Air conditioning device

Abstract

An air conditioning device (1) comprises an outdoor heat exchanger (3), an indoor heat exchanger (4), a refrigerant sensor (25), a first cutoff device (21), a second cutoff device (22), and a control device (100). If the refrigerant sensor (25) has detected refrigerant leakage, the control device (100) performs control such that the first cutoff device (21) and the second cutoff device (22) are each put into a second state. The second cutoff device (22) includes a first expansion valve (221) and a second expansion valve (222) connected in series. The first expansion valve (221) and the second expansion valve (222) are each operated so as to be closed in an incomplete cutoff state when a full-closing command is received from the control device (100). The second state includes the incomplete cutoff state of the first expansion valve (221) and the second expansion valve (222).

Description

air conditioning equipment

[0001] The present disclosure relates to an air conditioning apparatus.

[0002] Air conditioners are required to have sufficient safety measures against refrigerant leaks. International Publication No. 2018 / 096576 (Patent Document 1) discloses an air conditioner in which a shutoff device is provided in a refrigerant pipe connecting an indoor heat exchanger and an outdoor heat exchanger. The shutoff device shuts off the flow of refrigerant in the refrigerant pipe in the event of a refrigerant leak, thereby preventing the refrigerant from leaking from the refrigerant circuit into the air-conditioned space.

[0003] International Publication No. 2018 / 096576

[0004] In the air conditioner disclosed in Patent Document 1, only one of the refrigerant piping that allows refrigerant to flow into the indoor heat exchanger and the refrigerant piping that allows refrigerant to flow out of the indoor heat exchanger is shut off by the shutoff device. Therefore, the air conditioner disclosed in Patent Document 1 does not have a sufficient function of preventing refrigerant from leaking from the refrigerant circuit into the air-conditioned space.

[0005] However, if a refrigerant leak occurs and both the refrigerant pipe that flows into the indoor heat exchanger and the refrigerant pipe that flows out of the indoor heat exchanger are shut off with shutoff devices, the refrigerant becomes sealed in the refrigerant pipe between the two shutoff devices, creating a so-called liquid-sealed state. Because the pressure in the sealed refrigerant pipe increases with temperature, there is a risk of damage to the refrigerant pipe and the refrigerant circuit including the indoor heat exchanger.

[0006] The present disclosure has been made in consideration of the above-described situation, and its purpose is to suppress refrigerant leakage using a relatively inexpensive configuration without creating a liquid-sealed state when a refrigerant leakage is detected.

[0007] The present disclosure relates to an air conditioning apparatus. The air conditioning apparatus comprises an outdoor unit having an outdoor heat exchanger, an indoor unit having an indoor heat exchanger and blowing conditioned air into an air-conditioned space, a refrigerant sensor disposed in the air-conditioned space and detecting refrigerant leakage, a shut-off device that changes between a first state for circulating refrigerant and a second state for preventing refrigerant leakage, and a control device, wherein the indoor heat exchanger is connected to a first refrigerant piping and a second refrigerant piping for circulating refrigerant between the outdoor heat exchanger and the indoor heat exchanger, and the shut-off device includes a first shut-off device provided on the first refrigerant piping and a second shut-off device provided on the second refrigerant piping, and when a refrigerant leakage is detected by the refrigerant sensor, the control device controls each of the first shut-off device and the second shut-off device to the second state, and the second shut-off device includes a first expansion valve and a second expansion valve connected in series, and each of the first expansion valve and the second expansion valve operates to close in an incomplete shut-off state in which the flow of refrigerant cannot be completely shut off when a fully closed command is received from the control device, and the second state includes the incomplete shut-off state of each of the first expansion valve and the second expansion valve.

[0008] According to the present disclosure, when a refrigerant leak occurs, the refrigerant leak can be suppressed with a relatively inexpensive configuration without creating a liquid-sealed state.

[0009] FIG. 1 is a diagram showing the configuration of an air conditioning apparatus according to a first embodiment. FIG. 2 is a graph showing the relationship between the opening degree of an expansion valve used in a shutoff device and the refrigerant flow rate. FIG. 3 is a conceptual diagram showing the amount of refrigerant passing through when the shutoff device is fully closed. FIG. 4 is a block diagram showing the configurations of a control device arranged in an outdoor unit, a control device arranged in an indoor unit, a shutoff device, and a remote control. FIG. 5 is a flowchart showing the procedure of processing executed by a control device when a refrigerant leak is detected. FIG. 6 is a flowchart showing the procedure of processing executed by a control device to identify the location of the refrigerant leak. FIG. 7 is a diagram showing the configuration of an air conditioning apparatus according to a second embodiment. FIG. 8 is a diagram showing the configuration of an air conditioning apparatus according to a third embodiment. FIG. 9 is a diagram showing the configuration of an air conditioning apparatus according to a fourth embodiment.

[0010] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings. While multiple embodiments will be described below, it was originally intended that the configurations described in each embodiment be combined as appropriate. Note that identical or corresponding parts in the drawings will be designated by the same reference numerals, and their description will not be repeated.

