WO2023120448A1

WO2023120448A1 - Heat source unit and refrigeration device

Info

Publication number: WO2023120448A1
Application number: PCT/JP2022/046568
Authority: WO
Inventors: 東近藤; 覚阪江; 千晴冨田; 一輝浮田
Original assignee: ダイキン工業株式会社
Priority date: 2021-12-21
Filing date: 2022-12-19
Publication date: 2023-06-29
Also published as: JP2023092358A; JP7348547B2

Abstract

A heat source unit (2) is connected to a utilization unit (5), thereby constituting a refrigerant circuit that performs a refrigeration cycle. The heat source unit (2) comprises a compressor (21), a first heat exchanger (24), a receiver (26), a first flow path (P1), and a first valve (V1). The compressor (21) compresses a refrigerant. The first heat exchanger (24) is used as a condenser for the refrigerant. The receiver (26) accumulates the refrigerant from the first heat exchanger (24) during normal operation when the first heat exchanger (24) is used as the condenser. The first flow path (P1) bypasses the first heat exchanger (24) and connects the discharge side of the compressor (21) and the receiver (26). The first valve (V1) opens and closes the first flow path (P1). The first valve (V1) opens during refrigerant amount detection operation for detecting the amount of refrigerant in the refrigerant circuit (10).

Description

Heat source unit and refrigerator

Regarding heat source units and refrigeration equipment.

In Patent Document 1 (Japanese Patent Application Laid-Open No. 2015-75259), normal operation, which is a refrigeration cycle operation according to the heat load required from the heat exchanger on the user side, and the appropriateness of the amount of refrigerant in the refrigerant circuit are determined. A refrigerating apparatus capable of switching between a refrigerant amount determination operation, which is a refrigeration cycle operation, is disclosed. In the refrigerating apparatus of Patent Literature 1, in the refrigerant amount determination operation, the refrigerant is caused to flow through the receiver bypass pipe to bypass the receiver.

In the refrigeration system of Patent Document 1, the receiver is at a high temperature during normal operation, and the receiver is at a low temperature during the refrigerant amount determination operation. Therefore, if the refrigerant amount judgment operation is frequently performed, phenomena such as dew condensation on the outer shell of the receiver and thermal stress acting on the pipe joints occur due to the repetition of the high temperature state and the low temperature state of the receiver. Therefore, the refrigerating device of Patent Document 1 needs to be painted or brazed in order to withstand this phenomenon.

A heat source unit according to the first aspect is a heat source unit that configures a refrigerant circuit that performs a refrigeration cycle by being connected to a usage unit. The heat source unit includes a compressor, a first heat exchanger, a receiver, a first flow path, and a first valve. The compressor compresses refrigerant. The first heat exchanger is used as a refrigerant condenser. The receiver collects refrigerant discharged from the first heat exchanger during normal operation using the first heat exchanger as a condenser. The first flow path bypasses the first heat exchanger and connects the discharge side of the compressor and the receiver. The first valve opens and closes the first flow path. The first valve opens during a refrigerant amount detection operation for detecting the amount of refrigerant in the refrigerant circuit.

According to the heat source unit of the first aspect, since the first valve is opened during the refrigerant amount detection operation, the refrigerant discharged from the compressor is sent to the receiver via the first flow path bypassing the first heat exchanger. be able to. As a result, the refrigerant amount detection operation can be performed in a state in which the liquid refrigerant in the receiver is pushed out to the refrigerant circuit and the receiver is filled with gas refrigerant. Therefore, even if the refrigerant amount detection operation is performed, the receiver can maintain a high temperature state. Therefore, even if the frequency of the refrigerant quantity detection operation is increased, phenomena such as dew condensation on the outer shell of the receiver and thermal stress acting on the pipe joints can be reduced.

The heat source unit according to the second aspect is the heat source unit according to the first aspect and further includes a control section. The control unit closes the first valve during normal operation and opens the first valve during refrigerant amount detection operation.

In the heat source unit according to the second aspect, during normal operation using the first heat exchanger as a condenser, the first valve is closed and the first flow path is not used. Therefore, normal operation and refrigerant amount detection operation can be appropriately performed.

The heat source unit according to the third aspect is the heat source unit according to the first aspect or the second aspect, and further includes a second flow path. A second flow path is connected to the first heat exchanger and bypasses the receiver. During the refrigerant amount sensing operation, the refrigerant flows from the first heat exchanger to the second flow path.

In the heat source unit according to the third aspect, it is possible to reduce the amount of refrigerant sent to the receiver by causing the refrigerant to flow through the second channel during the refrigerant amount detection operation. Therefore, it is possible to suppress accumulation of the liquid refrigerant in the receiver, so that it is possible to improve the accuracy of detecting the refrigerant amount in the refrigerant amount detection operation.

The heat source unit according to the fourth aspect is the heat source unit according to the third aspect and further includes a second valve. The second valve opens and closes the second flow path.

In the heat source unit according to the fourth aspect, during the refrigerant amount detection operation, the second valve is opened to allow the refrigerant to flow through the second flow path, and during normal operation, the second valve is closed to allow the second flow path to flow. It is possible to suppress the coolant from flowing through the flow path. Therefore, normal operation and refrigerant amount detection operation can be performed more appropriately.

The heat source unit according to the fifth aspect is the heat source unit according to the first to fourth aspects, and further includes a third valve. A third valve is positioned downstream of the receiver during normal operation. The degree of opening of the third valve is reduced during the refrigerant amount detection operation.

In the heat source unit according to the fifth aspect, it is possible to prevent the density of the liquid refrigerant from becoming too low by reducing the degree of opening of the third valve arranged downstream of the receiver during the refrigerant amount detection operation.

The heat source unit according to the sixth aspect is the heat source unit according to the fifth aspect, further comprising a second flow path. A second flow path is connected to the first heat exchanger and bypasses the receiver. The second flow path further bypasses the third valve.

In the heat source unit according to the sixth aspect, the refrigerant can flow through the second channel that bypasses the receiver and the third valve during the refrigerant amount detection operation. Therefore, the refrigerant amount detection operation can be performed while preventing the density of the liquid refrigerant from becoming too low.

The heat source unit according to the seventh aspect is the heat source unit according to the fifth aspect or sixth aspect, further comprising a second flow path and a second valve. A second flow path is connected to the first heat exchanger and bypasses the receiver. The second valve opens and closes the second flow path. During the refrigerant amount detection operation, after the first valve is opened, the second valve is opened and the degree of opening of the third valve is reduced.

In the heat source unit according to the seventh aspect, the first valve is opened to push out the liquid refrigerant in the receiver, and then the second valve is opened to suppress accumulation of the liquid refrigerant in the receiver. By reducing the degree of opening of the valve, it is possible to prevent the density of the liquid refrigerant from becoming too low. Therefore, the amount of refrigerant can be detected while maintaining the density of the liquid refrigerant.

