CN114364934B

CN114364934B - Outdoor unit and refrigeration cycle device

Info

Publication number: CN114364934B
Application number: CN201980099971.7A
Authority: CN
Inventors: 石川智隆; 有井悠介; 早坂素
Original assignee: Mitsubishi Electric Corp
Current assignee: Mitsubishi Electric Corp
Priority date: 2019-09-09
Filing date: 2019-09-09
Publication date: 2023-03-21
Anticipated expiration: 2039-09-09
Also published as: EP4030122A4; EP4030122B1; JP7199554B2; WO2021048905A1; CN114364934A; JPWO2021048905A1; DK4030122T3; ES2950759T3; EP4030122A1; FI4030122T3

Abstract

The outdoor unit (2) is provided with a 1 st flow path (F1), a 2 nd flow path (F2), and a control device (100). The compressor (10) and the condenser (20) are disposed in the 1 st flow path (F1) in order from the refrigerant inlet port (PI 2) to the refrigerant outlet port (PO 2). The 2 nd flow path (F2) is configured to branch from a portion between the condenser (20) and the refrigerant outlet port (PO 2) of the 1 st flow path (F1), and to return the refrigerant passing through the condenser (20) to the compressor (10). The 1 st expansion valve (71), the liquid receiver (73), and the 2 nd expansion valve (72) are disposed in the 2 nd flow path (F2) in the order from the branching point of the 1 st flow path (F1) of the 2 nd flow path (F2). A control device (100) controls the compressor (10), the 1 st expansion valve (71), and the 2 nd expansion valve (72). When the time during which the opening degree of the 2 nd expansion valve (72) is the upper limit opening degree exceeds a determination time, the control device (100) reports that the refrigerant is insufficient.

Description

Outdoor unit and refrigeration cycle device

Technical Field

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

Background

In the refrigeration cycle apparatus, excess or deficiency of the amount of refrigerant causes a reduction in the capacity of the refrigeration apparatus and damage to the components. In international publication No. 2017/199391 (patent document 1), a refrigeration cycle apparatus that prevents a failure of a compressor by detecting a shortage of refrigerant is disclosed.

Documents of the prior art

Patent document

Patent document 1: international publication No. 2017/199391

Disclosure of Invention

A refrigeration cycle apparatus having an injection flow path for reducing a pressure of a part of a liquid refrigerant flowing out of a condenser to lower a temperature and returning the reduced pressure to a compressor is known. The refrigerant of the compressor can be cooled by the injection flow path. International publication No. 2017/199391 (patent document 1) discloses a refrigeration apparatus having an injection flow path in addition to a general refrigeration apparatus, and detects a shortage of refrigerant before a failure of a compressor.

In general, when the refrigerant sealed in the refrigerant circuit becomes insufficient due to an insufficient amount of filling or leakage, the refrigeration cycle apparatus becomes inefficient due to an increase in the temperature of the refrigerant discharged from the compressor above a target temperature. Therefore, it is desirable to detect the refrigerant shortage that has progressed due to leakage of the refrigerant or the like as early as possible even in a stage where the failure or the like of the compressor has not been caused due to the refrigerant shortage.

The invention aims to provide an outdoor unit and a refrigeration cycle device capable of detecting insufficient refrigerant in an early stage.

The present disclosure relates to an outdoor unit of a refrigeration cycle apparatus configured to be connected to a load device including an expansion device and an evaporator. The outdoor unit includes a refrigerant outlet port and a refrigerant inlet port for connection to a load device, a 1 st flow path, a compressor, a condenser, a 2 nd flow path, a 1 st expansion valve, a liquid receiver, a 2 nd expansion valve, and a control device. The 1 st flow path is a flow path from the refrigerant inlet port to the refrigerant outlet port, and forms a circulation flow path in which the refrigerant circulates together with the load device. The compressor and the condenser are arranged in order from the refrigerant inlet port to the refrigerant outlet port in the 1 st flow path. The 2 nd flow path is configured to branch from a portion between the condenser and the refrigerant outlet port of the 1 st flow path, and to return the refrigerant passing through the condenser to the compressor. The 1 st expansion valve, the liquid receiver, and the 2 nd expansion valve are disposed in the 2 nd flow path in this order from the branching point of the 1 st flow path of the 2 nd flow path. The control device controls the compressor, the 1 st expansion valve and the 2 nd expansion valve. The control device reports the refrigerant shortage when the time during which the opening degree of the 2 nd expansion valve is the upper limit opening degree exceeds the determination time.

