WO2021192292A1 - Outdoor unit and refrigeration cycle device - Google Patents

Abstract

In the present invention, a refrigeration cycle device (1) is provided with a load device (3) and an outdoor unit (2). The outdoor unit (2) comprises a compressor (10), a condenser (20), a heat exchanger (30), a second expansion valve (40), an injection flow path (101) via which a refrigerant is caused to flow from piping (81) between the outlet of the condenser (20) and the inlet of a first passage (H1), a control device (100), and a notification device (150). The injection flow path (101) is provided with a first refrigerant flow path (91-94), a second refrigerant flow path (96), a liquid receiver (73), a third expansion valve (71), and a flow rate adjustment valve (72). The control device (100) determines whether there is a shortage of the refrigerant on the basis of the opening degree of the flow rate adjustment valve (72) if the discharge pressure of the compressor (10) is in a supercritical state in which the critical pressure of the refrigerant is exceeded.

Description

Outdoor unit and refrigeration cycle device

This disclosure relates to an outdoor unit and a refrigeration cycle device.

Japanese Patent Application Laid-Open No. 2014-119221 (Patent Document 1) describes a circulation flow path (main refrigerant circuit) in which a refrigerant circulates in a compressor, a condenser, an expansion valve, and an evaporator, and an injection flow branching from the circulation flow path. A refrigeration system with a road is disclosed. In this freezer, the discharge temperature of the compressor can be lowered by merging a part of the refrigerant flowing from the condenser toward the expansion valve with the refrigerant at the intermediate pressure of the compressor using the injection flow path. .. Further, in this freezing device, a liquid receiver is provided in the middle of the injection flow path, and the amount of refrigerant stored in the liquid receiver can be adjusted by the expansion valve of the outdoor unit.

Further, this refrigerating apparatus is provided with an economizer (heat exchanger) that exchanges heat between the refrigerant flowing in the circulation flow path from the condenser toward the expansion valve and the refrigerant flowing in the injection flow path. As a result, the refrigerant flowing from the condenser toward the expansion valve is cooled by the refrigerant flowing through the injection flow path, so that supercooling is ensured.

Japanese Unexamined Patent Publication No. 2014-119221

As described above, the amount of refrigerant gas and the amount of refrigerant liquid supplied from the receiver to the economizer are contained in the injection flow path provided with the receiver and the refrigeration cycle device provided with the heat exchanger (economizer) described above. Some have a flow control valve to adjust.

In the refrigeration cycle device provided with the above flow rate adjusting valve, the amount of refrigerant flowing from the injection flow path to the circulation flow path can be adjusted by adjusting the opening degree of the flow rate adjusting valve. Further, in the refrigeration cycle apparatus provided with the flow rate adjusting valve, if the temperature efficiency (heat exchange amount) of the heat exchanger is low even though the opening degree of the flow rate adjusting valve is increased, circulation occurs. It can be determined that the refrigerant filled in the entire refrigerant circuit including the flow path and the injection flow path is insufficient.

However, when a refrigerant that can be in a supercritical state is used, the refrigerant may be operated in the supercritical state. When operating in a supercritical state, the relationship between the saturation temperature and the outside air temperature changes, so it is difficult to determine the presence or absence of refrigerant shortage using the temperature efficiency of the heat exchanger described above.

The present disclosure has been made to solve the above-mentioned problems, and an object of the present invention is to provide a refrigerant in a refrigerant circuit even under operating conditions in a supercritical state in a refrigeration cycle apparatus in which a refrigerant capable of being in a supercritical state is used. It is to make it possible to determine whether or not there is a shortage.

The outdoor unit according to the present disclosure is an outdoor unit of a refrigeration cycle device configured to be connected to a load device including a first expansion valve and an evaporator. This outdoor unit has a compressor having a suction port, a discharge port and an intermediate pressure port, a condenser, a first passage and a second passage, and a refrigerant flowing through the first passage and a refrigerant flowing through the second passage. It is provided with a heat exchanger for exchanging heat between the two, and a second expansion valve. The flow path from the compressor to the condenser, the first passage of the heat exchanger, and the second expansion valve forms a circulation flow path through which the refrigerant circulates together with the load device. The outdoor unit further includes an injection flow path for flowing the refrigerant from the branch portion between the outlet of the condenser and the inlet of the first passage in the circulation flow path to the compressor. The injection flow path includes a first refrigerant flow path in which the refrigerant flows from the branch portion to the inlet of the second passage, and a second refrigerant flow path in which the refrigerant flows from the outlet of the second passage to the suction port or the intermediate pressure port of the compressor. , The receiver arranged in the first refrigerant flow path, the third expansion valve arranged in the portion between the branch portion and the inlet of the liquid receiver in the first refrigerant flow path, and the first refrigerant flow path. A flow control valve arranged in a portion between the outlet of the receiver and the inlet of the second passage is provided. The outdoor unit further includes a control device that controls a compressor, a second expansion valve, a third expansion valve, and a flow rate adjusting valve, and a notification device that notifies the user of information from the control device. When the discharge pressure of the compressor is in a supercritical state exceeding the critical pressure of the refrigerant, the control device determines whether the refrigerant contained in the circulation flow path and the injection flow path is insufficient based on the opening degree of the flow rate adjusting valve. Is determined.

According to the present disclosure, in a refrigeration cycle apparatus in which a refrigerant that can be in a supercritical state is used, it is possible to determine whether or not there is a refrigerant shortage in the refrigerant circuit even under operating conditions in the supercritical state.

