ES2950759T3 - Outdoor unit and refrigeration cycle apparatus - Google Patents

Abstract

An outdoor unit (2) is provided with: a first flow path (F1); a second flow path (F2); and a control device (100). A compressor (10) and a condenser (20) are arranged in order from a refrigerant inlet port (PI2) to a refrigerant outlet port (PO2) in the first flow path (F1). The second flow path (F2) branches from a portion between the condenser (20) and the refrigerant outlet port (PO2) into the first flow path (F1), and is configured to return a refrigerant that has passed to through the condenser (20) to the compressor (10). A first expansion valve (71), a liquid receiver (73) and a second expansion valve (72) are arranged in the second flow path (F2) in order from a branch point of the second flow path ( F2) from the first one. flow path (F1) . The control device (100) controls the compressor (10), the first expansion valve (71) and the second expansion valve (72). The control device (100) provides a notification regarding a refrigerant shortage if the period during which the opening of the second expansion valve (72) is at an upper opening limit exceeds a determining time. (Automatic translation with Google Translate, without legal value)

Description

DESCRIPTION

Outdoor unit and refrigeration cycle apparatus

Technical field

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

Background of the technique

In a refrigeration cycle apparatus, excess or shortage of the amount of refrigerant causes degradation of the capacity of a refrigeration apparatus and damage to its constituent devices. Document WO 2017/199391 (PTL 1) discloses a refrigeration cycle apparatus that prevents a failure of a compressor by detecting a shortage of refrigerant.

Appointment list

Patent bibliography

PTL 1: WO 2017/199391

Summary of the invention

technical problem

A refrigeration cycle apparatus is known that has an injection flow path that decompresses a portion of the liquid refrigerant leaving a condenser, reduces its temperature, and returns it to a compressor. The refrigerant in the compressor can be cooled by the injection flow path. In addition to a common refrigeration apparatus, WO 2017/199391 (PTL 1) also discloses a refrigeration apparatus having an injection flow path, and the shortage of refrigerant is detected before the compressor fails.

Generally, when the sealed refrigerant in a refrigerant circuit becomes insufficient due to a shortage of filling quantity, leakage, or the like, the temperature of the refrigerant discharged from a compressor exceeds the target temperature, for example, causing a reduction in efficiency. of a refrigeration cycle apparatus. Accordingly, even at a stage where refrigerant shortage does not cause compressor failure or the like, it is desirable to detect refrigerant shortage progressing due to refrigerant leakage or the like at the earliest possible stage.

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.

Solution to the problem

The present invention relates to an outdoor unit of a refrigeration cycle apparatus as defined in claim 1, the outdoor unit being connectable to a charging device including an expansion device and an evaporator. The outdoor unit includes a refrigerant outlet port and a refrigerant inlet port for connecting to the charging device, a first flow path, a compressor, a condenser, a second flow path, a first expansion valve, a receiver , a second expansion valve and a controller. The first flow path, which is a flow path from the refrigerant inlet port to the refrigerant outlet port, is configured to form, together with the charging device, a circulation flow path through which coolant circulates. The compressor and condenser are arranged in the first flow path in order from the refrigerant inlet port to the refrigerant outlet port. The second flow path is configured to branch from a portion of the first flow path between the condenser and the refrigerant outlet port, and return, to the compressor, the refrigerant that has passed through the condenser. The first expansion valve, the receiver and the second expansion valve are arranged in the second flow path in order from a branch point where the second flow path branches from the first flow path. The controller is configured to control the compressor and the first and second expansion valves. The controller is configured to notify that the refrigerant is insufficient when a period of time during which the opening degree of the second expansion valve is at an upper limit exceeds a determining time period.

Advantageous effects of the invention

In accordance with the outdoor unit and the refrigeration cycle apparatus including the same hereof Invention, when the refrigerant becomes insufficient due to refrigerant leakage or the like, the refrigerant shortage can be detected at an early stage.

Brief description of the drawings

Figure 1 is a general configuration diagram of a refrigeration cycle apparatus according to a first embodiment of the present invention.

Figure 2 is a flow chart to illustrate the control of a first expansion valve 71.

Figure 3 is a flow chart to illustrate the control of a second expansion valve 72.

Figure 4 is a graph showing the relationship between a degree of progression of refrigerant shortage and the opening degrees of the expansion valves of an outdoor unit when a refrigerant leak occurs.