According to the outdoor unit and the refrigeration cycle apparatus including the outdoor unit of the present disclosure, when the refrigerant is insufficient due to leakage of the refrigerant or the like, the refrigerant shortage can be detected at an early stage.

Drawings

Fig. 1 is an overall configuration diagram of a refrigeration cycle apparatus according to embodiment 1.

Fig. 2 is a flowchart for explaining control of the 1 st expansion valve 71.

Fig. 3 is a flowchart for explaining control of the 2 nd expansion valve 72.

Fig. 4 is a graph showing a relationship between the degree of expansion of the refrigerant shortage and the opening degree of the expansion valve of the outdoor unit when the refrigerant leakage occurs.

Fig. 5 is an overall configuration diagram of the refrigeration cycle apparatus according to embodiment 2.

(description of reference numerals)

1. 1A: a refrigeration cycle device; 2. 2A: an outdoor unit; 3: a load device; 10: a compressor; 20: a condenser; 22: a fan; 50: an expansion valve; 60: an evaporator; 70: a flow restriction device; 71: 1 st expansion valve; 72: a 2 nd expansion valve; 73: a liquid receiver; 80. 81, 84, 85, 88, 89, 91, 92, 93, 94: piping; 100. 100A: a control device; 101: a reporting device; 104: a memory; 110. 111, 112: a pressure sensor; 120. 121, 123: a temperature sensor; f1, F2: a flow path; g1: a suction port; g2: a discharge port; g3: an intermediate pressure port; PI2, PI3: a refrigerant inlet port; PO2, PO3: a refrigerant outlet port.

Detailed Description

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. A plurality of embodiments will be described below, but the configurations described in the respective embodiments are intended to be appropriately combined from the first application. In the drawings, the same or corresponding portions are denoted by the same reference numerals, and description thereof will not be repeated.

Embodiment mode 1

Fig. 1 is an overall configuration diagram of a refrigeration cycle apparatus according to embodiment 1. In fig. 1, the connection relationship and arrangement structure of each device in the refrigeration cycle apparatus are functionally shown, and the arrangement in the physical space is not necessarily shown.

Referring to fig. 1, the refrigeration cycle apparatus 1 includes an outdoor unit 2, a load device 3, and

pipes

84 and 88. The outdoor unit 2 has a refrigerant outlet port PO2 and a refrigerant inlet port PI2 for connection with the load device 3. The load device 3 has a refrigerant outlet port PO3 for connection with the outdoor unit 2 and a refrigerant inlet port PI3. The pipe 84 connects the refrigerant outlet port PO2 of the outdoor unit 2 and the refrigerant inlet port PI3 of the load device 3. The pipe 88 connects the refrigerant outlet port PO3 of the load device 3 and the refrigerant inlet port PI2 of the outdoor unit 2.

The outdoor unit 2 of the refrigeration cycle apparatus 1 is connected to a load device 3. The outdoor unit 2 includes a compressor 10 having a suction port G1, a discharge port G2, and an intermediate pressure port G3, a condenser 20, a fan 22, and

pipes

80, 81, and 89.

The load device 3 includes an expansion valve 50 as an expansion device, an evaporator 60, and

pipes

85, 86, and 87. The evaporator 60 is configured to exchange heat between air and refrigerant. In the refrigeration cycle apparatus 1, the evaporator 60 evaporates the refrigerant by absorbing heat from the air in the space to be cooled. The expansion valve 50 is, for example, a temperature expansion valve controlled independently of the outdoor unit 2. The expansion valve 50 may be an electronic expansion valve capable of reducing the pressure of the refrigerant.

