JP7397286B2 - Refrigeration cycle equipment - Google Patents

Description

The present invention relates to a refrigeration cycle device.

Patent Document 1 (International Publication No. 2018/062485) describes that in a refrigeration system having a refrigerant circuit that flows a gas-liquid two-phase refrigerant through a liquid-side refrigerant connection pipe, the longer the liquid-side refrigerant connection pipe is, the more the liquid A refrigerant amount determination method and a determination device are disclosed for determining the amount of refrigerant to be filled into a refrigerant circuit so that the amount of refrigerant per unit length of a side refrigerant communication pipe is increased. Further, Patent Document 1 states that whether the state of the refrigerant after being depressurized in the outdoor expansion valve becomes a liquid refrigerant or a gas-liquid two-phase refrigerant depends on the length of the liquid-side refrigerant communication piping to be constructed. It is disclosed that the amount varies depending on the installed refrigeration equipment.

According to the method and device for determining the amount of refrigerant disclosed in Patent Document 1, it is possible to determine the appropriate amount of refrigerant to be charged depending on the length of the refrigerant communication pipe. However, Patent Document 1 does not mention refrigerant leakage. In order to detect refrigerant leaks at an early stage, it is desired to improve the accuracy of detecting refrigerant leaks.

The refrigeration cycle device according to the first aspect is a refrigeration cycle device that detects that the amount of refrigerant in the refrigerant circuit is changing, and includes a heat source side unit, a usage side unit, a first communication pipe, and a second communication pipe. The heat source side unit includes a compressor, a heat source side heat exchanger, and a heat source side expansion mechanism. The user-side unit includes a plurality of user-side heat exchangers and a plurality of user-side expansion mechanisms. The first connecting pipe connects the heat source side unit and the usage side unit. The second connecting pipe connects the heat source side unit and the user side unit, and during the first operation in which the user side heat exchanger functions as an evaporator, the refrigerant having a lower pressure than the refrigerant in the first connecting pipe connects the heat source side unit and the user side unit. Pass. During the first operation, at least the degree of pressure reduction of the heat source side expansion mechanism is adjusted to maintain the refrigerant in the first communication pipe in a gas-liquid two-phase state.

In the refrigeration cycle device according to the first aspect, during the first operation, the refrigerant in the first communication pipe is maintained in a gas-liquid two-phase state. This reduces the amount of refrigerant flowing through the first communication pipe during the first operation. Therefore, even if the amount of refrigerant changes is small, it will affect the first operation, so refrigerant amount detection processing that detects changes in the amount of refrigerant in the refrigerant circuit must be performed with high accuracy. I can do it. Since refrigerant leakage can be detected based on changes in the amount of refrigerant, the accuracy of detecting refrigerant leakage can be improved.

The refrigeration cycle device according to the second aspect is the refrigeration cycle device according to the first aspect, in which the heat source side expansion mechanism has a heat source side expansion valve whose opening degree can be changed. By adjusting the opening degree of the heat source side expansion valve, the degree of pressure reduction of the heat source side expansion mechanism is adjusted.

In the refrigeration cycle device according to the second aspect, the refrigerant in the first communication pipe can be easily maintained in a gas-liquid two-phase state by adjusting the opening degree of the heat source side expansion valve.

The refrigeration cycle device according to the third aspect is the refrigeration cycle device according to the first or second aspect, and the heat source side expansion mechanism has a heat source side expansion valve whose opening degree can be changed. Changes in the amount of refrigerant are detected using an index using the opening degree of the heat source side expansion valve.

In the refrigeration cycle device according to the third aspect, the accuracy of the refrigerant amount detection process can be further improved by using the index using the opening degree of the heat source side expansion valve.

The refrigeration cycle device according to the fourth aspect is the refrigeration cycle device according to the first to third aspects, and further includes a determination unit that determines that the refrigerant has leaked when it is detected that the amount of refrigerant has changed.

In the refrigeration cycle device according to the fourth aspect, when a change in the amount of refrigerant is detected, it is determined that the refrigerant has leaked, so that refrigerant leakage can be detected at an early stage.

The refrigeration cycle device according to the fifth aspect is the refrigeration cycle device according to the first to fourth aspects, and further includes an accumulation section that accumulates data of the first operation.

In the refrigeration cycle device according to the fifth aspect, refrigerant amount detection processing can be performed from the accumulated data.

A refrigeration cycle device according to a sixth aspect is a refrigeration cycle device that detects a change in the amount of refrigerant in a refrigerant circuit, and includes a heat source side unit, a usage side unit, a first communication pipe, and a second communication pipe. The heat source side unit includes a compressor, a heat source side heat exchanger, and a heat source side expansion mechanism. The user-side unit includes a plurality of user-side heat exchangers and a plurality of user-side expansion mechanisms. The first connecting pipe connects the heat source side unit and the usage side unit. The second connecting pipe connects the heat source side unit and the user side unit, and during the second operation in which the user side heat exchanger functions as a condenser, a refrigerant having a higher pressure than the refrigerant in the first connecting pipe connects the heat source side unit and the user side unit. Pass. During the second operation, at least the degree of pressure reduction of the user-side expansion mechanism is adjusted to maintain the refrigerant in the first communication pipe in a gas-liquid two-phase state.

In the refrigeration cycle device according to the sixth aspect, the refrigerant in the first communication pipe is maintained in a gas-liquid two-phase state during the second operation. This reduces the amount of refrigerant flowing through the first communication pipe during the second operation. Therefore, even if the amount of refrigerant changes is small, it will affect the second operation, so refrigerant amount detection processing that detects changes in the amount of refrigerant in the refrigerant circuit must be performed with high accuracy. I can do it. Since refrigerant leakage can be detected based on changes in the amount of refrigerant, the accuracy of detecting refrigerant leakage can be improved.

1 is a schematic configuration diagram of a refrigeration cycle device according to an embodiment of the present disclosure. FIG. 1 is a block diagram schematically showing a refrigeration cycle device of the present disclosure. FIG. 2 is a block diagram showing a control system of the refrigeration cycle device of the present disclosure. 3 is a flowchart illustrating a refrigerant leak determination method according to an embodiment of the present disclosure.

