WO2025083873A1 - Refrigeration cycle device and control method for refrigeration cycle device - Google Patents

Abstract

A refrigeration cycle device (101) comprises a compressor (1), an indoor heat exchanger (2), an expansion valve (3), an outdoor heat exchanger (4), piping (20), first bypass piping (31), a first valve (11), and a control device (50). The piping (20) connects the compressor (1), the indoor heat exchanger (2), the expansion valve (3), and the outdoor heat exchanger (4). The first valve (11) guides a refrigerant from the indoor heat exchanger (2) to the first bypass piping (31). The control device (50) controls the first valve (11). One end (31A) of the first bypass piping (31) is connected to piping (20A) that connects the indoor heat exchanger (2) and the expansion valve (3). The control device (50) opens the first valve (11) when operation of the refrigeration cycle device (101) has stopped.

Description

Refrigeration cycle device and method for controlling the refrigeration cycle device

This disclosure relates to a refrigeration cycle device and a method for controlling a refrigeration cycle device.

　Conventionally, refrigeration cycle devices equipped with a compressor that compresses and discharges a refrigerant are known. In general, when a refrigeration cycle device is started, if the difference between the pressure value of the refrigerant on the suction side of the compressor and the pressure value of the refrigerant on the discharge side is large, the compressor may break down.

　Assuming such a case, Patent Document 1 (JP 2000-55484 A) discloses a refrigeration cycle device that performs pressure equalization by making the pressure value of the refrigerant on the suction side of the compressor the same as the pressure value of the refrigerant on the discharge side. This refrigeration cycle device is equipped with a bypass path and an adjustment valve that opens and closes the bypass path. One end of the bypass path is connected to the piping on the discharge side of the refrigeration cycle device, and the other end of the bypass path is connected to the piping on the suction side of the refrigeration cycle device. When the operation of the compressor is stopped, the refrigeration cycle device opens the adjustment valve. When the adjustment valve is opened, the discharge side and suction side of the compressor are connected to each other, thereby performing the above-mentioned pressure equalization.

JP 2000-55484 A

In the above refrigeration cycle device, if the compressor stops while not operating fully, the liquid refrigerant that has not been able to move through the bypass path remains near the compressor. Therefore, if the compressor stops while not operating fully and the adjustment valve is opened, the remaining liquid refrigerant will infiltrate into the compressor via the one end of the bypass path. Therefore, the infiltrating liquid refrigerant will reduce the concentration of the refrigeration oil inside the compressor, which can cause the compressor to break down when it starts up.

The present disclosure has been made to solve these problems, and its purpose is to equalize the pressure of the refrigerant on the suction side and discharge side of the compressor while preventing liquid refrigerant from entering from the discharge side of the compressor.

The refrigeration cycle device of the present disclosure includes a compressor, a condenser, an expansion valve, an evaporator, piping, a first bypass piping, a first valve, and a control device. The piping connects the compressor, the condenser, the expansion valve, and the evaporator. The first valve guides refrigerant from the condenser to the first bypass piping. The control device controls the first valve. One end of the first bypass piping is connected to a piping that connects the condenser and the expansion valve. The control device opens the first valve when operation of the refrigeration cycle device stops.

The disclosed method is a control method for a refrigeration cycle device. The refrigeration cycle device includes a compressor, a condenser, an expansion valve, an evaporator, a pipe, a first bypass pipe, and a first valve. The pipe connects the compressor, the condenser, the expansion valve, and the evaporator. The first valve guides refrigerant from the condenser to the first bypass pipe. One end of the first bypass pipe is connected to a pipe connecting the condenser and the expansion valve. The control method opens the first valve when operation of the refrigeration cycle device stops.

According to the present disclosure, it is possible to equalize the pressure on the suction side and discharge side of the compressor while preventing liquid refrigerant from entering through the discharge side of the compressor.

1 is a diagram showing a configuration example of a refrigeration cycle device according to a first embodiment; 4 is a flowchart showing a process of the control device according to the first embodiment. FIG. 11 is a diagram showing a configuration example of a refrigeration cycle device according to a second embodiment. 10 is a diagram for explaining a method for determining whether or not the operating state of the refrigeration cycle device is in a stable state. FIG. 4 is a flowchart showing a process of the control device according to the embodiment.

The present embodiment will now be described in detail with reference to the drawings. Note that the same or corresponding parts in the drawings will be given the same reference numerals and their description will not be repeated.

Embodiment 1.
[Example of configuration of refrigeration cycle device]
Fig. 1 is a diagram showing a configuration example of a refrigeration cycle apparatus 101 according to a first embodiment. The refrigeration cycle apparatus 101 functions as an air-conditioning apparatus, for example. The configuration of the refrigeration cycle apparatus 101 according to the present embodiment will be described with reference to Fig. 1.

