ES2964488T3 - Outdoor unit and refrigeration cycle device - Google Patents

Abstract

An outdoor unit (2) is provided with: a first flow channel (F1); a second flow channel (F2); a second expansion device (71), a liquid receiver (73) and a flow regulating valve (72) positioned in the second flow channel (F2) in order from a branch point; a heat exchanger (30); and a control device (100). The heat exchanger (30) exchanges heat between a refrigerant flowing through a first pass (H1) and a refrigerant flowing through a second pass (H2). If a pumping operation is started to recover refrigerant to the liquid receiver (73), the control device (100): controls, at first, a control state of a compressor (10) and the flow regulating valve ( 72) to a first state in which the flow regulating valve (72) is closed while the compressor (10) is operating; and transitions, at a second moment of the pumping operation subsequent to the first moment, the control state of the first state to a second state in which the flow regulating valve (72) opens while the compressor (10) is operated. (Automatic translation with Google Translate, without legal value)

Description

DESCRIPTION

Outdoor unit and refrigeration cycle device

Technical field

The present disclosure relates to an outdoor unit and a refrigeration cycle apparatus.

Previous technique

Japanese Patent Laid-Open No. 2014-01917 (PTL 1) discloses a refrigeration apparatus having an intermediate injection flow path and a suction injection flow path. In this refrigeration apparatus, a portion of refrigerant flowing from a condenser to an evaporator can be merged with the intermediate pressure refrigerant in a compressor using the intermediate injection flow path, and can also be merged with the low pressure refrigerant. to be sucked into the compressor in a suction flow path using the suction injection flow path. Accordingly, in a case where using the intermediate injection flow path results in a deterioration of the operating efficiency, the suction injection flow path can be used to decrease the discharge temperature of the compressor.

Appointment list

Patent literature

PTL 1: Japanese Patent Laid-Open No. 2014-01917

Summary of the invention

technical problem

A pump dump operation is an operation to transfer refrigerant from a charging device to an outdoor unit and store the refrigerant therein by placing a shut-off valve or similar in a pipe through which liquid refrigerant flows in a cooling circuit. main refrigerant, and run a compressor with the tube blocked.

In the refrigeration apparatus described in Japanese Patent Laid-Open No. 2014-01917 (PTL 1), when, for example, the operation of a charging device is stopped, thereby blocking circulation of the refrigerant on the indoor unit side and a pump drain operation to be performed on the charging device side is started, the refrigerant in the charging device is recovered in the outdoor unit. On this occasion, if refrigerant recovery continues and the refrigerant in a high-pressure part decreases, the condensing temperature approaches the outside air temperature and the refrigerant becomes less liquefied in the condenser. Consequently, time is required to recover the coolant, resulting in increased time for the pump-out operation.

US 2015/338121 describes an air conditioning apparatus including: a first bypass tube connected to a channel on the inlet side of an accumulator through a second expansion device, a second channel of a subcooling heat exchanger for exchanging heat between the refrigerant flowing through the second channel of the subcooling heat exchanger and the refrigerant flowing through a first channel of the subcooling heat exchanger, and a first opening and closing device; a second branch pipe branched from the first branch pipe between the subcooling heat exchanger and the first opening and closing device and connected to an injection port of a compressor through a second opening and closing device; and a third branch pipe branched from a refrigerant pipe between a heat source side heat exchanger and a use side heat exchanger and connected to a refrigerant pipe between an inlet side of the compressor and a side accumulator outlet through a third expansion device.

WO 2008/130357 describes a refrigerant vapor compression system that includes an expansion tank economizer that defines a separation chamber that is arranged in the refrigerant circuit between a refrigerant heat rejection heat exchanger and a refrigerant heat absorption heat exchanger.

Document JP 2009-156531 A discloses an outdoor unit according to the preamble of claim 1.

An object of the present invention is to provide an outdoor unit and refrigeration cycle apparatus with a reduced refrigerant recovery time during a pump dump operation.