[0011] Embodiment 1. Fig. 1 is a diagram showing the configuration of an air conditioning apparatus 1 according to embodiment 1. Note that Fig. 1 functionally shows the connection relationships and arrangement of the devices in the air conditioning apparatus 1, and does not necessarily show the physical arrangement in space.

[0012] Referring to FIG. 1 , the air conditioning apparatus 1 includes an outdoor unit 10 and an indoor unit 20. The outdoor unit 10 has an outdoor heat exchanger 3. The indoor unit 20 has an indoor heat exchanger 4 and blows conditioned air into an air-conditioned space (room) R1. Here, the air-conditioned space refers to the space that is the target of air conditioning by the indoor unit 20. Therefore, for example, in a configuration in which it is not expected that conditioned air from the indoor unit 20 will be sent to the attic of a room, the attic does not qualify as an air-conditioned space. In other words, even if the attic is a part of a room, in a configuration in which it is expected that conditioned air from the indoor unit 20 will be sent there, both the room and the attic qualify as air-conditioned spaces.

[0013] The outdoor unit 10 further includes a compressor 2, a four-way valve 5, an expansion valve 6, and an accumulator 7. The compressor 2, the outdoor heat exchanger 3, the indoor heat exchanger 4, the four-way valve 5, the expansion valve 6, and the accumulator 7, as well as refrigerant piping connecting these, form a path (refrigerant circuit) through which the refrigerant flows. The refrigerant piping includes refrigerant piping 51 and 52 for circulating the refrigerant between the outdoor heat exchanger 3 and the indoor heat exchanger 4. The indoor heat exchanger 4 is connected to the refrigerant piping 51 and 52. The refrigerant piping 51 is connected to port P1 of the indoor heat exchanger 4. The refrigerant piping 52 is connected to port P2 of the indoor heat exchanger 4.

[0014] The refrigerant flowing through the refrigerant circuit of the air conditioning device 1 may be, for example, a flammable refrigerant. The flammable refrigerant may be, for example, a flammable refrigerant such as propane, a low flammable refrigerant, or a slightly flammable refrigerant.

[0015] The outdoor heat exchanger 3 is a heat source device located, for example, outdoors. The outdoor heat exchanger 3 exchanges heat between outdoor air and the refrigerant. A fan 8 for drawing air is provided near the outdoor heat exchanger 3. The indoor heat exchanger 4 is located, for example, in the air-conditioned space R1. The indoor heat exchanger 4 exchanges heat between indoor air and the refrigerant.

[0016] The four-way valve 5 switches the refrigerant circulation order between a first order and a second order. In the first order, the refrigerant circulates through the compressor 2, the outdoor heat exchanger 3, the expansion valve 6, the indoor heat exchanger 4, and the compressor 2 in that order. In the second order, the refrigerant circulates through the compressor 2, the indoor heat exchanger 4, the expansion valve 6, the outdoor heat exchanger 3, and the compressor 2 in that order.

[0017] The air conditioning apparatus 1 further includes shutoff devices 21, 22 that change between a first state for allowing refrigerant to circulate and a second state for preventing refrigerant leakage. The shutoff devices 21, 22 are disposed in the refrigerant circuit. The shutoff device 21 is provided on the port P1 side of the indoor heat exchanger 4. In other words, the shutoff device 21 is provided on the refrigerant piping 51. The shutoff device 22 is provided on the port P2 side of the indoor heat exchanger 4. In other words, the shutoff device 21 is provided on the refrigerant piping 52.

[0018] The shutoff device 21 includes a solenoid valve 210. The shutoff device 21 is arranged outside the indoor unit 20. The shutoff device 22 includes expansion valves 221, 222. The expansion valves 221 and 222 are connected in series. The expansion valves 221, 222 are, for example, linear expansion valves (LEV). The expansion valve 221 is arranged in the indoor unit 20. The expansion valve 222 is arranged outside the indoor unit 20. In the following, this embodiment will be described assuming that the expansion valves 221, 222 are configured as linear expansion valves (LEV).

[0019] The solenoid valve 210 may be disposed in the indoor unit 20. In other words, the shutoff device 21 may be disposed in the indoor unit 20. Furthermore, the shutoff device 21 may be disposed outside the air-conditioned space R1, for example, in the attic where conditioned air is not expected to be sent.

[0020] The expansion valves 221, 222 may be arranged in the indoor unit 20. In other words, the shutoff device 22 may be arranged in the indoor unit 20. The expansion valves 221, 222 may be arranged outside the indoor unit 20. In other words, the shutoff device 22 may be arranged outside the indoor unit 20. Furthermore, the shutoff device 22 may be arranged outside the air-conditioned space R1, for example, in the attic where it is not expected that conditioned air will be sent.

[0021] The outdoor unit 10 further includes a control device 100 that controls the air conditioning apparatus 1. The control device 100 controls the compressor 2, the four-way valve 5, the expansion valve 6, and the shut-off devices 21 and 22. The control device 100 may be disposed in the indoor unit 20. The control device 100 may also be disposed in a location separate from the outdoor unit 10 and the indoor unit 20.

