Refrigeration cycle device, control method, and program

Abstract

The present invention provides a refrigeration cycle device that prevents refrigerant recovered in the heat source side's refrigerant circuit from leaking into the utilization side's refrigerant circuit through a closed valve. [Solution] The refrigeration cycle device includes a refrigerant circuit (10) including a heat source side circuit (20a) and a utilization side circuit (40a), a utilization unit (40) for air conditioning the target space (S), a refrigerant leak sensor (70) for detecting refrigerant leaks in the utilization side circuit (40a), and a first shut-off valve that, when the refrigerant leak sensor (70) detects a refrigerant leak, shuts off the flow of refrigerant from one end of the heat source side circuit (20a) to the utilization side circuit (40a). The system includes (43), a second shut-off valve (26) that shuts off the flow of refrigerant from the other end of the heat source side circuit (20a) to the utilization side circuit (40a), and a control unit (100) that performs a first recovery operation to recover refrigerant to the heat source side circuit (20a) when the refrigerant circuit (10) is shut off by the first shut-off valve (43) and the second shut-off valve (26) and a first condition regarding refrigerant leakage to the utilization side circuit (40a) is met.

Description

Technical Field

[0001] The present disclosure relates to a refrigeration cycle device, a control method, and a program.

Background Art

[0002] Patent Document 1 discloses a refrigeration system that, when refrigerant leakage is detected from a certain utilization unit among a plurality of utilization units, stops the use of the utilization unit and executes refrigerant recovery control to recover the refrigerant from the utilization unit targeted for suspension to the heat source unit. In the refrigerant recovery control, the compressor is temporarily operated with the heat source side expansion valve closed, so that the refrigerant existing in the utilization unit targeted for suspension is recovered to the heat source unit.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, after the refrigerant recovery control as in Patent Document 1, there is a possibility that the refrigerant in the refrigerant circuit recovered on the heat source side leaks (flows in) into the refrigerant circuit on the utilization side through the closed valve.

[0005] An object of the present disclosure is to suppress the refrigerant recovered in the refrigerant circuit on the heat source side from leaking into the refrigerant circuit on the utilization side through the closed valve.

Means for Solving the Problems

[0006] The first aspect is a refrigerant circuit (10) including a heat source side circuit (20a) to which a compressor (22) and a heat source side heat exchanger (23) are connected, and a utilization side circuit (40a) to which a utilization side heat exchanger (42) is connected, and A utilization unit (40) having the aforementioned utilization-side heat exchanger (42) and air conditioning the target space (S), A refrigerant leak sensor (70) for detecting refrigerant leaks in the user-side circuit (40a), When the refrigerant leak sensor (70) detects a refrigerant leak, a first shut-off valve (43) is activated to block the flow of refrigerant from one end of the heat source side circuit (20a) to the utilization side circuit (40a), A second shut-off valve (26) that blocks the flow of refrigerant from the other end of the heat source side circuit (20a) toward the utilization side circuit (40a), The system includes a control unit (100) that, when the refrigerant circuit (10) is shut off by the first shut-off valve (43) and the second shut-off valve (26), executes a first recovery operation to recover refrigerant to the heat source side circuit (20a) when a first condition regarding refrigerant leakage from the heat source side circuit (20a) to the utilization side circuit (40a) is met. It is a refrigeration cycle device.

[0007] In the first embodiment, the first recovery operation suppresses the inflow of refrigerant into the user-side circuit (40a) and allows the refrigerant to be recovered into the heat source-side circuit (20a).

[0008] A second aspect is, in the first aspect, The first condition described above is met when a rise in low pressure is detected.

[0009] In the second embodiment, it can be seen that refrigerant is leaking into the user-side circuit (40a) due to the rise in low pressure, and this can be considered the first condition.

[0010] A third aspect is, in the second aspect, The refrigerant circuit (10) is further equipped with a first pressure sensor (62) that detects low pressure, The first pressure sensor (62) is located on the user-side circuit (40a) side of the second shut-off valve (26), or in the suction line of the compressor (22).

[0011] In the third embodiment, by detecting an increase in the value detected by the first pressure sensor (62), it is possible to determine that the amount of refrigerant leaking from the heat source circuit (20a) (closed circuit) to the user-side circuit (40a) exceeds the amount of refrigerant leaking from the user-side circuit (40a).

[0012] The fourth aspect is one of the first to third aspects, The second shut-off valve (26) includes a check valve that restricts the flow of refrigerant from the heat source side circuit (20a) to the utilization side circuit (40a).

[0013] In the fourth embodiment, refrigerant leakage from the heat source side circuit (20a) to the utilization side circuit (40a) can be detected via a second shut-off valve (26), which is a check valve.

[0014] A fifth aspect is a second or third aspect, The control unit (100) In the first recovery operation, the first recovery operation is stopped when the second condition is met, which is that the low pressure is below a predetermined value.

[0015] In the fifth embodiment, the fulfillment of the second condition indicates that there is no refrigerant leakage from the heat source circuit (20a) to the utilization circuit (40a). In other words, the recovery operation can be stopped after the fulfillment of the second condition.

[0016] The sixth aspect is one of the first to third aspects, The control unit (100) After performing a second recovery operation to recover refrigerant from the user-side circuit (40a) to the heat source-side circuit (20a), if the first condition is met, the first recovery operation is performed.

[0017] In the sixth embodiment, after the second recovery operation (so-called pump-down operation) is completed, leakage of refrigerant from the heat source side circuit (20a) to the utilization side circuit (40a) can be suppressed.