A heat source unit according to an eighth aspect is the heat source unit according to the first aspect to the seventh aspect, wherein the refrigerant amount detection operation is performed by using the condenser outlet temperature when the first heat exchanger is used as a condenser, the high pressure of the refrigerant circuit, , the low pressure of the refrigerant circuit, the outlet temperature of the receiver, the outside air temperature, the evaporation temperature, and the number of revolutions of the compressor are used to detect the amount of refrigerant.

In the heat source unit according to the eighth aspect, the amount of refrigerant is detected using at least one of the condenser outlet temperature, high pressure, low pressure, receiver outlet temperature, outside air temperature, evaporation temperature, and compressor rotation speed, Refrigerant amount detection operation can be easily realized.

A refrigeration apparatus according to the ninth aspect includes the heat source unit and the utilization unit of the first to eighth aspects. The utilization unit is connected to the heat source unit and includes a second heat exchanger.

The refrigeration system of the ninth aspect is equipped with the heat source unit described above. Therefore, even if the frequency of the refrigerant amount detection operation is increased, phenomena such as dew condensation on the outer shell of the receiver and thermal stress acting on the pipe joints can be reduced. realizable.

1 is a schematic configuration diagram of a refrigeration system according to an embodiment; FIG. It is a control block diagram of refrigeration according to the embodiment. FIG. 4 is a diagram showing the operation (refrigerant flow) in cooling operation of normal operation; FIG. 4 is a diagram showing the operation (refrigerant flow) in the refrigerant amount detection operation; FIG. 4 is a diagram showing the operation (refrigerant flow) in the refrigerant amount detection operation; 4 is a flow chart of a refrigerant amount detection operation;

A refrigerating device according to an embodiment of the present disclosure will be described with reference to the drawings.

(1) Refrigeration Equipment (1-1) Overall Configuration As shown in FIG. 1, a refrigeration equipment 1 cools the inside of a low-temperature warehouse, a shipping container, a showcase of a store, etc. by means of a vapor compression refrigeration cycle. It is a device.

The refrigerator 1 mainly has a heat source unit 2, a utilization unit 5, connecting

pipes

6 and 7, and a control section 8.

Communication pipes

6 and 7 connect the heat source unit 2 and the utilization unit 5 . The controller 8 controls components of the heat source unit 2 and the utilization unit 5 . A vapor compression refrigerant circuit 10 of the refrigeration system 1 is configured by connecting the heat source unit 2 , the utilization unit 5 , and the

connection pipes

6 and 7 .

The refrigeration system 1 is configured to be able to perform normal operation and refrigerant amount detection operation. The refrigerant amount detection operation is a refrigeration cycle operation for detecting the amount of refrigerant in the refrigerant circuit 10 . Normal operation is operation other than refrigerant amount determination operation. Also, the normal operation is a refrigeration cycle operation corresponding to the heat load requested by the utilization unit 5 . Here, the normal operation includes a cooling operation for cooling the inside of the refrigerator and a heating operation for heating the inside of the refrigerator.

(1-2) Detailed Configuration of Equipment (1-2-1) Heat Source Unit The heat source unit 2 is installed outdoors. As described above, the heat source unit 2 is connected to the utilization unit 5 via the connecting

pipes

6 and 7, and constitutes a part of the refrigerant circuit 10 that performs the refrigeration cycle.

Next, the configuration of the heat source unit 2 will be described. The heat source unit 2 mainly includes a compressor 21, a four-way switching valve 22, an accumulator 23, a first heat exchanger 24, a first fan 25, a receiver 26, a branch pipe 27, and a supercooling expansion valve. 28, a subcooling heat exchanger 29, a first valve V1, a second valve V2, a third valve V3, a first flow path P1, and a second flow path P2.

The compressor 21 is a device that compresses low-pressure refrigerant to high pressure. As the compressor 21, for example, a positive displacement compressor driven by a motor whose rotational speed is controlled by an inverter can be used.

The compressor 21 has a suction pipe 21a connected to the suction side and a discharge pipe 21b connected to the discharge side. The suction pipe 21 a is a refrigerant pipe that connects the suction side of the compressor 21 and the four-way switching valve 22 . The discharge pipe 21 b is a refrigerant pipe that connects the discharge side of the compressor 21 and the four-way switching valve 22 .

An accumulator 23 is connected to the intake pipe 21a. The accumulator 23 separates the inflowing refrigerant into liquid refrigerant and gas refrigerant, and allows only the gas refrigerant to flow to the suction side of the compressor 21 .

The four-way switching valve 22 is a valve for switching the refrigerant flow path. During cooling operation, the four-way switching valve 22 connects the discharge pipe 21b of the compressor 21 and the gas-side gas refrigerant pipe 24a of the first heat exchanger 24 (the solid line of the four-way switching valve 22 in FIG. reference). Thereby, the first heat exchanger 24 functions as a condenser for the refrigerant compressed by the compressor 21, and the second heat exchanger 52 functions as an evaporator for the refrigerant condensed in the first heat exchanger 24. do. During heating operation, the four-way switching valve 22 connects the discharge pipe 21b of the compressor 21 and the communication pipe 7 on the gas side, side gas refrigerant pipe 24a (see the dotted line of the four-way switching valve 22 in FIG. 1). Thereby, the second heat exchanger 52 functions as a condenser for the refrigerant compressed by the compressor 21, and the first heat exchanger 24 functions as an evaporator for the refrigerant condensed in the second heat exchanger 52. do.

The first heat exchanger 24 is a device for exchanging heat between air and refrigerant. The first heat exchanger 24 functions as a refrigerant condenser during cooling operation, and functions as a refrigerant evaporator during heating operation. As the first heat exchanger 24, for example, a cross-fin fin-and-tube heat exchanger can be used. However, the first heat exchanger 24 is not limited to this, and may be another type of heat exchanger.

A gas refrigerant pipe 24a is connected to the gas side of the first heat exchanger 24, and a liquid refrigerant pipe 24b is connected to the liquid side. The gas refrigerant pipe 24 a is a refrigerant pipe that connects the four-way switching valve 22 and the gas side end of the first heat exchanger 24 . The liquid refrigerant pipe 24b is a refrigerant pipe that connects the liquid side end of the first heat exchanger 24 and the liquid side communication pipe 6 . The liquid refrigerant pipe 24b is a flow path through which the refrigerant passes during the cooling operation.

The first fan 25 sucks outdoor air into the heat source unit 2, exchanges heat with the refrigerant in the first heat exchanger 24, and then discharges the air to the outside. As the first fan 25, for example, a centrifugal fan, a multi-blade fan, or the like driven by a motor such as a DC fan motor can be used.

The receiver 26 is a refrigerant container that stores surplus refrigerant in the refrigerant circuit 10 . The receiver 26 stores liquid refrigerant and adjusts the amount of refrigerant circulating in the refrigerant circuit 10 when the amount of refrigerant in the evaporator or the condenser changes due to changes in operating conditions. A receiver 26 is arranged between the first heat exchanger 24 and the subcooling heat exchanger 29 .

