The present disclosure relates to a refrigeration cycle apparatus, a control method, and a program.

Patent Document 1 discloses a refrigeration cycle apparatus. The refrigeration cycle apparatus includes a shut-off valve that is closed when leakage of a refrigerant from a refrigerant pipe is detected. Closing the shut-off valve can reduce the leakage of refrigerant from the refrigerant pipe. If a shut-off valve does not operate normally, the reliability of the refrigeration cycle apparatus may be impaired. To address this problem, the refrigeration cycle apparatus of Patent Document 1 performs a determination action for determining whether the shut-off valve is operating normally, based on the pressure of the refrigerant observed when the shut-off valve is closed during the operation of a compressor.

Patent Document 1: Japanese Patent No. 6944987

During the period of the determination action described in Patent Document 1, the refrigeration cycle apparatus cannot perform normal operation. Accordingly, air conditioning of a target space is impaired.

An object of the present disclosure is to reduce impairment of air conditioning of a target space due to a determination action for a shut-off valve.

A first aspect is directed to a refrigeration cycle apparatus. The refrigeration cycle apparatus includes: a refrigerant circuit (10) including: a heat-source-side circuit (20a) having a compressor (22) and a heat-source-side heat exchanger (23); and a utilization-side circuit (45) having a utilization-side heat exchanger (42); a utilization unit (40) having the utilization-side heat exchanger (42) and configured to condition air in a target space (S); a refrigerant leakage sensor (70) configured to detect leakage of a refrigerant in the utilization-side circuit (45); a shut-off valve (26, 43, 43A, 43B, 46A, 46B) configured to shut off a flow of the refrigerant from the heat-source-side circuit (20a) to the utilization-side circuit (45) when the refrigerant leakage sensor (70) detects leakage of the refrigerant; a controller (100) configured to execute a determination action including: a first control to close the shut-off valve (26, 43, 43A, 43B, 46A, 46B) or reduce an opening degree of the shut-off valve (26, 43, 43A, 43B, 46A, 46B) during operation of the compressor (22); and a second control to determine, after the first control, whether the shut-off valve (26, 43) is abnormal, based on a pressure or temperature of the refrigerant in the refrigerant circuit (10); and a notification unit (132) configured to provide a notification of a result of the determination action. The controller (100) is configured to execute the determination action in response to acquisition of a first signal for setting the utilization unit (40) to a thermo-off state.

According to the first aspect, the controller (100) performs the determination action in response to acquisition of a first signal for setting the utilization unit (40) to a thermo-off state. When the first signal (thermo-off signal) is acquired, the temperature of the target space (S) is close to a target temperature. Thus, continuous air-conditioning operation of the target space (S) by the utilization unit (40) is not required. According to the first aspect, since the determination action is performed at this timing, impairment of air conditioning in the target space (S) due to the determination action can be suppressed.

A second aspect is an embodiment of the first aspect. In the second aspect, in the determination action, the controller (100) executes a third control to stop the compressor (22) before the second control.

According to the second aspect, the controller (100) determines whether the shut-off valve (26, 43) is abnormal based on the pressure or temperature of the refrigerant in the refrigerant circuit (10) after the compressor (22) is stopped by the third control. Stopping the compressor (22) reduces the likelihood of changes in the pressure or temperature of the refrigerant, which can improve the accuracy of the determination as to whether the shut-off valve (26, 43) is abnormal.

A third aspect is an embodiment of the second aspect. In the third aspect, the controller (100) determines whether the shut-off valve (26, 43) is abnormal based on a change in a high pressure of the refrigerant circuit (10) or on a change in a low pressure of the refrigerant circuit (10).

According to the third aspect, the controller determines whether the shut-off valve (26, 43) is abnormal based on a change in high pressure or on a change in low pressure, because if the shut-off valve (26, 43) does not operate normally and is not fully closed, the rate of change in the high pressure or the low pressure increases.

A fourth aspect is an embodiment of the second or third aspect. In the fourth aspect, the controller (100) prohibits restart of operation of the compressor (22) for a predetermined first period after the third control. The controller (100) executes the second control during the first period.

According to the fourth aspect, the compressor (22) can be protected by prohibiting the restart of operation of the compressor (22) for the first period. The controller (100) determines whether the shut-off valve (26, 43, 43A, 43B, 46A, 46B) is abnormal, during the first period. Thus, the period for protecting the compressor (22) can be used to determine whether the shut-off valve (26, 43, 43A, 43B, 46A, 46B) is abnormal.

A fifth aspect is an embodiment of any one of the first to fourth aspects. In the fifth aspect, the utilization-side circuit (45) includes: a first utilization-side circuit (45A) having a first utilization-side heat exchanger (42A); and a second utilization-side circuit (45B) having a second utilization-side heat exchanger (42B), the first utilization-side circuit (45A) and the second utilization-side circuit (45B) being connected to each other in parallel. The utilization unit (40) includes: a first utilization unit (40A) having the first utilization-side heat exchanger (42A); and a second utilization unit (40B) having the second utilization-side heat exchanger (42B). The refrigerant leakage sensor (70) includes: a first refrigerant leakage sensor (70A) configured to detect leakage of the refrigerant from the first utilization-side circuit (45A); and a second refrigerant leakage sensor (70B) configured to detect leakage of the refrigerant from the second utilization-side circuit (45B). The shut-off valve includes: a first utilization-side shut-off valve (43A, 46A) configured to shut off a flow of the refrigerant from the heat-source-side circuit (20a) to the first utilization-side circuit (45A) when the first refrigerant leakage sensor (70A) detects leakage of the refrigerant; and a second utilization-side shut-off valve (43B, 46B) configured to shut off a flow of the refrigerant from the heat-source-side circuit (20a) to the second utilization-side circuit (45B) when the second refrigerant leakage sensor (70B) detects leakage of the refrigerant.

According to the fifth aspect, abnormality of the first utilization-side shut-off valve (43A, 46A) and the second utilization-side shut-off valve (43B, 46B) can be determined in the multi-type refrigeration cycle apparatus including the first utilization unit (40A) and the second utilization unit (40B).

A sixth aspect is an embodiment of the fifth aspect. In the sixth aspect, the first signal includes: a first thermo-off signal for setting the first utilization unit (40A) to a thermo-off state; and a second thermo-off signal for setting the second utilization unit (40B) to a thermo-off state. The controller (100) is configured to execute, when only the first thermo-off signal is acquired, a first determination action as the determination action including: the first control to close the first utilization-side shut-off valve (43A, 46A) or reduce an opening degree of the first utilization-side shut-off valve (43A, 46A); and a second control to determine, after the first control, whether the first utilization-side shut-off valve (43A, 46A) is abnormal, based on a pressure or temperature of the refrigerant in the refrigerant circuit (10). The controller (100) is configured to execute, when only the second thermo-off signal is acquired, a second determination action as the determination action including: the first control to close the second utilization-side shut-off valve (43B, 46B) or reduce an opening degree of the second utilization-side shut-off valve (43B, 46B); and a second control to determine, after the first control, whether the second utilization-side shut-off valve (43B, 46B) is abnormal, based on a pressure or temperature of the refrigerant in the refrigerant circuit (10).

According to the sixth aspect, the controller (100) closes the first utilization-side shut-off valve (43A, 46A) or reduces the opening degree of the first utilization-side shut-off valve (43A, 46A) in response to acquisition of the first thermo-off signal, and determines whether the first utilization-side shut-off valve (43A, 46A) is abnormal. The controller (100) closes the second utilization-side shut-off valve (43B, 46B) or reduces the opening degree of the second utilization-side shut-off valve (43B, 46B) in response to acquisition of the second thermo-off signal, and determines whether the second utilization-side shut-off valve (43B, 46B) is abnormal.

A seventh aspect is an embodiment of the sixth aspect. In the seventh aspect, the controller (100) is configured to continue an air-conditioning action of the second utilization unit (40B) during the first determination action. The controller (100) is configured to continue an air-conditioning action of the first utilization unit (40A) during the second determination action.

According to the seventh aspect, air conditioning of the target space can be maintained by the second utilization unit (40B) while an abnormality determination is being performed on the first utilization-side shut-off valve (43A, 46A). Air conditioning of the target space can be maintained by the first utilization unit (40A) while an abnormality determination is being performed on the second utilization-side shut-off valve (43B, 46B).

An eighth aspect is an embodiment of the fifth aspect. In the eighth aspect, the first signal includes: a first thermo-off signal for setting the first utilization unit (40A) to a thermo-off state; and a second thermo-off signal for setting the second utilization unit (40B) to a thermo-off state. The controller (100) is configured to execute the determination action in response to acquisition of the first thermo-off signal and the second thermo-off signal. The controller (100) is configured to execute, when the first thermo-off signal and the second thermo-off signal are acquired, a third determination action as the determination action including: a first control to close the first utilization-side shut-off valve (43A, 46A) or reduce an opening degree of the first utilization-side shut-off valve (43A, 46A) and to close the second utilization-side shut-off valve (43B, 46B) or reduce an opening degree of the second utilization-side shut-off valve (43B, 46B); and a second control to determine, after the first control, whether the first utilization-side shut-off valve (43A, 46A) and the second utilization-side shut-off valve (43B, 46B) are abnormal, based on a pressure or temperature of the refrigerant in the refrigerant circuit (10). The controller (100) is configured to execute a third control to stop the compressor (22) before the second control in the third determination action.