Compressor 10 compresses a refrigerant sucked from pipe 89 and discharges the compressed refrigerant to pipe 80. The compressor 10 can arbitrarily change the drive frequency by inverter control. The compressor 10 is provided with an intermediate-pressure port G3, and the refrigerant from the intermediate-pressure port G3 can be made to flow into an intermediate portion of the compression process. The compressor 10 is configured to adjust the rotation speed in accordance with a control signal from the control device 100. The capacity of the refrigeration cycle apparatus 1 can be adjusted by adjusting the rotation speed of the compressor 10 and adjusting the circulation amount of the refrigerant. The compressor 10 can employ various types of compressors, for example, a scroll type, a rotary type, a screw type, and the like can be employed.

The condenser 20 is configured to exchange heat (dissipate heat) between the high-temperature and high-pressure gas refrigerant discharged from the compressor 10 and outside air. By this heat exchange, the gas refrigerant is condensed to change to a liquid phase. The refrigerant discharged from compressor 10 to pipe 80 is condensed and liquefied in condenser 20, and flows out to pipe 81. In order to improve the efficiency of heat exchange, a fan 22 for sending outside air is installed in the condenser 20. The fan 22 supplies the condenser 20 with the external air heat-exchanged with the refrigerant in the condenser 20. The refrigerant pressure on the discharge side (high-pressure-side pressure) of the compressor 10 can be adjusted by adjusting the rotation speed of the fan 22.

The outdoor unit 2 includes a 1 st flow path F1 extending from the refrigerant inlet port PI2 to the refrigerant outlet port PO2 via the compressor 10 and the condenser 20. The 1 st flow path F1 forms a circulation flow path for circulating the refrigerant together with the flow path of the load device 3 in which the expansion valve 50 and the evaporator 60 are arranged. Hereinafter, this circulation flow path is also referred to as a "main refrigerant circuit" of the refrigeration cycle.

The outdoor unit 2 further includes a 2 nd flow path

F2 including pipes

91, 92, 93, and 94, and the

pipes

91, 92, 93, and 94 allow the refrigerant to flow from a portion of the circulation flow path between the outlet of the condenser 20 and the refrigerant outlet port PO2 to the intermediate pressure port G3 of the compressor 10. Hereinafter, the 2 nd flow path F2 branched from the main refrigerant circuit and delivering the refrigerant to the compressor 10 is also referred to as an "injection flow path".

The outdoor unit 2 further includes a 1 st expansion valve 71, a liquid receiver 73, a 2 nd expansion valve 72, and a flow rate limiting device 70, which are disposed in the 2 nd flow path F2. The liquid receiver 73 stores liquid refrigerant. The 1 st expansion valve 71 is disposed between a pipe 91 branched from the main refrigerant circuit and a pipe 92 connected to an inlet of the liquid receiver 73. The pipe 93 connects the gas discharge port of the liquid receiver 73 to the pipe 94, and discharges the refrigerant gas in the liquid receiver 73. The flow rate limiting device 70 is disposed between the pipe 93 and the pipe 94, and limits the flow rate of the refrigerant gas. As the flow rate limiting device 70, for example, a capillary tube can be used.

The pipe 91 branches from the main refrigerant circuit and flows the refrigerant into the liquid receiver 73. The 1 st expansion valve 71 is an electronic expansion valve capable of reducing the pressure of the refrigerant in the high-pressure portion of the main refrigerant circuit to an intermediate pressure. The liquid receiver 73 is a container capable of separating a gas phase and a liquid phase of a two-phase refrigerant decompressed in the container, storing the refrigerant, and adjusting the circulation amount of the refrigerant in the main refrigerant circuit. The pipe 93 connected to the upper portion of the liquid receiver 73 and the pipe 94 connected to the lower portion of the liquid receiver 73 are pipes for taking out the refrigerant separated into the gas refrigerant and the liquid refrigerant in the liquid receiver 73 in a separated state. The 2 nd expansion valve 72 is provided in the pipe 94. The 2 nd expansion valve 72 can adjust the amount of refrigerant in the liquid receiver 73 by adjusting the amount of liquid refrigerant discharged from the pipe 94.

