12B and connection port 12C is connected to connection port 12D. In other words, in the cooling operation mode, the intake port 11B of the compressor 11 is connected to the indoor heat exchanger 23 side and the discharge port 11A of the compressor 11 is connected to the outdoor heat exchanger 13 side.

[0038] The compressor 11 draws in the low-temperature, low-pressure gas refrigerant from the indoor heat exchanger 23 and compresses the drawn gas refrigerant to increase the pressure of the gas refrigerant. The compressor 11 discharges the high-temperature, high-pressure gas refrigerant obtained by the compression to the outdoor heat exchanger 13.

[0039] In the cooling operation mode, the outdoor heat exchanger 13 functions as a condenser. The outdoor heat exchanger 13 exchanges heat between the high-temperature, high-pressure gas refrigerant from the compressor 11 and air drawn in from outdoors by the outdoor fan 14. The gas refrigerant that has released heat into the air through this heat exchange condenses inside the outdoor heat exchanger 13, changing into a high-temperature, high-pressure liquid refrigerant. In the cooling operation mode, a shutoff valve 31 of the shutoff device 30 is disposed between the outdoor unit 10 and the refrigerant inlet side of the expansion valve 25. The high-temperature, high-pressure liquid refrigerant obtained by the outdoor heat exchanger 13 flows out to the expansion valve 25 via the shutoff valve 31 of the shutoff device 30.

[0040] The expansion valve 25 reduces the pressure of the high-temperature, high-pressure liquid refrigerant from the outdoor heat exchanger 13. The low-temperature, low-pressure gas-liquid two-phase refrigerant obtained by the pressure reduction in the expansion valve 25 flows out to the indoor heat exchanger 23.

[0041] In the cooling operation mode, the indoor heat exchanger 23 functions as an evaporator. The indoor heat exchanger 23 exchanges heat between the low-temperature, low-pressure gas-liquid two-phase refrigerant from the expansion valve 25 and air drawn from the room by the indoor fan 24. The gas-liquid two-phase refrigerant absorbs heat from the air through this heat exchange, evaporating inside the indoor heat exchanger 23 and changing into low-temperature, low-pressure gas refrigerant. In the cooling operation mode, a shutoff valve 32 of the shutoff device 30 is disposed between the outdoor unit 10 and the refrigerant outlet side of the expansion valve 25. The low-temperature, low-pressure gas refrigerant obtained by the indoor heat exchanger 23 flows out to the compressor 11 via the shutoff valve 32 of the shutoff device 30. The air whose heat has been absorbed by the gas refrigerant in the indoor heat exchanger 23 is sent back into the room. This cools the room.

[0042] In this way, in the cooling operation mode, the refrigerant flows through the compressor 11, the outdoor heat exchanger 13 (condenser), the expansion valve 25, and the indoor heat exchanger 23 (evaporator) in this order.

[0043] Next, the operation of the air conditioning system 1 in the heating operation mode will be described. As shown by the dashed lines in Figure 1, in the heating operation mode, the internal communication state of the four-way valve 12 is such that connection port 12A is connected to connection port 12C and connection port 12B is connected to connection port 12D. In other words, in the heating operation mode, the intake port 11B of the compressor 11 is connected to the outdoor heat exchanger 13 side and the discharge port 11A of the compressor 11 is connected to the indoor heat exchanger 23 side.

[0044] The compressor 11 draws in the low-temperature, low-pressure gas refrigerant that has flowed in from the outdoor heat exchanger 13, and compresses the drawn gas refrigerant to increase the pressure of the gas refrigerant. In the heating operation mode, a shutoff valve 32 of the shutoff device 30 is arranged between the outdoor unit 10 and the refrigerant inlet side of the expansion valve 25. The compressor 11 discharges the high-temperature, high-pressure gas refrigerant obtained by compression to the indoor heat exchanger 23 via the shutoff valve 32 of the shutoff device 30.

[0045] In the heating operation mode, the indoor heat exchanger 23 functions as a condenser. The indoor heat exchanger 23 exchanges heat between the high-temperature, high-pressure gas refrigerant from the compressor 11 and air drawn in from the indoor space by the indoor fan 24. The gas refrigerant that has released heat to the air through this heat exchange condenses inside the indoor heat exchanger 23 and changes into high-temperature, high-pressure liquid refrigerant. The high-temperature, high-pressure liquid refrigerant obtained by the indoor heat exchanger 23 flows out to the expansion valve 25. The air that has absorbed heat from the gas refrigerant in the indoor heat exchanger 23 is sent back into the indoor space. This heats the indoor space.

[0046] The expansion valve 25 reduces the pressure of the high-temperature, high-pressure liquid refrigerant from the indoor heat exchanger 23. In the heating operation mode, a shutoff valve 31 of the shutoff device 30 is arranged between the outdoor unit 10 and the refrigerant outlet side of the expansion valve 25. The low-temperature, low-pressure gas-liquid two-phase refrigerant obtained by the expansion valve 25 flows out to the outdoor heat exchanger 13 via the shutoff valve 31 of the shutoff device 30.

[0047] In the heating operation mode, the outdoor heat exchanger 13 functions as an evaporator. The outdoor heat exchanger 13 exchanges heat between the low-temperature, low-pressure gas-liquid two-phase refrigerant from the expansion valve 25 and air drawn in from outdoors by the outdoor fan 14. The gas-liquid two-phase refrigerant absorbs heat from the air through this heat exchange, evaporating inside the outdoor heat exchanger 13 and changing into low-temperature, low-pressure gas refrigerant. The low-temperature, low-pressure gas refrigerant obtained by the outdoor heat exchanger 13 flows out to the compressor 11.