Solution to the problem

The present invention is defined by the attached claims. This disclosure refers to a

outdoor unit of a refrigeration cycle device, the outdoor unit being able to connect to a refrigeration device

charge that includes a first expansion device and an evaporator. The outdoor unit includes: a first way

flow path configured to form a circulation flow path through which refrigerant circulates, when connected

to the charging device; a compressor and a condenser arranged in the first flow path; a second way of

flow configured to branch from a branch point in the first flow path downstream of the condenser in a direction in which the refrigerant circulates, and to return, to the compressor, the refrigerant that

has passed through the condenser; a second expansion device, a receiver and a control valve

of flow arranged in the second flow path in order from the branch point; and an exchanger

heat having a first channel and a second channel and configured to exchange heat between the refrigerant that

flows in the first channel and the refrigerant flows in the second channel. The first channel of the heat exchanger

It is arranged between the condenser and the branch point in the first flow channel. The second channel of the heat exchanger is arranged between the flow control valve and the compressor in the second channel

flow. The flow control valve is configured to adjust the expulsion flow rate of liquid refrigerant

from the receiver. When a pump drain operation is initiated to recover the coolant in the

receiver, a control state of the compressor and the flow control valve is established, at a first point

of time, in a first state in which the flow control valve is closed while the compressor is

working. During the pump emptying operation, at a second time point after the

first time point, the control state transitions from the first state to a second state in which the control valve

Flow control is open while the compressor is running.

Advantageous effects of the invention

According to the outdoor unit of the present invention, even when refrigerant recovery continues

and the condensation temperature approaches the outside air temperature during a drain operation

With a pump, the refrigerant is condensed, maintaining the efficiency of the heat exchanger. This can reduce

the time required for refrigerant recovery.

Brief description of the drawings

The fig. 1 is an overall configuration diagram of a refrigeration cycle apparatus according to the

present embodiment.

The fig. 2 is a flow diagram to illustrate the control of a second expansion valve 71.

The fig. 3 is a flow diagram to illustrate the control of a flow control valve 72.

The fig. 4 is a flow diagram to illustrate control during a pump emptying operation.

Description of embodiments

Hereinbelow, embodiments of the present disclosure will be described in detail.

with reference to the drawings. Although a plurality of embodiments will be described below, from

At the time of filing this application, it is originally intended to combine the characteristic features

described in the embodiments as appropriate. It should be noted that identical or corresponding parts in the drawings will be designated with the same reference characters and their description will not be repeated.

The fig. 1 is an overall configuration diagram of a refrigeration cycle apparatus according to the present

mode of realization. It should be noted that fig. 1 functionally shows the connection relationship and configuration

arrangement of devices in the refrigeration cycle apparatus, and does not necessarily show an arrangement

in a physical space.

In reference to fig. 1, a refrigeration cycle apparatus 1 includes an outdoor unit 2, a charging device

3 and pipes 84 and 88. Outdoor unit 2 has a PO2 refrigerant outlet port and a PO2 inlet port.

refrigerant PI2 to connect to charging device 3. Charging device 3 has an outlet hole of

PO3 refrigerant and a PI3 refrigerant inlet port to connect to the outdoor unit 2. Pipe 84

connects the PO2 refrigerant outlet port of the outdoor unit 2 to the PI3 refrigerant inlet port of the charging device 3. Pipe 88 connects the PO3 refrigerant outlet port of the charging device 3 to the

refrigerant inlet port PI2 of outdoor unit 2.

The outdoor unit 2 of the refrigeration cycle appliance 1 can be connected to the charging device 3. The unit

outer 2 includes a compressor 10 having a suction port G1, a discharge port G2 and a discharge port

intermediate pressure G3, a condenser 20, a fan 22, a heat exchanger 30 and tubes from 80 to 82 and

89. The heat exchanger 30 has a first channel H1 and a second channel H2, and is configured to

exchanging heat between the refrigerant flowing in the first channel H1 and the refrigerant flowing in the second channel H2.

