JP6072178B1 - Refrigeration cycle equipment - Google Patents

Abstract

In a refrigeration cycle apparatus in which lubricating oil circulates together with a refrigerant, an amount of oil returned to a compressor is increased while suppressing a liquid back phenomenon when returning from a defrost operation to a heating operation. A refrigeration cycle apparatus includes a refrigerant circuit and a control device. The refrigerant circuit includes a compressor, a first heat exchanger, a second heat exchanger, a refrigerant container, a first pressure reducing device, a second pressure reducing device, a four-way valve, the inside of the refrigerant container, and the compressor. A bypass channel connecting the suction side and a third decompression device provided on the bypass channel are provided. During the heating operation in which the compressor is operated with the four-way valve in the heating cycle state, the control device performs a defrost operation in which the four-way valve is in the cooling cycle state in order to remove frost attached to the first heat exchanger. When the defrost operation is completed, the control device performs a refrigerant recovery operation in which the third pressure reducing device is opened and the second pressure reducing device is closed while the four-way valve is maintained in the cooling cycle state. [Selection] Figure 6

Description

  The present invention relates to a refrigeration cycle apparatus, and more particularly to a refrigeration cycle apparatus in which lubricating oil circulates together with a refrigerant.

  Conventionally, in a refrigeration cycle apparatus, during a heating operation, a defrost operation (defrosting operation) in which the operation is temporarily switched from a heating operation to a cooling operation in order to remove frost attached to the outdoor heat exchanger is performed. There is.

  JP 2014-152937 A (Patent Document 1) includes a compressor, a four-way valve, an outdoor heat exchanger, an outdoor heat exchange side expansion valve, a refrigerant container, an indoor heat exchange side expansion valve, an indoor heat exchanger, In a refrigeration cycle apparatus comprising a refrigerant circuit connected in the order of a four-way valve and a compressor, a bypass pipe connecting a refrigerant container and a suction side of the compressor, and a regulating valve provided on the bypass pipe, during a defrost operation It is disclosed that the regulating valve is opened to discharge the gas refrigerant in the refrigerant container to the bypass pipe.

JP 2014-152937 A

  In the refrigeration cycle apparatus disclosed in Patent Document 1, the liquid refrigerant accumulated in the outdoor heat exchanger is easily collected in the refrigerant container by opening the regulating valve and degassing the refrigerant container during the defrost operation. . As a result, the amount of liquid refrigerant that accumulates in the outdoor heat exchanger decreases, and therefore, when returning from the defrost operation to the heating operation, a large amount of liquid refrigerant returns from the outdoor heat exchanger to the compressor (hereinafter referred to as “liquid back phenomenon”). ")" Can be suppressed.

  However, since a large amount of lubricating oil stays with the liquid refrigerant in the refrigerant container, there is a concern that poor lubrication of the compressor is likely to occur. In other words, lubricating oil (hereinafter, also simply referred to as “oil”) exists in the compressor in order to ensure the lubricity of the compressor. When the compressor is operated, oil is taken out to the refrigerant circuit together with the refrigerant compressed by the compressor. The oil taken out to the refrigerant circuit circulates through the refrigerant circuit together with the refrigerant and returns to the compressor. However, in the refrigeration cycle apparatus disclosed in Patent Document 1, since a large amount of oil and liquid refrigerant stay in the refrigerant container during the defrost operation, the oil taken out from the compressor to the refrigerant circuit returns to the compressor. There is a concern that poor lubrication of the compressor is likely to occur.

  The present invention has been made to solve the above-described problems, and its object is to suppress a liquid back phenomenon when returning from a defrost operation to a heating operation in a refrigeration cycle apparatus in which lubricating oil circulates together with a refrigerant. However, it is to increase the amount of oil returned to the compressor.

  A refrigeration cycle apparatus according to the present invention is a refrigeration cycle apparatus in which lubricating oil circulates together with a refrigerant, and performs heat exchange between a compressor provided between a suction passage and a discharge passage, and air and the refrigerant. A first heat exchanger, a second heat exchanger for exchanging heat between the air and the refrigerant, a refrigerant container provided on a refrigerant flow path connecting the first heat exchanger and the second heat exchanger, A first pressure reducing device provided on the refrigerant flow path connecting the first heat exchanger and the refrigerant container; a second pressure reducing device provided on the refrigerant flow path connecting the second heat exchanger and the refrigerant container; A cooling cycle state in which the flow path is connected to the second heat exchanger and the discharge flow path is connected to the first heat exchanger, and the suction flow path is connected to the first heat exchanger and the discharge flow path is the second heat exchange A switching device configured to be switchable to any state of the heating cycle state connected to the appliance; A bypass channel connecting the inside of the medium container and the suction channel, a third pressure reducing device provided on the bypass channel, and a switching device during a heating operation in which the compressor is operated with the switching device in a heating cycle state And a control device for switching to a defrost operation in which the air conditioner is in a cooling cycle state. When the defrosting operation is completed, the control device performs a refrigerant recovery operation in which the third decompression device is opened and the second decompression device is closed while the switching device is maintained in the cooling cycle state. Return to the state and return to heating operation.

  In this refrigeration cycle apparatus, when the defrost operation is completed, the refrigerant recovery operation is performed before returning to the heating operation (before returning the switching device to the heating cycle state).

  During the refrigerant recovery operation, the third pressure reducing device is opened and the second pressure reducing device is closed while the switching device is maintained in the cooling cycle state, so that the refrigerant discharged from the compressor is the first heat exchanger, 1 It flows in order of a decompression device, a refrigerant container, a bypass channel, and a switching device, and is returned to a compressor. At this time, the liquid refrigerant accumulated in the first heat exchanger during the defrosting operation is decompressed by the first decompression device and then sent to the refrigerant container. Of the refrigerant sent to the refrigerant container, the gas medium flows into the bypass flow path and returns to the compressor, but the liquid refrigerant stays in the refrigerant container. That is, the liquid refrigerant collected in the first heat exchanger is recovered in the refrigerant container by the refrigerant recovery operation. Thereby, since the quantity of the liquid refrigerant in a 1st heat exchanger decreases, the liquid back phenomenon at the time of returning from a defrost operation to heating operation is suppressed.

  Furthermore, since the second decompression device is closed during the refrigerant recovery operation, the refrigerant does not flow through the second decompression device and the second heat exchanger and is temporarily switched to a shorter refrigerant circuit than during the defrost operation. Become. As a result, the concentration of the lubricating oil in the mixed liquid of the refrigerant and oil in the refrigerant container is increased, and the mixed liquid having a high oil concentration is easily collected in the refrigerant container. Therefore, it is possible to return the mixed liquid with a high oil concentration collected in the refrigerant container to the compressor from the bypass flow path. Therefore, the amount of oil returned to the compressor can be increased.

