Heat pump device

Abstract

To provide a heat pump system that can operate continuously while suppressing the risk of ignition. [Solution] The heat pump system performs air conditioning operation in the space to be air-conditioned. The heat pump system comprises a utilization unit, a heat source unit, a sub-unit, a refrigerant circuit, and a control unit. The utilization unit has a utilization heat exchanger. The heat source unit has a heat source heat exchanger and a compressor. The sub-unit has an expansion mechanism that reduces the pressure of the flammable refrigerant flowing between the utilization unit and the heat source unit. The refrigerant circuit is configured by connecting the utilization unit and the sub-unit with a first connecting pipe, and connecting the sub-unit and the heat source unit with a second connecting pipe. The control unit controls the expansion mechanism based on volume information regarding the volume of the first connecting pipe and refrigerant information regarding the temperature and pressure of the refrigerant flowing through the refrigerant circuit, and performs a first control to reduce the amount of refrigerant flowing through the utilization unit and the first connecting pipe to a predetermined amount or less.

Description

Technical Field

[0001] It relates to a heat pump device.

Background Art

[0002] In recent years, due to the increasing concern for the global environment, refrigerants with a low Global Warming Potential that do not significantly affect the destruction of the ozone layer and global warming have attracted attention. Such refrigerants may be flammable. Therefore, a heat pump device using such a refrigerant is required to ensure safety so that it does not catch fire even when the refrigerant leaks. For example, Patent Document 1 (Japanese Unexamined Patent Application Publication No. 2016-166680) proposes performing control to drive an indoor fan to stir the refrigerant and reduce the concentration of the refrigerant when the refrigerant leaks in an indoor unit using a flammable refrigerant.

[0003] In addition, there are regulations to limit the amount of refrigerant filled in the refrigerant circuit in order to prevent the leaked refrigerant from reaching a high concentration outside the refrigerant circuit.

Summary of the Invention

Problems to be Solved by the Invention

[0004] If the amount of refrigerant filled in the refrigerant circuit is reduced, the amount of heat that can be transported will also decrease. Therefore, when an air conditioning system is constructed with that amount of refrigerant, the air conditioning capacity will be limited.

[0005] An object of the present disclosure is to provide a heat pump device capable of reducing the risk during refrigerant leakage while ensuring the amount of refrigerant that can be filled.

Means for Solving the Problems

[0006] The heat pump system in the first aspect performs air conditioning operation for a space to be air-conditioned. The heat pump system comprises a utilization unit, a heat source unit, a sub-unit, a refrigerant circuit, and a control unit. The utilization unit has a utilization heat exchanger. The heat source unit has a heat source heat exchanger and a compressor. The sub-unit has an expansion mechanism that reduces the pressure of the flammable refrigerant flowing between the utilization unit and the heat source unit. The refrigerant circuit is configured by connecting the utilization unit and the sub-unit with a first connecting pipe, and connecting the sub-unit and the heat source unit with a second connecting pipe.

[0007] The control unit controls the expansion mechanism based on volume information regarding the volume of the first connecting pipe and refrigerant information regarding the temperature and pressure of the refrigerant flowing through the refrigerant circuit, and performs a first control to reduce the amount of refrigerant flowing through the utilization unit and the first connecting pipe to a predetermined amount or less.

[0008] This heat pump system makes it possible to control the amount of refrigerant flowing through the utilization unit and the first connecting pipe to a predetermined amount or less, regardless of the total amount of refrigerant filled into the refrigerant circuit. Therefore, even if refrigerant leaks from the utilization unit, the amount of leakage can be kept within a certain range, and the risk of ignition in the event of a refrigerant leak can be suppressed. Thus, this heat pump system makes it possible to reduce the risk in the event of a refrigerant leak while ensuring a sufficient amount of refrigerant can be filled.

[0009] The heat pump device of the second aspect is the heat pump device of the first aspect, wherein the subunit further includes a liquid pipe and a gas pipe, one end of which is connected to a first connecting pipe and the other end to a second connecting pipe, and a shut-off mechanism for blocking the passage of refrigerant flowing through the gas pipe.

[0010] This heat pump system can suppress further refrigerant leakage by closing the shut-off mechanism when refrigerant leakage occurs from the user unit, thereby preventing the circulation of refrigerant from the heat source unit to the user unit.

[0011] The heat pump device in the third perspective is the heat pump device in the second perspective, and the refrigerant information includes first refrigerant information and second refrigerant information. The first refrigerant information is the temperature and pressure of the refrigerant flowing between the end of the first connecting pipe connected to the utilization unit and the liquid side end of the heat source heat exchanger. The second refrigerant information is the temperature and pressure of the refrigerant flowing between the end of the first connecting pipe connected to the utilization unit and the compressor. In the first control, the control unit controls the expansion mechanism based on the average density of the refrigerant in the utilization unit and the first connecting pipe calculated using the first refrigerant information and the second refrigerant information.