[0048] In this way, in the heating operation mode, the refrigerant flows through the compressor 11, the indoor heat exchanger 23 (condenser), the expansion valve 25, and the outdoor heat exchanger 13 (evaporator) in this order.

[0049] In the following, the path between the shutoff valve 31 of the shutoff device 30 and the expansion valve 25 of the indoor unit 20 (path including the pipe 54), through which mainly liquid refrigerant passes, is also referred to as the "liquid pipe." Furthermore, the path between the expansion valve 25 of the indoor unit 20 and the shutoff valve 32 of the shutoff device 30 (path including the pipe 55 and the pipe 56), through which mainly gas refrigerant passes, is also referred to as the "gas pipe."

[0050] Fig. 3 is a diagram showing communication paths in the air conditioning system 1 according to Embodiment 1. As shown in Fig. 3, the control device 110 of the outdoor unit 10, the control device 210 of the indoor unit 20, and the control device 310 of the shutoff device 30 can communicate with each other via the communication paths, and signals can be transmitted and received between the respective control devices.

[0051] 1 and 2 , the air conditioning system 1 further includes a sensor 40 that detects an abnormality in the refrigerant circuit 2. For example, the sensor 40 is a refrigerant sensor that is mounted in the indoor unit 20 and detects refrigerant leakage from the refrigerant circuit 2.

[0052] When the sensor 40 detects a gas of a certain concentration or higher, such as propane, which constitutes the refrigerant, near the indoor unit 20, the sensor 40 transmits a detection signal indicating that an abnormality has been detected to the control device 110 of the outdoor unit 10 and the control device 310 of the shutoff device 30. When the control device 310 receives a detection signal from the sensor 40, it closes the shutoff valves 31, 32 to shut off the flow of refrigerant between the outdoor unit 10 and the indoor unit 20.

[0053] As described above, in the air conditioning system 1, if an abnormality is detected by the sensor 40, the flow of refrigerant between the outdoor unit 10 and the indoor unit 20 is blocked by the blocking device 30, thereby minimizing damage and ensuring a safe state.

[0054] When shutoff is performed by the shutoff device 30, refrigerant does not flow from the outdoor unit 10 to the indoor unit 20, and the air conditioning system 1 is controlled to a thermo-off state or a stopped state. The stopped state is a state in which the air conditioning system 1 is stopped and the compressor 11 and the outdoor fan 14 are stopped. The thermo-off state is a state in which the air conditioning system 1 is operating but the compressor 11 and the outdoor fan 14 are stopped and no air conditioning capacity is being exerted. The thermo-on state is a state in which the compressor 11 and the outdoor fan 14 are operating and air conditioning capacity is being exerted.

[0055] 4 is a diagram showing the state of the piping of the indoor unit 20 when the shutoff valves 31, 32 are closed and the expansion valve 25 is closed in the air conditioning system 1 according to Embodiment 1. As shown in FIG. 4, when a refrigerant leak occurs in the gas piping, the shutoff valves 31, 32 are closed to control the system to a stopped state or a thermo-off state. Furthermore, when the expansion valve 25 of the indoor unit 20 is closed, the liquid refrigerant is sealed and trapped in the liquid piping. In this state, if heat from the outside is applied to the liquid refrigerant trapped in the liquid piping, the liquid refrigerant will expand in the liquid piping, which may cause problems such as deformation of the liquid piping or the expansion valve 25.

[0056] Therefore, the air conditioning system 1 of embodiment 1 is configured to prevent the above-mentioned problems from occurring by executing a shutdown process to open the expansion valve 25 when the flow of refrigerant between the outdoor unit 10 and the indoor unit 20 is shut off by the shut-off device 30.

[0057] A specific flow of the shutdown processing executed by the air conditioning system 1 will be described with reference to Fig. 5. Fig. 5 is a flowchart for explaining the shutdown processing executed by the air conditioning system 1 according to Embodiment 1. The control device 110 of the outdoor unit 10 executes the processing of the flowchart shown in Fig. 5 by having the processor 111 execute the control program 113 stored in the memory 112. The control device 210 of the indoor unit 20 executes the processing of the flowchart shown in Fig. 5 by having the processor 211 execute the control program 213 stored in the memory 212. The control device 310 of the shutdown device 30 executes the processing of the flowchart shown in Fig. 5 by having the processor 311 execute the control program 313 stored in the memory 312. Note that in the diagram, "S" is used as an abbreviation for "STEP".

[0058] 5, the indoor unit 20 (control device 210) determines whether or not an abnormality has been detected in the refrigerant circuit 2 (S21). For example, the indoor unit 20 (control device 210) determines whether or not a detection signal indicating that an abnormality has been detected has been received from the sensor 40.

[0059] If the indoor unit 20 (controller 210) has not detected an abnormality in the refrigerant circuit 2 (NO in S21), it ends this process. On the other hand, if the indoor unit 20 (controller 210) detects an abnormality in the refrigerant circuit 2 (YES in S21), it transmits an abnormality signal to the outdoor unit 10 (controller 110) and the shutoff device 30 (controller 310) to notify them of the detection of the abnormality (S22).

[0060] The shutoff device 30 (control device 310) determines whether or not an abnormality signal has been received from the indoor unit 20 (control device 210) (S31). If the shutoff device 30 (control device 310) has not received an abnormality signal from the indoor unit 20 (control device 210) (NO in S31), the shutoff device 30 (control device 310) ends this process. On the other hand, if the shutoff device 30 (control device 310) has received an abnormality signal from the indoor unit 20 (control device 210) (YES in S31), the shutoff device 30 (control device 310) closes the shutoff valves 31, 32 based on the abnormality signal to shut off the flow of refrigerant between the outdoor unit 10 and the indoor unit 20 (S32), and ends this process.