It is a whole refrigeration cycle apparatus block diagram (the 1). It is FIG. (1) which shows typically the internal structure of a refrigerant | coolant container. It is a figure which shows an example of two-phase separation temperature. It is a flowchart (the 1) which shows the process sequence of a control apparatus. It is a figure which shows the flow of the refrigerant | coolant during heating operation. It is a flowchart (the 2) which shows the process sequence of a control apparatus. It is a figure which shows the flow of the refrigerant | coolant in a defrost driving | operation. It is a figure which shows the flow of the refrigerant | coolant during a refrigerant | coolant collection | recovery driving | operation. It is a whole refrigeration cycle apparatus block diagram (the 2). It is a flowchart (the 3) which shows the process sequence of a control apparatus. It is a flowchart (the 4) which shows the process sequence of a control apparatus. It is a figure which shows the flow of the refrigerant | coolant in a refrigerant | coolant container, and the flow of oil. It is FIG. (2) which shows the internal structure of a refrigerant | coolant container typically.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. Hereinafter, a plurality of embodiments will be described. However, it is planned from the beginning of the application to appropriately combine the configurations described in the embodiments. In the drawings, the same or corresponding portions are denoted by the same reference numerals and description thereof will not be repeated.

[Embodiment 1]
<Configuration of refrigeration cycle apparatus>
FIG. 1 is an overall configuration diagram of a refrigeration cycle apparatus 200 according to the present embodiment. The refrigeration cycle apparatus 200 includes a refrigerant circuit in which lubricating oil (hereinafter also simply referred to as “oil”) circulates together with the refrigerant, and the control device 100. The refrigerant circuit includes a compressor 1, a four-way valve (switching device) 2, a first heat exchanger (outdoor heat exchanger) 3, a first decompression device 4, a refrigerant container 5, a second decompression device 6, and a second heat exchanger. (Indoor heat exchanger) 7, a bypass flow path 8, a third decompression device 9, a merging portion 10, a suction flow path 22, a discharge flow path 23, and refrigerant flow paths 24 to 27. The refrigeration cycle apparatus 200 further includes temperature sensors 101 and 102.

  The suction flow path 22 connects the compressor 1 and the four-way valve 2. The discharge flow path 23 connects the compressor 1 and the four-way valve 2 through a path different from the suction flow path 22. The refrigerant flow path 24 connects the four-way valve 2 and the first heat exchanger 3. The refrigerant flow path 25 connects the first heat exchanger 3 and the refrigerant container 5. The refrigerant channel 26 connects the refrigerant container 5 and the second heat exchanger 7. The refrigerant flow path 27 connects the second heat exchanger 7 and the four-way valve 2.

  The compressor 1 compresses the refrigerant sucked from the suction flow path 22 and discharges it to the discharge flow path 23. The operation amount (rotational speed and the like) of the compressor 1 is controlled according to a control signal from the control device 100.

  The four-way valve 2 is configured to be switchable between a cooling cycle state (see the solid line in FIG. 1) and a heating cycle state (see the broken line in FIG. 1) in accordance with a control signal from the control device 100. . When the four-way valve 2 is in the cooling cycle state, the suction passage 22 is connected to the refrigerant passage 27 (second heat exchanger 7), and the discharge passage 23 is the refrigerant passage 24 (first heat exchanger 3). Connected to. When the four-way valve 2 is in the heating cycle state, the suction flow path 22 is connected to the refrigerant flow path 24 (first heat exchanger 3), and the discharge flow path 23 is the refrigerant flow path 27 (second heat exchanger 7). Connected to.

  The first heat exchanger 3 performs heat exchange between outdoor air and the refrigerant. The first heat exchanger 3 functions as an evaporator during a heating operation described later, and functions as a condenser during a defrost operation and a refrigerant recovery operation described later.

  The first pressure reducing device 4 is a throttle valve provided on the refrigerant flow path 25. The opening degree of the first decompression device 4 is controlled according to a control signal from the control device 100.

  The refrigerant container 5 is provided between the first decompression device 4 and the second decompression device 6 and stores liquid refrigerant. The configuration of the refrigerant container 5 will be described in detail later.

  The second decompression device 6 is a throttle valve provided on the refrigerant flow path 26. The opening degree of the second decompression device 6 is controlled according to a control signal from the control device 100.

  The second heat exchanger 7 performs heat exchange between the indoor air and the refrigerant. The second heat exchanger 7 functions as a condenser during a heating operation described later and functions as an evaporator during a defrost operation described later.

  The bypass channel 8 connects the inside of the refrigerant container 5 and the suction channel 22. One end of the bypass channel 8 is inserted into the refrigerant container 5, and the other end of the bypass channel 8 is connected to the suction channel 22 at the junction 10.

  The third pressure reducing device 9 is a throttle valve provided on the bypass flow path 8. The opening degree of the third decompression device 9 is controlled according to a control signal from the control device 100.

  The temperature sensor 101 detects the liquid pipe temperature of the first heat exchanger 3. The temperature sensor 102 detects the temperature of the side surface of the refrigerant container 5 (see FIG. 2 described later). These sensors output detection results to the control device 100.

  The control device 100 includes a CPU (Central Processing Unit), a storage device, an input / output buffer, and the like (all not shown), and controls each device in the refrigeration cycle apparatus 200 according to the detection result of each sensor. Specifically, the control device 100 controls the operation of the compressor 1, the state of the four-way valve 2, the opening degree of the first decompression device 4, the opening degree of the second decompression device 6, and the opening degree of the third decompression device 9. To do. Note that these controls are not limited to processing by software, and can be processed by dedicated hardware (electronic circuit).

  FIG. 2 is a diagram schematically showing the internal structure of the refrigerant container 5. Inside the refrigerant container 5, a gas refrigerant and a liquid refrigerant containing oil (a liquid mixture of liquid refrigerant and oil) are stored. Due to the specific gravity, the gas refrigerant stays above the liquid refrigerant (mixed liquid). As will be described later, the oil may not be dissolved in the liquid refrigerant but may be separated from the liquid refrigerant and stay in the upper part of the liquid refrigerant and in the lower part of the gas refrigerant.

