Refrigeration cycle equipment

Abstract

This refrigeration cycle device comprises a compressor, a first heat exchanger, a pressure reducing device, a second heat exchanger, a storage tank unit that allows a refrigerant flowing through an interior thereof to pass or stores the refrigerant flowing through the interior thereof, a refrigerant pipeline forming a refrigerant circuit, and a control device, wherein: the storage tank unit includes pipelines that are provided in parallel, and includes, in one of the pipelines that are provided in parallel, a buffer tank for storing the refrigerant, a first gate valve positioned upstream of the buffer tank, and a second gate valve positioned downstream of the buffer tank; and if the refrigeration cycle device stops operating in a state in which the first gate valve and the second gate valve are maintained in a fully-closed state, the control device opens the first gate valve and the second gate valve.

Description

[Technical Field]

[0001] The present disclosure relates to a refrigeration cycle device that utilizes a refrigeration cycle. [Background technology]

[0002] Conventionally, a refrigeration cycle device is filled with a refrigerant to utilize the refrigeration cycle. In recent years, as concerns about global warming caused by chlorofluorocarbons and other issues have grown, there has been a desire to switch from refrigerants with high GWP (Global Warming Potential) to refrigerants with low GWP, and regulations on the types of refrigerants that can be used have become stricter. Refrigerant regulations are no exception for refrigeration cycle devices currently in use, and there is a desire to switch from currently used refrigerants to devices that are compatible with refrigerants with lower GWPs. Furthermore, there may be cases where refrigeration cycle devices to be used in the future are also desired to be compatible with refrigerants with even lower GWPs than the refrigerants currently in use.

[0003] When using a refrigerant with a low GWP, replacing the currently used refrigeration cycle equipment or other equipment requires excessive capital investment, including costs and construction time, which places a heavy burden on the user. To address this issue, a so-called retrofit approach has been proposed, in which the refrigerant sealed in the refrigeration cycle equipment is replaced with another refrigerant and the existing equipment is used. In retrofitting, depending on the physical properties of the replacement refrigerant, a refrigerant with a higher operating pressure than the refrigerant currently in use may be selected. Refrigerants with a low GWP often have physical properties that result in a higher operating pressure than the refrigerant currently in use.

[0004] Many refrigeration cycle devices are designed to accommodate the physical properties of the refrigerant currently in use, and when retrofitting to replace a refrigerant with one that has a higher operating pressure, there is a concern that the pressure inside the device may exceed the design pressure of the current device. Therefore, when using a refrigerant with a higher operating pressure, a refrigeration cycle device has been proposed that is equipped with a method of storing excess refrigerant in the refrigeration cycle during operation by providing a low-pressure receiver and a high-pressure receiver in the refrigerant circuit (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0005] [Patent Document 1] International Publication No. 2019 / 124140 Summary of the Invention [Problem to be solved by the invention]

[0006] The refrigeration cycle device in Patent Document 1 is said to prevent the pressure inside the device from exceeding the design pressure of the device by storing excess refrigerant in the refrigeration cycle during operation, but no structure or control has been proposed to prevent the pressure inside the device from exceeding the design pressure when operation is stopped.In particular, with the rise in temperature in recent years, the pressure inside the device may rise excessively due to heat entering from outside even when the device is stopped, and there is a concern that the pressure inside the device will exceed the design pressure of the device in the low-pressure circuit from the pressure reducer to the compressor in the refrigeration cycle.

[0007] The present disclosure is intended to solve the above-mentioned problems, and aims to provide a refrigeration cycle device in which the pressure inside the device does not exceed the design pressure of the device while the device is not operating. [Means for solving the problem]

[0008] The refrigeration cycle device according to the present disclosure is a refrigeration cycle device that utilizes a refrigeration cycle, and includes a compressor that compresses a refrigerant, a first heat exchanger that condenses the refrigerant discharged from the compressor, a pressure reducing device that reduces the pressure of the refrigerant flowing out of the first heat exchanger, a second heat exchanger that evaporates the refrigerant reduced in pressure by the pressure reducing device, a storage tank section that is provided between the pressure reducing device and an intake port of the compressor and that allows the refrigerant flowing therethrough to pass through or that stores the refrigerant flowing therethrough, and a storage tank section that connects the compressor, the first heat exchanger, the pressure reducing device, the second heat exchanger, and the storage tank section. The refrigerant cycle device includes a refrigerant piping that configures a refrigerant circuit, and a control device that controls each device provided in the refrigerant circuit. The storage tank section has piping that is provided in parallel with each other, and one of the piping that is provided in parallel has a buffer tank that stores refrigerant, a first gate valve located upstream of the buffer tank, and a second gate valve located downstream of the buffer tank. The control device opens the first gate valve and the second gate valve when the refrigeration cycle device stops operating while the compressor is driven and the first gate valve and the second gate valve are maintained in a fully closed state. The storage tank section has an upstream pipe and a downstream pipe connected to the refrigerant pipe, the first gate valve is provided so as to be located upstream of the buffer tank in the flow direction of the refrigerant flowing while the compressor is operating, and is a valve that allows the refrigerant to flow into the buffer tank when the valve is opened and prevents the refrigerant from flowing into the buffer tank when the valve is closed, and the second gate valve is provided so as to be located downstream of the buffer tank in the flow direction of the refrigerant flowing while the compressor is operating, and is a valve that prevents the refrigerant from flowing back into the buffer tank when the valve is closed, and is provided in parallel. The pipes are a first pipe and a second pipe that form a parallel circuit through which a refrigerant flows between an upstream pipe and a downstream pipe, the first pipe is provided to connect the upstream pipe and the downstream pipe, and the second pipe is provided with a first gate valve, a buffer tank, and a second gate valve, and the first pipe and the second pipe have one or more of the following configurations: a configuration in which the diameter of the second pipe located upstream of the buffer tank is larger than the diameter of the first pipe; and a configuration in which the position of the second pipe connected to the buffer tank is lower than the position of the first pipe. It is something.

[0009] The refrigeration cycle device according to the present disclosure is a refrigeration cycle device that utilizes a refrigeration cycle, and includes a compressor that compresses a refrigerant, a first heat exchanger that condenses the refrigerant discharged from the compressor, a pressure reducing device that reduces the pressure of the refrigerant flowing out of the first heat exchanger, a second heat exchanger that evaporates the refrigerant reduced in pressure by the pressure reducing device, a storage tank portion that is provided between the pressure reducing device and an intake port of the compressor and that allows the refrigerant flowing therethrough to pass through or that stores the refrigerant flowing therethrough, and a storage tank portion that connects the compressor, the first heat exchanger, the pressure reducing device, the second heat exchanger, and the storage tank portion. The storage tank section has piping arranged in parallel with one another, and one of the piping sections has a buffer tank for storing refrigerant, a first gate valve located upstream of the buffer tank, and a second gate valve which is a check valve located downstream of the buffer tank. The control device is configured to open the first gate valve when the refrigeration cycle device is stopped while the compressor is driven and the first gate valve is maintained in a fully closed state. The storage tank section has an upstream pipe and a downstream pipe connected to the refrigerant pipe, the first gate valve is provided so as to be located upstream of the buffer tank in the flow direction of the refrigerant flowing while the compressor is operating, and is a valve that allows the refrigerant to flow into the buffer tank when the valve is opened and prevents the refrigerant from flowing into the buffer tank when the valve is closed, the second gate valve is provided so as to be located downstream of the buffer tank in the flow direction of the refrigerant flowing while the compressor is operating and is a valve that prevents the refrigerant from flowing back into the buffer tank, and the pipes provided in parallel are The first pipe and the second pipe constitute a parallel circuit through which a refrigerant flows between an upstream pipe and a downstream pipe, the first pipe is provided to connect the upstream pipe and the downstream pipe, and the second pipe is provided with a first gate valve, a buffer tank, and a second gate valve, and the first pipe and the second pipe have one or more of the following configurations: a configuration in which the diameter of the second pipe located upstream of the buffer tank is larger than the diameter of the first pipe; and a configuration in which the position of the second pipe connected to the buffer tank is lower than the position of the first pipe. It is something. [Effects of the Invention]

[0010] The refrigeration cycle apparatus according to the present disclosure can, by control of the control device, release the pressure in the low-pressure piping between the pressure reducing device and the compressor to the buffer tank of the storage tank when the apparatus is shut down, even when a refrigerant with a high operating pressure is used after retrofitting. Therefore, the refrigeration cycle apparatus can prevent the pressure inside the apparatus from exceeding the design pressure of the apparatus when the apparatus is shut down. [Brief explanation of the drawings]

[0011] [Figure 1] 1 is a refrigerant circuit diagram of a refrigeration cycle device according to a first embodiment. [Figure 2] FIG. 4 is a refrigerant circuit diagram of a modified example of the refrigeration cycle device according to the first embodiment. [Figure 3] 2 is a functional block diagram showing an example of the configuration of the control device shown in FIG. 1. FIG. [Figure 4] 4 is a hardware configuration diagram showing an example of the configuration of the control device shown in FIG. 3. FIG. [Figure 5] 4 is a hardware configuration diagram showing another example of the configuration of the control device shown in FIG. 3. FIG. [Figure 6] 4 is a diagram showing the relationship between pressure [MPa] and elapsed time [s] of the refrigeration cycle device according to the first embodiment. FIG. [Figure 7] FIG. 3 is a flow chart showing an example of control of the refrigeration cycle device according to the first embodiment. [Figure 8] 3 is a conceptual diagram showing the relationship between a first pipe and a second pipe of the refrigeration cycle device according to the first embodiment. FIG. [Figure 9] FIG. 6 is a refrigerant circuit diagram of a refrigeration cycle device according to a second embodiment. [Figure 10] 10 is a functional block diagram showing an example of the configuration of the control device shown in FIG. 9. FIG. [Figure 11] FIG. 10 is a diagram showing the relationship between pressure [MPa] and elapsed time [s] in the refrigeration cycle device according to the second embodiment. [Figure 12] FIG. 10 is a flow chart showing an example of control of the refrigeration cycle device according to the second embodiment. [Figure 13]FIG. 10 is a refrigerant circuit diagram of a refrigeration cycle device according to a third embodiment. [Figure 14] 14 is a functional block diagram showing an example of the configuration of the control device shown in FIG. 13. FIG. [Figure 15] FIG. 10 is a flow chart showing an example of control of the refrigeration cycle device according to the third embodiment. [Figure 16] FIG. 10 is a refrigerant circuit diagram of a refrigeration cycle device according to a fourth embodiment. [Figure 17] 17 is a functional block diagram showing an example of the configuration of the control device shown in FIG. 16. FIG. [Figure 18] FIG. 10 is a flow chart showing an example of control of the refrigeration cycle device according to the fourth embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0012] Hereinafter, embodiments for carrying out the present disclosure will be described with reference to the drawings. Hereinafter, in the following drawings, including FIG. 1, components denoted with the same reference numerals are identical or equivalent, and are common throughout the following embodiments. In each embodiment, components that are identical or equivalent to those described in the preceding embodiment may be denoted with the same reference numerals, and their description may be omitted. The forms of components shown throughout the specification are merely examples and are not limited to the forms described in the specification. The following embodiments may be partially combined with each other, even if not specifically stated, as long as there is no particular problem with the combination.