The branch pipe 27, the supercooling expansion valve 28, and the supercooling heat exchanger 29 constitute a supercooling circuit.

The branch pipe 27 connects the liquid refrigerant pipe 24b between the supercooling heat exchanger 29 and the third valve V3 and the suction side of the compressor 21. The branch pipe 27 branches a portion of the refrigerant that has exited the supercooling heat exchanger 29 during the cooling operation and sends the branch to the compressor 21 .

The supercooling expansion valve 28 is arranged on the branch pipe 27 . Specifically, the supercooling expansion valve 28 is arranged between the third valve V3 and the supercooling heat exchanger 29 on the branch pipe 27 . The subcooling expansion valve 28 reduces the pressure of the refrigerant exiting the subcooling heat exchanger 29 so that the subcooling heat exchanger 29 serves as a cooling source for the refrigerant entering from the inlet. Here, the supercooling expansion valve 28 is an electric expansion valve whose opening degree can be adjusted.

The supercooling heat exchanger 29 exchanges heat between the refrigerant flowing through the branch pipe 27 on the downstream side of the supercooling expansion valve 28 and the refrigerant flowing through the liquid refrigerant pipe 24b on the downstream side of the first heat exchanger 24. Equipment. In the supercooling heat exchanger 29 , the refrigerant that has entered the branch pipe 27 and has been decompressed by the supercooling expansion valve 28 cools the refrigerant that has exited the first heat exchanger 24 . Thus, the subcooling heat exchanger 29 cools the refrigerant discharged from the first heat exchanger 24 during cooling operation using the first heat exchanger 24 as a condenser. As the supercooling heat exchanger 29, for example, a plate-type or double-tube heat exchanger can be used.

The first flow path P1 bypasses the first heat exchanger 24 and connects the discharge side of the compressor 21 and the receiver 26 . The first flow path P1 is a pipe that bypasses the first heat exchanger 24 and sends the refrigerant discharged from the compressor 21 to the receiver 26 during the refrigerant amount detection operation. In addition, in FIG. 1, the 1st flow path P1 contains the discharge pipe 21b. Refrigerant flows through the first flow path P1 during refrigerant amount detection operation, and does not flow through the first flow path P1 during normal operation. In this embodiment, the refrigerant flows through the first flow path P1 during the refrigerant amount detection operation, and does not flow through the first flow path P1 during the cooling operation and the heating operation.

A first valve V1 for opening and closing the first flow path P1 is arranged in the first flow path P1. The first valve V1 is, for example, an electric valve, an electromagnetic valve, or the like. Here, the first valve V1 is an electrically operated valve whose opening cannot be adjusted. The first valve V1 is open during the refrigerant amount detection operation, and is closed during the normal operation. In this embodiment, the first valve V1 is opened during the refrigerant amount detection operation, and closed during the cooling operation and the heating operation.

The second flow path P2 is connected to the first heat exchanger 24 and bypasses the receiver 26. The second flow path P2 is a pipe for sending the refrigerant that has passed through the first heat exchanger 24 to the communication pipe 6 without passing through the receiver 26 during the refrigerant amount detection operation. The second flow path P2 is provided downstream of the first heat exchanger 24 during the refrigerant amount detection operation. In the present embodiment, the second flow path P2 connects the first heat exchanger 24 and a pipe on the downstream side of the supercooling heat exchanger 29 in the refrigerant flow during the refrigerant amount detection operation to Exchanger 29 is also bypassed. The second flow path P2 further bypasses the third valve V3.

A second valve V2 is arranged in the second flow path P2. The second valve V2 is, for example, an electric valve, an electromagnetic valve, or the like. Here, the second valve V2 is an electrically operated valve whose opening cannot be adjusted. The second valve V2 opens and closes the second flow path P2. The second valve V2 is opened during refrigerant amount detection operation, and closed during normal operation.

The third valve V3 is arranged downstream of the receiver 26 during normal operation (cooling operation in this embodiment). Here, the third valve V3 is arranged downstream of the subcooling heat exchanger 29 during normal operation (cooling operation in this embodiment). The degree of opening of the third valve V3 can be adjusted. Here, the third valve V3 is an electric expansion valve.

The degree of opening of the third valve V3 decreases during the refrigerant amount detection operation. In this embodiment, the third valve V3 is at the minimum opening during the refrigerant amount detection operation. During normal operation, the third valve V3 adjusts the flow rate of the refrigerant flowing through the first heat exchanger 24, and the like. The degree of opening of the third valve V3 during refrigerant amount detection operation is smaller than the degree of opening of the third valve V3 during normal operation. Here, the degree of opening of the third valve V3 is reduced when the normal operation is switched to the refrigerant amount detection operation.

During the refrigerant amount detection operation, after the first valve V1 opens, the second valve V2 opens and the opening degree of the third valve V3 decreases.

Also, the heat source unit 2 is provided with a plurality of check valves V4 to V9. Specifically, the first check valve V4 is arranged downstream of the first heat exchanger 24 in the refrigerant flow and upstream of the receiver 26 in the refrigerant flow. Also, the first check valve V4 is provided in the liquid refrigerant pipe 24b. The first check valve V4 allows the flow of refrigerant from the first heat exchanger 24 side and blocks the flow of refrigerant from the receiver 26 side.

The second check valve V5 is arranged between the receiver 26 and the first heat exchanger 24. The second check valve V5 allows the flow of refrigerant from the receiver 26 side and blocks the flow of refrigerant from the first heat exchanger 24 side.

The third check valve V6 is provided in the refrigerant pipe that bypasses the subcooling heat exchanger 29 during heating operation. The third check valve V6 allows the flow of refrigerant from the first stop valve 31 side and blocks the flow of refrigerant from the first heat exchanger 24 side.

The fourth check valve V7 is arranged between the third valve V3 and the first closing valve 31. The fourth check valve V7 permits the flow of refrigerant from the third valve V3 side and blocks the flow of refrigerant from the first stop valve 31 side.

The fifth check valve V8 is arranged between the four-way switching valve 22 and the accumulator 23. The fifth check valve V8 allows the flow of refrigerant from the four-way switching valve 22 side and blocks the flow of refrigerant from the accumulator 23 side.

The sixth check valve V9 is arranged between the compressor 21 and the four-way switching valve 22. The sixth check valve V9 permits the flow of refrigerant from the compressor 21 side and blocks the flow of refrigerant from the four-way switching valve 22 side.

Also, the heat source unit 2 is provided with closing

valves

31 and 32 . The first shut-off valve 31 is provided at the connecting portion between the heat source unit 2 and the connecting pipe 6 . The second shutoff valve 32 is provided at the connecting portion between the heat source unit 2 and the connecting pipe 7 . The first shut-off valve 31 and the second shut-off valve 32 are valves that are manually opened and closed. Here, liquid refrigerant flows through the first closing valve 31 and gas refrigerant flows through the second closing valve 32 .