  Each of the refrigerant flow path 25, the refrigerant flow path 26, and the bypass flow path 8 has a portion provided inside the refrigerant container 5. Specifically, each of the refrigerant flow path 25, the refrigerant flow path 26, and the bypass flow path 8 passes through the upper surface 5 b inside the refrigerant container 5 and extends in a direction toward the bottom surface 5 a inside the refrigerant container 5. Has a part.

  The lower end 25a of the refrigerant passage 25, the lower end 26a of the refrigerant passage 26, and the lower end 8a of the bypass passage 8 are all open so as to function as refrigerant inlets. Both the lower end 25a of the refrigerant flow path 25 and the lower end 26a of the refrigerant flow path 26 are disposed at a position lower than the upper surface 5b inside the refrigerant container 5 and higher than the bottom surface 5a.

  The lower end 8 a of the bypass flow path 8 is disposed at a position lower than the upper surface 5 b inside the refrigerant container 5 and higher than the lower end 25 a of the refrigerant flow path 25 and the lower end 26 a of the refrigerant flow path 26. Therefore, the gas refrigerant flows through the bypass flow path 8 but the mixed liquid does not flow until the level of the liquid refrigerant in the refrigerant container 5 reaches the lower end 8a of the bypass flow path 8. On the other hand, when the liquid level of the liquid refrigerant reaches the lower end 8a of the bypass flow path 8, the mixed liquid flows through the bypass flow path 8, but the gas refrigerant does not flow.

  The height from the bottom surface 5a of the lower end 8a of the bypass channel 8 can suppress the liquid back phenomenon (a phenomenon in which a large amount of liquid refrigerant returns from the first heat exchanger 3 to the compressor 1) when returning to the heating operation. The amount of liquid refrigerant is determined so as to be recovered from the first heat exchanger 3 to the refrigerant container 5 by the refrigerant recovery operation described later.

  The temperature sensor 102 is installed at a specified position on the side surface of the refrigerant container 5. In the present embodiment, the specified position is set to a position higher by a predetermined amount α (α> 0) than the height from the bottom surface 5 a of the lower end 8 a of the bypass flow path 8. In addition, by adjusting the magnitude of the predetermined amount α, it is possible to adjust the amount of liquid mixture (the amount of oil returned to the compressor 1) that is returned from the refrigerant container 5 to the compressor 1 by the refrigerant recovery operation described later.

  The temperature detected by the temperature sensor 102 is different depending on whether the gas refrigerant is present at the specified position in the refrigerant container 5, the liquid refrigerant is present, or the oil is present. Therefore, when the temperature detected by the temperature sensor 102 is a value corresponding to the gas refrigerant, it can be determined that the gas refrigerant exists at the specified position. When the temperature detected by the temperature sensor 102 is a value corresponding to the liquid refrigerant, it can be determined that the liquid refrigerant exists at the specified position. When the temperature detected by the temperature sensor 102 is a value corresponding to oil, it can be determined that oil is present at the specified position.

  The temperature sensor 102 may be a temperature sensor with a heater. In this case, the refrigerant container 5 is utilized by utilizing the difference in heat transmission (response during heating) when oil is present at the specified position in the refrigerant container 5 and when there is liquid and when there is gas. It is possible to determine whether gas refrigerant, liquid refrigerant, or oil is present at the specified position by detecting a response when the heater is heated by the heater with the temperature sensor 102.

  In the present embodiment, the case where the third decompression device 9 is disposed on the bypass flow path 8 outside the refrigerant container 5 is illustrated, but the third decompression device 9 is configured to connect and block the bypass flow path 8. Any device that can be switched may be used, and the device may be disposed on the bypass channel 8 inside the refrigerant container 5. Further, the third decompression device 9 may be an apparatus that has a function of blocking the refrigerant flow path 26 when the bypass flow path 8 is communicated and communicating the refrigerant flow path 26 when the bypass flow path 8 is blocked. Good.

  FIG. 3 is a diagram illustrating an example of a temperature at which the liquid refrigerant and oil start to separate (hereinafter “two-phase separation temperature”). In FIG. 3, the horizontal axis indicates the oil concentration in the liquid refrigerant, and the vertical axis indicates the temperature of the liquid refrigerant.

  As shown in FIG. 3, the two-phase separation temperature has a characteristic that varies depending on the oil concentration. In the region where the temperature of the liquid refrigerant is higher than the two-phase separation temperature, the oil dissolves in the liquid refrigerant. On the other hand, in the region where the temperature of the mixed liquid is lower than the two-phase separation temperature, the oil stays in the upper layer of the liquid refrigerant in a state of being separated from the liquid refrigerant. Hereinafter, a region where oil is dissolved in the liquid refrigerant (region where the temperature is higher than the two-phase separation temperature in FIG. 3) is also referred to as “dissolution region”, and a region where oil is separated from the liquid refrigerant (from the two-phase separation temperature in FIG. 3). Is also referred to as “two-phase separation region”.

<Control of refrigeration cycle apparatus 200>
Hereinafter, control of the refrigeration cycle apparatus 200 by the control apparatus 100 will be described. Control device 100 performs the heating operation when there is a heating request (for example, when the user performs an operation for requesting heating). When frost adheres to the first heat exchanger 3 during the heating operation, the control device 100 temporarily switches to the defrost operation (defrost operation). When the defrost operation is completed, the control device 100 switches to the refrigerant recovery operation, and returns to the heating operation after the refrigerant recovery operation is completed. Hereinafter, the contents of the heating operation, the defrost operation, and the refrigerant recovery operation will be described in detail.

<< Heating operation >>
FIG. 4 is a flowchart showing a processing procedure when the control device 100 performs the heating operation. This flowchart is repeatedly executed at a predetermined cycle.

  In step (hereinafter, step is abbreviated as “S”) 10, control device 100 operates compressor 1 with four-way valve 2 in a heating cycle state.

  In S11, control device 100 controls the opening degree of first decompression device 4 and the opening degree of second decompression device 6 so that refrigeration cycle apparatus 200 exhibits a desired heating performance. For example, the control device 100 controls the first decompression device 4 so that the superheat degree (SH) of the refrigerant output from the first heat exchanger 3 (evaporator) to the compressor 1 becomes the target value, and the second The second decompression device 6 is controlled such that the degree of supercooling (SC) of the refrigerant output from the heat exchanger 7 (condenser) to the second decompression device 6 becomes a target value. The degree of superheat (SH) can be converted from the discharge temperature and pressure of the compressor 1. The degree of supercooling (SC) can be converted from the outlet temperature of the second heat exchanger 7 and the intermediate pressure.