[0022] The compressor 2 starts and stops operation under the control of the control device 100. The compressor 2 changes its operation frequency under the control of the control device 100. The amount of refrigerant discharged from the compressor 2 changes in response to the change in the operation frequency.

[0023] The expansion valve 6 is configured by, for example, a linear expansion valve. The expansion valve 6 reduces the pressure of the refrigerant that has flowed in and causes the decompressed refrigerant to flow out. The control device 100 adjusts the opening degree of the expansion valve 6 to adjust the amount of decompression of the refrigerant.

[0024] The control device 100 switches the operation mode between a cooling operation mode for cooling the room and a heating operation mode for heating the room. When the cooling operation is performed, the outdoor heat exchanger 3 functions as a condenser, and the indoor heat exchanger 4 functions as an evaporator. When the heating operation is performed, the outdoor heat exchanger 3 functions as an evaporator, and the indoor heat exchanger 4 functions as a condenser.

[0025] (Heating Operation) Heating operation will now be described. The arrows in FIG. 1 indicate the direction in which the refrigerant flows during heating operation. The high-temperature, high-pressure gas refrigerant discharged from the compressor 2 flows into the indoor heat exchanger 4 via the four-way valve 5. The indoor heat exchanger 4 functions as a condenser. The indoor heat exchanger 4 exchanges heat between the high-temperature, high-pressure gas refrigerant and the indoor air. This heats the room. The gas refrigerant condenses inside the indoor heat exchanger 4 and changes into liquid refrigerant. The liquid refrigerant obtained by the indoor heat exchanger 4 flows toward the expansion valve 6.

[0026] The liquid refrigerant that flows into the expansion valve 6 is decompressed and changes into a low-pressure two-phase gas-liquid refrigerant. The refrigerant that passes through the expansion valve 6 flows into the outdoor heat exchanger 3. The outdoor heat exchanger 3 functions as an evaporator. The outdoor heat exchanger 3 exchanges heat between the low-pressure two-phase gas-liquid refrigerant and the outdoor air. The two-phase gas-liquid refrigerant that absorbs heat from the outdoor air evaporates inside the outdoor heat exchanger 3 and changes into a gas refrigerant. The gas refrigerant obtained by the outdoor heat exchanger 3 flows into the accumulator 7 via the four-way valve 5. The refrigerant is separated into gas and liquid in the accumulator 7. As a result, the gas refrigerant is sent from the accumulator 7 to the compressor 2.

[0027] (Cooling Operation) Cooling operation will now be described. During cooling operation, the compressor 2 draws in low-temperature, low-pressure gas refrigerant from the indoor heat exchanger 4 and compresses the drawn gas refrigerant to increase the pressure of the gas refrigerant. The compressor 2 discharges the high-temperature, high-pressure gas refrigerant obtained by compression. The discharged gas refrigerant flows into the outdoor heat exchanger 3 via the four-way valve 5. The outdoor heat exchanger 3 functions as a condenser. The outdoor heat exchanger 3 exchanges heat between the high-temperature, high-pressure gas refrigerant and the outdoor air. The gas refrigerant condenses inside the outdoor heat exchanger 3 and changes into liquid refrigerant.

[0028] The liquid refrigerant obtained by the outdoor heat exchanger 3 flows to the expansion valve 6. The liquid refrigerant that flows into the expansion valve 6 is decompressed and changes into low-pressure gas-liquid two-phase refrigerant. The refrigerant that passes through the expansion valve 6 flows into the indoor heat exchanger 4. The indoor heat exchanger 4 functions as an evaporator. The indoor heat exchanger 4 exchanges heat between the low-pressure gas-liquid two-phase refrigerant and the indoor air. This cools the room. The gas-liquid two-phase refrigerant that absorbs heat from the indoor air evaporates inside the indoor heat exchanger 4 and changes into gas refrigerant. The gas refrigerant obtained by the indoor heat exchanger 4 flows into the suction port of the compressor 2 via the four-way valve 5 and the accumulator 7.

[0029] (Detection of refrigerant leak) The indoor unit 20 further includes a control device 200 that communicates with the control device 100, and a refrigerant sensor 25 that detects refrigerant leaks. The refrigerant sensor 25 may be located outside the indoor unit 20. However, it is preferable that the refrigerant sensor 25 be located in the air-conditioned space R1. The control device 200 transmits the detection value of the refrigerant sensor 25 to the control device 100. The control device 100 detects refrigerant leaks based on the detection value of the refrigerant sensor.

[0030] If the control device 100 does not detect a refrigerant leak, it sets the state of each of the shutoff devices 21 and 22 to a first state for allowing the refrigerant to flow. More specifically, if the control device 100 does not detect a refrigerant leak, it sends a command signal to the shutoff device 21 to fully open the solenoid valve 210, and sends a command signal to the shutoff device 22 to fully open the expansion valves 221 and 222. This sets each of the shutoff devices 21 and 22 to the first state. As a result, the refrigerant flows through the refrigerant pipes 51 and 52.