[0061] The outdoor unit 10 (control device 110) determines whether or not an abnormality signal has been received from the indoor unit 20 (control device 210) (S11). If the outdoor unit 10 (control device 110) has not received an abnormality signal from the indoor unit 20 (control device 210) (NO in S11), the outdoor unit 10 (control device 110) ends this process. On the other hand, if the outdoor unit 10 (control device 110) has received an abnormality signal from the indoor unit 20 (control device 210) (YES in S11), the outdoor unit 10 (control device 110) sends an open signal to the indoor unit 20 (control device 210) to open the expansion valve 25 based on the abnormality signal (S12), and ends this process.

[0062] After transmitting the abnormality signal in S22, the indoor unit 20 (controller 210) determines whether or not an open signal has been received from the outdoor unit 10 (controller 110) (S23). If the indoor unit 20 (controller 210) has not received an open signal from the outdoor unit 10 (controller 110) (NO in S23), the indoor unit 20 (controller 210) repeats the processing of S23. On the other hand, if the indoor unit 20 (controller 210) has received an open signal from the outdoor unit 10 (controller 110) (YES in S23), the indoor unit 20 (controller 210) opens (fully opens) the expansion valve 25 based on the open signal (S24), and ends this processing.

[0063] When shutoff device 30 (control device 310) closes shutoff valves 31, 32, it may transmit a close signal to outdoor unit 10 (control device 110) to notify that shutoff valves 31, 32 have been closed, and when outdoor unit 10 (control device 110) receives a close signal from shutoff device 30 (control device 310), it may transmit an open signal to indoor unit 20 (control device 210). In this way, indoor unit 20 (control device 210) can open (fully open) expansion valve 25 after shutoff device 30 (control device 310) has reliably closed shutoff valves 31, 32.

[0064] As described above, in the air conditioning system 1 according to the first embodiment, when the sensor 40 detects an abnormality in the refrigerant circuit 2, the shutoff valves 31, 32 are closed in the shutoff device 30, thereby minimizing damage and ensuring a safe state. Furthermore, when the sensor 40 detects an abnormality and the shutoff valves 31, 32 are closed, the expansion valve 25 in the indoor unit 20 is opened (fully opened), so the liquid refrigerant that flows from the outdoor unit 10 into the indoor unit 20 is not trapped in a sealed state in the liquid piping.

[0065] For example, FIG. 6 illustrates the states of the liquid and gas pipes when a shutdown process is performed in the air conditioning system 1 according to Embodiment 1. As shown in FIG. 6 , even when a refrigerant leak occurs in the gas pipe and the shutoff valves 31 and 32 are closed and the system is controlled to a stopped state or thermo-off state, the expansion valve 25 of the indoor unit 20 is opened (fully open), allowing liquid refrigerant to move from the liquid pipe to the gas pipe. Because gas refrigerant exists in the gas pipe, the liquid refrigerant that moves from the liquid pipe to the gas pipe exists in the same space as the gas refrigerant in the gas pipe. Furthermore, because the liquid refrigerant that flows into the gas pipe leaks to the outside, the liquid refrigerant is not sealed and confined in the liquid pipe. Even if the gas pipe is also filled with liquid refrigerant, the liquid refrigerant that moves from the liquid pipe to the gas pipe combines with the liquid refrigerant in the gas pipe, increasing the heat capacity of the entire liquid refrigerant and making it less likely to rise in temperature. This allows the air conditioning system 1 to avoid problems such as deformation of the liquid pipe or the expansion valve 25.

[0066] Any abnormality that occurs in the refrigerant circuit 2 is notified to an external maintenance server (not shown) by the sensor 40, the outdoor unit 10 (controller 110), the indoor unit 20 (controller 210), or the shut-off device 30 (controller 310), and repairs or other measures are then carried out by a worker who confirms the abnormality.

[0067] Embodiment 2 An air conditioning system 1 according to Embodiment 2 will be described with reference to Figures 7 and 8. The air conditioning system 1 according to Embodiment 2 may be configured so that the indoor unit 20 (control device 210) opens a portion of the expansion valve 25.

[0068] For example, Figure 7 is a flowchart for explaining the shutdown process executed by the air conditioning system 1 according to embodiment 2. As shown in Figure 7, after transmitting the abnormality signal in S22, the indoor unit 20 (controller 210) determines whether or not it has received an open signal from the outdoor unit 10 (controller 110) (S23). If it has received an open signal from the outdoor unit 10 (controller 110) (YES in S23), it opens a portion of the expansion valve 25 based on the open signal (S24A). For example, if the opening degree of the expansion valve 25 when fully open is defined as 100%, the indoor unit 20 (controller 210) opens the expansion valve 25 to a degree between 2% and 10% based on the open signal.

[0069] As described above, in the air conditioning system 1 according to embodiment 2, when the shut-off valves 31, 32 are closed when an abnormality is detected by the sensor 40, a portion of the expansion valve 25 in the indoor unit 20 is opened, so that the liquid refrigerant flowing from the outdoor unit 10 into the indoor unit 20 is not trapped in a sealed state in the liquid piping.

[0070] For example, Figure 8 is a diagram showing the states of the liquid piping and the gas piping when the shutoff process is performed in the air conditioning system 1 according to embodiment 2. As shown in Figure 8, even when a refrigerant leak occurs in the gas piping and the shutoff valves 31 and 32 are closed and the system is controlled to a stopped state or thermo-off state, a portion of the expansion valve 25 of the indoor unit 20 is opened, allowing liquid refrigerant to move little by little from the liquid piping to the gas piping. Because the liquid refrigerant that flows into the gas piping leaks to the outside, the liquid refrigerant is not trapped in the liquid piping in a sealed state. This allows the air conditioning system 1 to avoid problems such as deformation of the liquid piping or the expansion valve 25.