[0013] Embodiment 1 [Configuration of refrigeration cycle device 100] Fig. 1 is a refrigerant circuit diagram of a refrigeration cycle apparatus 100 according to embodiment 1. Fig. 2 is a refrigerant circuit diagram of a modified example of the refrigeration cycle apparatus 100 according to embodiment 1. The refrigeration cycle apparatus 100 will be described with reference to Figs. 1 and 2. Solid arrows shown in Figs. 1 and 2 indicate the flow of refrigerant in the refrigeration cycle apparatus 100.

[0014] The refrigeration cycle device 100 is a device that utilizes a refrigeration cycle, and is, for example, a device used for refrigeration or air conditioning purposes, such as a refrigeration device such as a refrigerator, a refrigeration device such as a freezer, a vending machine, an air conditioner, or a hot water supply device.

[0015] The refrigeration cycle apparatus 100 includes a compressor 10, a first heat exchanger 20, a decompression device 30, a second heat exchanger 40, and a storage tank 50. The refrigeration cycle apparatus 100 also includes refrigerant piping 75 that configures a refrigerant circuit 70 by connecting the compressor 10, the first heat exchanger 20, the decompression device 30, the second heat exchanger 40, and the storage tank 50. The refrigeration cycle apparatus 100 also includes a control device 80 that controls each device that configures the refrigeration cycle apparatus 100.

[0016] (Compressor 10) The compressor 10 draws in low-temperature, low-pressure refrigerant through an intake port 10a, compresses the drawn refrigerant, and discharges high-temperature, high-pressure refrigerant from an outlet port 10b. The compressor 10 is equipped with an inverter device, and controls its capacity, which is the amount of refrigerant delivered per unit time, by changing its operating frequency. The operating frequency of the compressor 10 is controlled by a control device 80. For example, when the amount of heat exchange within the refrigerant circuit 70 is to be increased, the control device 80 increases the capacity of the compressor 10 and increases the amount of refrigerant circulating within the refrigerant circuit 70.

[0017] (1st heat exchanger 20) The first heat exchanger 20 exchanges heat between the air present around the first heat exchanger 20 and the refrigerant flowing inside the first heat exchanger 20. In the refrigeration cycle apparatus 100 shown in Fig. 1, the first heat exchanger 20 is a condenser. The first heat exchanger 20, which is a condenser, condenses the refrigerant discharged from the compressor 10. The first heat exchanger 20 dissipates heat from the refrigerant flowing inside the first heat exchanger 20 to the air present around the first heat exchanger 20, condensing the refrigerant.

[0018] (Decompression device 30) The pressure reducing device 30 reduces the pressure of the refrigerant flowing out of the first heat exchanger 20. The pressure reducing device 30 is, for example, an electronic expansion valve that can adjust the aperture of the throttle, and controls the pressure of the refrigerant flowing into the second heat exchanger 40 by adjusting the aperture of the valve. The aperture of the valve of the pressure reducing device 30 is controlled by the control device 80.

[0019] (Second heat exchanger 40) The second heat exchanger 40 exchanges heat between the air present around the second heat exchanger 40 and the refrigerant flowing inside the second heat exchanger 40. In the refrigeration cycle apparatus 100 shown in FIG. 1, the second heat exchanger 40 is an evaporator. The second heat exchanger 40, which is an evaporator, evaporates the refrigerant decompressed by the decompression device 30. The second heat exchanger 40 evaporates the refrigerant flowing inside the second heat exchanger 40, and cools the air present around the second heat exchanger 40 by the heat of evaporation generated at that time.

[0020] (Storage tank section 50) The storage tank 50 allows the refrigerant flowing therethrough to pass therethrough or stores the refrigerant flowing therethrough. The storage tank 50 can temporarily store the refrigerant flowing through the refrigerant circuit 70. The storage tank 50 is provided between the pressure reducing device 30 and the refrigerant intake port 10a of the compressor 10. The storage tank 50 is provided on the low-pressure side of the refrigeration cycle.

[0021] The storage tank unit 50 is provided on the low-pressure side of the refrigeration cycle between the decompression device 30 and the compressor 10 in the direction of refrigerant flow in the refrigerant circuit 70. In the refrigeration cycle apparatus 100 shown in Fig. 1, the storage tank unit 50 is provided between the second heat exchanger 40 and the suction port 10a of the compressor 10. That is, the storage tank unit 50 is provided between the second heat exchanger 40 and the compressor 10 in the direction of refrigerant flow in the refrigerant circuit 70.

[0022] The storage tank unit 50 may be provided on the low-pressure side of the refrigeration cycle between the decompression device 30 and the suction port 10a of the compressor 10 in the direction of refrigerant flow in the refrigerant circuit 70. Therefore, as in the refrigeration cycle apparatus 100 shown in Fig. 2, the storage tank unit 50 may be provided between the decompression device 30 and the second heat exchanger 40. That is, the storage tank unit 50 may be provided between the decompression device 30 and the second heat exchanger 40 in the direction of refrigerant flow in the refrigerant circuit 70.

[0023] It is assumed that the storage tank unit 50 will be retrofitted to a refrigeration cycle device that does not have a storage tank unit 50 during retrofitting. Retrofitting refers to, for example, replacing the refrigerant sealed in the refrigeration cycle device with another refrigerant and using the existing device. However, the storage tank unit 50 is not limited to a configuration in which it is retrofitted. The storage tank unit 50 may be provided during the manufacture of the refrigeration cycle device 100, in anticipation of a change in the refrigerant to be used in the future. Alternatively, the storage tank unit 50 may be provided in advance before retrofitting, in anticipation of a change in the refrigerant to be used in the future.

[0024] The storage tank unit 50 has pipes arranged in parallel, and one of the parallel pipes has a buffer tank 51 that stores the refrigerant, a first gate valve 52 located upstream of the buffer tank 51, and a second gate valve 53 located downstream of the buffer tank 51. The parallel pipes are a first pipe 78 and a second pipe 79 that form a parallel circuit through which the refrigerant flows between an upstream pipe 76 and a downstream pipe 77, which will be described later.

[0025] The storage tank unit 50 has an upstream pipe 76 and a downstream pipe 77 connected to the refrigerant pipe 75. The upstream pipe 76 is a pipe located upstream of a buffer tank 51 (described later) in the direction of refrigerant flow, and is connected to the refrigerant pipe 75 that constitutes the refrigerant circuit 70. The upstream pipe 76 is also a pipe located upstream of a first pipe 78 and a second pipe 79 (described later) in the direction of refrigerant flow.

[0026] The downstream piping 77 is a piping located downstream of the buffer tank 51 in the refrigerant flow direction, and is connected to a refrigerant piping 75 that constitutes the refrigerant circuit 70. The downstream piping 77 is also a piping located downstream of a first piping 78 and a second piping 79, which will be described later, in the refrigerant flow direction.

[0027] The storage tank 50 also has a first pipe 78 and a second pipe 79 that form a parallel refrigerant circuit between the upstream pipe 76 and the downstream pipe 77. In the storage tank 50, the first pipe 78 and the second pipe 79 form a parallel refrigerant circuit, and the upstream pipe 76, the first pipe 78 and the second pipe 79, and the downstream pipe 77 form a series refrigerant circuit. The upstream pipe 76, the downstream pipe 77, and the first pipe 78 may be pipes that form part of the main refrigerant circuit 70, and the second pipe 79 may be pipes that form a refrigerant circuit that is provided in parallel with the main refrigerant circuit 70.

[0028] As described above, the storage tank unit 50 has the upstream pipe 76, the downstream pipe 77, the first pipe 78, and the second pipe 79. The upstream pipe 76, the downstream pipe 77, the first pipe 78, and the second pipe 79 are connected to the refrigerant pipe 75 and constitute a part of the refrigerant circuit 70. That is, the upstream pipe 76, the downstream pipe 77, the first pipe 78, and the second pipe 79, together with the refrigerant pipe 75, constitute the refrigerant circuit 70.

[0029] The upstream piping 76, the downstream piping 77, and the first piping 78 may be formed separately from the refrigerant piping 75, or the upstream piping 76, the downstream piping 77, and the first piping 78 may be formed integrally with the refrigerant piping 75. That is, the upstream piping 76, the downstream piping 77, and the first piping 78 may use a portion of the refrigerant piping 75 that connects the second heat exchanger 40 and the compressor 10. Alternatively, the upstream piping 76, the downstream piping 77, and the first piping 78 may use a portion of the refrigerant piping 75 that connects the decompression device 30 and the second heat exchanger 40.

[0030] The storage tank unit 50 has a first gate valve 52, a buffer tank 51, and a second gate valve 53. The first gate valve 52, the buffer tank 51, and the second gate valve 53 are provided in a second pipe 79 of the storage tank unit 50. The first gate valve 52, the buffer tank 51, and the second gate valve 53 are arranged on a refrigerant flow path formed by the second pipe 79. In the flow direction of the refrigerant flowing through the second pipe 79, the first gate valve 52, the buffer tank 51, and the second gate valve 53 are arranged in this order.

[0031] The first pipe 78 is not provided with any device that affects the flow of the refrigerant, and is provided to directly connect the upstream pipe 76 and the downstream pipe 77. In the refrigeration cycle apparatus 100 shown in Fig. 1, the refrigerant flows from the second heat exchanger 40 to the compressor 10 through the first pipe 78 while the compressor 10 is operating. In the refrigeration cycle apparatus 100 shown in Fig. 2, the refrigerant flows from the pressure reducing device 30 to the second heat exchanger 40 through the first pipe 78 while the compressor 10 is operating.

[0032] The first gate valve 52 is a device that opens and closes the flow path, and adjusts the flow rate of the refrigerant flowing through the second pipe 79 in the refrigerant circuit 70. The first gate valve 52 is, for example, a two-way valve. The first gate valve 52 is an electronically controlled on-off valve that can adjust the opening degree of a valve such as a solenoid valve. The opening and closing of the first gate valve 52 is controlled by a control device 80, and the opening degree of the first gate valve 52 is adjusted by the control device 80.

[0033] The first gate valve 52 is provided in the second pipe 79. The first gate valve 52 is provided so as to be located upstream of the buffer tank 51 in the flow direction of the refrigerant that flows while the compressor 10 is operating. When the first gate valve 52 is open, it allows the refrigerant to flow into the buffer tank 51, and when the valve is closed, it prevents the refrigerant from flowing into the buffer tank 51.

[0034] In the case of the refrigeration cycle apparatus 100 shown in Fig. 1, when the first gate valve 52 is open, the refrigerant passes through the first gate valve 52 and flows into the second piping 79, and the refrigerant flowing out from the second heat exchanger 40 flows into the buffer tank 51. In the case of the refrigeration cycle apparatus 100 shown in Fig. 2, when the first gate valve 52 is open, the refrigerant passes through the first gate valve 52 and flows into the second piping 79, and the refrigerant flowing out from the pressure reducing device 30 flows into the buffer tank 51.