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

(1) Overall Configuration As shown in FIG. 1, a refrigeration cycle device 1 according to an embodiment of the present disclosure detects that the amount of refrigerant in the refrigerant circuit 10 is changing.

The refrigeration cycle device 1 of this embodiment is an air conditioner that cools and heats the interior of a building using a vapor compression refrigeration cycle. Here, the first operation in which the user-side heat exchangers 52a and 52b function as evaporators is referred to as a cooling operation, and the second operation in which the user-side heat exchangers 52a and 52b function as condensers is referred to as a heating operation. However, the refrigeration cycle device 1 is not limited to an air conditioner, and may be, for example, a water heater.

As shown in FIGS. 1 and 2, the refrigeration cycle device 1 mainly includes a heat source side unit 2, usage side units 5a and 5b, a first connecting pipe 6, a second connecting pipe 7, and an accumulation section 60. , and a determination unit 70.

As shown in FIG. 1, a refrigerant circuit 10 is configured by connecting the heat source side unit 2 and the usage side units 5a, 5b via the first communication pipe 6 and the second communication pipe 7. The refrigerant circuit 10 includes a compressor 21 of the heat source side unit 2, a heat source side heat exchanger 24, an expansion mechanism and a switching mechanism 23, a usage side heat exchanger 52a, 52b of the usage side units 5a, 5b, and an expansion mechanism. Mainly includes.

The refrigerant circuit 10 is filled with, for example, a fluorocarbon-based refrigerant. Note that the refrigerant filled in the refrigerant circuit 10 of the present disclosure is not particularly limited.

(2) Detailed configuration (2-1) User-side units The user-side units 5a and 5b are installed indoors in a building or the like. The usage side units 5a and 5b are connected to the heat source side unit 2 via the first communication pipe 6 and the second communication pipe 7, and constitute a part of the refrigerant circuit 10.

Next, the configuration of the user-side units 5a and 5b will be explained. Note that since the user unit 5a and the user unit 5b have the same configuration, only the configuration of the user unit 5a will be explained here, and the configuration of the user unit 5b will be explained by referring to each part of the user unit 5a. The subscript "b" is added instead of the subscript "a" indicating that the description of each part will not be repeated.

The usage-side unit 5a mainly includes a usage-side expansion valve 51a, a usage-side heat exchanger 52a, a usage-side first refrigerant pipe 53a, a usage-side second refrigerant pipe 54a, and a usage-side fan 55a. ing.

The opening degree of the utilization side expansion valve 51a can be changed. By adjusting the opening degree of the usage-side expansion valve 51a, the degree of pressure reduction of the usage-side expansion valve 51a is adjusted. Specifically, the usage-side expansion valve 51a is an electric expansion valve whose opening degree can be adjusted to adjust the flow rate of the refrigerant flowing through the usage-side heat exchanger 52a. The usage-side expansion valve 51a is provided in the usage-side first refrigerant pipe 53a.

The user-side heat exchanger 52a exchanges heat between the refrigerant and indoor air. The user-side heat exchanger 52a functions as a refrigerant evaporator to cool indoor air during cooling operation, and functions as a refrigerant condenser to heat indoor air during heating operation.

The user-side first refrigerant pipe 53a connects the user-side heat exchanger 52a and the first communication pipe 6. Gas-liquid two-phase refrigerant flows through the inlet of the first user-side refrigerant pipe 53a. The user-side second refrigerant pipe 54a connects the user-side heat exchanger 52a and the second communication pipe 7.

The user-side fan 55a sucks indoor air into the user-side unit 5a, exchanges heat with the refrigerant in the user-side heat exchanger 52a, and then supplies the air indoors as supply air. The user-side fan 55a supplies indoor air to the user-side heat exchanger 52a as a heating source or cooling source for the refrigerant flowing through the user-side heat exchanger 52a.

The user unit 5a is provided with various sensors. Specifically, the usage-side unit 5a includes a usage-side heat exchanger inlet temperature sensor 56a and a usage-side heat exchanger outlet temperature sensor 57a.

The usage-side heat exchanger inlet temperature sensor 56a detects the temperature TH2 of the refrigerant on the first communication pipe 6 side of the usage-side heat exchanger 52a. The user-side heat exchanger inlet temperature sensor 56a is an evaporator inlet temperature sensor that measures the evaporator inlet temperature when the user-side heat exchanger 52a is used as an evaporator. The user-side heat exchanger inlet temperature sensor 56a is a condenser outlet temperature sensor that measures the outlet temperature of the condenser when the user-side heat exchanger 52a is used as a condenser.

The usage-side heat exchanger outlet temperature sensor 57a detects the temperature TH3 of the refrigerant on the second communication pipe 7 side of the usage-side heat exchanger 52a. The user-side heat exchanger outlet temperature sensor 57a is an evaporator outlet temperature sensor that measures the outlet temperature of the evaporator when the user-side heat exchanger 52a is used as an evaporator. The user-side heat exchanger outlet temperature sensor 57a is a condenser inlet temperature sensor that measures the inlet temperature of the condenser when the user-side heat exchanger 52a is used as a condenser.

The user unit 5a includes a user control section 58a that controls the operation of each component of the user unit 5a. The user-side control unit 58a includes a microcomputer, memory, etc. provided for controlling the user-side unit 5a, and includes a remote controller (not shown) for individually operating the user-side unit 5a. It is possible to exchange control signals and the like between the heat source unit 2 and the heat source unit 2 via the transmission line 8a.

(2-2) Heat source side unit The heat source side unit 2 is installed outdoors in a building or the like. The heat source side unit 2 is connected to the usage side units 5a and 5b via the first connecting pipe 6 and the second connecting pipe 7, and constitutes a part of the refrigerant circuit 10. Note that in this embodiment, two usage-side units 5a and 5b are connected in parallel to each other, but the number of usage-side units may be three or more.