[0012] This heat pump system can control the expansion mechanism based on the average density obtained using first and second refrigerant information.

[0013] The heat pump device of the fourth perspective is the heat pump device of the third perspective, wherein the subunit further comprises a first detection unit and a second detection unit. The first detection unit detects first refrigerant information R1 between the end of the liquid piping on the first connecting pipe side and the expansion mechanism. The second detection unit detects second refrigerant information R2 between the end of the gas piping on the first connecting pipe side and the shut-off mechanism.

[0014] The heat pump device of the fifth perspective is any of the heat pump devices of the first, fourth, or fourth perspectives, and the volume information includes first volume information relating to the length of the first connecting pipe and second volume information relating to the identification of the utilization unit.

[0015] This heat pump device can control the expansion mechanism based on first volume information and second volume information.

[0016] The heat pump device in the sixth aspect is the heat pump device in the fifth aspect, and the second volume information includes the model name of the unit being used or the internal volume of the unit being used.

[0017] The heat pump device of the seventh aspect is the heat pump device of the third aspect, and in the first control, the control unit controls the expansion mechanism so as to satisfy the following equation, where Da is the average density of the refrigerant and v is the internal volume of the utilization unit and the first connecting pipe. TIFF0007879476000001.tif9170

[0018] This heat pump system can control the expansion mechanism based on the average density of the refrigerant, Da, and the internal volume v of the utilization unit and the first connecting pipe.

[0019] The heat pump device of the eighth perspective is the heat pump device of the third perspective, further performing a pump-down operation in which the refrigerant in the portion of the refrigerant circuit included in the utilization unit is recovered into the portion of the refrigerant circuit included in the heat source unit.

[0020] In this heat pump system, the amount of refrigerant flowing through the utilization unit and the first connecting pipe is controlled by the first control to be below a predetermined amount, so that the recovery of refrigerant into the part included in the heat source unit can be completed quickly.

[0021] The heat pump device of the ninth perspective is any of the heat pump devices of the first to eighth perspectives, further comprising an input unit for receiving volume information. The control unit does not start air conditioning operation if no volume information is received.

[0022] This heat pump system can suppress refrigerant leakage by not starting air conditioning operation when volume information necessary for controlling the expansion mechanism is not input.

[0023] The heat pump device of the tenth perspective is the heat pump device of the third perspective, further comprising a refrigerant sensor for detecting the refrigerant in the space to be air-conditioned. The control unit controls the shut-off mechanism based on the detection result of the refrigerant sensor.

[0024] When refrigerant leakage occurs from the utilization unit, this heat pump device suppresses the circulation of refrigerant from the heat source unit to the utilization unit by closing the shut-off mechanism, thereby suppressing further refrigerant leakage.

[0025] The heat pump device according to the 11th aspect is any one of the heat pump devices according to the 1st to 10th aspects, and the expansion mechanism can be fully closed.

[0026] Since this heat pump device can suppress refrigerant leakage with the expansion mechanism, the shut-off mechanism is unnecessary. Therefore, the manufacturing cost of this heat pump device is suppressed.

Brief Description of the Drawings

[0027] [Figure 1] It is a schematic diagram of the heat pump device 1. [Figure 2] It is a schematic diagram showing the connection relationship between the control unit 80 and each part. [Figure 3] It is a flowchart showing the control flow of the first control. [Figure 4] Schematic diagram of the heat pump device 1 according to Modification 3 [Figure 5] It is a schematic diagram of the heat pump device 1a. [Figure 6] It is a schematic diagram showing the connection relationship between the control unit 80a and each part. [Figure 7] It is a schematic diagram of the heat pump device 1b. [Figure 8] It is a schematic diagram showing the connection relationship between the control unit 80b and each part.

Modes for Carrying Out the Invention

[0028] <First Embodiment> (1) Overall Configuration FIG. 1 is a schematic diagram of a heat pump device 1 according to a first embodiment of the present disclosure. The heat pump device 1 is a refrigeration cycle device that performs heating operation and cooling operation, which are air conditioning operations for an air conditioning target space Ro such as a building interior, by executing a vapor compression refrigeration cycle.

[0029] The heat pump device 1 includes a utilization unit 10, a heat source unit 20, a subunit 30, a first connecting pipe 40, a second connecting pipe 50, an input unit 60, and a control unit 80.