By providing liquid receiver 73 in the injection flow path in this way, the degree of supercooling in pipe 81 as a liquid pipe can be easily ensured. This is because, in general, since the liquid receiver 73 contains a gas refrigerant, the temperature of the refrigerant becomes a saturation temperature, and therefore, when the liquid receiver 73 is disposed in the pipe 81, the degree of supercooling cannot be ensured.

The outdoor unit 2 further includes

pressure sensors

110, 111, and 112,

temperature sensors

120 and 121, and a control device 100 that controls the compressor 10, the 1 st expansion valve 71, and the 2 nd expansion valve 72.

The pressure sensor 110 detects a pressure PL at a suction port portion of the compressor 10, and outputs a detection value thereof to the control device 100. The pressure sensor 111 detects a pressure PH of the refrigerant discharged from the compressor 10, and outputs a detection value thereof to the control device 100. The pressure sensor 112 detects the pressure P1 of the refrigerant flowing out of the condenser 20, and outputs the detected value to the control device 100.

The temperature sensor 120 detects a temperature TH of the refrigerant discharged from the compressor 10, and outputs a detection value thereof to the control device 100. The temperature sensor 121 detects the temperature T1 of the refrigerant in the pipe 81 at the outlet of the condenser 20, and outputs the detected value to the control device 100.

In the present embodiment, the 2 nd flow path F2 controls the temperature TH of the refrigerant discharged from the compressor 10 by allowing the refrigerant reduced in pressure and reduced in temperature to flow into the compressor 10. The refrigerant amount in the main refrigerant circuit can be adjusted by the liquid receiver 73 provided in the 2 nd flow path F2.

The control device 100 includes a CPU (Central Processing Unit) 102, a Memory 104 (a ROM (Read Only Memory) and a RAM (Random Access Memory)), an input/output buffer (not shown) for inputting and outputting various signals, and the like. The CPU102 expands and executes a program stored in the ROM in the RAM or the like. The program stored in the ROM is a program describing a processing procedure of the control device 100. The control device 100 executes control of each device in the outdoor unit 2 in accordance with these programs. This control is not limited to processing by software, and may be processed by dedicated hardware (electronic circuit).

The control device 100 performs feedback control on the 1 st expansion valve 71 so that the temperature TH of the refrigerant discharged from the compressor 10 matches a target temperature.

Fig. 2 is a flowchart for explaining control of the 1 st expansion valve 71. When the temperature TH of the refrigerant discharged from the compressor 10 is higher than the target temperature (yes in S21), the control device 100 increases the opening degree of the 1 st expansion valve 71 (S22). As a result, the refrigerant flowing into the intermediate-pressure port G3 via the liquid receiver 73 increases, and the temperature TH decreases.

On the other hand, when the temperature TH of the refrigerant discharged from the compressor 10 is lower than the target temperature (no in S21 and yes in S23), the control device 100 decreases the opening degree of the 1 st expansion valve 71 (S24). As a result, the refrigerant flowing into the intermediate-pressure port G3 via the liquid receiver 73 decreases, and the temperature TH increases.

If the temperature TH = the target temperature (no in S21 and no in S23), the control device 100 maintains the opening degree of the 1 st expansion valve 71 in the current state.

In this way, the control device 100 controls the opening degree of the 1 st expansion valve 71 so that the temperature TH of the refrigerant discharged from the compressor 10 approaches the target temperature.

In order to ensure the degree of subcooling SC of the refrigerant at the outlet of the condenser 20 during the normal operation, the control device 100 performs feedback control on the 2 nd expansion valve 72 so that the refrigerant temperature T1 at the outlet of the condenser 20 matches the target temperature. In this case, in embodiment 1, the refrigerant shortage is also detected at the same time.