It is an overall block diagram of the refrigeration cycle apparatus. It is a figure which showed the various sensors and the control device arranged in the refrigeration cycle apparatus 1. It is a Moriel diagram which shows the aspect of the refrigerant change in a normal state schematically. It is a Moriel diagram which shows the aspect of the refrigerant change in a supercritical state schematically. It is a flowchart which shows an example of the processing procedure when the control device performs the refrigerant amount adjustment and the refrigerant shortage detection.

Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings. Hereinafter, a plurality of embodiments will be described, but it is planned from the beginning of the application that the configurations described in the respective embodiments are appropriately combined. The same or corresponding parts in the drawings are designated by the same reference numerals, and the description thereof will not be repeated.

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

With reference to FIG. 1, the refrigeration cycle device 1 includes an outdoor unit 2, a load device 3, and extension pipes 84 and 88.

The outdoor unit 2 is an outdoor unit of the refrigeration cycle device 1 configured to be connected to the 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, a heat exchanger (economizer) 30, a second expansion valve 40, and piping. It includes 80 to 83 and 89. The heat exchanger 30 has a first passage H1 and a second passage H2, and is configured to exchange heat between the refrigerant flowing through the first passage H1 and the refrigerant flowing through the second passage H2.

The load device 3 includes a first expansion valve 50, an evaporator 60, and pipes 85, 86, 87. The evaporator 60 exchanges heat between air and the refrigerant. In the refrigeration cycle device 1, the evaporator 60 evaporates the refrigerant by endothermic heat from the air in the cooling target space. The first expansion valve 50 is an electronic expansion valve capable of reducing the pressure of the refrigerant. The first expansion valve 50 may be, for example, a temperature expansion valve that is controlled independently of the outdoor unit 2.

The compressor 10 compresses the refrigerant sucked from the pipe 89 and the pipe 96 and discharges it to the pipe 80. The drive frequency of the compressor 10 can be arbitrarily changed by inverter control. Further, the compressor 10 is provided with an intermediate pressure port G3, so that the refrigerant from the intermediate pressure port G3 can flow into a portion in the middle of the compression process. The compressor 10 is configured to adjust the rotation speed according to a control signal from the control device 100 (see FIG. 2). By adjusting the rotation 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 of compressors 10 can be adopted, and for example, scroll type, rotary type, screw type and the like can be adopted.

The condenser 20 is configured such that a high-temperature and high-pressure gas refrigerant discharged from the compressor 10 exchanges heat (heat dissipation) with the outside air. By this heat exchange, the refrigerant is condensed and changed to a liquid phase. The refrigerant discharged from the compressor 10 to the pipe 80 is condensed and liquefied in the condenser 20 and flows out to the pipe 81. A fan 22 for sending outside air is attached to the condenser 20 in order to improve the efficiency of heat exchange. The fan 22 supplies the condenser 20 with outside air through which the refrigerant exchanges heat in the condenser 20. By adjusting the rotation speed of the fan 22, the refrigerant pressure (high pressure side pressure) on the discharge side of the compressor 10 can be adjusted. The second expansion valve 40 is an electronic expansion valve capable of reducing the pressure of the refrigerant discharged from the condenser 20.

The flow path from the compressor 10 to the condenser 20, the first passage H1 of the heat exchanger 30, and the second expansion valve 40 is together with the flow path in which the first expansion valve 50 and the evaporator 60 of the load device 3 are arranged. , Form a circulation flow path through which the refrigerant circulates. Hereinafter, this circulation flow path is also referred to as a "main refrigerant circuit" of the refrigeration cycle.

The outdoor unit 2 further includes an "injection flow path 101" that branches from the main refrigerant circuit and sends the refrigerant to the compressor 10 via the second passage H2. The injection flow path 101 includes a "first refrigerant flow path" (pipes 91 to 94) for flowing a refrigerant from the pipe 81, which is a high-pressure portion of the main refrigerant circuit, to the inlet of the second passage H2, and an outlet of the second passage H2. Includes a "second refrigerant flow path" (pipe 96) that allows the refrigerant to flow through the intermediate pressure port G3 of the compressor 10.

An on-off valve 75 is arranged in the second refrigerant flow path (pipe 96) of the injection flow path 101. It is possible to adjust whether or not the refrigerant is supplied to the intermediate pressure port G3 of the compressor 10 by the on-off valve 75. Although not shown in FIG. 1, one of the suction port G1 and the intermediate pressure port G3 is used as the destination of the refrigerant that is arranged in the second refrigerant flow path (pipe 96) and flows out from the outlet of the second passage H2. A selectable flow path switching device may be further provided.

A receiver (receiver) 73 for storing the refrigerant and a third expansion valve 71 are arranged in the first refrigerant flow path of the injection flow path 101. The inlet of the liquid receiver 73 is connected to the pipe 81 (that is, the portion of the circulation flow path between the outlet of the condenser 20 and the inlet of the first passage H1) by the pipes 91 and 92. The third expansion valve 71 is arranged in the middle of the pipes 91 and 92.

A flow rate adjusting valve 72 and a gas vent passage 95 are further arranged in the first refrigerant flow path of the injection flow path 101. The flow rate adjusting valve 72 is an expansion valve arranged between the pipe 93 at the outlet of the liquid receiver 73 and the pipe 94 leading to the second passage H2. The gas vent passage 95 connects the gas discharge port of the liquid receiver 73 and the second passage H2, and discharges the refrigerant gas in the liquid receiver 73.

