JP7199554B2 - Outdoor unit and refrigeration cycle equipment - Google Patents

Description

The present invention relates to an outdoor unit and a refrigerating cycle device.

In a refrigeration cycle apparatus, an excess or deficiency in the amount of refrigerant causes deterioration in the performance of the refrigeration system and damage to constituent equipment. International Publication No. 2017/199391 (Patent Literature 1) discloses a refrigeration cycle device that prevents a compressor from malfunctioning by detecting a refrigerant shortage.

WO2017/199391

A refrigeration cycle device is known that has an injection passage for depressurizing and lowering the temperature of a portion of the liquid refrigerant flowing out of the condenser and returning it to the compressor. The refrigerant of the compressor can be cooled by the injection channel. International Publication No. 2017/199391 (Patent Document 1) discloses a refrigerating device having an injection flow path in addition to a general refrigerating device, and detects refrigerant shortage before the compressor fails. there is

In general, when the refrigerant enclosed in the refrigerant circuit runs short due to insufficient charge or leakage, the temperature of the refrigerant discharged from the compressor rises above a target temperature, resulting in a decrease in efficiency. Therefore, it is desirable to detect a refrigerant shortage progressing due to a refrigerant leak or the like as early as possible, even at a stage where the refrigerant shortage does not lead to a compressor failure or the like.

SUMMARY OF THE INVENTION An object of the present invention is to provide an outdoor unit and a refrigeration cycle apparatus capable of detecting refrigerant shortage at 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 connecting with a load device, a first flow path, a compressor, a condenser, a second flow path, a first expansion valve, and a liquid receiver. , a second expansion valve, and a controller. The first flow path extends from the refrigerant inlet port to the refrigerant outlet port and forms a circulation flow path through which the refrigerant circulates together with the load device. A compressor and a condenser are sequentially arranged in the first flow path from the refrigerant inlet port to the refrigerant outlet port. A second flow path branches from a portion of the first flow path between the condenser and the refrigerant outlet port and is configured to return refrigerant that has passed through the condenser back to the compressor. The first expansion valve, the liquid receiver, and the second expansion valve are arranged in the second flow path in order from the branch point of the second flow path from the first flow path. A control device controls the compressor, the first expansion valve, and the second expansion valve. The control device notifies that the refrigerant is insufficient when the time during which the degree of opening of the second expansion valve is at the upper limit degree of opening exceeds the determination time.

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

1 is an overall configuration diagram of a refrigeration cycle apparatus according to Embodiment 1. FIG. 4 is a flow chart for explaining control of the first expansion valve 71. FIG. 7 is a flowchart for explaining control of a second expansion valve 72; 4 is a graph showing the relationship between the progress of refrigerant shortage when refrigerant leakage occurs and the degree of opening of the expansion valve of the outdoor unit. FIG. 6 is an overall configuration diagram of a refrigeration cycle apparatus according to Embodiment 2;

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. A plurality of embodiments will be described below, but appropriate combinations of the configurations described in the respective embodiments have been planned since the filing of the application. The same or corresponding parts in the drawings are denoted by the same reference numerals, and the description thereof will not be repeated.

Embodiment 1.
FIG. 1 is an overall configuration diagram of a refrigeration cycle apparatus according to Embodiment 1. FIG. Note that FIG. 1 functionally shows the connection relationship and arrangement configuration of each device in the refrigeration cycle apparatus, and does not necessarily show the arrangement in a physical space.

Referring to FIG. 1, the refrigeration cycle device 1 includes an outdoor unit 2, a load device 3, and pipes 84,88. The outdoor unit 2 has a refrigerant outlet port PO2 and a refrigerant inlet port PI2 for connecting with the load device 3 . The load device 3 has a refrigerant outlet port PO3 and a refrigerant inlet port PI3 for connecting with the outdoor unit 2 . A pipe 84 connects the refrigerant outlet port PO2 of the outdoor unit 2 and the refrigerant inlet port PI3 of the load device 3 . A 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 device 1 is configured to be connected to the load device 3 . The outdoor unit 2 includes a compressor 10 having an intake 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 which is an expansion device, an evaporator 60 and pipes 85 , 86 and 87 . Evaporator 60 is configured to exchange heat between the air and the refrigerant. In the refrigeration cycle device 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 . Note that the expansion valve 50 may be an electronic expansion valve capable of reducing the pressure of the refrigerant.