Figure 5 is a general configuration diagram of a refrigeration cycle apparatus according to a second embodiment.

Description of the achievements

Preferred embodiments of the present invention will now be described in detail with reference to the drawings. Although a plurality of embodiments will be described below, it is originally intended that at the time of filing of the present application, the features described in the embodiments will be suitably combined. It should be noted that identical or corresponding parts in the drawings will be designated with the same reference characters, and the description thereof will not be repeated.

First realization

Figure 1 is a general configuration diagram of a refrigeration cycle apparatus according to a first embodiment. It should be noted that Figure 1 functionally shows the connection relationship and arrangement configuration of devices in the refrigeration cycle apparatus, and does not necessarily show an arrangement in physical space.

Referring to Figure 1, a refrigeration cycle apparatus 1 includes an outdoor unit 2, a charging device 3 and pipes 84 and 88. The outdoor unit 2 has a PO refrigerant outlet port ₂ and a PO refrigerant inlet port. refrigerant PI2 to connect to charging device 3. Charging device 3 has a PO refrigerant outlet port ₃ and a PI3 refrigerant inlet port to connect to outdoor unit 2. Pipe 84 connects the refrigerant outlet port PO ₂ of outdoor unit 2 to refrigerant inlet port PI3 of charging device 3. Pipe 88 connects refrigerant outlet port PO ₃ of charging device 3 to refrigerant inlet port PI2 of outdoor unit 2.

The outdoor unit 2 of the refrigeration cycle apparatus 1 can be connected to the charging 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 charging device 3 includes an expansion valve 50 which is an expansion device, an evaporator 60 and pipes 85, 86 and 87. The evaporator 60 is configured to perform heat exchange between air and 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 expansion valve 50 is, for example, a temperature-controlled expansion valve independently of the outdoor unit 2. It should be noted that the expansion valve 50 may be an electronic expansion valve that can decompress the refrigerant.

The compressor 10 compresses the refrigerant sucked from the pipe 89 and discharges the compressed refrigerant to the pipe 80. The compressor 10 can arbitrarily change a drive frequency by controlling the inverter. Furthermore, the compressor 10 is provided with an intermediate pressure port G3 and allows the refrigerant of the intermediate pressure port G3 to flow to an intermediate portion 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, the circulation amount of the refrigerant is adjusted, and the capacity of the cooling apparatus can be adjusted. refrigeration cycle 1. As a compressor 10, various types of compressors can be adopted, and for example, a propeller type compressor, a rotary type compressor, a screw type compressor or the like.

The condenser 20 is configured such that the high temperature, high pressure gas refrigerant discharged from the compressor 10 performs heat exchange with the outside air (heat dissipation). Through this heat exchange, the refrigerant gas condenses and transforms into a liquid phase. The refrigerant discharged from the compressor 10 to the pipe 80 is condensed and liquefied in the condenser 20 and flows to the pipe 81. The fan 22 for blowing outside air is attached 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, it can be adjusted a refrigerant pressure on a discharge side of the compressor 10 (a high pressure side pressure).

The outdoor unit 2 includes a first flow path F1 from the refrigerant inlet port PI2 to the refrigerant outlet port PO2 through the compressor 10 and the condenser 20. The first flow path F1 is formed, together with a flow in which the expansion valve 50 and the evaporator 60 of the charging device 3 are arranged, a circulation flow path through which the refrigerant circulates. Below, this circulation flow path will also be called the "main refrigerant circuit" of a refrigeration cycle.

The outdoor unit 2 further includes a second flow path F2 that includes pipes 91, 92, 93 and 94 configured to cause the refrigerant to flow from a portion of the circulation flow path between an outlet of the condenser 20 and the port of refrigerant outlet PO ₂ to the intermediate pressure port G3 of the compressor 10. Next, the second flow path F2 that branches from the main refrigerant circuit and delivers the refrigerant to the compressor 10 will also be called "injection flow path".