According to the eighth aspect, in response to acquisition of the first thermo-off signal and the second thermo-off signal, the controller (100) closes the first utilization-side shut-off valve (43A, 46A) or reduces the opening degree of the first utilization-side shut-off valve (43A, 46A), and closes the second utilization-side shut-off valve (43B, 46B) or reduces the opening degree of the second utilization-side shut-off valve (43B, 46B), and determines whether the first utilization-side shut-off valve (43A, 46A) and the second utilization-side shut-off valve (43B, 46B) are abnormal.

A ninth aspect is an embodiment of any one of the first to eighth aspects. In the ninth aspect, the shut-off valve includes: a utilization-side liquid shut-off valve (43A, 43B) provided on a liquid side of the utilization-side heat exchanger (42) in the utilization-side circuit (45); and a heat-source-side shut-off valve (26) provided in the heat-source-side circuit (20a). In the second control, the controller (100) determines whether the utilization-side liquid shut-off valve (43A, 43B) is abnormal based on a low pressure of the refrigerant circuit (10), and determines whether the heat-source-side shut-off valve (26) is abnormal based on a high pressure of the refrigerant circuit (10).

According to the ninth aspect, in the second control, the controller (100) determines whether the utilization-side liquid shut-off valve (43A, 43B) is abnormal based on the low pressure of the refrigerant circuit (10), because if the utilization-side liquid shut-off valve (43A, 43B) is abnormal, it affects the low pressure of the refrigerant circuit (10). In the second control, the controller (100) determines whether the heat-source-side shut-off valve (26) is abnormal based on the high pressure of the refrigerant circuit (10), because if the heat-source-side shut-off valve (26) is abnormal, it affects the high pressure of the refrigerant circuit (10).

A tenth aspect is an embodiment of any one of the first to eighth aspects. In the tenth aspect, the shut-off valve includes: a utilization-side liquid shut-off valve (43A, 43B) provided on a liquid side of the utilization-side heat exchanger (42) in the utilization-side circuit (45); and a utilization-side gas shut-off valve (46A, 46B) provided on a gas side of the utilization-side heat exchanger (42) in the utilization-side circuit (45). In the second control, the controller (100) determines whether the utilization-side liquid shut-off valve (43A, 43B) is abnormal based on a differential pressure between an upstream side and a downstream side of the utilization-side liquid shut-off valve (43A, 43B). The controller (100) determines whether the utilization-side gas shut-off valve (46A, 46B) is abnormal based on a differential pressure between an upstream side and a downstream side of the utilization-side gas shut-off valve (46A, 46B).

According to the tenth aspect, in the second control, the controller (100) determines whether the utilization-side liquid shut-off valve (43A, 43B) is abnormal based on the differential pressure between the upstream side and the downstream side of the utilization-side liquid shut-off valve (43A, 43B), because if the utilization-side liquid shut-off valve (43A, 43B) is abnormal, it affects the differential pressure between the upstream side and the downstream side of the utilization-side liquid shut-off valve (43A, 43B).

An eleventh aspect is an embodiment of any one of the first to tenth aspects. In the eleventh aspect, the controller (100) includes a storage (133) configured to store a determination result of the determination action as a determination history. The refrigeration cycle apparatus further includes a display (132) configured to display the determination history stored in the storage (133).

According to the eleventh aspect, the storage (133) stores the determination result of the determination action as the determination history. The display (132) displays the determination history. Thus, by checking the display (132), the user or the like can recognize past abnormalities of the shut-off valve (26, 43).

A twelfth aspect is an embodiment of the eleventh aspect. In the twelfth aspect, the controller (100) performs the determination action each time the number of acquisitions of the first signal reaches a predetermined number equal to or greater than two.

According to the twelfth aspect, the controller (100) does not perform the determination action each time the first signal, which is the thermo-off signal, is acquired, but performs the determination action each time the number of acquisitions of the first signal reaches the predetermined number equal to or greater than two. This can reduce the frequency of the determination action and the amount of data of the determination history stored in the storage (133).

A thirteenth aspect is an embodiment of any one of the first to twelfth aspects. In the thirteenth aspect, the heat-source-side circuit (20a) has a receiver (25) configured to store the refrigerant. In the first control, the controller (100) controls the refrigerant circuit (10) such that the refrigerant in the utilization-side circuit (45) is sent to the receiver (25).

According to the thirteenth aspect, in the first control, sending the refrigerant in the utilization-side circuit (45) to the receiver (25) can reduce the accumulation of liquid refrigerant in the utilization-side circuit (45).

A fourteenth aspect is an embodiment of any one of the first to thirteenth aspects. In the fourteenth aspect, the utilization unit comprises a cooling unit (40) configured to cool an internal space (S) that is the target space.

According to the fourteenth aspect, impairment of cooling in the internal space (S) due to the determination action can be suppressed. It is thus possible to ensure the quality of stored items in the internal space (S).

A fifteenth aspect is directed to a method for controlling a refrigeration cycle apparatus. The refrigeration cycle apparatus includes: a refrigerant circuit (10) including: a heat-source-side circuit (20a) having a compressor (22) and a heat-source-side heat exchanger (23); and a utilization-side circuit (45) having a utilization-side heat exchanger (42); a utilization unit (40) having the utilization-side heat exchanger (42) and configured to condition air in a target space (S); a refrigerant leakage sensor (70) configured to detect leakage of a refrigerant in the utilization-side circuit (45); and a shut-off valve (26, 43) configured to shut off a flow of the refrigerant from the heat-source-side circuit (20a) to the utilization-side circuit (45) when the refrigerant leakage sensor (70) detects leakage of the refrigerant. The method includes a determination action that is executed in response to acquisition of a first signal for setting the utilization unit (40) to a thermo-off state. The determination action includes: a first control to close the shut-off valve (26, 43) or reduce an opening degree of the shut-off valve (26, 43) during operation of the compressor (22); and a second control to determine, after the first control, whether the shut-off valve (26, 43) is abnormal, based on a pressure or temperature of the refrigerant in the refrigerant circuit (10).

A sixteenth aspect is a program to cause a computer to execute the method of the fifteenth aspect.

• [FIG. 1] FIG. 1 is a schematic piping system diagram of a refrigeration cycle apparatus.
• [FIG. 2] FIG. 2 is a block diagram illustrating main devices of the refrigeration cycle apparatus.
• [FIG. 3] FIG. 3 is a schematic piping system diagram of the refrigeration cycle apparatus, and illustrates the flow of a refrigerant when shut-off valves are working or during a pump-down action.
• [FIG. 4] FIG. 4 is a basic flowchart including a determination action.
• [FIG. 5] FIG. 5 is a flowchart of the determination action.
• [FIG. 6] FIG. 6 illustrates an example of a screen of a display.
• [FIG. 7] FIG. 7 is a schematic configuration diagram of a refrigeration cycle system according to a first variation.
• [FIG. 8] FIG. 8 is a piping system diagram of a refrigeration cycle apparatus according to a second variation.
• [FIG. 9] FIG. 9 is a flowchart for explaining determinations as to execution of thermo-off control and a determination action according to the second variation.
• [FIG. 10] FIG. 10 is a piping system diagram of a refrigeration cycle apparatus according to a third variation.
• [FIG. 11] FIG. 11 is a flowchart for explaining determinations as to execution of thermo-off control and a determination action according to the third variation.
• [FIG. 12] FIG. 12 is a flowchart of a first determination action according to the third variation.
• [FIG. 13] FIG. 13 is a flowchart of a second determination action according to the third variation.
• [FIG. 14] FIG. 14 is a flowchart of first control in a third determination action according to the third variation.
• [FIG. 15] FIG. 15 is a flowchart of second control in the third determination action according to the third variation.

Embodiments of the present disclosure will be described in detail below with reference to the drawings. The present disclosure is not limited to the embodiment shown below, and various changes can be made within the scope without departing from the technical concept of the present disclosure. Since each of the drawings is intended to illustrate the present disclosure conceptually, dimensions, ratios, or numbers may be exaggerated or simplified as necessary for ease of understanding.

A refrigeration cycle apparatus (1) of this embodiment cools air in an internal space (S) that is a target space. The internal space (S) is formed in the inside of a showcase for cold storage or refrigeration, or a warehouse.

As illustrated in FIG. 1, the refrigeration cycle apparatus (1) includes an outdoor unit (20), a cooling unit (40), and two connection pipes (5, 6) coupling these units. The refrigeration cycle apparatus (1) of this embodiment is a pair-type refrigeration cycle apparatus including the single outdoor unit (20) and the single cooling unit (40). The outdoor unit (20) constitutes a heat source unit placed outdoors. The cooling unit (40) constitutes a utilization unit that conditions the air in the target space. Strictly speaking, the cooling unit (40) cools the air in the internal space (S) that is the target space.