Fig. 3 is a flowchart for explaining control of the 2 nd expansion valve 72. In steps S31 and S33, the control device 100 calculates the degree of subcooling SC of the refrigerant at the outlet of the condenser 20 from the temperature T1 and the pressure of the condenser 20 (approximated by PH). Specifically, the control device 100 calculates the degree of subcooling SC by subtracting the temperature T1 from the saturation temperature of the refrigerant corresponding to the pressure PH. In addition, a conversion table for obtaining the saturation temperature of the refrigerant corresponding to each pressure is stored in advance in the memory 104 of the control device 100. Then, the control device 100 compares the calculated supercooling degree SC with the target value. The target value is, for example, 5K (kelvin). When the degree of subcooling SC is larger than the target value (yes in S31), the control device 100 decreases the opening degree of the 2 nd expansion valve 72 (S32). As a result, the amount of the liquid refrigerant discharged from the liquid receiver 73 decreases, and the amount of the liquid refrigerant in the liquid receiver 73 increases, so that the amount of the refrigerant circulating in the main refrigerant circuit decreases, and the temperature T1 of the refrigerant increases, and the degree of subcooling SC decreases.

On the other hand, if the degree of subcooling SC of the refrigerant at the outlet of the condenser 20 is less than the target value (no in S31 and yes in S33), the control device 100 determines in step S34 whether or not the opening degree of the 2 nd expansion valve 72 is fully open. Here, the fully open means that the opening degree of the 2 nd expansion valve 72 is an upper limit value.

If the opening degree of the 2 nd expansion valve 72 is not fully opened (no in S34), the control device 100 increases the opening degree of the 2 nd expansion valve 72 (S35). As a result, the amount of the liquid refrigerant discharged from the liquid receiver 73 increases, and the amount of the liquid refrigerant accumulated in the liquid receiver 73 decreases, so that the amount of the refrigerant circulating in the main refrigerant circuit increases, and the temperature T1 of the refrigerant decreases, so that the degree of subcooling SC increases.

On the other hand, when the opening degree of the 2 nd expansion valve 72 is fully opened (yes in S34), the control device 100 determines in step S36 whether or not the 2 nd expansion valve 72 is fully opened for the determination time.

If the state in which the 2 nd expansion valve 72 is fully opened does not continue for the determination time (no in S36), the control device 100 maintains the opening degree of the 2 nd expansion valve 72 in the fully opened state.

On the other hand, if the 2 nd expansion valve 72 is fully opened for the determination time (yes in S36), the control device 100 causes the notification device 101 to output an alarm indicating a refrigerant shortage in step S37. The notification device 101 may be a display device such as a liquid crystal display, a warning lamp, or the like, and may transmit a warning signal to an external device via a communication line.

After executing any of steps S32, S35, and S37, control device 100 advances the process to step S38. When the degree of subcooling SC of the refrigerant at the outlet of the condenser 20 is the target value (no in S31 and no in S33), the control device 100 advances the process to step S38 while maintaining the current opening degree as it is. In these cases, the processing temporarily returns to the main routine, but the processing of the flowchart of fig. 3 is repeatedly executed at regular intervals.

Fig. 4 is a graph showing a relationship between the degree of expansion of the refrigerant shortage and the opening degree of the expansion valve of the outdoor unit when the refrigerant leakage occurs. As the degree of progression enters from D0 to D3, the degree of shortage of refrigerant becomes greater.

When the degree of expansion is D0 to D1, the amount of refrigerant is not yet insufficient, and liquid refrigerant is present in the liquid receiver 73. In this stage, the temperature of the discharge refrigerant of the compressor 10 is appropriately controlled by increasing the opening degree of the 2 nd expansion valve 72 to full opening. However, the degree of subcooling SC of the refrigerant at the outlet portion of the condenser 20 gradually decreases, and the degree of subcooling SC becomes zero at the degree of progression D1.