The charging device 3 includes a first expansion valve 50, an evaporator 60, tubes 85, 86 and 87 and a shut-off valve 28. The evaporator 60 is configured to perform a heat exchange between the air and the refrigerant. In the refrigeration cycle apparatus 1, the evaporator 60 evaporates the refrigerant by absorbing heat from the air in a space to be cooled. The first expansion valve 50, for example, is a temperature-controlled expansion valve independently of the outdoor unit 2. It should be noted that the first expansion valve 50 may be an electronic expansion valve that can decompress the refrigerant. The shut-off valve 28 closes when the charging device 3 stops operating, to block the refrigerant.

The compressor 10 compresses the refrigerant by sucking from the tube 89 and discharges the compressed refrigerant to the tube 80. The compressor 10 can arbitrarily change a drive frequency by control of the inverter. Furthermore, the compressor 10 is provided with an intermediate pressure port G3 and allows the refrigerant from the intermediate pressure port G3 to flow to an intermediate part of a compression process. The compressor 10 is configured to adjust a rotation speed according to a control signal of a controller 100. By adjusting the rotation speed of the compressor 10, a circulation amount of the refrigerant is adjusted and the capacity of the cycle apparatus can be adjusted. refrigeration 1. As a compressor 10, various types of compressors can be adopted, and for example, a spiral type compressor, a rotary type compressor, a screw type compressor or the like can be adopted.

The condenser 20 is configured so that the high temperature and high pressure gaseous refrigerant discharged from the compressor 10 performs heat exchange with the outside air (heat dissipation). Through this heat exchange, the refrigerant condenses and transforms into a liquid phase. The refrigerant discharged from the compressor 10 to the tube 80 is condensed and liquefied in the condenser 20 and flows to the tube 81. The fan 22 for blowing outside air is coupled to the condenser 20 to increase the efficiency of heat exchange. The fan 22 supplies the condenser 20 with outside air with which the refrigerant carries out heat exchange in the condenser 20. By adjusting the number of revolutions of the fan 22, the pressure of the refrigerant on a discharge side of the compressor 10 can be adjusted ( the pressure on the high pressure side).

Here, it is assumed that the refrigerant used for a refrigerant circuit of the refrigeration cycle apparatus 1 is CO<2>. However, when a state occurs where subcooling is less likely to be guaranteed, another refrigerant can be used.

It should be noted that, herein, for ease of description, a device that cools the refrigerant, such as CO<2>in a supercritical state will also be referred to as condenser 20. Furthermore, herein, for ease of description , an amount of decrease from a reference temperature of the coolant in the supercritical state will also be called subcooling.

A first flow path F1 is formed from the refrigerant inlet port PI2 to the refrigerant outlet port PO2 by means of the compressor 10, the condenser 20 and the first channel H1 of the heat exchanger 30, together with a flow path in which the first expansion valve 50 and the evaporator 60 of the charging device 3 are arranged, a circulation flow path through which the refrigerant circulates. Hereinafter, this circulation flow path will also be referred to as the "main refrigerant circuit" of a refrigeration cycle.

The outdoor unit 2 further includes tubes 91, 92 and 94 configured to cause refrigerant to flow from a part of the circulation flow path between an outlet of the first channel H1 and the refrigerant outlet port PO2 to an inlet of the second channel H2, and the tube 96 configured to cause the refrigerant to flow from an outlet of the second channel H2 to the intermediate pressure port G3 of the compressor 10. Hereinafter, a second flow path F2 branching from the circuit of main refrigerant and supplies the refrigerant to the compressor 10 through the second channel H2 will also be called "injection flow path".