The two connection pipes (5, 6) include a liquid-side connection pipe (5) and a gas-side connection pipe (6). The outdoor unit (20) includes a heat-source-side circuit (20a). The cooling unit (40) includes a utilization-side circuit (45). In the refrigeration cycle apparatus (1), the heat-source-side circuit (20a) and the utilization-side circuit (45) are connected through the liquid-side connection pipe (5) and the gas-side connection pipe (6) to form a refrigerant circuit (10). The refrigerant circuit (10) is filled with a refrigerant which circulates to perform a refrigeration cycle.

The refrigeration cycle apparatus (1) includes a refrigerant leakage sensor (70), and an internal expansion valve (43) and a heat-source-side shut-off valve (26) that serve as shut-off valves. The refrigerant leakage sensor (70) detects leakage of the refrigerant from the utilization-side circuit (45). When the refrigerant leakage sensor (70) detects leakage of the refrigerant, the internal expansion valve (43) and the heat-source-side shut-off valve (26) are closed. The internal expansion valve (43) is hereinafter also referred to as the "utilization-side shut-off valve."

The outdoor unit (20) includes an outdoor fan (21) and the heat-source-side circuit (20a). The heat-source-side circuit (20a) includes heat-source-side devices including a compressor (22), an outdoor heat exchanger (23), a four-way switching valve (24), and a receiver (25).

The compressor (22) compresses a low-pressure refrigerant, and discharges the compressed refrigerant as a 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) is of a scroll type, a swing type, a turbo type, a screw type, or the like. The compressor (22) is a variable displacement compressor with a variable number of rotations.

The outdoor heat exchanger (23) exchanges heat between the refrigerant and outdoor air. The outdoor heat exchanger (23) is a fin-and-tube heat exchanger. The outdoor heat exchanger (23) is an example of a heat-source-side heat exchanger. The outdoor fan (21) transfers air passing through the outdoor heat exchanger (23).

The four-way switching 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 connection pipe (6). The four-way switching valve (24) is switchable between a first state in which the first port (P1) and the third port (P3) communicate with each other, and the second port (P2) and the fourth port (P4) communicate with each other, and a second state in which the first port (P1) and the fourth port (P4) communicate with each other, and the second port (P2) and the third port (P3) communicate with each other. The four-way switching valve (24) is in the first state during normal cooling operation, and is in the second state during defrosting operation.

The heat-source-side circuit (20a) includes a liquid pipe (33) between the liquid-side end of the outdoor heat exchanger (23) and the liquid-side connection pipe (5). The receiver (25) is provided in the liquid pipe (33). The receiver (25) stores a liquid refrigerant in the refrigerant circuit (10).

The heat-source-side circuit (20a) includes the heat-source-side shut-off valve (26). The heat-source-side shut-off valve (26) is provided between the liquid-side end of the heat-source-side circuit (20a) and the receiver (25) in the heat-source-side circuit (20a). The heat-source-side shut-off valve (26) is configured as an electromagnetic on-off valve. The heat-source-side shut-off valve (26) may be an electric valve. The heat-source-side circuit (20a) may be provided with both an electromagnetic on-off valve and an electric valve as heat-source-side shut-off valves. The heat-source-side shut-off valve (26) shuts off the heat-source-side circuit (20a) when closed. The heat-source-side shut-off valve (26) shuts off the flow of the refrigerant from the heat-source-side circuit (20a) to the utilization-side circuit (45).

The cooling unit (40) is an example of a utilization unit. The cooling unit (40) includes an internal fan (41) and the utilization-side circuit (45). The utilization-side circuit (45) includes utilization-side devices including an internal heat exchanger (42) and the internal expansion valve (43).

The internal heat exchanger (42) exchanges heat between the refrigerant and internal air. The internal heat exchanger (42) is a fin-and-tube heat exchanger. The internal heat exchanger (42) is an example of a utilization-side heat exchanger. The internal fan (41) transfers the internal air passing through the internal heat exchanger (42).

The internal expansion valve (43) decompresses the refrigerant. The internal expansion valve (43) is configured as an electronic expansion valve, for example. The internal expansion valve (43) shuts off the utilization-side circuit (45) when closed. The internal expansion valve (43) constitutes a utilization-side shut-off valve that shuts off the flow of the refrigerant from the heat-source-side circuit (20a) to the utilization-side circuit (45). The utilization-side circuit (45) may be provided with an internal expansion valve and a utilization-side shut-off valve as separate members.

The utilization-side circuit (45) of this embodiment includes a drain pan heater (44). The drain pan heater (44) is disposed between the liquid-side end of the utilization-side circuit (45) and the internal expansion valve (43) in the utilization-side circuit (45). The drain pan heater (44) melts ice and frost that have fallen off the surface of the internal heat exchanger (42) using the refrigerant flowing therethrough.

The refrigeration cycle apparatus (1) includes a plurality of sensors. The plurality of sensors of this embodiment include a high-pressure sensor (61), a low-pressure sensor (62), a liquid-pressure sensor (63), an internal temperature sensor (64), and the refrigerant leakage sensor (70).

The high-pressure sensor (61) is provided in the discharge pipe (31). The high-pressure sensor (61) detects the high pressure of the refrigerant circuit (10). The low-pressure sensor (62) is provided in the suction pipe (32). The low-pressure sensor (62) detects the low pressure of the refrigerant circuit (10). The liquid-pressure sensor (63) is provided between the liquid-side end of the heat-source-side circuit (20a) and the heat-source-side shut-off valve (26) in the heat-source-side circuit (20a). The liquid-pressure sensor (63) detects the liquid pressure of a liquid line between the heat-source-side shut-off valve (26) and the utilization-side shut-off valve (43).

The internal temperature sensor (64) is disposed in the internal space (S). The internal temperature sensor (64) detects the temperature of the internal air in the internal space (S).

The refrigerant leakage sensor (70) is disposed on the periphery of the utilization-side circuit (45). The refrigerant leakage sensor (70) is disposed, for example, in the internal space (S). The refrigerant leakage sensor (70) is preferably disposed in an air flow path that circulates in the internal space (S). The refrigerant leakage sensor (70) is a semiconductor-type sensor that detects the refrigerant. The refrigerant leakage sensor (70) outputs a detection signal having a higher intensity (e.g., current value) as the concentration of the leaked refrigerant increases. The refrigerant leakage sensor (70) is not limited to the semiconductor type, and may be of other types such as an infrared type.

As shown in FIG. 1 and FIG. 2, the refrigeration cycle apparatus (1) includes a controller (100). The controller (100) controls the refrigerant circuit (10) of the refrigeration cycle apparatus (1). The controller (100) receives detection signals from various sensors described above.

The controller (100) includes a heat source controller (110), a utilization controller (120), and a remote controller (130). The heat source controller (110) is provided in the outdoor unit (20). The utilization controller (120) is provided in the cooling unit (40). The heat source controller (110) and the utilization controller (120) are connected to each other via wired or wireless communication. The remote controller (130) is connected to the utilization controller (120) via wired or wireless communication.

The heat source controller (110) controls the heat-source-side devices provided in the outdoor unit (20). Specifically, the heat source controller (110) controls the on/off state of the compressor (22), the number of rotations of the compressor (22), the on/off state of the outdoor fan (21), the number of rotations of the outdoor fan (21), the state of the four-way switching valve (24), and the opening/closing of the heat-source-side shut-off valve (26). The utilization controller (120) controls the utilization-side devices provided in the cooling unit (40). Specifically, the utilization controller (120) controls the on/off state of the internal fan (41), the number of rotations of the internal fan (41), and the opening degree of the internal expansion valve (43).

As shown in FIG. 2, the heat source controller (110) includes a first processor (111), a first storage (112), and a first communication interface (113). The utilization controller (120) includes a second processor (121), a second storage (122), and a second communication interface (123).

The first processor (111) and the second processor (121) are implemented by a central processing unit (CPU), a graphics processing unit (GPU), or processing circuitry including one or more processor cores.

The first communication interface (113) and the second communication interface (123) are implemented by a communication circuit that executes a wired or wireless communication process.

The remote controller (130) includes an operation unit (131), a display (132), and a third storage (133). The operation unit (131) includes a button, a touch panel, and a mouse operated by a user or the like. By operating the operation unit (131), the user can switch the operating mode of the refrigeration cycle apparatus (1), change various set values (determination values) to be described later, and switch the screen of the display (132).

The display (132) is a display unit that displays various types of information on the screen. The display unit is configured as a liquid crystal panel or an organic EL panel. The display unit may be a touch panel that is also used as the operation unit. The display (132) constitutes a notification unit that provides notification of the result of a determination action. Specifically, the display (132) displays first information on an abnormality of a shut-off valve on the screen to notify an operator of the first information. Examples of the operator include users and staff members of a contractor, a maintenance company, a management company, and a manufacturer.

The first storage (112), the second storage (122), and the third storage (133) are implemented by nonvolatile memory and volatile memory. Examples of the nonvolatile memory include a hard disk drive (HDD), a solid state drive (SSD), flash memory, and readonly memory (ROM). Examples of the volatile memory include dynamic random access memory (DRAM) and static random access memory (SRAM).