[0035] When the first gate valve 52 is closed, the second piping 79 is blocked by the first gate valve 52, and the refrigerant does not flow through the second piping 79, and the refrigerant does not flow from the second heat exchanger 40 or the pressure reducing device 30 into the buffer tank 51. In the refrigeration cycle apparatus 100 shown in FIG. 1, when the first gate valve 52 is closed, the refrigerant flowing out from the second heat exchanger 40 passes through the first piping 78 and is sucked into the compressor 10. In the refrigeration cycle apparatus 100 shown in FIG. 2, when the first gate valve 52 is closed, the refrigerant flowing out from the pressure reducing device 30 passes through the first piping 78 and flows into the second heat exchanger 40.

[0036] The buffer tank 51 is provided in the second pipe 79 between the first gate valve 52 and the second gate valve 53. That is, in the flow direction of the refrigerant flowing through the second pipe 79, the buffer tank 51 is provided so as to be located downstream of the first gate valve 52 and upstream of the second gate valve 53.

[0037] The buffer tank 51 is a container that stores a refrigerant. The buffer tank 51 can store the refrigerant up to a predetermined capacity. When the pressure inside the refrigeration cycle device 100 increases excessively, the refrigerant is released into the buffer tank 51 by controlling the opening and closing of the first gate valve 52 and the second gate valve 53 of the storage tank unit 50, thereby suppressing the increase in pressure inside the device. Furthermore, when the refrigeration cycle device 100 is stopped, the refrigeration cycle device 100 releases the refrigerant into the buffer tank 51 by controlling the opening and closing of the first gate valve 52 and the second gate valve 53 of the storage tank unit 50, thereby suppressing the increase in pressure inside the device when the device is stopped.

[0038] The second gate valve 53 is a device that opens and closes the flow path, and adjusts the flow rate of the refrigerant flowing through the second pipe 79 in the refrigerant circuit 70. The second gate valve 53 is, for example, a two-way valve. The second gate valve 53 is an electronically controlled on-off valve that can adjust the opening degree of a valve such as a solenoid valve. The opening and closing of the second gate valve 53 is controlled by the control device 80, and the opening degree of the second gate valve 53 is adjusted by the control device 80.

[0039] The second gate valve 53 is provided in the second pipe 79. The second gate valve 53 is provided so as to be located downstream of the buffer tank 51 in the flow direction of the refrigerant that flows while the compressor 10 is operating. The second gate valve 53 prevents the refrigerant from flowing back into the buffer tank 51 by closing the valve.

[0040] 1, when the second gate valve 53 is open, the refrigerant passes through the second gate valve 53 and flows through the second piping 79, and the refrigerant flowing out of the buffer tank 51 is sucked into the compressor 10. In the refrigeration cycle apparatus 100 shown in FIG. 2, when the second gate valve 53 is open, the refrigerant passes through the second gate valve 53 and flows through the second piping 79, and the refrigerant flowing out of the buffer tank 51 flows into the second heat exchanger 40.

[0041] When the second gate valve 53 is closed, the second gate valve 53 blocks the flow of refrigerant through the second piping 79, and refrigerant does not flow from the buffer tank 51 to the compressor 10. In the case of the refrigeration cycle apparatus 100 shown in FIG. 1, when the second gate valve 53 is closed, the refrigerant flowing out of the second heat exchanger 40 passes through the first piping 78 and is sucked into the compressor 10. In the case of the refrigeration cycle apparatus 100 shown in FIG. 2, when the second gate valve 53 is closed, the refrigerant flowing out of the pressure reducing device 30 passes through the first piping 78 and flows into the second heat exchanger 40.

[0042] (Refrigerant piping 75) In the refrigeration cycle apparatus 100, each device or each apparatus constituting the refrigeration cycle apparatus 100 is connected by refrigerant piping 75 to form a refrigerant circuit 70. The refrigerant piping 75 connects each device constituting the refrigeration cycle apparatus 100. Specifically, the refrigerant piping 75 connects the compressor 10, the first heat exchanger 20, the decompression device 30, the second heat exchanger 40, and the storage tank unit 50. A refrigerant flows inside the refrigerant piping 75.

[0043] In the refrigeration cycle apparatus 100, a compressor 10, a first heat exchanger 20, a pressure reducing device 30, a second heat exchanger 40, and a storage tank 50 are connected by refrigerant piping 75 to form a refrigerant circuit 70. The refrigerant circuit 70 is a closed circuit and forms a flow path through which the refrigerant flows. When the refrigeration cycle apparatus 100 is in operation, the refrigerant flows in circulation through the refrigerant circuit 70.

[0044] (Control device 80) The control device 80 controls each device provided in the refrigerant circuit 70. The control device 80 controls the operation of the entire refrigeration cycle device 100 based on various information received from each device of the refrigeration cycle device 100. For example, the control device 80 controls the operating frequency of the compressor 10, the valve opening of the pressure reducing device 30, the opening of the first gate valve 52, and the opening of the second gate valve 53, etc., based on information such as the start or stop of operation of the refrigeration cycle device 100. Note that starting the operation of the refrigeration cycle device 100 means circulating the refrigerant in the refrigerant circuit 70, and stopping the operation of the refrigeration cycle device 100 means stopping the circulation of the refrigerant in the refrigerant circuit 70. Even when the operation of the refrigeration cycle device 100 is stopped, the control device 80 is operating and can perform its functions.

[0045] Fig. 3 is a functional block diagram showing an example of the configuration of the control device 80 shown in Fig. 1. As shown in Fig. 3, the control device 80 includes an operating state determination unit 81, a storage unit 82, a timer unit 83, and an input unit 84. The control device 80 also includes a compressor control unit 85, a pressure reducing device control unit 86, and a valve control unit 87.

[0046] The operating state determination unit 81 controls the operation of the refrigeration cycle apparatus 100 based on the operating information of the refrigeration cycle apparatus 100 supplied from the compressor 10, the pressure reducing device 30, the first gate valve 52, and the second gate valve 53, and on control information previously determined in the memory unit 82. The operating information and control information of the refrigeration cycle apparatus 100 include, for example, the operating frequency of the compressor 10, the valve opening of the pressure reducing device 30, the opening of the first gate valve 52, and the opening of the second gate valve 53.

[0047] The operating information of the refrigeration cycle apparatus 100 may be supplied by communication from the compressor 10, the pressure reducing device 30, the first gate valve 52, and the second gate valve 53, or may utilize the current state of each device set in the control device 80. That is, the control device 80 may utilize, as the operating information of the refrigeration cycle apparatus 100, the operating frequency of the compressor 10, the valve opening of the pressure reducing device 30, the opening of the first gate valve 52, and the opening of the second gate valve 53, etc., currently set in the control device 80.

[0048] The operation of the refrigeration cycle device 100 is controlled by the control device 80 by adjusting the operating frequency of the compressor 10, the valve opening of the pressure reducing device 30, the opening of the first gate valve 52, the opening of the second gate valve 53, etc.

[0049] The storage unit 82 stores in advance programs, data, etc. necessary as control information used by the control device 80. The storage unit 82 stores information, etc. necessary when the control device 80 controls the devices that make up the refrigeration cycle apparatus 100. The storage unit 82 may also store various setting information input to the input unit 84.

[0050] The timing unit 83 is, for example, a timer or a real-time clock, and is used to acquire the current time and measure a set time. The timing unit 83 calculates the compressor stop time. For example, when the compressor 10 stops, the compressor stop time is the accumulated time from when the compressor 10 stopped to the present. When the operating state determination unit 81 determines that the compressor 10 has stopped, the timing unit 83 starts measuring the compressor stop time. The timing unit 83 is not limited to measuring only the compressor stop time, and may also measure, for example, the compressor operating time, and is capable of measuring all times related to the control of the refrigeration cycle apparatus 100.

[0051] The input unit 84 is an information input device used by the user when inputting information to the control device 80. The user can set the timer of the timing unit 83 via the input unit 84. The user can also start or stop the operation of the refrigeration cycle apparatus 100 via the input unit 84.

[0052] The compressor control unit 85 controls the operating frequency of the compressor 10 to control the rotation speed of the compressor 10 based on information from the operating state determination unit 81. The pressure reducing device control unit 86 controls the aperture of the pressure reducing device 30 based on information from the operating state determination unit 81. The valve control unit 87 controls the aperture of the first gate valve 52 and the aperture of the second gate valve 53 based on information from the operating state determination unit 81. In the functional block diagram of FIG. 3 , the operating state determination unit 81, the compressor control unit 85, the pressure reducing device control unit 86, and the valve control unit 87 are shown as having different configurations, but the operating state determination unit 81, the compressor control unit 85, the pressure reducing device control unit 86, and the valve control unit 87 may be integrated.

[0053] Fig. 4 is a hardware configuration diagram showing an example of the configuration of the control device 80 shown in Fig. 3. Here, an example of the hardware of the control device 80 shown in Fig. 3 will be described. When the various functions of the control device 80 are executed by hardware, the control device 80 shown in Fig. 3 is configured by a processing circuit 80a as shown in Fig. 4. The functions of the operating state determination unit 81, memory unit 82, timer unit 83, input unit 84, compressor control unit 85, pressure reducing device control unit 86, and valve control unit 87 shown in Fig. 3 are realized by the processing circuit 80a.

[0054] When each function is executed by hardware, the processing circuit 80a corresponds to, for example, a single circuit, a composite circuit, a programmed processor, a parallel programmed processor, an ASIC (Application Specific Integrated Circuit), an FPGA (Field-Programmable Gate Array), or a combination thereof. The functions of each of the operating state determination unit 81, the memory unit 82, the timer unit 83, the input unit 84, the compressor control unit 85, the pressure reducing device control unit 86, and the valve control unit 87 may be realized by individual processing circuits 80a, or the functions of these units may be realized by a single processing circuit 80a.

[0055] Fig. 5 is a hardware configuration diagram showing another example of the configuration of the control device 80 shown in Fig. 3. Here, another example of the hardware of the control device 80 shown in Fig. 3 will be described. When the various functions of the control device 80 are executed by software, the control device 80 has a processor 80b and a memory 80c, as shown in Fig. 5. The functions of the operating state determination unit 81, the storage unit 82, the timer unit 83, the input unit 84, the compressor control unit 85, the pressure reducing device control unit 86, and the valve control unit 87 are realized by the processor 80b and the memory 80c.

[0056] When each function is executed by software, the functions of the operating state determination unit 81, the memory unit 82, the timer unit 83, the input unit 84, the compressor control unit 85, the pressure reducing device control unit 86, and the valve control unit 87 are realized by software or firmware. Alternatively, when each function is executed by software, the functions of the operating state determination unit 81, the memory unit 82, the timer unit 83, the input unit 84, the compressor control unit 85, the pressure reducing device control unit 86, and the valve control unit 87 are realized by a combination of software and firmware. The software and firmware are written as programs and stored in the memory 80c. The processor 80b realizes the functions of each unit by reading and executing the programs stored in the memory 80c.