The pipe 91 is a pipe that branches from the pipe 81, which is a high-pressure portion of the main refrigerant circuit, and allows the refrigerant to flow into the liquid receiver 73. The third expansion valve 71 is an electronic expansion valve capable of reducing the refrigerant in the pipe 81, which is a high-pressure portion of the main refrigerant circuit, to an intermediate pressure. The liquid receiver 73 is a container capable of separating the gas and liquid in the container from the decompressed and two-phase refrigerant, storing the refrigerant, and adjusting the amount of the refrigerant in the main refrigerant circuit. The gas vent passage 95 connected to the upper part of the receiver 73 and the pipe 93 connected to the lower part of the receiver 73 are in a state where the refrigerant separated into the gas refrigerant and the liquid refrigerant is separated in the receiver 73. It is a pipe for taking out. The flow rate adjusting valve 72 can adjust the amount of refrigerant in the liquid receiver 73 by adjusting the amount of circulation of the liquid refrigerant discharged from the pipe 93.

By providing the liquid receiver 73 in the injection flow path 101 in this way, it becomes easy to secure the degree of supercooling in the pipes 82 and 83 which are the liquid pipes of the main refrigerant circuit. Since the receiver 73 generally contains a gas refrigerant, the refrigerant temperature in the receiver 73 becomes a saturation temperature. However, if the receiver 73 is arranged in the pipe 82 which is the liquid pipe of the main refrigerant circuit, the pipe 82 This is because the temperature of the refrigerant inside is less likely to drop below the saturation temperature, and the degree of supercooling cannot be ensured.

The heat exchanger 30 exchanges heat between the refrigerant flowing through the first passage H1 which is a part of the main refrigerant circuit and the refrigerant flowing through the second passage H2 which is a part of the injection flow path 101.

If the liquid receiver 73 is provided in the pipes 81 and 91, which are the high-pressure parts of the main refrigerant circuit, if the pressure in the pipes 81 and 91 is high and the refrigerant in the pipes 81 and 91 is in a supercritical state, the liquid receiver The liquid refrigerant cannot be stored in the 73, and the function of buffering the excess refrigerant amount by the receiver 73 is lost. On the other hand, in the present embodiment, by providing the liquid receiver 73 in the pipe 92 which is the intermediate pressure portion lowered to the intermediate pressure by the third expansion valve 71, the amount of refrigerant even in the operation in the supercritical state Can be adjusted.

FIG. 2 is a diagram showing various sensors and a control device 100 arranged in the refrigeration cycle device 1 shown in FIG. With reference to FIG. 2, the outdoor unit 2 further includes pressure sensors 110 to 113, temperature sensors 120 to 125, a notification device 150, and a control device 100.

The pressure sensor 110 detects the pressure PL of the suction port portion of the compressor 10 and outputs the detected value to the control device 100. The pressure sensor 111 detects the discharge pressure PH of the compressor 10 and outputs the detected value to the control device 100. The pressure sensor 112 detects the pressure P1 of the pipe 83 at the outlet of the second expansion valve 40, and outputs the detected value to the control device 100. Further, the pressure sensor 113 detects the intermediate pressure PM of the pipe 92 after the third expansion valve 71, and outputs the detected value to the control device 100.

By providing the liquid pipe with the second expansion valve 40, the outdoor unit 2 can reduce the refrigerant pressure to or less than the design pressure (for example, 4 MPa) of the load device 3 and then deliver the refrigerant pressure to the load device 3. As a result, _{even if a refrigerant that utilizes supercritical fluid such as CO 2} is used, a general-purpose product having the same design pressure as the conventional one can be used as the load device 3.

The temperature sensor 120 detects the discharge temperature TH of the compressor 10 and outputs the detected value to the control device 100. The temperature sensor 121 detects the refrigerant temperature T1 of the pipe 81 at the outlet of the condenser 20, and outputs the detected value to the control device 100. The temperature sensor 122 detects the refrigerant temperature at the outlet of the first passage H1 on the cooled side of the heat exchanger 30 as the outlet temperature T2 of the heat exchanger 30, and outputs the detected value to the control device 100.

The temperature sensor 123 detects the ambient temperature of the outdoor unit 2 as the outside air temperature TA, and outputs the detected value to the control device 100. The temperature sensor 125 detects the temperature at the outlet of the second passage H2 of the heat exchanger 30 and outputs the detected value to the control device 100. The temperature sensor 124 detects the temperature TL of the suction pipe of the compressor 10 and outputs the detected value to the control device 100.

The notification device 150 is configured to notify the user of various information in response to a request from the control device 100. The notification device 150 may include at least one of a display device (for example, a touch panel display), a speaker (for example, a smart speaker), and a warning light.

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 / outputting various signals, and the like. Consists of including. The CPU 102 expands the program stored in the ROM into a RAM or the like and executes the program. The program stored in the ROM is a program in which the processing procedure of the control device 100 is described. The control device 100 executes control of each device in the outdoor unit 2 according to these programs. This control is not limited to software processing, but can also be processed by dedicated hardware (electronic circuit).

_{In this embodiment, CO 2} is used as the refrigerant used in the refrigerant circuit of the refrigeration cycle device 1. When CO ₂ is used as the refrigerant, depending on the operating conditions, the pressure of the refrigerant may be lower than the critical pressure (hereinafter, also referred to as "normal state"), or the pressure of the refrigerant may exceed the critical pressure (hereinafter, "normal state"). It may also be in a "supercritical state").