  In S12, control device 100 determines whether or not the temperature of refrigerant container 5 (the temperature detected by temperature sensor 102) is included in the two-phase separation region shown in FIG. For example, the control device 100 estimates the oil concentration from the temperature of the refrigerant container 5 (the temperature detected by the temperature sensor 102), and obtains the two-phase separation temperature corresponding to the estimated oil concentration. And the control apparatus 100 determines with the temperature of the refrigerant | coolant container 5 being contained in a two-phase separation area | region, when the temperature (detection temperature of the temperature sensor 102) of the refrigerant | coolant container 5 is less than two-phase separation temperature.

  If the temperature of refrigerant container 5 is not included in the two-phase separation region (NO in S12), it is estimated that oil is dissolved in the liquid refrigerant in refrigerant container 5, and control device 100 ends the process. .

  If the temperature of refrigerant container 5 is included in the two-phase separation region (YES in S12), it is estimated that oil is separated from the liquid refrigerant and is present in the upper layer of the liquid refrigerant in refrigerant container 5; The apparatus 100 moves the process to S13.

  In S <b> 13, based on the temperature detected by temperature sensor 102, control device 100 has oil at a specified position in refrigerant container 5 (a position higher than lower end 8 a of bypass flow path 8 by a predetermined amount α). Determine whether or not. For example, when the temperature detected by the temperature sensor 102 is not a value corresponding to a gas refrigerant or a value corresponding to a liquid refrigerant but a value corresponding to lubricating oil, the control device 100 determines that oil is present at a specified position. judge.

  If oil is present at the specified position (YES in S13), control device 100 opens third decompression device 9 in S14. Thereby, in the refrigerant container 5, the oil separated from the liquid refrigerant and staying in the upper part of the liquid refrigerant is returned to the compressor 1 through the bypass channel 8.

  If oil is not present at the specified position (NO at S13), control device 100 determines whether liquid refrigerant is present at the specified position at S15. For example, when the temperature detected by the temperature sensor 102 is not a value corresponding to a gas refrigerant or a value corresponding to oil but a value corresponding to a liquid refrigerant, the control device 100 determines that the liquid refrigerant exists at a specified position. judge.

  If liquid refrigerant is present at the specified position (YES in S15), control device 100 closes third decompression device 9 in S15. Thereby, the liquid refrigerant in the refrigerant container 5 is prevented from returning to the compressor 1 through the bypass channel 8.

  When the liquid refrigerant does not exist at the specified position (NO in S15), control device 100 ends the process.

  FIG. 5 is a diagram illustrating the flow of the refrigerant during the heating operation. During the heating operation, the four-way valve 2 is in a heating cycle state and the compressor 1 is operated. Thereby, the refrigerant discharged from the compressor 1 together with the oil, the four-way valve 2, the second heat exchanger 7, the second decompression device 6, the refrigerant container 5, the first decompression device 4, the first heat exchanger 3, It circulates in the order of the four-way valve 2 and then returns to the compressor 1.

  Specifically, when the compressor 1 is operated, the low-pressure gas refrigerant in the refrigeration cycle is sucked into the compressor 1 from the suction flow path 22 and is discharged after being compressed by the compressor 1 until it reaches a high pressure in the refrigeration cycle. It is discharged into the flow path 23. The high-pressure gas refrigerant discharged from the compressor 1 is sent to the second heat exchanger 7 through the four-way valve 2. The high-pressure gas refrigerant sent to the second heat exchanger 7 exchanges heat with indoor air, dissipates heat, condenses, and becomes high-pressure liquid refrigerant. Thereby, indoor air is heated and indoor heating is performed.

  The high-pressure liquid refrigerant radiated by the second heat exchanger 7 is sent to the second decompression device 6. The high-pressure liquid refrigerant sent to the second decompression device 6 is decompressed by the second decompression device 6 to an intermediate pressure in the refrigeration cycle. The intermediate-pressure refrigerant decompressed by the second decompression device 6 is sent to the refrigerant container 5 and separated into a gas refrigerant and a liquid refrigerant (mixed liquid). The liquid refrigerant separated from the gas refrigerant in the refrigerant container 5 is sent to the first decompression device 4. The intermediate-pressure liquid refrigerant sent to the first decompression device 4 is decompressed by the first decompression device 4 to a low pressure in the refrigeration cycle. The low-pressure liquid refrigerant decompressed by the first decompression device 4 is sent to the first heat exchanger 3.

  The low-pressure liquid refrigerant sent to the first heat exchanger 3 evaporates by exchanging heat with outdoor air in the first heat exchanger 3 to become a low-pressure gas refrigerant. The low-pressure gas refrigerant evaporated in the first heat exchanger 3 is sent to the suction passage 22 through the four-way valve 2 and is sucked into the compressor 1 again.

  During the heating operation as described above, when the temperature of the refrigerant container 5 is equal to or lower than the two-phase separation temperature, the oil is separated from the liquid refrigerant and stays in the upper part of the liquid refrigerant in the refrigerant container 5. As a result, an oil level is formed between the gas refrigerant and the oil, and a liquid level is formed between the oil and the liquid refrigerant.

  When the oil level rises to a specified position in the refrigerant container 5 (a position higher by a predetermined amount α than the lower end 8a of the bypass flow path 8), the third decompression device 9 is opened. Thereby, the oil staying in the upper part of the liquid refrigerant can be returned from the bypass channel 8 to the compressor 1. Furthermore, when the liquid level rises from the specified position, the third decompression device 9 is closed. Thereby, the liquid refrigerant is prevented from returning from the bypass flow path 8 to the compressor 1.

<< Defrost operation and refrigerant recovery operation >>
During the heating operation, when the liquid refrigerant evaporates in the first heat exchanger 3, the temperature of the first heat exchanger 3 decreases, so that frost may adhere to the first heat exchanger 3. is there. Therefore, when the frost adheres to the first heat exchanger 3 during the heating operation, the control device 100 temporarily switches the four-way valve 2 from the heating cycle state to the cooling cycle state in order to remove the frost. Operation (hereinafter referred to as “defrost operation”).

  When the defrosting by the defrost operation is completed, the control device 100 performs an operation (hereinafter referred to as “refrigerant recovery operation”) for recovering the liquid refrigerant accumulated in the first heat exchanger 3 in the refrigerant container 5. During the refrigerant recovery operation, the control device 100 opens the third decompression device 9 and closes the second decompression device 6 while maintaining the four-way valve 2 in the cooling cycle state.

  Then, after the refrigerant recovery operation is completed, the control device 100 returns the four-way valve 2 to the heating cycle state and returns to the heating operation.