[0057] The memory 80c may be, for example, a non-volatile semiconductor memory such as a ROM (Read Only Memory), a flash memory, an EPROM (Erasable and Programmable ROM), or an EEPROM (Electrically Erasable and Programmable ROM). Alternatively, a volatile semiconductor memory such as a RAM (Random Access Memory) may be used as the memory 80c. Furthermore, the memory 80c may be a removable recording medium such as a magnetic disk, a flexible disk, an optical disk, a CD (Compact Disc), an MD (Mini Disc), or a DVD (Digital Versatile Disc).

[0058] The refrigeration cycle apparatus 100 may have a flow path switching device (not shown) in addition to the above configuration. The flow path switching device is, for example, a four-way valve, which switches the flow direction of the refrigerant. When the refrigeration cycle apparatus 100 has a four-way valve as the flow path switching device, the four-way valve may be connected as follows. The four-way valve is connected to a pipe connected to the discharge port 10b of the compressor 10, a pipe connected to the suction port 10a of the compressor 10, a pipe connected to the first heat exchanger 20, and a pipe connected to the second heat exchanger 40.

[0059] The flow path switching by the flow path switching device is performed by the control device 80. When the refrigeration cycle apparatus 100 is an air conditioner, the control device 80 switches between cooling operation and heating operation of the air conditioner by switching the flow path in the flow path switching device. When the refrigeration cycle apparatus 100 has a flow path switching device, the first heat exchanger 20 may function as an evaporator by switching the flow path by the flow path switching device. Also, when the refrigeration cycle apparatus 100 has a flow path switching device, the second heat exchanger 40 may function as a condenser by switching the flow path by the flow path switching device.

[0060] In addition, the refrigeration cycle device 100 may have a first blower (not shown) that supplies air to the first heat exchanger 20, and may have a second blower (not shown) that supplies air to the second heat exchanger 40.

[0061] [Operation of the refrigeration cycle device 100] Next, the operation of the refrigeration cycle apparatus 100 will be described with reference to Fig. 1. The refrigerant drawn into the compressor 10 is compressed by the compressor 10 and discharged in a high-temperature, high-pressure gas state. The high-temperature, high-pressure gas state refrigerant discharged from the compressor 10 passes through the refrigerant pipe 75 and flows into the first heat exchanger 20, which acts as a condenser.

[0062] The refrigerant that has flowed into the first heat exchanger 20 exchanges heat with the air present around the first heat exchanger 20. In the first heat exchanger 20, the refrigerant condenses and liquefies by dissipating heat to the air present around the first heat exchanger 20. At that time, the air present around the first heat exchanger 20 is warmed.

[0063] The liquid refrigerant that has flowed out of the first heat exchanger 20 flows through the refrigerant pipe 75 and flows into the pressure reducing device 30. The liquid refrigerant that has flowed into the pressure reducing device 30 is decompressed and expanded to become low-temperature, low-pressure, two-phase gas-liquid refrigerant. The two-phase gas-liquid refrigerant that has flowed out of the pressure reducing device 30 flows into the second heat exchanger 40, which functions as an evaporator.

[0064] The refrigerant that flows into the second heat exchanger 40 exchanges heat with the air present around the second heat exchanger 40, evaporating and gasifying. At this time, the air present around the second heat exchanger 40 is cooled by heat exchange with the refrigerant. The evaporated refrigerant in a low-temperature, low-pressure gas state then flows out of the second heat exchanger 40, passes through the storage tank 50, and is sucked into the compressor 10. The refrigerant sucked into the compressor 10 is compressed again by the compressor 10 into a high-temperature, high-pressure gas refrigerant, and is discharged.

[0065] In the case of the refrigeration cycle apparatus 100 shown in FIG. 2, the refrigerant in a gas-liquid two-phase state that flows out of the pressure reducing device 30 passes through the storage tank 50 and flows into the second heat exchanger 40, which acts as an evaporator. The refrigerant that flows into the second heat exchanger 40 exchanges heat with the air present around the second heat exchanger 40, evaporating and gasifying. At that time, the air present around the second heat exchanger 40 is cooled by the heat exchange with the refrigerant. The evaporated refrigerant in a low-temperature, low-pressure gas state then flows out of the second heat exchanger 40 and is drawn into the compressor 10. The refrigerant drawn into the compressor 10 is compressed again by the compressor 10 into a high-temperature, high-pressure gas refrigerant and is discharged.

[0066] Fig. 6 is a diagram showing the relationship between pressure [MPa] and elapsed time [s] in the refrigeration cycle apparatus 100 according to the first embodiment. Fig. 7 is a flow diagram showing an example of control of the refrigeration cycle apparatus 100 according to the first embodiment. Fig. 6 also shows an example of the pressure in the low-pressure side pipe. The low-pressure side pipe is a pipe that constitutes the refrigerant circuit 70 from the pressure reducing device 30 to the compressor 10 in the direction of refrigerant flow, and is a pipe that constitutes the refrigerant circuit 70 between the pressure reducing device 30 and the suction port 10a of the compressor 10.

[0067] The vertical axis in Fig. 6 represents pressure [MPa], and the horizontal axis represents elapsed time [s]. The design pressure P1 shown in Fig. 6 is the upper limit of the design pressure of the refrigeration cycle apparatus 100 and is stored in the memory unit 82. Next, the flow of refrigerant in the storage tank unit 50 and the control by the control device 80 will be described with reference to Figs. 6 and 7. Note that, before the control shown in Fig. 6, the refrigeration cycle apparatus 100 may perform a pump-down operation to recover the refrigerant.

[0068] In the pump-down operation, the refrigerant is recovered, for example, in the first heat exchanger 20. Regarding the concern that the design pressure may be exceeded when the refrigeration cycle apparatus 100 is stopped due to refrigerant that was not transferred to the refrigerant storage area during the pump-down operation, the refrigeration cycle apparatus 100 prevents the pressure inside the apparatus from exceeding the design pressure of the apparatus while the apparatus is stopped by using the control shown in FIG. 6. When performing the pump-down operation, it is common to provide a receiver (liquid reservoir) between the condenser and the expansion valve. Although not required, a receiver may be provided between the first heat exchanger 20 and the pressure reducing device 30. The refrigeration cycle apparatus 100 may or may not perform a pump-down operation to recover the refrigerant before the control shown in FIG. 6. The refrigeration cycle apparatus 100 can achieve its effect even if the pump-down operation to recover the refrigerant is not performed before the control shown in FIG. 6.

[0069] When the refrigeration cycle apparatus 100 is in operation, the control device 80 maintains the first gate valve 52 and the second gate valve 53 in a fully closed state, thereby blocking the refrigerant circuit 70 of the second piping 79 (step SP1). Therefore, when the refrigeration cycle apparatus 100 is in operation, the refrigerant does not flow through the refrigerant circuit 70 of the second piping 79, but flows through the refrigerant circuit 70 of the first piping 78. In FIG. 6, the period from time T0 to time T1 corresponds to the operation of the refrigeration cycle apparatus 100. Time T1 is the point in time when the refrigeration cycle apparatus 100 is stopped, as will be described later.

[0070] 1, the refrigerant that has flowed out of the second heat exchanger 40 flows through the first piping 78 of the storage tank 50 and is sucked into the compressor 10. In the refrigeration cycle apparatus 100 shown in FIG. 2, the refrigerant that has flowed out of the decompression device 30 flows through the first piping 78 of the storage tank 50 and flows into the second heat exchanger 40.

[0071] 6, the refrigeration cycle apparatus 100 is stopped (step SP2). When the control device 80 receives a command to stop the operation of the refrigeration cycle apparatus 100, it stops the operation of the compressor 10. Alternatively, the control device 80 stops the operation of the refrigeration cycle apparatus 100 by comparing the detection data of a suction pressure sensor 60 (see FIG. 9) or a suction temperature sensor 61 (see FIG. 13), which will be described later, with a threshold value stored in the memory unit 82.

[0072] The command to stop operation of the refrigeration cycle device 100 may be issued by user operation, or instead of the control device 80 receiving a command to stop operation, the control device 80 may determine to stop operation by receiving information from various sensors described below.

[0073] When the control device 80 receives a command to stop the operation of the refrigeration cycle apparatus 100, it determines whether or not a predetermined set time S1 has elapsed since the operation of the refrigeration cycle apparatus 100 was stopped (step SP3). This set time S1 is stored in the memory unit 82, and the timer unit 83 measures the set time S1, and the operating state determination unit 81 determines whether or not the set time S1 has elapsed.

[0074] When the control device 80 receives a command to stop the operation of the refrigeration cycle device 100 and the refrigeration cycle device 100 is stopped, the control device 80 opens the first gate valve 52 and the second gate valve 53 after a preset set time S1 has elapsed since the operation of the refrigeration cycle device 100 was stopped (step SP4). The control device 80 adjusts the opening degrees of the first gate valve 52 and the second gate valve 53 to a predetermined amount.

[0075] For example, when the control device 80 receives a command to stop operation of the refrigeration cycle apparatus 100, it fully opens the first gate valve 52 and the second gate valve 53. Time T2 shown in Fig. 6 is the time point at which the control device 80 opens the first gate valve 52 and the second gate valve 53. Note that the set time S1 may be a time close to zero, and when the control device 80 receives a command to stop operation of the refrigeration cycle apparatus 100, the control device 80 may immediately open the first gate valve 52 and the second gate valve 53.

[0076] When the refrigeration cycle apparatus 100 is stopped, with the compressor 10 driven and the first gate valve 52 and the second gate valve 53 maintained in a fully closed state, the control device 80 opens the first gate valve 52 and the second gate valve 53. In the refrigeration cycle apparatus 100, when the first gate valve 52 and the second gate valve 53 provided in the second piping 79 are opened, the refrigerant flows through the second piping 79. The refrigerant that passes through the first gate valve 52 flows into the buffer tank 51 and is stored therein. In a refrigeration cycle apparatus that does not have a storage tank 50, the pressure in the low-pressure side of the apparatus when stopped may exceed the design pressure of the apparatus. The refrigeration cycle apparatus 100 can suppress a pressure increase in the low-pressure piping by releasing the refrigerant in the low-pressure piping into the buffer tank 51.

[0077] Fig. 8 is a conceptual diagram showing the relationship between the first pipe 78 and the second pipe 79 of the refrigeration cycle apparatus 100 according to Embodiment 1. Note that Fig. 8 is for explaining the relationship between the first pipe 78 and the second pipe 79, and does not illustrate the first gate valve 52 and the second gate valve 53.

[0078] In the refrigeration cycle apparatus 100, since the pressure on the buffer tank 51 side is low, it is assumed that the refrigerant will move into the buffer tank 51 even when the compressor 10 is stopped. Note that in the refrigeration cycle apparatus 100, the first pipe 78 and the second pipe 79 may have one or more of the following configurations in order to move the refrigerant into the buffer tank 51.

[0079] In a first configuration, in the refrigeration cycle apparatus 100, the diameter of the second pipe 79 located upstream of the buffer tank 51 is made larger than the diameter of the first pipe 78 of the main refrigerant circuit. Here, the second pipe 79 located upstream of the buffer tank 51 is referred to as the upstream second pipe 79a. The diameter D2 of the upstream second pipe 79a is formed to be larger than the diameter D1 of the first pipe 78 (diameter D2>diameter D1).