The refrigeration cycle device 101 performs at least one of a cooling operation and a heating operation. FIG. 1 is a diagram showing a case where the refrigeration cycle device 101 performs a heating operation. As shown in FIG. 1, the refrigeration cycle device 101 includes an outdoor unit 201 and an indoor unit 202. The outdoor unit 201 and the indoor unit 202 are connected by piping. The outdoor unit 201 mainly includes a compressor 1, an expansion valve 3, an outdoor heat exchanger 4, a first valve 11, and a first bypass piping 31. The indoor unit 202 mainly includes an indoor heat exchanger 2. In FIG. 1, the first bypass piping 31 is indicated by a thick line.

The compressor 1, indoor heat exchanger 2, expansion valve 3, and outdoor heat exchanger 4 are connected by piping 20. In FIG. 1, the piping connecting the indoor heat exchanger 2 and the expansion valve 3 is shown as piping 20A.

The refrigerant is used in a refrigeration cycle that transports heat between the outdoor unit 201 and the indoor unit 202. The refrigerant is, for example, a non-azeotropic refrigerant mixture. A non-azeotropic refrigerant mixture is a refrigerant that is a mixture of two or more refrigerants with different boiling points. An example of a non-azeotropic refrigerant mixture is R454C. The non-azeotropic refrigerant mixture may be another refrigerant. Furthermore, the non-azeotropic refrigerant mixture may be a mixture of three or more types of refrigerants.

In addition, during heating operation and with the first valve 11 closed, the refrigerant is configured to circulate through the compressor 1, indoor heat exchanger 2, expansion valve 3, outdoor heat exchanger 4, and compressor 1 in that order.

The compressor 1 is configured to compress and discharge the sucked refrigerant. During heating operation, the refrigerant discharged from the compressor 1 flows to the indoor heat exchanger 2. The indoor heat exchanger 2 exchanges heat between the refrigerant flowing inside the indoor heat exchanger 2 and the air in the first space (e.g., the indoor space) in which the indoor unit 202 is installed. The indoor heat exchanger 2 is configured to function as an evaporator that evaporates the refrigerant during cooling operation, and to function as a condenser that condenses the refrigerant during heating operation.

The refrigerant from the indoor heat exchanger 2 flows to the expansion valve 3. The expansion valve 3 is configured to reduce the pressure of the refrigerant condensed in the condenser (indoor heat exchanger 2) by expanding it. The expansion valve 3 is, for example, an electromagnetic expansion valve.

The outdoor heat exchanger 4 exchanges heat between the refrigerant flowing inside the outdoor heat exchanger 4 and the air in the second space (outdoor space) where the outdoor unit 201 is installed. The outdoor heat exchanger 4 is configured to function as a condenser that condenses the refrigerant during cooling operation, and to function as an evaporator that evaporates the refrigerant during heating operation.

The control device 50 is configured to control each device of the refrigeration cycle device 101. The control device 50 is electrically connected to the compressor 1, the expansion valve 3, the first valve 11, etc., and is configured to control the operation of these devices.

The control device 50 controls the compressor 1 and other components based on the set temperature and the indoor temperature. The set temperature is set by, for example, a user. The indoor temperature is the temperature of the space (room) in which the indoor unit 202 is installed. The control device 50 controls the compressor 1 and other components, for example, so that the indoor temperature approaches the set temperature. Specifically, the control device 50 controls the operating parameters of the motor of the compressor 1 in accordance with the thermal load (air conditioning load). The operating parameters are, for example, the operating frequency of the motor or the rotation speed of the motor. In this embodiment, the operating parameter is the operating frequency of the motor. For example, the control device 50 controls the operating frequency in accordance with the thermal load required to set the indoor temperature to the set temperature (to cool or heat the indoor temperature).

The control device 50 has as its main components a CPU (Central Processing Unit) 51 and a memory 52. The CPU 51 executes various processes and calculations. The components are interconnected by a data bus. The memory 52 includes a ROM (Read Only Memory) and a RAM (Random Access Memory), etc. The CPU 51 is also referred to as "at least one processor" or a "control circuit."

The ROM stores the programs executed by the CPU 51. The RAM temporarily stores data generated by the execution of the programs in the CPU 51. The RAM can function as a temporary data memory used as a work area. The control device 50 stores a mode flag indicating the operation mode in the RAM. When performing cooling operation, the control device 50 stores a cooling operation flag (mode flag) indicating the cooling operation in the RAM. When performing heating operation, the control device 50 stores a heating operation flag (mode flag) indicating the heating operation in the RAM.

