Refrigeration cycle equipment

Abstract

To reliably and accurately detect refrigerant leaks not only in stable operation but also in transient situations such as intermittent operation and defrosting. [Solution] The refrigeration cycle device (1) according to the embodiment includes an accumulator (24) and a compressor (21). The refrigeration cycle device (1) includes a temperature sensor (G) provided in the downstream flow path of the accumulator (24) for detecting temperature data of the refrigerant in the flow path, and a determination means (F2) for determining refrigerant leakage based on the temperature data.

Description

Technical Field

[0001] Embodiments of the present invention relate to a refrigeration cycle apparatus.

Background Art

[0002] In a refrigeration cycle in which refrigerant discharged from a compressor is passed through a condenser, a decompressor, and an evaporator and returned to the compressor, refrigerant may leak from a connection portion of a pipe through which the refrigerant passes. It is desirable to be able to reliably detect this refrigerant leakage.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] The problem to be solved by the present invention is to provide a refrigeration cycle apparatus that can reliably and accurately detect refrigerant leakage not only in a stable operating state but also in transient situations such as intermittent operation and defrosting operation.

Means for Solving the Problems

[0005] The refrigeration cycle apparatus according to an embodiment of the present invention includes an accumulator and a compressor. The refrigeration cycle apparatus includes a temperature sensor provided in a downstream flow path of the accumulator for detecting temperature data of the refrigerant in the flow path, and a determination means for determining refrigerant leakage based on the temperature data detected in a cooling operation step in which the equalizing valve is closed, the expansion valve is opened, and liquid refrigerant is accumulated in the accumulator.

[0006] In the refrigeration cycle apparatus according to an embodiment of the present invention, the temperature sensor is preferably provided in a flow path of a suction pipe for connecting the accumulator to the compressor.

[0007] In a refrigeration cycle device according to an embodiment of the present invention, it is preferable that the determination means determines refrigerant leakage by comparing the time at which a singularity appears in which the slope based on the time progression of the suction temperature of the suction pipe changes at the time of determination with the time at which a singularity appears in which the slope based on the time progression of the suction temperature of the suction pipe changes at the reference time.

[0008] In a refrigeration cycle device according to an embodiment of the present invention, it is preferable that the determination means calculates the saturated evaporation temperature based on the suction pressure of the compressor and estimates the time at which the singularity appears by comparing the suction temperature of the suction pipe with the saturated evaporation temperature.

[0009] In a refrigeration cycle device according to an embodiment of the present invention, it is preferable that the temperature sensor is further provided in the flow path of the oil return piping connected to the accumulator, and that the determination means determines the refrigerant leak based on the temperature data detected by each temperature sensor.

[0010] In a refrigeration cycle apparatus according to an embodiment of the present invention, the temperature sensor is preferably provided in the flow path of the refrigerant piping on the discharge side of the compressor.

[0011] In a refrigeration cycle device according to an embodiment of the present invention, it is preferable that the determination means determines refrigerant leakage by comparing the time at which a singularity appears in which the slope based on the time progression of the discharge temperature of the refrigerant piping changes at the time of determination with the time at which a singularity appears in which the slope based on the time progression of the discharge temperature of the refrigerant piping changes at the reference time.

[0012] In a refrigeration cycle device according to an embodiment of the present invention, it is preferable that the determination means determines refrigerant leakage based on a change in the rate of change of the discharge temperature of the refrigerant piping.

[0013] In a refrigeration cycle apparatus according to an embodiment of the present invention, it is preferable that the determination means determines the refrigerant leak based on the temperature data in the cooling operation process.

Advantages of the Invention

[0014] According to the present invention, refrigerant leakage can be reliably and accurately detected not only in a stable operating state but also in transient situations such as intermittent operation and defrosting operation.