[0018] The seventh aspect is as described in the sixth aspect. The second recovery operation is an operation in which the compressor (22) is driven with the first shut-off valve (43) closed when the refrigerant leak sensor (70) detects a refrigerant leak.

[0019] In the seventh aspect, the refrigerant can be recovered into the heat source side circuit (20a) by the second recovery operation, and the refrigerant leak from the utilization side circuit (40a) can be suppressed. The second recovery operation is a so-called pump-down operation.

[0020] The eighth aspect is in the sixth aspect, the second shut-off valve (26) is an on-off valve (26), after the control unit (100) executes the second recovery operation, the control unit closes the on-off valve (26).

[0021] In the eighth aspect, by closing the on-off valve (26) after the second recovery operation, the flow of the refrigerant from the heat source side circuit (20a) to the utilization side circuit (40a) can be blocked.

[0022] The ninth aspect is in the eighth aspect, when the first condition is satisfied, the control unit (100) executes the first recovery operation by opening the on-off valve (26).

[0023] In the ninth aspect, by opening the on-off valve (26), the refrigerant remaining on the utilization side circuit (40a) side can be recovered into the heat source side circuit (20a).

[0024] The tenth aspect is in any one of the first to third aspects, the first shut-off valve (43) is provided in the utilization side circuit (40a).

[0025] In the tenth aspect, the first shut-off valve (43) is a shut-off valve provided in the utilization unit (40).

[0026] The eleventh aspect is in any one of the first to third aspects, the second shut-off valve (26) is provided in the heat source side circuit (20a).

[0027] The twelfth aspect is, A refrigerant circuit (10) includes a heat source side circuit (20a) to which a compressor (22) and a heat source side heat exchanger (23) are connected, and a utilization side circuit (40a) to which a utilization side heat exchanger (42) is connected, A utilization unit (40) having the aforementioned utilization-side heat exchanger (42) and air conditioning the target space (S), A refrigerant leak sensor (70) for detecting refrigerant leaks in the user-side circuit (40a), When the refrigerant leak sensor (70) detects a refrigerant leak, a first shut-off valve (43) is activated to block the flow of refrigerant from one end of the heat source side circuit (20a) to the utilization side circuit (40a), A control method for a refrigeration cycle device comprising a second shut-off valve (26) that shuts off the flow of refrigerant from the other end of the heat source side circuit (20a) toward the utilization side circuit (40a), wherein When the first condition regarding refrigerant leakage to the user-side circuit (40a) side of the refrigerant circuit (10), which is shut off by the first shut-off valve (43) and the second shut-off valve (26), is met, a first recovery operation is performed to recover the refrigerant into the heat source side circuit (20a). This is a control method.

[0028] The 13th aspect is a program that causes the control method of the 12th aspect to be executed. [Brief explanation of the drawing]

[0029] [Figure 1] Figure 1 is a schematic piping diagram of a refrigeration cycle system. [Figure 2] Figure 2 is a block diagram showing the main components of a refrigerant cycle system. [Figure 3] Figure 3 is a flowchart showing a series of operations of the control unit, including the first recovery operation. [Figure 4] Figure 4 is a schematic piping diagram of the refrigeration cycle system according to Modification 1. [Figure 5] Figure 5 is a flowchart showing a series of operations of the control unit, including the first recovery operation according to Modification 1. [Modes for carrying out the invention]

[0030] The embodiments of this disclosure will be described in detail below with reference to the drawings. However, this disclosure is not limited to the embodiments shown below, and various modifications are possible without departing from the technical idea of ​​this disclosure. Since the drawings are for conceptual explanation of this disclosure, dimensions, ratios, or numbers may be exaggerated or simplified as necessary for ease of understanding.

[0031] (1) Overall configuration of the refrigeration cycle system The refrigeration cycle device (1) of this embodiment cools the air in the target space, which is the interior space (S). The interior space (S) of the refrigeration cycle device (1) is formed inside, for example, a refrigerated or frozen display case or a warehouse.

[0032] As shown in Figure 1, the refrigeration cycle device (1) has an outdoor unit (20), a cooling unit (40), and two connecting pipes (5, 6) that connect them. The refrigeration cycle device (1) of this embodiment is a pair type having one outdoor unit (20) and one cooling unit (40). The outdoor unit (20) constitutes a heat source unit installed outdoors. The cooling unit (40) constitutes a utilization unit that air-conditions the target space. More precisely, the cooling unit (40) cools the air in the storage space (S), which is the target space. The two connecting pipes (5, 6) consist of a liquid-side connecting pipe (5) and a gas-side connecting pipe (6). The outdoor unit (20) has a heat source side circuit (20a). The cooling unit (40) has a utilization side circuit (40a). In the refrigeration cycle device (1), the heat source side circuit (20a) and the utilization side circuit (40a) are connected via the liquid side connecting pipe (5) and the gas side connecting pipe (6) to form the refrigerant circuit (10). The refrigerant circuit (10) performs the refrigeration cycle by circulating the refrigerant that is filled. In the following, the terms "upstream" and "downstream" may be used to refer to the direction of refrigerant flow in the refrigerant circuit (10) during normal operation, as described later.

[0033] The refrigerant circuit (10) is filled with R32, a mildly flammable refrigerant. However, the refrigerant filled in the refrigerant circuit (10) is not limited to this; for example, it may be R1234yf or R454C, both mildly flammable refrigerants. Alternatively, the refrigerant filled in the refrigerant circuit (10) may be propane (R290), a highly flammable natural refrigerant, or carbon dioxide (CO2), a natural refrigerant.