When the degree of expansion is D1 to D2, the degree of subcooling SC of the refrigerant at the outlet portion of the condenser 20 is zero, but the temperature of the refrigerant discharged from the compressor 10 is also controlled appropriately. However, the amount of the liquid refrigerant in the liquid receiver 73 decreases, and at the degree of progress D2, the liquid refrigerant in the liquid receiver 73 does not exist. At this stage, the opening degree of the 2 nd expansion valve 72 is fully opened.

In the degrees of progress D2 to D3, the degree of subcooling SC of the refrigerant at the outlet portion of the condenser 20 is zero, and the liquid refrigerant in the liquid receiver 73 is not present. At this stage, the opening degree of the 1 st expansion valve 71 is increased in order to increase the inflow amount of the refrigerant into the injection flow path, but the temperature TH of the refrigerant discharged from the compressor 10 is higher than the optimum state. Then, at the degree of progress D3, the opening degree of the 1 st expansion valve 71 becomes fully open.

According to fig. 4, while both the 1 st expansion valve 71 and the 2 nd expansion valve 72 are fully open during the occurrence of a refrigerant shortage, the 2 nd expansion valve 72 becomes fully open at an earlier stage, and therefore, when a refrigerant shortage is determined from the opening degree of the 2 nd expansion valve 72, the refrigerant shortage can be detected at an earlier stage. In the present embodiment, since the refrigerant is determined to be insufficient when the time at which the opening degree of the 2 nd expansion valve 72 is in the fully open state reaches the determination time, the refrigerant shortage can be communicated to the user at an early stage.

Embodiment mode 2

In embodiment 1, the description has been given of the case where "the refrigerant whose supercooling degree SC can be calculated from the temperature T1 and the pressure PH, that is, the refrigerant used when the pressure in the condenser is smaller than the critical pressure" is used. In recent years, it has been studied to use natural refrigerants having a low global warming potential, and sometimes to use CO as well ₂ The refrigerant used when the pressure in the condenser is equal to or higher than the critical pressure. In embodiment 2, detection of a refrigerant shortage in the case of using such a refrigerant will be described.

Fig. 5 is an overall configuration diagram of the refrigeration cycle apparatus according to embodiment 2. In fig. 5, the connection relationship and the arrangement structure of the respective devices in the refrigeration cycle apparatus are functionally shown, and the arrangement in the physical space is not necessarily shown.

Referring to fig. 5, the refrigeration cycle apparatus 1A includes an outdoor unit 2A, a load device 3, and

pipes

84 and 88. The load device 3 and the

pipes

84 and 88 are the same as those in embodiment 1, and therefore, description thereof will not be repeated.

The outdoor unit 2A includes a temperature sensor 123 instead of the pressure sensor 112 and a control device 100A instead of the control device 100 in the configuration of the outdoor unit 2 shown in fig. 1. The other configurations of the outdoor unit 2A are the same as those of the outdoor unit 2, and therefore, description thereof will not be repeated.

The temperature sensor 123 detects an outside air temperature TA that is an ambient temperature of the outdoor unit 2A, and outputs a detection value thereof to the control device 100A.

The control device 100A includes a CPU102, a memory 104, an input/output buffer (not shown) for inputting and outputting various signals, and the like. The CPU102 expands and executes a program stored in the ROM in the RAM or the like. The program stored in the ROM is a program describing the processing procedure of the control device 100A. The control device 100 executes control of each device in the outdoor unit 2 in accordance with these programs. This control is not limited to processing by software, and can be performed by dedicated hardware (electronic circuit).

The control device 100A performs feedback control on the 1 st expansion valve 71 so that the temperature TH of the refrigerant discharged from the compressor 10 matches a target temperature. The control of the 1 st expansion valve 71 is the same as that of embodiment 1 shown in fig. 2, and therefore, the description thereof will not be repeated.

Further, the control device 100A performs feedback control on the 2 nd expansion valve 72 so that the refrigerant temperature T1 at the outlet of the condenser 20 coincides with the target temperature in order to ensure the degree of subcooling SC of the refrigerant at the outlet of the condenser 20 during the normal operation. In this case, in embodiment 2, the refrigerant shortage is also detected at the same time.