The outdoor unit 2 further includes a receiver 73 disposed in the second flow path F2 and configured to store the refrigerant. A second expansion valve 71 is arranged between the tubes 91 and 92, the tube 91 branches from the part of the circulation flow path between the outlet of the first channel H1 and the refrigerant outlet port PO2, and the tube 92 is connected to an inlet of the receiver 73. The outdoor unit 2 further includes a degassing tube 93 that connects a gas expulsion outlet of the receiver 73 to the second channel H2 and is configured to expel a refrigerant gas into the receiver 73, a shutter device 70 arranged between the degassing tube 93 and the tube 94 that gives rise to the second channel H2, and a flow control valve 72 configured to adjust a flow rate of the refrigerant in the tube 94 connected to a liquid refrigerant expulsion outlet of the receiver 73.

The tube 91 is a tube that branches from the main refrigerant circuit and causes the refrigerant to flow into the receiver 73. The second expansion valve 71 is an electronic expansion valve that can decrease the pressure of the refrigerant by a pressure part of the main refrigerant circuit at an intermediate pressure. The receiver 73 is a container in which the decompressed refrigerant having two phases is separated into a gas phase and a liquid phase, and which can store the refrigerant and adjust the amount of refrigerant circulation in the main refrigerant circuit. The degassing tube 93 connected to an upper part of the receiver 73 and the tube 94 connected to a lower part of the receiver 73 are tubes for taking out the separated refrigerant into gaseous refrigerant and liquid refrigerant inside the receiver 73, in a separate state. The flow control valve 72 adjusts the amount of the liquid refrigerant to be expelled from the tube 94, and thus can adjust the amount of the refrigerant in the receiver 73.

By providing the receiver 73 in the injection flow path as described above, it is easy to ensure subcooling in the tubes 82 and 83, which are liquid tubes. This is because, since the receiver 73 generally includes the gaseous refrigerant therein and the refrigerant temperature reaches the saturation temperature, it is not possible to ensure subcooling if the receiver 73 is arranged in the tube 82.

Furthermore, if the receiver 73 is provided in an intermediate pressure part, it is possible to store the intermediate pressure liquid refrigerant inside the receiver 73 even when the pressure in the high pressure part of the main refrigerant circuit is high and the refrigerant is in the supercritical state. Therefore, the design pressure of the receiver vessel 73 can be set to be lower than that of the high-pressure portion, and cost reduction can also be achieved by decreasing the thickness of the vessel.

The outdoor unit 2 further includes pressure sensors 110 and 111, temperature sensors 120 to 123 and a controller 100 configured to control the compressor 10, the second expansion valve 71 and the flow control valve 72.

The pressure sensor 110 detects a pressure PL in the suction port portion of the compressor 10 and sends a detection value thereof to the controller 100. The pressure sensor 111 detects a discharge pressure PH of the compressor 10 and sends a value detection thereof to controller 100.

The temperature sensor 120 detects the discharge temperature TH of the compressor 10 and sends a detection value thereof to the controller 100. The temperature sensor 121 detects the refrigerant temperature T1 in the tube 81 at an outlet of the condenser 20, and sends a detection value thereof to the controller 100. The temperature sensor 122 detects the coolant temperature T2 at the outlet of the first channel H1 on a cooled side of the heat exchanger 30 and sends a detection value thereof to the controller. 100. The temperature sensor 123 detects the outdoor air temperature TA, which is the ambient temperature of the outdoor unit 2, and sends a detection value thereof to the controller 100.

In the present embodiment, the second flow path F2 controls the discharge temperature TH of the compressor 10 by causing the refrigerant to decompress and causing two phases to flow to the compressor 10. In addition, the amount of the refrigerant in the refrigerant circuit main can be adjusted by the receiver 73 placed in the second flow path F2. In addition, the second flow path F2 also ensures supercooling of the refrigerant in the main refrigerant circuit by heat exchange by the heat exchanger 30.

The controller 100 includes a CPU (central processing unit) 102, a memory 104 (a ROM (read-only memory) and a RAM (random access memory)), input/output buffers (not shown) for input/output send various signals, and the like. The CPU 102 expands the programs stored in the ROM into RAM or the like and executes the programs. The programs stored in the ROM are programs that describe processing procedures of the controller 100. According to these programs, the controller 100 performs control of the devices in the outdoor unit 2. This control can be processed not only by a computer program, but also by specialized computer equipment (electronic circuits).