Brief Description of the Drawings

[0015] [Figure 1] Schematic configuration diagram showing a refrigeration cycle apparatus according to an embodiment. [Figure 2] Diagram showing the states of valves in each process of the refrigeration cycle in a refrigeration cycle apparatus according to an embodiment in tabular form. [Figure 3] Diagram showing operations in a heating startup process and a heating operation process in a refrigeration cycle apparatus according to an embodiment. [Figure 4] Diagram showing operations in a heating stop process in a refrigeration cycle apparatus according to an embodiment. [Figure 5] Diagram showing operations in a cooling startup process in a refrigeration cycle apparatus according to an embodiment. [Figure 6] Schematic diagram showing changes in the liquid level of an accumulator in a refrigeration cycle apparatus according to an embodiment. [Figure 7] Diagram showing, as a graph, the behavior of the temperature of the refrigerant on the downstream side of an accumulator provided in a refrigeration cycle apparatus according to an embodiment. [Figure 8] Diagram showing the configuration of a control device provided in a refrigeration cycle apparatus according to an embodiment. [Figure 9] Schematic configuration diagram showing a modified example of an accumulator provided in a refrigeration cycle apparatus according to an embodiment.

Modes for Carrying Out the Invention

[0016] Hereinafter, embodiments of a refrigeration cycle apparatus will be described in detail with reference to the drawings.

[0017] (Embodiment) FIG. 1 is a schematic configuration diagram of a refrigeration cycle apparatus according to an embodiment.

[0018] FIG. 1 shows a hot gas type refrigeration cycle apparatus 1 according to an embodiment. The refrigeration cycle apparatus 1 is, for example, a so-called chiller. The refrigeration cycle apparatus 1 includes a first heat exchanger 11 as an air heat exchanger that performs heat exchange between a refrigerant circulating in the refrigeration cycle apparatus 1 and air, and a second heat exchanger 12 as a water heat exchanger that performs heat exchange between the refrigerant circulating in the refrigeration cycle apparatus 1 and water or brine (not shown) flowing through the utilization side. Note that the refrigeration cycle apparatus 1 may be an air conditioner, a water heater, or the like in addition to the chiller.

[0019] The first heat exchanger 11 performs heat exchange between the air supplied by an air-side blower 13 such as a fan installed in the vicinity and the refrigerant. Specifically, the first heat exchanger 11 functions as a condenser that dissipates the heat of the refrigerant to the air to condense the refrigerant during the cooling operation. Further, the first heat exchanger 11 functions as an evaporator that evaporates the refrigerant and cools the outdoor air by the heat of vaporization during the heating operation.

[0020] The second heat exchanger 12 functions as a condenser or an evaporator, and performs heat exchange between the refrigerant flowing in the refrigerant circuit and a heat medium such as water or brine flowing in the heat medium circuit by a flow water pump 14.

[0021] Further, the refrigeration cycle apparatus 1 includes a compressor 21, a four-way valve 22, an expansion valve 23, an accumulator 24, a liquid storage tank 25, and a liquid tank 26. Then, the compressor 21, the four-way valve 22, the first heat exchanger 11, the expansion valve 23, the second heat exchanger 12, and the accumulator 24 are connected in a ring shape in order by a refrigerant pipe, thereby forming the main circuit of the refrigerant circuit.

[0022] The compressor 21 draws in low-temperature, low-pressure refrigerant, compresses it into a high-temperature, high-pressure gaseous refrigerant, and discharges it. As the compressor 21, for example, an inverter compressor can be used, which allows control of the capacity, or the amount of refrigerant delivered per unit time, by arbitrarily changing the drive frequency. In addition, a low-pressure sensor (not shown) is provided on the suction side of the compressor 21 to detect the pressure of the refrigerant drawn into the compressor 21.

[0023] The four-way valve 22 switches the direction of refrigerant flow between cooling operation (including cooling startup) and heating operation (including heating startup) under control by the control device 40, which will be described later. Note that the four-way valve 22 is an example of a refrigerant flow path switching device. The refrigerant flow path switching device is not limited to the four-way valve 22 and may be a combination of other valves (for example, a two-way valve). The expansion valve 23 is, for example, a PMV (Pulse Motor Valve), and its opening degree is adjustable.

[0024] The accumulator 24 is located on the suction side, which is the low-pressure side of the compressor 21. The accumulator 24 stores excess refrigerant resulting from differences in operating conditions between cooling and heating operations, as well as excess refrigerant due to transient changes in operation. The liquid storage tank 25 is located on the refrigerant suction side of the compressor 21. The liquid tank 26 stores the liquid refrigerant for the refrigeration cycle.