[0071] Furthermore, when the leakage rate of the refrigerant leaking to the outside is greater than the movement rate of the refrigerant moving from the liquid piping to the gas piping, the leakage rate of the refrigerant leaking to the outside varies depending on the movement rate of the refrigerant moving from the liquid piping to the gas piping. Therefore, in a situation where the leakage rate of the refrigerant leaking to the outside is greater than the movement rate of the refrigerant moving from the liquid piping to the gas piping, the air conditioning system 1 can adjust the leakage rate of the refrigerant leaking to the outside by adjusting the opening degree of the expansion valve 25 of the indoor unit 20.

[0072] Embodiment 3 An air conditioning system 1 according to Embodiment 3 will be described with reference to Figures 9 and 10. The air conditioning system 1 according to Embodiment 3 may be configured so that the indoor unit 20 (control device 210) repeatedly opens and closes the expansion valve 25.

[0073] For example, Fig. 9 is a flowchart for explaining the shut-off process executed by the air conditioning system 1 according to Embodiment 3. As shown in Fig. 9, after transmitting the abnormality signal in S22, the indoor unit 20 (controller 210) determines whether or not an open signal has been received from the outdoor unit 10 (controller 110) (S23), and if an open signal has been received from the outdoor unit 10 (controller 110) (YES in S23), opens the expansion valve 25 based on the open signal (S24).

[0074] After transmitting the open signal to the indoor unit 20 (controller 210) in S12, the outdoor unit 10 (controller 110) determines whether a predetermined first time has elapsed (S13). If the first time has not elapsed (NO in S13), the outdoor unit 10 (controller 110) repeats the process of S13. On the other hand, if the first time has elapsed (YES in S13), the outdoor unit 10 (controller 110) transmits a close signal to close the expansion valve 25 to the indoor unit 20 (controller 210) (S14).

[0075] After transmitting the close signal to the indoor unit 20 (controller 210), the outdoor unit 10 (controller 110) determines whether a predetermined second time has elapsed (S15). If the second time has not elapsed (NO in S15), the outdoor unit 10 (controller 110) repeats the process of S15. On the other hand, if the second time has elapsed (YES in S15), the outdoor unit 10 (controller 110) returns to the process of S12 and again transmits an open signal to the indoor unit 20 (controller 210). Note that the second time may be the same as the first time (for example, one hour), or may be a different time.

[0076] After opening the expansion valve 25 in S24, the indoor unit 20 (controller 210) determines whether or not a close signal has been received from the outdoor unit 10 (controller 110) (S25). If the indoor unit 20 (controller 210) has not received a close signal from the outdoor unit 10 (controller 110) (NO in S25), the indoor unit 20 (controller 210) repeats the processing of S25. On the other hand, if the indoor unit 20 (controller 210) has received a close signal from the outdoor unit 10 (controller 110) (YES in S25), the indoor unit 20 (controller 210) closes (fully closes) the expansion valve 25 based on the close signal (S26) and returns to the processing of S23.

[0077] As described above, in the air conditioning system 1 according to embodiment 3, when the shut-off valves 31, 32 are closed when an abnormality is detected by the sensor 40, the expansion valve 25 in the indoor unit 20 is periodically opened and closed repeatedly, so that the liquid refrigerant flowing from the outdoor unit 10 into the indoor unit 20 is not trapped in a sealed state in the liquid piping.

[0078] For example, Figure 10 is a diagram showing the states of the liquid piping and the gas piping when the shutoff process is executed in the air conditioning system 1 according to embodiment 3. As shown in Figure 10, even when a refrigerant leak occurs in the gas piping and the shutoff valves 31 and 32 are closed and the system is controlled to a stopped state or thermo-off state, the expansion valve 25 of the indoor unit 20 periodically opens and closes, allowing liquid refrigerant to periodically move from the liquid piping to the gas piping. Liquid refrigerant that flows into the gas piping leaks to the outside, so the liquid refrigerant is not trapped in the liquid piping in a sealed state. This allows the air conditioning system 1 to avoid problems such as deformation of the liquid piping or the expansion valve 25.

[0079] Furthermore, if the leakage rate of the refrigerant leaking to the outside is greater than the movement rate of the refrigerant moving from the liquid pipe to the gas pipe, the leakage rate of the refrigerant leaking to the outside varies depending on the movement rate of the refrigerant moving from the liquid pipe to the gas pipe. Therefore, by periodically opening and closing the expansion valve 25, the air conditioning system 1 can suppress the increase in pressure inside the liquid pipe and the gas pipe and reduce the average leakage rate of the refrigerant leaking to the outside.

[0080] 11 to 13, an air conditioning system 1 according to a fourth embodiment will be described. The air conditioning system 1 according to the fourth embodiment may be configured to close the expansion valve 25 when a predetermined time has elapsed since the expansion valve 25 was opened, in a thermo-on state in which the compressor operates, when the flow of refrigerant is blocked by the shutoff device 30.

[0081] For example, Fig. 11 is a flowchart for explaining the shut-off process executed by the air conditioning system 1 according to Embodiment 4. As shown in Fig. 11, after transmitting the abnormality signal in S22, the indoor unit 20 (controller 210) determines whether or not an open signal has been received from the outdoor unit 10 (controller 110) (S23), and if an open signal has been received from the outdoor unit 10 (controller 110) (YES in S23), opens the expansion valve 25 based on the open signal (S24).