[0034] (2) Outdoor unit The outdoor unit (20) includes an outdoor fan (21) and a heat source side circuit (20a). The heat source side circuit (20a) is connected to heat source side equipment including a compressor (22), an outdoor heat exchanger (23), a four-way switching valve (24), a receiver (25), and a heat source side shut-off valve (26).

[0035] The compressor (22) compresses the low-pressure refrigerant and discharges the compressed refrigerant as high-pressure refrigerant. A discharge pipe (31) is connected to the discharge side of the compressor (22), and a suction pipe (32) is connected to the suction side of the compressor (22). The compressor (22) can be composed of scroll type, swing type, turbo type, screw type, etc. The compressor (22) is a variable-speed displacement type.

[0036] The outdoor heat exchanger (23) exchanges heat between the refrigerant and the outdoor air. The outdoor heat exchanger (23) is constructed in a fin-and-tube configuration. The outdoor heat exchanger (23) is an example of a heat source-side heat exchanger. The outdoor fan (21) transports the air passing through the outdoor heat exchanger (23).

[0037] The four-way directional control valve (24) has a first port (P1), a second port (P2), a third port (P3), and a fourth port (P4). The first port (P1) is connected to the discharge pipe (31), and the second port (P2) is connected to the suction pipe (32). The third port (P3) is connected to the gas side end of the outdoor heat exchanger (23), and the fourth port (P4) is connected to the gas side connecting pipe (6). The four-way directional control valve (24) switches between a first state in which the first port (P1) and the third port (P3) are in communication and the second port (P2) and the fourth port (P4) are in communication, and a second state in which the first port (P1) and the fourth port (P4) are in communication and the second port (P2) and the third port (P3) are in communication. The four-way switching valve (24) is in the first state during normal cooling operation and in the second state during defrost operation.

[0038] The heat source circuit (20a) has a liquid pipe (33) between the liquid side end of the outdoor heat exchanger (23) and the liquid side connecting pipe (5). The receiver (25) is installed in the middle of the liquid pipe (33). The receiver (25) stores the liquid refrigerant of the refrigerant circuit (10).

[0039] The heat source side shut-off valve (26) is an example of a second shut-off valve. The heat source side shut-off valve (26) is installed in the heat source side circuit (20a). The heat source side shut-off valve (26) is installed in the middle of the gas pipe (34) of the heat source side circuit (20a). The gas pipe (34) is a refrigerant pipe located from the suction end of the compressor (22) to the gas side connecting pipe (6). The heat source side shut-off valve (26) is installed near the gas side end, which is the connection point between the gas pipe (34) and the gas side connecting pipe (6).

[0040] The heat source side shut-off valve (26) of this embodiment includes a first check valve (51), a second check valve (52), and a solenoid valve (53). The first check valve (51) restricts the flow of refrigerant from the heat source side circuit (20a) to the utilization side circuit (40a). The second check valve (52) and the solenoid valve (53) are provided in a bypass flow path (50) connected to the gas pipe (34) so ​​as to bypass the first check valve (51). Specifically, one end of the bypass flow path (50) is connected to the gas pipe (34) upstream of the first check valve (51), and the other end of the bypass flow path (50) is connected to the gas pipe (34) downstream of the first check valve (51). The second check valve (52) restricts the flow of refrigerant from the utilization side circuit (40a) to the heat source side circuit (20a). The solenoid valve (53) is an on / off valve. The solenoid valve (53) shuts off the heat source side circuit (20a) when it is closed. In this embodiment, since a first check valve (51) is provided in the gas pipe (34), when the solenoid valve (53) is closed, the flow of refrigerant from the heat source side circuit (20a) to the utilization side circuit (40a) is shut off, while the flow in the opposite direction is permitted. The solenoid valve (53) may also be an electromagnetic on / off valve.

[0041] (3) Cooling unit The cooling unit (40) is an example of a user unit. The cooling unit (40) has an internal fan (41) and a user-side circuit (40a). The user-side circuit (40a) has user-side equipment including an internal heat exchanger (42) and an internal expansion valve (43). The cooling unit (40) air-conditions the internal space (S). Here, the cooling unit (40) cools the internal space (S).

[0042] The internal heat exchanger (42) exchanges heat between the refrigerant and the air inside the refrigerator. The internal heat exchanger (42) is constructed in a fin-and-tube configuration. The internal heat exchanger (42) is an example of a heat exchanger on the user side. The internal fan (41) transports the air inside the refrigerator that passes through the internal heat exchanger (42).

[0043] The internal expansion valve (43) reduces the pressure of the refrigerant. The internal expansion valve (43) is an example of a first shut-off valve (43). The internal expansion valve (43) is composed of, for example, an electronic expansion valve. The internal expansion valve (43) may also constitute a user-side shut-off valve that shuts off the user-side circuit (40a) when it is in a closed state.

[0044] The utilization-side circuit (40a) of this embodiment includes a drain pan heater (44). The drain pan heater (44) is positioned in the utilization-side circuit (40a) between the liquid end of the utilization-side circuit (40a) and the internal expansion valve (43). The drain pan heater (44) melts ice and frost that has peeled off the surface of the internal heat exchanger (42) with the refrigerant flowing through it.

[0045] (4) sensor The refrigeration cycle device (1) has a plurality of sensors. The plurality of sensors in this embodiment include a high-pressure sensor (61), a low-pressure sensor (62), and a refrigerant leak sensor (70).