The compressor 10 compresses the refrigerant sucked from the pipe 89 and discharges it to the pipe 80 . Compressor 10 can arbitrarily change the driving frequency by inverter control. In addition, the compressor 10 is provided with an intermediate pressure port G3, and the refrigerant from the intermediate pressure port G3 can flow into the intermediate portion of the compression process. Compressor 10 is configured to adjust its rotational speed according to a control signal from control device 100 . By adjusting the rotational speed of the compressor 10, the circulation amount of the refrigerant is adjusted, and the capacity of the refrigeration cycle device 1 can be adjusted. Various types can be adopted for the compressor 10, for example, a scroll type, a rotary type, a screw type, etc. can be adopted.

Condenser 20 is configured such that the high-temperature, high-pressure gas refrigerant discharged from compressor 10 exchanges heat (radiates heat) with the outside air. This heat exchange causes the gas refrigerant to condense and change to a liquid phase. Refrigerant discharged from compressor 10 to pipe 80 is condensed and liquefied in condenser 20 and flows out to pipe 81 . A fan 22 is attached to the condenser 20 to send outside air to increase the efficiency of heat exchange. The fan 22 supplies outside air to the condenser 20 with which the refrigerant exchanges heat in the condenser 20 . By adjusting the rotational speed of the fan 22, the pressure of the refrigerant on the discharge side of the compressor 10 (high-pressure side pressure) can be adjusted.

The outdoor unit 2 includes a first 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 first flow path F1 forms a circulation flow path through which the refrigerant circulates together with the flow path in which the expansion valve 50 and the evaporator 60 of the load device 3 are arranged. Hereinafter, this circulation flow path is also referred to as the "main refrigerant circuit" of the refrigeration cycle.

The outdoor unit 2 includes pipes 91, 92, 93, and 94 for flowing the refrigerant from the portion between the outlet of the condenser 20 and the refrigerant outlet port PO2 of the circulation flow path to the intermediate pressure port G3 of the compressor 10. The second flow path F2 is further provided. Hereinafter, the second flow path F2 that branches from the main refrigerant circuit and feeds the refrigerant to the compressor 10 is also referred to as an "injection flow path".

The outdoor unit 2 further includes a first expansion valve 71, a liquid receiver 73, a second expansion valve 72, and a flow rate limiting device 70 arranged in the second flow path F2. The liquid receiver 73 stores the liquid refrigerant. The first expansion valve 71 is arranged between a pipe 91 branched from the main refrigerant circuit and a pipe 92 connected to the inlet of the liquid receiver 73 . A pipe 93 connects the gas discharge port of the liquid receiver 73 and the pipe 94 and discharges the refrigerant gas in the liquid receiver 73 . The flow rate limiting device 70 is arranged between the pipes 93 and 94 to limit the flow rate of the refrigerant gas. A capillary tube, for example, can be used as the flow restrictor 70 .

A pipe 91 is a pipe that branches off from the main refrigerant circuit and allows the refrigerant to flow into the liquid receiver 73 . The first expansion valve 71 is an electronic expansion valve capable of reducing the pressure of the refrigerant in the high pressure section of the main refrigerant circuit to an intermediate pressure. The liquid receiver 73 is a container capable of separating the vapor phase and the liquid phase of the pressure-reduced two-phase refrigerant in the container, storing the refrigerant, and adjusting the circulation amount of the refrigerant in the main refrigerant circuit. A pipe 93 connected to the upper part of the liquid receiver 73 and a pipe 94 connected to the lower part of the liquid receiver 73 are used to take out the refrigerant separated into gas refrigerant and liquid refrigerant in the liquid receiver 73 in a separated state. is the plumbing. The second expansion valve 72 is provided on the pipe 94 . The second 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 the liquid receiver 73 in the injection flow path in this way, it becomes easy to ensure the degree of supercooling in the pipe 81, which is a liquid pipe. This is because gas refrigerant generally exists in the liquid receiver 73, and the temperature of the refrigerant reaches the saturation temperature.

The outdoor unit 2 further includes pressure sensors 110 , 111 , 112 , temperature sensors 120 , 121 , and a controller 100 that controls the compressor 10 , the first expansion valve 71 and the second expansion valve 72 .