[0025] Here, when comparing the amount of refrigerant required for the refrigerant circuit during cooling operation and heating operation, the second heat exchanger 12 is more efficient at condensing the refrigerant than the first heat exchanger 11. Therefore, the volume of the refrigerant side in the second heat exchanger 12 can be reduced. As a result, less refrigerant is required for the refrigerant circuit during heating operation than during cooling operation. In other words, during heating operation, there is a surplus of refrigerant required for the refrigerant circuit, so the excess liquid refrigerant flows into and is stored in the liquid tank 26. On the other hand, when switching from heating operation to cooling operation, there is a shortage of refrigerant required for the refrigerant circuit, so the liquid refrigerant stored in the liquid tank 26 flows into the refrigerant circuit.

[0026] Furthermore, the refrigeration cycle device 1 includes a first refrigerant pipe 281, a second refrigerant pipe 282, and a third refrigerant pipe 283. The first refrigerant pipe 281 connects the second heat exchanger 12 and the four-way valve 22. The second refrigerant pipe 282 connects the four-way valve 22 and the accumulator 24. The third refrigerant pipe 283 connects the compressor 21 and the four-way valve 22. A liquid-side pipe 5 is connected to one end of the second heat exchanger 12, and the first refrigerant pipe 281 is connected to the other end.

[0027] Furthermore, the refrigeration cycle device 1 includes a suction pipe 284 and connecting pipes 285 and 286. The suction pipe 284 guides gaseous refrigerant from the top of the accumulator 24 to the compressor 21. The connecting pipe 285 connects the liquid storage tank 25 to the compressor 21. The refrigeration cycle device 1 is also equipped with a pressure equalization valve 29 on the connecting pipe 286. The pressure equalization valve 29 is operated by control of the control device 40.

[0028] Furthermore, the refrigeration cycle device 1 is equipped with a temperature sensor E in the discharge flow path of the accumulator 24 to detect the temperature data of the refrigerant in the flow path. The temperature sensor E may be provided as a temperature sensor Es in the flow path of the suction pipe 284 that leads the refrigerant from the accumulator 24 to the compressor 21, or as a temperature sensor Ed in the flow path of the third refrigerant pipe 283 that leads from the compressor 21 to the four-way valve 22. The temperature sensor E is provided as at least one of the temperature sensors Es and Ed. The temperature sensor E detects the temperature of the gaseous refrigerant and transmits the digitized temperature data to the control device 40.

[0029] Next, we will explain the operation of the refrigeration cycle device 1.

[0030] Figure 2 is a table showing the state of valves 22, 29, and 23 in each step of the refrigeration cycle device 1.

[0031] The operation of the refrigeration cycle device 1 consists of a heating process and a cooling (defrosting) process. The heating process consists of (1) a heating start process, (2) a heating operation process, and (3) a heating stop process. The cooling process consists of (4) a cooling start process, (5) a cooling operation process, and (6) a cooling stop process. The hot gas type cooling (defrosting) operation proceeds in the following order: (2) heating operation process, (3) heating stop process, (4) cooling start process, (5) cooling operation process, (6) cooling stop process, (1) heating start process, and (2) heating operation process.

[0032] In (1) the heating startup process and (2) the heating operation process, the control device 40 controls the four-way valve 22 to the heating side (discharging high-temperature, high-pressure gaseous refrigerant to the second heat exchanger 12), the pressure equalization valve 29 is closed, and the expansion valve 23 is opened. In (1) the heating startup process and (2) the heating operation process, as shown by the solid arrows in Figure 3, the refrigerant is discharged from the compressor 21 as high-temperature, high-pressure gaseous refrigerant and flows to the second heat exchanger 12. This gaseous refrigerant is condensed in the second heat exchanger 12 and flows into the liquid side piping 5 as a liquid. Then, the liquid refrigerant flows from the liquid side piping 5 through the expansion valve 23 to the first heat exchanger 11. In this first heat exchanger 11, the liquid refrigerant evaporates and becomes gaseous as it exchanges heat with the outside air.

[0033] Furthermore, the gaseous refrigerant discharged from the first heat exchanger 11 flows into the gas-side piping 6. This low-temperature, low-pressure gaseous refrigerant then flows into the accumulator 24, where the refrigerant liquid is separated. The compressor 21 draws in only the gas from the accumulator 24, compresses it into a high-temperature, high-pressure gaseous state, and discharges it again from the compressor 21. In the heating operation process (2) after the heating startup process (1), the excess refrigerant is stored in the liquid tank 26, which has volume on the high-pressure side.