Control during normal operation

The controller 100 feedback controls the second expansion valve 71 so that the discharge temperature TH of the compressor 10 matches the target temperature.

The fig. 2 is a flow chart to illustrate the control of the second expansion valve 71. When the discharge temperature TH of the compressor 10 is greater than the target temperature (YES in S21), the controller 100 increases the opening degree of the second expansion valve 71 (S22). In this way, the refrigerant flowing to the intermediate pressure orifice G3 through the receiver 73 is increased and, therefore, the discharge temperature TH decreases.

On the other hand, when the discharge temperature TH of the compressor 10 is lower than the target temperature (NO in S21 and YES in S23), the controller 100 decreases the opening degree of the second expansion valve 71 (S24). In this way, the refrigerant flowing to the intermediate pressure orifice G3 through the receiver 73 decreases and, therefore, the discharge temperature<t>H increases.

When the discharge temperature TH is equal to the target temperature (NO in S21 and NO in S23), the controller 100 maintains the opening degree of the second expansion valve 71 in the current state.

Therefore, the controller 100 controls the opening degree of the second expansion valve 71 so that the discharge temperature TH of the compressor 10 approaches the target temperature.

Furthermore, in normal operation, the controller 100 feedback controls the flow control valve 72 so that the refrigerant temperature T1 at the outlet of the condenser 20 matches the target temperature, to ensure SC subcooling of the refrigerant at the outlet. of capacitor 20.

The fig. 3 is a flow chart to illustrate the control of the flow control valve 72. When the subcooling SC determined by the refrigerant temperature T1 at the outlet of the condenser 20 and the pressure in the condenser 20 (approximated by PH) is greater than a target value (YES in S31), the controller 100 decreases one degree of opening of the flow control valve 72 (S32). In this way, the amount of the liquid refrigerant to be expelled from the receiver 73 decreases and the amount of the liquid refrigerant inside the receiver 73 increases and, therefore, the amount of the refrigerant circulating through the main refrigerant circuit decreases. Consequently, the coolant temperature T1 increases and, therefore, the subcooling SC decreases.

On the other hand, when the subcooling SC determined by the refrigerant temperature T1 at the outlet of condenser 20 and the pressure in condenser 20 (approximated by PH) is lower than the target value (NO in S31 and YES in S33), the controller 100 increases the opening degree of the flow control valve 72 (S34). In this way, the amount of the liquid refrigerant to be expelled from the receiver 73 is increased and the amount of the liquid refrigerant stored in the receiver 73 decreases and, therefore, the amount of the refrigerant circulating through the refrigerant circuit is increased. major. Consequently, the coolant temperature T1 decreases and, therefore, the subcooling SC increases.

When the subcooling SC is equal to the target value (NO in S31 and NO in S33), the controller 100 maintains the opening degree of the flow control valve 72 in the current state.

Therefore, the controller 100 controls the opening degree of the flow control valve 72 so that the refrigerant temperature T1 at the outlet of the condenser 20 approaches the target temperature.

Control during pump emptying operation

Furthermore, in normal operation, the controller 100 feedback controls the flow control valve 72 so that the refrigerant temperature T1 at the outlet of the condenser 20 matches the target temperature, to ensure subcooling SC of the refrigerant at the outlet. of the condenser 20, and, in a pump drain operation, the controller 100 closes the flow control valve 72 to recover the liquid refrigerant in the receiver 73.

The pump emptying operation is an operation to transfer the refrigerant from the charging device 3 to the outdoor unit 2 and store the refrigerant therein, by placing the shut-off valve 28 or the like on the pipe 85 through which the refrigerant flows. liquid in the main refrigerant circuit and operate the compressor 10 with the tube 85 blocked. The pump emptying operation is carried out, for example, by closing the first expansion valve 50 or the shut-off valve 28 before stopping the operation, and, after this, operating the compressor 10.