Pressure sensor 110 detects pressure PL at the suction port of compressor 10 and outputs the detected value to control device 100 . Pressure sensor 111 detects pressure PH of refrigerant discharged from compressor 10 and outputs the detected value to control device 100 . Pressure sensor 112 detects pressure P<b>1 of refrigerant flowing out of condenser 20 and outputs the detected value to control device 100 .

Temperature sensor 120 detects temperature TH of refrigerant discharged from compressor 10 and outputs the detected value to control device 100 . Temperature sensor 121 detects temperature T<b>1 of refrigerant in pipe 81 at the outlet of condenser 20 and outputs the detected value to control device 100 .

In the present embodiment, the second flow path F2 controls the temperature TH of the refrigerant discharged from the compressor 10 by flowing into the compressor 10 the refrigerant whose temperature has been lowered by pressure reduction. In addition, the amount of refrigerant in the main refrigerant circuit can be adjusted by the liquid receiver 73 installed on the second flow path F2.

The control device 100 includes a CPU (Central Processing Unit) 102, a memory 104 (ROM (Read Only Memory) and RAM (Random Access Memory)), an input/output buffer (not shown) for inputting and outputting various signals, and the like. Consists of The CPU 102 expands a program stored in the ROM into the RAM or the like and executes it. The program stored in the ROM is a program in which processing procedures of the control device 100 are described. The control device 100 controls each device in the outdoor unit 2 according to these programs. This control is not limited to processing by software, and processing by dedicated hardware (electronic circuit) is also possible.

The control device 100 feedback-controls the first expansion valve 71 so that the temperature TH of the refrigerant discharged from the compressor 10 matches the target temperature.

FIG. 2 is a flow chart for explaining the control of the first expansion valve 71. As shown in FIG. When the temperature TH of the refrigerant discharged from the compressor 10 is higher than the target temperature (YES in S21), the controller 100 increases the opening of the first expansion valve 71 (S22). As a result, the amount of refrigerant flowing into the intermediate pressure port G3 via the liquid receiver 73 increases, so 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 reduces the opening of the first expansion valve 71 (S24). As a result, the amount of refrigerant flowing into the intermediate pressure port G3 via the liquid receiver 73 is reduced, so the temperature TH rises.

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

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

Further, in order to ensure the subcooling degree SC of the refrigerant at the outlet of the condenser 20 during normal operation, the control device 100 controls the second expansion valve 72 so that the temperature T1 of the refrigerant at the outlet of the condenser 20 matches the target temperature. the feedback control. At this time, in the first embodiment, detection of refrigerant shortage is also performed at the same time.

FIG. 3 is a flow chart for explaining the control of the second expansion valve 72. As shown in FIG. Control device 100 calculates degree of subcooling SC of the refrigerant at the outlet of condenser 20 based on temperature T1 and pressure (approximate by PH) of condenser 20 in steps S31 and S33. Specifically, the control device 100 calculates the degree of supercooling SC by subtracting the temperature T1 from the saturation temperature of the refrigerant corresponding to the pressure PH. A conversion table for obtaining the saturation temperature of the refrigerant corresponding to each pressure is stored in memory 104 of control device 100 in advance. The control device 100 then compares the calculated degree of supercooling SC with a target value. This target value is, for example, 5K (Kelvin). If the degree of supercooling SC is greater than the target value (YES in S31), the controller 100 reduces the degree of opening of the second expansion valve 72 (S32). As a result, the amount of liquid refrigerant discharged from the liquid receiver 73 decreases and the amount of liquid refrigerant in the liquid receiver 73 increases. As it rises, the degree of supercooling SC decreases.

On the other hand, if the subcooling degree SC of the refrigerant at the outlet of the condenser 20 is smaller than the target value (NO in S31 and YES in S33), the control device 100 determines in step S34 that the degree of opening of the second expansion valve 72 is Determine whether it is fully open. Here, fully open indicates that the degree of opening of the second expansion valve 72 is the upper limit.

If the opening of the second expansion valve 72 is not fully open (NO in S34), the control device 100 increases the opening of the second expansion valve 72 (S35). As a result, the amount of liquid refrigerant discharged from the liquid receiver 73 increases and the amount of liquid refrigerant stored in the liquid receiver 73 decreases. decreases, the degree of supercooling SC increases.

On the other hand, if the degree of opening of the second expansion valve 72 is fully open (YES in S34), the control device 100 determines in step S36 whether or not the state in which the second expansion valve 72 is fully open has continued for the determination time. do.