  FIG. 6 is a flowchart showing a processing procedure when the control device 100 performs the defrost operation and the refrigerant recovery operation. This flowchart is repeatedly executed at predetermined intervals during the heating operation.

  In S20, control device 100 determines whether or not frost is attached to first heat exchanger 3. For example, the control device 100 determines that frost is attached to the first heat exchanger 3 when the temperature detected by the temperature sensor 101 (liquid pipe temperature of the first heat exchanger 3) is lower than the threshold temperature. To do.

  When frost does not adhere to first heat exchanger 3 (NO in S20), control device 100 ends the process and continues the heating operation.

  When frost has adhered to first heat exchanger 3 (YES in S20), in S21, control device 100 switches destructuring operation by switching four-way valve 2 from the heating cycle state to the cooling cycle state.

  In S22, control device 100 determines whether or not the defrosting by the defrost operation is completed. For example, the control device 100 determines that the defrosting by the defrost operation is completed when the temperature detected by the temperature sensor 101 (the liquid pipe temperature of the first heat exchanger 3) is equal to or higher than a threshold value.

  When defrosting by the defrost operation is not completed (NO in S22), control device 100 returns the process to S21 and continues the defrost operation.

  When defrosting by the defrost operation is completed (YES in S22), control device 100 performs a refrigerant recovery operation. Specifically, the control device 100 opens the third decompression device 9 and closes the second decompression device 6 while maintaining the four-way valve 2 in the cooling cycle state. Thereby, the liquid refrigerant accumulated in the first heat exchanger 3 starts to be collected in the refrigerant container 5.

  In S24, control device 100 determines whether or not the level of the liquid refrigerant in refrigerant container 5 has reached a specified position (a position higher by a predetermined amount α than lower end 8a of bypass flow path 8). For example, when the temperature detected by the temperature sensor 102 changes from a value corresponding to the gas refrigerant or oil to a value corresponding to the liquid refrigerant, the control device 100 determines that the liquid level of the liquid refrigerant has reached the specified position.

  If the liquid level of the liquid refrigerant has not reached the specified position (NO in S24), control device 100 returns the process to S23 and continues the refrigerant recovery operation.

  If the liquid level of the liquid refrigerant has reached the specified position (YES in S24), control device 100 ends the refrigerant recovery operation and returns to the heating operation in S25. Specifically, the control device 100 opens the second decompression device 6, closes the third decompression device 9, and switches the four-way valve 2 from the cooling cycle state to the heating cycle state. Thereby, it returns to heating operation.

  FIG. 7 is a diagram illustrating the flow of the refrigerant during the defrost operation. During the defrost operation, the four-way valve 2 is switched to the cooling cycle state. Thereby, the refrigerant discharged from the compressor 1 together with the oil, the four-way valve 2, the first heat exchanger 3, the first decompression device 4, the refrigerant container 5, the second decompression device 6, the second heat exchanger 7, It circulates in the order of the four-way valve 2 and then returns to the compressor 1.

  Specifically, when the compressor 1 is operated, the low-pressure gas refrigerant in the refrigeration cycle is sucked into the compressor 1 from the suction flow path 22 and is discharged after being compressed by the compressor 1 until it reaches a high pressure in the refrigeration cycle. It is discharged into the flow path 23. The high-pressure gas refrigerant discharged from the compressor 1 is sent to the first heat exchanger 3 through the four-way valve 2. The high-pressure gas refrigerant sent to the first heat exchanger 3 exchanges heat with outdoor air, dissipates heat, condenses, and becomes high-pressure liquid refrigerant. At this time, since the first heat exchanger 3 is heated, frost adhering to the first heat exchanger 3 is removed.

  The high-pressure liquid refrigerant radiated by the first heat exchanger 3 is sent to the first decompression device 4. The high-pressure liquid refrigerant sent to the first decompression device 4 is decompressed by the first decompression device 4 to an intermediate pressure in the refrigeration cycle. The intermediate pressure refrigerant decompressed by the first decompression device 4 is sent to the refrigerant container 5 and separated into a gas refrigerant and a liquid refrigerant (mixed liquid). The liquid refrigerant separated from the gas refrigerant in the refrigerant container 5 is sent to the second decompression device 6. The intermediate-pressure liquid refrigerant sent to the second decompression device 6 is decompressed by the second decompression device 6 to a low pressure in the refrigeration cycle. The low-pressure liquid refrigerant decompressed by the second decompression device 6 is sent to the second heat exchanger 7.

  The low-pressure liquid refrigerant sent to the second heat exchanger 7 evaporates by exchanging heat with indoor air in the second heat exchanger 7 to become a low-pressure gas refrigerant. The low-pressure gas refrigerant evaporated in the second heat exchanger 7 is sent to the suction flow path 22 through the four-way valve 2 and again sucked into the compressor 1.

  FIG. 8 is a diagram illustrating the flow of the refrigerant during the refrigerant recovery operation. During the refrigerant recovery operation, the second pressure reducing device 6 is closed and the third pressure reducing device 9 is opened while the four-way valve 2 is maintained in the cooling cycle state. Thereby, the refrigerant discharged from the compressor 1 circulates along with the oil in the order of the four-way valve 2, the first heat exchanger 3, the first pressure reducing device 4, the refrigerant container 5, and the bypass flow path 8, and then the compressor Returned to 1.

  Therefore, the refrigerant condensed in the first heat exchanger 3 by the defrost operation is sent to the first decompression device 4. The high-pressure liquid refrigerant sent to the first decompression device 4 is decompressed by the first decompression device 4 to an intermediate pressure in the refrigeration cycle. The refrigerant in the intermediate pressure state (the state in which the gas refrigerant and the liquid refrigerant exist) decompressed by the first decompression device 4 is sent to the refrigerant container 5 and separated into the gas refrigerant and the liquid refrigerant. Of the refrigerant sent to the refrigerant container 5, the gas medium flows into the bypass flow path 8 and returns to the compressor 1, but the liquid refrigerant stays in the refrigerant container 5. That is, the liquid refrigerant accumulated in the first heat exchanger 3 during the defrost operation is recovered in the refrigerant container 5 by the refrigerant recovery operation. Thereby, since the quantity of the liquid refrigerant in the 1st heat exchanger 3 decreases, the liquid back phenomenon at the time of returning to heating operation is controlled.