[0082] After transmitting an open signal to the indoor unit 20 (controller 210) in S12, the outdoor unit 10 (controller 110) determines whether the previous state (e.g., the state before the abnormality was detected) was the thermo-on state (S16). If the previous state was not the thermo-on state (NO in S16), the outdoor unit 10 (controller 110) terminates this process. On the other hand, if the previous state was the thermo-on state (YES in S16), the outdoor unit 10 (controller 110) determines whether a predetermined time has elapsed (S17). If the predetermined time has not elapsed (NO in S17), the outdoor unit 10 (controller 110) repeats the process of S17. On the other hand, if the predetermined time has elapsed (YES in S17), the outdoor unit 10 (controller 110) transmits a close signal to close the expansion valve 25 to the indoor unit 20 (controller 210) (S18), and terminates this process.

[0083] After opening the expansion valve 25 in S24, the indoor unit 20 (controller 210) determines whether the previous state (e.g., the state before the abnormality was detected) was the thermo-on state (S27). If the previous state was not the thermo-on state (NO in S27), the indoor unit 20 (controller 210) terminates this process. On the other hand, if the previous state was the thermo-on state (YES in S27), the indoor unit 20 (controller 210) determines whether a close signal has been received from the outdoor unit 10 (controller 110) (S28). If the indoor unit 20 (controller 210) has not received a close signal from the outdoor unit 10 (controller 110) (NO in S28), the indoor unit 20 (controller 210) repeats the process of S28. On the other hand, if the indoor unit 20 (controller 210) receives a close signal from the outdoor unit 10 (controller 110) (YES in S28), the indoor unit 20 (controller 210) closes (fully closes) the expansion valve 25 based on the close signal (S29), and terminates this process.

[0084] As described above, in the air conditioning system 1 according to embodiment 4, when the shut-off valves 31, 32 are closed when an abnormality is detected by the sensor 40, the expansion valve 25 in the indoor unit 20 is opened, so that the liquid refrigerant flowing from the outdoor unit 10 into the indoor unit 20 is not trapped in a sealed state in the liquid piping.

[0085] Furthermore, if the state before the abnormality is detected is the thermo-off state, a pressure difference is unlikely to occur between the liquid pipe and the gas pipe, so not only the liquid pipe but also the gas pipe may be filled with liquid refrigerant. On the other hand, if the state before the abnormality is detected is the thermo-on state, a pressure difference occurs between the liquid pipe and the gas pipe, so gas refrigerant may be present in the gas pipe. In this regard, the air conditioning system 1 keeps the expansion valve 25 open if the state before the abnormality is detected is the thermo-off state, but closes the expansion valve 25 when a predetermined time has elapsed since opening it if the state before the abnormality is detected is the thermo-on state. This prevents liquid refrigerant from being trapped in the liquid pipe in a sealed state if the state before the abnormality is detected is the thermo-off state, and can again separate the liquid pipe and the gas pipe from each other after the liquid refrigerant that flows into the gas pipe from the liquid pipe combines with the gas refrigerant in the gas pipe if the state before the abnormality is detected is the thermo-on state.

[0086] For example, Fig. 12 is a diagram showing the states of the liquid piping and the gas piping when the shutoff process is executed in the air conditioning system 1 according to embodiment 4 when the previous state was the thermo-off state. As shown in Fig. 12, when the state before the abnormality is detected is the thermo-off state, the gas piping may be filled with liquid refrigerant, so the air conditioning system 1 keeps the expansion valve 25 open. This allows the air conditioning system 1 to avoid the liquid refrigerant being trapped in the liquid piping in a sealed state.

[0087] 13 is a diagram showing the states of the liquid piping and the gas piping when a shutoff process is executed in the case where the previous state was the thermo-on state in the air conditioning system 1 according to embodiment 4. As shown in FIG. 13 , if the state before an abnormality is detected is the thermo-on state, there is a possibility that gas refrigerant is present in the gas piping. Therefore, the air conditioning system 1 opens the expansion valve 25 to equalize the proportion of gas present in the liquid piping and the gas piping, and then closes the expansion valve 25 after a predetermined time has elapsed. As a result, the air conditioning system 1 can again separate the liquid piping and the gas piping after the liquid refrigerant that flows from the liquid piping into the gas piping combines with the gas refrigerant in the gas piping, thereby reducing the amount of refrigerant leaking from the gas piping.

[0088] Embodiment 5 An air conditioning system 1 according to embodiment 5 will be described with reference to Figure 14. Figure 14 is a diagram showing a simplified configuration of an air conditioning system 1A according to embodiment 5. In the air conditioning system 1A according to embodiment 5, a plurality of indoor units may be connected to one outdoor unit 10 and one shutoff device 30. Note that in the air conditioning system 1A shown in Figure 14, two indoor units 20A and 20B are connected to one outdoor unit 10 and one shutoff device 30, but three or more indoor units may be connected to one outdoor unit 10 and one shutoff device 30.

[0089] 14 , the indoor unit 20A includes an indoor heat exchanger 23A, an expansion valve 25A, a control device 210A, and a sensor 40A. One end of the expansion valve 25A is connected to a pipe 54 that is connected to a shutoff valve 31 via a pipe 54A. The other end of the expansion valve 25A is connected to one end of the indoor heat exchanger 23A via a pipe 55A. The other end of the indoor heat exchanger 23A is connected to a pipe 56 that is connected to the shutoff valve 32 via a pipe 56A.