If the state in which the second expansion valve 72 is fully open has not continued for the determination time (NO in S36), the control device 100 maintains the degree of opening of the second expansion valve 72 in the fully open state.

On the other hand, if the state in which the second expansion valve 72 is fully open continues for the determination time (YES in S36), in step S37, the control device 100 issues an alarm to the notification device 101 indicating that the refrigerant is insufficient. output. The notification device 101 is, for example, a display device such as a liquid crystal display, a warning lamp, or the like, and may be a device that transmits a warning signal to an external device via a communication line.

After executing any one of steps S32, S35, and S37, control device 100 advances the process to step S38. Further, when the supercooling degree 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 maintains the current opening degree and proceeds to step S38. proceed. In these cases, the process is temporarily returned to the main routine, but the process of the flow chart of FIG. 3 is repeatedly executed at regular time intervals.

FIG. 4 is a graph showing the relationship between the progress of refrigerant shortage when refrigerant leakage occurs and the degree of opening of the expansion valve of the outdoor unit. The degree of refrigerant shortage increases as the progress progresses from D0 to D3.

When the degree of progress is from D0 to D1, the amount of refrigerant is not yet insufficient, and liquid refrigerant is present in the liquid receiver 73 . At this stage, the temperature of the refrigerant discharged from the compressor 10 is appropriately controlled by increasing the degree of opening of the second expansion valve 72 to full open. However, the degree of supercooling SC of the refrigerant at the outlet of the condenser 20 gradually decreases, and at the degree of progress D1, the degree of supercooling SC becomes zero.

When the degree of progress is D1 to D2, the subcooling degree SC of the refrigerant at the outlet of the condenser 20 is zero, but the temperature of the refrigerant discharged from the compressor 10 is still properly controlled. However, the amount of liquid refrigerant in the liquid receiver 73 decreases, and no liquid refrigerant exists inside the liquid receiver 73 at the degree of progress D2. At this stage, the degree of opening of the second expansion valve 72 is fully open.

At the degrees of progress D2 to D3, the degree of supercooling SC of the refrigerant at the outlet of the condenser 20 is zero, and no liquid refrigerant exists inside the liquid receiver 73 . At this stage, the degree of opening of the first expansion valve 71 is increased in order to increase the amount of refrigerant flowing into the injection passage, but the temperature TH of the refrigerant discharged from the compressor 10 rises above the optimal state. put away. Then, at the degree of progress D3, the opening degree of the first expansion valve 71 is fully opened.

Referring to FIG. 4, both the first expansion valve 71 and the second expansion valve 72 are fully opened in the course of the refrigerant shortage. Determining the refrigerant shortage based on the degree of opening of the expansion valve 72 can detect the refrigerant shortage at an early stage. In the present embodiment, it is determined that there is a refrigerant shortage when the time at which the second expansion valve 72 is fully opened reaches the determination time, so the user can be notified of the refrigerant shortage at an early stage. .

Embodiment 2.
In the first embodiment, the case of using a refrigerant whose subcooling degree SC can be calculated from the temperature T1 and the pressure PH, that is, the refrigerant whose pressure in the condenser is less than the critical pressure is used. In recent years, the adoption of natural refrigerants with a low global warming potential has been studied, and refrigerants such as CO ₂ that are used at a pressure above the critical pressure in the condenser may also be adopted. In the second embodiment, detection of refrigerant shortage when such a refrigerant is used will be described.

FIG. 5 is an overall configuration diagram of a refrigeration cycle apparatus according to Embodiment 2. FIG. Note that FIG. 5 functionally shows the connection relationship and arrangement configuration of each device in the refrigeration cycle apparatus, and does not necessarily show the arrangement in a physical space.

Referring to FIG. 5, the refrigeration cycle device 1A includes an outdoor unit 2A, a load device 3, and pipes 84,88. Since load device 3 and pipes 84 and 88 are the same as those of the first embodiment, description thereof will not be repeated.

The outdoor unit 2A includes a temperature sensor 123 in place of the pressure sensor 112 and a control device 100A in place of the control device 100 in the configuration of the outdoor unit 2 shown in FIG. The rest of the configuration of outdoor unit 2A is the same as that of outdoor unit 2, so description will not be repeated.