[0030] The refrigerant circuit 100 is formed by connecting the utilization unit 10 and the subunit 30 with a first connecting pipe 40, and connecting the subunit 30 and the heat source unit with a second connecting pipe 50. The refrigerant circuit 100 is filled with refrigerant. The refrigerant filled in the refrigerant circuit 100 is flammable R290 (propane). A flammable refrigerant refers to a refrigerant classified as 2L or more in the US ANSI / ASHRAE 34 standard.

[0031] As will be described in more detail later, the heat pump device 1 performs a first control to keep the amount of refrigerant flowing through the utilization unit 10 and the first connecting pipe 40 below a predetermined amount, and a second control to suppress further refrigerant leakage if refrigerant leakage occurs from the equipment constituting the utilization unit 10.

[0032] (2) Detailed configuration (2-1) Usage Unit 10 The utilization unit 10 includes a utilization heat exchanger 11.

[0033] (2-2-1) Utilized heat exchanger 11 The heat exchanger 11 causes the heat transfer medium circulating in the refrigerant circuit 100 to exchange heat with the air in the air-conditioned space Ro. The heat exchanger 11 has a liquid side end 11b and a gas side end 11a. The gas side end 11a and the liquid side end 11b are connected to the first connecting pipe 40. Specifically, the gas side end 11a is connected to the first gas connecting pipe 40b (described later). The liquid side end 11b is connected to the first liquid connecting pipe 40a (described later). (2-2) Heat source unit 20 The heat source unit 20 includes a compressor 21, a heat source heat exchanger 22, a four-way switching valve 23, a receiver tank 24, an accumulator 25, and a first expansion valve 26.

[0034] (2-2-2) Compressor 21 The compressor 21 compresses the low-pressure refrigerant in the refrigerant circuit 100 and then discharges it as high-pressure refrigerant in the refrigerant circuit 100. The compressor 21 has an intake section 21a and a discharge section 21b. The compressor 21 is controlled by the control unit 80.

[0035] The compressor 21 compresses the low-pressure refrigerant drawn in from the suction port 21a and discharges it as high-pressure refrigerant from the discharge port 21b.

[0036] (2-2-3) Heat source heat exchanger 22 The heat source heat exchanger 22 causes the refrigerant circulating in the refrigerant circuit 100 to exchange heat with a heat source (for example, outdoor air). The heat source heat exchanger 22 has a gas-side end 22a and a liquid-side end 22b.

[0037] (2-2-4) Four-way switching valve 23 The four-way switching valve 23 has a first port 23a, a second port 23b, a third port 23c, and a fourth port 23d. Based on instructions from the control unit 80, the four-way switching valve 23 switches between a first state and a second state in which the communication status of the first port 23a, second port 23b, third port 23c, and fourth port 23d is different. In the first state, the first port 23a and the second port 23b are in communication, and the third port 23c and the fourth port 23d are in communication. In the second state, the first port 23a and the fourth port 23d are in communication, and the second port 23b and the third port 23c are in communication.

[0038] The first port 23a is connected to the discharge section 21b of the compressor 21. The second port 23b is connected to the end 50ba of the second gas connecting pipe 50b (described later) on the heat source unit 20 side. The third port 23c is connected to the accumulator 25. The fourth port 23d is connected to the gas side end 22a of the heat source heat exchanger 22.

[0039] (2-2-5) Receiver Tank 24 The receiver tank 24 is a tank for storing excess refrigerant and circulating an appropriate amount of refrigerant within the refrigerant circuit 100. The receiver tank 24 has a first communication passage 24a and a second communication passage 24b. The first communication passage 24a and the second communication passage 24b communicate with the inside of the receiver tank 24.

[0040] The first connecting passage 24a is connected to the liquid-side end 22b of the heat source heat exchanger 22. The second connecting passage 24b is connected to the end 50aa of the second liquid connecting pipe 50a (described later) on the heat source unit 20 side.

[0041] (2-2-6) Accumulator 25 The accumulator 25 is a container for storing excess refrigerant and circulates an appropriate amount of refrigerant within the refrigerant circuit 100. The accumulator 25 has a first communication passage 25a and a second communication passage 25b. The first communication passage 25a and the second communication passage 25b communicate with the inside of the accumulator 25.

[0042] The first communication passage 25a is connected to the third port 23c of the four-way switching valve 23. The second communication passage 25b is connected to the suction section 21a of the compressor 21.

[0043] (2-2-7) First expansion valve 26 The first expansion valve 26 adjusts and reduces the flow rate of the refrigerant passing through it by changing its opening degree based on instructions from the control unit 80.

[0044] The first expansion valve 26 is provided in the refrigerant piping that connects the first communication passage 24a of the receiver tank 24 to the liquid side end 22b of the heat source heat exchanger 22.