Also, the heat source unit 2 is provided with various sensors. Specifically, as shown in FIGS. 1 and 2, the heat source unit 2 includes a suction pressure sensor 41, a discharge pressure sensor 42, a suction temperature sensor 43, a discharge temperature sensor 44, an outdoor temperature sensor 45, and a first heat exchange sensor. A vessel outlet temperature sensor 46, a subcooling heat exchanger outlet temperature sensor 47 and a receiver outlet temperature sensor 48 are provided. A suction pressure sensor 41 detects the suction pressure of the compressor 21 . A discharge pressure sensor 42 detects the discharge pressure of the compressor 21 . A suction temperature sensor 43 detects the suction temperature of the compressor 21 . A discharge temperature sensor 44 detects the discharge temperature of the compressor 21 . The outdoor temperature sensor 45 detects the temperature of outdoor air flowing into the heat source unit 2 . A first heat exchanger outlet temperature sensor 46 detects the outlet temperature of the condenser when the first heat exchanger is used as the condenser. A supercooling heat exchanger outlet temperature sensor 47 detects the outlet temperature of the supercooling heat exchanger 29 when the first heat exchanger 24 is used as a condenser. Receiver outlet temperature sensor 48 detects the outlet temperature of receiver 26 .

(1-2-2) Usage Unit The usage unit 5 is an internal unit that cools the interior of the refrigerator. The utilization unit 5 is connected to the heat source unit 2 via connecting

pipes

6 and 7 and forms part of the refrigerant circuit 10 .

The usage unit 5 mainly has a usage side expansion valve 51 , a second heat exchanger 52 and a second fan 53 .

The user-side expansion valve 51 is an electric expansion valve or the like connected to the liquid side of the second heat exchanger 52 and adjusts the flow rate of the refrigerant flowing through the second heat exchanger 52 . Also, the user-side expansion valve 51 can block passage of the refrigerant.

The second heat exchanger 52 is a device for exchanging heat between the air inside the refrigerator and the refrigerant. The second heat exchanger 52 functions as a refrigerant evaporator during the cooling operation, and cools the air inside the refrigerator. Further, the second heat exchanger 52 functions as a refrigerant condenser during the heating operation, and heats the air in the refrigerator. As the second heat exchanger 52, for example, a cross-fin type fin-and-tube heat exchanger composed of heat transfer tubes and a large number of fins can be used. However, the second heat exchanger 52 is not limited to this, and may be another type of heat exchanger.

The second fan 53 sucks air into the usage unit 5 and supplies the air heat-exchanged with the refrigerant in the second heat exchanger 52 into the refrigerator. As the second fan 53, for example, a centrifugal fan or a multi-blade fan driven by a motor such as a DC fan motor can be used.

Also, the usage unit 5 is provided with various sensors. Specifically, the utilization unit 5 is provided with an in-chamber temperature sensor 54, a second heat exchanger inlet temperature sensor 55, and a second heat exchanger outlet temperature sensor 56 shown in FIG. The in-chamber temperature sensor 54 detects the temperature of the air flowing into the utilization unit 5 (in-chamber temperature). A second heat exchanger inlet temperature sensor 55 detects the temperature of the refrigerant at the inlet of the second heat exchanger 52 (on the liquid-liquid side during cooling operation). A second heat exchanger outlet temperature sensor 56 detects the temperature of the refrigerant at the outlet of the second heat exchanger 52 (on the gas side during cooling operation).

(1-2-3) Connecting

Pipes Connecting pipes

6 and 7 are refrigerant pipes that are installed on site when the refrigeration system 1 is installed at the installation site. The connecting

pipes

6 and 7 have different lengths and pipe diameters depending on conditions such as the combination of the heat source unit 2 and the utilization unit 5 and the installation location. For this reason, for example, when installing a new air conditioner, it is necessary to fill an appropriate amount of refrigerant according to conditions such as the length and diameter of the connecting

pipes

6 and 7 . Here, liquid refrigerant flows through the connecting pipe 6 and gas refrigerant flows through the connecting pipe 7 .

(1-3) Detailed Configuration of Control As shown in FIG. It has a control unit 8 connected via a communication line. The first controller 81 is provided in the heat source unit 2 . The second control section 82 is provided in the usage unit 5 . Here, the first controller 81, the second controller 82, and the remote controller 60 are wiredly connected via a transmission line or a communication line, but may be wirelessly connected.

The first control unit 81, the second control unit 82, and the control device of the remote controller 60 of the refrigeration apparatus 1 perform various calculations and processes, and are realized by a calculation processing device such as a CPU, for example.

(1-3-1) First Control Section The first control section 81 controls the operation of each section that configures the heat source unit 2 . The first control section 81 mainly has a first CPU 81a, a first transmission section 81b, and a first storage section 81c. The first control unit 81 includes a suction pressure sensor 41, a suction temperature sensor 43, a discharge pressure sensor 42, a discharge temperature sensor 44, an outdoor temperature sensor 45, a first heat exchanger outlet temperature sensor 46, and a supercooling heat exchanger outlet temperature sensor. 47 and receiver outlet temperature sensor 48.

The first CPU 81a is connected to the first transmission section 81b and the first storage section 81c. The first transmission section 81 b transmits control data and the like to and from the second control section 82 . The first storage unit 81c stores control data and the like. Then, the first CPU 81a transmits, reads and writes control data and the like via the first transmission section 81b and the first storage section 81c, and the compressor 21 and the four-way switching as components provided in the heat source unit 2. It controls the operation of the valve 22, the first fan 25, the first valve V1, the second valve V2, the third valve V3, the supercooling expansion valve 28, and the like.

(1-3-2) Second Control Section The second control section 82 controls the operation of each section that configures the usage unit 5 . The second control section 82 mainly has a second CPU 82a, a second transmission section 82b, a second storage section 82c, and a second communication section 82d. The second control unit 82 is configured to receive detection signals from the inside temperature sensor 54 , the second heat exchanger inlet temperature sensor 55 and the second heat exchanger outlet temperature sensor 56 .

The second CPU 82a is connected to the second transmission section 82b, the second storage section 82c and the second communication section 82d. The second transmission section 82 b transmits control data and the like to and from the first control section 81 . The second storage unit 82c stores control data and the like. The second communication unit 82d transmits and receives control data and the like to and from the remote controller 60. FIG. The second CPU 82a transmits, reads, writes, and transmits/receives control data and the like via the second transmission section 82b, the second storage section 82c, and the second communication section 82d, and performs It controls the operation of the second fan 53, the user-side expansion valve 51, and the like.

(1-3-3) Remote Controller The remote controller 60 is used by the user to input various settings. The remote control 60 mainly includes a remote control CPU 61 , a remote control storage section 62 , a remote control communication section 63 , a remote control operation section 64 and a remote control display section 65 .