[0034] (3) During the heating stop process, the control device 40 controls the four-way valve 22 to the heating side, the pressure equalization valve 29 to open, and the expansion valve 23 to close. (3) During the heating stop process, as shown by the dashed arrow in Figure 4, the liquid refrigerant in the liquid tank 26 flows through the pressure equalization valve 29 to the accumulator 24 and the first heat exchanger 11, which are low pressure and low temperature, as the pressure equalization process is completed. The second heat exchanger 12 is relatively hot because hot water flows through it. The compressor 21 is also relatively hot because it has just started operating.

[0035] (4) In the cooling startup process, the control device 40 controls the four-way valve 22 to the cooling side (discharging high-temperature, high-pressure gaseous refrigerant to the first heat exchanger 11), the pressure equalization valve 29 is closed, and the expansion valve 23 is opened. (4) In the cooling startup process, as shown by the solid arrows in Figure 5, the refrigerant is discharged from the compressor 21 as a high-temperature, high-pressure gaseous substance and flows into the gas-side piping 6. Then, in the refrigeration cycle device 1, the gaseous refrigerant flows into the first heat exchanger 11. In this first heat exchanger 11, the gaseous refrigerant is condensed and liquefied by heat exchange with the outside air.

[0036] Furthermore, the liquid refrigerant discharged from the first heat exchanger 11 of the refrigeration cycle device 1 flows into the liquid-side piping 5 via the expansion valve 23. The liquid refrigerant then flows from the liquid-side piping 5 into the second heat exchanger 12. In this second heat exchanger 12, the liquid refrigerant is evaporated and turned into gas through heat exchange. This low-temperature, low-pressure gaseous refrigerant flows into the accumulator 24, and the liquid level in the accumulator 24 decreases as the liquid refrigerant is turned into gaseous, high-temperature gaseous refrigerant by the compressor 21, and is discharged again from the compressor 21.

[0037] (5) During the cooling operation process, the control device 40 controls the four-way valve 22 to the cooling side (discharging high-temperature, high-pressure gaseous refrigerant to the first heat exchanger 11), the pressure equalization valve 29 is closed, and the expansion valve 23 is opened. (5) During the cooling operation process, similar to the cooling startup process (4), the liquid level in the accumulator 24 drops further due to the gasification of the liquid refrigerant.

[0038] (6) During the cooling stop process, the control device 40 controls the four-way valve 22 to the cooling side, the pressure equalization valve 29 to open, and the expansion valve 23 to close.

[0039] Here, during the (3) heating stop process, liquid refrigerant flows into the accumulator 24. Then, from the (4) cooling start process to the (5) cooling operation process, gaseous refrigerant flows into the accumulator 24, and the liquid refrigerant accumulated in the accumulator 24 during the (3) heating stop process gradually turns into gas. The amount of liquid refrigerant accumulated in the accumulator 24 (i.e., the liquid level) differs between normal operation without refrigerant leakage and leakage operation with refrigerant leakage, as shown in Figure 6. Consequently, the time required for the liquid refrigerant in the accumulator 24 to turn into gas also differs.

[0040] Therefore, in (5) the cooling operation process, by detecting the temperature of the refrigerant downstream of the accumulator 24 (shown in Figure 7) with the temperature sensor E, the control device 40, described later, can estimate the amount of refrigerant in the accumulator 24, and thus can determine whether the refrigerant leakage is within the normal range or abnormal. For example, the temperature of the refrigerant (suction temperature) Ts that the compressor 21 draws in from the accumulator 24 is detected by the temperature sensor Es. In addition, since the behavior of the suction temperature Ts of the accumulator 24 is highly sensitive to the temperature of the refrigerant (discharge temperature) Td discharged from the compressor 21, the temperature of the discharge temperature Td of the compressor 21 can also be detected by the temperature sensor Ed to determine whether the refrigerant leakage is within the normal range or abnormal.