[0046] The high-pressure sensor (61) is installed in the discharge pipe (31). The high-pressure sensor (61) detects the high pressure of the refrigerant circuit (10).

[0047] The low-pressure sensor (62) is an example of a first pressure sensor that detects low pressure in the refrigerant circuit (10). The low-pressure sensor (62) is installed in the gas pipe (34) of the heat source side circuit (20a). The low-pressure sensor (62) is installed in the gas pipe (34) on the user side circuit (40a) side of the heat source side shut-off valve (26).

[0048] The refrigerant leak sensor (70) is positioned around the user-side circuit (40a). The refrigerant leak sensor (70) is positioned, for example, in the internal space (S). Preferably, the refrigerant leak sensor (70) is positioned in an air passage circulating within the internal space (S). The refrigerant leak sensor (70) is a semiconductor type sensor that detects refrigerant. The refrigerant leak sensor (70) outputs a detection signal with increasing intensity (e.g., current value) as the concentration of leaked refrigerant increases. The refrigerant leak sensor (70) is not limited to a semiconductor type, but may also be of other types, such as an infrared type.

[0049] (5) Control Unit As shown in Figures 1 and 2, the refrigeration cycle device (1) has a control unit (100). The control unit (100) controls the refrigerant circuit (10) of the refrigeration cycle device (1). Detection signals from the various sensors described above are input to the control unit (100).

[0050] The control unit (100) includes a heat source controller (110) and a utilization controller (120). The heat source controller (110) is installed in the outdoor unit (20). The utilization controller (120) is installed in the cooling unit (40). The heat source controller (110) and the utilization controller (120) are connected to each other by wire or wireless.

[0051] The heat source controller (110) controls the heat source equipment installed in the outdoor unit (20). Specifically, the heat source controller (110) controls the ON / OFF status of the compressor (22), the rotational speed of the compressor (22), the ON / OFF status of the outdoor fan (21), the rotational speed of the outdoor fan (21), the state of the four-way switching valve (24), and the opening and closing of the heat source side shut-off valve (26). The utilization controller (120) controls the utilization equipment installed in the cooling unit (40). Specifically, the utilization controller (120) controls the ON / OFF status of the internal fan (41), the rotational speed of the internal fan (41), and the opening degree of the internal expansion valve (43).

[0052] As shown in Figure 2, the heat source controller (110) has a first processing unit (111), a first storage unit (112), and a first communication interface (113). The utilization controller (120) has a second processing unit (121), a second storage unit (122), and a second communication interface (123).

[0053] The first processing unit (111) and the second processing unit (121) are implemented by a CPU (Central Processing Unit), a GPU (Graphics Processing Unit), or processing circuitry, which consist of one or more processor cores.

[0054] The first storage unit (112) and the first processing unit (111) are implemented by non-volatile memory and volatile memory. Non-volatile memory includes HDD (Hard Disk Drive), SSD (Solid State Drive), flash memory, ROM (Read Only Memory), etc. Volatile memory includes DRAM (Dynamic Random Access Memory) and SRAM (Solid State Drive), etc.

[0055] The first communication interface (113) and the second communication interface (123) are implemented by communication circuits that perform wired or wireless communication processing.

[0056] (6) Remote controller As shown in Figures 1 and 2, the refrigeration cycle device (1) has a remote controller (130). In this embodiment, the remote controller (130) is connected to the user controller (120) by wire or wireless connection. The remote controller (130) has an operation unit (131) and a display unit (132).

[0057] The control unit (131) consists of buttons, a touch panel, a mouse, etc., which are operated by the user. By operating the control unit (131), the user can switch the operating mode of the refrigeration cycle device (1), change various setting values ​​(judgment values) described later, and switch the screen of the display unit (132).

[0058] The display unit (132) is a display that displays various information on its screen. The display is composed of a liquid crystal panel or an organic EL display. The display may also be a touch panel that doubles as an operation unit. The display unit (132) constitutes a notification unit that notifies the results of a judgment operation. Specifically, the display unit (132) displays first information regarding an abnormality of the shut-off valve on its screen and notifies the operator of the first information. The operator includes users, contractors, maintenance companies, management companies, manufacturers, etc.

[0059] (7) Operating The refrigeration cycle unit (1) switches between normal operation and defrost operation. Figure 1 shows the refrigerant flow in normal operation with solid arrows and the refrigerant flow in defrost operation with dashed arrows.

[0060] In normal operation, the control unit (100) operates the compressor (22), the outdoor fan (21), and the interior fan (41), sets the four-way switching valve (24) to the first state, and adjusts the opening degree of the interior expansion valve (43). In the refrigerant circuit (10), a refrigeration cycle is performed in which the outdoor heat exchanger (23) functions as a heat radiator (condenser) and the interior heat exchanger (42) functions as an evaporator. Specifically, the refrigerant compressed by the compressor (22) dissipates heat in the outdoor heat exchanger (23), is depressurized by the interior expansion valve (43), evaporates in the interior heat exchanger (42), and is drawn back into the compressor (22). In the cooling unit (40), the air in the interior space (S) is cooled by the interior heat exchanger (42).