[0031] For example, in the heating operation mode, the refrigerant flowing from the four-way valve 5 to the refrigerant pipe 51 flows into the indoor heat exchanger 4, and the refrigerant flowing out from the indoor heat exchanger 4 flows from the refrigerant pipe 52 to the expansion valve 6 of the outdoor unit 10. In the cooling operation mode, the refrigerant flowing from the expansion valve 6 of the outdoor unit 10 to the refrigerant pipe 52 flows into the indoor heat exchanger 4, and the refrigerant flowing out from the indoor heat exchanger 4 flows from the refrigerant pipe 51 to the four-way valve 5.

[0032] When the control device 100 detects a refrigerant leak, it changes the state of each of the shutoff devices 21 and 22 from a first state that allows refrigerant to flow to a second state that prevents refrigerant leakage. More specifically, when the control device 100 detects a refrigerant leak, it sends a command signal to the shutoff device 21 to fully close the solenoid valve 210, and sends a command signal to the shutoff device 22 to fully close the expansion valves 221 and 222. This sets each of the shutoff devices 21 and 22 to the second state. As a result, refrigerant leakage in the air-conditioned space R1 is prevented.

[0033] (Relationship Between Opening Degree of Expansion Valves 221, 222 and Refrigerant Flow Rate) FIG. 2 is a graph showing the relationship between the opening degree and refrigerant flow rate of the expansion valves 221, 222 used in the shutoff device 22. If the refrigerant flow rate at "opening degree = 100%" is 100%, the refrigerant flow rate at "opening degree = 0%" is not 0%. Therefore, when the expansion valves 221, 222 receive a fully closed command from the control device 100, they operate to fully close with a precision that does not completely shut off the flow of refrigerant. In other words, when the expansion valves 221, 222 receive a fully closed command from the control device 100, they operate to close in an incompletely shutoff state that does not completely shut off the flow of refrigerant. Therefore, when each of the expansion valves 221, 222 is in an "opening degree = zero" state (fully closed), a small gap is created in each of the expansion valves 221, 222 through which a very small amount of refrigerant can pass.

[0034] An expansion valve that fully closes with an accuracy that does not completely shut off the flow of refrigerant when a fully close command is received from the control device 100 is generally less expensive than an expansion valve that fully closes with an accuracy that can completely shut off the flow of refrigerant when a fully close command is received from the control device 100. In the present disclosure, the shutoff device 22 is configured using such a relatively inexpensive expansion valve.

[0035] In addition, in order to make it easier to understand that the refrigerant flow rate does not become zero when the opening degree of the expansion valves 221, 222 is zero, the refrigerant flow rate corresponding to "opening degree = 0%" is represented in the graph shown in Figure 3 as being higher than the actual flow rate.

[0036] 3 is a conceptual diagram showing the amount of refrigerant passing through when the shutoff devices 21 and 22 are fully closed. When the solenoid valve 210 in the shutoff device 21 is fully closed, the flow of refrigerant is completely blocked by the solenoid valve 210. Therefore, the amount of refrigerant passing through the shutoff device 21 when the shutoff device 21 is fully closed is zero.

[0037] When the expansion valves 221 and 222 in the shutoff device 22 are fully closed, the gaps between the expansion valves 221 and 222 form refrigerant flow paths through which a very small amount of refrigerant can flow.

[0038] Therefore, when the shutoff devices 21, 22 are fully closed, the refrigerant present between the shutoff devices 21 and 22 is not completely sealed. This prevents a so-called liquid-sealed state from occurring between the shutoff devices 21 and 22. As a result, it is possible to prevent damage to the refrigerant circuit including the refrigerant pipe and the indoor heat exchanger 4, which would otherwise occur if the pressure in the refrigerant pipe in which the refrigerant is sealed increases due to a rise in temperature. In other words, in this embodiment, a liquid-sealing prevention circuit is realized by connecting the relatively inexpensive expansion valves 221, 222 in series.

[0039] In this embodiment, a liquid seal prevention circuit is realized by connecting multiple expansion valves in series, but it is also possible to realize a liquid seal prevention circuit with a single expansion valve. However, with a single expansion valve, there is only one "wall" to block the refrigerant flow when the valve is fully closed, and the flow of refrigerant cannot be sufficiently suppressed. In this embodiment, multiple expansion valves (linear expansion valves) are connected in series, forming multiple "walls" to block the refrigerant flow when the valve is fully closed, thereby achieving sufficient resistance to the refrigerant flow.

[0040] The linear expansion valve employed in this embodiment does not completely shut off the refrigerant when fully closed, but allows a small amount of refrigerant to flow. By connecting multiple linear expansion valves in series, the amount of refrigerant passing through the linear expansion valve can be gradually reduced. This allows for the creation of a liquid seal state with an inexpensive configuration while allowing for refrigerant leakage that does not affect the environment of the room (air-conditioned space). This embodiment makes it possible to prevent a liquid seal state while preventing refrigerant leakage that would have a significant impact on the air-conditioned space.