The remote controller CPU 61 is connected to the remote controller storage unit 62 , the remote controller communication unit 63 , the remote controller operation unit 64 and the remote controller display unit 65 . The remote controller storage unit 62 stores control data and the like. The remote control communication unit 63 transmits and receives control data and the like to and from the second communication unit 82d. A remote control operation unit 64 receives an input such as a control command from a user. The remote control display unit 65 displays operation and the like. The remote control CPU 61 receives input of operation commands, control commands, etc. via the remote control operation unit 64 , reads and writes control data, etc. in the remote control storage unit 62 , and displays the operation state and control state on the remote control display unit 65 . While performing such operations, a control command or the like is issued to the second control unit 82 via the remote control communication unit 63 .

As described above, the refrigeration system 1 includes the control unit 8 that controls the operation of the components. The controller 8 controls the intake pressure sensor 41, the intake temperature sensor 43, the discharge pressure sensor 42, the discharge temperature sensor 44, the outdoor temperature sensor 45, the first heat exchanger outlet temperature sensor 46, and the supercooling heat exchanger outlet temperature sensor. 47, a compressor 21, a four-way The switching valve 22, the first fan 25, the supercooling expansion valve 28, the first valve V1, the second valve V2, the third valve V3, the second fan 53, the user-side expansion valve 51, etc. are controlled, and the cooling operation and heating are performed. It is configured to be able to perform operation, refrigerant amount detection operation, and various controls.

(1-3-4) Control of Normal Operation and Refrigerant Amount Detection Operation by First Control Unit The first control unit 81 performs control so as to switch between normal operation and refrigerant amount detection operation. The first control unit 81 controls

various devices

21, 22, 25 and various valves 28, V1 to V3 according to the heat load from the utilization unit 5 during normal operation.

The first control unit 81 closes the first valve V1 during normal operation so that the refrigerant does not flow through the first flow path P1.

Also, the first control unit 81 closes the second valve V2 during normal operation so that the refrigerant does not flow through the second flow path P2. Thereby, the first control unit 81 causes the refrigerant to flow from the first heat exchanger 24 to the receiver 26 through the liquid refrigerant pipe 24b during the cooling operation.

In addition, the first control unit 81 controls the degree of opening of the third valve V3 according to the heat load requested by the usage unit 5. Here, the first controller 81 fully opens the third valve V3 during the cooling operation.

The first control unit 81 opens the first valve V1 during the refrigerant amount detection operation for detecting the amount of refrigerant in the refrigerant circuit 10 . Here, the first control unit 81 opens the first valve V1 when switching to the refrigerant amount detection operation. Thereby, the first controller 81 causes the coolant to flow through the first flow path P1.

Also, the first control unit 81 opens the second valve V2 during the refrigerant amount detection operation. Thereby, the first controller 81 causes the refrigerant to flow from the first heat exchanger 24 to the second flow path P2. Here, the first control unit 81 causes the refrigerant to flow from the first heat exchanger 24 to the second flow path P2 that bypasses the receiver 26 and the third valve V3 during the refrigerant amount detection operation.

Also, the first control unit 81 reduces the degree of opening of the third valve V3 during the refrigerant amount detection operation. Here, the first control unit 81 sets the opening degree of the third valve V3 to the minimum opening degree when switching to the refrigerant amount detection operation.

Further, during the refrigerant amount detection operation, the first control unit 81 opens the second valve V2 after opening the first valve V1, and reduces the opening degree of the third valve V3.

Further, during the refrigerant amount detection operation, the first control unit 81 controls the condenser outlet temperature when the first heat exchanger 24 is used as a condenser, the high pressure of the refrigerant circuit 10, the low pressure of the refrigerant circuit 10, the outlet temperature of the receiver 26, and the , the ambient temperature, the evaporation temperature, and the rotation speed of the compressor 21 are used to detect the amount of refrigerant. The condenser outlet temperature is detected by the first heat exchanger outlet temperature sensor 46 . A high pressure in the refrigerant circuit 10 is detected by a discharge pressure sensor 42 . A low pressure in the refrigerant circuit 10 is detected by a suction pressure sensor 41 . The outlet temperature of receiver 26 is detected by receiver outlet temperature sensor 48 . The outdoor air temperature is detected by an outdoor temperature sensor 45 . The evaporation temperature is obtained by converting the suction pressure detected by the suction pressure sensor 41 into the saturation temperature of the refrigerant. The rotation speed of the compressor 21 is grasped from the compressor 21 .

In this embodiment, the degree of subcooling, which is the temperature difference between the condensation temperature of the refrigerant in the condenser and the outlet temperature of the condenser (specifically, the pressure of the refrigerant detected by the discharge pressure sensor 42 is converted into the saturation temperature. , the temperature difference obtained by subtracting the temperature of the refrigerant detected by the first heat exchanger outlet temperature sensor 46 from the saturation temperature) is used to perform the refrigerant amount detection operation.

(2) Operation of Refrigerating Device Next, the operation of the refrigerating device 1 of the present embodiment will be described with reference to FIGS. 1 to 5. FIG. In the refrigeration system 1, a cooling operation and a heating operation as normal operations and a refrigerant amount detection operation are performed. The cooling operation and the refrigerant amount detection operation will be described below. The operation of the refrigeration apparatus 1 described below is performed by a control section 8 having a first control section 81 and a second control section 82 that control the equipment configuration of the refrigeration apparatus 1 .

(2-1) Cooling Operation The operation of the cooling operation will be described with reference to FIG. In the cooling operation, the operating frequency of the compressor 21 is controlled so that the low pressure value of the refrigeration cycle (detected value of the suction pressure sensor 41) becomes a constant value, and the degree of superheat of the refrigerant at the outlet of the second heat exchanger 52 is The opening degree of the utilization side expansion valve 51 is adjusted so as to achieve a predetermined target value.

The cooling operation is performed by the control unit 8 that receives a cooling operation command via the remote control operation unit 64, and controls the compressor 21, the four-way switching valve 22, the first fan 25, This is performed by controlling the operations of the first valve V1, the second valve V2, the third valve V3, the user-side expansion valve 51, the second fan 53, and the like.

As shown in FIG. 3, during the cooling operation, the first valve V1 is closed to prevent the coolant from flowing through the first flow path P1. Also, during the cooling operation, the second valve V2 is closed to prevent the refrigerant from flowing through the second flow path P2. Further, during the cooling operation, the third valve V3 is fully opened. Further, during cooling operation, the discharge side of the compressor 21 is connected to the gas side of the first heat exchanger 24 by the four-way switching valve 22, and the suction side of the compressor 21 is connected via the communication pipe 7 on the gas side. It is connected to the gas side of the second heat exchanger 52 (see the solid line of the four-way switching valve 22 in FIG. 3). Also, during the cooling operation, the first heat exchanger 24 is used as a condenser.

In the cooling operation, low-pressure gas refrigerant is sucked into the compressor 21 and compressed into high-pressure gas refrigerant. The high-pressure gas refrigerant is sent to the first heat exchanger 24 via the check valve V9 and the four-way switching valve 22. The high-pressure gas refrigerant exchanges heat with the outdoor air supplied by the first fan 25 in the first heat exchanger 24 and is condensed into a high-pressure liquid refrigerant. The high-pressure liquid refrigerant is sent to the receiver 26 via the check valve V4, temporarily stored in the receiver 26, and then sent to the subcooling heat exchanger 29. The high-pressure liquid refrigerant further cooled by the subcooling heat exchanger 29 flows out of the heat source unit 2 via the third valve V3, the check valve V7 and the closing valve 31.