Next, the configuration of the heat source side unit 2 will be explained. The heat source side unit 2 mainly includes a compressor 21, a switching mechanism 23, a heat source side heat exchanger 24, a heat source side first expansion valve 25, a heat source side first refrigerant pipe 26, a suction pipe 27, and an accumulator. 28, the discharge pipe 29, the heat source side second refrigerant pipe 30, the heat source side third refrigerant pipe 31, the first closing valve 32, the second closing valve 33, the heat source side fan 34, and the bypass pipe 35. , a supercooling heat exchanger side expansion valve 38, a supercooling heat exchanger 39, and a heat source side second expansion valve 40. The heat source side expansion mechanism includes a heat source side first expansion valve 25, a supercooling heat exchanger side expansion valve 38, and a heat source side second expansion valve 40.

The compressor 21 is a device that compresses low pressure refrigerant until it becomes high pressure. Here, as the compressor 21, a hermetic structure compressor in which a positive displacement compression element (not shown) such as a rotary type or a scroll type is rotationally driven by a compressor motor 22 is used. Further, here, the rotation speed of the compressor motor 22 can be controlled by an inverter or the like, and thereby the capacity of the compressor 21 can be controlled.

The switching mechanism 23 is a four-way switching valve that can switch the flow direction of the refrigerant in the refrigerant circuit 10. During cooling operation, the switching mechanism 23 connects the suction side of the compressor 21 to the second communication pipe 7 through the suction pipe 27 and the heat source side third refrigerant pipe 31, and connects the discharge side of the compressor 21 to the discharge pipe 29. It is a mechanism that can be switched to communicate with the heat source side heat exchanger 24 through the heat source side second refrigerant pipe 30. Therefore, the refrigerant circuit 10 is a cooling cycle in which the heat source side heat exchanger 24 functions as a refrigerant condenser and the user side heat exchangers 52a and 52b function as refrigerant evaporators by switching the switching mechanism 23. state (see the solid line of the switching mechanism 23 in FIG. 1). Furthermore, during heating operation, the switching mechanism 23 connects the suction side of the compressor 21 to the heat source side heat exchanger 24 through the suction pipe 27 and the heat source side second refrigerant pipe 30, and connects the discharge side of the compressor 21 to the heat source side heat exchanger 24. It is a mechanism that can be switched to communicate with the second communication pipe 7 through the discharge pipe 29 and the third heat source side refrigerant pipe 31. Therefore, by switching the switching mechanism 23, the refrigerant circuit 10 causes the heat source side heat exchanger 24 to function as a refrigerant evaporator, and causes the user side heat exchangers 52a and 52b to function as a refrigerant condenser. It is possible to switch to the heating cycle state (see the broken line of the switching mechanism 23 in FIG. 1). The switching mechanism 23 is not limited to a four-way switching valve, but may be configured to switch the flow direction of the refrigerant as described above by combining a plurality of electromagnetic valves and refrigerant pipes. Good too.

The heat source side heat exchanger 24 exchanges heat between the refrigerant and outdoor air. The heat source side heat exchanger 24 functions as a refrigerant condenser during cooling operation, and functions as a refrigerant evaporator during heating operation. The heat source side heat exchanger 24 has a gas side end connected to the heat source side second refrigerant pipe 30, and an opposite end connected to the heat source side first refrigerant pipe 26.

The opening degree of the heat source side first expansion valve 25 can be changed. By adjusting the opening degree of the heat source side first expansion valve 25, the degree of pressure reduction of the heat source side first expansion valve 25 is adjusted. Specifically, the heat source side first expansion valve 25 is an electric expansion valve whose opening degree can be adjusted to adjust the flow rate of the refrigerant flowing through the heat source side heat exchanger 24. The heat source side first expansion valve 25 is provided in the heat source side first refrigerant pipe 26.

The heat source side first refrigerant pipe 26 connects the heat source side heat exchanger 24 and the first communication pipe 6. Suction pipe 27 connects switching mechanism 23 and the suction side of compressor 21 .

The suction pipe 27 is provided with an accumulator 28 that temporarily stores refrigerant sucked into the compressor 21. In other words, the accumulator 28 stores surplus refrigerant.

The discharge pipe 29 connects the discharge side of the compressor 21 and the switching mechanism 23 . The heat source side second refrigerant pipe 30 connects the switching mechanism 23 and the heat source side heat exchanger 24. The heat source side third refrigerant pipe 31 connects the second communication pipe 7 and the switching mechanism 23. A first closing valve 32 is provided at a connection portion of the first refrigerant pipe 26 on the heat source side with the first communication pipe 6 . A second closing valve 33 is provided at the connection portion of the heat source side third refrigerant pipe 31 with the second communication pipe 7 . The first closing valve 32 and the second closing valve 33 are valves that are manually opened and closed.

The heat source side fan 34 sucks outdoor air into the heat source side unit 2, exchanges heat with the refrigerant in the heat source side heat exchanger 24, and then discharges it outside the heat source side unit 2. The heat source side fan 34 supplies outdoor air to the heat source side heat exchanger 24 as a cooling source or heating source for the refrigerant flowing through the heat source side heat exchanger 24 .

Moreover, a bypass pipe 35 is connected to the heat source side first refrigerant pipe 26, and a subcooling heat exchanger 39 is provided. The bypass pipe 35 is a refrigerant pipe that branches part of the refrigerant flowing through the heat source side first refrigerant pipe 26 and returns it to the compressor 21 . The subcooling heat exchanger 39 cools the refrigerant flowing through the heat source side first refrigerant pipe 26 with the low-pressure refrigerant flowing through the bypass pipe 35 . The subcooling heat exchanger 39 is provided in the heat source side first refrigerant pipe 26 closer to the first communication pipe 6 than the heat source side first expansion valve 25 .

Bypass pipe 35 connects supercooling heat exchanger 39 and compressor 21 . The bypass pipe 35 is a refrigerant return pipe that sends the refrigerant branched from the heat source side first refrigerant pipe 26 to the suction side of the compressor 21. The bypass pipe 35 has a refrigerant return inlet pipe 36 and a refrigerant return outlet pipe 37.