[0041] As shown in FIG. 3 , the refrigerant flow rate corresponding to the fully closed state (opening degree = 0%) is smaller for the expansion valve 222 than for the expansion valve 221. In other words, the refrigerant flow path created in the expansion valve when the opening degree is 0% is narrower for the expansion valve 222 than for the expansion valve 221. Therefore, the expansion valve 222 blocks the flow of refrigerant more accurately than the expansion valve 221. In other words, the second expansion valve 222 blocks the flow of refrigerant less in an incompletely blocked state than the first expansion valve 221. As shown in FIG. 1 , in the path through which refrigerant circulates between the outdoor unit 10 and the indoor unit 20, the expansion valve 222 is positioned closer to the outdoor unit 10 than the expansion valve 221. Therefore, when refrigerant flows from the outdoor unit 10 into the indoor unit 20 via the refrigerant piping 52, the expansion valve 222 can block the source of the refrigerant with high accuracy.

[0042] (Explanation of Block Diagram) FIG. 4 is a block diagram showing the configuration of the control device 100 arranged in the outdoor unit 10, the control device 200 arranged in the indoor unit 20, the shutoff devices 21 and 22, and the remote control 30.

[0043] The control device 100 includes a processor 101, a memory 102, and a communication interface 103. The processor 101 is a computing entity that executes various programs. The processor 101 communicates with various devices included in the air conditioning apparatus 1 via the communication interface 103.

[0044] The processor is configured, for example, by a microcontroller, a central processing unit (CPU), or a micro-processing unit (MPU). The processor 101 has the function of executing 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).

[0045] The processor 101 is not limited to a processor in the narrow sense that executes processing using a stored program, such as a CPU or MPU, but may also include hardwired circuits such as an ASIC or FPGA. Therefore, the processor 101 can also be interpreted as processing circuitry, whose processing is predefined by computer-readable code and / or hardwired circuits. The processor 101 may be configured on a single chip or multiple chips. Furthermore, the processor 101 and associated processing circuits may be configured on multiple computers interconnected by wire or wirelessly via a local area network or a wireless network. The processor 101 and associated processing circuits may also 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 distant location.

[0046] The memory 102 provides a storage area for storing program code, various variables, and the like when the processor 101 executes various programs. The memory 102 may be one or more non-transitory computer-readable media. Examples of the memory 102 include volatile memory such as dynamic random access memory (DRAM) and static random access memory (SRAM), and non-volatile memory such as read-only memory (ROM) and flash memory. The memory 102 may also be one or more computer-readable storage media. Examples of the memory 102 include storage devices such as hard disk drives (HDDs) and solid-state drives (SSDs). The processor 101 executes various controls by executing the programs stored in the memory 102.

[0047] The control device 200 includes a processor 201, a memory 202, and a communication interface 203. These components of the control device 200 are equivalent to the components of the control device 100, and therefore will not be described repeatedly here. The control devices 100 and 200 communicate with each other via communication interfaces 103 and 203. The remote control 30 communicates with the indoor unit 20 and issues commands to the indoor unit 20 regarding the operation mode, room temperature, humidity, and the like. The remote control 30 includes a display 31.

[0048] The control device 100 acquires a detection signal from the refrigerant sensor 25 via the control device 200. The control device 100 transmits a command signal for fully closing or fully closing to the shutoff devices 21, 22 via the control device 200. The control device 100 may transmit a command signal for fully closing or fully closing to the shutoff devices 21, 22 without via the control device 200. The control device 200 outputs a control signal to the control device 100 in response to a command received from the remote control 30. The control device 100 displays necessary information on the display 31 of the remote control 30 via the control device 200. (Processing Procedure Executed When a Refrigerant Leak is Detected) FIG. 5 is a flowchart showing the processing procedure executed by the control device 100 when a refrigerant leak is detected. First, the control device 100 determines whether a refrigerant leak has been detected based on the detection value of the refrigerant sensor 25 (step S1). If a refrigerant leak has not been detected, the control device 100 ends the processing based on this flowchart.

[0049] If a refrigerant leak is detected, the control device 100 stops operation of the compressor 2 (step S2). Next, the control device 100 closes the solenoid valve 210 and the expansion valve 222 (step S3). This sets the shutoff device 21 to the second state, and one of the two expansion valves included in the shutoff device 22 is fully closed. Next, the control device 100 closes the expansion valve 221 (step S4). This sets the shutoff device 22 to the second state.