[0090] The indoor unit 20B includes an indoor heat exchanger 23B, an expansion valve 25B, a control device 210B, and a sensor 40B. One end of the expansion valve 25B is connected to a pipe 54 that is connected to the shutoff valve 31 via a pipe 54B. The other end of the expansion valve 25B is connected to one end of the indoor heat exchanger 23B via a pipe 55B. The other end of the indoor heat exchanger 23B is connected to a pipe 56 that is connected to the shutoff valve 32 via a pipe 56B.

[0091] When an abnormality is detected by sensor 40A or sensor 40B, air conditioning system 1A shuts off the flow of refrigerant between outdoor unit 10 and each of the multiple indoor units 20A, 20B by closing shutoff valves 31, 32 with shutoff device 30. Furthermore, when shutoff valves 31, 32 are closed, air conditioning system 1A opens multiple expansion valves 25A, 25B included in each of the multiple indoor units 20A, 20B.

[0092] In this way, in air conditioning system 1A, when sensor 40A or 40B detects an abnormality, shutoff valves 31 and 32 are closed in shutoff device 30, thereby minimizing damage and ensuring a safe state. Furthermore, when shutoff valves 31 and 32 are closed upon detection of an abnormality by sensor 40A or 40B, expansion valves 25A and 25B in indoor units 20A and 20B are opened, so that liquid refrigerant flowing from outdoor unit 10 to indoor unit 20 is not trapped in a sealed state in the liquid piping. This makes it possible for air conditioning system 1A to avoid problems such as deformation of the liquid piping or expansion valve 25.

[0093] Embodiment 6 An air conditioning system 1B according to Embodiment 6 will be described with reference to Figures 15 and 16. Figure 15 is a diagram showing a simplified configuration of the air conditioning system 1B according to Embodiment 6. In the air conditioning system 1B according to Embodiment 6, multiple shutoff devices may be connected to one outdoor unit 10, and multiple indoor units may be connected to each of the multiple shutoff devices. Note that in the air conditioning system 1B shown in Figures 15 and 16, two shutoff devices 30A, 30B are connected to one outdoor unit 10, and two indoor units 20A, 20B are connected to each of the two shutoff devices 30A, 30B, but three or more shutoff devices may be connected to one outdoor unit 10, and three or more indoor units may be connected to each of the three or more shutoff devices.

[0094] 15 , the shutoff device 30A includes a shutoff valve 31A, a shutoff valve 32A, and a control device 310A. One end of the shutoff valve 31A is connected to a pipe 53 that is connected to the outdoor unit 10 via a pipe 53A. The other end of the shutoff valve 31A is connected to the indoor unit 20A via a pipe 54A. One end of the shutoff valve 32A is connected to the indoor unit 20A via a pipe 56A. The other end of the shutoff valve 32A is connected to a pipe 57 that is connected to the outdoor unit 10 via a pipe 57A.

[0095] The indoor unit 20A includes an indoor heat exchanger 23A, an expansion valve 25A, a control device 210A, and a sensor 40A. One end of the expansion valve 25A is connected to a shutoff valve 31A via a pipe 54A. The other end of the expansion valve 25A is connected to one end of the indoor heat exchanger 23A via a pipe 55A. The other end of the indoor heat exchanger 23A is connected to a shutoff valve 32A via a pipe 56A.

[0096] The shutoff device 30B includes a shutoff valve 31B, a shutoff valve 32B, and a control device 310B. One end of the shutoff valve 31B is connected to a pipe 53 connected to the outdoor unit 10 via a pipe 53B. The other end of the shutoff valve 31B is connected to the indoor unit 20B via a pipe 54B. One end of the shutoff valve 32B is connected to the indoor unit 20B via a pipe 56B. The other end of the shutoff valve 32B is connected to a pipe 57 connected to the outdoor unit 10 via a pipe 57B.

[0097] The indoor unit 20B includes an indoor heat exchanger 23B, an expansion valve 25B, a control device 210B, and a sensor 40B. One end of the expansion valve 25B is connected to a shutoff valve 31B via a pipe 54B. The other end of the expansion valve 25B is connected to one end of the indoor heat exchanger 23B via a pipe 55B. The other end of the indoor heat exchanger 23B is connected to a shutoff valve 32B via a pipe 56B.

[0098] Fig. 16 is a diagram showing communication paths in an air conditioning system 1B according to Embodiment 6. As shown in Fig. 16, the control device 110 of the outdoor unit 10, the control device 210A of the indoor unit 20A, the control device 210B of the indoor unit 20B, the control device 310A of the shutoff device 30A, and the control device 310B of the shutoff device 30B can communicate with each other via the communication paths, and signals can be sent and received between the respective control devices.

[0099] When an abnormality is detected by sensor 40A, air conditioning system 1B shuts off the flow of refrigerant between outdoor unit 10 and indoor unit 20A by closing shutoff valves 31A and 32A with shutoff device 30A. At this time, shutoff valves 31B and 32B are not closed by shutoff device 30B, so the flow of refrigerant between outdoor unit 10 and indoor unit 20B is not shut off. Furthermore, when shutoff valves 31A and 32A are closed, air conditioning system 1B opens expansion valve 25A included in indoor unit 20A.

[0100] Furthermore, when an abnormality is detected by sensor 40B, air conditioning system 1B shuts off the flow of refrigerant between outdoor unit 10 and indoor unit 20B by closing shutoff valves 31B and 32B with shutoff device 30B. At this time, shutoff valves 31A and 32A are not closed by shutoff device 30A, so the flow of refrigerant between outdoor unit 10 and indoor unit 20A is not shut off. Furthermore, when shutoff valves 31B and 32B are closed, air conditioning system 1B opens expansion valve 25B included in indoor unit 20B.