　Refrigerant flowing out from the heat source unit 2 is sent to the utilization unit 5 via the communication pipe 6 on the liquid side. In the usage unit 5 , the high-pressure liquid refrigerant is sent to the second heat exchanger 52 after being decompressed by the usage-side expansion valve 51 . In the second heat exchanger 52 , this refrigerant exchanges heat with the air in the chamber supplied by the second fan 53 and evaporates to become a low-pressure gas refrigerant. This low-pressure gas refrigerant flows out of the utilization unit 5 .

The refrigerant flowing out of the utilization unit 5 is sent to the heat source unit 2 via the gas-side communication pipe 7, via the shut-off valve 32, the four-way switching valve 22, the check valve V8, and the accumulator 23, and again, It is sucked into the compressor 21 .

Here, the role of the supercooling circuit of this embodiment during the cooling operation will be described. A portion of the refrigerant exiting the subcooling heat exchanger 29 is branched and sent to the compressor 21 through the branch pipe 27 . In the subcooling heat exchanger 29 , the refrigerant flowing through the branch pipe 27 and decompressed by the subcooling expansion valve 28 cools the refrigerant flowing to the usage unit 5 .

(2-2) Refrigerant Amount Detection Operation The operation of the refrigerant amount detection operation will be described mainly with reference to FIGS. 2 and 4 to 6. FIG. Here, an example will be described in which after the cooling operation as the normal operation is performed for a predetermined time, the refrigerant amount detection operation is performed to detect whether or not the amount of refrigerant in the refrigerant circuit 10 satisfies the reference amount.

As shown in FIG. 6, first, when the first control unit 81 receives the instruction to perform the refrigerant amount detection operation, it starts the refrigerant amount detection control (step S1).

Next, the first control unit 81 (specifically, the first CPU 81a) determines whether the cooling operation is being performed (step S2). If the cooling operation is not performed in step S2, the refrigerant amount detection control is ended (step S9). On the other hand, in step S2, when the cooling operation is being performed, the refrigerant amount detection operation is started.

Specifically, the first valve V1 is opened (step S3). As a result, as shown in FIG. 4 , the refrigerant bypasses the first heat exchanger 24 and flows through the first flow path P1 that connects the discharge side of the compressor 21 and the receiver 26 . Therefore, the gas refrigerant discharged from the compressor 21 can be sent to the receiver 26 via the first flow path P<b>1 that bypasses the first heat exchanger 24 . Thus, the liquid refrigerant in the receiver 26 is pushed out to the refrigerant circuit 10, and the receiver 26 is filled with gas refrigerant.

In this way, in this step S3, the liquid refrigerant in the receiver 26 is discharged. In this operation, the following operations are performed. Gas refrigerant discharged from the compressor 21 is sent to the receiver 26 through the first flow path P1. The liquid refrigerant discharged from the receiver 26 flows out of the heat source unit 2 via the supercooling heat exchanger 29, the third valve V3, the check valve V7 and the closing valve 31. Refrigerant flowing out of the heat source unit 2 is sent to the utilization unit 5 via the connecting pipe 6 . The refrigerant sent to the usage unit 5 flows out of the usage unit 5 via the usage side expansion valve 51 and the second heat exchanger 52 . Refrigerant flowing out from the utilization unit 5 is sent to the heat source unit 2 via the communication pipe 7, and is again supplied to the compressor 21 via the stop valve 32, the four-way switching valve 22, the check valve V8, and the accumulator 23. is inhaled into

Next, it is determined whether or not the liquid refrigerant in the receiver 26 has been discharged (step S4). In step S4 of the present embodiment, as shown in FIG. 6, it is determined whether or not the degree of supercooling is less than the first value. Here, the first control unit 81 controls the degree of supercooling at the outlet of the supercooling heat exchanger 29, which is the temperature difference between the condensation temperature of the refrigerant in the supercooling heat exchanger 29 and the outlet temperature of the supercooling heat exchanger 29. Use f(HP)-TL.

More specifically, the first control unit 81 controls the discharge pressure HP of the compressor 21 detected by the discharge pressure sensor 42 and the pressure of the supercooling heat exchanger 29 detected by the supercooling heat exchanger outlet temperature sensor 47. Outlet temperature TL is acquired. Then, the obtained discharge pressure HP is converted into the saturation temperature f (HP), and the degree of supercooling f (HP), which is the temperature difference obtained by subtracting the outlet temperature TL of the supercooling heat exchanger 29 from this saturation temperature f (HP) - Calculate TL. In this embodiment, the first control unit 81 determines whether or not the degree of supercooling f(HP)-TL is less than the first value. The first value is, for example, 1, but can be set arbitrarily.

In step S4, if the degree of supercooling f(HP)-TL is greater than or equal to the first value, that state is maintained. On the other hand, in step S4, if the subcooling degree f(HP)-TL is less than the first value, it is determined that the liquid refrigerant in the receiver 26 has been pushed out and the gas refrigerant is filled.

Next, the second valve V2 is opened and the degree of opening of the third valve V3 is decreased (step S5). The opening operation of the second valve V2 and the operation of throttling the third valve V3 in step S5 are performed substantially simultaneously.

By opening the second valve V2, as shown in FIG. 5, the refrigerant bypasses the receiver 26 and flows from the first heat exchanger 24 to the second flow path P2. As a result, sending the refrigerant to the receiver 26 can be suppressed. In this embodiment, in step S5, sending the refrigerant to the receiver 26 and the subcooling heat exchanger 29 is suppressed.

Also, by reducing the degree of opening of the third valve V3, it is possible to prevent the density of the liquid refrigerant from becoming too low.

Thus, in this step S5, an operation for determining the amount of refrigerant in the refrigerant circuit 10 is performed. In this operation, the following operations are performed. The gas refrigerant discharged from the compressor 21 is sent to the second flow path P2 via the check valve V9, the four-way switching valve 22 and the first heat exchanger 24. Then, it flows out of the heat source unit 2 via the second valve V2, the check valve V7 and the closing valve 31. Refrigerant flowing out of the heat source unit 2 is sent to the utilization unit 5 via the connecting pipe 6 . The refrigerant sent to the usage unit 5 flows out of the usage unit 5 via the usage side expansion valve 51 and the second heat exchanger 52 . Refrigerant flowing out from the utilization unit 5 is sent to the heat source unit 2 via the communication pipe 7, and is again supplied to the compressor 21 via the stop valve 32, the four-way switching valve 22, the check valve V8, and the accumulator 23. is inhaled into

Next, it is determined whether or not the amount of refrigerant in the refrigerant circuit 10 satisfies the reference amount (step S6). In step S6 of the present embodiment, as shown in FIG. 6, it is determined whether or not the degree of supercooling is less than the second value. Here, the first control unit 81 controls subcooling, which is the temperature difference between the condensation temperature of the refrigerant in the first heat exchanger 24 used as a condenser and the outlet temperature Tcl of the first heat exchanger 24 used as a condenser. The degree f(HP)-Tcl is used.