The controller (100) performs a determination action for determining whether shut-off valves, specifically, the heat-source-side shut-off valve (26) and the utilization-side shut-off valve (43), are abnormal. In this embodiment, the third storage (133) stores the determination result of the determination action as a determination history. The first storage (112) or the second storage (122) may store the determination result of the determination action as a determination history. The first storage (112) also stores values detected by the various sensors described above as appropriate.

The refrigeration cycle apparatus (1) switches between the cooling operation and the defrosting operation. In FIG. 1, the flow of the refrigerant in the cooling operation is indicated by solid arrows, and the flow of the refrigerant in the defrosting operation is indicated by dashed arrows.

In the cooling operation, the controller (100) operates the compressor (22), the outdoor fan (21), and the internal fan (41), brings the four-way switching valve (24) into the first state, opens the heat-source-side shut-off valve (26), and adjusts the opening degree of the internal expansion valve (43). The refrigerant circuit (10) performs a refrigeration cycle in which the outdoor heat exchanger (23) functions as a radiator (condenser) and the internal heat exchanger (42) functions as an evaporator. Specifically, the refrigerant compressed by the compressor (22) dissipates heat in the outdoor heat exchanger (23), is decompressed by the internal expansion valve (43), evaporates in the internal heat exchanger (42), and is sucked into the compressor (22). In the cooling unit (40), the internal heat exchanger (42) cools the air in the internal space (S).

In the defrosting operation, the controller (100) operates the compressor (22), the outdoor fan (21), and the internal fan (41), brings the four-way switching valve (24) into the second state, opens the heat-source-side shut-off valve (26), and adjusts the opening degree of the internal expansion valve (43). The refrigerant circuit (10) performs a refrigeration cycle in which the internal heat exchanger (42) functions as a radiator (condenser) and the outdoor heat exchanger (23) functions as an evaporator. Specifically, the refrigerant compressed by the compressor (22) dissipates heat in the internal heat exchanger (42), is decompressed by the internal expansion valve (43), evaporates in the outdoor heat exchanger (23), and is sucked into the compressor (22). The refrigerant flowing through the interior of the internal heat exchanger (42) melts frost on the surface of the internal heat exchanger (42).

In the cooling operation (normal operation) described above, leakage of the refrigerant from the inside to the outside of the utilization-side circuit (45) increases the concentration of the refrigerant around the utilization-side circuit (45). When the refrigerant leakage sensor (70) detects leakage of the refrigerant, the controller (100) acquires a signal indicating the leakage. The controller (100) that has acquired the signal closes the utilization-side shut-off valve (43) and the heat-source-side shut-off valve (26). At this time, the compressor (22) is in the operating state, and the four-way switching valve (24) is in the first state. Thus, as illustrated in FIG. 3, the refrigerant on the downstream (secondary) side of the utilization-side shut-off valve (43) in the utilization-side circuit (45) is sucked by the compressor (22), and is sent to the heat-source-side circuit (20a). As a result, even if the refrigerant leaks from a portion A on the secondary side of the utilization-side shut-off valve (43) in the utilization-side circuit (45), the leakage of the refrigerant from the portion A can be reduced. The refrigerant sent to the heat-source-side circuit (20a) is collected by the receiver (25).

The heat-source-side shut-off valve (26) in the closed state prevents the refrigerant in the heat-source-side circuit (20a) from being sent to the liquid-side connection pipe (5). Thus, even if the refrigerant leaks, for example, from a portion B on the upstream (primary) side of the utilization-side shut-off valve (43) in the utilization-side circuit (45), the leakage of the refrigerant in the heat-source-side circuit (20a) from this portion B can be reduced.

The utilization-side shut-off valve (43) and the heat-source-side shut-off valve (26) may not operate normally. The reasons for this include mechanical failure of the shut-off valve (26, 43), control failure of the shut-off valve, clogging of the inside of the shut-off valve with impurities in the refrigerant. If the utilization-side shut-off valve (43) or the heat-source-side shut-off valve (26) does not operate normally when the refrigerant leaks, the shut-off valve (26, 43) cannot sufficiently shut off the refrigerant circuit (10), and the refrigerant passes through the shut-off valve (26, 43). As a result, the reliability of the refrigeration cycle apparatus (1) is impaired. The controller (100) performs a determination action for determining whether such an abnormality has occurred in the shut-off valve (26, 43).

A basic flow before the execution of the determination action will be described with reference to FIG. 4. When the normal operation in step ST11 is executed, the controller (100) controls the number of rotations of the compressor (22) such that an internal temperature (Tr) approaches a target temperature (Ts). The internal temperature (Tr) is a value detected by the internal temperature sensor (64). The target temperature (Ts) corresponds to a set temperature set by the user operating the remote controller (130).

If, in step ST12, the difference (ΔT) between the internal temperature (Tr) and the target temperature (Ts) is less than a predetermined first value (T1), the controller (100) acquires a first signal for setting the cooling unit (40) to a thermo-off state in step ST13. The "thermo-off state" as used herein refers to a state in which the air conditioning function of the utilization unit for the target space (S) is substantially stopped as the temperature of the target space (S) approaches the target temperature. In this embodiment, the "thermo-off state" refers to a state in which the cooling function of the cooling unit (40) for the internal space (S) is substantially stopped as the internal temperature (Tr) approaches the target temperature (Ts). The phrase "acquire(s) a first signal" as used herein includes not only the reception of the first signal from the outside of the controller (100) by the controller (100) but also the generation of the first signal by the internal processing of the controller (100).

Next, in step ST14, the controller (100) determines whether or not the number of acquisitions (N) of the first signal acquired so far has reached a predetermined number (Ns). When the number of acquisitions (N) reaches the predetermined number (Ns), the determination action in step ST40 is executed. The number of acquisitions (N) is the cumulative value of the number of times that the first signal has been acquired since the previous determination action was performed. The predetermined number (Ns) is a predetermined value equal to or greater than two, and is set by the user operating the remote controller (130). The predetermined number (Ns) is set such that the determination action is executed, for example, about once a month.

If, in step ST14, the number of acquisitions (N) has not reached the predetermined number (Ns), the controller (100) executes a normal thermo-off action in step ST15. In the thermo-off action of this embodiment, the controller (100) fully closes the internal expansion valve (43), closes the heat-source-side shut-off valve (26), and stops the compressor (22) after executing a pump-down action. After the compressor (22) has stopped, the controller (100) starts counting of a protection timer of the compressor (22). In the thermo-off action, the controller (100) may operate the internal fan (41), may reduce the number of rotations of the internal fan (41), or may stop the internal fan (41). The thermo-off action of this embodiment is the same as steps ST41 to ST47 of the determination action. Thus, the detailed description thereof will be omitted.

When the thermo-off action is executed, the internal temperature (Tr) rises. Thereafter, if the difference (ΔT) between the internal temperature (Tr) and the target temperature (Ts) is greater than a predetermined second value (T2) in step ST16, and a value of the protection timer of the compressor is greater than a predetermined value (e.g., five minutes) in step ST17, the controller (100) executes a thermo-on action, i.e., the normal operation described above, in step ST18. The second value (T2) is preferably greater than the first value (T1), but may be the same as the first value (T1). In step ST18, the controller (100) operates the compressor (22), opens the heat-source-side shut-off valve (26), and adjusts the opening degree of the internal expansion valve (43). As a result, the internal heat exchanger (42) functions as an evaporator, and the air in the internal space (S) is cooled again.

The determination action in step ST40 will be described in detail with reference to FIG. 5. When the determination action is started, the first control in steps ST41 to ST44 is executed. In the first control, the controller (100) closes the utilization-side shut-off valve (43) in step ST42 and closes the heat-source-side shut-off valve (26) in step ST43 while continuously operating the compressor (22) in step ST41. As a result, the pump-down action is executed in step ST44. In the pump-down action, as illustrated in FIG. 3, the refrigerant on the secondary side of the utilization-side shut-off valve (43) in the utilization-side circuit (45) is sucked by the compressor (22), and is sent to the heat-source-side circuit (20a). The refrigerant discharged from the compressor (22) is collected in the receiver (25). Performing the pump-down operation can prevent the liquid refrigerant from accumulating in the utilization-side circuit (45), specifically, inside of the internal heat exchanger (42).

Next, in step ST45, the controller (100) determines whether or not a condition for stopping the compressor (22) is satisfied. Examples of the stopping condition include a condition indicating that the low pressure is lower than a predetermined value, a condition indicating that the high pressure is higher than a predetermined value, and a condition that the execution time of the first control exceeds a predetermined time.

If the stopping condition in step ST45 is satisfied, the controller (100) executes a third control to stop the compressor (22) in step ST46. Next, in step ST47, the controller (100) starts counting of the protection timer of the compressor (22) from when the compressor (22) is stopped. The controller (100) prohibits operation of the compressor (22) until the count of the protection timer of the compressor (22) exceeds the predetermined value, that is, until the condition in step ST17 in FIG. 4 is satisfied. In other words, the controller (100) prohibits the restart of operation of the compressor (22) for a predetermined first period after the third control.