The refrigerant return inlet pipe 36 is a refrigerant pipe that branches a part of the refrigerant flowing through the heat source side first refrigerant pipe 26 and sends it to the inlet of the subcooling heat exchanger 39 on the bypass pipe 35 side. The refrigerant return inlet pipe 36 is connected to the heat source side first expansion valve 25 and the subcooling heat exchanger 39.

The refrigerant return inlet pipe 36 is provided with a supercooling heat exchanger side expansion valve 38 that adjusts the flow rate of the refrigerant flowing through the bypass pipe 35 . The supercooling heat exchanger side expansion valve 38 reduces the pressure of the refrigerant that flows through the bypass pipe 35 and enters the supercooling heat exchanger 39 . The opening degree of the supercooling heat exchanger side expansion valve 38 can be changed. Specifically, the supercooling heat exchanger side expansion valve 38 is an electric expansion valve whose opening degree can be adjusted to adjust the flow rate of the refrigerant flowing through the bypass pipe 35.

The refrigerant return outlet pipe 37 is a refrigerant pipe that sends the refrigerant from the outlet on the bypass pipe 35 side of the supercooling heat exchanger 39 to the suction pipe 27 connected to the suction side of the compressor 21 .

Note that the bypass pipe 35 may be a refrigerant pipe that sends the refrigerant not to the suction side of the compressor 21 but to the middle of the compression stroke of the compressor 21.

The opening degree of the heat source side second expansion valve 40 can be changed. By adjusting the opening degree of the heat source side second expansion valve 40, the degree of pressure reduction of the heat source side second expansion valve 40 is adjusted. Specifically, the heat source side second expansion valve 40 is an electric expansion valve whose opening degree can be adjusted to adjust the flow rate of the refrigerant flowing through the subcooling heat exchanger 39. The heat source side second expansion valve 40 is provided between the subcooling heat exchanger 39 and the first closing valve 32.

The heat source side unit 2 is provided with various sensors. Specifically, the heat source side unit 2 includes a suction pressure sensor 41, a suction temperature sensor 42, a discharge pressure sensor 43, a discharge temperature sensor 44, a heat source side heat exchanger outlet temperature sensor 45, and a subcooling heat exchanger. It has a chamber outlet temperature sensor 46. A suction pressure sensor 41 , a suction temperature sensor 42 , a discharge pressure sensor 43 , and a discharge temperature sensor 44 are provided around the compressor 21 of the heat source side unit 2 .

The suction pressure sensor 41 detects the suction pressure Lp of the compressor 21. The suction temperature sensor 42 detects the suction temperature Ts of the compressor 21. The discharge pressure sensor 43 detects the discharge pressure Pd of the compressor 21. The discharge temperature sensor 44 detects the discharge temperature Td of the compressor 21.

The heat source side heat exchanger outlet temperature sensor 45 is located closer to the heat source side heat exchanger 24 than the subcooling heat exchanger 39 in the heat source side first refrigerant pipe 26 (in FIG. side heat exchanger 24 side). The heat source side heat exchanger outlet temperature sensor 45 detects the temperature Tb of the refrigerant on the first communication pipe 6 side of the heat source side heat exchanger 24 . The heat source side heat exchanger outlet temperature sensor 45 is a condenser outlet temperature sensor that measures the outlet temperature Tb of the condenser when the heat source side heat exchanger 24 is used as a condenser. The heat source side heat exchanger outlet temperature sensor 45 is an evaporator inlet temperature sensor that measures the evaporator inlet temperature when the heat source side heat exchanger 24 is used as an evaporator.

The subcooling heat exchanger outlet temperature sensor 46 is provided in the refrigerant return outlet pipe 37. The supercooling heat exchanger outlet temperature sensor 46 measures the outlet temperature Tsh of the supercooling heat exchanger 39. Specifically, the subcooling heat exchanger outlet temperature sensor 46 detects the temperature Tsh of the refrigerant flowing through the exit of the subcooling heat exchanger 39 on the bypass pipe 35 side.

As shown in FIG. 2, the heat source side unit 2 further includes a data transmitter 47. The data transmitting section 47 transmits data during driving to a storage section 60, which will be described later. Here, the cooling operation data is transmitted to the storage unit 60.

As shown in FIGS. 1 to 3, the heat source side unit 2 further includes a heat source side control section 48 that controls the operation of each part constituting the heat source side unit 2. The heat source side control unit 48 includes a microcomputer, a memory, an inverter circuit for controlling the heat source side expansion valve, etc. provided for controlling the heat source side unit 2, and includes the use side units 5a, 5b. Control signals and the like can be exchanged with the user-side control units 58a and 58b via the transmission line 8a. In this way, the entire refrigeration cycle apparatus 1 is controlled by the user-side controllers 58a, 58b, the heat source-side controller 48, and the transmission line 8a connecting between the user-side controllers 58a, 58b and the heat source-side controller 48. A control section 8 that performs operational control is configured.

As shown in FIG. 3, the control unit 8 is connected to receive detection signals from various sensors 41 to 46, 56a, 56b, 57a, and 57b, and controls various devices based on these detection signals. , compressor 21, switching mechanism 23, heat source side fan 34, heat source side first expansion valve 25, heat source side second expansion valve 40, supercooling heat exchanger side expansion valve 38, usage side expansion valves 51a, 51b, usage side It is connected so that the fans 55a, 55b, etc. can be controlled. The control unit 8 is connected to a controller 15 that accepts various setting inputs from the user, and has a memory (not shown).

(2-3) Connecting pipe Returning to Figure 1, the first connecting pipe 6 and the second connecting pipe 7 are constructed on-site when installing an air conditioner equipped with a refrigerant circuit 10 at a building or other installation location. These are refrigerant pipes having various lengths and pipe diameters depending on installation conditions such as the installation location and the combination of the heat source side unit 2 and the use side units 5a, 5b.