If the refrigeration cycle device 101 is capable of performing both cooling and heating operations, a configuration including a four-way valve may be adopted. By switching this four-way valve, the refrigerant circulates in the following order in either cooling or heating operation: compressor 1, condenser, expansion valve 3, evaporator, compressor 1.

[Pressure equalization]
Next, the pressure equalization process will be described. If the refrigerant pressure on the discharge side 1A of the compressor 1 is significantly different from the refrigerant pressure on the suction side 1B of the compressor 1, the compressor 1 may break down due to reasons such as an increase in the driving torque at the start of the compressor 1. Therefore, the refrigeration cycle device 101 of this embodiment executes the pressure equalization process. The pressure equalization process is a process for equalizing the refrigerant pressure on the discharge side 1A of the compressor 1 and the refrigerant pressure on the suction side 1B of the compressor 1 (pressure equalization). By equalizing the refrigerant pressure on the discharge side 1A of the compressor 1 and the refrigerant pressure on the suction side 1B of the compressor 1, the breakdown of the compressor 1 can be suppressed. The pressure equalization process may be a process for approximately equalizing the refrigerant pressure on the discharge side 1A of the compressor 1 and the refrigerant pressure on the suction side 1B of the compressor 1. "Almost the same" means that the difference between the refrigerant pressure on the discharge side 1A of the compressor 1 and the refrigerant pressure on the suction side 1B of the compressor 1 is a value that can suppress a breakdown of the compressor 1. The pressure equalization process may also be expressed as "a process of reducing the difference between the refrigerant pressure on the discharge side 1A of the compressor 1 and the refrigerant pressure on the suction side 1B of the compressor 1."

　A conventional refrigeration cycle device is equipped with a bypass path and an adjustment valve that opens and closes the bypass path in order to perform the pressure equalization process. One end of the bypass path is connected to the discharge side of the refrigeration cycle device, and the other end of the bypass path is connected to the suction side of the refrigeration cycle device. When the operation of the compressor is stopped, the refrigeration cycle device opens the adjustment valve. By opening the adjustment valve, the discharge side and suction side of the compressor are connected to each other, and the above-mentioned pressure equalization process is performed.

However, in the above refrigeration cycle device, if the compressor stops while it is not operating sufficiently (for example, if the compressor is repeatedly turned on and off in a short period of time), the liquid refrigerant that has not been able to move through the bypass path remains near the compressor. Therefore, if the compressor stops while it is not operating sufficiently and the adjustment valve is opened, the remaining liquid refrigerant will infiltrate into the compressor via the one end of the bypass path. Therefore, the infiltrating liquid refrigerant will reduce the concentration of the refrigeration oil inside the compressor, which can cause the compressor to break down when it is started.

In this embodiment, one end 31A of the first bypass pipe 31 is connected to the pipe 20A that connects the indoor heat exchanger 2 (condenser) and the expansion valve 3. The first valve 11 is provided midway along the first bypass pipe 31. The first valve 11 is, for example, an expansion valve, and more typically, an electromagnetic expansion valve. The other end 31B of the first bypass pipe 31 is connected to the pipe on the suction side 1B of the compressor 1.

Then, when the operation of the refrigeration cycle device 101 (or the compressor 1) is stopped, the control device 50 executes a process of opening the first valve 11 (increasing the opening degree of the first valve 11). This process of opening the first valve 11 is a pressure equalization process (first pressure equalization process). This first pressure equalization process connects the piping from the discharge side 1A of the compressor 1 to the indoor heat exchanger 2, the piping from the indoor heat exchanger 2 to one end 31A of the first bypass piping 31, and the piping from the first bypass piping 31 to the suction side 1B of the compressor. All of the connected piping (the piping from the discharge side 1A of the compressor 1 to the indoor heat exchanger 2, the piping from the indoor heat exchanger 2 to one end 31A of the first bypass piping 31, and the piping from the first bypass piping 31 to the suction side 1B of the compressor) are collectively referred to as the "first connected piping."

The first valve 11 also guides the refrigerant (or at least a part of the refrigerant) from the indoor heat exchanger 2 to the first bypass pipe 31. When the operation of the refrigeration cycle device 101 (or the compressor 1) is stopped (when the first valve 11 is opened), the flow of the refrigerant discharged from the compressor 1 flows to the indoor heat exchanger 2 and branches at one end 31A. The branched refrigerant (first refrigerant) then flows to the first bypass pipe 31 (one end 31A, the first valve 11, the other end 31B). The remaining refrigerant (second refrigerant) at the one end 31A flows to the expansion valve 3. The first refrigerant from the other end 31B of the first bypass pipe 31 proceeds to at least one of the suction side of the compressor 1 and the outdoor heat exchanger 4. The second refrigerant that flows to the expansion valve 3 passes through the outdoor heat exchanger 4 and merges with the first refrigerant at the other end 31B.