FIG. 3 is a Moriel diagram schematically showing the aspect of the refrigerant change in the normal state. FIG. 4 is a Moriel diagram schematically showing the aspect of the refrigerant change in the supercritical state. In FIGS. 3 and 4, the horizontal axis represents enthalpy (the amount of heat of the refrigerant), and the vertical axis represents the pressure of the refrigerant. The curve L1 shows a saturated liquid line, and the curve L2 shows a saturated vapor line.

As shown in FIG. 3, since the refrigerant pressure is lower than the critical pressure in the normal state, the refrigerant state straddles the saturated liquid line L1 when the enthalpy is lowered by the condenser 20. Therefore, supercooling can be defined.

On the other hand, as shown in FIG. 4, in the supercritical state, the refrigerant pressure exceeds the critical pressure, so that the refrigerant state does not straddle the saturated liquid line L1 when the enthalpy is lowered by the condenser 20. In this case, supercooling cannot be defined. In this specification, for the sake of simplicity, the amount of decrease in the refrigerant temperature in the supercritical state from the reference temperature is also referred to as the degree of supercooling.

[Pressure control in load device 3]
As described above, _{when CO 2} is used as the refrigerant, the supercritical region of the refrigerant may be used depending on the operating conditions. The control device 100 controls the compressor 10 and the second expansion valve 40 so that the refrigerant pressure in the load device 3 does not exceed the design pressure of the load device 3 even when the supercritical region of the refrigerant is used. At this time, in order to make the load device 3 shareable with the device normally used as the refrigerant, the control device 100 performs depressurization by the second expansion valve 40. Specifically, the control device 100 controls the second expansion valve 40 as follows.

The control device 100 feedback-controls the second expansion valve 40 so that the pressure P1 of the pipe 83 at the outlet of the second expansion valve 40 matches the target pressure. Specifically, when the pressure P1 is higher than the target pressure, the control device 100 reduces the opening degree of the second expansion valve 40. As a result, the amount of decompression by the second expansion valve 40 increases, so that the pressure P1 decreases. On the other hand, when the pressure P1 is lower than the target pressure, the control device 100 increases the opening degree of the second expansion valve 40. As a result, the amount of decompression by the second expansion valve 40 is reduced, so that the pressure P1 rises. If the pressure P1 is the target pressure, the control device 100 maintains the opening degree of the second expansion valve 40 in the current state.

Since the pressure P1 is controlled in this way, the refrigerant pressure in the load device 3 can be made lower than the design pressure of the conventional refrigerating device using a normal refrigerant (for example, R410A) that does not use the supercritical region, and the normal refrigerant can be used. Can be shared with conventional load devices that use.

[Control of the third expansion valve 71 and the flow rate adjusting valve 72]
In the refrigeration cycle apparatus 1 according to the present embodiment, by providing the injection flow path 101 branching from the main refrigerant circuit, the discharge temperature TH of the compressor 10 in the main refrigerant circuit is controlled, and the supercooling of the main refrigerant circuit is ensured. And it is possible to adjust the amount of refrigerant in the main refrigerant circuit. That is, the discharge temperature TH of the compressor 10 can be controlled by decompressing the refrigerant in the pipe 81 by the injection flow path 101 and causing the two-phase refrigerant to flow into the compressor 10. Further, by making a part of the injection flow path 101 into the second passage H2 of the heat exchanger 30, supercooling of the refrigerant in the main refrigerant circuit can be ensured. Further, the amount of refrigerant in the main refrigerant circuit can be adjusted by the liquid receiver 73 installed on the injection flow path 101.

The control device 100 according to the present embodiment operates each function of the injection flow path 101, such as controlling the discharge temperature TH in the main refrigerant circuit, ensuring supercooling of the main refrigerant circuit, and adjusting the amount of refrigerant in the main refrigerant circuit. The third expansion valve 71 and the flow rate adjusting valve 72 are controlled so that they can be exhibited under the conditions.

(Control of discharge temperature TH)
The control device 100 feedback-controls the opening degree of the third expansion valve 71 so that the discharge temperature TH of the compressor 10 matches the target temperature. Specifically, the control device 100 increases the opening degree of the third expansion valve 71 when the discharge temperature TH of the compressor 10 is higher than the target temperature. As a result, the amount of refrigerant flowing into the intermediate pressure port G3 via the liquid receiver 73 increases, so that the discharge temperature TH decreases.

On the other hand, when the discharge temperature TH of the compressor 10 is lower than the target temperature, the control device 100 reduces the opening degree of the third expansion valve 71. As a result, the amount of refrigerant flowing into the intermediate pressure port G3 via the liquid receiver 73 is reduced, so that the discharge temperature TH rises.

When the discharge temperature TH is the target temperature, the control device 100 maintains the opening degree of the third expansion valve 71 in the current state.

In this way, the control device 100 controls the opening degree of the third expansion valve 71 so that the discharge temperature TH of the compressor 10 approaches the target temperature.

(Adjusting the amount of refrigerant under normal conditions and detecting refrigerant shortage)
Under normal operating conditions, the control device 100 controls the flow rate adjusting valve 72 according to the temperature efficiency ε of the heat exchanger 30 in order to ensure supercooling. In the present embodiment, the temperature efficiency ε of the heat exchanger 30 is the temperature difference between the inlet and the outlet of the first passage H1 of the heat exchanger 30 with respect to the degree of superheat of the second passage H2 of the heat exchanger 30. = T1-T2) shall be represented.