The first connecting pipe 6 and the second connecting pipe 7 connect the heat source side unit 2 and the user side units 5a and 5b. Specifically, the first communication pipe 6 is located between the first usage-side refrigerant pipes 53a, 53b of the usage-side units 5a, 5b and the first closing valve 32. The second communication pipe 7 is located between the second usage-side refrigerant pipes 54a, 54b of the usage-side units 5a, 5b and the second closing valve 33.

During the first operation (cooling operation here) in which the user-side heat exchangers 52a and 52b function as evaporators, the second communication pipe 7 contains a refrigerant whose pressure is lower than that of the refrigerant in the first communication pipe 6. Pass. Also, during the second operation (heating operation here) in which the user-side heat exchangers 52a and 52b function as condensers, the second connection pipe 7 is filled with refrigerant having a higher pressure than the refrigerant in the first connection pipe 6. passes.

During the first operation, the degree of pressure reduction of at least the heat source side expansion mechanism (here, at least one of the heat source side first expansion valve 25 and the heat source side second expansion valve 40) is adjusted to Keeps the refrigerant in a gas-liquid two-phase state. Specifically, in order to maintain the refrigerant in the first communication pipe 6 in a gas-liquid two-phase state, the heat source side control unit 48 controls at least one of the heat source side first expansion valve 25 and the heat source side second expansion valve 40. By adjusting the opening degree of the heat source side expansion mechanism, the degree of pressure reduction of the heat source side expansion mechanism is adjusted. In the present embodiment, during cooling operation, the refrigerant flowing from the heat source side second expansion valve 40 disposed on the outlet side of the subcooling heat exchanger 39 toward each user side expansion valve 51a, 51b is brought into a gas-liquid two-phase state. keep.

Further, during the second operation, the degree of pressure reduction of at least the user-side expansion mechanism (here, the user-side expansion valves 51a, 51b) is adjusted to maintain the refrigerant in the first communication pipe 6 in a gas-liquid two-phase state. Specifically, in order to maintain the refrigerant in the first communication pipe 6 in a gas-liquid two-phase state, the usage-side expansion valves 51a, By adjusting the opening degree of 51b, the degree of pressure reduction of the user-side expansion mechanism is adjusted. In this embodiment, during heating operation, the refrigerant flowing from the usage-side expansion valves 51a, 51b toward the heat source-side second expansion valve 40 is maintained in a gas-liquid two-phase state.

(2-4) Accumulation Unit As shown in FIG. 2, the accumulation unit 60 accumulates cooling operation data. The storage unit 60 receives cooling operation data from the data transmission unit 47 of the heat source unit 2 . The storage unit 60 stores cooling operation data for detecting whether the amount of refrigerant is changing. In this embodiment, the storage unit 60 stores data regarding the opening degree of at least one of the heat source side first expansion valve 25 and the heat source side second expansion valve 40. The storage unit 60 also stores data regarding the total amount of refrigerant flowing through the refrigerant circuit 10 .

Note that the storage unit 60 may further store heating operation data.

(2-5) Determination Unit When the determination unit 70 detects that the amount of refrigerant is changing, it determines that the refrigerant has leaked. Here, in order to detect that the amount of refrigerant is changing, an index using the opening degree of at least one of the first expansion valve 25 on the heat source side and the second expansion valve 40 on the heat source side during cooling operation is used. In other words, the determination unit 70 detects that the amount of refrigerant is changing based on an index using the opening degree of at least one of the heat source side first expansion valve 25 and the heat source side second expansion valve 40. During heating operation, the determination unit 70 detects that the amount of refrigerant is changing based on an index using the opening degrees of the usage-side expansion valves 51a and 51b.

The index using the opening degree of the heat source side expansion valve and the index using the opening degree of the utilization side expansion valves 51a and 51b are for evaluating whether the amount of refrigerant is changing. These include the value of the opening itself, the rate of change in the opening degree, the integral value of the opening degree, etc. Regarding the value of the opening degree itself, when the opening degree is larger than the threshold value, the determination unit 70 detects that the amount of refrigerant has changed. Regarding the rate of change in the opening degree, when the change in the opening degree over a predetermined period of time is greater than a threshold value, the determination unit 70 detects that the amount of refrigerant has changed. Regarding the integral value of the opening degree, when the integral value of the opening degree within a predetermined time is larger than the threshold value, the determination unit 70 detects that the amount of refrigerant has changed.

When the determination unit 70 detects that the amount of refrigerant is changing, it stops the operation of the refrigeration cycle device 1. For example, during cooling operation, if the total amount of refrigerant decreases and the opening degrees of the heat source side first expansion valve 25 and the heat source side second expansion valve 40 are smaller than the threshold value, from the operation data accumulated in the storage unit 60, , the determination unit 70 determines that the refrigerant has leaked. When the determination unit 70 determines that the refrigerant has leaked, the determination unit 70 sends a command to the compressor 21 to stop, and stops the operation of the refrigeration cycle device 1.

The storage unit 60 and the determination unit 70 are provided in an external device. The external device is a device external to the refrigeration cycle device main body, which mainly includes the refrigerant circuit 10. Specifically, the external device is located outside the device that includes the heat source side unit 2, the usage side units 5a and 5b, the first communication pipe 6, and the second communication pipe 7. The external device in this embodiment is the local controller 9. In the local controller 9, the storage unit 60 receives the cooling operation data, and the determination unit 70 determines that the refrigerant has leaked if the amount of refrigerant has changed based on the received cooling operation data.

Note that the local controller 9 as an external device, the above-described control unit 8, the heat source side control unit 48, and the usage side control units 58a and 58b are realized by a computer. The local controller 9, the control section 8, the heat source side control section 48, and the use side control sections 58a and 58b include a control calculation device and a storage device. A processor such as a CPU or a GPU can be used as the control calculation device. The control arithmetic device reads a program stored in the storage device, and performs predetermined image processing and arithmetic processing according to this program. Furthermore, the control calculation device can write calculation results to the storage device and read information stored in the storage device according to the program. 2 and 3 show various functional blocks realized by the control calculation device. The storage device can be used as a database.