In addition, as a method for the control device 50 to determine that the operation of the refrigeration cycle device 101 has been stopped, for example, when the operating frequency of the compressor 1 becomes zero, the compressor 1 outputs a stop signal to the control device 50. When the control device 50 receives the stop signal, it determines that the operation of the refrigeration cycle device 101 has been stopped.

As described above, when the operation of the refrigeration cycle apparatus 101 is stopped, the refrigeration cycle apparatus 101 opens the first valve 11 to communicate the first communication pipe. Therefore, while the operation of the refrigeration cycle apparatus 101 is stopped, the refrigeration cycle apparatus 101 can equalize the refrigerant pressure on the discharge side 1A of the compressor 1 and the refrigerant pressure on the suction side 1B of the compressor 1. Therefore, it is possible to suppress failure of the compressor 1 due to the difference between the refrigerant pressure on the discharge side 1A and the refrigerant pressure on the suction side 1B of the compressor 1.

Hereinafter, in the above-mentioned conventional refrigeration cycle device, the communicating piping when the regulating valve is opened is also referred to as the "conventional communicating piping". The communicating piping in this embodiment includes a piping from the compressor 1 to the indoor heat exchanger 2, so it can be longer than the conventional communicating piping. Therefore, even if the compressor 1 stops while the compressor 1 is not operating sufficiently, the liquid refrigerant can be kept in the first communicating piping, which is longer than the conventional communicating piping, so that the liquid refrigerant can be prevented from entering from the discharge side 1A of the compressor 1. As a result, the refrigeration cycle device 101 can prevent a decrease in the oil concentration of the refrigeration oil inside the compressor 1 and can prevent the compressor 1 from breaking down when the compressor 1 is started.

The other end 31B of the first bypass pipe 31 is connected to the pipe on the suction side 1B of the compressor 1. Therefore, the refrigeration cycle device 101 can return the refrigerant (first refrigerant) that has flowed through the first bypass pipe 31 to the compressor 1.

[flowchart]
Fig. 2 is a flowchart showing the process of the control device 50. The process of Fig. 2 is executed by the control device 50 at predetermined intervals (for example, one second). First, in step S2, the control device 50 detects the operation mode. The operation mode is a mode indicating whether the refrigeration cycle apparatus 101 (or the compressor 1) is operating or not.

Next, in step S4, the control device 50 determines whether operation has been stopped. If operation has been stopped (YES in step S4), in step S6, the control device 50 opens the first valve 11. Then, the process in FIG. 2 ends. Also, if operation has not been stopped in step S4 (NO in step S4), the process in FIG. 2 ends.

Embodiment 2.
3 is a diagram showing a configuration example of a refrigeration cycle apparatus 102 according to embodiment 2. In addition to the components of the refrigeration cycle apparatus 101, the refrigeration cycle apparatus 102 has a second bypass pipe 32, a second valve 12, a first pressure sensor 61, and a second pressure sensor 62. The second valve 12 is, for example, an expansion valve, and more typically, an electromagnetic expansion valve.

One end 32A of the second bypass pipe 32 is connected to the pipe on the discharge side 1A of the compressor 1. The other end 32B of the second bypass pipe 32 is connected to the pipe on the suction side 1B of the compressor 1. In the example of FIG. 3, the other end 31B and the other end 32B are connected.

When the operation of the refrigeration cycle device 102 (or the compressor 1) is stopped, the control device 50 executes a process of opening the second valve 12 (increasing the opening of the second valve 12). This process of opening the second valve 12 (increasing the opening of the second valve 12) is a pressure equalization process (second pressure equalization process). This second pressure equalization process connects the piping from the discharge side 1A of the compressor 1 to one end 32A of the second bypass piping 32, the piping from one end 32A to the other end 32B, and the piping from the other end 32B to the suction side 1B of the compressor 1. All of the connected piping (the piping from the discharge side 1A of the compressor 1 to one end 32A of the second bypass piping 32, the piping from one end 32A to the other end 32B, and the piping from the other end 32B to the suction side 1B of the compressor 1) are collectively referred to as the "second connected piping".

The second valve 12 also guides the refrigerant (or at least a portion of the refrigerant) discharged from the compressor 1 to the second bypass pipe 32. Therefore, when the second pressure equalization process is performed, the flow of the refrigerant discharged from the compressor 1 is compressor 1, second bypass pipe 32 (one end 32A, second valve 12, other end 32B).