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

The control device 100A includes a CPU 102, a memory 104, an input/output buffer (not shown) for inputting/outputting various signals, and the like. The CPU 102 expands a program stored in the ROM into the RAM or the like and executes it. The program stored in the ROM is a program describing the processing procedure of the control device 100A. The controller 100A controls each device in the outdoor unit 2A according to these programs. This control is not limited to processing by software, and processing by dedicated hardware (electronic circuit) is also possible.

The control device 100A feedback-controls the first expansion valve 71 so that the temperature TH of the refrigerant discharged from the compressor 10 matches the target temperature. Since the control of first expansion valve 71 is the same as the control of the first embodiment shown in FIG. 2, description thereof will not be repeated.

In addition, in order to ensure the subcooling degree SC of the refrigerant at the outlet of the condenser 20 during normal operation, the control device 100A controls the second expansion valve 72 so that the temperature T1 of the refrigerant at the outlet of the condenser 20 matches the target temperature. the feedback control. At this time, in the second embodiment, detection of refrigerant shortage is also performed at the same time.

In this specification, for ease of explanation, the condenser 20 is also used when cooling a refrigerant such as CO ₂ in a supercritical state. Further, in this specification, for ease of explanation, the amount of decrease from the reference temperature of the refrigerant in the supercritical state is also referred to as the degree of supercooling SC. In Embodiment 2, the reference temperature is the outside air temperature TA+α measured by temperature sensor 123, and the target value of the amount of decrease is, for example, 5 K (Kelvin).

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

When the pressure in the condenser 20 exceeds the critical pressure as in the second embodiment, if the liquid receiver 73 is provided in the intermediate pressure portion, the pressure in the high pressure portion of the main refrigerant circuit is high and the refrigerant is in a supercritical state. Even in the case of , it is possible to store intermediate-pressure liquid refrigerant inside the liquid receiver 73 . Therefore, the design pressure of the container of the liquid receiver 73 can be made lower than that of the high-pressure part, and cost reduction can be achieved by making the container thinner.

The outdoor unit and the refrigeration cycle apparatus of Embodiments 1 and 2 described above will be summarized with reference to the drawings again.

The present disclosure relates to an outdoor unit 2 of a refrigeration cycle device 1 and an outdoor unit 2A of a refrigeration cycle device 1A configured to be connected to a load device 3 including an expansion valve 50 and an evaporator 60, which are expansion devices. The outdoor unit 2 shown in FIG. 1 and the outdoor unit 2A shown in FIG. 20, a second flow path F2, a first expansion valve 71, a liquid receiver 73, a second expansion valve 72, and a control device 100 or 100A. The first 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 in which the refrigerant circulates together with the load device 3. The compressor 10 and the condenser 20 are arranged in order from the refrigerant inlet port PI2 toward the refrigerant outlet port PO2 in the first flow path F1. The second flow path F2 branches from a portion of the first flow path F1 between the condenser 20 and the refrigerant outlet port PO2 and is configured to return the refrigerant that has passed through the condenser 20 to the compressor 10 . The first expansion valve 71, the liquid receiver 73, and the second expansion valve 72 are arranged in the second flow path F2 in order from the branch point of the second flow path F2 from the first flow path F1. Controllers 100 and 100A are configured to control compressor 10 , first expansion valve 71 and second expansion valve 72 . Control devices 100 and 100A notify that the refrigerant is insufficient when the time period during which the degree of opening of second expansion valve 72 is at the upper limit degree of opening exceeds the determination time.

By detecting the refrigerant shortage in this way, in the configuration in which the liquid receiver 73 is arranged in the injection flow path, the refrigerant shortage can be detected early, and the deterioration of the performance of the refrigeration cycle device and the continuation of the refrigerant leakage can be prevented. can be done.

Preferably, the outdoor unit 2 shown in FIG. 1 and the outdoor unit 2A shown in FIG. 5 further include a first temperature sensor 121 that detects the temperature T1 of the refrigerant outlet portion of the condenser 20 in the first flow path F1. Control devices 100 and 100A are configured to control the degree of opening of second expansion valve 72 according to the output of first temperature sensor 121 .

More preferably, the outdoor unit 2 shown in FIG. 1 further includes a pressure sensor 111 that detects the refrigerant pressure PH at the refrigerant outlet portion of the condenser 20 in the first flow path F1. The control device 100 controls the amount of refrigerant calculated based on the output of the first temperature sensor 121 and the output of the pressure sensor 111 when the time during which the degree of opening of the second expansion valve 72 is at the upper limit of the degree of opening exceeds the determination time. If the degree of supercooling SC does not reach the target value, it is determined that the refrigerant is insufficient.