More specifically, the first control unit 81 controls the discharge pressure HP of the compressor 21 detected by the discharge pressure sensor 42 and the pressure of the first heat exchanger 24 detected by the first heat exchanger outlet temperature sensor 46. Obtain the outlet temperature Tcl. Then, the obtained discharge pressure HP is converted into the saturation temperature f (HP), and the degree of supercooling f (HP), which is the temperature difference obtained by subtracting the outlet temperature Tcl of the first heat exchanger 24 from this saturation temperature f (HP) - Calculate Tcl. In this embodiment, the first control unit 81 determines whether or not the degree of supercooling f(HP)-Tcl is equal to or greater than the second value. The second value is, for example, 3, but can be set arbitrarily.

If the subcooling degree f(HP)-Tcl is equal to or greater than the second value in step S6, the first control unit 81 determines that the amount of refrigerant in the refrigerant circuit 10 is normal (step S7). On the other hand, if the subcooling degree f(HP)-Tcl is less than the second value in step S6, the first control unit 81 determines that the amount of refrigerant in the refrigerant circuit 10 is abnormal (step S8 ).
Here, if it is determined in step S8 that the amount of refrigerant is abnormal, the amount of refrigerant in the refrigerant circuit 10 does not meet the reference amount, so that the occurrence of refrigerant leakage is notified.

When the amount of refrigerant in the refrigerant circuit 10 is detected in steps S7 and S8, the refrigerant amount detection control ends (step S9). Such a refrigerant amount detection operation may be performed irregularly, but is performed periodically in the present embodiment. As a periodical operation, for example, the refrigerant amount detection operation is performed once a day.

(3) Features (3-1)
As described above, the refrigeration apparatus 1 and the heat source unit 2 according to the present embodiment include the compressor 21, the first heat exchanger 24, the receiver 26, the first flow path P1, the first valve V1, Prepare. Compressor 21 compresses the refrigerant. The first heat exchanger 24 is used as a refrigerant condenser. The receiver 26 stores the refrigerant discharged from the first heat exchanger 24 during normal operation using the first heat exchanger 24 as a condenser. The first flow path P1 bypasses the first heat exchanger 24 and connects the discharge side of the compressor 21 and the receiver 26 . The first valve V1 opens and closes the first flow path P1. During the refrigerant amount detection operation for detecting the amount of refrigerant in the refrigerant circuit 10, the first valve V1 is opened.

Here, since the first valve V1 is opened during the refrigerant amount detection operation, as shown in FIG. , can be sent to the receiver 26 . As a result, the liquid refrigerant in the receiver 26 is pushed out to the refrigerant circuit 10, and the refrigerant amount detection operation can be performed in a state where the receiver 26 is filled with gas refrigerant as shown in FIG. Therefore, as shown in FIG. 4, even if the high-temperature liquid refrigerant is discharged, the receiver 26 is filled with the high-temperature gas refrigerant when performing the refrigerant amount detection operation, so that the high-temperature state can be maintained. Therefore, even if the frequency of the refrigerant amount detection operation is increased and the frequency of switching between the normal operation and the refrigerant amount detection operation is high, the temperature change of the receiver 26 can be reduced. It is possible to reduce phenomena such as the effect of thermal stress on the As a result, the normal operation and the refrigerant amount detection operation can be performed without increasing the resistance of the receiver 26 .

Also, even if the refrigerant amount detection operation is performed, the second heat exchanger 52 can continue to cool the inside of the refrigerator, so it is possible to suppress the deterioration of the cooling capacity.

(3-2)
The refrigerating apparatus 1 and the heat source unit 2 of this embodiment further include a first control section 81 . The first control unit 81 closes the first valve V1 during normal operation, and opens the first valve V1 during refrigerant amount detection operation.

Here, during the cooling operation using the first heat exchanger 24 as a condenser, the first valve V1 is closed and the first flow path P1 is not used. On the other hand, during the refrigerant amount determination operation, the first valve V1 is opened and the first flow path P1 is used. Therefore, normal operation and refrigerant amount detection operation can be appropriately performed.

(3-3)
The refrigerating apparatus 1 and the heat source unit 2 of this embodiment further include a second flow path P2. The second flow path P2 is connected to the first heat exchanger 24 and bypasses the receiver 26 . During the refrigerant amount detection operation, the refrigerant flows from the first heat exchanger 24 to the second flow path P2.

Here, it is possible to reduce the amount of refrigerant sent to the receiver 26 by causing the refrigerant to flow through the second flow path P2 during the refrigerant amount detection operation. Therefore, even if the operation for determining the amount of refrigerant shown in FIG. 5 is performed after the operation for discharging the liquid refrigerant in the receiver 26 shown in FIG. Therefore, in the refrigerant amount detection operation, it is possible to improve the accuracy of detecting the refrigerant amount.

(3-4)
The refrigerating apparatus 1 and the heat source unit 2 of this embodiment further include a second valve V2. The second valve V2 opens and closes the second flow path P2.

Here, the refrigerant can flow through the second flow path P2 by opening the second valve V2 during the refrigerant amount detection operation. On the other hand, during normal operation, by closing the second valve V2, it is possible to suppress the refrigerant from flowing through the second flow path P2. Therefore, normal operation and refrigerant amount detection operation can be performed more appropriately.

(3-5)
The refrigerating device 1 and the heat source unit 2 of this embodiment further include a third valve V3. The third valve V3 is arranged downstream of the receiver 26 during normal operation. During the refrigerant amount detection operation, the degree of opening of the third valve V3 is reduced.

Here, by reducing the degree of opening of the third valve V3 arranged downstream of the receiver 26 during the refrigerant amount detection operation, it is possible to prevent the density of the liquid refrigerant from becoming too low.

(3-6)
The refrigerating apparatus 1 and the heat source unit 2 of this embodiment further include a second flow path P2. The second flow path P2 also bypasses the receiver 26 and the third valve V3.

Here, the refrigerant can flow through the second flow path P2 that bypasses the receiver 26 and the third valve V3 during the refrigerant amount detection operation. Therefore, the refrigerant amount detection operation can be performed while preventing the density of the liquid refrigerant from becoming too low.

(3-7)
In the refrigerating apparatus 1 and the heat source unit 2 of this embodiment, after the first valve V1 opens, the second valve V2 opens and the opening degree of the third valve V3 decreases during the refrigerant amount detection operation.

Here, as shown in FIG. 4, the liquid refrigerant in the receiver 26 is pushed out by opening the first valve V1, and then, as shown in FIG. It is possible to suppress accumulation of the liquid refrigerant, and it is possible to suppress the density of the liquid refrigerant from becoming too low due to the reduction in the degree of opening of the third valve V3. Therefore, the amount of refrigerant can be detected while maintaining the density of the liquid refrigerant.