In this embodiment, after the first control and the third control, the controller (100) executes the second control for determining whether the shut-off valves (26, 43) are abnormal, based on the pressure of the refrigerant in the refrigerant circuit (10). The second control includes processes from step ST48 to step ST53.

In step ST48, the controller (100) determines whether or not an abnormality condition for the utilization-side shut-off valve (43) is satisfied. Specifically, in step ST48, the controller (100) determines whether or not the first change amount (ΔP1) indicating a change in low pressure is greater than a predetermined value α. The first change amount (ΔP1) is the difference obtained by subtracting a first low pressure (LP1) from a second low pressure (LP2). The first low pressure (LP1) is a low pressure immediately after the compressor (22) is stopped in the third control. The second low pressure (LP2) is a low pressure after a predetermined time (e.g., two minutes) from when the first low pressure (LP1) was detected. If the utilization-side shut-off valve (43) does not operate normally and is not fully closed, the first change amount (ΔP1), i.e., the rate of increase in low pressure, increases. Thus, when the condition in step ST48 is satisfied, the controller (100) determines in step ST51 that the utilization-side shut-off valve (43) is abnormal.

In step ST49, the controller (100) determines whether or not an abnormality condition for the heat-source-side shut-off valve (26) is satisfied. Specifically, in step ST49, the controller (100) determines whether or not the second change amount (ΔP2) indicating a change in high pressure is greater than a predetermined value β. The second change amount (ΔP2) is the difference obtained by subtracting a first high pressure (HP1) from a second high pressure (HP2). The first high pressure (HP1) is a high pressure immediately after the compressor (22) is stopped. The second high pressure (HP2) is a high pressure after a predetermined time (e.g., two minutes) from when the first high pressure (HP1) was detected. If the heat-source-side shut-off valve (26) does not operate normally and is not fully closed, the second change amount (ΔP2), i.e., the rate of decrease in the high pressure, increases. Thus, if the condition in step ST49 is satisfied, the controller (100) determines in step ST52 that the heat-source-side shut-off valve (26) is abnormal.

If the abnormality conditions are not satisfied in step ST48 and step ST49, the controller (100) determines in step ST53 that the shut-off valves (26, 43) are not abnormal. Next, in step ST54, the third storage (133) stores the result of determination as to whether the shut-off valve (26, 43) is abnormal as a determination history.

In the determination action, in step ST55, the controller (100) resets the number of acquisitions N of the thermo-off signal (first signal). In other words, the controller (100) sets the number of acquisitions to zero each time the determination action is executed. When the determination action ends, step ST16 to step ST18 in FIG. 4 are executed, and normal operation is performed again.

By handling the operation unit (131), the operator can check the first information including the determination history stored in the third storage (133) on the screen of the display (132). As shown in FIG. 6, the screen (D) of the display (132) shows, as the first information, the type of the shut-off valve (26, 43), that the shut-off valve (26, 43) is abnormal, and the date and time of the occurrence of the abnormality. The first information displayed by the display (132) may include the date and time of the execution of the abnormality determination, the fact that the shut-off valve (26, 43) is normal, the cumulative number of times of abnormality of the shut-off valve (26, 43), and the cause of the abnormality that can be estimated according to the pressure or the like.

(9-1)
The controller (100) executes the determination action in response to acquisition of the first signal for setting the utilization unit (40) to the thermo-off state. In the determination action, the controller (100) executes the first control to close the shut-off valve (26, 43) during operation of the compressor (22) and the second control to determine, after the first control, whether the shut-off valve (26, 43) is abnormal based on the pressure or temperature of the refrigerant in the refrigerant circuit (10).

Since the shut-off valves (26, 43) are closed in the determination action, normal operation cannot be performed until the end of the determination as to whether the shut-off valves (26, 43) are abnormal. Therefore, for example, when the determination action is executed during normal operation, the air conditioning of the target space (S) is impaired. In particular, in the refrigeration cycle apparatus (1) (cooling apparatus) that cools the internal air of the internal space (S), the quality of stored items in the internal space (S) is impaired if the temperature of the inside air increases due to the determination action.

It is conceivable that the determination action is performed while the refrigeration cycle apparatus (1) is stopped. However, if the determination action is performed while the compressor (22) is operated while the refrigeration cycle apparatus (1) is stopped, power of the compressor (22) is unnecessarily consumed. In addition, in order to perform the determination based on the high pressure or the low pressure, it is necessary to secure the high and low differential pressures, and time is consumed. Furthermore, the refrigeration cycle apparatus (1) that cools the internal air of the internal space (S) basically performs the cooling operation at all times, and thus rarely stops. This reduces the frequency of determining the abnormality of the shut-off valve (26, 43).

In this embodiment, in view of such problems, the determination action is performed in response to acquisition of the thermo-off signal (first signal). At this timing, the temperature of the internal space (S) is close to the target temperature; therefore, the required temperature for the internal space (S) can be achieved even when the determination action is executed. Since the controller (100) frequently acquires a thermo-off signal, the frequency of the determination action for the shut-off valves (26, 43) can be sufficiently secured. It is not necessary to perform the determination action while the refrigeration cycle apparatus (1) is stopped, and unnecessary power and time are not consumed.

(9-2)
In the determination action, the controller (100) executes the third control to stop the compressor (22) before the second control. By stopping the compressor (22), changes in high pressure and the low pressure can be reduced. As a result, the high pressure and the low pressure are less likely to vary with the operation of the compressor (22); therefore, the accuracy of determination as to whether the shut-off valves (26, 43) are abnormal based on these pressures can be improved.

(9-3)
The controller (100) determines whether the shut-off valve (26, 43) is abnormal based on a change in high pressure of the refrigerant circuit (10) or on a change in low pressure of the refrigerant circuit (10). Since changes in high pressure and low pressure become large when the shut-off valve (26, 43) is not fully closed, the accuracy of determination as to whether the shut-off valve (26, 43) is abnormal can be improved.

(9-4)
The controller (100) prohibits the restart of operation of the compressor (22) for the predetermined first period after the third control. Specifically, the controller (100) prohibits operation of the compressor (22) for the first period until the count of the protection timer of the compressor (22) is satisfied. Thus, the compressor (22) can be protected.

The controller (100) determines, during the first period, whether the shut-off valve (26, 43) is abnormal by the second control. The time of the second control is two minutes, for example, and the time of count-up of the protection timer of the compressor is five minutes. Thus, the first period in which the compressor (22) is protected can be used for the determination of the state of the shut-off valves (26, 43).

(9-5)
The controller (100) includes the third storage (133) configured to store the determination result of the determination action as the determination history. The refrigeration cycle apparatus (1) includes the display (132) configured to display the determination history stored in the third storage (133). Thus, the operator can easily recognize the result of determination as to whether the shut-off valve (26, 43) is abnormal, and can take some measures.

(9-6)
The controller (100) performs the determination action each time the number of acquisitions of the first signal, which is the thermo-off signal, reaches a predetermined number equal to or greater than two. In other words, the controller (100) does not perform the determination action each time the first signal, which is the thermo-off signal, is acquired. This can reduce the amount of data relating to the determination history stored in the third storage (133).

(9-7)
The heat-source-side circuit (20a) includes the receiver (25) configured to store the refrigerant. In the first control, the controller (100) controls the refrigerant circuit (10) such that the refrigerant in the utilization-side circuit (45) is sent to the receiver (25). Thus, the refrigerant in the utilization-side circuit (45) can be collected in the receiver (25) during the determination action. As a result, when the operation of the compressor (22) is restarted thereafter, it is possible to prevent the liquid refrigerant from being sucked into the compressor (22).

The foregoing embodiment may be modified as the following variations. In the following description, the differences from the above embodiment will be described.

As shown in FIG. 7, a first variation is a refrigeration cycle system (150) including a first refrigeration cycle apparatus (1A) and a second refrigeration cycle apparatus (1B). The configurations of the first refrigeration cycle apparatus (1A) and the second refrigeration cycle apparatus (1B) are basically the same as the configuration of the refrigeration cycle apparatus (1) of the embodiment. A controller (100) of the refrigeration cycle system (150) is used in common by the first refrigeration cycle apparatus (1A) and the second refrigeration cycle apparatus (1B). The controller (100) may be provided for each of the first refrigeration cycle apparatus (1A) and the second refrigeration cycle apparatus (1B). A cooling unit (40) of the first refrigeration cycle apparatus (1A) and a cooling unit (40) of the second refrigeration cycle apparatus (1B) are disposed in the same target space (e.g., the internal space (S)) to cool the air in the same internal space (S). The cooling unit (40) of the first refrigeration cycle apparatus (1A) and the cooling unit (40) of the second refrigeration cycle apparatus (1B) may be disposed in different target spaces. In the first variation, the controller (100) executes the same control and the same determination action as those of the embodiment in both the first refrigeration cycle apparatus (1A) and the second refrigeration cycle apparatus (1B).