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

The pipe 91 is a pipe that branches from the main refrigerant circuit and causes the refrigerant to flow to the receiver 73. The first expansion valve 71 is an electronic expansion valve that can decrease the pressure of the refrigerant in a high pressure portion 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 circulation amount of the refrigerant in the main refrigerant circuit. The pipe 93 connected to the upper portion of the receiver 73 and the pipe 94 connected to the lower portion of the receiver 73 are pipes for taking out the separated refrigerant into refrigerant gas and refrigerant liquid inside the receiver 73, in a separated state. The second expansion valve 72 is provided in the pipe 94. The second expansion valve 72 adjusts the amount of liquid refrigerant to be expelled from the pipe 94, and therefore can adjust the amount of 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 pipe 81 which is a liquid pipe. This is because since the receiver 73 generally includes the refrigerant gas in it and the temperature of the refrigerant reaches a saturation temperature, it is not possible to ensure subcooling if the receiver 73 is arranged in the pipe 81.

The outdoor unit 2 further includes pressure sensors 110, 111 and 112, temperature sensors 120 and 121, and controller 100 configured to control the compressor 10, the first expansion valve 71 and the second expansion 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 pressure PH of the refrigerant discharged from the compressor 10 and outputs a detection value thereof to the controller 100. The pressure sensor 112 detects a pressure P1 of the refrigerant leaving the condenser 20 and outputs a detection value thereof to the controller 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 controller 100. The temperature sensor 121 detects a temperature T1 of the refrigerant in the pipe 81 at the outlet of the condenser 20 and outputs a detection value of the same to controller 100.

In the present embodiment, the second flow path F2 controls the temperature TH of the refrigerant discharged from the compressor 10 by causing the refrigerant to decompress and have a lower temperature to flow to the compressor 10. Additionally, the amount of refrigerant in the Main refrigerant circuit can be adjusted by means of receiver 73 placed in the second flow path F2.

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 of 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 software but also by dedicated hardware (electronic circuits).

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

Figure 2 is a flow chart to illustrate the control of the first 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 controller 100 increases the opening degree of the first expansion valve 71 (S22). Thus, the refrigerant flowing to the intermediate pressure port G3 through the receiver 73 increases and therefore 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 controller 100 decreases the opening degree of the first expansion valve 71 (S24). Thus, the refrigerant flowing to the intermediate pressure port G3 through the receiver 73 decreases and therefore the temperature TH increases.

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

In this way, the controller 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.

Furthermore, in normal operation, the controller 100 controls the feedback of the second expansion valve 72 so that the temperature T1 of the refrigerant at the outlet of the condenser 20 coincides with a target temperature, to ensure subcooling SC of the refrigerant at the outlet of the condenser 20. On this occasion, in the first embodiment, the detection of refrigerant shortage is also carried out simultaneously.

Figure 3 is a flow chart to illustrate the control of the second expansion valve 72. In steps S31 and S33, the controller 100 calculates the subcooling SC of the refrigerant in the outlet portion of the condenser 20 based on the temperature T1 and the pressure in condenser 20 (approximated by PH). Specifically, the controller 100 calculates the subcooling SC by subtracting the temperature T1 from the saturation temperature of the refrigerant corresponding to the pressure PH. It should be noted that a conversion table is previously stored in the memory 104 of the controller 100 to obtain the saturation temperature of the refrigerant corresponding to each pressure. The controller 100 then compares the calculated SC subcooling with a target value. This target value is 5 K (kelvin), for example. When the subcooling SC is greater than the target value (YES in S31), the controller 100 decreases the opening degree of the second expansion valve 72 (S32). Thus, the amount of liquid refrigerant to be expelled from the receiver 73 decreases and the amount of liquid refrigerant inside the receiver 73 increases and, therefore, the amount of refrigerant circulating through the main refrigerant circuit decreases. Consequently, the temperature T1 of the coolant increases and, therefore, the subcooling SC decreases.

On the other hand, when the 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), in step S34, the controller 100 determines whether the opening degree of the second valve expansion valve 72 is fully open or not. In this case, fully open means that the opening degree of the second expansion valve 72 has an upper limit value.

When the opening degree of the second expansion valve 72 is not fully open (NO at S34), the controller 100 increases the opening degree of the second expansion valve 72 (S35). Thus, the amount of liquid refrigerant to be expelled from the receiver 73 increases and the amount of liquid refrigerant stored in the receiver 73 decreases and, therefore, the amount of refrigerant circulating through the main refrigerant circuit increases. Consequently, the temperature T1 of the coolant decreases and, therefore, the subcooling SC increases.

On the other hand, when the opening degree of the second expansion valve 72 is fully open (YES at S34), in step S36, the controller 100 determines whether the state in which the second expansion valve 72 is fully open continues. or not during a determination period of time.