The length of the second communication pipe is shorter than the length of the first communication pipe (see the explanation of the first embodiment). Therefore, when the second communication pipe is formed (when the first valve 11 is closed and the second valve 12 is open), the pressure equalization speed is faster than when the first communication pipe is formed (when the first valve 11 is open and the second valve 12 is closed). In other words, the second pressure equalization process has a faster pressure equalization speed than the first pressure equalization process. The pressure equalization speed refers to the amount of reduction per unit time of the difference between the refrigerant pressure on the discharge side 1A of the compressor 1 and the refrigerant pressure on the suction side 1B of the compressor 1. Note that in the first pressure equalization process, the pressure loss due to the expansion valve 3 can also be a factor in slowing down the pressure equalization speed.

When the second communication pipe is formed, the pressure equalization speed can be increased, but since the length of the second communication pipe is short, there is a concern that the refrigerant may infiltrate from the discharge side 1A of the compressor 1. Here, when the operating state of the refrigeration cycle device 102 (or the compressor 1) is stable, the refrigerant is a gas refrigerant. Even if the gas refrigerant infiltrates from the discharge side 1A of the compressor 1, the oil concentration of the refrigeration oil does not decrease, so no particular problem occurs. In addition, the refrigeration cycle device 102 is provided with a storage section (for example, a receiver, an accumulator, etc.) that stores liquid refrigerant. In FIG. 3, the storage section is not shown. When the operating state of the refrigeration cycle device 102 is stable, the liquid refrigerant is stored in the storage section. Therefore, when the operating state of the refrigeration cycle device 102 is stable, the liquid refrigerant is prevented from infiltrating from the discharge side 1A of the compressor 1.

Therefore, when the operation of the refrigeration cycle device 102 is stopped, if the operating state of the refrigeration cycle device 102 is stable, the second pressure equalization process (processing to close the first valve 11 and open the second valve 12) is performed. This allows the refrigeration cycle device 102 to achieve pressure equalization at a high pressure equalization speed while suppressing a decrease in the oil concentration of the refrigeration oil. On the other hand, when the operation of the refrigeration cycle device 102 is stopped, if the operating state of the refrigeration cycle device 102 is not stable (unstable), the refrigerant is likely to be liquid refrigerant. Therefore, in this case, the refrigeration cycle device 102 performs the first pressure equalization process (processing to open the first valve 11 and close the second valve 12). This allows the refrigeration cycle device 102 to achieve pressure equalization while suppressing the intrusion of liquid refrigerant from the discharge side 1A of the compressor 1.

Next, a method for determining whether the operating state of the refrigeration cycle device 102 is stable or not will be described. FIG. 4 is a diagram for explaining a method for determining whether the operating state of the refrigeration cycle device 102 is stable or not. In FIG. 4, first to fourth examples of this method are shown. In this second embodiment, the first example is applied. The second to fourth examples will be described later.

The refrigeration cycle device 102 is equipped with a sensor that detects an operating parameter related to the operation of the refrigeration cycle device 102. The control device 50 determines that the operating state of the refrigeration cycle device 102 is stable when the detected operating parameter is greater than a threshold value corresponding to the operating parameter.

In the second embodiment, the sensors are a first pressure sensor 61 and a second pressure sensor 62. The first pressure sensor 61 detects the refrigerant pressure (first pressure value) on the discharge side 1A of the compressor 1. The second pressure sensor 62 detects the refrigerant pressure (second pressure value) on the suction side 1B of the compressor 1. The operating parameters include a difference value between the first pressure value and the second pressure value.

The control device 50 acquires a first pressure value from the first pressure sensor 61 and a second pressure value from the second pressure sensor 62. The control device 50 then calculates a difference between the first pressure value and the second pressure value as an operating parameter. The control device 50 compares the difference with a threshold value (first threshold value) corresponding to the difference value, and if the difference value is greater than the first threshold value, determines that the operating state of the refrigeration cycle device 102 is stable. On the other hand, if the difference value is smaller than the first threshold value, the control device 50 determines that the operating state of the refrigeration cycle device 102 is unstable. Note that if the difference value is the same as the first threshold value, the control device 50 may determine that the operating state of the refrigeration cycle device 102 is stable or unstable.

FIG. 5 is a flowchart showing the processing of the control device of the second embodiment. After the processing of step S2, in step S104, the control device 50 detects the operating state (stable state and unstable state) of the refrigeration cycle device 102. This detection of the operating state is performed based on the above operating parameters.