In this specification, for the sake of easy explanation, the term "supercritical state" is used for CO ₂ Such a case where the refrigerant cools is also referred to as a condenser 20. In the present specification, for the sake of easy description, the amount of decrease from the reference temperature of the refrigerant in the supercritical state is also referred to as the degree of subcooling SC. In embodiment 2, the reference temperature is the temperature TA + α of the outside air measured by the temperature sensor 123, and the target value of the amount of decrease is, for example, 5K (kelvin).

In embodiment 2 as well, by setting the degree of subcooling SC to the difference between the temperature TA + α and the temperature T1, the shortage of refrigerant can be detected early by the processing of the flowchart shown in fig. 3.

When the pressure in the condenser 20 exceeds the critical pressure as in embodiment 2, even when the pressure of the high-pressure portion of the main refrigerant circuit is high and the refrigerant is in a supercritical state when the liquid receiver 73 is provided in the intermediate-pressure portion, the intermediate-pressure liquid refrigerant can be stored in the liquid receiver 73. Therefore, the design pressure of the tank of the liquid receiver 73 can be made lower than the high-pressure portion, and the cost reduction due to the thinning of the tank can be achieved.

The outdoor units and refrigeration cycle devices according to embodiments 1 and 2 described above are summarized again with reference to the drawings.

The present disclosure relates to an outdoor unit 2 of a refrigeration cycle apparatus 1 and an outdoor unit 2A of the refrigeration cycle apparatus 1A configured to be connected to a load device 3 including an expansion valve 50 and an evaporator 60 as expansion devices. The outdoor unit 2 shown in fig. 1 and the outdoor unit 2A shown in fig. 5 include a refrigerant outlet port PO2 and a refrigerant inlet port PI2 for connection to the load device 3, a 1 st flow path F1, the compressor 10, the condenser 20, a 2 nd flow path F2, a 1 st expansion valve 71, a liquid receiver 73, a 2 nd expansion valve 72, and a

control device

100 or 100A. The 1 st flow path F1 is a flow path from the refrigerant inlet port PI2 to the refrigerant outlet port PO2, and forms a circulation flow path for circulating the refrigerant together with the load device 3. The compressor 10 and the condenser 20 are disposed in the 1 st flow path F1 in order from the refrigerant inlet port PI2 to the refrigerant outlet port PO 2. The 2 nd flow path F2 is configured to branch from a portion between the condenser 20 and the refrigerant outlet port PO2 of the 1 st flow path F1, and to return the refrigerant having passed through the condenser 20 to the compressor 10. The 1 st expansion valve 71, the liquid receiver 73, and the 2 nd expansion valve 72 are disposed in the 2 nd flow path F2 in this order from the branching point of the 1 st flow path F1 of the 2 nd flow path F2. The

controllers

100 and 100A are configured to control the compressor 10, the 1 st expansion valve 71, and the 2 nd expansion valve 72. The

control devices

100 and 100A report that the refrigerant is insufficient when the time during which the opening degree of the 2 nd expansion valve 72 is the upper limit opening degree exceeds the determination time.

By detecting the shortage of the refrigerant in this manner, the shortage of the refrigerant can be detected at an early stage in the configuration in which the liquid receiver 73 is disposed in the injection flow path, and the performance of the refrigeration cycle apparatus can be prevented from being lowered and the refrigerant can be prevented from continuously leaking.

Preferably, the outdoor unit 2 shown in fig. 1 and the outdoor unit 2A shown in fig. 5 further include a 1 st temperature sensor 121 that detects a temperature T1 at the refrigerant outlet portion of the condenser 20 in the 1 st flow path F1. The

control devices

100 and 100A are configured to control the opening degree of the 2 nd expansion valve 72 based on the output of the 1 st temperature sensor 121.

More preferably, the outdoor unit 2 shown in fig. 1 further includes a pressure sensor 111 for detecting the pressure PH of the refrigerant at the refrigerant outlet portion of the condenser 20 in the 1 st flow path F1. The control device 100 determines that the refrigerant is insufficient when the time when the opening degree of the 2 nd expansion valve 72 is the upper limit opening degree exceeds the determination time and the degree of subcooling SC of the refrigerant calculated from the output of the 1 st temperature sensor 121 and the output of the pressure sensor 111 does not reach the target value.