[0045] (2-3) Subunit 30 The subunit 30 includes a liquid pipe 31, a gas pipe 32, a second expansion valve 33, a liquid-side shut-off valve 34a, a gas-side shut-off valve 34b, a first detection unit 35, and a second detection unit 36.

[0046] (2-3-1) Liquid piping 31 and gas piping 32 The liquid piping 31 and the gas piping 32 are refrigerant pipes, with a first connecting pipe 40 connected to one end and a second connecting pipe 50 connected to the other end.

[0047] More specifically, liquid piping 31 is a refrigerant pipe with a first liquid connecting pipe 40a (described later) connected to one end and a second liquid connecting pipe 50a (described later) connected to the other end. Gas piping 32 is a refrigerant pipe with a first gas connecting pipe 40b (described later) connected to one end and a second gas connecting pipe 50b (described later) connected to the other end.

[0048] (2-3-2) Second expansion valve 33 The second expansion valve 33 adjusts the flow rate of the refrigerant passing through it and reduces the pressure by changing its opening degree based on instructions from the control unit 80. The second expansion valve 33 is an example of an expansion mechanism.

[0049] The second expansion valve 33 is installed in the liquid piping 31 and reduces the pressure of the refrigerant flowing between the utilization unit 10 and the heat source unit 20.

[0050] (2-3-3) Liquid-side shut-off valve 34a and gas-side shut-off valve 34b The liquid-side shut-off valve 34a and the gas-side shut-off valve 34b switch between an open state and a closed state based on instructions from the control unit 80. The gas-side shut-off valve 34b is an example of a shut-off mechanism.

[0051] The liquid-side shut-off valve 34a is installed in the liquid piping 31 between the second expansion valve 33 and the second liquid connecting pipe 50a. This allows the liquid-side shut-off valve 34a to block the passage of refrigerant flowing through the liquid piping 31.

[0052] The gas-side shut-off valve 34b is installed in the gas piping 32. This allows the gas-side shut-off valve 34b to block the passage of refrigerant flowing through the gas piping 32.

[0053] (2-3-4) First detection unit 35 and second detection unit 36 The first detection unit 35 detects the first refrigerant information R1 used in the first control. The first refrigerant information R1 is the temperature t1 and pressure p1 of the refrigerant flowing between the end 40aa of the first liquid connecting pipe 40a (described later), which is connected to the liquid pipe 31, and the liquid side end 22b of the heat source heat exchanger 22.

[0054] The first detection unit 35 includes a pressure sensor 35a for detecting pressure p1 during heating and cooling operations, a temperature sensor 35b for detecting temperature t1 during heating operations, and a temperature sensor 35c for detecting temperature t1 during cooling operations.

[0055] In this embodiment, the pressure sensor 35a detects the refrigerant pressure between the end of the liquid piping 31 on the first liquid connecting pipe 40a side and the second expansion valve 33. The temperature sensor 35b detects the refrigerant temperature between the end of the liquid piping 31 on the first liquid connecting pipe 40a side and the second expansion valve 33. The temperature sensor 35c detects the refrigerant temperature inside the liquid piping 31 between the second expansion valve 33 and the liquid side shut-off valve 34a.

[0056] The second detection unit 36 ​​detects the second refrigerant information R2 used in the first control. The second refrigerant information R2 is the temperature t2 and pressure p2 of the refrigerant flowing between the end 40ba of the first gas communication pipe 40b (described later), which is connected to the gas pipe 32, and the utilization unit 10, and the compressor 21.

[0057] The second detection unit 36 ​​includes a pressure sensor 36a that detects the pressure p2 during heating and cooling operations, and a temperature sensor 36b that detects the temperature t2 during heating and cooling operations.

[0058] In this embodiment, the pressure sensor 36a detects the refrigerant pressure between the end of the gas piping 32 on the first gas connecting pipe 40b side and the gas-side shut-off valve 34b. The temperature sensor 36b detects the refrigerant temperature between the end of the gas piping 32 on the first gas connecting pipe 40b side and the gas-side shut-off valve 34b.

[0059] (2-4) First connecting pipe 40 The first connecting pipe 40 is a pipe that connects the user unit 10 and the subunit 30. The first connecting pipe 40 includes the first liquid connecting pipe 40a and the first gas connecting pipe 40b.

[0060] The first liquid connecting pipe 40a connects the liquid-side end 11b of the heat exchanger 11 to the liquid piping 31 of the subunit 30. The first liquid connecting pipe 40a has an end 40aa connected to the liquid-side end 11b of the heat exchanger 11 and an end 40ab connected to the liquid piping 31 of the subunit 30.

[0061] The first gas connecting pipe 40b connects the gas-side end 11a of the heat exchanger 11 to the gas piping 32 of the subunit 30. The first gas connecting pipe 40b has an end 40ba connected to the gas-side end 11a of the heat exchanger 11 and an end 40bb connected to the gas piping 32 of the subunit 30.