As shown in FIG. 8, a refrigeration cycle apparatus (1) of a second variation is a multi-type refrigeration cycle apparatus having a plurality of cooling units (40) that include a first cooling unit (40A) and a second cooling unit (40B). Utilization-side circuits include: a first utilization-side circuit (45A) including a first internal heat exchanger (42A) that is a first utilization-side heat exchanger; and a second utilization-side circuit (45B) including a second internal heat exchanger (42B) that is a second utilization-side heat exchanger. Refrigerant leakage sensors include: a first refrigerant leakage sensor (70A) configured to detect the leakage of the refrigerant from the first utilization-side circuit (45A); and a second refrigerant leakage sensor (70B) configured to detect the leakage of the refrigerant from the second utilization-side circuit (45B).

Shut-off valves include: a first internal expansion valve (43A) configured to shut off the flow of the refrigerant from the heat-source-side circuit (20a) to the first utilization-side circuit (45A); and a second internal expansion valve (43B) configured to shut off the flow of the refrigerant from the heat-source-side circuit (20a) to the second utilization-side circuit (45B). The shut-off valves further include a heat-source-side shut-off valve (26) similarly to the embodiment. The first internal expansion valve (43A) is a first utilization-side shut-off valve provided on the liquid side of the first utilization-side heat exchanger (42A) in the first utilization-side circuit (45A). The second internal expansion valve (43B) is a second utilization-side shut-off valve provided on the liquid side of the second internal heat exchanger (42B) in the second utilization-side circuit (45B).

When the first refrigerant leakage sensor (70A) detects leakage of the refrigerant, the controller (100) closes the first internal expansion valve (43A) and the heat-source-side shut-off valve (26). When the second refrigerant leakage sensor (70B) detects leakage of the refrigerant, the controller (100) closes the second internal expansion valve (43B) and the heat-source-side shut-off valve (26). The controller (100) may close the first internal expansion valve (43A), the second internal expansion valve (43B), and the heat-source-side shut-off valve (26) when either the first refrigerant leakage sensor (70A) or the second refrigerant leakage sensor (70B) detects leakage of the refrigerant.

A first internal temperature sensor (64A) and a second internal temperature sensor (64B) are provided in the internal space (S). The first internal temperature sensor (64A) corresponds to the first cooling unit (40A), and the second internal temperature sensor (64B) corresponds to the second cooling unit (40B).

When the difference (ΔT1) between a first internal temperature (Tr1) detected by the first internal temperature sensor (64A) and a target temperature (Ts) is less than a predetermined first value (T1), the controller (100) acquires a first signal (hereinafter referred to as the "first thermo-off signal") for setting the first cooling unit (40A) to the thermo-off state. When the difference (ΔT2) between a second internal temperature (Tr2) detected by the second internal temperature sensor (64B) and the target temperature (Ts) is less than the predetermined first value (T1), the controller (100) acquires a first signal (hereinafter referred to as the "second thermo-off signal") for setting the second cooling unit (40B) to the thermo-off state. In the normal operation, the controller (100) sets the first cooling unit (40A) to the thermo-off state when the controller (100) acquires the first thermo-off signal. Specifically, the controller (100) closes the first internal expansion valve (43A). In the normal operation, the controller (100) sets the second cooling unit (40B) to the thermo-off state when the controller (100) acquires the second thermo-off signal. Specifically, the controller (100) closes the second internal expansion valve (43B). The controller (100) stops the first cooling unit (40A) and the second cooling unit (40B) when it acquires the first thermo-off signal and the second thermo-off signal. Specifically, the controller (100) stops the compressor (22). As described above, in the second variation, the controller (100) performs individual thermo-off control that sets part of the plurality of cooling units (40A, 40B) to the thermo-off state and all-units thermo-off control that sets all the cooling units (40A, 40B) to the thermo-off state.

As shown in FIG. 9, in the normal operation, the controller (100) determines whether or not a determination action should be executed. Specifically, if the controller (100) acquires only the first thermo-off signal ("YES" in step ST72), the controller (100) executes a first individual thermo-off control for setting only the first cooling unit (40A) to the thermo-off state in step ST73. If the controller (100) acquires only the second thermo-off signal ("YES" in step ST74), the controller (100) executes a second individual thermo-off control for setting only the second cooling unit (40B) to the thermo-off state in step ST75.

If the controller (100) acquires the first thermo-off signal and the second thermo-off signal at the same time ("YES" in step ST76), the process proceeds to step ST77. If the number Na of simultaneous acquisitions of both of these signals has not reached a predetermined number Ns ("NO" in step ST77), the controller (100) executes the all-units thermo-off control in step ST78. If the number Na of simultaneous acquisitions of both of these signals has reached the predetermined number Ns ("YES" in step ST77), the controller (100) executes the determination action in step ST79.

The determination action of the second variation is basically the same as the determination action in FIG. 5 of the embodiment. However, in the first control of the second variation, the controller (100) closes the first utilization-side shut-off valve (first internal expansion valve (43A)), the second utilization-side shut-off valve (second internal expansion valve (43B)), and the heat-source-side shut-off valve (26). In the second control of the second variation, the controller (100) determines whether each of the first internal expansion valve (43A), the second internal expansion valve (43B), and the heat-source-side shut-off valve (26) is abnormal. When the first internal expansion valve (43A) and the second internal expansion valve (43B) do not operate normally, the behavior of pressure and temperature in the refrigerant circuit (10) differs from that in a case where these valves operate normally. Thus, the controller (100) can determine whether the first utilization-side shut-off valve (43A) and the second internal expansion valve (43B) are abnormal, based on the pressure and temperature of the refrigerant in the refrigerant circuit (10). The controller (100) determines whether the heat-source-side shut-off valve (26) is abnormal in a similar manner to that in the embodiment.

As shown in FIG. 10, a refrigeration cycle apparatus (1) of a third variation is a multi-type refrigeration cycle apparatus having a plurality of cooling units (40) that include a first cooling unit (40A) and a second cooling unit (40B).

The third variation is different from the second variation in the configurations of the cooling unit (40) and the utilization-side circuit (45). Specifically, the first utilization-side circuit (45A) includes a first internal expansion valve (43A) (hereinafter also referred to as the "first utilization-side liquid shut-off valve (43A)"), and a first utilization-side gas shut-off valve (46A). The first utilization-side liquid shut-off valve (43A) and the first utilization-side gas shut-off valve (46A) constitute first utilization-side shut-off valves. The second utilization-side circuit (45B) includes a second internal expansion valve (43B) (hereinafter also referred to as the "second utilization-side liquid shut-off valve (43B)"), and a second utilization-side gas shut-off valve (46B). The second utilization-side liquid shut-off valve (43B) and the second utilization-side gas shut-off valve (46B) constitute second utilization-side shut-off valves. The first utilization-side liquid shut-off valve (43A) is provided on the liquid side of the first internal heat exchanger (42A) in the first utilization-side circuit (45A). The second utilization-side liquid shut-off valve (43B) is provided on the liquid side of the second internal heat exchanger (42B) in the second utilization-side circuit (45B). The first utilization-side gas shut-off valve (46A) is provided on the gas side of the first internal heat exchanger (42A) in the first utilization-side circuit (45A). The second utilization-side gas shut-off valve (46B) is provided on the gas side of the second internal heat exchanger (42B) in the second utilization-side circuit (45B). The first utilization-side gas shut-off valve (46A) and the second utilization-side gas shut-off valve (46B) are configured as, for example, electronic expansion valves.

A first bypass flow path (47A) that bypasses the first utilization-side gas shut-off valve (46A) is connected to the first utilization-side circuit (45A). One end of the first bypass flow path (47A) is connected between the first utilization-side gas shut-off valve (46A) and the gas end of the first internal heat exchanger (42A). The other end of the first bypass flow path (47A) is connected between the first utilization-side gas shut-off valve (46A) and the gas end of the first utilization-side circuit (45A). A first check valve (48A) is provided in the first bypass flow path (47A). The first check valve (48A) allows the refrigerant to flow from the one end toward the other end of the first bypass flow path (47A) and prohibits the refrigerant flow in the opposite direction.

A second bypass flow path (47B) that bypasses the second utilization-side gas shut-off valve (46B) is connected to the second utilization-side circuit (45B). One end of the second bypass flow path (47B) is connected between the second utilization-side gas shut-off valve (46B) and the gas end of the second internal heat exchanger (42B). The other end of the second bypass flow path (47B) is connected between the second utilization-side gas shut-off valve (46B) and the gas end of the second utilization-side circuit (45B). A second check valve (48B) is provided in the second bypass flow path (47B). The second check valve (48B) allows the refrigerant to flow from the one end toward the other end of the second bypass flow path (47B) and prohibits the refrigerant flow in the opposite direction.

The first utilization-side circuit (45A) is provided with a first utilization-side pressure sensor (65A) between the first internal expansion valve (43A) and the first utilization-side gas shut-off valve (46A). The first utilization-side pressure sensor (65A) detects, as a first utilization-side pressure (Pu1), a pressure of a space in the first utilization-side circuit (45A) which is shut off by the first utilization-side gas shut-off valve (46A) and the first utilization-side liquid shut-off valve (43A). The second utilization-side circuit (45B) is provided with a second utilization-side pressure sensor (65B) between the second internal expansion valve (43B) and the second utilization-side gas shut-off valve (46B). The second utilization-side pressure sensor (65B) detects, as a second utilization-side pressure (Pu2), a pressure of a space in the second utilization-side circuit (45B) which is shut off by the second utilization-side gas shut-off valve (46B) and the second utilization-side liquid shut-off valve (43B).