Specifically, the control device 100 calculates the temperature efficiency ε of the heat exchanger 30 from the difference between the refrigerant temperature T1 at the outlet of the condenser 20 and the outlet temperature T2 of the heat exchanger 30. Then, when the calculated temperature efficiency ε is larger than the target value, it is considered that the amount of the refrigerant in the main refrigerant circuit is surplus, so that the control device 100 reduces the opening degree of the flow rate adjusting valve 72. As a result, the amount of liquid refrigerant passing through the receiver 73 decreases, and the amount of liquid refrigerant in the receiver 73 increases, so that the amount of refrigerant circulating in the main refrigerant circuit decreases. On the other hand, when the calculated temperature efficiency ε is smaller than the target value, it is considered that excess refrigerant is stored in the receiver 73 and the amount of refrigerant in the main refrigerant circuit is insufficient. , Increase the opening degree of the flow rate adjusting valve 72. As a result, the amount of liquid refrigerant in the receiver 73 is reduced, so that the amount of refrigerant circulating in the main refrigerant circuit is increased. When the temperature efficiency ε is the target value, the control device 100 maintains the opening degree of the flow rate adjusting valve 72 in the current state.

As described above, the control device 100 feedback-controls the opening degree of the flow rate adjusting valve 72 so that the temperature efficiency ε of the heat exchanger 30 becomes the target value under the operating conditions under the normal state. As a result, the temperature efficiency ε of the heat exchanger 30 is maintained at the target value, and the refrigerant is efficiently cooled by the heat exchanger 30. This ensures supercooling.

Instead of feedback-controlling the flow rate adjusting valve 72 so that the temperature efficiency ε of the heat exchanger 30 becomes the target value, the flow rate adjusting valve 72 so that the refrigerant temperature T1 at the outlet of the condenser 20 becomes the target temperature. May be feedback controlled. In this case, the target temperature of the refrigerant temperature T1 may be set to the temperature of the refrigerant temperature T1 when the temperature efficiency ε of the heat exchanger 30 becomes the target value.

As described above, under the operating conditions under the normal state, when the temperature efficiency ε of the heat exchanger 30 is smaller than the target value, the control device 100 increases the opening degree of the flow rate adjusting valve 72 from the liquid receiver 73. By increasing the amount of refrigerant flowing through the main refrigerant circuit, the temperature efficiency ε is brought closer to the target value.

However, if the amount of refrigerant in the entire refrigerant circuit including the main refrigerant circuit and the injection flow path 101 is insufficient in the first place, the amount of refrigerant sufficient for the main refrigerant circuit even if the opening degree of the flow rate adjusting valve 72 is increased. Is not circulated, so it is assumed that the temperature efficiency ε does not approach the target value and falls below the target value.

In view of this point, when the temperature efficiency ε of the heat exchanger 30 falls below the lower limit value lower than the target value, the control device 100 determines that the refrigerant in the entire refrigerant circuit is insufficient, and determines the determination result. The notification device 150 is controlled so as to notify the user.

(Adjusting the amount of refrigerant in the supercritical state and detecting refrigerant shortage)
Refrigerant amount adjustment and refrigerant shortage determination using temperature efficiency ε, which are performed in a normal state, have high determination accuracy and good followability. However, under the operating conditions in the supercritical state, the saturation temperature cannot be defined and supercooling cannot be confirmed. Therefore, the amount of refrigerant is adjusted and the refrigerant is insufficient by the same method as in the normal state (that is, the method using the temperature efficiency ε). It is difficult to make a judgment.

In view of this point, the control device 100 adjusts the amount of refrigerant and determines the refrigerant shortage by a method different from the normal state, that is, a method that does not use the temperature efficiency ε, under the operating conditions in the supercritical state. Specifically, under operating conditions in a supercritical state, the control device 100 has a temperature difference between the outside air temperature TA detected by the temperature sensor 123 and the refrigerant temperature T1 at the outlet of the condenser 20 detected by the temperature sensor 121. The opening degree of the flow rate adjusting valve 72 is controlled by using ΔT1. By using the temperature difference ΔT1, it is possible to adjust the amount of refrigerant with respect to the limit temperature of heat exchange by the condenser 20 (air heat exchanger) by utilizing the fact that there is a density change due to a change in the refrigerant temperature. For example, when the temperature difference ΔT1 is large, it is considered that excess refrigerant is stored in the receiver 73 and the amount of refrigerant in the main refrigerant circuit is insufficient, so that the control device 100 has a large temperature difference ΔT1. The opening degree of the flow rate adjusting valve 72 is increased accordingly. As a result, the amount of liquid refrigerant flowing from the liquid receiver 73 to the main refrigerant circuit is increased.

Further, under the operating conditions in the supercritical state, the control device 100 determines whether or not there is a shortage of refrigerant based on the “opening of the flow rate adjusting valve 72” which is feedback-controlled according to the temperature difference ΔT1 as described above. ..

For example, when the temperature difference ΔT1 is large, the opening degree of the flow rate adjusting valve 72 is increased according to the magnitude of the temperature difference ΔT1 by the feedback control of the refrigerant amount adjustment described above. As a result, the amount of liquid refrigerant flowing from the receiver 73 to the main refrigerant circuit is increased.

However, if the amount of refrigerant in the entire refrigerant circuit including the main refrigerant circuit and the injection flow path 101 is insufficient in the first place, even if the opening degree of the flow rate adjusting valve 72 is increased to the upper limit opening, the main refrigerant circuit is used. It is assumed that a sufficient amount of refrigerant does not circulate and the temperature difference ΔT1 does not change (do not decrease).