[0062] (2-5) Second connecting pipe 50 The second connecting pipe 50 is a pipe that connects the heat source unit 20 and the subunit 30. The second connecting pipe 50 includes a second liquid connecting pipe 50a and a second gas connecting pipe 50b.

[0063] The second liquid communication pipe 50a connects the second communication passage 24b of the receiver tank 24 to the liquid piping 31 of the subunit 30. The second liquid communication pipe 50a has an end 50aa connected to the second communication passage 24b and an end 50ab connected to the liquid piping 31 of the subunit 30.

[0064] The second gas connecting pipe 50b connects the second port 23b of the four-way switching valve 23 to the gas piping 32 of the subunit 30. The second gas connecting pipe 50b has an end 50ba connected to the second port 23b of the four-way switching valve 23 and an end 50bb connected to the gas piping 32 of the subunit 30.

[0065] (2-6) Input section 60 The input unit 60 is a terminal that receives various information used for the operation of the heat pump device 1. The control unit 80 acquires the information received by the input unit 60. The input unit 60 receives volume information V and the set temperature for air conditioning operation. The input unit 60 is typically a remote control.

[0066] Volume information V includes first volume information V1 relating to the length of the first connecting pipe 40 and second volume information V2 relating to the identification of the utilization unit 10. Second volume information V2 includes the model name of the utilization unit 10 or the internal volume of the utilization unit 10.

[0067] (2-7) Refrigerant sensor 70 The refrigerant sensor 70 detects the concentration of refrigerant in the air-conditioned space Ro. The control unit 80 acquires the detection result from the refrigerant sensor 70.

[0068] (2-8) Control unit 80 The control unit 80 controls the operation of each component of the heat pump system 1 to realize heating and cooling operation and the first control.

[0069] The control unit 80 is electrically connected to the compressor 21, the four-way switching valve 23, the first expansion valve 26, the second expansion valve 33, the liquid-side shut-off valve 34a, the gas-side shut-off valve 34b, the first detection unit 35, the second detection unit 36, the input unit 60, and the refrigerant sensor 70 so as to be able to send and receive control signals and the like. Figure 2 is a schematic diagram showing the connection relationship between the control unit 80 and each of the parts.

[0070] The control unit 80 is implemented by a computer. The control unit 80 comprises a control arithmetic unit and a storage device 81. The control arithmetic unit is a processor such as a CPU or GPU. The control arithmetic unit reads a program stored in the storage device 81 and performs predetermined image processing and calculation processing according to this program. Furthermore, the control arithmetic unit writes the calculation results to the storage device 81 and reads information stored in the storage device 81 according to the program.

[0071] The storage device 81 stores the initial values ​​of the set temperature and volume information V. The control unit 80 overwrites the initial values ​​of the set temperature and volume information V stored in the storage device 81 with the set temperature and volume information V received by the input unit 60.

[0072] The storage device 81 stores information regarding the internal volume of the user unit 10, which is linked to the second volume information V2 related to the identification of the user unit 10.

[0073] The storage device 81 stores information regarding the inner diameters of the first connecting pipe 40 and the second connecting pipe 50.

[0074] (3) Overall operation (3-1) Heating operation During heating operation, the control unit 80 drives the compressor 21. Specifically, the control unit 80 controls the capacity of the compressor 21 based on the target condensation temperature calculated based on the set temperature. The control unit 80 also controls the four-way switching valve 23 to the first state and controls the liquid-side shut-off valve 34a and the gas-side shut-off valve 34b to the open state. Furthermore, the control unit 80 controls the opening degree of the first expansion valve 26 so that the degree of subcooling in the refrigerant circuit 100 becomes the target degree of subcooling pre-recorded in the control unit 80's storage device 81. The degree of subcooling is calculated based on the temperature difference obtained by converting the refrigerant pressure detected at the discharge section 21b of the compressor 21 to the refrigerant saturation temperature and subtracting the refrigerant temperature detected at the liquid-side end 11b of the heat exchanger 11 from this saturation temperature.

[0075] When the control unit 80 detects a refrigerant concentration above a predetermined level during heating operation, it executes a second control to close the liquid-side shut-off valve 34a and the gas-side shut-off valve 34b. Details of the second control will be described later.

[0076] The compressor 21 draws in the low-pressure gas phase refrigerant from the refrigerant circuit 100 through the suction port 21a and discharges it as high-pressure gas phase refrigerant through the discharge port 21b. The high-pressure gas phase refrigerant passes through the first port 23a and the second port 23b of the four-way switching valve 23 in that order, and then flows into the gas piping 32 of the subunit 30 through the second gas connecting pipe 50b.