When the first refrigerant leakage sensor (70A) detects leakage of the refrigerant, the controller (100) closes the first internal expansion valve (43A), the first utilization-side gas shut-off valve (46A), and the heat-source-side shut-off valve (26). When the second refrigerant leakage sensor (70B) detects leakage of the refrigerant, the controller (100) closes the second internal expansion valve (43B), the second utilization-side gas shut-off valve (46B), and the heat-source-side shut-off valve (26). The controller (100) may close the first internal expansion valve (43A), the first utilization-side gas shut-off valve (46A), the second internal expansion valve (43B), the second utilization-side gas shut-off valve (46B), and the heat-source-side shut-off valve (26) when either the first refrigerant leakage sensor (70A) or the second refrigerant leakage sensor (70B) detects leakage of the refrigerant.

When the difference (ΔT1) between a first internal temperature (Tr1) detected by the first internal temperature sensor (64A) and a target temperature (Ts) is less than a predetermined first value (T1), the controller (100) acquires a first signal (hereinafter referred to as the "first thermo-off signal") for setting the first cooling unit (40A) to the thermo-off state. When the difference (ΔT2) between a second internal temperature (Tr2) detected by the second internal temperature sensor (64B) and the target temperature (Ts) is less than the predetermined first value (T1), the controller (100) acquires a first signal (hereinafter referred to as the "second thermo-off signal") for setting the second cooling unit (40B) to the thermo-off state. In the normal operation, the controller (100) sets the first cooling unit (40A) to the thermo-off state when the controller (100) acquires the first thermo-off signal. Specifically, the controller (100) closes the first internal expansion valve (43A). The controller (100) may close the first utilization-side gas shut-off valve (46A). In the normal operation, the controller (100) sets the second cooling unit (40B) to the thermo-off state when the controller (100) acquires the second thermo-off signal. Specifically, the controller (100) closes the second internal expansion valve (43B). The controller (100) may close the second utilization-side gas shut-off valve (46B). The controller (100) stops the first cooling unit (40A) and the second cooling unit (40B) when it acquires the first thermo-off signal and the second thermo-off signal. Specifically, the controller (100) stops the compressor (22). As described above, in the third variation, the controller (100) performs individual thermo-off control that sets part of the plurality of cooling units (40A, 40B) to the thermo-off state and all-units thermo-off control that sets all the cooling units (40A, 40B) to the thermo-off state.

As shown in FIG. 11, in the normal operation, the controller (100) determines whether or not a determination action should be executed. Specifically, if the controller (100) acquires only the first thermo-off signal ("YES" in step ST82), the process proceeds to step ST83. If the number of acquisitions N1 of the first thermo-off signal has not reached a predetermined number Ns ("NO" in step ST83), the controller (100) executes the first individual thermo-off control in step ST84. If the number of acquisitions N1 of the first thermo-off signal has reached the predetermined number Ns ("YES" in step ST83), the controller (100) executes a first determination action in step ST85.

If the controller (100) acquires only the second thermo-off signal ("YES" in step ST86), the process proceeds to step ST87. If the number of acquisitions N2 of the second thermo-off signal has not reached the predetermined number Ns ("NO" in step ST87), the controller (100) executes the second individual thermo-off control in step ST88. If the number of acquisitions N2 of the second thermo-off signal has reached the predetermined number Ns ("YES" in step ST87), the controller (100) executes a second determination action in step ST89.

If the controller (100) acquires the first thermo-off signal and the second thermo-off signal at the same time ("YES" in step ST90), the process proceeds to step ST91. If the number Na of simultaneous acquisitions of both of these signals has not reached a predetermined number Ns ("NO" in step ST91), the controller (100) executes the all-units thermo-off control in step ST92. If the number Na of simultaneous acquisitions of both of these signals has reached the predetermined number Ns ("YES" in step ST91), the controller (100) executes a third determination action in step ST93.

The first determination action is a determination action associated with the first thermo-off signal corresponding to the first cooling unit (40A). During the first determination action, the second cooling unit (40B) is maintained in a thermo-on state. Thus, a cooling action (air-conditioning action) for the internal space (S) is continuously executed by the second cooling unit (40B). The controller (100) opens the second utilization-side liquid shut-off valve (43B) and the second utilization-side gas shut-off valve (46B) of the second cooling unit (40B), and adjusts the opening degrees of these valves.

In the first control in the first determination action shown in FIG. 12, the controller (100) operates the compressor (22) continuously in step ST101, closes the first utilization-side liquid shut-off valve (43A) in step ST102, and closes the first utilization-side gas shut-off valve (46A) in step ST103. Next, when a predetermined time has elapsed in step ST104, the controller (100) executes the second control.

In the second control, the controller (100) determines whether the first utilization-side liquid shut-off valve (43A) and the first utilization-side gas shut-off valve (46A) are abnormal. In step ST105, the controller (100) determines whether the first utilization-side liquid shut-off valve (43A) is abnormal, based on the amount of change in pressure difference between the upstream side and the downstream side of the first utilization-side liquid shut-off valve (43A). Specifically, in step ST105, the controller (100) determines whether the amount of change in a first liquid-side pressure difference (ΔPl1) is greater than a predetermined value A. The first liquid-side pressure difference (ΔPl1) is the difference (Pa - Pu1) between the liquid pressure (Pa) detected by the liquid-pressure sensor (63) and the first utilization-side pressure (Pu1) detected by the first utilization-side pressure sensor (65A). If the amount of change in the first liquid-side pressure difference (ΔPl1) in the predetermined time is large, the controller (100) determines, in step ST106, that the first utilization-side liquid shut-off valve (43A) is abnormal. For example, the predetermined time corresponds to a delay time in step ST104.

In step ST107, the controller (100) determines whether the first utilization-side gas shut-off valve (46A) is abnormal, based on the amount of change in pressure difference between the upstream side and the downstream side of the first utilization-side gas shut-off valve (46A). Specifically, in step ST107, the controller (100) determines whether the amount of change in a first gas-side pressure difference (ΔPg1) is greater than a predetermined value B. The first gas-side pressure difference (ΔPg1) is the difference (LP - Pu1) between the low pressure (LP) detected by the low-pressure sensor (62) and the first utilization-side pressure (Pu1) detected by the first utilization-side pressure sensor (65A). If the amount of change in the first gas-side pressure difference (ΔPg1) in the predetermined time is large, the controller (100) determines, in step ST108, that the first utilization-side gas shut-off valve (46A) is abnormal. For example, the predetermined time corresponds to a delay time in step ST104.

If the conditions in step ST105 and step ST107 are not satisfied, the controller (100) determines, in step ST109, that there is no abnormality. Next, the controller (100) stores the determination history in step ST110, and resets the number of acquisitions N1 in step ST111.

The second determination action is a determination action associated with the second thermo-off signal corresponding to the second cooling unit (40B). During the second determination action, the first cooling unit (40A) is maintained in the thermo-on state. Thus, a cooling action (air-conditioning action) for the internal space (S) is continuously executed by the first cooling unit (40A). The controller (100) opens the first utilization-side liquid shut-off valve (43A) and the first utilization-side gas shut-off valve (46A) of the first cooling unit (40A), and adjusts the opening degrees of these valves.

In the first control in the second determination action shown in FIG. 13, the controller (100) operates the compressor (22) continuously in step ST121, closes the second utilization-side liquid shut-off valve (43B) in step ST122, and closes the second utilization-side gas shut-off valve (46B) in step ST123. Next, when a predetermined time has elapsed in step ST124, the controller (100) executes the second control.

In the second control, the controller (100) determines whether the second utilization-side liquid shut-off valve (43B) and the second utilization-side gas shut-off valve (46B) are abnormal. In step ST125, the controller (100) determines whether the second utilization-side liquid shut-off valve (43B) is abnormal, based on the amount of change in pressure difference between the upstream side and the downstream side of the second utilization-side liquid shut-off valve (43B). Specifically, in step ST125, the controller (100) determines whether the amount of change in a second liquid-side pressure difference (ΔPl2) is greater than the predetermined value A. The second liquid-side pressure difference (ΔPl2) is the difference (Pa - Pu2) between the liquid pressure (Pa) detected by the liquid-pressure sensor (63) and the second utilization-side pressure (Pu2) detected by the second utilization-side pressure sensor (65B). If the amount of change in the second liquid-side pressure difference (ΔPl2) in the predetermined time is large, the controller (100) determines, in step ST126, that the second utilization-side liquid shut-off valve (43B) is abnormal. For example, the predetermined time corresponds to a delay time in step ST124.