[0061] In defrost operation, the control unit (100) operates the compressor (22), the outdoor fan (21), and the internal fan (41), sets the four-way switching valve (24) to the second state, opens the solenoid valve (53), and adjusts the opening degree of the internal expansion valve (43). In the refrigerant circuit (10), a refrigeration cycle is performed in which the internal heat exchanger (42) functions as a heat radiator (condenser) and the outdoor heat exchanger (23) functions as an evaporator. Specifically, the refrigerant compressed by the compressor (22) flows through the bypass channel (50), dissipates heat in the internal heat exchanger (42), is depressurized by the internal expansion valve (43), evaporates in the outdoor heat exchanger (23), and is drawn back into the compressor (22). The refrigerant flowing inside the internal heat exchanger (42) melts the frost on the surface of the internal heat exchanger (42).

[0062] (8) Pump-down operation (second recovery operation) During the cooling operation described above (normal operation), if refrigerant leaks from inside the user-side circuit (40a) into the storage space (S), the concentration of refrigerant around the user-side circuit (40a) increases. When the refrigerant leak sensor (70) detects a refrigerant leak, the control unit (100) obtains a signal indicating this. Upon obtaining the signal, the control unit (100) performs a pump-down operation to recover the refrigerant from the user-side circuit (40a) to the heat source-side circuit (20a). The pump-down operation is an example of a second recovery operation.

[0063] Specifically, the second recovery operation is performed by driving the compressor (22) with the internal expansion valve (43) closed when the refrigerant leak sensor (70) detects a refrigerant leak. At this time, the four-way switching valve (24) is in the first state. As a result, the refrigerant downstream (secondary side) of the internal expansion valve (43) in the user-side circuit (40a) is drawn in by the compressor (22) and sent to the heat source-side circuit (20a). Consequently, even if refrigerant leaks in part A on the secondary side of the internal expansion valve (43) in the user-side circuit (40a), leakage of refrigerant from this part A can be suppressed. The refrigerant sent to the heat source-side circuit (20a) is recovered by the receiver (25).

[0064] When the internal expansion valve (43) is closed, it blocks the flow of refrigerant from one end of the heat source circuit (20a) to the utilization circuit (40a). Here, one end of the heat source circuit (20a) is the liquid side end. In other words, when the refrigerant leak sensor (70) detects a refrigerant leak, the closed internal expansion valve (43) blocks the flow of refrigerant from the liquid side end of the heat source circuit (20a) to the utilization circuit (40a). Also, since the first check valve (51) is a check valve, it blocks the flow of refrigerant from the other end of the heat source circuit (20a) to the utilization circuit (40a). The other end of the heat source circuit (20a) is the gas side end. Furthermore, since a second check valve (52) is provided in the bypass passage (50), the flow of refrigerant from the user-side circuit (40a) to the heat source-side circuit (20a) in the bypass passage (50) is restricted during pump-down operation. However, the control unit (100) may close the solenoid valve (53) of the bypass passage (50).

[0065] (9) First recovery operation The first recovery operation will now be described. After the pump-down operation (second recovery operation) is performed, the refrigerant circuit (10) is shut off by the closed internal expansion valve (43) and the first check valve (51). In this state, when the first condition regarding refrigerant leakage from the heat source side circuit (20a) to the utilization side circuit (40a) is met, the control unit (100) performs the first recovery operation to recover refrigerant to the heat source side circuit (20a). Specifically, the first condition is met when refrigerant leakage from the heat source side circuit (20a) to the utilization side circuit (40a) is detected. Thus, the first recovery operation is an operation to recover refrigerant from the utilization side circuit (40a) to the heat source side circuit (20a) when the first condition is met after the completion of the second recovery operation. In the first recovery operation, the control unit (100) drives the compressor (22) with the internal expansion valve (43) closed. In this embodiment, the user-side circuit (40a) refers to the circuit from the low-pressure sensor (62) to the gas pipe (34) and up to the user-side circuit (40a). More precisely, the user-side circuit (40a) refers to the circuit from the low-pressure sensor (62) up to the chamber expansion valve (43) in the user-side circuit (40a). The control flow of the refrigeration cycle device (1) of this embodiment, including the first recovery operation, will be explained below with reference to Figure 3.

[0066] (10) Control flow of refrigeration cycle system In step ST11, the control unit (100) performs normal operation.

[0067] In step ST12, the control unit (100) determines whether the refrigerant leak sensor (70) has detected a refrigerant leak. If a refrigerant leak is detected (YES in step ST12), step ST13 is executed. If no refrigerant leak is detected (NO in step ST12), step ST12 is executed again.

[0068] In step ST13, the control unit (100) performs a pump-down operation. Specifically, the control unit (100) closes the internal expansion valve (43) and the solenoid valve (53). The refrigerant downstream (secondary side) of the internal expansion valve (43) in the user-side circuit (40a) is sucked in by the compressor (22) and sent to the heat source-side circuit (20a). As a result, even if refrigerant leaks in part A on the secondary side of the internal expansion valve (43) in the user-side circuit (40a), leakage of refrigerant from this part A can be suppressed. The refrigerant sent to the heat source-side circuit (20a) is recovered by the receiver (25). With the internal expansion valve (43) and the solenoid valve (53) fully closed and the first check valve (51) in place, leakage of refrigerant from the heat source-side circuit (20a) to the user-side circuit (40a) is suppressed. Therefore, even if refrigerant leaks from the upstream (primary) portion B of the internal expansion valve (43) in the user-side circuit (40a), it is possible to suppress the leakage of refrigerant from the heat source-side circuit (20a) from this portion B.

[0069] In step ST14, the control unit (100) determines whether a predetermined time has elapsed. The predetermined time is, for example, the duration of the pump-down operation that allows sufficient refrigerant to be recovered from the user-side circuit (40a) to the heat source-side circuit (20a). If it is determined that the predetermined time has elapsed, step ST15 is executed. If it is determined that the predetermined time has not elapsed, step ST14 is executed again.