[0077] The refrigerant flowing into the gas piping 32 passes through the open gas-side shut-off valve 34b and then flows into the first gas connecting pipe 40b. The refrigerant flowing out of the first gas connecting pipe 40b flows into the utilization heat exchanger 11 from the gas-side end 11a. The high-pressure gaseous refrigerant flowing into the utilization heat exchanger 11 condenses into high-pressure liquid refrigerant by releasing heat into the air of the air-conditioned space Ro. The refrigerant flowing out from the liquid-side end 11b of the utilization heat exchanger 11 flows into the liquid piping 31 of the subunit 30 through the first liquid connecting pipe 40a. The refrigerant flowing into the liquid piping 31 passes through the second expansion valve 33, whose opening degree is controlled, and the open liquid-side shut-off valve 34a in that order, and then flows into the second liquid connecting pipe 50a. The refrigerant flowing out of the second liquid connecting pipe 50a flows into the receiver tank 24 from the second connecting passage 24b.

[0078] The refrigerant flowing into the receiver tank 24 flows out through the first communication passage 24a, then through the first expansion valve 26 and into the heat source heat exchanger 22 from the liquid side end 22b. The first expansion valve 26, set to an appropriate opening, reduces the pressure of the high-pressure liquid phase refrigerant to a low-pressure gas-liquid two-phase refrigerant. The low-pressure gas-liquid two-phase refrigerant flowing into the heat source heat exchanger 22 evaporates by absorbing heat from the heat source and becomes a low-pressure gas phase refrigerant. The low-pressure gas phase refrigerant flowing out from the gas side end 22a of the heat source heat exchanger 22 passes through the fourth port 23d and the third port 23c of the four-way switching valve 23 in that order, and then flows into the accumulator 25 from the first communication passage 25a. The refrigerant flowing into the accumulator 25 flows out through the second communication passage 25b and then is drawn back into the compressor 21 from the suction section 21a.

[0079] (3-2) Cooling operation During cooling operation, the control unit 80 drives the compressor 21. Specifically, the control unit 80 controls the capacity of the compressor 21 based on the target evaporation temperature calculated based on the set temperature. The control unit 80 also controls the four-way switching valve 23 to the second state and controls the liquid-side shut-off valve 34a and the gas-side shut-off valve 34b to the open state. Furthermore, the control unit 80 controls the opening degree of the second expansion valve 33 so that the superheating degree in the refrigerant circuit 100 becomes the target superheating degree pre-recorded in the control unit 80's storage device 81. The superheating degree is calculated based on the temperature difference obtained by converting the refrigerant pressure detected at the suction section 21a of the compressor 21 to the refrigerant saturation temperature and subtracting the refrigerant temperature detected at the suction section 21a from this saturation temperature.

[0080] When the control unit 80 detects a refrigerant concentration above a predetermined level during cooling operation, it executes a second control to close the liquid-side shut-off valve 34a and the gas-side shut-off valve 34b. Details of the second control will be described later.

[0081] The compressor 21 draws in the low-pressure gas phase refrigerant from the refrigerant circuit 100 through the suction port 21a and discharges it as high-pressure gas phase refrigerant through the discharge port 21b. The high-pressure gas phase refrigerant passes through the first port 23a and the third port 23c of the four-way switching valve 23 in that order, and then flows into the heat source heat exchanger 22 from the gas side end 22a. The high-pressure gas phase refrigerant that flows into the heat source heat exchanger 22 condenses by releasing heat to the heat source and becomes high-pressure liquid phase refrigerant. The high-pressure liquid phase refrigerant that flows out from the liquid side end 22b of the heat source heat exchanger 22 passes through the first expansion valve 26 and then flows into the receiver tank 24 from the first connecting passage 24a. The refrigerant that flows into the receiver tank 24 flows out from the second connecting passage 24b and then flows into the second liquid connecting pipe 50a.

[0082] The refrigerant flowing into the second liquid connecting pipe 50a flows into the liquid pipe 31 of the subunit 30. The refrigerant flowing into the liquid pipe 31 passes through the open liquid-side shut-off valve 34a and the second expansion valve 33, whose opening degree is controlled, in that order, before flowing into the first liquid connecting pipe 40a. The second expansion valve 33, set to an appropriate opening degree, reduces the pressure of the high-pressure liquid phase refrigerant to a low-pressure gas-liquid two-phase refrigerant. The refrigerant flowing out from the first liquid connecting pipe 40a flows into the utilization heat exchanger 11 from the liquid-side end 11b. The low-pressure gas-liquid two-phase refrigerant flowing into the utilization heat exchanger 11 evaporates by absorbing heat from the air in the air-conditioned space Ro, becoming a low-pressure gas-phase refrigerant. The refrigerant flowing out from the gas-side end 11a of the utilization heat exchanger 11 flows into the gas pipe 32 of the subunit 30 through the first gas connecting pipe 40b. The refrigerant that flows into the gas piping 32 passes through the open gas-side shut-off valve 34b and then flows into the second gas connecting piping 50b.