When the state in which the second expansion valve 72 is fully open does not continue during the determining time period (NO in S36), the controller 100 maintains the opening degree of the second expansion valve 72 in the fully open state .

On the other hand, when the state in which the second expansion valve 72 is fully open continues during the determination time period (YES in S36), in step S37, the controller 100 causes a notification device 101 to issue a alarm indicating that the refrigerant is insufficient. The notification device 101 is, for example, a display device such as a liquid crystal display, a lamp alarm, or similar, and may be a device that transmits an alarm signal to an external device through a communication line.

After performing the process in any of the steps S32, S35 and S37, the controller 100 takes the process to the step S38. Furthermore, when the subcooling SC of the refrigerant at the outlet of the condenser 20 is equal to the target value (NO at S31 and NO at S33), the controller 100 advances the processing to step S38 while maintaining the current degree of opening. In these cases, processing is temporarily returned to a main routine, and then the processing in the flowchart of Figure 3 is performed repeatedly at fixed time intervals.

Figure 4 is a graph showing the relationship between a degree of progression of refrigerant shortage and the opening degrees of the expansion valves of the outdoor unit when a refrigerant leak occurs. The degree of refrigerant shortage increases as the advance degree from D0 to D3 increases.

When the advance degree is D0 to D1, the amount of refrigerant is still not insufficient and liquid refrigerant is present in the receiver 73. In this phase, the temperature of the refrigerant discharged from the compressor 10 is appropriately controlled by increasing the opening degree of the second expansion valve 72 until it opens completely. However, the subcooling SC of the refrigerant in the outlet portion of the condenser 20 gradually decreases, and the subcooling SC is zero when the progress degree is D1.

When the advance degree is D1 to D2, the temperature of the refrigerant discharged from the compressor 10 is still correctly controlled, although the subcooling SC of the refrigerant in the outlet portion of the condenser 20 is zero. However, the amount of liquid refrigerant in the receiver 73 decreases, and the liquid refrigerant is not present in the receiver 73 when the advance degree is D2. In this phase, the opening degree of the second expansion valve 72 is completely open.

When the advance degree is D2 to D3, the subcooling SC of the refrigerant in the outlet portion of the condenser 20 is zero, and the liquid refrigerant is not present in the receiver 73. In this phase, the opening degree of the first valve Expansion pressure 71 increases to increase the amount of coolant flowing into the injection flow path. However, the temperature TH of the refrigerant discharged from the compressor 10 becomes higher than the optimal state. Next, when the advance degree is D3, the opening degree of the first expansion valve 71 is completely open.

As shown in Figure 4, in a process where refrigerant shortage occurs, both the first expansion chamber valve 71 and the second expansion chamber valve 72 are fully opened. Since the second expansion valve 72 is fully opened at an earlier stage, the shortage of refrigerant can be detected at an earlier stage when the shortage of refrigerant is determined based on the opening degree of the second expansion valve 72. Herein embodiment, the refrigerant is determined to be insufficient when a period of time during which the opening degree of the second expansion valve 72 is fully open reaches the determination time period. Consequently, a user can be notified of refrigerant shortage at an early stage.

Second realization

The first embodiment has described the case using the refrigerant for which the subcooling SC can be calculated from the temperature T1 and the pressure PH, that is, the refrigerant used with the pressure in the condenser less than a critical pressure. In recent years, the adoption of natural refrigerant with a low global warming potential has been considered, and refrigerant used with a condenser pressure greater than or equal to the critical pressure, such as CO ² , can be adopted. A second embodiment will describe the detection of refrigerant shortage in a case where said refrigerant is adopted.

Figure 5 is a general configuration diagram of a refrigeration cycle apparatus according to the second embodiment. It should be noted that Figure 5 functionally shows the connection relationship and arrangement configuration of devices in the refrigeration cycle apparatus, and does not necessarily show an arrangement in physical space.

Referring to Figure 5, a refrigeration cycle apparatus 1A includes an outdoor unit 2A, charging device 3 and pipes 84 and 88. Since the charging device 3 and pipes 84 and 88 are the same as those of the first embodiment, the description in this regard will not be repeated.