[0041] The control device 40 then compares the time at which a singularity appears in which the slope based on the time progression of the suction temperature Ts at the time of determination changes with the time at which a singularity appears in which the slope based on the time progression of the suction temperature Ts changes during a reference time (for example, during normal conditions). If the time difference Ds between these two is less than a threshold, the control device 40 determines that the refrigerant leakage is within the normal range. On the other hand, if the time difference Ds is greater than or equal to the threshold, the control device 40 determines that the refrigerant leakage is abnormal, that is, that there is a leak. In this case, it means that the amount of refrigerant in the accumulator 24 is decreasing.

[0042] Similarly, the control device 40 compares the time at which a singularity appears in which the slope based on the time progression of the discharge temperature Td changes at the time of determination with the time at which a singularity appears in which the slope based on the time progression of the discharge temperature Td changes under normal conditions. If the time difference Dd between these two is less than a threshold, the control device 40 determines that the refrigerant leakage is within the normal range. On the other hand, if the time difference Dd is greater than or equal to the threshold, the control device 40 determines that the refrigerant leakage is abnormal, that is, that there is a leakage. In this case, it means that the amount of refrigerant in the accumulator 24 is decreasing.

[0043] In this way, the refrigeration cycle device 1 determines refrigerant leakage during refrigeration cycle operation. The refrigeration cycle device 1 can determine refrigerant leakage during refrigeration cycle operation even when the refrigeration cycle is in a transient state, such as during the cooling operation process. In other words, the refrigeration cycle device 1 can determine refrigerant leakage even when it is in a transient cooling (defrosting) operation.

[0044] Next, the configuration of the control device 40 provided in the refrigeration cycle device 1 will be described.

[0045] Figure 8 shows the configuration of the control device 40 provided in the refrigeration cycle device 1.

[0046] Figure 8 shows the configuration of the control device 40 of the refrigeration cycle device 1. The control device 40 comprises a processing unit 41 and a storage unit 42. The control device 40 may also include an input unit for giving various instructions to the processing unit 41, a display unit for displaying images showing various information, etc.

[0047] The processing unit 41 is, for example, a circuit equipped with a CPU or a dedicated or general-purpose processor. The processor realizes various functions described later by executing various programs stored in the memory unit 42. The processing unit 41 may also be composed of hardware such as an FPGA (field programmable gate array) or an ASIC (application specific integrated circuit). Various functions described later can also be realized by this hardware. Furthermore, the processing unit 41 can realize various functions by combining software processing by the processor and programs with hardware processing.

[0048] The memory unit 42 is a storage medium that includes ROM (Read Only Memory), RAM (Random Access Memory), and external storage devices such as HDD (Hard Disk Drive) and optical disc drives. The memory unit 42 stores various information and data, as well as various programs executed by the processor provided in the processing unit 41.

[0049] The processing unit 41 implements the temperature acquisition means F1, the determination means F2, and the control means F3 by reading and executing a computer program stored in the memory unit 42 or directly incorporated into the processing unit 41. The following explanation will use the case where means F1 to F3 function in software by executing a computer program as an example, but all or part of the functions of means F1 to F3 may be implemented by circuits such as ASICs.

[0050] The temperature acquisition means F1 has the function of acquiring temperature data of the refrigerant in the flow path downstream of the accumulator 24 from the temperature sensor E. For example, the temperature acquisition means F1 can acquire the suction temperature Ts of the accumulator 24 from the temperature sensor Es, or the discharge temperature Td of the compressor 21 from the temperature sensor Ed.

[0051] The determination means F2 has the function of determining refrigerant leakage during refrigeration cycle operation based on temperature data acquired by the temperature acquisition means F1. The determination means F2 can also output the determination result as image data via a display unit (not shown).

[0052] For example, the determination means F2 compares the time (timing) at which a singularity appears in which the slope based on the time progression of the suction temperature Ts (shown in Figure 7) changes during the determination with the time (timing) at which a singularity appears in which the slope based on the time progression of the suction temperature Ts changes during normal conditions. If the time difference Ds (shown in Figure 7) between these two singularities is less than a threshold, the determination means F2 determines that the refrigerant leakage is within the normal range. On the other hand, if the time difference Ds is greater than or equal to the threshold, the determination means F2 determines that the refrigerant leakage is abnormal, that is, that there is a leakage. In this case, it means that the amount of refrigerant in the accumulator 24 is decreasing.