[0083] The refrigerant that flows out from the second gas communication pipe 50b flows into the four-way switching valve 23, passes through the second port 23b and the third port 23c in that order, and then flows into the accumulator 25 from the first communication passage 25a. The refrigerant that flows into the accumulator 25 flows out from the second communication passage 25b and is then drawn back into the compressor 21 from the suction section 21a.

[0084] (3-3) First control (3-3-1) Overview of Control In the first control, the control unit 80 sets the amount of refrigerant flowing through the utilization unit 10 and the first connecting pipe 40 to a predetermined amount or less.

[0085] In the first control, the control unit 80 controls the second expansion valve 33 based on volume information V relating to the internal volume of the first connecting pipe 40 and refrigerant information R relating to the temperature and pressure of the refrigerant flowing through the refrigerant circuit, thereby keeping the amount of refrigerant flowing through the utilization unit 10 and the first connecting pipe 40 below a predetermined amount. The refrigerant information R includes the first refrigerant information R1 and the second refrigerant information R2 described above.

[0086] In the first control, the control unit 80 calculates the average refrigerant density Da (kg / m³) in the utilization unit 10 and the first connecting pipe 40 using the first refrigerant information R1 and the second refrigerant information R2.3 The second expansion valve 33 is controlled based on the following.

[0087] In the first control, the control unit 80 determines the internal volume of the utilization unit 10 and the first connecting pipe 40 as internal volume v(m). 3 ) and assuming that the weight threshold of the refrigerant in the utilization unit 10 and the first connecting pipe 40 is the threshold weight w (kg), the second expansion valve 33 is controlled to satisfy the following (Equation 1).

[0088] TIFF0007879476000002.tif11170

[0089] (3-3-2) Control Flow Figure 3 is a flowchart showing the control flow of the first control. When heating or cooling operation starts, the control unit 80 starts the first control and proceeds to step S100.

[0090] In step S100, the control unit 80 acquires volume information V and proceeds to step S110. Specifically, the control unit 80 acquires volume information V from the input unit 60.

[0091] In step S110, the control unit 80 acquires refrigerant information R and proceeds to step S120. Specifically, the control unit 80 acquires first refrigerant information R1 from the first detection unit 35 and second refrigerant information R2 from the second detection unit 36.

[0092] In step S120, the control unit 80 calculates the density ρ1 of the refrigerant based on the first refrigerant information R1 and proceeds to step S130. Specifically, the control unit 80 calculates the density ρ1 based on the pressure p1 and temperature t1.

[0093] In step S130, the control unit 80 calculates the density ρ2 of the refrigerant based on the second refrigerant information R2 and proceeds to step S140. Specifically, the control unit 80 calculates the density ρ2 based on the pressure p2 and temperature t2.

[0094] In step S140, the control unit 80 calculates the average density Da of the refrigerant in the utilization unit 10 and the first connecting pipe 40, and proceeds to step S150. Specifically, the control unit 80 calculates the average density Da using (Equation 1).

[0095] In step S150, the control unit 80 controls the opening of the first expansion valve 26 and the second expansion valve 33 so that the average density Da satisfies the above-described equation 1, and proceeds to step S100. In other words, in step S150, the control unit 80 controls the degree of superheating and subcooling in the refrigerant circuit 100 by controlling the opening of the first expansion valve 26 and the second expansion valve 33.

[0096] In this process, the control unit 80 calculates the internal volume v of the utilization unit 10 and the first connecting pipe 40 based on the volume information V. Specifically, the control unit 80 reads information regarding the internal volume of the utilization unit 10 from the storage device 81 based on the second volume information V2 regarding the identification of the utilization unit 10 received by the input unit 60. The control unit 80 also calculates the internal volume of the first connecting pipe 40 based on the first volume information V1 regarding the length of the first connecting pipe 40 and the information regarding the inner diameter of the first connecting pipe 40 recorded in the storage device 81. Subsequently, the control unit 80 calculates the internal volume v of the utilization unit 10 and the first connecting pipe 40 from the information regarding the internal volume of the utilization unit 10 and the internal volume of the first connecting pipe 40. If the input unit 60 receives the internal volume of the utilization unit 10 as the second volume information V2, the control unit 80 can use this directly to calculate the internal volume v. The threshold weight w is, for example, 0.152 (kg).