The outdoor unit 2A includes a temperature sensor 123 instead of the pressure sensor 112 and a controller 100A instead of the controller 100, in the configuration of the outdoor unit 2 shown in Figure 1. Since other components of the outdoor unit 2A are the same as those of outdoor unit 2, the description in this regard will not be repeated.

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

Controller 100A includes CPU 102, memory 104, input/output buffers (not shown) for input/output of 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 100A. According to these programs, the controller 100A performs control of the devices in the outdoor unit 2A. This control can be processed not only by software but also by dedicated hardware (electronic circuits).

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

Furthermore, in normal operation, the controller 100A feeds back to the controls of the second expansion valve 72 so that the temperature T1 of the refrigerant at the outlet of the condenser 20 coincides with a target temperature, to ensure subcooling SC of the refrigerant at the outlet of the condenser 20. On this occasion, in the second embodiment, the detection of refrigerant shortage is also carried out simultaneously.

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 called a condenser 20. Furthermore, herein, for ease of description, a quantity of Decrease of a reference temperature of the coolant in the supercritical state will also be called subcooling. In the second embodiment, the reference temperature is set to TA+a, where TA is the outdoor air temperature measured by the temperature sensor 123, and the decrease amount has a target value of 5 K (kelvin), for example .

Also in the second embodiment, the shortage of refrigerant can be detected at an early stage by processing the flow chart shown in Figure 3, calculating the subcooling SC as a difference between the temperature TA+a and the temperature T1.

In the case that the pressure in the condenser 20 may exceed the critical pressure as in the second embodiment, if the receiver 73 is provided in an intermediate pressure portion, it becomes possible to store the intermediate pressure liquid refrigerant inside the receiver 73 even when the pressure in the high pressure portion of the main refrigerant circuit is high and the refrigerant is in a supercritical state. In this way, 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 thinning the vessel.

The outdoor units and refrigeration cycle apparatuses of the first and second embodiments described above will be summarized with reference to the drawings again.

The present invention relates to the outdoor unit 2 of the refrigeration cycle apparatus 1 and the outdoor unit 2A of the refrigeration cycle apparatus 1A, each outdoor unit being connectable to the charging device 3 including the expansion valve 50, which is a expansion device, and the evaporator 60. The outdoor unit 2 shown in Figure 1 and the outdoor unit 2A shown in Figure 5 include a refrigerant outlet port PO ₂ and a refrigerant inlet port PI2 for connect to charging device 3, first flow path F1, compressor 10, condenser 20, second flow path F2, first expansion valve 71, receiver 73, second expansion valve 72 and controller 100 or 100A. The first flow path F1, which is a flow path from the refrigerant inlet port PI2 to the refrigerant outlet port PO ₂ , is configured to form, together with the charging device 3, a circulation flow path at through which the refrigerant circulates. The compressor 10 and the condenser 20 are arranged in the first flow path F1 in order from the refrigerant inlet port PI2 to the refrigerant outlet port PO ₂ . The second flow path F2 is configured to branch from a portion of the first flow path F1 between the condenser 20 and the refrigerant outlet port PO ₂ , and to return, to a compressor 10, the refrigerant that has passed through the condenser 20. The first expansion valve 71, the receiver 73 and the second expansion valve 72 are arranged in the second flow path F2 in order from a branch point where the second flow path F2 branches from the first flow path flow F1. The controllers 100 and 100A are configured to control the compressor 10 and the first and second expansion valves 71 and 72. The controllers 100 and 100a are configured to notify that the refrigerant is insufficient when a period of time during which the degree of opening of the second expansion valve 72 is at an upper limit exceeds a determining time period.

By detecting the shortage of the coolant as described above, the shortage of coolant can be detected at an early stage in the configuration in which the receiver 73 is arranged in the injection flow path, and capacity degradation can be avoided. of the refrigeration cycle appliance and continued leakage of refrigerant.

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

More preferably, the outdoor unit 2 shown in Figure 1 further includes a pressure sensor 111 configured to detect the PH pressure of the refrigerant in the refrigerant outlet portion of the condenser 20 in the first flow path F1. When the time period during which the opening degree of the second expansion valve 72 is at the upper limit exceeds the determination time period, and the subcooling SC of the refrigerant calculated based on the output of the first temperature sensor 121 and the output of the pressure sensor 111 is not equal to a target value, the controller 100 determines that the refrigerant is insufficient.

More preferably, the refrigerant used in the configuration shown in Figure 1 is a refrigerant used with a pressure in the condenser 20 less than a critical pressure.