  When the liquid level of the refrigerant liquid in the refrigerant container 5 rises by the refrigerant recovery operation and reaches the lower end 8 a of the bypass flow path 8, the liquid refrigerant flows into the bypass flow path 8 and is returned to the compressor 1. During the refrigerant recovery operation, the second decompression device 6 is closed, and the refrigerant does not flow through the second decompression device 6 and the second heat exchanger 7 and is temporarily switched to a shorter refrigerant circuit than during the defrost operation. It will be. Due to this influence, the oil concentration in the liquid refrigerant in the refrigerant container 5 becomes higher than that during the defrost operation. Therefore, the liquid refrigerant having a high oil concentration flows into the bypass flow path 8 and returns to the compressor 1. As a result, the amount of oil returned to the compressor 1 can be increased.

  Thereafter, when the liquid level of the refrigerant liquid in the refrigerant container 5 reaches a specified position (a position higher than the lower end 8a of the bypass flow path 8 by a predetermined amount α), the third decompression device 9 is closed and the second decompression device 6 is closed. Is opened and returned to heating operation.

  As described above, in the refrigeration cycle apparatus 200 according to the present embodiment, when the defrost operation is completed, the refrigerant recovery operation is performed before returning to the heating operation. During the refrigerant recovery operation, the third pressure reducing device 9 is opened and the second pressure reducing device 6 is closed while the four-way valve 2 is maintained in the cooling cycle state. Thereby, the refrigerant discharged from the compressor 1 flows in the order of the four-way valve 2, the first heat exchanger 3, the first pressure reducing device 4, the refrigerant container 5, and the bypass flow path 8 and is returned to the compressor 1. At this time, the liquid refrigerant accumulated in the first heat exchanger 3 during the defrosting operation is decompressed by the first decompression device 4 and then sent to the refrigerant container 5. Of the refrigerant sent to the refrigerant container 5, the gas medium flows into the bypass flow path 8 and returns to the compressor 1, but the liquid refrigerant stays in the refrigerant container 5. That is, the liquid refrigerant collected in the first heat exchanger 3 is recovered in the refrigerant container 5 by the refrigerant recovery operation. As a result, the amount of liquid refrigerant in the first heat exchanger 3 decreases, so that a liquid back phenomenon (a large amount of liquid refrigerant from the first heat exchanger 3 to the compressor 1 occurs when returning from the defrost operation to the heating operation). Sent phenomenon) is suppressed.

  Furthermore, since the second decompression device 6 is closed during the refrigerant recovery operation, the refrigerant does not flow through the second decompression device 6 and the second heat exchanger 7, and is temporarily switched to a shorter refrigerant circuit than during the defrost operation. Will be. Thereby, the oil concentration in the liquid refrigerant in the refrigerant container 5 becomes higher than that during the defrost operation. Therefore, a liquid refrigerant (mixed liquid) with a high oil concentration can be returned from the bypass flow path 8 to the compressor 1. As a result, the amount of oil returned to the compressor 1 can be increased. As a result, poor lubrication (oil depletion) of the compressor 1 can be suppressed.

  Furthermore, during the heating operation, when the temperature of the refrigerant container 5 (detected temperature of the temperature sensor 102) is equal to or lower than the two-phase separation temperature and the oil level in the refrigerant container 5 reaches the specified position, the third decompression device 9 Is opened. Thereby, even if oil and a liquid refrigerant isolate | separate in the refrigerant | coolant container 5 during heating operation, the oil which stays in an upper layer rather than a liquid refrigerant can be returned to the compressor 1 from the bypass flow path 8. Thereby, the oil return amount of the compressor 1 can be increased during heating operation. As a result, poor lubrication (oil depletion) of the compressor 1 can be suppressed.

<Modification of Embodiment 1>
In the first embodiment described above, when it is determined that the liquid level in the refrigerant container 5 has reached the specified position based on the temperature detected by the temperature sensor 102, the refrigerant recovery operation is stopped and the heating operation is performed. It was returning.

  However, when it is determined that the liquid refrigerant is returned from the refrigerant container 5 to the compressor 1 based on the temperature detected by the temperature sensor 103 (see FIG. 9 described later) provided in the discharge flow path 23, the refrigerant recovery operation is performed. You may make it stop. Even in this case, since the liquid refrigerant (mixed liquid) having a high oil concentration in the refrigerant container 5 can be returned to the compressor before returning to the heating operation, the amount of oil returned to the compressor 1 is temporarily reduced. Can be increased. As a result, poor lubrication (oil depletion) of the compressor 1 can be suppressed.

  FIG. 9 is an overall configuration diagram of a refrigeration cycle apparatus 200A according to this modification. The refrigeration cycle apparatus 200A is obtained by adding a temperature sensor 103 to the refrigeration cycle apparatus 200 shown in FIG. Since the other structure is the same as that of refrigeration cycle apparatus 200 shown in FIG. 1, detailed description thereof will not be repeated here.

  The temperature sensor 103 is disposed in the discharge flow path 23, detects the temperature of the refrigerant discharged from the compressor 1 to the discharge flow path 23 (hereinafter referred to as “discharge temperature”), and outputs the detection result to the control device 100.

  FIG. 10 is a flowchart showing a processing procedure when the control device 100 according to the present modification performs the defrost operation and the refrigerant recovery operation. Note that the flowchart shown in FIG. 10 is obtained by changing S24 in the flowchart shown in FIG. 6 to S24A. Since other steps are the same as those in the flowchart shown in FIG. 6, detailed description thereof will not be repeated here.

  In S24A, control device 100 determines whether or not the discharge temperature detected by temperature sensor 103 is lower than the target discharge temperature. This determination is a process for determining whether or not the liquid refrigerant in the refrigerant container 5 is actually returned to the compressor 1. That is, since the target discharge temperature is a temperature that assumes that the compressor 1 is compressing the gas refrigerant, the discharge temperature is lower than the target discharge temperature when the compressor 1 is compressing the liquid refrigerant. Become.

  When the discharge temperature detected by temperature sensor 103 is not lower than the target discharge temperature (NO in S24A), control device 100 returns the process to S23 and continues the refrigerant recovery operation.

  On the other hand, when the discharge temperature detected by temperature sensor 103 is lower than the target discharge temperature (YES in S24A), that is, it is detected that the liquid refrigerant in refrigerant container 5 is actually returned to compressor 1. In this case, the control device 100 moves the process to S25, stops the refrigerant recovery operation, and returns to the heating operation.

  Even in this case, since the liquid refrigerant (mixed liquid) having a high oil concentration in the refrigerant container 5 can be returned to the compressor before returning to the heating operation, the amount of oil returned to the compressor 1 is temporarily reduced. Can be increased. As a result, poor lubrication (oil depletion) of the compressor 1 can be suppressed.