(3) Operation The refrigeration cycle device 1 executes heating operation and cooling operation using the refrigerant circuit 10.

(3-1) Cooling operation The cooling operation as the first operation will be explained using FIG. 1. In the cooling operation, the low pressure value of the refrigeration cycle (detected value of the suction pressure sensor 41) is controlled by the operating frequency of the compressor 21 so that the low pressure target value corresponds to the indoor cooling load. , 52b are adjusted so that the degree of superheat of the refrigerant at the outlet of the refrigerant reaches a predetermined target value (for example, 5° C.).

When a cooling operation instruction is given by input from a remote control (not shown) or the like, the switching mechanism 23 is activated so that the refrigerant circuit 10 enters the cooling cycle state (the state shown by the solid line of the switching mechanism 23 in FIG. 1). Switch. As a result, the compressor 21, the heat source side fan 34, and the usage side fans 55a, 55b are activated, and the heat source side first expansion valve 25, the supercooling heat exchanger side expansion valve 38, and the usage side expansion valves 51a, 51b are activated. etc. perform a predetermined operation.

Then, the low-pressure gas refrigerant in the refrigerant circuit 10 is sucked into the compressor 21 and compressed to become a high-pressure gas refrigerant. This high-pressure gas refrigerant is sent to the heat source side heat exchanger 24 through the switching mechanism 23.

The high-pressure gas refrigerant sent to the heat source side heat exchanger 24 is cooled by exchanging heat with outdoor air supplied by the heat source side fan 34 in the heat source side heat exchanger 24, which functions as a refrigerant condenser. As a result, it condenses into a high-pressure liquid refrigerant. This high-pressure liquid refrigerant is sent to the subcooling heat exchanger 39 through the heat source side first expansion valve 25 .

At this time, a part of the high-pressure liquid refrigerant flowing through the first refrigerant pipe 26 on the heat source side is branched to the bypass pipe 35 and is reduced in pressure by the expansion valve 38 on the subcooling heat exchanger side. Then, the refrigerant whose pressure has been reduced by the subcooling heat exchanger side expansion valve 38 is sent to the subcooling heat exchanger 39, where it is heated by exchanging heat with the high pressure liquid refrigerant flowing through the heat source side first refrigerant pipe 26. The refrigerant is evaporated into a gaseous refrigerant and returned to the compressor 21.

The high-pressure liquid refrigerant sent to the subcooling heat exchanger 39 exchanges heat with the refrigerant flowing through the bypass pipe 35 to be further cooled, and is depressurized by the second expansion valve 40 on the heat source side and becomes a gas-liquid two-phase refrigerant. , the first shutoff valve 32 and the first communication pipe 6, the heat is sent from the heat source side unit 2 to the use side units 5a, 5b.

The gas-liquid two-phase refrigerant sent to the usage-side units 5a, 5b is further reduced in pressure by the usage-side expansion valves 51a, 51b, and becomes a low-pressure gas-liquid two-phase refrigerant. This low-pressure gas-liquid two-phase refrigerant is sent to the utilization side heat exchangers 52a and 52b.

The low-pressure gas-liquid two-phase refrigerant sent to the usage-side heat exchangers 52a, 52b is supplied by usage-side fans 55a, 55b in the usage-side heat exchangers 52a, 52b, which function as refrigerant evaporators. It exchanges heat with indoor air and is heated, evaporating and becoming a low-pressure gas refrigerant. This low-pressure gas refrigerant is sent to the heat source unit 2 from the usage units 5a and 5b through the second communication pipe 7.

The low-pressure gas refrigerant sent to the heat source side unit 2 is sucked into the compressor 21 again through the second closing valve 33 and the switching mechanism 23.

(3-2) Heating operation The heating operation as the second operation will be explained using FIG. 1. In the heating operation, the high pressure value of the refrigeration cycle (detected value of the discharge pressure sensor 43) is controlled by the operating frequency of the compressor 21 so that the high pressure target value corresponds to the heating load, and the high pressure value of the refrigeration cycle is controlled by the operating frequency of the compressor 21. The opening degrees of the usage-side expansion valves 51a and 51b are adjusted so that the degree of subcooling of the refrigerant at the outlet of the refrigerant reaches a predetermined target value (for example, 5° C.).

When heating operation is instructed by input from a remote control (not shown) or the like, the switching mechanism 23 is activated so that the refrigerant circuit 10 enters the heating cycle state (the state shown by the broken line of the switching mechanism 23 in FIG. 1). The compressor 21, the heat source side fan 34, and the usage side fans 55a and 55b start, and the heat source side first expansion valve 25, the supercooling heat exchanger side expansion valve 38, and the usage side expansion valves 51a and 51b start. etc. perform a predetermined operation.

Then, the low-pressure gas refrigerant in the refrigerant circuit 10 is sucked into the compressor 21 and compressed to become a high-pressure gas refrigerant. This high-pressure gas refrigerant is sent from the heat source side unit 2 to the usage side units 5a and 5b through the switching mechanism 23, the second closing valve 33, and the second communication pipe 7. The high pressure gas refrigerant sent to the usage side units 5a, 5b is sent to the usage side heat exchangers 52a, 52b.

The high-pressure gas refrigerant sent to the user-side heat exchangers 52a, 52b exchanges heat with indoor air supplied by the user-side fans 55a, 55b in the user-side heat exchangers 52a, 52b, which function as refrigerant condensers. As it is cooled, it condenses and becomes a high-pressure liquid refrigerant. This high-pressure liquid refrigerant is depressurized by the usage-side expansion valves 51a, 51b to become a gas-liquid two-phase state, and is sent from the usage-side units 5a, 5b to the heat source-side unit 2 through the first communication pipe 6.