[0101] In this way, in air conditioning system 1B, only the shutoff valve connected to the indoor unit 20A or 20B in which an abnormality is detected is closed, minimizing damage and ensuring a safe state. Furthermore, if an abnormality is detected and the shutoff valve is closed, the expansion valve in the indoor unit in which the abnormality was detected opens, so liquid refrigerant is not trapped in a sealed state in the liquid piping. This makes it possible for air conditioning system 1B to avoid problems such as deformation of the liquid piping or expansion valve 25.

[0102] Seventh Embodiment An air conditioning system 1C according to a seventh embodiment will be described with reference to Figures 17 and 18. Figure 17 is a diagram showing a simplified configuration of the air conditioning system 1C according to the seventh embodiment. The air conditioning system 1C according to the seventh embodiment further includes a diverter device 60 that connects the outdoor unit 10 and at least one shutoff device 30. In the example of Figures 17 and 18, the air conditioning system 1C according to the seventh embodiment adds the diverter device 60 to the air conditioning system 1B according to the sixth embodiment. The diverter device 60 connects the outdoor unit 10 and each of the multiple shutoff devices 30A, 30B, and includes a control device 610. Although not shown, the control device 610, like the control devices 110, 210, and 310, includes a processor and a memory that stores a control program.

[0103] 17, one end of the flow dividing device 60 is connected to the outdoor unit 10 via pipes 53C and 57C. The other end of the flow dividing device 60 is connected to the shutoff device 30A via pipes 53A and 57A, and is connected to the shutoff device 30B via pipes 53B and 57B.

[0104] Figure 18 is a diagram showing communication paths in an air conditioning system 1C pertaining to Embodiment 7. As shown in Figure 18, the control device 110 of the outdoor unit 10, the control device 210A of the indoor unit 20A, the control device 210B of the indoor unit 20B, the control device 310A of the shutoff device 30A, the control device 310B of the shutoff device 30B, and the control device 610 of the shunt device 60 can communicate with each other via communication paths, and signals can be sent and received between the respective control devices.

[0105] In the air conditioning system 1C, the control device 110 of the outdoor unit 10 executes the shutoff processing shown in Figures 5, 7, 9, and 11. Specifically, when the flow dividing device 60 (control device 610) receives an abnormality signal from the indoor unit 20A (control device 210A), it sends an open signal to the indoor unit 20A (control device 210A) to open the expansion valve 25A based on the abnormality signal, thereby preventing the liquid refrigerant from being trapped in a sealed state in the liquid piping of the indoor unit 20A. Furthermore, when the flow dividing device 60 (control device 610) receives an abnormality signal from the indoor unit 20B (control device 210B), it sends an open signal to the indoor unit 20B (control device 210B) to open the expansion valve 25B based on the abnormality signal, thereby preventing the liquid refrigerant from being trapped in a sealed state in the liquid piping of the indoor unit 20B.

[0106] [Modifications] The present disclosure is not limited to the above-described embodiment, and various modifications and applications are possible. Modifications that can be applied to the present disclosure will be described below.

[0107] In the air conditioning system 1, a plurality of either the indoor units 20 or the shutoff devices 30 may be provided. In addition, in the air conditioning system 1, a plurality of both the indoor units 20 and the shutoff devices 30 may be provided.

[0108] The shutoff device 30 may be mounted on the diverter device 60 or the indoor unit 20. In this case, the control device 310 of the shutoff device 30 may be integrated into the control device 610 of the diverter device 60 or the control device 210 of the indoor unit 20.

[0109] The sensor 40 is not limited to being mounted in the indoor unit 20, but may also be mounted in the outdoor unit 10. Furthermore, the sensor 40 is not limited to being installed inside the outdoor unit 10 or the indoor unit 20, but may also be installed outside the outdoor unit 10 or the indoor unit 20 (for example, on a floor, wall, or pillar).

[0110] The sensor 40 may output a detection signal indicating that an abnormality has been detected not only to the indoor unit 20 (control device 210) but also to the shutoff device 30 (control device 310). In this case, the shutoff device 30 (control device 310) may close the shutoff valves 31, 32 based on the detection signal received from the sensor 40.

[0111] The sensor 40 is not limited to a refrigerant sensor, but may also be a power supply sensor configured to output a detection signal when the amount of power supplied to the outdoor unit 10, the indoor unit 20, or the shut-off device 30 falls below a threshold value.

[0112] The air conditioning system 1 is not limited to an air conditioner that performs both cooling and heating operations, but may also be a cooling-only air conditioner or refrigerator. In this case, one of the shutoff valves 31 and 32 of the shutoff device 30 may be an electrically operated or solenoid valve, and the other may be a check valve that is not electrically operated. For example, in the refrigerant circuit 2 shown in FIG. 1 , if the refrigerant flows through the compressor 11, the outdoor heat exchanger 13 (condenser), the expansion valve 25, and the indoor heat exchanger 23 (evaporator) in that order, the shutoff valve 31 may be an electrically operated or solenoid valve, and the shutoff valve 32 may be a check valve configured to allow refrigerant to flow only in one direction, from the indoor unit 20 to the outdoor unit 10. In this case, the shutoff device 30 (controller 310) only needs to close the shutoff valve 31 when an abnormality is detected by the sensor 40. This prevents refrigerant from flowing from the outdoor unit 10 to the indoor unit 20 when an abnormality is detected. The "shut-off valve" is not limited to an electrically operated valve or solenoid valve that opens and closes electrically, but may also be any other valve that does not open and close electrically, as long as it is a valve that can shut off the flow of refrigerant between the outdoor unit 10 and the indoor unit 20.