Generally, a signal for instructing to start the pump emptying operation is not transmitted, in particular, from the charging device 3 to the outdoor unit 2, and the pump emptying operation is performed in the outdoor unit 2 continuing. normal operation when the pressure PL in the low pressure part detected by the pressure sensor 110 decreases to a threshold value PA.

In the pump dump operation, when the stop valve 28 is closed and the pressure PL in the low pressure part detected by the pressure sensor 110 decreases to a threshold value PB, the controller 100 is configured to stop the compressor 10 and stop emptying with pump. Since the compressor 10 is configured so that the refrigerant cannot pass through it when it is stopped, the refrigerant does not flow back to the charging device 3.

The fig. 4 is a flow chart to illustrate the control during the pump emptying operation. First, in step S41, the controller 100 determines whether the pressure PL in the low pressure portion detected by the pressure sensor 110 is less than the threshold value PA. When PL < threshold value PA is satisfied (YES in S41), the pump emptying operation is performed in and after step S42. On the other hand, when PL < threshold value PA is not satisfied (NO in S41), the pump emptying operation is not performed and the control is returned to processing in normal operation in step S47.

In step S42, the controller 100 determines whether the refrigerant temperature T1 in the condenser 20 is less than TA+a. Here, a indicates a temperature difference between the refrigerant and the outside air that can cause a significant reduction in the condensation efficiency of the refrigerant in the condenser 20 if the temperature difference is even lower, and is a value determined as appropriate.

When T1 < TA+a (NO in S42) is not satisfied, in step S43, the controller 100 closes the flow control valve 72. Thus, the gaseous refrigerant is expelled from the receiver 73 through the degassing tube. 93, and the liquid refrigerant is recovered in receiver 73.

On the other hand, when T1 < TA+a is satisfied (YES in S42), in step S44, the controller 100 slightly increases the opening degree of the flow control valve 72. In this way, the liquid refrigerant stored in The receiver 73 flows to the second channel H2 of the heat exchanger 30. When the flow control valve 72 is closed, the gaseous refrigerant flows to the second channel H2 of the heat exchanger 30 through the degassing tube 93. In the state in the gaseous refrigerant flows, the heat transfer coefficient between the heat exchanger and the refrigerant in the second H2 channel is low.

Here, if the liquid refrigerant is mixed by slightly opening the flow control valve 72, the heat transfer coefficient between the heat exchanger and the refrigerant in the second channel H2 is improved by 10 times or more. In this way, the refrigerant that has become less condensed is condensed in the condenser 20 in a phase in which the recovery of the liquid refrigerant has continued to a certain extent in the heat exchanger 30 and, therefore, the recovery of the liquid refrigerant can continue. It should be noted that, since the amount of the recovered liquid refrigerant does not increase if the opening degree of the flow control valve 72 is increased too much, the opening degree of the flow control valve 72 in step S44 is set so that it falls within an interval in which the amount of liquid refrigerant recovered in the receiver 73 increases.

Preferably, furthermore, in step S45, the controller 100 increases the rotation speed of the compressor 10, although the controller 100 does not necessarily have to perform this step. This can reduce the time to recover the remaining refrigerant that has become less condensed because recovery has continued.

Subsequently, in step S46, the controller 100 determines whether the pressure PL in the low pressure portion detected by the pressure sensor 110 decreases to the threshold value PB. The threshold value p B is a value smaller than the threshold value PA, and is a determination value to determine that the refrigerant recovery in the charging device 3 is completed. As long as the pressure PL does not decrease to the threshold value PB (NO at S46), the controller 100 continues the operation of the compressor 10 and continues the pump emptying operation.

On the other hand, when the pressure PL decreases to the threshold value PB (YES in S46), in step S47, the controller 100 stops the compressor 10 and ends the pump emptying.