The refrigerant sent to the heat source side unit 2 is sent to the heat source side first expansion valve 25 through the first closing valve 32 and the subcooling heat exchanger 39, and is further depressurized by the heat source side first expansion valve 25 to become low pressure. It becomes a gas-liquid two-phase refrigerant. This low-pressure gas-liquid two-phase refrigerant is sent to the heat source side heat exchanger 24.

The low-pressure gas-liquid two-phase refrigerant sent to the heat source side heat exchanger 24 exchanges heat with outdoor air supplied by the heat source side fan 34 in the heat source side heat exchanger 24 which functions as a refrigerant evaporator. When heated, it evaporates and becomes a low-pressure gas refrigerant. This low-pressure gas refrigerant is sucked into the compressor 21 again through the switching mechanism 23.

(4) Refrigerant leak determination method A refrigerant leak determination method according to an embodiment of the present disclosure will be described with reference to FIGS. 1 to 4. The refrigerant leak determination method is a method of determining whether refrigerant leaks from the refrigerant circuit 10 in the refrigeration cycle device 1 during the above-mentioned cooling operation and heating operation.

(4-1) Start of operation As shown in FIG. 4, first, cooling operation or heating operation is started in the refrigeration cycle device 1.

(4-2) Accumulation of operation data During cooling operation, the opening degrees of the heat source side first expansion valve 25 and the heat source side second expansion valve 40 are accumulated in the storage section 60 as operation data. During the heating operation, the opening degrees of the user-side expansion valves 51a and 51b are accumulated in the accumulation section 60 as operation data.

(4-3) Judgment of refrigerant leakage Next, in the cooling operation, the opening degree of the heat source side first expansion valve 25 and the heat source side second expansion valve 40 is used as an index, and in the heating operation, the opening degree of the user side expansion valve 51a, 51b is Changes in the amount of refrigerant are detected using an index using the degree of opening. When the determination unit 70 detects that the amount of refrigerant is changing, it determines that the refrigerant has leaked. When it is determined that the refrigerant has leaked, the operation of the refrigeration cycle device 1 is stopped.

On the other hand, if the determination unit 70 does not determine that the refrigerant has leaked, the operation continues.

(5) Features In the refrigeration cycle device 1 of this embodiment, the refrigerant in the first communication pipe 6 is maintained in a gas-liquid two-phase state during the cooling operation as the first operation. As a result, the amount of refrigerant flowing through the first communication pipe 6 during cooling operation becomes smaller than when refrigerant in a liquid phase flows. In other words, the gas-liquid two-phase refrigerant in the first communication pipe 6 reduces the buffer effect compared to the case where liquid-phase refrigerant flows. Therefore, even if the amount of refrigerant changes is small, it will affect the cooling operation, so refrigerant amount detection processing that detects changes in the amount of refrigerant in the refrigerant circuit 10 must be performed with high accuracy. I can do it. In other words, if even a small amount of refrigerant leaks, the refrigerant shortage will affect the operation, so the sensitivity for detecting refrigerant leakage will be increased, so the accuracy for detecting refrigerant leakage can be improved. Furthermore, in the present embodiment, refrigerant leakage can be detected with high accuracy based on changes in the amount of refrigerant when normal cooling operation is performed without performing leakage detection operation. Similarly, even during the heating operation as the second operation, by keeping the refrigerant in the first communication pipe 6 in a gas-liquid two-phase state, refrigerant leakage can be detected with high accuracy.

In particular, in order to easily maintain the refrigerant in the first communication pipe 6 in a gas-liquid two-phase state, a heat source side second expansion valve 40 may be provided on the outlet side of the subcooling heat exchanger 39 in the first operation. preferable. Then, while measuring the change in the opening degree of the heat source side second expansion valve 40, the change in the total amount of refrigerant is measured, and when the amount of refrigerant decreases and the opening degree of the heat source side second expansion valve 40 is larger than the threshold value, By determining that the refrigerant has leaked, the accuracy of detecting the refrigerant leak can be further improved.

In addition, in order to detect refrigerant leakage with higher accuracy, during the first operation, at least the degree of pressure reduction of the heat source side expansion mechanism is adjusted to bring all the refrigerant in the first connecting pipe into a gas-liquid two-phase state. It is preferable to keep it. During the cooling operation, which is the first operation, all the refrigerant flowing from the heat source side second expansion valve 40 disposed on the outlet side of the subcooling heat exchanger 39 toward each user side expansion valve 51a, 51b is transferred into two gas-liquid phase. It is more preferable to maintain the condition. Similarly, in order to detect refrigerant leakage with higher accuracy, during the second operation, at least the degree of depressurization of the user-side expansion mechanism is adjusted to bring all the refrigerant in the first connecting pipe into a gas-liquid two-phase state. It is preferable to keep it at

(6) Modification (6-1) Modification A
In the embodiment described above, the heat source side expansion mechanism including the heat source side first expansion valve 25 and the heat source side second expansion valve 40 has been described as an example, but the present invention is not limited thereto. In this modification, the heat source side second expansion valve 40 is omitted. For this reason, during cooling operation, at least the degree of pressure reduction of the heat source side first expansion valve 25 is adjusted to maintain the refrigerant in the first communication pipe 6 in a gas-liquid two-phase state.

(6-2) Modification B
In the embodiment described above, the storage section 60 and the determination section 70 are provided in the local controller 9 as external devices, but the present invention is not limited thereto. The storage unit 60 and the determination unit 70 may be provided in a cloud server. In this case, the storage section 60 and the determination section 70 may be directly connected to the heat source side unit 2, or may be connected to the heat source side unit 2 via a local controller.

Further, the storage section 60 and the determination section 70 may be provided within the heat source side unit 2 instead of being provided in the external device.