In view of this point, when the temperature difference ΔT1 does not change even if the opening degree of the flow rate adjusting valve 72 has reached the upper limit opening for a certain period of time, the control device 100 includes the main refrigerant circuit and the injection circuit. It is determined that the amount of refrigerant in the entire refrigerant circuit is insufficient, and the notification device 150 is controlled so as to notify the user of the determination result.

The method of determining the refrigerant shortage based on the "opening of the flow rate adjusting valve 72", which is feedback-controlled according to the temperature difference ΔT1, may deteriorate the followability as compared with the method using the temperature efficiency ε. By switching the determination method to, it becomes possible to determine the presence or absence of refrigerant shortage in the entire operating range including the normal state and the supercritical state.

(Adjustment of refrigerant filling amount)
Hereinafter, the adjustment of the amount of the refrigerant filled when the refrigerant is filled in the refrigerant circuit will be described. At the time of initial filling in which the refrigerant is filled in the refrigerant circuit that is not filled with the refrigerant for the first time, conventionally, for example, a sight glass is provided in the pipe 83 and adjustment is made by checking whether flash gas is present in the refrigerant of the pipe 83. rice field.

However, in the refrigerant circuit according to the present embodiment, in order to reduce the pressure in the load device 3, in addition to the expansion by the first expansion valve 50 in the load device 3, the expansion by the second expansion valve 40 in the outdoor unit 2 Is performed. When expansion is performed by the second expansion valve 40, the relationship between the amount of refrigerant and supercooling in the pipe 83 is not established. Therefore, the filling amount is adjusted by utilizing the above-mentioned determination result of insufficient refrigerant amount. Specifically, the filling of the refrigerant is continued while it is determined that the refrigerant is insufficient, and when it is no longer determined that the refrigerant is insufficient, it is determined that an appropriate amount of the refrigerant has been filled and the filling of the refrigerant is stopped.

The refrigerant may be filled manually by the user of the outdoor unit 2 (including the contractor who installs the outdoor unit 2), or may be automatically filled by the control device 100. Hereinafter, an example in which the control device 100 automatically performs initial encapsulation will be described.

At the time of initial filling, first, the control device 100 fills the refrigerant circuit with the refrigerant in the state where the compressor 10 is stopped until the discharge pressure PH of the compressor 10 detected by the pressure sensor 111 reaches the threshold value. After that, the control device 100 operates the compressor 10 to continue filling the refrigerant. At this time, since the discharge pressure PH of the compressor 10 is not supercritical, the refrigerant shortage detection using the temperature efficiency ε (refrigerant shortage detection in the normal state) is performed. The control device 100 continues to fill the refrigerant while it is determined that the refrigerant is insufficient by the refrigerant shortage detection (the refrigerant shortage detection in the normal state) using the temperature efficiency ε.

After that, when the rotation speed of the compressor 10 increases and the discharge pressure PH of the compressor 10 exceeds the critical pressure, the “opening of the flow rate adjusting valve 72” which is feedback-controlled according to the temperature difference ΔT1 is used. Refrigerant shortage detection (refrigerant shortage detection in a supercritical state) is performed. If the opening degree of the flow rate adjusting valve 72 does not reach the upper limit opening degree after the discharge pressure PH of the compressor 10 exceeds the critical pressure, it is not determined that the refrigerant shortage is detected. Therefore, the control device 100 determines that an appropriate amount of refrigerant has been filled and stops the filling of the refrigerant when it is not determined that the refrigerant shortage is detected after the discharge pressure PH of the compressor 10 becomes supercritical. As a result, the accuracy and followability of the refrigerant filling can be ensured even at the time of initial filling in which the amount of the refrigerant changes drastically.

(Overflow judgment)
A case where the refrigerant circuit is excessively filled with the refrigerant will be described. In this case, the discharge pressure PH of the compressor 10 detected by the pressure sensor 111 rises and becomes a supercritical state exceeding the critical pressure. At this time, the flow rate adjusting valve 72 is lowered to the lower limit opening degree by the feedback control of the refrigerant amount adjustment described above. If the discharge pressure PH of the compressor 10 does not change (does not decrease) even after a certain period of time elapses while the flow rate adjusting valve 72 has the lower limit opening, the control device 100 determines that the refrigerant circuit is in the overfilled state. , The notification device 150 is controlled so as to notify the user of the determination result.

After the overfilled state is determined, the control device 100 determines whether or not the magnitude of the rate of decrease in the discharge temperature TH of the compressor 10 detected by the temperature sensor 120 is larger than the reference value. Then, in the control device 100, when the magnitude of the decrease rate of the discharge temperature TH is larger than the reference value, that is, when the discharge temperature TH is rapidly decreased, the receiver 73 is filled with the liquid refrigerant. The notification device 150 is controlled so as to determine that it is in a state and notify the user of the determination result.

After determining that the overflow state is determined, the control device 100 determines whether or not the discharge superheat degree, which is the difference between the discharge temperature TH of the compressor 10 and the saturation temperature at the discharge pressure PH, is within the specification range of the compressor 10. If the discharge superheat degree is not within the specification range of the compressor 10, the compressor 10 is stopped.

(Flow of control for adjusting the amount of refrigerant and detecting refrigerant shortage)
FIG. 5 is a flowchart showing an example of a processing procedure when the control device 100 adjusts the amount of refrigerant and detects a shortage of refrigerant.