If it is determined in step S4 that the refrigeration cycle apparatus 102 has stopped operating, then in step S108 the control device 50 determines whether the operating state of the refrigeration cycle apparatus 102 is stable or not based on the detection result in step S104. If the operating state is stable in step S108 (YES in step S108), then in step S110 the control device 50 executes the second pressure equalization process (i.e., a process of opening the second valve 12 and closing the first valve 11). Then, the process in FIG. 5 ends.

On the other hand, if the operating state is unstable in step S108 (NO in step S108), the control device 50 executes the first pressure equalization process (i.e., a process of closing the second valve 12 and opening the first valve 11) in step S112. Then, the process in FIG. 5 ends.

As described above, the refrigeration cycle apparatus 102 of this embodiment includes the second bypass pipe 32 and the second valve 12. The refrigeration cycle apparatus 102 performs the second pressure equalization process using the second bypass pipe 32 and the second valve 12. The refrigeration cycle apparatus 102 performs either the first pressure equalization process or the second pressure equalization process depending on whether the operating state of the refrigeration cycle apparatus 102 is stable or unstable when the operation of the refrigeration cycle apparatus 102 is stopped. Specifically, when the operation of the refrigeration cycle apparatus 102 is stopped, the refrigeration cycle apparatus 102 performs the second pressure equalization process (processing to open the second valve 12) when the operating state of the refrigeration cycle apparatus 102 is stable. This allows the refrigeration cycle apparatus 102 to achieve pressure equalization at a high pressure equalization speed.

The second pressure equalization process is a process in which the second valve 12 is opened and the first valve 11 is closed. Therefore, the refrigeration cycle device 102 can appropriately perform the second pressure equalization process.

In addition, when the operation of the refrigeration cycle device 102 is stopped and the operating state of the refrigeration cycle device 102 is unstable, the refrigeration cycle device 102 executes the first pressure equalization process (processing to open the first valve 11). This allows the refrigeration cycle device 102 to achieve pressure equalization while suppressing the intrusion of liquid refrigerant from the discharge side 1A of the compressor 1.

The first pressure equalization process is a process in which the second valve 12 is closed and the first valve 11 is opened. Therefore, the refrigeration cycle device 102 can appropriately perform the first pressure equalization process.

Furthermore, when the operating parameter is greater than a threshold value corresponding to the operating parameter, the refrigeration cycle device 102 determines that the operating state of the refrigeration cycle device 102 is stable. Therefore, the refrigeration cycle device 102 can appropriately determine that the operating state of the refrigeration cycle device 102 is stable.

The refrigeration cycle device 102 also has, as the above sensors, a first pressure sensor 61 that detects a first pressure value and a second pressure sensor 62 that detects a second pressure value. The control device 50 then uses the difference value between the first pressure value and the second pressure value as an operating parameter. This allows the refrigeration cycle device 102 to appropriately determine that the operating state of the refrigeration cycle device 102 is stable, with a relatively simple configuration.

Next, the second to fourth examples of FIG. 4 will be described. The control device 50 to which the second example is applied is equipped with a timer 151 (see dashed line in FIG. 3) that detects the operation time of the refrigeration cycle device 102 as the above-mentioned sensor. The operation time is, for example, the time from when the operation of the refrigeration cycle device 102 starts to when the operation of the refrigeration cycle device 102 ends. The above-mentioned operation parameters of the refrigeration cycle device 102 to which the second example is applied include the operation time detected by the timer 151.

Then, when the operating time is greater than a second threshold value corresponding to the operating time, the refrigeration cycle device 102 determines that the operating state of the refrigeration cycle device 102 is stable. On the other hand, when the operating time is less than this second threshold value, the refrigeration cycle device 102 determines that the operating state of the refrigeration cycle device 102 is unstable. In the refrigeration cycle device 102 to which this second example is applied, the operating state of the refrigeration cycle device 102 can be determined with a relatively simple configuration.

The refrigeration cycle device 102 to which the third example is applied is equipped with a superheat sensor 152 (see dashed line in FIG. 3) that detects the degree of superheat of the refrigerant on the discharge side of the compressor as the above sensor. The degree of superheat is the difference between the temperature of the refrigerant on the discharge side 1A and the saturation temperature at the pressure of the refrigerant. The above operating parameters of the refrigeration cycle device 102 to which the third example is applied include the degree of superheat of the refrigerant detected by the superheat sensor 152. The control device 50 obtains the degree of superheat from the superheat sensor 152.