[0070] In step ST15, the control unit (100) determines whether the first condition is met. The first condition is whether the refrigerant pressure (low pressure) detected by the low-pressure sensor (62) has risen to a predetermined pressure ΔP. If the low pressure rises to the predetermined pressure ΔP, it can be determined that refrigerant is leaking from the heat source side circuit (20a) to the utilization side circuit (40a) through at least one of the first check valve (51) and the solenoid valve (53). If it is determined that the first condition is met (YES in step ST15), step ST16 is executed. If it is determined that the first condition is not met (NO in step ST15), step ST15 is executed again. If it is determined that the first condition is not met, the execution of the flow of this control method may be terminated, assuming that there is no refrigerant leakage from the heat source side circuit (20a) to the utilization side circuit (40a). In this case, whether or not to terminate the execution of the flow may be decided by the user, for example.

[0071] In step ST16, the control unit (100) performs the first recovery operation. With the internal expansion valve (43) closed, the control unit (100) drives the compressor (22). As a result, the refrigerant from the utilization side circuit (40a) is recovered again through the gas pipe (34) to the heat source side circuit (20a), and the low pressure decreases.

[0072] In step ST17, the control unit (100) determines whether the second condition, which indicates that the low pressure is below a predetermined value, has been met. Here, the predetermined value is the pressure value shown when the refrigerant in the user-side circuit (40a) has been sufficiently recovered into the heat source-side circuit (20a). If it is determined that the second condition has been met (YES in step ST17), step ST18 is executed. If it is determined that the second condition has not been met (NO in step ST17), step ST17 is executed again.

[0073] In step ST18, the control unit (100) stops the first recovery operation. That is, once the low pressure has dropped sufficiently, it is determined that the refrigerant in the refrigerant circuit (10) has been sufficiently recovered into the heat source side circuit (20a), and therefore the first recovery operation may be stopped.

[0074] (11) Features (11-1) The refrigeration cycle device (1) of this embodiment has a control unit (100) that performs a first recovery operation to recover refrigerant to the heat source side circuit (20a) when a first condition is met in which a leak of refrigerant to the user side circuit (40a) is detected while the refrigerant circuit (10) is shut off by the internal expansion valve (43), the first check valve (51), and the solenoid valve (53).

[0075] According to this embodiment, the first recovery operation allows the refrigerant from the utilization circuit (40a) to be recovered into the heat source circuit (20a), while also suppressing the inflow of refrigerant from the heat source circuit (20a) into the utilization circuit (40a).

[0076] (11-2) In the refrigeration cycle device (1) of this embodiment, the first condition is met when an increase in low pressure is detected. Thus, since an increase in low pressure indicates that refrigerant is leaking into the user-side circuit (40a), this can be designated as the first condition.

[0077] (11-3) In the refrigeration cycle device (1) of this embodiment, the low-pressure sensor (62) is installed on the gas pipe (34) of the heat source side circuit (20a) on the side of the utilization side circuit (40a) rather than the heat source side shut-off valve (26). By detecting an increase in the detected value of the low-pressure sensor (62) in this way, it is possible to determine that the amount of refrigerant leaking from the heat source side circuit (20a) (closed circuit) to the utilization side circuit (40a) exceeds the amount of refrigerant leaking from the utilization side circuit (40a).

[0078] (11-4) The second shut-off valve of this embodiment includes a first check valve (51) and a solenoid valve (53) that restrict the flow of refrigerant from the heat source side circuit (20a) to the utilization side circuit (40a). The first recovery operation can suppress the leakage of refrigerant from the heat source side circuit (20a) to the utilization side circuit (40a) via the first check valve (51) and the solenoid valve (53).

[0079] (11-5) In this embodiment, the second recovery operation of the refrigeration cycle device (1) is an operation in which the compressor (22) is driven with the internal expansion valve (43) closed when the refrigerant leak sensor (70) detects a refrigerant leak. This suppresses refrigerant leakage from the user-side circuit (40a) and allows refrigerant to be recovered from the user-side circuit (40a) to the heat source-side circuit (20a).

[0080] (11-6) In this embodiment, the control unit (100) of the refrigeration cycle device (1) stops the first recovery operation when the second condition is met, which is that the low pressure is below a predetermined value. This allows it to be determined that there is no refrigerant leakage from the heat source side circuit (20a) to the utilization side circuit (40a) when the second condition is met. In other words, the recovery operation can be stopped after the second condition is met.

[0081] (11-7) In this embodiment, the control unit (100) of the refrigeration cycle device (1) performs a second recovery operation to recover refrigerant from the utilization side circuit (40a) to the heat source side circuit (20a), and then performs the first recovery operation when the first condition is met. In this way, in this embodiment, leakage of refrigerant from the heat source side circuit (20a) to the utilization side circuit (40a) can be suppressed after the completion of the second recovery operation (so-called pump-down operation).

[0082] (12) Variations As shown in Figure 4, the second shut-off valve of the modified refrigeration cycle device (1) is an on-off valve (26). The on-off valve (26) is, for example, an electromagnetic on-off valve. The on-off valve (26) is in the open state during normal operation. Specifically, the flow of the control method of modified example 1 will be explained using Figure 5.

[0083] In step ST21, the control unit (100) performs normal operation.