In step ST127, the controller (100) determines whether the second utilization-side gas shut-off valve (46B) is abnormal, based on the amount of change in pressure difference between the upstream side and the downstream side of the second utilization-side gas shut-off valve (46B). Specifically, in step ST127, the controller (100) determines whether the amount of change in a second gas-side pressure difference (ΔPg2) is greater than the predetermined value B. The second gas-side pressure difference (ΔPg2) is the difference (LP - Pu2) between the low pressure (LP) detected by the low-pressure sensor (62) and the second utilization-side pressure (Pu2) detected by the second utilization-side pressure sensor (65B). If the amount of change in the second gas-side pressure difference (ΔPg2) in the predetermined time is large, the controller (100) determines, in step ST128, that the second utilization-side gas shut-off valve (46B) is abnormal. For example, the predetermined time corresponds to a delay time in step ST124.

If the conditions in step ST125 and step ST127 are not satisfied, the controller (100) determines, in step ST129, that there is no abnormality. Next, the controller (100) stores the determination history in step ST130, and resets the number of acquisitions N2 in step ST131.

The third determination action is a determination action associated with the first thermo-off signal and the second thermo-off signal. The third determination action sets the first cooling unit (40A) and the second cooling unit (40B) to a substantially thermo-off state. The third determination action differs from the determination action of the embodiment shown in FIG. 5 in details of the first control and the second control.

As shown in FIG. 14, in the first control, the controller (100) operates the compressor (22) continuously in step ST141, closes the first utilization-side liquid shut-off valve (43A) in step ST142, closes the first utilization-side gas shut-off valve (46A) in step ST143, closes the second utilization-side liquid shut-off valve (43B) in step ST144, closes the second utilization-side gas shut-off valve (46B) in step ST145, and closes the heat-source-side shut-off valve (26) in step ST146.

As shown in FIG. 15, in the second control, the controller (100) determines whether the first utilization-side liquid shut-off valve (43A), the first utilization-side gas shut-off valve (46A), the second utilization-side liquid shut-off valve (43B), the second utilization-side gas shut-off valve (46B), and the heat-source-side shut-off valve (26) are abnormal. Determinations in step ST151 to step ST158 are the same as those of the first determination action or the second determination action, and thus the description thereof will be omitted.

In step ST159, the controller (100) determines whether the heat-source-side shut-off valve (26) is abnormal, based on the amount of change in pressure difference between the upstream side and the downstream side of the heat-source-side shut-off valve (26). Specifically, in step ST159, the controller (100) determines whether the amount of change in a heat-source-side pressure difference (ΔPh) is greater than a predetermined value. The heat-source-side pressure difference (ΔPh) is the difference (HP - Pa) between the high pressure (HP) detected by the high-pressure sensor (61) and the liquid pressure (Pa) detected by the liquid-pressure sensor (63). If the amount of change in the heat-source-side pressure difference (ΔPh) in the predetermined time is large, the controller (100) determines, in step ST160, that the heat-source-side shut-off valve (26) is abnormal. In the second control of the third determination action, a determination as to whether the heat-source-side shut-off valve (26) is abnormal may be omitted.

The above embodiment and variations may have the following configurations.

The refrigeration cycle apparatus (1) may be an air conditioner that cools or heats an indoor space, which is the target space (S). The refrigeration cycle apparatus (1) does not have to be a stationary refrigeration cycle apparatus, and may be a movable refrigeration cycle apparatus that cools an internal space of a transport container, for example.

In the determination action, the controller (100) may determine whether the shut-off valves (26, 43) are abnormal based on the pressure and temperature of the refrigerant in the refrigerant circuit (10), while operating the compressor (22). This is because, even when the compressor (22) is operating, if the shut-off valves (26, 43) do not operate normally, the pressure and temperature of the refrigerant behave differently from normal.

In the first control, the controller (100) may reduce the opening degrees of the shut-off valves (26, 43) to predetermined opening degrees without fully closing them. For example, the controller (100) reduces the opening degree of the utilization-side shut-off valve (43) by a predetermined pulse. In this case as well, if the utilization-side shut-off valve (43) does not operate normally, the opening degree of the utilization-side shut-off valve (43) cannot be reduced to a target opening degree, and the pressure and temperature of the refrigerant behave differently from normal. Thus, it is possible to determine, through the second control, whether the utilization-side shut-off valve (43) is abnormal.

The refrigeration cycle apparatus (1) may include a shut-off valve only in the utilization-side circuit (45) without including a shut-off valve in the heat-source-side circuit (20a). The refrigeration cycle apparatus (1) may include a shut-off valve only in the heat-source-side circuit (20a) without including a shut-off valve in the utilization-side circuit (45).

The notification unit (132) does not have to be a display, and may be a notification unit that provides notification of the result of the determination action, a sound generator that outputs the result of the determination action by sound, or a light generator that outputs the result of the determination action by light. The notification unit includes, for example, a notification by email or a notification on an application, and transmits information on the result of the determination action to an operator via wired or wireless communication.

When it is determined that the shut-off valve (26, 43) is abnormal, the display (132) may automatically indicate that the shut-off valve (26, 43) is abnormal, without waiting for the operator's operation. In this case, it is preferable that the display (132) displays characters, icons, pictures, or the like indicating an abnormality of the shut-off valve (26, 43) on an initial operation screen.

The controller (100) may be provided in a terminal device connected to the refrigeration cycle apparatus (1) via wired or wireless communication. Examples of the terminal device include a server, a central monitor, and a communication terminal for the operator. Examples of the communication terminal include a smartphone, a tablet, and a personal computer.

The shut-off valves (26, 43) may each be configured as an electromagnetic on-off valve, an electric ball valve, a three-way valve, or a four-way switching valve.

The controller (100) may perform a determination action upon acquiring a thermo-off signal when the condition that a predetermined set period has elapsed is satisfied, and may perform a normal thermo-off action upon acquiring a thermo-off signal when this condition is not satisfied.

The thermo-off action is not necessarily the same as steps ST41 to ST47 of the determination action. The thermo-off action may be any action as long as it substantially stops the air-conditioning function for the target space (S), such as stopping the compressor (22), fully closing a utilization-side expansion valve, setting the opening degree of the utilization-side expansion valve to a very small opening degree, stopping a utilization-side fan, and setting the number of rotations of the utilization-side fan to a minimum number of rotations.

Heating medium side elements of the heat-source-side circuit (20a) may include, for example, a subcooling heat exchanger, an oil separator, and a gas venting circuit of the receiver (25). Two or more compressors may be provided for the heat-source-side circuit (20a) in series or in parallel. Two or more outdoor heat exchangers (23) may be provided for the heat-source-side circuit (20a) in series or in parallel.

When a predetermined time (e.g., one month) has elapsed since the execution of the previous determination action, the controller (100) may forcibly execute a determination action irrespective of the presence or absence of the first signal.

The controller (100) may be configured to be able to change control related to the determination action depending on the refrigeration cycle apparatus (1) and the refrigeration cycle system (150) described in the embodiment, the first variation, the second variation, and the third variation. For example, a user selects, by operating the operation unit (131), whether the target refrigeration cycle apparatus (1) is of the pair type of the embodiment, the refrigeration cycle system (150) of the first variation, of a multi-type of the second variation, or of a multi-type of the third variation. The controller (100) executes a control mode of the determination action suitable for the target in accordance with this selection.

A control method according to the present disclosure includes the steps of any of the above-described embodiment and variations.

A program according to the present disclosure is used to cause a computer to execute a control method including the steps of any of the above-described embodiment and variations.

While the embodiment and variations thereof have been described above, it will be understood that various changes in form and details may be made without departing from the spirit and scope of the claims. The embodiment, the variations thereof, and the other embodiments may be combined appropriately and replaced with each other without deteriorating intended functions of the present disclosure.

The ordinal numbers such as "first," "second," "third," ..., described above are used to distinguish the terms to which these expressions are given, and do not limit the number and order of the terms.

As can be seen from the foregoing description, the present disclosure is useful for a refrigeration cycle apparatus, a control method, and a program.

1

Refrigeration Cycle Apparatus

10

Refrigerant Circuit

20a

Heat-Source-Side Circuit

22

Compressor

23

Heat-Source-Side Heat Exchanger

25

Receiver

26

Heat-Source-Side Shut-Off Valve (Shut-Off Valve)

40

Cooling Unit (Utilization Unit)

40A

First Cooling Unit (First Utilization Unit)

40B

Second Cooling Unit (Second Utilization Unit)

42

Utilization-Side Heat Exchanger

42A

First Utilization-Side Heat Exchanger

42B

Second Utilization-Side Heat Exchanger

43

Internal Expansion Valve

43A

First Internal Expansion Valve (First Utilization-Side Liquid Shut-Off Valve)

43B

Second Internal Expansion Valve (Second Utilization-Side Liquid Shut-Off Valve)

45

Utilization-Side Circuit

45A

First Utilization-Side Circuit

45b

Second Utilization-Side Circuit

46A

First Utilization-Side Gas Shut-Off Valve

46B

Second Utilization-Side Gas Shut-Off Valve

70

Refrigerant Leakage Sensor

70A

First Refrigerant Leakage Sensor

70B

Second Refrigerant Leakage Sensor

100

Controller

132

Display

133

Third Storage (Storage)