It is further preferable that the refrigerant used in the configuration shown in fig. 1 is a refrigerant used when the pressure in the condenser 20 is less than the critical pressure.

More preferably, the outdoor unit 2A shown in fig. 5 further includes a 2 nd temperature sensor 123 that detects a temperature TA of the outside air supplied to the condenser 20. The control device 100A determines that the refrigerant is insufficient when the time when the opening degree of the 2 nd expansion valve 72 is the upper limit opening degree exceeds the determination time and the difference between the temperature detected by the 1 st temperature sensor 121 and the temperature detected by the 2 nd temperature sensor 123 is less than the determination value.

More preferably, the refrigerant used in the configuration shown in fig. 5 is carbon dioxide used when the pressure in the condenser 20 is equal to or higher than the critical pressure.

In another aspect, the present disclosure relates to a refrigeration cycle apparatus including any one of the outdoor units described above and a load device.

The embodiments disclosed herein are to be considered in all respects as illustrative and not restrictive. The scope of the present invention is defined by the claims rather than the description of the above embodiments, and is intended to include meanings equivalent to the claims and all modifications within the scope.

Claims

1. An outdoor unit of a refrigeration cycle device configured to be connected to a load device including an expansion device and an evaporator, the outdoor unit comprising:

a refrigerant outlet port and a refrigerant inlet port for connection with the load device;

a 1 st flow path that is a flow path from the refrigerant inlet port to the refrigerant outlet port, the 1 st flow path forming a circulation flow path for circulating a refrigerant together with the load device;

a compressor and a condenser that are arranged in the 1 st flow path in this order from the refrigerant inlet port toward the refrigerant outlet port;

a 2 nd flow path configured to branch from a portion between the condenser and the refrigerant outlet port of the 1 st flow path and return the refrigerant passing through the condenser to the compressor;

a 1 st expansion valve, a liquid receiver, and a 2 nd expansion valve, which are disposed in the 2 nd flow path in order from a branch point of the 1 st flow path in the 2 nd flow path; and

a control device for controlling the compressor, the 1 st expansion valve and the 2 nd expansion valve,

the control device reports the refrigerant shortage when a time during which the opening degree of the 2 nd expansion valve is the upper limit opening degree exceeds a determination time.

2. The outdoor unit of claim 1,

further comprising a 1 st temperature sensor for detecting a temperature of the refrigerant at a refrigerant outlet portion of the condenser in the 1 st flow path,

the control device is configured to control the opening degree of the 2 nd expansion valve based on an output of the 1 st temperature sensor.

3. The outdoor unit of claim 2,

further comprising a pressure sensor for detecting a refrigerant pressure at a refrigerant outlet portion of the condenser in the 1 st flow path,

the control device determines that the refrigerant is insufficient when a time when the opening degree of the 2 nd expansion valve is the upper limit opening degree exceeds the determination time and a degree of subcooling of the refrigerant calculated from the output of the 1 st temperature sensor and the output of the pressure sensor does not reach a target value.

4. The outdoor unit of claim 3,

the refrigerant is a refrigerant used when the pressure in the condenser is less than a critical pressure.

5. The outdoor unit of claim 2,

further comprising a 2 nd temperature sensor for detecting the temperature of the outside air supplied to the condenser,

the control device determines that the refrigerant is insufficient when a time when the opening degree of the 2 nd expansion valve is the upper limit opening degree exceeds the determination time and a difference between a detected temperature of the 1 st temperature sensor and a detected temperature of the 2 nd temperature sensor is less than a determination value.

6. The outdoor unit of claim 5,

the refrigerant is carbon dioxide used when the pressure in the condenser is equal to or higher than a critical pressure.

7. A refrigeration cycle device is provided with:

an outdoor unit according to any one of claims 1 to 6; and

the load device.