[0050] In this flowchart, of the two expansion valves included in the shutoff device 22, the expansion valve 222 fully closes before the expansion valve 221. The expansion valve 222 is disposed closer to the outdoor unit 10 than the expansion valve 221. Therefore, when the refrigerant flows from the outdoor unit 10 into the indoor unit 20 via the refrigerant piping 52, the expansion valve 222 can quickly shut off the refrigerant's inflow source. Moreover, the expansion valve 222 can shut off the refrigerant flow more accurately than the expansion valve 221. Therefore, when the refrigerant flows from the outdoor unit 10 into the indoor unit 20 via the refrigerant piping 52, the expansion valve 222 can quickly and accurately shut off the refrigerant's inflow source. (Processing Procedure for Identifying the Location of a Refrigerant Leak) FIG. 6 is a flowchart showing the processing procedure executed by the control device 100 to identify the location of a refrigerant leak. The control device 100 executes the processing procedure described below to determine whether the refrigerant leak is between the expansion valves 221 and 222, or between the expansion valve 221 and the solenoid valve 210 (shutoff device 21). Note that when this flowchart is executed, the solenoid valve 210 and the expansion valves 221 and 222 are assumed to be fully closed to prevent refrigerant leakage.

[0051] First, the control device 100 determines whether or not to start control to identify the leak location (step S11). If the control device 100 does not start control to identify the leak location, it ends the processing based on this flowchart. If the control device 100 does start control to identify the leak location, it opens the expansion valve 222 (step S12). Next, the control device 100 determines whether the refrigerant concentration is lower than threshold A (step S13).

[0052] The threshold value A is a refrigerant concentration required to determine whether a refrigerant leak has occurred in the air-conditioned space R1. In this embodiment, when the shutoff device 22 shuts off the refrigerant circuit, a very small amount of refrigerant may leak from the refrigerant circuit to prevent liquid sealing, but the amount does not affect the environment of the air-conditioned space R1. In this embodiment, the threshold value A is set to determine whether a refrigerant leak has occurred that is large enough to be determined to affect the environment of the air-conditioned space R1.

[0053] If the control device 100 determines in step S13 that the refrigerant concentration is not lower than threshold A, it determines that the leakage location is between expansion valve 221 and expansion valve 222 (step S17). Next, the control device 100 outputs the determination result to the remote control 30 (step S19). The determination result is displayed on the remote control 30.

[0054] If the control device 100 determines in step S13 that the refrigerant concentration is lower than threshold value A, it opens the expansion valve 221 (step S14). Next, the control device 100 determines whether the refrigerant concentration is lower than threshold value A (step S15). If the control device 100 determines in step S15 that the refrigerant concentration is not lower than threshold value A, it determines that the leakage location is between the expansion valve 221 and the solenoid valve 210 (shutoff device 21) (step S18). Next, the control device 100 outputs the determination result to the remote control 30 (step S19). The determination result is displayed on the remote control 30.

[0055] If the control device 100 determines in step S15 that the refrigerant concentration is lower than threshold A, it closes the expansion valves 221 and 222 (step S16) and ends the processing based on this flowchart. In this way, according to this processing procedure, it is possible to identify the location of the refrigerant leak.

[0056] As described above, according to this embodiment, when a refrigerant leak is detected, the refrigerant leak can be suppressed with a relatively inexpensive configuration without causing a liquid seal state. Note that the number of expansion valves is not limited to two, 221 and 222, and the shutoff device 22 may be configured by connecting three or more expansion valves in series.

[0057] Embodiment 2 Next, embodiment 2 will be described with reference to Fig. 7. Fig. 7 is a diagram showing the configuration of an air conditioning apparatus 1A according to embodiment 2. Air conditioning apparatus 1A differs from air conditioning apparatus 1 in that it employs a shutoff device 22A instead of shutoff device 22, but otherwise has the same configuration as air conditioning apparatus 1.

[0058] 7 , shutoff device 22A differs from shutoff device 22 in that solenoid valve 223 is connected in parallel to expansion valve 222, but otherwise has a similar configuration to shutoff device 22. When no refrigerant leakage is detected, control device 100 fully opens solenoid valve 210, expansion valves 221 and 222, and solenoid valve 223. When a refrigerant leakage is detected, control device 100 fully closes solenoid valve 210, expansion valves 221 and 222, and solenoid valve 223. Instead of connecting solenoid valve 223 in parallel to expansion valve 222, solenoid valve 223 may be connected in parallel to expansion valve 221. Solenoid valve 223 may be connected in parallel to each of expansion valves 221 and 222.

[0059] Embodiment 3 Next, embodiment 3 will be described with reference to Fig. 8. Fig. 8 is a diagram showing the configuration of an air conditioning apparatus 1B according to embodiment 3. Air conditioning apparatus 1B differs from air conditioning apparatus 1 in that it employs a shutoff device 21B instead of shutoff device 21, but otherwise has the same configuration as air conditioning apparatus 1.

[0060] As shown in Fig. 8, the shutoff device 21B is configured with expansion valves 211 and 212 connected in series instead of the solenoid valve 210. The expansion valves 211 and 212 are, for example, relatively inexpensive expansion valves that have the characteristics shown in Fig. 2 similar to the expansion valves 211 and 212. When no refrigerant leak is detected, the control device 100 fully opens the expansion valves 211, 212, 221, and 222. When a refrigerant leak is detected, the control device 100 fully closes the expansion valves 211, 212, 221, and 222.