Through said control, at a first point of time when the pump emptying operation is started, the controller 100 closes the flow control valve 72 to store the liquid refrigerant in the receiver 73. Then, at a second point of time when the amount of the liquid refrigerant in the receiver 73 increases and the efficiency of the condenser 20 decreases, the controller 100 slightly opens the flow control valve 72 to improve the efficiency of the heat exchanger 30 and promote condensation of the refrigerant in the first H1 channel. This can reduce the time required to complete the pump-out operation.

Finally, the present embodiment will be summarized, again, with reference to the drawings. As shown in fig. 1, the present disclosure refers to the outdoor unit 2 of the refrigeration cycle apparatus 1, the outdoor unit 2 being able to be connected to the charging device 3 that includes the first expansion valve 50 corresponding to the "first expansion device" and an evaporator 60. The outdoor unit 2 includes: first flow path F1 configured to form a circulation flow path through which refrigerant circulates, when connected to the charging device 3; compressor 10 and condenser 20 arranged in the first flow path F1; second flow path F2 configured to branch from a branch point in the first flow path F1 downstream of the condenser 20 in a direction in which the refrigerant circulates, and to return, to the compressor 10, the refrigerant that has passed through of capacitor 20; second expansion valve 71 corresponding to the "second expansion device", receiver 73 and flow control valve 72 arranged in the second flow path F2 in order from the branch point; heat exchanger 30 having a first channel H1 and a second channel H2 and configured to exchange heat between the refrigerant flowing in the first channel H1 and the refrigerant flowing in the second channel H2; and controller 100.

The first channel H1 of the heat exchanger 30 is arranged between the condenser 20 and the branch point in the first flow path F1. The second channel H2 of the heat exchanger 30 is arranged between the flow control valve 72 and the compressor 10 in the second flow path F2. The flow control valve 72 is configured to adjust an expulsion flow rate of liquid refrigerant from the receiver 73.

The controller 100 is configured to control the compressor 10 and the flow control valve 72. When a pump dump operation is initiated to recover the refrigerant in the receiver 73, the controller 100 is configured to control a control state of the compressor 10 and the flow control valve 72, at a first time point, in a first state in which the flow control valve 72 is closed while the compressor 10 is in operation. During the pump dump operation, the controller 100 is configured to transition, at a second time point after the first time point, the control state of the first state to a second state in which the flow control valve 72 is open while the compressor 10 is running.

As the pumping operation continues, recovery of the refrigerant in the receiver 73 continues, and therefore, the amount of the liquid refrigerant in the receiver 73 gradually increases. Consequently, the amount of the liquid refrigerant in the receiver 73 at the second time point is greater than the amount of the liquid refrigerant in the receiver 73 at the first time point.

Preferably, when a difference between the outdoor air temperature and the condensation temperature of the refrigerant in the condenser 20 is less than a threshold value, the controller 100 controls the control state of the compressor 10 and the flow control valve 72 in the second state. In this way, even when the difference between the outside air temperature TA and the refrigerant temperature T1 in the condenser 20 is lower and the efficiency of the condenser 20 is reduced in the phase in which the recovery of the liquid refrigerant in the receiver 73, it is possible to improve the efficiency of the heat exchanger 30 and also continue the recovery of the liquid refrigerant.

It should be noted that, when the opening degree of the flow control valve 72 in the second state is set to full open for a long time, the amount of the liquid refrigerant in the receiver 73 decreases. Consequently, in the second state, it is only necessary to open the flow control valve 72 by a slight degree of opening that can cause an annular flow of the liquid refrigerant in the second channel H2 of the heat exchanger 30, or repeat the opening of the flow control valve 72 for a short period of time and close the flow control valve 72. In this way, the efficiency of heat exchange in the heat exchanger 30 is improved and the refrigerant passing through is condensed. of the first channel H1 in the heat exchanger 30, promoting the recovery of the liquid refrigerant.

More preferably, the controller 100 is configured to set the rotation speed of the compressor 10 in the second state to be greater than the rotation speed of the compressor 10 in the first state. This can reduce the time to recover the remaining refrigerant that has become less condensed because recovery has continued.