More preferably, the refrigerant used in the configuration shown in FIG. 1 is a refrigerant that is used with the pressure in the condenser 20 below the critical pressure.

More preferably, the outdoor unit 2A shown in FIG. 5 further includes a second temperature sensor 123 that detects the temperature TA of the outside air supplied to the condenser 20. As shown in FIG. The control device 100A determines that the time during which the degree of opening of the second expansion valve 72 is at the upper limit degree of opening exceeds the determination time, and the difference between the temperature detected by the first temperature sensor 121 and the temperature detected by the second temperature sensor 123 is determined. If it is smaller than the value, it is judged that the refrigerant is insufficient.

More preferably, the refrigerant used in the configuration shown in FIG. 5 is carbon dioxide used at the pressure in the condenser 20 above 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 this time should be considered as examples and not restrictive in all respects. The scope of the present invention is indicated by the scope of the claims rather than the description of the above-described embodiments, and is intended to include all modifications within the meaning and scope equivalent to the scope of the claims.

Reference Signs List 1, 1A refrigerating cycle device, 2, 2A outdoor unit, 3 load device, 10 compressor, 20 condenser, 22 fan, 50 expansion valve, 60 evaporator, 70 flow limiter, 71 first expansion valve, 72 second second expansion valve, 73 receiver, 80, 81, 84, 85, 88, 89, 91, 92, 93, 94 piping, 100, 100A control device, 101 notification device, 104 memory, 110, 111, 112 pressure sensor, 120, 121, 123 temperature sensor, F1, F2 flow path, G1 suction port, G2 discharge port, G3 intermediate pressure port, PI2, PI3 refrigerant inlet port, PO2, PO3 refrigerant outlet port.

Claims (7)

An outdoor unit of a refrigeration cycle apparatus configured to be connected to a load device including an expansion device and an evaporator,
a refrigerant outlet port and a refrigerant inlet port for connecting with the load device;
a first flow path extending from the refrigerant inlet port to the refrigerant outlet port and forming a circulation flow path in which the refrigerant circulates together with the load device;
a compressor and a condenser arranged in order from the refrigerant inlet port to the refrigerant outlet port in the first flow path;
a second flow path branching from a portion of the first flow path between the condenser and the refrigerant outlet port and configured to return the refrigerant that has passed through the condenser to the compressor;
a first expansion valve, a receiver, and a second expansion valve arranged in the second flow path in order from a branch point of the second flow path from the first flow path;
a controller that controls the compressor, the first expansion valve, and the second expansion valve;
The outdoor unit, wherein the control device notifies that the refrigerant is insufficient when a time period during which the degree of opening of the second expansion valve is the upper limit degree of opening exceeds a determination time. further comprising a first temperature sensor that detects the temperature of the refrigerant at the refrigerant outlet portion of the condenser in the first flow path;
The outdoor unit according to claim 1, wherein the control device is configured to control the degree of opening of the second expansion valve according to the output of the first temperature sensor. further comprising a pressure sensor for detecting refrigerant pressure at a refrigerant outlet portion of the condenser in the first flow path;
In the control device, the time during which the degree of opening of the second expansion valve is at the upper limit degree of opening exceeds the determination time and is calculated based on the output of the first temperature sensor and the output of the pressure sensor. 3. The outdoor unit according to claim 2, wherein it is determined that the refrigerant is insufficient when the subcooling degree of the refrigerant does not reach a target value. 4. The outdoor unit according to claim 3, wherein the refrigerant is a refrigerant used at a pressure below the critical pressure in the condenser. further comprising a second temperature sensor that detects the temperature of outside air supplied to the condenser;
The controller controls that the time during which the degree of opening of the second expansion valve is at the upper limit degree of opening exceeds the determination time, and the difference between the temperature detected by the first temperature sensor and the temperature detected by the second temperature sensor 3. The outdoor unit according to claim 2, wherein the refrigerant is judged to be insufficient when is smaller than the judgment value. 6. The outdoor unit according to claim 5, wherein the refrigerant is carbon dioxide used at a pressure above the critical pressure in the condenser. A refrigeration cycle apparatus comprising the outdoor unit according to any one of claims 1 to 6 and the load device.

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