[0061] According to the third embodiment, by using inexpensive expansion valves instead of expensive solenoid valves that can completely prevent refrigerant leakage, product costs can be further reduced. The expansion valves 211 and 212 may have higher closing performance than the expansion valves 221 and 222. For example, the expansion valves 211 and 212 may be expansion valves that fully close with sufficient precision to completely block the flow of refrigerant when a fully closing command is received from the control device 100. Furthermore, the solenoid valve 223 may be connected in parallel to one or more of the expansion valves 211, 212, 221, and 222, as in the second embodiment.

[0062] Embodiment 4 Next, embodiment 4 will be described with reference to Fig. 9. Fig. 9 is a diagram showing the configuration of an air conditioning apparatus 1C according to embodiment 4. The air conditioning apparatus 1C differs from the air conditioning apparatus 1 in that it further comprises a configuration corresponding to an indoor unit 20 arranged in the air-conditioned space R2, but otherwise comprises the same configuration as the air conditioning apparatus 1.

[0063] As shown in Figure 9, the configuration arranged in air-conditioned space R2 is the same as the configuration arranged in air-conditioned space R1. The indoor unit 20 arranged in air-conditioned space R1 and the indoor unit 20 arranged in air-conditioned space R2 are connected in parallel to refrigerant pipes 51, 52 together with shutoff devices 21, 22. Note that although two air-conditioned spaces are shown here as an example of multiple air-conditioned spaces, the air conditioner 1C may have a configuration for three or more air-conditioned spaces. In at least one of the air-conditioned spaces R1, R2 in embodiment 4, the solenoid valve 223 according to embodiment 2 may be employed, or the expansion valves 211, 212 according to embodiment 3 may be employed.

[0064] The above embodiments will be summarized. (Item 1) The present disclosure relates to an air conditioning apparatus (1, 1A to 1C) including an outdoor unit (10) having an outdoor heat exchanger (3), an indoor unit (20) having an indoor heat exchanger (4) and blowing conditioned air into an air-conditioned space, a refrigerant sensor (25) disposed in the air-conditioned space and detecting a refrigerant leak, a shutoff device (21, 21B, 22, 22A) that changes between a first state for circulating the refrigerant and a second state for preventing the refrigerant leak, and a control device (100), wherein the indoor heat exchanger (4) is connected to a first refrigerant pipe (51) and a second refrigerant pipe (52) for circulating the refrigerant between the outdoor heat exchanger (3) and the indoor heat exchanger (4), and the shutoff device (21, 21B, 22, 22A) is connected to a first shutoff device (21, 21B, 22, 22A) provided in the first refrigerant pipe (51). The control device (100) controls each of the first shutoff device (21) and the second shutoff device (22) provided on the second refrigerant pipe (52) when a refrigerant leak is detected by the refrigerant sensor (25), and the control device (100) controls each of the first shutoff device (21, 21B) and the second shutoff device (22, 22A) to a second state, and the second shutoff device (22, 22A) includes a first expansion valve (221) and a second expansion valve (222) connected in series, and each of the first expansion valve (221) and the second expansion valve (222) operates to close in an incomplete shutoff state in which the flow of refrigerant cannot be completely shut off when a command to fully close is received from the control device (100), and the second state includes the incomplete shutoff state of each of the first expansion valve (221) and the second expansion valve (222).

[0065] (2) In the air conditioning apparatus (1, 1A, 1C) described in 1, the first shutoff device (21) includes a first solenoid valve (210), and the second state of the first shutoff device (21) is a state in which the first solenoid valve (210) is fully closed.

[0066] (3) In the air conditioning apparatus (1A) described in paragraph 1 or paragraph 2, the second shutoff device (22A) includes a second solenoid valve (223) connected in parallel to one of the first expansion valve (221) and the second expansion valve (222), and in the second state of the second shutoff device, the second solenoid valve (223) is fully closed.

[0067] (4) In the air conditioning apparatus (1B) described in paragraph 1, the first shutoff device (21B) includes a plurality of expansion valves (211, 212) connected in series, and the second state of the first shutoff device (21B) is a state in which each of the plurality of expansion valves (211, 212) is fully closed.

[0068] (Item 5) In the air conditioning apparatus (1, 1A to 1C) described in any one of Items 1 to 4, in the path in which the refrigerant circulates between the outdoor unit (10) and the indoor unit (20), the second expansion valve (222) is positioned closer to the outdoor unit (10) than the first expansion valve (221), and the second expansion valve (222) has a smaller amount of refrigerant circulating in an incomplete shutoff state than the first expansion valve.

[0069] (6) In the air conditioning device (1, 1A to 1C) described in any one of paragraphs 1 to 4, in the path in which the refrigerant circulates between the outdoor unit (10) and the indoor unit (20), the second expansion valve (222) is arranged at a position closer to the outdoor unit (10) than the first expansion valve (221), and when a refrigerant leak is detected by the refrigerant sensor (25), the control device (100) outputs a command to fully close the second expansion valve (222) so that the second expansion valve (222) closes before the first expansion valve (221) (steps S3 and S4).