More preferably, the outdoor unit 2A shown in Figure 5 further includes a second temperature sensor 123 configured to detect the temperature TA of the outdoor air to be supplied to the condenser 20. When the period of time during which the degree of opening of the second expansion valve 72 is at the upper limit exceeds the determination time period, and the difference between the detection temperature of the first temperature sensor 121 and the detection temperature of the second temperature sensor 123 is less than a value determination, the controller 100A determines that the refrigerant is insufficient.

More preferably, the refrigerant used in the configuration shown in Figure 5 is carbon dioxide used with a pressure in the condenser 20 that is greater than or equal to the critical pressure.

In another aspect, the present invention relates to a refrigeration cycle apparatus including the outdoor unit according to any of the above descriptions and the charging device.

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

List of reference signs

1, 1A: refrigeration cycle apparatus; 2, 2A: outdoor unit; 3: charging device; 10: compressor; 20: capacitor; 22: fan; 50: expansion valve; 60: evaporator; 70: flow limiting device; 71: first expansion valve; 72: second expansion valve; 73: receiver; 80, 81,84, 85, 88, 89, 91, 92, 93, 94: pipe; 100, 100A: controller; 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: coolant inlet port; PO ₂ , PO ₃ : refrigerant outlet port.

Claims (7)

1. An outdoor unit (2) of a refrigeration cycle apparatus, the outdoor unit (2) being connectable to a charging device (3) that includes an expansion device (50) and an evaporator (60), comprising the outdoor unit: a refrigerant outlet port and a refrigerant inlet port for connecting to the charging device; a first flow path (F1), which is a flow path from the refrigerant inlet port to the refrigerant outlet port, the first flow path being configured to form, together with the charging device, a flow path circulation flow through which the coolant circulates; a compressor (10) and a condenser (20) arranged in the first flow path (F1) in order from the refrigerant inlet port (PI2) to the refrigerant outlet port (PO2); a second flow path (F2) configured to branch from a portion of the first flow path (F1) between the condenser (20) and the refrigerant outlet port (PO2), and to return, to the compressor (10), the refrigerant that has passed through the condenser (10); a first expansion valve (71), a receiver (73) and a second expansion valve (72) arranged in the second flow path (F2) in order from a bifurcation point where the second flow path (F2) is branches from the first flow path (F1); and a controller (100) configured to control the compressor (10) and the first and second expansion valves (71, 72), the controller (100) being configured to notify that the refrigerant is insufficient when a period of time for which a opening degree of the second expansion valve (72) is at an upper limit exceeds a determining time period. 2. The outdoor unit (2, 2A) according to claim 1, further comprising a first temperature sensor (121) configured to detect a temperature of the refrigerant in a refrigerant outlet portion of the condenser (20) in the first flow path (F1), in which The controller (100, 100A) is configured to control the opening degree of the second expansion valve (72) according to an output of the first temperature sensor (121). 3. The outdoor unit (2) according to claim 2, further comprising a pressure sensor (111) configured to detect a pressure of the refrigerant in the refrigerant outlet portion of the condenser (20) in the first flow path (F1), in which when the time period during which the opening degree of the second expansion valve (72) is at the upper limit exceeds the determination time period, and a subcooling of the refrigerant calculated based on the output of the first temperature sensor (121) and an output of the pressure sensor (111) does not equal a target value, the controller (100) determines that the refrigerant is insufficient. 4. The outdoor unit according to claim 3, wherein the refrigerant is a used refrigerant with a pressure in the condenser (20) being less than a critical pressure. 5. The outdoor unit (2A) according to claim 2, further comprising a second temperature sensor (123) configured to detect a temperature of the outdoor air to be supplied to the condenser (20), wherein when the time period during which the opening degree of the second expansion valve (72) is at the upper limit exceeds the determination time period, and a difference between a detection temperature of the first temperature sensor (121) and a detection temperature of the second temperature sensor (123) is smaller than a determination value, the controller (100A) determines that the refrigerant is insufficient. 6. The outdoor unit according to claim 5, wherein the refrigerant is carbon dioxide used with a pressure in the condenser (20) that is greater than or equal to a critical pressure. 7. A refrigeration cycle apparatus comprising: the outdoor unit (2, 2A) according to any one of claims 1 to 6; and the charging device (3).