[0084] In step ST22, the control unit (100) determines whether the refrigerant leak sensor (70) has detected a refrigerant leak. If a refrigerant leak is detected (YES in step ST12), step ST13 is executed. If no refrigerant leak is detected (NO in step ST12), step ST12 is executed again.

[0085] In step ST23, the control unit (100) performs a pump-down operation. Specifically, the control unit (100) closes the internal expansion valve (43). The on / off valve (26) remains open. The refrigerant downstream (secondary side) of the internal expansion valve (43) in the user-side circuit (40a) is drawn in by the compressor (22) and sent to the heat source-side circuit (20a). As a result, even if refrigerant leaks in part A on the secondary side of the internal expansion valve (43) in the user-side circuit (40a), leakage of refrigerant from this part A can be suppressed. The refrigerant sent to the heat source-side circuit (20a) is recovered by the receiver (25).

[0086] In step ST24, the control unit (100) determines whether a predetermined time has elapsed. The predetermined time is, for example, the duration of the pump-down operation that allows sufficient refrigerant to be recovered from the user-side circuit (40a) to the heat source-side circuit (20a). If it is determined that the predetermined time has elapsed, step ST25 is executed. If it is determined that the predetermined time has not elapsed, step S24 is executed again.

[0087] In step ST25, the control unit (100) closes the on-off valve (26). This suppresses the inflow of refrigerant from the heat source circuit (20a) to the utilization circuit (40a) via the gas pipe (34).

[0088] In step ST26, the control unit (100) determines whether the first condition is met. The first condition is to determine whether the refrigerant pressure (low pressure) detected by the low-pressure sensor (62) has risen to a predetermined pressure ΔP. If the low pressure rises to the predetermined pressure ΔP, it can be determined that refrigerant is leaking from the heat source side circuit (20a) to the user side circuit (40a) via the on-off valve (26). If it is determined that the first condition is met (YES in step ST26), step ST27 is executed. If it is determined that the first condition is not met (NO in step ST26), step ST26 is executed again. If it is determined that the first condition is not met, the execution of the flow of this control method may be terminated, assuming that there is no refrigerant leakage from the heat source side circuit (20a) to the user side circuit (40a). In this case, whether or not to terminate the execution of the flow may be decided by the user, for example.

[0089] In step ST27, the control unit (100) performs the first recovery operation. With the internal expansion valve (43) closed, the control unit (100) opens the on / off valve (26) and drives the compressor (22). As a result, the refrigerant from the utilization side circuit (40a) is recovered again through the gas pipe (34) to the heat source side circuit (20a), and the low pressure decreases.

[0090] In step ST28, the control unit (100) determines whether the second condition, which indicates that the low pressure is below a predetermined value, has been met. Here, the predetermined value is the pressure value shown when the refrigerant in the user-side circuit (40a) has been sufficiently recovered into the heat source-side circuit (20a). If it is determined that the second condition has been met (YES in step ST28), step ST28 is executed. If it is determined that the second condition has not been met (NO in step ST28), step ST28 is executed again.

[0091] In step ST29, the control unit (100) closes the on-off valve (26) to stop the first recovery operation. That is, once the low pressure has dropped sufficiently, it is determined that the refrigerant in the refrigerant circuit (10) has been sufficiently recovered into the heat source side circuit (20a), and therefore the first recovery operation may be stopped.

[0092] (13) Other embodiments The refrigeration cycle device (1) of the above embodiment and the above modified example may be configured as follows.

[0093] In the above embodiment, the heat source side shut-off valve (26) only needs to have a first check valve (51) and a solenoid valve (53), and does not need to have a second check valve (52). In this case, the solenoid valve (53) is closed except during defrost operation.

[0094] In the above embodiment, it is sufficient to suppress the inflow of refrigerant from the heat source side circuit (20a) to the utilization side circuit (40a) after the pump-down operation is completed, and the solenoid valve (53) may be in a closed state during or after the pump-down operation.

[0095] The low-pressure sensor (62) may be installed in the suction line of the compressor (22). Specifically, the low-pressure sensor (62) may be installed in the gas pipe (low-pressure line) between the suction end of the compressor (22) and the four-way switching valve (24). This suggests that, for example, if the detection of the low-pressure sensor (62) rises after the pump-down operation is completed, it indicates not only that refrigerant is leaking from the user-side circuit (40a) to the heat source-side circuit (20a), but also that refrigerant may be leaking from the line connecting the first port (P1) and the third port (P3) in the first state to the line connecting the second port (P2) and the fourth port (P4) in the four-way switching valve (24). In this case, by performing the first recovery operation, the refrigerant that has leaked into the line connecting the second port (P2) and the fourth port (P4) in the four-way switching valve (24) can be drawn into the compressor (22) and recovered in the receiver (25).

[0096] The second shut-off valve (26) may be the first check valve (51) alone. In this case, a four-way switching valve ( 24) is not provided in the refrigerant circuit (10), and the refrigeration cycle device (1) is configured not to perform defrost operation.

[0097] The first condition may be considered to be met when refrigerant flows from the heat source circuit (20a) to the utilization circuit (40a) after the pump-down operation is completed. The first condition may also be determined based on an index that shows the change in the state of the refrigerant (including pressure changes and temperature changes) when the refrigerant flows from the heat source circuit (20a) to the utilization circuit (40a).

[0098] The control unit (100) may be located in the remote controller (130). The control unit (100) may also be located in a terminal device connected to the refrigeration cycle device (1) via wired or wireless connection. The terminal device may include a server device, a central monitoring device, or a worker's communication terminal. The communication terminal may include a smartphone, tablet, or personal computer.