  In this modification, it is indirectly determined using the temperature sensor 103 that detects the discharge temperature that the liquid level in the refrigerant container 5 exceeds the lower end 8a of the bypass flow path 8. It will also be a thing. Therefore, the temperature sensor 102 arranged on the side surface of the refrigerant container 5 can be omitted.

[Embodiment 2]
In Embodiment 1 described above, it has not been assumed that the liquid refrigerant and oil in the refrigerant container 5 are positively separated during the refrigerant recovery operation.

  On the other hand, in the second embodiment, the liquid refrigerant and the oil in the refrigerant container 5 are actively separated during the refrigerant recovery operation so that the oil staying above the liquid refrigerant is removed from the bypass flow path 8. Is actively collected by the compressor 1. Since other structures, functions, and processes are the same as those in the first embodiment, detailed description thereof will not be repeated here.

  FIG. 11 is a flowchart showing a processing procedure when control device 100 according to the present embodiment performs the defrost operation and the refrigerant recovery operation. Of the steps shown in FIG. 11, the steps given the same numbers as the steps shown in FIG. 6 have already been described, and detailed description thereof will not be repeated here.

  In S30, control device 100 reduces the opening of first decompression device 4 by a predetermined amount so that the temperature of refrigerant container 5 is equal to or lower than the two-phase separation temperature (see FIG. 3) during the refrigerant recovery operation.

  In S31, control device 100 determines whether or not the temperature of refrigerant container 5 detected by temperature sensor 102 is equal to or lower than the two-phase separation temperature. If the temperature of refrigerant container 5 is not equal to or lower than the two-phase separation temperature (NO in S31), control device 100 returns the process to S23.

  When the temperature of refrigerant container 5 is equal to or lower than the two-phase separation temperature (YES in S31), since it is assumed that the oil is separated from the liquid refrigerant, control device 100 moves the process to S32.

  In S32, control device 100 determines whether or not there is a history that the oil level in refrigerant container 5 has reached the specified position during the current refrigerant recovery operation. For example, if there is a history in which the temperature detected by the temperature sensor 102 has changed from a value corresponding to a gas refrigerant to a value corresponding to oil during the current refrigerant recovery operation, It is determined that there is a history that the surface has reached the specified position.

  If there is no history that the oil level has reached the specified position (NO in S32), control device 100 returns the process to S23.

  If there is a history that the oil level has reached the specified position (YES in S32), in S33, control device 100 determines whether or not the liquid level of the liquid refrigerant in refrigerant container 5 has reached the specified position. . For example, the control device 100 determines that the liquid level has reached the specified position when the temperature detected by the temperature sensor 102 changes from a value corresponding to oil to a value corresponding to liquid refrigerant.

  If the liquid level has not reached the specified position (NO in S33), control device 100 returns the process to S23. If the liquid level has reached the specified position (YES in S33), control device 100 moves the process to S25, stops the refrigerant recovery operation, and returns to the heating operation.

  FIG. 12 is a diagram showing a refrigerant flow and an oil flow in the refrigerant container 5 in the present embodiment. In the present embodiment, the opening degree of the first decompression device 4 is reduced so that the temperature of the refrigerant container 5 is equal to or lower than the two-phase separation temperature. Thereby, when the temperature of the refrigerant container 5 is actually equal to or lower than the two-phase separation temperature, the refrigerant container 5 is separated into two phases of liquid refrigerant and oil, the liquid refrigerant stays in the lower part in the refrigerant container, and the oil It stays on the liquid refrigerant. Therefore, the liquid level of the liquid refrigerant is formed between the oil and the liquid refrigerant, and the oil level is formed between the gas refrigerant and the oil. By the refrigerant recovery operation, the oil level and the liquid level in the refrigerant container 5 are increased. When the oil level height exceeds the specified position, the oil flows into the bypass flow path 8 and is collected by the compressor 1. Thereby, since the amount of oil return to the compressor 1 is increased, poor lubrication of the compressor 1 is suppressed.

  Thereafter, when the liquid level reaches the specified position, the third decompression device 9 is closed and the refrigerant recovery operation is stopped. Therefore, the liquid refrigerant is prevented from returning to the compressor 1 through the bypass flow path 8.

  Thus, in the present embodiment, while the refrigerant liquid and the oil in the refrigerant container 5 are actively separated during the refrigerant recovery operation, the liquid refrigerant staying in the lower part is retained in the refrigerant container 5. The oil staying in the upper part of the liquid refrigerant can be returned from the bypass flow path 8 to the compressor 1. Thereby, the oil return amount to the compressor 1 can be increased while suppressing the liquid back phenomenon when returning from the defrost operation to the heating operation.

[Embodiment 3]
In the bypass channel 8 according to the above-described first and second embodiments, the refrigerant container 5 has only one opening (refrigerant and oil inlet) at the lower end 8a. Therefore, the gas refrigerant and oil cannot be sent to the bypass flow path 8 at the same time.

  On the other hand, in the bypass flow path 80 (see FIG. 13 described later) according to the third embodiment, two openings (an oil inlet and a gas refrigerant inlet) are provided inside the refrigerant container 5. . Since other structures, functions, and processes are the same as those in the first embodiment, detailed description thereof will not be repeated here.

  FIG. 13 is a diagram schematically showing the internal structure of the refrigerant container 5A according to the present embodiment. As shown in FIG. 13, the bypass flow path 80 according to the third embodiment is formed in a U-shape inside the refrigerant container 5, and an oil inflow port 80 a is provided at the lowermost portion, and at the end. An inflow port 80b for gas refrigerant is provided. Therefore, the gas refrigerant inflow port 80b is disposed upstream of the oil inflow port 80a and higher than the oil inflow port 80a.

  When the temperature of the refrigerant container 5 becomes equal to or lower than the two-phase separation temperature during the refrigerant recovery operation, the oil is separated from the liquid refrigerant in the refrigerant container 5, and the oil stays in the upper part of the liquid refrigerant. When the oil level height exceeds the oil inlet 80a, the oil flows into the inlet 80a. At the same time, the gas refrigerant staying in the upper part of the oil flows into the inflow port 80b, merges with the oil that flows in from the inflow port 80a, and is returned to the compressor 1. Since the gas refrigerant flows at a higher speed than the oil, it is dragged by the flow of the gas refrigerant and the oil flow rate is also increased. Further, the oil level can be further raised by the gas refrigerant in the refrigerant container 5 being removed. Therefore, the time required to return the oil staying in the refrigerant container 5 to the compressor 1 can be shortened.