[0080] As a second configuration, in the refrigeration cycle apparatus 100, the position height in the gravity direction of the second pipe 79 connected to the buffer tank 51 is set lower than the position height in the gravity direction of the first pipe 78 of the main refrigerant circuit. The refrigeration cycle apparatus 100 is formed so that the position of the upstream second pipe 79a connected to the buffer tank 51 is lower than the position of the first pipe 78 of the main refrigerant circuit. Because the refrigerant is taken into the buffer tank 51 in the form of gas refrigerant, it is desirable to connect the upstream second pipe 79a to the bottom of the container of the buffer tank 51.

[0081] When the refrigeration cycle apparatus 100 is operated, the refrigerant in the buffer tank 51 needs to be returned to the main refrigerant circuit 70. The main refrigerant circuit 70 is a refrigerant circuit 70 formed in a ring shape, passing through the compressor 10, the first heat exchanger 20, the pressure reducing device 30, the second heat exchanger 40, and the storage tank 50. In other words, the main refrigerant circuit 70 is a circuit used when performing a refrigeration cycle, and is a refrigerant circuit 70 formed in a ring shape using a refrigerant pipe 75 from the outlet of the storage tank 50 to the inlet of the storage tank 50 and a first pipe 78 of the storage tank 50.

[0082] Since the refrigerant in the buffer tank 51 needs to be returned to the main refrigerant circuit 70 after operation starts, the control device 80 closes the first gate valve 52 after operation of the refrigeration cycle device 100 starts, and moves the refrigerant in the buffer tank 51 to the main refrigerant circuit 70 while keeping the second gate valve 53 open.

[0083] Specifically, when the control device 80 receives a command to start the operation of the refrigeration cycle apparatus 100, the control device 80 starts the operation of the compressor 10, and starts the operation of the refrigeration cycle apparatus 100 (step SP5). Time T3 shown in Fig. 6 is the time point when the control device 80 starts the operation of the refrigeration cycle apparatus 100.

[0084] The command to start operation of the refrigeration cycle apparatus 100 may be issued by a user operation, or instead of receiving a command to start operation, the control device 80 may determine to start operation by receiving information from various sensors described below. The control device 80 may start operation of the refrigeration cycle apparatus 100 by comparing detection data from a suction pressure sensor 60 (see FIG. 9) or a suction temperature sensor 61 (see FIG. 13) described below with a threshold value stored in the memory unit 82.

[0085] When the control device 80 receives a command to start operation of the refrigeration cycle apparatus 100, it determines whether or not a predetermined set time S2 has elapsed since the start of operation of the refrigeration cycle apparatus 100 (step SP6). This set time S2 is stored in the memory unit 82, and the timer unit 83 measures the set time S2, and the operating state determination unit 81 determines whether or not the set time S2 has elapsed.

[0086] The control device 80 receives a command to start operation of the refrigeration cycle apparatus 100, and after a predetermined set time S2 has elapsed since the start of operation of the refrigeration cycle apparatus 100, closes the first gate valve 52 and adjusts the opening degree of the first gate valve 52 to a predetermined amount (step SP7). For example, when the control device 80 receives a command to start operation of the refrigeration cycle apparatus 100, it fully closes the first gate valve 52. When starting operation of the refrigeration cycle apparatus 100, the control device 80 fully closes the first gate valve 52 after a predetermined set time S2 has elapsed since the start of operation of the refrigeration cycle apparatus 100.

[0087] 6 is the time point at which the control device 80 closes the first gate valve 52. By setting a set time S2, the refrigeration cycle device 100 desirably keeps the first gate valve 52 open until refrigerant flows into the circuit on the buffer tank 51 side and a flow of refrigerant returning to the main circuit is established. If the set time S2 is zero, it is assumed that the operation of the compressor 10 will not cause refrigerant to enter the circuit on the buffer tank 51 side, and therefore there is a possibility that refrigerant will flow into the circuit on the buffer tank 51 side and a flow of refrigerant returning to the main circuit will not be established.

[0088] When the operation of the refrigeration cycle apparatus 100 is started after the refrigeration cycle apparatus 100 has been stopped, the control device 80 closes the first gate valve 52. Thereafter, the control device 80 closes the second gate valve 53 after the pressure in the buffer tank 51 has dropped. The control device 80 determines that the pressure in the buffer tank 51 has dropped by keeping the first gate valve 52 closed and the second gate valve 53 open for a predetermined time.

[0089] The control device 80 determines whether a predetermined set time S3 has elapsed since the first gate valve 52 was closed (step SP8). After the predetermined set time S3 has elapsed since the first gate valve 52 was closed (if step SP8 is YES), the control device 80 closes the second gate valve 53 (step SP9). Time T5 shown in Figure 6 is the time when the control device 80 closes the second gate valve 53.

[0090] A set time S3 from when the first gate valve 52 is closed to when the second gate valve 53 is closed may be set based on the volume of the buffer tank 51. This set time S3 is stored in the memory unit 82, and the set time S3 is measured by the timing unit 83, and the operating state determination unit 81 determines whether or not the set time S3 has elapsed. By closing the second gate valve 53, the refrigeration cycle apparatus 100 can prevent the refrigerant from flowing back into the buffer tank 51 from the side where the compressor 10 is located.

[0091] In the refrigeration cycle apparatus 100, the diameter of the second pipe 79 located downstream of the buffer tank 51 may be smaller than the diameter of the first pipe 78 to prevent backflow of the refrigerant. Here, as shown in Fig. 8, the second pipe 79 located downstream of the buffer tank 51 is referred to as the downstream second pipe 79b. The diameter D3 of the downstream second pipe 79b is formed to be smaller than the diameter D1 of the first pipe 78 (diameter D1>diameter D3).

[0092] [Actions and Effects of the Refrigeration Cycle Device 100] The refrigeration cycle apparatus 100 includes a storage tank 50 that is disposed between the pressure reducing device 30 and the intake port 10a of the compressor 10 and that allows a refrigerant flowing therethrough to pass therethrough or stores the refrigerant flowing therethrough. The storage tank 50 has parallel pipes, one of which includes a buffer tank 51 that stores the refrigerant, a first gate valve 52 located upstream of the buffer tank 51, and a second gate valve 53 located downstream of the buffer tank 51. When the refrigeration cycle apparatus 100 is stopped while the compressor 10 is operating and the first gate valve 52 and the second gate valve 53 are maintained fully closed, the control device 80 opens the first gate valve 52 and the second gate valve 53. The refrigeration cycle apparatus 100 can release pressure in the low-pressure side pipe to the buffer tank 51 of the storage tank 50 when the apparatus is stopped, under the control of the control device 80, even when a refrigerant with a high operating pressure is used after retrofitting. Therefore, the refrigeration cycle apparatus 100 can prevent the pressure inside the apparatus from exceeding the design pressure of the apparatus while the operation of the apparatus is stopped.

[0093] The refrigeration cycle apparatus 100 includes a storage tank 50 disposed between the pressure reducing device 30 and the suction port 10a of the compressor 10. The storage tank 50 allows the refrigerant flowing therethrough to pass therethrough or stores the refrigerant. The storage tank 50 has a first pipe 78 and a second pipe 79 that form a parallel refrigerant circuit. The first pipe 78 connects an upstream pipe 76 and a downstream pipe 77. The second pipe 79 is provided with a first gate valve 52, a buffer tank 51, and a second gate valve 53. The refrigeration cycle apparatus 100 can release pressure in the low-pressure pipe to the buffer tank 51 of the storage tank 50 during shutdown, even when using a refrigerant with a high operating pressure after retrofitting, by controlling the valves described above by the control device 80. Therefore, the refrigeration cycle apparatus 100 can prevent the pressure inside the apparatus from exceeding the design pressure during shutdown.

[0094] Furthermore, when the operation of the refrigeration cycle apparatus 100 is stopped, the control device 80 opens the first gate valve 52 and the second gate valve 53 after a preset set time S1 has elapsed since the operation of the refrigeration cycle apparatus 100 was stopped. By setting the set time S1 in relation to the rising pressure inside the apparatus, the refrigeration cycle apparatus 100 can reduce the number of times the first gate valve 52 and the second gate valve 53 are controlled.

[0095] Furthermore, when starting operation of the refrigeration cycle apparatus 100, the control device 80 fully closes the first gate valve 52 after a preset set time S2 has elapsed since the start of operation of the refrigeration cycle apparatus 100. By providing the set time S2, the refrigeration cycle apparatus 100 can form a flow of refrigerant that flows into the circuit on the buffer tank 51 side and returns to the main circuit. The refrigeration cycle apparatus 100 can reduce the number of times it controls the first gate valve 52 by setting the set time S2 in relation to the decreasing pressure inside the apparatus.

[0096] Furthermore, when the refrigeration cycle apparatus 100 is started from a stopped state, the control device 80 closes the first gate valve 52, and closes the second gate valve 53 after a preset set time S3 has elapsed since the first gate valve 52 was closed. The refrigeration cycle apparatus 100 can reduce the number of times it controls the second gate valve 53 by setting the set time S3 in relation to the decreasing pressure inside the apparatus.

[0097] The control device 80 controls the opening degree of the first gate valve 52 and the second gate valve 53. As a method for controlling the opening and closing of the valves of the storage tank section 50 after the device is stopped, the refrigeration cycle device 100 opens and closes the first gate valve 52 and the second gate valve 53 of the storage tank section 50 in conjunction with operation commands and stop commands of the device. The refrigeration cycle device 100 controls the opening and closing of the first gate valve 52 and the second gate valve 53 of the storage tank section 50 using the control of existing devices, so there is no need to significantly change the function of the existing devices. Such a refrigeration cycle device 100 and its control method can be implemented with minor software changes by reusing existing controls, and costs can be reduced compared to replacing the refrigeration cycle device 100.

[0098] Even if the pressure of the newly charged refrigerant is higher than the design pressure of the device when using the old refrigerant, the refrigeration cycle device 100 can control the pressure so as not to exceed the design pressure of the existing device by making a minor structural change by adding the storage tank unit 50 and by changing the software of the control device 80. Therefore, the refrigeration cycle device 100 can use a refrigerant with physical properties that have a higher pressure than the refrigerant currently in use, and if a refrigerant with a lower GWP is desired, this can be achieved by retrofitting a previously used refrigeration cycle device.

[0099] Furthermore, the refrigeration cycle apparatus 100 has the first pipe 78 and the second pipe 79 with one or more of the following configurations. In the first configuration, the diameter of the second pipe 79 located upstream of the buffer tank 51 is made larger than the diameter of the first pipe 78. In the second configuration, the position of the second pipe 79 connected to the buffer tank 51 is formed to be lower than the position of the first pipe 78. By having one or more of the above configurations, the refrigeration cycle apparatus 100 can easily transfer the refrigerant from inside the pipes to inside the buffer tank 51.

[0100] In the refrigeration cycle apparatus 100, the diameter D3 of the second pipe 79 located downstream of the buffer tank 51 is smaller than the diameter D1 of the first pipe 78. With the above-described configuration, the refrigeration cycle apparatus 100 can prevent the refrigerant from flowing back from the compressor 10 side to the inside of the buffer tank 51.