[0070] (7) In the air conditioner (1, 1A to 1C) described in any one of paragraphs 1 to 4, in a path in which a refrigerant circulates between the outdoor unit (10) and the indoor unit (20), the second expansion valve (222) is arranged at a position closer to the outdoor unit (10) than the first expansion valve (221), and the control device (100) controls each of the first shutoff device (21, 21B) and the second shutoff device (22, 22A) to a second state, and then executes a first determination process and a second determination process to identify a location of a refrigerant leak, and in the first determination process, the control device (100) determines whether the refrigerant leaks when the second expansion valve (222) is opened while the first shutoff device (21, 21B) is maintained in the second state. If the sensor (25) detects a refrigerant leak, it is determined that a refrigerant leak has occurred between the first expansion valve (221) and the second expansion valve (222) (steps S12, S13, and S17). If the refrigerant leak is not detected by the refrigerant sensor (25) in the first determination process, the control device (100) determines in the second determination process that a refrigerant leak has occurred between the first expansion valve (221) and the first shut-off device (21) if the refrigerant sensor (25) detects a refrigerant leak when the first expansion valve (221) is opened while maintaining the second state of the first shut-off device (21, 21B) (steps S14, S15, and S18).

[0071] 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.

[0072] 1, 1A, 1B, 1C air conditioning device, 2 compressor, 3 outdoor heat exchanger, 4 indoor heat exchanger, 5 four-way valve, 6, 211, 212, 221, 222 expansion valve, 8 fan, 10 outdoor unit, 20 indoor unit, 21, 21B, 22, 22A shutoff device, 25 refrigerant sensor, 30 remote control, 31 display, 51, 52 refrigerant piping, 100, 200 control device, 101, 201 processor, 102, 202 memory, 103, 203 communication interface, 210 solenoid valve, P1, P2 port, R1, R2 air-conditioned space.

Claims

1. An air conditioning device, an outdoor unit having an outdoor heat exchanger; an indoor unit having an indoor heat exchanger and blowing conditioned air into the air-conditioned space; a refrigerant sensor disposed in the air-conditioned space and configured to detect refrigerant leakage; a shutoff device that changes between a first state for allowing the refrigerant to flow and a second state for preventing the refrigerant from leaking; a control device; the indoor heat exchanger is connected to a first refrigerant pipe and a second refrigerant pipe for circulating a refrigerant between the outdoor heat exchanger and the indoor heat exchanger; The shutoff device is a first shutoff device provided in the first refrigerant pipe; a second shutoff device provided on the second refrigerant pipe, the control device controls each of the first shutoff device and the second shutoff device to the second state when the refrigerant leak is detected by the refrigerant sensor; the second shutoff device includes a first expansion valve and a second expansion valve connected in series; each of the first expansion valve and the second expansion valve operates to close in an incompletely shut-off state in which the flow of refrigerant cannot be completely shut off when a fully closed command is received from the control device; The air conditioner, wherein the second state includes the incomplete shutoff state of each of the first expansion valve and the second expansion valve.

2. the first shutoff device includes a first solenoid valve; The air conditioner according to claim 1 , wherein the second state of the first shutoff device is a state in which the first solenoid valve is fully closed.

3. the second shutoff device includes a second solenoid valve connected in parallel to one of the first expansion valve and the second expansion valve, 3. The air conditioning apparatus according to claim 1, wherein in the second state of the second shutoff device, the second solenoid valve is fully closed.

4. the first shutoff device includes a plurality of expansion valves connected in series; The air conditioner according to claim 1 , wherein the second state of the first shutoff device is a state in which each of the plurality of expansion valves is fully closed.

5. In a path through which a refrigerant circulates between the outdoor unit and the indoor unit, the second expansion valve is disposed closer to the outdoor unit than the first expansion valve, The air conditioner according to claim 1 or 2, wherein the second expansion valve has a smaller amount of refrigerant flowing through it in the incomplete shutoff state than the first expansion valve.

6. In a path through which a refrigerant circulates between the outdoor unit and the indoor unit, the second expansion valve is disposed closer to the outdoor unit than the first expansion valve, 3. The air conditioning apparatus according to claim 1, wherein the control device outputs the full closure command so that the second expansion valve closes before the first expansion valve when a refrigerant leak is detected by the refrigerant sensor.

7. In a path through which a refrigerant circulates between the outdoor unit and the indoor unit, the second expansion valve is disposed closer to the outdoor unit than the first expansion valve, the control device controls each of the first shutoff device and the second shutoff device to the second state, and then executes a first determination process and a second determination process to identify a location of a refrigerant leak; In the first determination process, if a refrigerant leak is detected by the refrigerant sensor when the second expansion valve is opened with the first shutoff device maintained in the second state, the control device determines that a refrigerant leak has occurred between the first expansion valve and the second expansion valve, An air conditioning apparatus as described in claim 1 or claim 2, wherein if the refrigerant sensor does not detect a refrigerant leak in the first determination process, in the second determination process, the control device determines that a refrigerant leak has occurred between the first expansion valve and the first shut-off device if the refrigerant sensor detects a refrigerant leak when the first expansion valve is opened while the first shut-off device is maintained in the second state.