(3-8)
In the refrigerating apparatus 1 and the heat source unit 2 of the present embodiment, the refrigerant amount detection operation is performed using the condenser outlet temperature when the first heat exchanger 24 is used as a condenser, the high pressure of the refrigerant circuit 10, the low pressure of the refrigerant circuit 10, the receiver At least one of the outlet temperature of 26, the outside air temperature, the evaporation temperature, and the rotation speed of the compressor 21 is used to detect the amount of refrigerant.

Here, the refrigerant amount is detected using at least one of the condenser outlet temperature, high pressure, low pressure, receiver 26 outlet temperature, outside air temperature, evaporation temperature, and compressor 21 rotation speed. can be easily realized.

In addition, in the refrigerating apparatus 1 and the heat source unit 2 further including the supercooling heat exchanger 29, the temperature before and after the supercooling heat exchanger 29 may be used for the refrigerant amount detection operation.

(3-9)
A refrigerating apparatus 1 of this embodiment includes a heat source unit 2 and a utilization unit 5 . The utilization unit 5 is connected to the heat source unit 2 and includes a second heat exchanger 52 .

Here, since the heat source unit 2 is provided, it is possible to realize the refrigerating apparatus 1 that reduces phenomena such as dew condensation on the outer shell of the receiver 26 and thermal stress acting on the piping joints even if the frequency of the refrigerant amount detection operation is increased. .

(4) Modification (4-1) Modification A
In the above-described embodiment, the refrigerant amount detection operation has been described by exemplifying the operation of performing the refrigerant amount detection operation after the cooling operation as the normal operation has been performed for a predetermined period of time, but the operation is not limited to this. The refrigerant amount detection operation of the present disclosure is an operation that stabilizes the state of the refrigerant circulating in the refrigerant circuit 10 and fills the refrigerant circuit 10 with refrigerant until the amount of refrigerant in the refrigerant circuit 10 reaches a target amount. may be applied to

In this way, the refrigerating apparatus 1 and the heat source unit 2 of the present disclosure perform the refrigerant amount detection operation by detecting whether or not the amount of refrigerant in the refrigerant circuit 10 satisfies the reference amount, and the refrigerant leakage detection operation for detecting whether the amount of refrigerant in the refrigerant circuit 10 satisfies the reference amount. A refrigerant charging operation for charging can be performed.

(4-2) Modification B
In the above embodiment, in the step of determining whether or not the liquid refrigerant in the receiver 26 has been discharged during the refrigerant amount detection operation (step S4), the degree of supercooling at the outlet of the supercooling heat exchanger 29 is used for determination. but not limited to. In the refrigerant amount detection operation of the present disclosure, another index may be used in step S4, and the liquid level of the liquid refrigerant stored in the receiver 26 may be detected.

(4-3) Modification C
In the above embodiment, the index detected by the heat source unit 2 is used to detect the amount of refrigerant during the refrigerant amount detection operation, but the present invention is not limited to this. The refrigerant amount detection operation may use the index detected by the usage unit 5 or may use the index detected by the heat source unit 2 and the usage unit 5 . In this modification, the refrigerant amount is detected by using the opening degree of the user-side expansion valve 51 of the user unit 5, the outlet temperature of the second heat exchanger 52, and the like.

(4-4) Modification D
In the above embodiment, the refrigeration apparatus 1 including one usage unit 5 was described as an example, but the present invention is not limited to this. A refrigeration apparatus of the present disclosure may comprise more than one utilization unit. In this case, the capacity of each usage unit may be the same or different.

(4-5) Modification E
Although the refrigerating apparatus 1 including the supercooling circuit has been described as an example in the above embodiment, the present invention is not limited to this. In this modification, the branch pipe 27, the supercooling expansion valve 28 and the supercooling heat exchanger 29 are omitted.

(4-6) Modification F
In the above embodiment, the refrigeration apparatus 1 capable of cooling operation and heating operation has been described as an example, but the present invention is not limited to this. In this modified example, the refrigeration system is exclusively for cooling operation.

Although embodiments of the present disclosure have been described above, it will be appreciated that various changes in form and detail may be made without departing from the spirit and scope of the present disclosure as set forth in the appended claims. .

Reference Signs List 1: Refrigerating device 2: Heat source unit 5: Utilization unit 10: Refrigerant circuit 21: Compressor 24: First heat exchanger 26: Receiver 52: Second heat exchanger 81: First control unit (control unit)
P1: first flow path P2: second flow path V1: first valve V2: second valve V3: third valve

JP 2015-75259 A

Claims

A heat source unit (2) that constitutes a refrigerant circuit (10) that performs a refrigeration cycle by being connected to a utilization unit (5),
a compressor (21) for compressing a refrigerant;
a first heat exchanger (24) used as a condenser for the refrigerant;
a receiver (26) for storing the refrigerant discharged from the first heat exchanger during normal operation using the first heat exchanger as a condenser;
a first flow path (P1) connecting the discharge side of the compressor and the receiver, bypassing the first heat exchanger;
a first valve (V1) that opens and closes the first flow path;
with
the first valve opens during a refrigerant amount detection operation for detecting the amount of refrigerant in the refrigerant circuit;
heat source unit.
A control unit (81) that closes the first valve during the normal operation and opens the first valve during the refrigerant amount detection operation,
The heat source unit according to claim 1.
further comprising a second flow path (P2) connected to the first heat exchanger and bypassing the receiver;
During the refrigerant amount detection operation, the refrigerant flows from the first heat exchanger to the second flow path,
The heat source unit according to claim 1 or 2.
Further comprising a second valve (V2) that opens and closes the second flow path,
The heat source unit according to claim 3.
Further comprising a third valve (V3) arranged downstream of the receiver during normal operation,
The degree of opening of the third valve decreases during the refrigerant amount detection operation,
A heat source unit according to any one of claims 1 to 4.
further comprising a second flow path (P2) connected to the first heat exchanger and bypassing the receiver;
the second flow path bypasses the third valve;
The heat source unit according to claim 5.
a second flow path (P2) connected to the first heat exchanger and bypassing the receiver;
a second valve (V2) for opening and closing the second flow path;
further comprising
During the refrigerant amount detection operation, the second valve opens after the first valve opens, and the opening degree of the third valve decreases.
The heat source unit according to claim 5 or 6.
The refrigerant amount detection operation includes a condenser outlet temperature when the first heat exchanger is used as a condenser, a high pressure of the refrigerant circuit, a low pressure of the refrigerant circuit, an outlet temperature of the receiver, an outside air temperature, an evaporation temperature, and Detecting the amount of refrigerant using at least one of the rotation speeds of the compressor,
The heat source unit according to any one of claims 1-7.
a heat source unit according to any one of claims 1 to 8;
a utilization unit connected to the heat source unit and including a second heat exchanger;
comprising
A refrigerator (1).