[0101] Embodiment 2 Fig. 9 is a refrigerant circuit diagram of a refrigeration cycle apparatus 100 according to embodiment 2. Fig. 10 is a functional block diagram showing an example of the configuration of the control device 80 shown in Fig. 9. Components having the same functions and actions as those of the refrigeration cycle apparatus 100 according to embodiment 1 are given the same reference numerals, and descriptions thereof will be omitted. The following description will focus on differences between embodiment 2 and embodiment 1, and configurations not described in embodiment 2 are the same as those in embodiment 1.

[0102] The refrigeration cycle apparatus 100 according to the second embodiment includes a suction pressure sensor 60 in the refrigerant circuit 70. The suction pressure sensor 60 detects the pressure of the refrigerant sucked into the compressor 10. The suction pressure sensor 60 is provided between the suction port 10a of the compressor 10 and the storage tank unit 50.

[0103] The suction pressure sensor 60 detects the pressure of the refrigerant, for example, by measuring the piping pressure of the refrigerant piping 75 connected to the suction port 10a of the compressor 10. The suction pressure sensor 60 detects the pressure of the refrigerant suctioned into the compressor 10, which is the low-pressure side pressure, and supplies the detected pressure data to an operating state determination unit 81 of the control device 80.

[0104] The operating state determination unit 81 controls the operation of the refrigeration cycle device 100 based on the operating information of the refrigeration cycle device 100 described above, the pressure data detected by the suction pressure sensor 60, and the control information stored in the memory unit 82.

[0105] [Operation of the refrigeration cycle device 100] Fig. 11 is a diagram showing the relationship between pressure [MPa] and elapsed time [s] in the refrigeration cycle apparatus 100 according to embodiment 2. Fig. 12 is a flow diagram showing an example of control of the refrigeration cycle apparatus 100 according to embodiment 2. The operation of the refrigeration cycle apparatus 100 according to embodiment 2 is the same as that of the refrigeration cycle apparatus 100 according to embodiment 1, except for the conditions under which the first gate valve 52 and the second gate valve 53 are opened.

[0106] The refrigeration cycle apparatus 100 according to the second embodiment differs from the refrigeration cycle apparatus 100 according to the first embodiment in the process of step SP3. As shown in Fig. 7, when the control device 80 according to the first embodiment receives a command to stop the operation of the refrigeration cycle apparatus 100, it determines whether or not a predetermined set time S1 has elapsed since the operation of the refrigeration cycle apparatus 100 was stopped (step SP3).

[0107] Then, the control device 80 of embodiment 1 receives a command to stop operation of the refrigeration cycle device 100, and after a predetermined set time S1 has elapsed since operation of the refrigeration cycle device 100 was stopped, opens the first gate valve 52 and the second gate valve 53 (step SP4).

[0108] As shown in Figures 11 and 12, when the control device 80 of embodiment 2 receives a command to stop operation of the refrigeration cycle device 100, it determines whether the detected pressure, which is the pressure detected by the suction pressure sensor 60, is greater than or equal to the set pressure P2 (step SP3).

[0109] The set pressure P2 is a pressure stored in advance in the memory unit 82 as the upper limit of the design pressure of the refrigeration cycle apparatus 100 when it is used. The set pressure P2 is a threshold value for opening the first gate valve 52 and the second gate valve 53. As shown in FIG. 11, the set pressure P2 is a value that has a margin with respect to the design pressure P1 of the refrigeration cycle apparatus 100 (set pressure P2<design pressure P1). Note that the set pressure P2 may be the same value as the design pressure P1 of the refrigeration cycle apparatus 100 (set pressure P2=design pressure P1).

[0110] When the control device 80 of the second embodiment determines that the detected pressure detected by the suction pressure sensor 60 is equal to or higher than the set pressure P2, it opens the first gate valve 52 and the second gate valve 53 (step SP4). Note that even when the refrigeration cycle device 100 of the second embodiment is not operating, the control device 80 and the suction pressure sensor 60 are in operation and can perform their respective functions.

[0111] When the refrigeration cycle apparatus 100 is stopped, the control device 80 determines whether the detected pressure, which is the pressure detected by the suction pressure sensor 60, is equal to or greater than a set pressure P2 that is pre-stored as the upper limit of the design pressure of the apparatus when the refrigeration cycle apparatus 100 is in use. If the detected pressure is equal to or greater than the set pressure P2, the control device 80 opens the first gate valve 52 and the second gate valve 53. The suction pressure sensor 60 can also be used to close the first gate valve 52 and the second gate valve 53.

[0112] For example, in the refrigeration cycle apparatus 100, a delay in closing the second gate valve 53 may cause a backflow of refrigerant, and an early closing of the second gate valve 53 may result in a shortage of refrigerant flowing through the main circuit. Therefore, the control device 80 closes the second gate valve 53 when it determines, based on the pressure on the suction side of the compressor 10 detected by the suction pressure sensor 60, that a sufficient amount of refrigerant has been discharged from the buffer tank 51. Note that, because the state of the refrigerant may not be determined from the pressure on the suction side of the compressor 10, a suction pressure sensor 60 may be provided in the second pipe 79 or the buffer tank 51, and the state of the refrigerant may be determined from the pressure value to determine the timing of closing the first gate valve 52 or the second gate valve 53.

[0113] The refrigeration cycle apparatus 100 according to the second embodiment may control the first gate valve 52 and the second gate valve 53 in conjunction with the measurement value of an existing low-pressure side suction pressure sensor 60, for example, a pressure sensor attached to the suction side of the compressor 10. The refrigeration cycle apparatus 100 according to the second embodiment can be adapted with minor modifications by providing a storage tank section 50 to an existing refrigeration cycle apparatus and reusing the control of the existing low-pressure side suction pressure sensor 60 and control device 80.

[0114] [Actions and Effects of the Refrigeration Cycle Device 100] When the refrigeration cycle apparatus 100 is out of operation, the control device 80 determines whether the detected pressure, which is the pressure detected by the suction pressure sensor 60, is equal to or greater than a set pressure P2 that is stored in advance as the upper limit of the design pressure of the apparatus when the refrigeration cycle apparatus 100 is in use. The control device 80 opens the first gate valve 52 and the second gate valve 53 when the detected pressure is equal to or greater than the set pressure P2.

[0115] When the refrigeration cycle apparatus 100 according to the second embodiment is stopped, the first gate valve 52 and the second gate valve 53 are opened only when the pressure in the refrigerant pipe 75 rises excessively, by control based on the measurement value of the suction pressure sensor 60. Therefore, the refrigeration cycle apparatus 100 according to the second embodiment can appropriately time the control of the first gate valve 52 and the second gate valve 53, and can reduce the number of times the first gate valve 52 and the second gate valve 53 are controlled, compared to when the control is not based on the measurement value of the suction pressure sensor 60.

[0116] Furthermore, since the refrigeration cycle apparatus 100 according to embodiment 2 has a configuration similar to that of the refrigeration cycle apparatus 100 according to embodiment 1, it can achieve the same effects as the refrigeration cycle apparatus 100 according to embodiment 1.

[0117] The refrigeration cycle apparatus 100 according to the second embodiment may use the detection data of the suction pressure sensor 60 when stopping the operation of the refrigeration cycle apparatus 100 in step SP2 and starting the operation of the refrigeration cycle apparatus 100 in step SP5. For example, the control device 80 according to the second embodiment may stop the operation of the refrigeration cycle apparatus 100 when it determines that the detected pressure detected by the suction pressure sensor 60 is equal to or higher than a first threshold value SH1. The control device 80 according to the second embodiment may start the operation of the refrigeration cycle apparatus 100 when it determines that the detected pressure detected by the suction pressure sensor 60 is equal to or lower than a second threshold value SH2.

[0118] Embodiment 3 Fig. 13 is a refrigerant circuit diagram of a refrigeration cycle apparatus 100 according to embodiment 3. Fig. 14 is a functional block diagram showing an example of the configuration of the control device 80 shown in Fig. 13. Components having the same functions and actions as those of the refrigeration cycle apparatus 100 according to embodiment 1 or embodiment 2 are given the same reference numerals, and their description will be omitted. The following description will focus on differences between embodiment 3 and embodiment 1 or embodiment 2, and configurations not described in embodiment 3 are the same as those in embodiment 1 or embodiment 2.

[0119] The refrigeration cycle apparatus 100 according to the third embodiment includes a suction temperature sensor 61 in the refrigerant circuit 70. The suction temperature sensor 61 detects the temperature of the refrigerant suctioned into the compressor 10. The suction temperature sensor 61 is provided between the suction port 10a of the compressor 10 and the storage tank unit 50.

[0120] The suction temperature sensor 61 detects the temperature of the refrigerant, for example, by measuring the piping temperature of the refrigerant piping 75 connected to the suction port 10a of the compressor 10. The suction temperature sensor 61 detects the temperature of the refrigerant suctioned into the compressor 10, which is the temperature on the low-pressure side, and supplies the detected temperature data to the operating state determination unit 81 of the control device 80.

[0121] The operating state determination unit 81 controls the operation of the refrigeration cycle device 100 based on the operating information of the refrigeration cycle device 100 described above, the temperature data detected by the intake temperature sensor 61, and the control information stored in the memory unit 82.

[0122] [Operation of the refrigeration cycle device 100] 15 is a flow diagram showing an example of control of the refrigeration cycle apparatus 100 according to embodiment 3. The operation of the refrigeration cycle apparatus 100 according to embodiment 3 is similar to that of the refrigeration cycle apparatus 100 according to embodiment 1 except for the conditions under which the first gate valve 52 and the second gate valve 53 are opened.

[0123] The refrigeration cycle apparatus 100 according to the third embodiment differs from the refrigeration cycle apparatus 100 according to the first embodiment in the process of step SP3. As shown in Fig. 15, when the control device 80 according to the third embodiment receives a command to stop the operation of the refrigeration cycle apparatus 100, the control device 80 determines whether the detected temperature, which is the temperature detected by the intake temperature sensor 61, is equal to or higher than the set temperature TE (step SP3).

[0124] The set temperature TE is a temperature that is stored in advance in the memory unit 82 as an upper limit value when using the refrigeration cycle apparatus 100. The set temperature TE is a threshold value for opening the first gate valve 52 and the second gate valve 53. The set temperature TE is a value that has a margin with respect to the design temperature of the refrigeration cycle apparatus 100 (set temperature TE<design temperature). Note that the set temperature TE may be the same value as the design temperature of the refrigeration cycle apparatus 100 (set temperature TE=design temperature).

[0125] When the control device 80 of the third embodiment determines that the detected temperature detected by the suction temperature sensor 61 is equal to or higher than the set temperature TE, it opens the first gate valve 52 and the second gate valve 53 (step SP4). Note that even when the refrigeration cycle device 100 of the third embodiment is not operating, the control device 80 and the suction temperature sensor 61 are in operation and can perform their respective functions.

[0126] When the refrigeration cycle apparatus 100 is stopped, the control device 80 determines whether the detected temperature, which is the temperature detected by the intake temperature sensor 61, is equal to or higher than a set temperature TE that is pre-stored as an upper limit value for use of the refrigeration cycle apparatus 100. Then, the control device 80 opens the first gate valve 52 and the second gate valve 53 when the detected temperature is equal to or higher than the set temperature TE.