  As described above, in this modified example, the inlet 80a for oil and the inlet 80b for gas refrigerant are provided in the portion provided in the refrigerant container 5 in the bypass flow path 80. The gas refrigerant inflow port 80b is disposed upstream of the oil inflow port 80a and higher than the oil inflow port 80a. Thereby, since the gas refrigerant can be caused to flow from the upstream side of the oil at the same time as the oil is caused to flow into the bypass flow path 8, the flow rate of the oil can be increased. As a result, the time required to return the oil staying in the refrigerant container 5 to the compressor 1 can be shortened.

  The positions of the oil inlet 80a (first opening) and the gas refrigerant inlet 80b (second opening) are not necessarily limited to the positions shown in FIG. That is, the inflow port for gas refrigerant (second opening) is upstream of the inflow port for oil (first opening) in the refrigerant flow direction, and the inflow port for oil (first opening). As long as it is positioned higher than.

  The above-described embodiments and modifications can be combined as appropriate within a range where no technical contradiction arises.

  The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

DESCRIPTION OF SYMBOLS 1 Compressor, 2 Four way valve, 3 1st heat exchanger, 4 1st pressure reduction device, 5, 5A Refrigerant container, 5a bottom surface, 5b upper surface, 6 2nd pressure reduction device, 7 2nd heat exchanger, 8, 80 bypass Flow path, 8a, 25a, 26a Lower end, 9 Third decompression device, 10 Junction section, 22 Suction flow path, 23 Discharge flow path, 24, 25, 26, 27 Refrigerant flow path, 80a, 80b Inlet, 100 Control device 101, 102, 103 Temperature sensor, 200, 200A Refrigeration cycle apparatus.

Claims (3)

A refrigeration cycle device in which lubricating oil circulates with a refrigerant,
A compressor provided between the suction flow path and the discharge flow path;
A first heat exchanger for exchanging heat between air and refrigerant;
A second heat exchanger for exchanging heat between the air and the refrigerant;
A refrigerant container provided on a refrigerant flow path connecting the first heat exchanger and the second heat exchanger;
A first pressure reducing device provided on a refrigerant flow path connecting the first heat exchanger and the refrigerant container;
A second pressure reducing device provided on a refrigerant flow path connecting the second heat exchanger and the refrigerant container;
A cooling cycle state in which the suction flow path is connected to the second heat exchanger and the discharge flow path is connected to the first heat exchanger; the suction flow path is connected to the first heat exchanger; and A switching device configured to be switchable to any state of a heating cycle state in which a discharge channel is connected to the second heat exchanger;
A bypass passage connecting the inside of the refrigerant container and the suction passage;
A third pressure reducing device provided on the bypass flow path;
A control device for switching to a defrost operation for setting the switching device to the cooling cycle state during a heating operation for operating the compressor with the switching device in the heating cycle state,
When the defrost operation is completed, the control device performs a refrigerant recovery operation that opens the third pressure reduction device and closes the second pressure reduction device while maintaining the switching device in the cooling cycle state, and performs the refrigerant recovery operation. After completion, return the switching device to the heating cycle state and return to the heating operation,
Said controller, in the refrigerant recovery during operation, liquid refrigerant and lubricating oil temperature of the refrigerant vessel inside the refrigerant container is such that the temperature at which the separation, for controlling the first pressure reducing device, refrigeration cycles apparatus. A refrigeration cycle device in which lubricating oil circulates with a refrigerant,
A compressor provided between the suction flow path and the discharge flow path;
A first heat exchanger for exchanging heat between air and refrigerant;
A second heat exchanger for exchanging heat between the air and the refrigerant;
A refrigerant container provided on a refrigerant flow path connecting the first heat exchanger and the second heat exchanger;
A first pressure reducing device provided on a refrigerant flow path connecting the first heat exchanger and the refrigerant container;
A second pressure reducing device provided on a refrigerant flow path connecting the second heat exchanger and the refrigerant container;
A cooling cycle state in which the suction flow path is connected to the second heat exchanger and the discharge flow path is connected to the first heat exchanger; the suction flow path is connected to the first heat exchanger; and A switching device configured to be switchable to any state of a heating cycle state in which a discharge channel is connected to the second heat exchanger;
A bypass passage connecting the inside of the refrigerant container and the suction passage;
A third pressure reducing device provided on the bypass flow path;
A control device for switching to a defrost operation for setting the switching device to the cooling cycle state during a heating operation for operating the compressor with the switching device in the heating cycle state,
When the defrost operation is completed, the control device performs a refrigerant recovery operation that opens the third pressure reduction device and closes the second pressure reduction device while maintaining the switching device in the cooling cycle state, and performs the refrigerant recovery operation. After completion, return the switching device to the heating cycle state and return to the heating operation,
In the heating operation, the control device is configured such that the refrigerant temperature in the refrigerant container is a temperature at which the liquid refrigerant and the lubricating oil are separated, and the lubricating oil surface in the refrigerant container reaches the lower end of the bypass flow path. opening said third decompressor, refrigeration cycle apparatus. A refrigeration cycle device in which lubricating oil circulates with a refrigerant,
A compressor provided between the suction flow path and the discharge flow path;
A first heat exchanger for exchanging heat between air and refrigerant;
A second heat exchanger for exchanging heat between the air and the refrigerant;
A refrigerant container provided on a refrigerant flow path connecting the first heat exchanger and the second heat exchanger;
A first pressure reducing device provided on a refrigerant flow path connecting the first heat exchanger and the refrigerant container;
A second pressure reducing device provided on a refrigerant flow path connecting the second heat exchanger and the refrigerant container;
A cooling cycle state in which the suction flow path is connected to the second heat exchanger and the discharge flow path is connected to the first heat exchanger; the suction flow path is connected to the first heat exchanger; and A switching device configured to be switchable to any state of a heating cycle state in which a discharge channel is connected to the second heat exchanger;
A bypass passage connecting the inside of the refrigerant container and the suction passage;
A third pressure reducing device provided on the bypass flow path;
A control device for switching to a defrost operation for setting the switching device to the cooling cycle state during a heating operation for operating the compressor with the switching device in the heating cycle state,
When the defrost operation is completed, the control device performs a refrigerant recovery operation that opens the third pressure reduction device and closes the second pressure reduction device while maintaining the switching device in the cooling cycle state, and performs the refrigerant recovery operation. After completion, return the switching device to the heating cycle state and return to the heating operation,
A portion provided in the refrigerant container in the bypass flow path is provided with a first opening and a second opening,
The second opening is an upstream side of the first refrigerant flow direction than the opening, and is arranged at a position higher than the first opening, refrigeration cycle apparatus.

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