Although the present embodiment has been described illustrating a refrigeration machine including a refrigeration cycle apparatus 1, the refrigeration cycle apparatus 1 can be used in an air conditioner or the like.

It should be understood that the embodiment disclosed herein is illustrative and not restrictive in every respect. The scope of the present invention is defined by the scope of the claims, rather than by the description of the embodiment described above, and is intended to include any modifications within the scope defined by the claims.

List of reference signs

1: refrigeration cycle apparatus; 2: outdoor unit; 3: charging device; 10: compressor; 20: capacitor; 22: fan; 28: shut-off valve; 30: heat exchanger; 71: second expansion valve; 50: first expansion valve; 60: evaporator; 70: shutter device; 72: flow control valve; 73: receiver; 80, 81, 82, 83, 84, 85, 88, 89, 91, 92, 94, 96: tube; 93: degassing tube; 100: controller; 104: memory; 110, 111: pressure sensor; 120, 121, 122, 123: temperature sensor; F1: first flow path; F2: second flow path; G1: suction hole; G2: discharge hole; G3: intermediate pressure orifice; H1: first channel; H2: second channel.

Claims (5)

1 . An outdoor unit (2) of a refrigeration cycle apparatus (1), the outdoor unit (2) being able to be connected to a charging device (3) that includes a first expansion device (50) and an evaporator (60), comprising the outdoor unit (2): a first flow path (F1) configured to form a circulation flow path through which refrigerant circulates, when connected to the charging device (3); a compressor (10) and a condenser (20) arranged in the first flow path (F1); a second flow path (F2) configured to branch from a branch point in the first flow path (F1) downstream of the condenser (20) in a direction in which the refrigerant circulates, and to return, to the compressor (10 ), the refrigerant that has passed through the condenser (20); a second expansion device (71), a receiver (73) and a flow control valve (72) arranged in the second flow path (F2) in order from the branch point; a heat exchanger (30) having a first channel (H1) and a second channel (H2) and configured to exchange heat between the refrigerant flowing in the first channel (H1) and the refrigerant flowing in the second channel (H2 ), and a controller (100) configured to control the compressor (10) and the flow control valve (72); in which the first channel (H1) of the heat exchanger (30) is arranged between the condenser (20) and the branch point in the first flow path (F1), the second channel (H2) of the heat exchanger (30) is arranged between the flow control valve (72) and the compressor (10) in the second flow path (F2), and The controller (100) is configured to control the flow control valve (72) to adjust an expulsion flow rate of liquid refrigerant from the receiver (73), characterized in that The controller (100) is configured to, when a pump emptying operation is initiated to recover the refrigerant in the receiver (73), establish a control state of the compressor (10) and the flow control valve (72). , at a first point in time, in a first state in which the flow control valve (72) is closed while the compressor (10) is in operation, and The controller (100) is configured to, during the pump emptying operation, at a second time point after the first time point, change the control state of the first state to a second state in which the control valve of flow (72) is open while the compressor (10) is running. 2 . The outdoor unit (2) according to claim 1, wherein the controller (100) is configured to, when a difference between the outdoor air temperature and the condensation temperature of the refrigerant in the condenser (20) is less than a threshold value, set the control state of the compressor (10) and the flow control valve (72) to the second state. 3 . The outdoor unit (2) according to claim 2, wherein the controller (100) is configured to control the compressor (10) so that a rotation speed of the compressor (10) in the second state is greater than a rotation speed of the compressor (10) in the first state. 4 . The outdoor unit (2) according to claim 1, wherein the controller (100) is configured to control the compressor (10) and the flow control valve (72) so that an amount of the liquid refrigerant in the receiver (73) at the second time point is greater than an amount of the liquid refrigerant in the receiver (73) at the first time point. 5 . A refrigeration cycle apparatus comprising: the outdoor unit (2) according to any one of claims 1 to 4; and the charging device (3).