[0127] The refrigeration cycle apparatus 100 according to the third embodiment may use the detection data of the suction temperature sensor 61 when stopping the operation of the refrigeration cycle apparatus 100 in step SP2 and starting the operation of the refrigeration cycle apparatus 100 in step SP5. For example, the control device 80 according to the third embodiment may stop the operation of the refrigeration cycle apparatus 100 when it determines that the detected temperature detected by the suction temperature sensor 61 is equal to or higher than a first threshold value ST1. Furthermore, the control device 80 according to the third embodiment may start the operation of the refrigeration cycle apparatus 100 when it determines that the detected temperature detected by the suction temperature sensor 61 is equal to or lower than a second threshold value ST2.

[0128] The refrigeration cycle apparatus 100 according to the third embodiment may control the first gate valve 52 and the second gate valve 53 in conjunction with the measurement value of an existing low-pressure side suction temperature sensor 61, for example, a temperature sensor attached to the suction side of the compressor 10. The refrigeration cycle apparatus 100 according to the third embodiment can be adapted with minor modifications by providing a storage tank section 50 to an existing refrigeration cycle apparatus and utilizing the existing low-pressure side suction temperature sensor 61 and the control of the control device 80.

[0129] The refrigeration cycle apparatus 100 according to the third embodiment may perform control by converting the temperature detected by the suction temperature sensor 61 into pressure. In this case, the control device 80 of the refrigeration cycle apparatus 100 performs control according to, for example, a control flow as shown in Fig. 12. That is, the refrigeration cycle apparatus 100 uses the suction temperature sensor 61 instead of the suction pressure sensor 60 in the control shown in Fig. 12.

[0130] The suction temperature sensor 61 can also be used when closing the first gate valve 52 and the second gate valve 53. As described in the second embodiment, the control device 80 of the refrigeration cycle device 100 may determine the state of the refrigerant from the detection value of the suction temperature sensor 61 and determine the timing to close the first gate valve 52 or the second gate valve 53.

[0131] [Actions and Effects of the Refrigeration Cycle Device 100] When the refrigeration cycle apparatus 100 is stopped, the control device 80 determines whether the detected temperature, which is the temperature detected by the intake temperature sensor 61, is equal to or higher than a set temperature TE that is pre-stored as an upper limit value for use of the refrigeration cycle apparatus 100. The control device 80 opens the first gate valve 52 and the second gate valve 53 when the detected temperature is equal to or higher than the set temperature TE.

[0132] When the refrigeration cycle apparatus 100 according to the third embodiment is stopped, the first gate valve 52 and the second gate valve 53 are opened only when the temperature in the refrigerant pipe 75 rises excessively, by control based on the measurement value of the suction temperature sensor 61. Therefore, the refrigeration cycle apparatus 100 according to the third embodiment can appropriately time the control of the first gate valve 52 and the second gate valve 53 compared to when the control is not based on the measurement value of the suction temperature sensor 61, and can reduce the number of times the first gate valve 52 and the second gate valve 53 are controlled.

[0133] Furthermore, since the refrigeration cycle apparatus 100 according to embodiment 3 has a configuration similar to that of the refrigeration cycle apparatus 100 according to embodiment 1, it can achieve the same effects as the refrigeration cycle apparatus 100 according to embodiment 1.

[0134] Embodiment 4 Fig. 16 is a refrigerant circuit diagram of a refrigeration cycle apparatus 100 according to embodiment 4. Fig. 17 is a functional block diagram showing an example of the configuration of the control device 80 shown in Fig. 16. Components having the same functions and actions as those of the refrigeration cycle apparatus 100 according to embodiments 1 to 3 are given the same reference numerals, and descriptions thereof will be omitted. The following description will focus on differences between embodiment 4 and embodiments 1 to 3, and configurations not described in embodiment 4 are the same as those in embodiments 1 to 3.

[0135] The storage tank unit 50 of the fourth embodiment has pipes arranged in parallel, and one of the parallel pipes has a buffer tank 51 that stores a refrigerant, a first gate valve 52 located upstream of the buffer tank 51, and a second gate valve 53 that is a check valve located downstream of the buffer tank 51. The refrigeration cycle apparatus 100 of the fourth embodiment has a second gate valve 53a in the second pipe 79 of the storage tank unit 50. The second gate valve 53a of the fourth embodiment is provided at the position of the second gate valve 53 of the first embodiment. That is, in the flow direction of the refrigerant flowing through the storage tank unit 50, the second gate valve 53a is provided at a position downstream of the buffer tank 51.

[0136] The second gate valve 53a is a check valve. In the storage tank 50 of the refrigeration cycle apparatus 100, the second gate valve 53a allows the refrigerant to flow from the buffer tank 51 to the suction port 10a side of the compressor 10, but prevents the refrigerant from flowing from the suction port 10a side of the compressor 10 to the buffer tank 51.

[0137] 17, in storage tank section 50, the opening degree of only first gate valve 52 is controlled by control device 80. That is, the opening degree of second gate valve 53a is not controlled by control device 80.

[0138] Fig. 18 is a flow diagram showing an example of control of the refrigeration cycle apparatus 100 according to Embodiment 4. Next, the flow of the refrigerant in the storage tank unit 50 and the control by the control device 80 will be described with reference to Fig. 18.

[0139] When the refrigeration cycle apparatus 100 is in operation, the control device 80 maintains the first gate valve 52 in a fully closed state to block the refrigerant circuit 70 of the second piping 79 (step SP1). Therefore, when the refrigeration cycle apparatus 100 is in operation, the refrigerant does not flow through the refrigerant circuit 70 of the second piping 79, but flows through the refrigerant circuit 70 of the first piping 78.

[0140] The user stops the refrigeration cycle apparatus 100 (step SP2). When the control device 80 receives a command to stop the operation of the refrigeration cycle apparatus 100, the control device 80 stops the operation of the compressor 10. Alternatively, the control device 80 stops the operation of the refrigeration cycle apparatus 100 by comparing the detection data of the suction pressure sensor 60 or the suction temperature sensor 61 with a threshold value stored in the memory unit 82.

[0141] When the control device 80 receives the command to stop the operation of the refrigeration cycle apparatus 100, it determines whether or not a predetermined set time S1 has elapsed since the operation of the refrigeration cycle apparatus 100 was stopped (step SP3).

[0142] The control device 80 receives a command to stop operation of the refrigeration cycle apparatus 100, and opens the first gate valve 52 after a predetermined set time S1 has elapsed since operation of the refrigeration cycle apparatus 100 was stopped (step SP4). The control device 80 adjusts the opening degree of the first gate valve 52 to a predetermined amount. For example, when the control device 80 receives a command to stop operation of the refrigeration cycle apparatus 100, it fully opens the first gate valve 52. When operation of the refrigeration cycle apparatus 100 is stopped, the control device 80 opens the first gate valve 52 after a predetermined set time S1 has elapsed since operation of the refrigeration cycle apparatus 100 was stopped.

[0143] When the compressor 10 is driven and the first gate valve 52 is maintained in a fully closed state, the control device 80 opens the first gate valve 52 when the refrigeration cycle apparatus 100 is stopped. When the first gate valve 52 provided in the second piping 79 opens, the refrigerant flows through the second piping 79. The refrigerant that has passed through the first gate valve 52 flows into the buffer tank 51 and is stored in the buffer tank 51. The refrigeration cycle apparatus 100 can suppress a pressure increase in the low-pressure side piping by releasing the refrigerant in the low-pressure side piping into the buffer tank 51.

[0144] Since the refrigerant in the buffer tank 51 needs to be returned to the main refrigerant circuit 70 after operation starts, the control device 80 closes the first gate valve 52 after operation of the refrigeration cycle device 100 starts, and moves the refrigerant in the buffer tank 51 to the main refrigerant circuit 70.

[0145] Specifically, when the control device 80 receives a command to start the operation of the refrigeration cycle apparatus 100, the control device 80 starts the operation of the compressor 10, and starts the operation of the refrigeration cycle apparatus 100 (step SP5). When the control device 80 receives the command to start the operation of the refrigeration cycle apparatus 100, the control device 80 determines whether a predetermined set time S2 has elapsed since the operation of the refrigeration cycle apparatus 100 started (step SP6).

[0146] The control device 80 receives a command to start operation of the refrigeration cycle apparatus 100, and after a predetermined set time S2 has elapsed since the start of operation of the refrigeration cycle apparatus 100, closes the first gate valve 52 and adjusts the opening degree of the first gate valve 52 to a predetermined amount (step SP7). For example, when the control device 80 receives a command to start operation of the refrigeration cycle apparatus 100, it fully closes the first gate valve 52. When starting operation of the refrigeration cycle apparatus 100, the control device 80 fully closes the first gate valve 52 after a predetermined set time S2 has elapsed since the start of operation of the refrigeration cycle apparatus 100.

[0147] When the refrigeration cycle apparatus 100 has the suction pressure sensor 60 of the second embodiment, the control device 80 may perform control as follows: When the refrigeration cycle apparatus 100 is stopped, the control device 80 determines whether the detected pressure, which is the pressure detected by the suction pressure sensor 60, is equal to or greater than a set pressure P2 that is stored in advance as the upper limit of the design pressure of the apparatus when the refrigeration cycle apparatus 100 is in use (step SP3). When the detected pressure is equal to or greater than the set pressure P2, the control device 80 opens the first gate valve 52.

[0148] Furthermore, when the refrigeration cycle apparatus 100 has the suction temperature sensor 61 of the third embodiment, the control device 80 may perform control as follows: When the refrigeration cycle apparatus 100 is stopped, the control device 80 determines whether the detected temperature, which is the temperature detected by the suction temperature sensor 61, is equal to or higher than a set temperature TE that is stored in advance as an upper limit value when the refrigeration cycle apparatus 100 is used (step SP3). The control device 80 opens the first gate valve 52 when the detected temperature is equal to or higher than the set temperature TE.

[0149] [Actions and Effects of the Refrigeration Cycle Device 100] The refrigeration cycle apparatus 100 includes a storage tank 50 disposed between the pressure reducing device 30 and the intake port 10a of the compressor 10. The storage tank 50 allows the refrigerant flowing therethrough to pass therethrough or stores the refrigerant. The storage tank 50 has parallel pipes, one of which includes a buffer tank 51 for storing the refrigerant, a first gate valve 52 located upstream of the buffer tank 51, and a second gate valve 53, which is a check valve located downstream of the buffer tank 51. The control device 80 opens the first gate valve 52 when the refrigeration cycle apparatus 100 is stopped while the compressor 10 is operating and the first gate valve 52 is maintained in a fully closed state. The control device 80 controls the refrigeration cycle apparatus 100 to release pressure in the low-pressure side pipe between the pressure reducing device 30 and the compressor 10 to the buffer tank 51 of the storage tank 50 when the apparatus is stopped, even when a refrigerant with a high operating pressure is used after retrofitting. Therefore, the refrigeration cycle apparatus 100 can prevent the pressure inside the apparatus from exceeding the design pressure of the apparatus while the operation of the apparatus is stopped.