(6-3) Modification C
In the embodiment described above, the storage unit 60 accumulates data regarding the opening degree of at least one of the heat source side first expansion valve 25 and the heat source side second expansion valve 40, and the determination unit 70 stores data regarding the opening degree of at least one of the heat source side first expansion valve 25 and the heat source side second expansion valve 40. Although it is determined whether or not the refrigerant has leaked based on a change in the opening degree of at least one of the second expansion valves 40 on the heat source side, the present invention is not limited thereto. In this modification, the storage unit 60 stores the outlet temperature Tb of the heat source side heat exchanger 24 measured by the heat source side heat exchanger outlet temperature sensor 45, which is a condenser outlet temperature sensor. The storage unit 60 also stores the discharge pressure Hp of the discharge pressure sensor 43. The determination unit 70 determines the degree of supercooling (subcool SC=Tc−Tb) or the degree of supercooling corrected by the outside air temperature Ta from the condensing temperature Tc calculated from the discharge pressure Hp of the discharge pressure sensor 43 and the condenser outlet temperature Tb. The corresponding value ((Tc-Tb)/(Tc-Ta)) is calculated. Further, the determination unit 70 predicts the degree of supercooling or a reference value of a value corresponding to the degree of supercooling. When the difference between the calculated degree of subcooling or the value corresponding to the degree of subcooling and the predicted reference value exceeds a predetermined value, the determination unit 70 determines that the refrigerant has leaked. On the other hand, the determination unit 70 determines that the refrigerant is not leaking if the difference between the calculated degree of subcooling or the value corresponding to the degree of subcooling and the reference value is less than or equal to a predetermined value.

Note that the determining unit 70 may determine that the refrigerant has leaked based on an index using the degree of superheat (SH: super heat), the degree of discharge superheat (DSH: discharge super heat), and values corresponding thereto.

Although the embodiments of the present disclosure have been described above, it will be understood that various changes in form and details can be made without departing from the spirit and scope of the present disclosure as described in the claims. .

1: Refrigeration cycle device 2: Heat source side units 5a, 5b: User side unit 6: First connecting pipe 7: Second connecting pipe 8: Control part 8a: Transmission line 9: Local controller 10: Refrigerant circuit 15: Controller 21: Compressor 22: Compressor motor 23: Switching mechanism 24: Heat source side heat exchanger 25: Heat source side first expansion valve 26: Heat source side first refrigerant pipe 27: Suction pipe 28: Accumulator 29: Discharge pipe 30: Heat source side Second refrigerant pipe 31 : Heat source side third refrigerant pipe 32 : First closing valve 33 : Second closing valve 34 : Heat source side fan 35 : Bypass pipe 36 : Refrigerant return inlet pipe 37 : Refrigerant return outlet pipe 38 : Supercooling heat Exchanger side expansion valve 39 : Supercooling heat exchanger 40 : Heat source side second expansion valve 41 : Suction pressure sensor 42 : Suction temperature sensor 43 : Discharge pressure sensor 44 : Discharge temperature sensor 45 : Heat source side heat exchanger outlet temperature sensor 46: Subcooling heat exchanger outlet temperature sensor 47: Data transmitting unit 48: Heat source side control unit 51a, 51b: Usage side expansion valve 52a, 52b: Usage side heat exchanger 53a, 53b: Usage side first refrigerant pipe 54a, 54b: User-side second refrigerant pipes 55a, 55b: User-side fans 56a, 56b: User-side heat exchanger inlet temperature sensors 57a, 57b: User-side heat exchanger outlet temperature sensors 58a, 58b: User-side control unit 60: Accumulation Section 70: Judgment section

International Publication No. 2018/062485

Claims (5)

A refrigeration cycle device that detects a change in the amount of refrigerant in a refrigerant circuit (10),
a heat source side unit (2) including a compressor (21), a heat source side heat exchanger (24), and a heat source side expansion mechanism (25, 40);
A user-side unit (5a, 5b) including a plurality of user-side heat exchangers (52a, 52b) and a plurality of user-side expansion mechanisms (51a, 51b);
a first connection pipe (6) connecting the heat source side unit and the usage side unit;
During a first operation in which the heat source side unit and the usage side unit are connected and the usage side heat exchanger functions as an evaporator, a refrigerant having a pressure lower than that of the refrigerant in the first communication pipe passes through a first operation. 2 connection piping (7),
Equipped with
During the first operation, at least the degree of pressure reduction of the heat source side expansion mechanism is adjusted to maintain the refrigerant in the first communication pipe in a gas-liquid two-phase state;
The heat source side expansion mechanism has a heat source side expansion valve (25, 40) whose opening degree can be changed,
A refrigeration cycle device (1) that detects a change in the amount of refrigerant based on an index using the opening degree of the heat source side expansion valve . The heat source side expansion mechanism has a heat source side expansion valve (25, 40) whose opening degree can be changed,
The refrigeration cycle device according to claim 1, wherein the degree of pressure reduction of the heat source side expansion mechanism is adjusted by adjusting the opening degree of the heat source side expansion valve. The refrigeration cycle device according to claim 1 or 2 , further comprising a determination unit (70) that determines that the refrigerant has leaked when detecting that the amount of refrigerant has changed. The refrigeration cycle apparatus according to any one of claims 1 to 3 , further comprising an accumulation section (60) that accumulates data of the first operation. A refrigeration cycle device that detects a change in the amount of refrigerant in a refrigerant circuit (10),
a heat source side unit (2) including a compressor (21), a heat source side heat exchanger (24), and a heat source side expansion mechanism (25, 40);
A user-side unit (5a, 5b) including a plurality of user-side heat exchangers (52a, 52b) and a plurality of user-side expansion mechanisms (51a, 51b);
a first connection pipe (6) connecting the heat source side unit and the usage side unit;
During a second operation in which the heat source side unit and the usage side unit are connected and the usage side heat exchanger functions as a condenser, a refrigerant having a higher pressure than the refrigerant in the first communication pipe passes through a second operation. 2 connection piping (7),
Equipped with
During the second operation, at least the degree of pressure reduction of the user-side expansion mechanism is adjusted to maintain the refrigerant in the first communication pipe in a gas-liquid two-phase state;
The user-side expansion mechanism has a user-side expansion valve (51a, 51b) whose opening degree can be changed,
A refrigeration cycle device (1) that detects a change in the amount of refrigerant based on an index using the opening degree of the usage-side expansion valve .

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