Then, when the degree of superheat of the refrigerant is greater than a third threshold value corresponding to the degree of superheat, the refrigeration cycle device 102 determines that the operating state of the refrigeration cycle device 102 is stable. On the other hand, when the degree of superheat is less than the third threshold value, the refrigeration cycle device 102 determines that the operating state of the refrigeration cycle device 102 is unstable. In the refrigeration cycle device 102 to which this third example is applied, the operating state of the refrigeration cycle device 102 can be determined with a relatively simple configuration.

The refrigeration cycle device 102 to which the fourth example is applied is equipped with a subcooling degree sensor 153 (see dashed line in Figure 3) that detects the degree of subcooling of the refrigerant on the discharge side of the compressor as the above sensor. The degree of subcooling is the difference between the temperature of the refrigerant on the outlet side of the indoor heat exchanger 2 and the saturation temperature of the refrigerant. The above operating parameters of the refrigeration cycle device 102 to which the fourth example is applied include the degree of subcooling of the refrigerant detected by the subcooling degree sensor 153. The control device 50 obtains the degree of subcooling from the subcooling degree sensor 153.

Then, when the degree of subcooling of the refrigerant is greater than a fourth threshold value corresponding to the degree of subcooling, the refrigeration cycle device 102 determines that the operating state of the refrigeration cycle device 102 is stable. On the other hand, when the degree of subcooling is less than the fourth threshold value, the refrigeration cycle device 102 determines that the operating state of the refrigeration cycle device 102 is unstable. In the refrigeration cycle device 102 to which the fourth example is applied, the operating state of the refrigeration cycle device 102 can be determined with a relatively simple configuration.

In the above example, the other end 31B of the first bypass pipe 31 is connected to the pipe on the suction side 1B of the compressor 1. However, the other end 31B may be connected to another location.

[summary]
(Item 1) The refrigeration cycle apparatus of the present disclosure includes a compressor, a condenser, an expansion valve, an evaporator, a pipe, a first bypass pipe, a first valve, and a control device. The pipe connects the compressor, the condenser, the expansion valve, and the evaporator. The first valve guides refrigerant from the condenser to the first bypass pipe. The control device controls the first valve. One end of the first bypass pipe is connected to a pipe connecting the condenser and the expansion valve. The control device opens the first valve when operation of the refrigeration cycle apparatus stops.

(2) The refrigeration cycle device according to 1, further comprising a second bypass pipe and a second valve for directing the refrigerant discharged from the compressor to the second bypass pipe. One end of the second bypass pipe is connected to a pipe on the discharge side of the compressor. The other end of the second bypass pipe is connected to a pipe on the suction side of the compressor. When the operation of the refrigeration cycle device is stopped, the control device opens the second valve if the operating state of the refrigeration cycle device is stable.

(Clause 3) In the refrigeration cycle device described in Clause 2, when the operation of the refrigeration cycle device is stopped, the control device opens the second valve and closes the first valve if the operating state of the refrigeration cycle device is stable.

(4) In the refrigeration cycle device described in 2 or 3, the control device opens the first valve when the operation of the refrigeration cycle device is stopped and the operating state of the refrigeration cycle device is not stable.

(5) In the refrigeration cycle device described in 4, when the operation of the refrigeration cycle device is stopped, the control device opens the first valve and closes the second valve if the operating state of the refrigeration cycle device is not stable.

(6) The refrigeration cycle device according to any one of paragraphs 2 to 5, further comprising a sensor for detecting a parameter related to the operation of the refrigeration cycle device. The control device determines that the operation state of the refrigeration cycle device is stable when the parameter is greater than a threshold value corresponding to the parameter.

(7) A refrigeration cycle device according to 6, wherein the sensor includes a first pressure sensor that detects a first pressure value of the refrigerant on the discharge side of the compressor, and a second pressure sensor that detects a second pressure value of the refrigerant on the suction side of the compressor. The parameter includes a difference value between the first pressure value and the second pressure value.

(8) In the refrigeration cycle device described in 6 or 7, the sensor includes a timer that detects the operation time of the refrigeration cycle device. The parameters include the operation time.

(Item 9) In the refrigeration cycle device described in any one of Items 6 to 8, the sensor includes a superheat sensor that detects the degree of superheat of the refrigerant on the discharge side of the compressor. The parameters include the degree of superheat.

(10) A refrigeration cycle device according to any one of paragraphs 6 to 9, wherein the sensor includes a subcooling degree sensor that detects the degree of subcooling of the refrigerant on the outlet side of the condenser. The parameters include the degree of subcooling.

(11) A refrigeration cycle device as described in any one of paragraphs 1 to 10, in which the other end of the first bypass pipe is connected to the suction side pipe of the compressor.