[0150] The storage tank unit 50 of the refrigeration cycle apparatus 100 according to the fourth embodiment has a first pipe 78 and a second pipe 79 that form a parallel refrigerant circuit. The first pipe 78 is provided to connect an upstream pipe 76 and a downstream pipe 77, and the second pipe 79 is provided with a first gate valve 52, a buffer tank 51, and a second gate valve 53a, which is a check valve. The refrigeration cycle apparatus 100 can release the pressure in the low-pressure pipe between the pressure reducing device 30 and the compressor 10 to the buffer tank 51 of the storage tank unit 50 when the apparatus is shut down, even when a refrigerant with a high operating pressure is used after retrofitting, by controlling the valves described above by the control device 80. Therefore, the refrigeration cycle apparatus 100 can prevent the pressure inside the apparatus from exceeding the design pressure of the apparatus when the apparatus is shut down.

[0151] In the refrigeration cycle apparatus 100, the second gate valve 53a is a check valve, and therefore it is possible to prevent the refrigerant from flowing back from the side where the compressor 10 is located into the buffer tank 51. The refrigeration cycle apparatus 100 according to the fourth embodiment has the second gate valve 53a which is a check valve, and therefore it is not necessary to control the opening and closing of the second gate valve 53a located downstream of the buffer tank 51, and therefore the control of the refrigeration cycle apparatus 100 becomes easier.

[0152] Furthermore, even when a refrigerant with a high operating pressure is used after retrofitting, the refrigeration cycle apparatus 100 can release the pressure in the low-pressure piping to the buffer tank 51 of the storage tank unit 50 when the apparatus is stopped, using the first gate valve 52 and the buffer tank 51. Therefore, even when a refrigerant with a high operating pressure is used after retrofitting, the refrigeration cycle apparatus 100 can prevent the pressure inside the apparatus from exceeding the design pressure of the apparatus when the apparatus is stopped. When using a refrigerant with a low GWP, users do not need to replace the refrigeration cycle apparatus itself that they are currently using or replace equipment such as compressors, which allows them to reduce the cost of installing the refrigeration cycle apparatus and shorten the construction period.

[0153] Furthermore, when the refrigeration cycle apparatus 100 is stopped, the control device 80 opens the first gate valve 52 after a preset set time S1 has elapsed since the operation of the refrigeration cycle apparatus 100 has stopped. The refrigeration cycle apparatus 100 can reduce the number of times it controls the first gate valve 52 by setting the set time S1 in relation to the increasing pressure inside the apparatus.

[0154] Furthermore, when the refrigeration cycle apparatus 100 is stopped, the control device 80 determines whether the detected pressure, which is the pressure detected by the suction pressure sensor 60, is equal to or greater than a set pressure P2 that is pre-stored as the upper limit of the design pressure of the apparatus when the refrigeration cycle apparatus 100 is in use. The control device 80 opens the first gate valve 52 when the detected pressure is equal to or greater than the set pressure P2. Therefore, the refrigeration cycle apparatus 100 can appropriately time the control of the first gate valve 52 and reduce the number of times the first gate valve 52 is controlled, compared to when the control is not based on the measurement value of the suction pressure sensor 60.

[0155] When the refrigeration cycle apparatus 100 is stopped, the control device 80 determines whether the detected temperature, which is the temperature detected by the suction temperature sensor 61, is equal to or higher than the set temperature TE that is pre-stored as the upper limit value for use of the refrigeration cycle apparatus 100. The control device 80 opens the first gate valve 52 when the detected temperature is equal to or higher than the set temperature TE. Therefore, the refrigeration cycle apparatus 100 can appropriately time the control of the first gate valve 52 and reduce the number of times the first gate valve 52 is controlled, compared to when the control is not based on the measurement value of the suction temperature sensor 61.

[0156] When starting operation of the refrigeration cycle apparatus 100, the control device 80 fully closes the first gate valve 52 after a preset set time S2 has elapsed since the start of operation of the refrigeration cycle apparatus 100. The refrigeration cycle apparatus 100 can reduce the number of times it controls the first gate valve 52 by setting the set time S2 in relation to the decreasing pressure inside the apparatus.

[0157] The configurations shown in the above embodiments are examples of the contents of the present disclosure, and may be combined with other known technologies, and part of the configuration may be omitted or modified without departing from the scope of the present disclosure. In addition, the refrigeration cycle device 100 may be a combination of the first to fourth embodiments. [Explanation of symbols]

[0158] 10 compressor, 10a intake port, 10b discharge port, 20 first heat exchanger, 30 pressure reducing device, 40 second heat exchanger, 50 storage tank section, 51 buffer tank, 52 first gate valve, 53 second gate valve, 53a second gate valve, 60 intake pressure sensor, 61 intake temperature sensor, 70 refrigerant circuit, 75 refrigerant piping, 76 upstream side piping, 77 downstream side piping, 78 first piping, 79 second piping, 79a upstream side second piping, 79b downstream side second piping, 80 control device, 80a processing circuit, 80b processor, 80c memory, 81 operating state determination section, 82 memory section, 83 timing section, 84 input section, 85 compressor control section, 86 pressure reducing device control section, 87 valve control section, 100 refrigeration cycle device.

Claims

1. A refrigeration cycle device using a refrigeration cycle, a compressor that compresses a refrigerant; a first heat exchanger that condenses the refrigerant discharged from the compressor; a pressure reducing device that reduces the pressure of the refrigerant flowing out of the first heat exchanger; a second heat exchanger that evaporates the refrigerant decompressed by the decompression device; a storage tank portion provided between the pressure reducing device and a suction port of the compressor, the storage tank portion allowing the refrigerant flowing therethrough to pass therethrough or storing the refrigerant flowing therethrough; a refrigerant pipe that connects the compressor, the first heat exchanger, the decompression device, the second heat exchanger, and the storage tank to form a refrigerant circuit; a control device that controls each device provided in the refrigerant circuit; Equipped with The storage tank section is The refrigerant ... and The control device In a state where the compressor is driven and the first gate valve and the second gate valve are maintained in a fully closed state, when the refrigeration cycle device is stopped, the first gate valve and the second gate valve are opened, The storage tank section is an upstream pipe and a downstream pipe connected to the refrigerant pipe; The first gate valve is a valve that is provided to be located upstream of the buffer tank in the flow direction of the refrigerant that flows while the compressor is operating, and that allows the refrigerant to flow into the buffer tank when the valve is opened and prevents the refrigerant from flowing into the buffer tank when the valve is closed, The second gate valve is a valve that is provided downstream of the buffer tank in the flow direction of the refrigerant that flows while the compressor is operating, and that prevents the refrigerant from flowing back into the buffer tank by closing the valve; The parallel pipes are a first pipe and a second pipe that configure a parallel circuit through which the refrigerant flows between the upstream pipe and the downstream pipe, The first pipe is The upstream pipe and the downstream pipe are connected to each other. The second pipe has: the first gate valve, the buffer tank, and the second gate valve are provided, The first pipe and the second pipe, A refrigeration cycle device comprising one or more of the following configurations: a configuration in which the diameter of the second pipe located upstream of the buffer tank is larger than the diameter of the first pipe; and a configuration in which the position of the second pipe connected to the buffer tank is formed lower than the position of the first pipe.

2. The control device 2. The refrigeration cycle device according to claim 1, wherein when the operation of the refrigeration cycle device is stopped, the first gate valve and the second gate valve are opened after a predetermined set time has elapsed since the operation of the refrigeration cycle device was stopped.

3. a suction pressure sensor for detecting the pressure of the refrigerant drawn into the compressor; The control device A refrigeration cycle device as described in claim 1, wherein when the refrigeration cycle device is stopped, the first gate valve and the second gate valve are opened if the detected pressure detected by the suction pressure sensor is equal to or higher than a set pressure pre-stored as the upper limit value of the design pressure of the device when using the refrigeration cycle device.

4. The compressor further includes an intake temperature sensor that detects the temperature of the refrigerant being drawn into the compressor. The control device A refrigeration cycle device as described in claim 1, wherein when the refrigeration cycle device is stopped, the first gate valve and the second gate valve are opened if the detected temperature detected by the intake temperature sensor is higher than a set temperature pre-stored as an upper limit value when using the refrigeration cycle device.

5. The control device A refrigeration cycle device according to any one of claims 1 to 4, wherein when starting operation of the refrigeration cycle device, the first gate valve is fully closed after a predetermined set time has elapsed since the start of operation of the refrigeration cycle device.

6. The control device A refrigeration cycle device as described in any one of claims 1 to 4, wherein when operation of the refrigeration cycle device is started from a stopped state, the first gate valve is closed, and the second gate valve is closed after a predetermined set time has elapsed since the first gate valve was closed.

7. A refrigeration cycle device using a refrigeration cycle, a compressor that compresses a refrigerant; a first heat exchanger that condenses the refrigerant discharged from the compressor; a pressure reducing device that reduces the pressure of the refrigerant flowing out of the first heat exchanger; a second heat exchanger that evaporates the refrigerant decompressed by the decompression device; a storage tank portion provided between the pressure reducing device and a suction port of the compressor, the storage tank portion allowing the refrigerant flowing therethrough to pass therethrough or storing the refrigerant flowing therethrough; a refrigerant pipe that connects the compressor, the first heat exchanger, the decompression device, the second heat exchanger, and the storage tank to form a refrigerant circuit; a control device that controls each device provided in the refrigerant circuit; Equipped with The storage tank section is The refrigerant ... and The control device When the compressor is driven and the first gate valve is maintained in a fully closed state, the first gate valve is opened when the refrigeration cycle device is stopped. The storage tank section is an upstream pipe and a downstream pipe connected to the refrigerant pipe; The first gate valve is a valve that is provided to be located upstream of the buffer tank in the flow direction of the refrigerant that flows while the compressor is operating, and that allows the refrigerant to flow into the buffer tank when the valve is opened and prevents the refrigerant from flowing into the buffer tank when the valve is closed, The second gate valve is a valve that is provided downstream of the buffer tank in the flow direction of the refrigerant that flows while the compressor is operating, and that prevents the refrigerant from flowing back into the buffer tank; The parallel pipes are a first pipe and a second pipe that configure a parallel circuit through which the refrigerant flows between the upstream pipe and the downstream pipe, The first pipe is The upstream pipe and the downstream pipe are connected to each other. The second pipe has: the first gate valve, the buffer tank, and the second gate valve are provided, A refrigeration cycle device having one or more of the following configurations: a configuration in which the first pipe and the second pipe are connected together such that the diameter of the second pipe located upstream of the buffer tank is larger than the diameter of the first pipe; and a configuration in which the position of the second pipe connected to the buffer tank is lower than the position of the first pipe.

8. The parallel pipes of the storage tank section are the first pipe connected to the refrigerant pipe constituting the refrigerant circuit serving as a main circuit; the second pipe being parallel to the first pipe and having the buffer tank provided therein; The refrigeration cycle device according to any one of claims 1 to 4 and 7, comprising:

9. 8. The refrigeration cycle apparatus according to claim 1, wherein the diameter of the second pipe located downstream of the buffer tank is smaller than the diameter of the first pipe.

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