[0053] Similarly, the determination means F2 compares the time (timing) at which a singularity appears in which the slope based on the time progression of the discharge temperature Td (shown in Figure 7) changes during the determination with the time (timing) at which a singularity appears in which the slope based on the time progression of the discharge temperature Td changes during normal operation. If the time difference Dd (shown in Figure 7) between these two singularities is less than the threshold, the determination means F2 determines that the refrigerant leakage is within the normal range. On the other hand, if the time difference Dd is greater than or equal to the threshold, the determination means F2 determines that the refrigerant leakage is abnormal, that is, that there is a leakage. In this case, it means that the amount of refrigerant in the accumulator 24 is decreasing.

[0054] The determination means F2 can estimate the time at which a singularity appears by converting the saturated evaporation temperature based on the suction pressure of the compressor 21 and comparing the suction temperature Ts with the saturated evaporation temperature. The determination means F2 determines that a singularity has appeared if the suction temperature Ts is higher than the saturated evaporation temperature. This is because the refrigerant temperature during the phase change from liquid to gas is equal to the saturated evaporation temperature, and the temperature does not rise no matter how much heat is absorbed during the phase change, but on the other hand, after the phase change is completed and the refrigerant has gasified, the refrigerant temperature rises with the absorption of heat. In other words, if the suction temperature Ts is below the saturated evaporation temperature, it can be inferred that the refrigerant remains in liquid form, while if the suction temperature Ts is higher than the saturated evaporation temperature, it can be inferred that the liquid refrigerant has run out. The presence or absence of refrigerant leakage is determined by indirectly quantifying and comparing the amount of refrigerant from the time it takes for this phase change.

[0055] Furthermore, for example, the determination means F2 determines refrigerant leakage based on the rate of change of the discharge temperature Td. The determination means F2 determines that refrigerant leakage is within the normal range if the slope (temperature rise gradient) based on the time progression of the discharge temperature Td is below a threshold. On the other hand, the determination means F2 determines that refrigerant leakage is abnormal, that is, that there is leakage, if the slope based on the time progression of the discharge temperature Td is greater than the threshold. In this case, it means that the amount of refrigerant in the accumulator 24 is decreasing.

[0056] Here, the refrigeration cycle device 1 is equipped with at least one of the temperature sensors Es and Ed. For example, if the refrigeration cycle device 1 is equipped with either the temperature sensor Es or the temperature sensor Ed, the determination means F2 can make a determination based on the time progression of the suction temperature Ts or the discharge temperature Td, as described above. On the other hand, if the refrigeration cycle device 1 is equipped with both the temperature sensors Es and Ed, the determination means F2 may determine that there is a possibility of leakage if it determines that there is leakage based on either the time progression of the suction temperature Ts or the discharge temperature Td, while only determining that there is leakage if it determines that there is leakage based on the time progression of both the suction temperature Ts and Td.

[0057] The control means F3 has the function of controlling the operation of the refrigeration cycle device 1 and the indoor unit 3 in response to instructions for heating operation or cooling (defrosting) operation.

[0058] As described above, the determination means F2 of the refrigeration cycle device 1 determines refrigerant leakage during refrigeration cycle operation. This makes it possible to determine refrigerant leakage during refrigeration cycle operation even in transient states of the refrigeration cycle, such as during the cooling operation process. In other words, the refrigeration cycle device 1 can determine refrigerant leakage even when it is undergoing transient cooling (defrosting) operation. Furthermore, the refrigeration cycle device 1 can determine refrigerant leakage during refrigeration cycle operation in the same manner during the heating start process, cooling start process, etc.

[0059] (modified version) In the above-described embodiment, as shown in Figure 9(A), a configuration was described in which refrigerant oil used for lubricating the compressor 21 is guided to the compressor 21 from an oil return hole (not shown) provided in the suction pipe 284 within the accumulator 24. However, the configuration is not limited to this case. For example, as shown in Figure 9(B), an oil return pipe 287 may be provided at the bottom of the accumulator 24 to guide refrigerant oil used for lubricating the compressor 21 from the bottom of the accumulator 24 to the suction pipe 284. In this case, a temperature sensor G is provided in the flow path of the oil return pipe 287.