(Item 12) The method disclosed herein is a method for controlling a refrigeration cycle device. The refrigeration cycle device includes a compressor, a condenser, an expansion valve, an evaporator, piping, a first bypass piping, and a first valve. The piping connects the compressor, the condenser, the expansion valve, and the evaporator. The first valve guides refrigerant from the condenser to the first bypass piping. One end of the first bypass piping is connected to a piping that connects the condenser and the expansion valve. The control method opens the first valve when operation of the refrigeration cycle device stops.

The embodiments disclosed herein should be considered in all respects as illustrative and not restrictive. The scope of the present disclosure is indicated by the claims, not the above description, and is intended to include all modifications within the meaning and scope of the claims.

1 compressor, 1A discharge side, 1B suction side, 2 indoor heat exchanger, 3 expansion valve, 4 outdoor heat exchanger, 11 first valve, 12 second valve, 20, 20A piping, 31 first bypass piping, 31A, 32A one end, 31B, 32B other end, 32 second bypass piping, 50 control device, 52 memory, 61 first pressure sensor, 62 second pressure sensor, 101, 102 refrigeration cycle device, 151 timer, 152 superheat sensor, 153 subcool sensor, 201 outdoor unit, 202 indoor unit.

Claims (12)

A refrigeration cycle device,
A compressor, a condenser, an expansion valve, and an evaporator.
a pipe connecting the compressor, the condenser, the expansion valve, and the evaporator;
A first bypass pipe;
a first valve for directing the refrigerant from the condenser to the first bypass pipe;
a control device for controlling the first valve,
one end of the first bypass pipe is connected to a pipe connecting the condenser and the expansion valve,
The control device opens the first valve when operation of the refrigeration cycle device stops. The refrigeration cycle device further comprises:
A second bypass pipe;
a second valve for guiding the refrigerant discharged from the compressor to the second bypass pipe,
One end of the second bypass pipe is connected to a pipe on a discharge side of the compressor,
The other end of the second bypass pipe is connected to a pipe on the intake side of the compressor,
The refrigeration cycle apparatus according to claim 1 , wherein the control device opens the second valve when an operating state of the refrigeration cycle apparatus is stable when operation of the refrigeration cycle apparatus is stopped. The refrigeration cycle device according to claim 2, wherein the control device opens the second valve and closes the first valve when the operation state of the refrigeration cycle device is in the stable state when the operation of the refrigeration cycle device is stopped. The refrigeration cycle device according to claim 2 or 3, wherein the control device opens the first valve when the operation state of the refrigeration cycle device is not in the stable state when the operation of the refrigeration cycle device is stopped. The refrigeration cycle device according to claim 4, wherein the control device opens the first valve and closes the second valve when the operation state of the refrigeration cycle device is not in the stable state when the operation of the refrigeration cycle device is stopped. The refrigeration cycle apparatus further includes a sensor for detecting a parameter related to an operation of the refrigeration cycle apparatus,
The refrigeration cycle device according to any one of claims 2 to 5, wherein the control device determines that the operating state of the refrigeration cycle device is in the stable state when the parameter is greater than a threshold value corresponding to the parameter. The sensor includes:
a first pressure sensor for detecting a first pressure value of a refrigerant on a discharge side of the compressor;
a second pressure sensor for detecting a second pressure value of the refrigerant on the suction side of the compressor,
The refrigeration cycle apparatus according to claim 6 , wherein the parameter includes a difference value between the first pressure value and the second pressure value. The sensor includes a timer that detects an operation time of the refrigeration cycle device,
The refrigeration cycle apparatus according to claim 6 or 7, wherein the parameters include the operation time. The sensor includes a superheat sensor that detects a superheat degree of the refrigerant on the discharge side of the compressor,
The refrigeration cycle apparatus according to any one of claims 6 to 8, wherein the parameters include the degree of superheat. the sensor includes a subcooling degree sensor that detects a subcooling degree of the refrigerant on an outlet side of the condenser,
The refrigeration cycle device according to any one of claims 6 to 9, wherein the parameters include the degree of subcooling. The refrigeration cycle device according to any one of claims 1 to 10, wherein the other end of the first bypass piping is connected to the piping on the intake side of the compressor. A method for controlling a refrigeration cycle device, comprising:
The refrigeration cycle device includes:
A compressor, a condenser, an expansion valve, and an evaporator.
a pipe connecting the compressor, the condenser, the expansion valve, and the evaporator;
A first bypass pipe;
a first valve for directing the refrigerant from the condenser to the first bypass pipe,
one end of the first bypass pipe is connected to a pipe connecting the condenser and the expansion valve,
The control method for a refrigeration cycle apparatus, wherein the first valve is opened when operation of the refrigeration cycle apparatus is stopped.

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