[0099] (14) Additional remarks The control method of this disclosure includes any of the steps of the embodiments and variations described above.

[0100] The programs of this disclosure are used to cause a computer to perform a control method which includes steps of any of the embodiments and variations described above.

[0101] While embodiments and modifications have been described above, it will be understood that a variety of changes in form and details are possible without departing from the spirit and scope of the claims. Furthermore, these embodiments and modifications may be combined or substituted as appropriate, as long as they do not impair the functions of the subject matter of this disclosure. The terms “First,” “Second,” etc., used above are used to distinguish the phrases to which these terms are attached, and do not limit the number or order of such phrases. [Industrial applicability]

[0102] As described above, this disclosure is useful for refrigeration cycle devices, control methods, and programs. [Explanation of symbols]

[0103] 1. Refrigeration cycle system 10 Refrigerant Circuit 20a Heat source side circuit 22 Compressor 23 Outdoor heat exchanger (heat source side heat exchanger) 26 Heat source side shut-off valve (second shut-off valve) 40 Cooling Unit (Unit Used) 40a User-side circuit 42 Internal heat exchanger (user side heat exchanger) 43. Internal expansion valve (first shut-off valve) 62 Low-pressure sensor (first pressure sensor) 70 Refrigerant leak sensor 100 Control Unit S Interior space (target space)

Claims

1. A refrigerant circuit (10) includes a heat source side circuit (20a) to which a compressor (22) and a heat source side heat exchanger (23) are connected, and a utilization side circuit (40a) to which a utilization side heat exchanger (42) is connected, A utilization unit (40) having the aforementioned utilization-side heat exchanger (42) and air conditioning the target space (S), A refrigerant leak sensor (70) for detecting refrigerant leaks in the user-side circuit (40a), When the refrigerant leak sensor (70) detects a refrigerant leak, a first shut-off valve (43) is activated to block the flow of refrigerant from one end of the heat source side circuit (20a) to the utilization side circuit (40a), A second shut-off valve (26) that blocks the flow of refrigerant from the other end of the heat source side circuit (20a) toward the utilization side circuit (40a), The system includes a control unit (100) that, when the refrigerant circuit (10) is shut off by the first shut-off valve (43) and the second shut-off valve (26), executes a first recovery operation to recover refrigerant to the heat source side circuit (20a) when a first condition regarding refrigerant leakage from the heat source side circuit (20a) to the utilization side circuit (40a) is met. Refrigeration cycle device.

2. The first condition described above is met when a rise in low pressure is detected. The refrigeration cycle apparatus according to claim 1.

3. The refrigerant circuit (10) is further equipped with a first pressure sensor (62) that detects low pressure, The first pressure sensor (62) is located on the user-side circuit (40a) side of the second shut-off valve (26), or in the suction line of the compressor (22). The refrigeration cycle apparatus according to claim 2.

4. The second shut-off valve (26) includes a check valve that restricts the flow of refrigerant from the heat source side circuit (20a) to the utilization side circuit (40a). A refrigeration cycle apparatus according to any one of claims 1 to 3.

5. The control unit (100) In the first recovery operation, when the second condition is met, such that the low pressure is below a predetermined value, the first recovery operation is stopped. The refrigeration cycle apparatus according to claim 2 or claim 3.

6. The control unit (100) After performing a second recovery operation to recover refrigerant from the user-side circuit (40a) to the heat source-side circuit (20a), if the first condition is met, the first recovery operation is performed. A refrigeration cycle apparatus according to any one of claims 1 to 3.

7. The second recovery operation is an operation in which, when the refrigerant leak sensor (70) detects a refrigerant leak, the compressor (22) is driven with the first shut-off valve (43) closed. The refrigeration cycle apparatus according to claim 6.

8. The second shut-off valve (26) is an on / off valve (26), The control unit (100) closes the on / off valve (26) after performing the second recovery operation. The refrigeration cycle apparatus according to claim 6.

9. The control unit (100) executes the first recovery operation by opening the on-off valve (26) when the first condition is met. The refrigeration cycle apparatus according to claim 8.

10. The first shut-off valve (43) is provided in the user-side circuit (40a). A refrigeration cycle apparatus according to any one of claims 1 to 3.

11. The second shut-off valve (26) is provided in the heat source side circuit (20a). A refrigeration cycle apparatus according to any one of claims 1 to 3.

12. A refrigerant circuit (10) includes a heat source side circuit (20a) to which a compressor (22) and a heat source side heat exchanger (23) are connected, and a utilization side circuit (40a) to which a utilization side heat exchanger (42) is connected, A utilization unit (40) having the aforementioned utilization-side heat exchanger (42) and air conditioning the target space (S), A refrigerant leak sensor (70) for detecting refrigerant leaks in the user-side circuit (40a), When the refrigerant leak sensor (70) detects a refrigerant leak, a first shut-off valve (43) is activated to block the flow of refrigerant from one end of the heat source side circuit (20a) to the utilization side circuit (40a), A control method for a refrigeration cycle device comprising a second shut-off valve (26) that shuts off the flow of refrigerant from the other end of the heat source side circuit (20a) toward the utilization side circuit (40a), wherein When the first condition regarding refrigerant leakage to the user-side circuit (40a) of the refrigerant circuit (10), which is shut off by the first shut-off valve (43) and the second shut-off valve (26), is met, a first recovery operation is performed to recover the refrigerant into the heat source side circuit (20a). Control method.

13. A program for causing the control method described in claim 12 to be executed.

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