[0113] The embodiments disclosed herein should be considered to be illustrative in all respects and not restrictive. The scope of the present disclosure is defined by the claims, not by the description of the above embodiments, and is intended to include all modifications within the meaning and scope of the claims.

[0114] 1, 1A, 1B, 1C Air conditioning system, 2 Refrigerant circuit, 10 Outdoor unit, 11 Compressor, 11A Discharge port, 11B Intake port, 12 Four-way valve, 12A, 12B, 12C, 12D Connection port, 13 Outdoor heat exchanger, 14 Outdoor fan, 20, 20A, 20B Indoor unit, 23, 23A, 23B Indoor heat exchanger, 24 Indoor fan, 25, 25A, 25B Expansion valve, 30, 30A, 30B Shutoff device, 31, 31A, 31B, 32, 32A, 32B Shutoff valve, 40, 40A, 40B Sensors, 51, 52, 53, 53A, 53B, 53C, 54, 54A, 54B, 55, 55A, 55B, 56, 56A, 56B, 57, 57A, 57B, 57C, 58 Piping, 60 Diversion device, 110, 210, 210A, 210B, 310, 310A, 310B, 610 Control device, 111, 211, 311 Processor, 112, 212, 312 Memory, 113, 213, 313 Control program.

Claims

1. An air conditioning system comprising a refrigerant circuit for circulating a refrigerant and at least one control device for controlling the refrigerant circuit, wherein the refrigerant circuit comprises an outdoor unit, at least one indoor unit including an expansion valve for expanding the refrigerant flowing in from the outdoor unit, and at least one shut-off device for shutting off the flow of the refrigerant between the outdoor unit and the at least one indoor unit, and the at least one control device opens the expansion valve when the flow of the refrigerant is shut off by the at least one shut-off device.

2. The air conditioning system according to claim 1, wherein the at least one control device opens a part of the expansion valve when the flow of the refrigerant is shut off by the at least one shut-off device.

3. The air conditioning system according to claim 1, wherein the at least one control device periodically repeats opening and closing of the expansion valve when the flow of the refrigerant is shut off by the at least one shut-off device.

4. The air conditioning system according to any one of claims 1 to 3, further comprising a sensor for detecting an abnormality in the refrigerant circuit, wherein the at least one shut-off device shuts off the flow of the refrigerant when the abnormality is detected by the sensor.

5. The air conditioning system according to claim 4, wherein the sensor includes a refrigerant sensor for detecting leakage of the refrigerant from the refrigerant circuit.

6. The outdoor unit includes a compressor, and the at least one control device closes the expansion valve when a predetermined time has elapsed after opening the expansion valve when the flow of the refrigerant is shut off by the at least one shut-off device and the compressor is in an operating state. The air conditioning system according to any one of claims 1 to 5.

7. The at least one shut-off device includes a first shut-off valve disposed between the outdoor unit and the refrigerant inlet side of the expansion valve and a second shut-off valve disposed between the outdoor unit and the refrigerant outlet side of the expansion valve, and the at least one shut-off device closes the first shut-off valve and the second shut-off valve to shut off the flow of the refrigerant. The air conditioning system according to any one of claims 1 to 6.

8. The at least one control device includes an outdoor control device for controlling the outdoor unit, an indoor control device for controlling the at least one indoor unit, and a shut-off control device for controlling the at least one shut-off device. When the indoor control device detects an abnormality in the refrigerant circuit, it transmits an abnormality signal for notifying the detection of the abnormality to the outdoor unit and the at least one shut-off device. The at least one shut-off device shuts off the flow of the refrigerant based on the abnormality signal. The outdoor control device transmits an opening signal for opening the expansion valve to the indoor control device based on the abnormality signal. The indoor control device opens the expansion valve based on the opening signal. The air conditioning system according to any one of claims 1 to 7.

9. The at least one indoor unit includes a plurality of indoor units. The at least one shut-off device shuts off the flow of the refrigerant between the outdoor unit and each of the plurality of indoor units. When the flow of the refrigerant is shut off by the at least one shut-off device, the at least one control device opens the expansion valve included in each of the plurality of indoor units. The air conditioning system according to any one of claims 1 to 8.

10. The at least one shut-off device includes a plurality of shut-off devices. Each of the plurality of shut-off devices shuts off the flow of the refrigerant between the outdoor unit and each of the plurality of indoor units. When the flow of the refrigerant is shut off by the plurality of shut-off devices, the at least one control device opens the expansion valve included in each of the plurality of indoor units. The air conditioning system according to claim 9.

11. The air conditioning system according to any one of claims 1 to 10 further includes a flow-dividing device that connects the outdoor unit and each of the at least one shut-off devices. The flow-dividing device includes the at least one control device.

12. A control device for controlling a refrigerant circuit that circulates refrigerant. The refrigerant circuit includes an outdoor unit, at least one indoor unit including an expansion valve for expanding the refrigerant flowing in from the outdoor unit, and at least one shut-off device for shutting off the flow of the refrigerant between the outdoor unit and the at least one indoor unit. The control device opens the expansion valve when the flow of the refrigerant is shut off by the at least one shut-off device.

13. A control method for controlling a refrigerant circuit that circulates a refrigerant, the refrigerant circuit including an outdoor unit, at least one indoor unit including an expansion valve that expands the refrigerant flowing in from the outdoor unit, and at least one shutoff device that shuts off the flow of the refrigerant between the outdoor unit and the at least one indoor unit, and as processing executed by a computer, a step of determining whether an abnormality in the refrigerant circuit has been detected, a step of shutting off the flow of the refrigerant by the at least one shutoff device when an abnormality in the refrigerant circuit has been detected, and a step of opening the expansion valve when the flow of the refrigerant has been shut off by the at least one shutoff device.

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