The control device 100 determines whether or not the discharge pressure PH of the compressor 10 exceeds the critical pressure (step S10). When the discharge pressure PH of the compressor 10 is in a supercritical state exceeding the critical pressure (YES in step S10), the control device 100 has the outside air temperature TA and the refrigerant temperature T1 at the outlet of the condenser 20 as described above. The opening degree of the flow rate adjusting valve 72 is controlled by using the temperature difference ΔT1 with and from (step S11). For example, when the temperature difference ΔT1 is large, the control device 100 increases the opening degree of the flow rate adjusting valve 72 according to the magnitude of the temperature difference ΔT1.

Next, the control device 100 determines whether or not the opening degree of the flow rate adjusting valve 72 is the upper limit opening degree (step S12). When the opening degree of the flow rate adjusting valve 72 is not the upper limit opening degree (NO in step S12), the control device 100 shifts the process to step S22.

On the other hand, when the opening degree of the flow rate adjusting valve 72 is the upper limit opening (YES in step S12), the control device 100 determines whether or not the state in which the opening degree of the flow rate adjusting valve 72 is the upper limit opening continues for a certain period of time. Is determined (step S14). When the state in which the opening degree of the flow rate adjusting valve 72 is the upper limit opening degree does not continue for a certain period of time (NO in step S14), the control device 100 skips the subsequent processing and shifts the processing to the return.

When the state in which the opening degree of the flow rate adjusting valve 72 is the upper limit opening continues for a certain period of time (YES in step S14), the control device 100 determines that the refrigerant in the entire refrigerant circuit is insufficient, and uses the determination result. The notification device 150 is controlled so as to notify the person (step S16).

On the other hand, when the discharge pressure PH of the compressor 10 is in a normal state where the discharge pressure PH does not exceed the critical pressure (NO in step S10), the control device 100 exchanges heat with the refrigerant temperature T1 at the outlet of the condenser 20 as described above. The temperature efficiency ε of the heat exchanger 30 is calculated from the difference in the outlet temperature T2 of the vessel 30, and the flow rate adjusting valve 72 is controlled according to the calculated temperature efficiency ε (step S20).

Next, the control device 100 determines whether or not the calculated temperature efficiency ε is less than the lower limit value (step S21). When the temperature efficiency ε is less than the lower limit value (YES in step S21), the control device 100 determines that the refrigerant in the entire refrigerant circuit is insufficient, and causes the notification device 150 to notify the user of the determination result. Control (step S40).

On the other hand, when the temperature efficiency ε is not less than the lower limit value (NO in step S21), the control device 100 shifts the process to step S22.

In step S22, the control device 100 determines whether or not the opening degree of the flow rate adjusting valve 72 is the lower limit opening degree. When the opening degree of the flow rate adjusting valve 72 is not the lower limit opening degree (NO in step S22), the control device 100 skips the subsequent processing and shifts the processing to the return.

When the opening degree of the flow rate adjusting valve 72 is the lower limit opening (YES in step S22), the control device 100 is a compressor even after the state in which the opening degree of the flow rate adjusting valve 72 is the lower limit opening continues for a certain period of time. It is determined whether or not the discharge pressure PH of 10 is larger than the threshold value (step S24). The "threshold value" used in step S24 is set to a value lower than, for example, the critical pressure. When the state in which the opening degree of the flow rate adjusting valve 72 is the lower limit opening degree does not continue for a certain period of time, or when the discharge pressure PH of the compressor 10 is less than the threshold value (NO in step S24), the control device 100 determines. The subsequent processing is skipped and the processing is moved to the return.

If the discharge pressure PH of the compressor 10 is larger than the threshold value even after the state in which the opening degree of the flow rate adjusting valve 72 is the lower limit opening degree continues for a certain period of time (YES in step S24), the refrigerant circuit of the control device 100 has a refrigerant circuit. The notification device 150 is controlled so as to determine that the overfilled state is present and notify the user of the determination result (step S26).

After the determination of the overfilled state, the control device 100 determines whether or not the discharge temperature TH of the compressor 10 is rapidly reduced, specifically, the magnitude of the rate of decrease of the discharge temperature TH of the compressor 10. It is determined whether or not it is larger than the reference value (step S28). Then, in the control device 100, when the magnitude of the decrease rate of the discharge temperature TH is larger than the reference value, that is, when the discharge temperature TH is rapidly decreased, the receiver 73 is filled with the liquid refrigerant. The notification device 150 is controlled so as to determine that the state is in the state and notify the user of the determination result (step S30).

After determining that the overflow state is determined, the control device 100 determines that the discharge superheat degree, which is the difference between the discharge temperature TH of the compressor 10 and the saturation temperature at the discharge pressure PH of the compressor 10, is within the specification range of the compressor 10. It is determined whether or not it fits (step S32). When the discharge superheat degree is within the specification range of the compressor 10 (NO in step S32), the control device 100 skips the subsequent processing and shifts the processing to the return. On the other hand, when the discharge superheat degree is not within the specification range of the compressor 10 (YES in step S32), the control device 100 stops the compressor 10 (step S34).