[0060] In the configuration shown in Figure 9(B), the temperature acquisition means F1 of the control device 40 acquires refrigerant oil temperature data from the temperature sensor G. The determination means F2 then determines refrigerant leakage based on the temperature data detected by the temperature sensors Es and G. For example, the determination means F2 compares the time at which a singularity appears in which the slope based on the time progression of the representative temperatures of the suction temperature Ts and refrigerant oil temperature changes at the time of determination with the time at which a singularity appears in which the slope based on the time progression of the representative temperature changes under normal conditions. If the time difference between these two is less than a threshold, the determination means F2 determines that the refrigerant leakage is within the normal range. On the other hand, if the time difference is greater than or equal to the threshold, the determination means F2 determines that the refrigerant leakage is abnormal, i.e., that there is a leak. In this case, it means that the amount of refrigerant in the accumulator 24 is decreasing. The representative temperature includes not only the simple average value based on both temperatures, but also the maximum value, minimum value, weighted average value, etc.

[0061] As a result, the configuration shown in Figure 9(B) provides the same effect as the configuration shown in Figure 9(A).

[0062] According to the embodiments described above, refrigerant leakage can be reliably and accurately detected not only in stable operation conditions but also in transient situations such as intermittent operation and defrosting operation.

[0063] While several embodiments have been described, these embodiments are presented as examples only and are not intended to limit the scope of the invention. These novel embodiments can be implemented in a variety of other forms, and various omissions, substitutions, modifications, combinations of embodiments, and combinations of embodiments with one or more modifications can be made without departing from the spirit of the invention. These embodiments and their variations are included in the scope and spirit of the invention, as well as in the claims and their equivalents. [Explanation of Symbols]

[0064] 1...Refrigeration cycle device, 11...First heat exchanger, 12...Second heat exchanger, 21...Compressor, 24...Accumulator, 41...Processing unit, E, Es, Ed, G...Temperature sensors, F1...Acquisition means, F2...Determination means, F3...Control means

Claims

1. A refrigeration cycle system comprising an accumulator and a compressor, A temperature sensor is provided in the downstream flow path of the accumulator and detects the temperature data of the refrigerant in the flow path, A determination means for determining refrigerant leakage based on the temperature data detected during a cooling operation process in which the pressure equalization valve is closed, the expansion valve is open, and liquid refrigerant is accumulated in the accumulator, A refrigeration cycle device equipped with the following features.

2. The pressure equalization valve is provided in a third refrigerant pipe that connects a first refrigerant pipe connecting the four-way valve and the accumulator, and a second refrigerant pipe connecting the compressor and the four-way valve. The expansion valve is provided in a fourth refrigerant pipe connecting the first heat exchanger, which is connected to the four-way valve by piping, and the second heat exchanger, which is also connected to the four-way valve by piping. The refrigeration cycle apparatus according to claim 1.

3. The temperature sensor is provided in the flow path of the suction pipe for connecting the accumulator to the compressor. A refrigeration cycle apparatus according to claim 1 or 2.

4. The determination means determines refrigerant leakage by comparing the time at which a singularity appears in the slope based on the time progression of the suction temperature of the suction pipe at the time of determination with the time at which a singularity appears in the slope based on the time progression of the suction temperature of the suction pipe at the reference time. The refrigeration cycle apparatus according to claim 3.

5. The determination means calculates the saturated evaporation temperature based on the suction pressure of the compressor and estimates the time at which the singularity appears by comparing the suction temperature of the suction pipe with the saturated evaporation temperature. The refrigeration cycle apparatus according to claim 4.

6. The temperature sensor is further provided in the flow path of the oil return pipe connected to the accumulator, which is part of the flow path of the suction pipe. The determination means determines the presence of refrigerant leakage based on the temperature data during the cooling operation process detected by each temperature sensor. The refrigeration cycle apparatus according to claim 3.

7. The temperature sensor is provided in the flow path of the second refrigerant piping among the flow paths. The refrigeration cycle apparatus according to claim 2.

8. The determination means determines refrigerant leakage by comparing the time at which a singularity appears in the slope based on the time progression of the discharge temperature of the second refrigerant piping at the time of determination with the time at which a singularity appears in the slope based on the time progression of the discharge temperature of the second refrigerant piping at the reference time. The refrigeration cycle apparatus according to claim 7.

9. The determination means determines the refrigerant leak based on the change in the rate of change of the discharge temperature of the second refrigerant piping. The refrigeration cycle apparatus according to claim 7.

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