As described above, the control device 100 according to the present embodiment determines the presence or absence of refrigerant shortage by using the temperature efficiency ε of the heat exchanger 30 under the operating conditions under the normal state. On the other hand, under the operating conditions in the supercritical state, the control device 100 does not use the temperature efficiency ε of the heat exchanger 30, but responds to the temperature difference ΔT1 between the outside air temperature TA and the refrigerant temperature T1 at the outlet of the condenser 20. The presence or absence of a refrigerant shortage is determined by using the “opening of the flow rate adjusting valve 72” which is feedback-controlled. By switching the method for determining the refrigerant shortage in this way, it is possible to appropriately determine the presence or absence of the refrigerant shortage in the refrigerant circuit even under operating conditions in a supercritical state. As a result, in the refrigeration cycle apparatus 1 in which a refrigerant that can be in a supercritical state is used, it becomes possible to determine the presence or absence of a refrigerant shortage in the entire operating range including the normal state and the supercritical state.

Although the refrigerator provided with the refrigeration cycle device 1 has been described as an example in the above-described embodiment, the refrigeration cycle device 1 may be used as an air conditioner or the like.

The embodiments disclosed this time should be considered to be exemplary in all respects and not restrictive. The scope of the present disclosure is indicated by the scope of claims rather than the above description, and is intended to include all modifications within the meaning and scope of the claims.

1 Refrigeration cycle device, 2 Outdoor unit, 3 Load device, 10 Compressor, 20 Condenser, 22 Fan, 30 Heat exchanger, 40 2nd expansion valve, 50 1st expansion valve, 60 Evaporator, 71 3rd expansion valve , 72 Flow control valve, 73 Liquid receiver, 75 On-off valve, 80, 81-83, 85, 89, 91-94, 96 piping, 84, 88 extension piping, 95 degassing passage, 100 control device, 101 injection flow Road, 102 CPU, 104 memory, 110-113 pressure sensor, 120-125 temperature sensor, 150 notification device, G1 suction port, G2 discharge port, G3 intermediate pressure port, H1 first passage.

Claims (8)

1. An outdoor unit of a refrigeration cycle device configured to be connected to a load device including a first expansion valve and an evaporator.
   A compressor with a suction port, a discharge port and an intermediate pressure port,
   Condenser and
   A heat exchanger having a first passage and a second passage and exchanging heat between the refrigerant flowing through the first passage and the refrigerant flowing through the second passage.
   Equipped with a second expansion valve
   The flow path from the compressor to the condenser, the first passage of the heat exchanger, and the second expansion valve forms a circulation flow path through which the refrigerant circulates together with the load device.
   An injection flow path for flowing a refrigerant from the branch portion between the outlet of the condenser and the inlet of the first passage in the circulation flow path to the compressor is further provided.
   In the injection flow path,
   A first refrigerant flow path for flowing a refrigerant from the branch portion to the inlet of the second passage,
   A second refrigerant flow path for flowing a refrigerant from the outlet of the second passage to the suction port or the intermediate pressure port of the compressor.
   The receiver arranged in the first refrigerant flow path and
   A third expansion valve arranged in a portion between the branch portion and the inlet of the liquid receiver in the first refrigerant flow path.
   A flow rate adjusting valve arranged in a portion between the outlet of the liquid receiver and the inlet of the second passage in the first refrigerant flow path is provided.
   A control device that controls the compressor, the second expansion valve, the third expansion valve, and the flow rate adjusting valve.
   A notification device for notifying the user of information from the control device is further provided.
   When the discharge pressure of the compressor is in a supercritical state exceeding the critical pressure of the refrigerant, the control device includes the refrigerant contained in the circulation flow path and the injection flow path based on the opening degree of the flow rate adjusting valve. An outdoor unit that determines if there is a shortage.
2. When the control device is in the supercritical state, the larger the difference between the discharge temperature of the compressor and the outside air temperature, the larger the opening degree of the flow rate adjusting valve, whereby the circulation flow path from the liquid receiver to the circulation flow path. Increase the amount of refrigerant flowing into
   The control device is a refrigerant contained in the circulation flow path and the injection flow path when the state of the supercritical state and the opening degree of the flow rate adjusting valve is the upper limit opening degree continues for a certain period of time. The outdoor unit according to claim 1, wherein it is determined that the amount is insufficient.
3. When the control device is not in the supercritical state and the temperature efficiency of the heat exchanger is less than the lower limit value, it is determined that the refrigerant contained in the circulation flow path and the injection flow path is insufficient. The outdoor unit according to claim 2.
4. When the control device is not in the supercritical state, the larger the temperature efficiency of the heat exchanger, the smaller the opening degree of the flow rate adjusting valve, thereby reducing the amount of refrigerant flowing from the receiver to the circulation flow path. Let me
   When the control device is not in the supercritical state and the state in which the opening degree of the flow rate adjusting valve is the lower limit opening continues for a certain period of time, the refrigerant contained in the circulation flow path and the injection flow path is charged. The outdoor unit according to claim 2 or 3, which is determined to be excessive.
5. The outdoor unit according to claim 3 or 4, wherein the control device calculates the temperature efficiency of the heat exchanger from the difference between the inlet temperature and the outlet temperature of the heat exchanger.
6. When the magnitude of the rate of decrease in the discharge temperature of the compressor is larger than the reference value, the control device determines that the receiver is filled with the liquid refrigerant and stops the compressor. , The outdoor unit according to any one of claims 1 to 5.
7. Any one of claims 1 to 6, wherein the control device adjusts the opening degree of the second expansion valve so that the outlet pressure of the second expansion valve in the circulation flow path does not exceed the design pressure of the load device. The outdoor unit according to item 1.
8. A refrigeration cycle device including the outdoor unit according to any one of claims 1 to 7 and the load device.

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