[0097] When the heating or cooling operation is stopped, the control unit 80 terminates the first control.

[0098] (3-4) Second control The heat pump device 1 can suppress further refrigerant leakage by executing a second control when refrigerant leakage occurs from the equipment constituting the utilization unit 10 during air conditioning operation.

[0099] (3-4-1) During heating operation When the refrigerant sensor 70 detects a refrigerant concentration above a predetermined level during heating operation, the control unit 80 fully opens the second expansion valve 33, closes the gas-side shutoff valve 34b, and stops the compressor 21 from running. This cuts off the supply of refrigerant to the portion of the refrigerant circuit 100 included in the utilization unit 10 (hereinafter also referred to as the utilization unit 10).

[0100] Subsequently, the control unit 80 closes the liquid-side shut-off valve 34a to terminate the second control. If refrigerant leakage continues after the refrigerant supply is shut off, the pressure in the utilization unit 10 will decrease, and there is a risk that the refrigerant stored in the receiver tank 24 will flow back into the utilization unit 10. By closing the liquid-side shut-off valve 34a, the backflow of refrigerant stored in the receiver tank 24 into the utilization unit 10 is suppressed.

[0101] (3-4-2) During cooling operation When the refrigerant sensor 70 detects a refrigerant concentration above a predetermined level during cooling operation, the control unit 80 fully opens the second expansion valve 33, closes the liquid-side shut-off valve 34a, and stops the compressor 21 from running. This cuts off the supply of refrigerant to the utilization unit 10.

[0102] Subsequently, the control unit 80 closes the gas-side shut-off valve 34b and terminates the second control.

[0103] (4) Features (4-1) The heat pump device 1 performs air conditioning operation on the air-conditioned space Ro. The heat pump device 1 comprises a utilization unit 10, a heat source unit 20, a sub-unit 30, a refrigerant circuit 100, and a control unit 80. The utilization unit 10 has a utilization heat exchanger 11. The heat source unit 20 has a heat source heat exchanger 22 and a compressor 21. The sub-unit 30 has a second expansion valve 33 that reduces the pressure of the flammable refrigerant flowing between the utilization unit 10 and the heat source unit 20. The refrigerant circuit 100 is configured by connecting the utilization unit 10 and the sub-unit 30 with a first connecting pipe 40, and connecting the sub-unit 30 and the heat source unit 20 with a second connecting pipe 50.

[0104] The control unit 80 controls the second expansion valve 33 based on volume information V relating to the volume of the first connecting pipe 40 and refrigerant information R relating to the temperature and pressure of the refrigerant flowing through the refrigerant circuit 100, and performs a first control to reduce the amount of refrigerant flowing through the utilization unit 10 and the first connecting pipe 40 to a predetermined amount or less.

[0105] In the heat pump device 1, regardless of the total amount of refrigerant filled into the refrigerant circuit 100, the amount of refrigerant flowing through the utilization unit 10 and the first connecting pipe 40 can be controlled to be below a predetermined amount. Therefore, even if refrigerant leaks from the utilization unit 10, the amount of leakage can be kept within a certain range, and the risk of ignition in the event of a refrigerant leak can be suppressed. Thus, the heat pump device 1 can reduce the risk in the event of a refrigerant leak while ensuring a sufficient amount of refrigerant can be filled.

[0106] The heat pump device 1 further includes a subunit 30 which comprises a liquid pipe 31 and a gas pipe 32, with a first connecting pipe 40 connected to one end and a second connecting pipe 50 connected to the other end, and a gas-side shut-off valve 34b that blocks the passage of refrigerant flowing through the gas pipe 32.

[0107] The heat pump device 1 can suppress further refrigerant leakage by closing the gas-side shut-off valve 34b when refrigerant leakage occurs from the utilization unit 10, thereby preventing the circulation of refrigerant from the heat source unit 20 to the utilization unit 10.

[0108] The heat pump device 1 includes refrigerant information, which includes first refrigerant information R1 and second refrigerant information R2. The first refrigerant information R1 is the temperature t1 and pressure p1 of the refrigerant flowing between the end 40aa of the first liquid connecting pipe 40a connected to the utilization unit 10 and the liquid side end of the heat source heat exchanger 22, which is connected to the liquid pipe 31. The second refrigerant information R2 is the temperature t2 and pressure p2 of the refrigerant flowing between the end 40ba of the first gas connecting pipe 40b connected to the utilization unit 10 and the compressor 21, which is connected to the gas pipe 32. In the first control, the control unit 80 controls the second expansion valve 33 based on the average density Da of the refrigerant in the utilization unit 10 and the first connecting pipe 40, which is calculated using the first refrigerant information R1 and the second refrigerant information R2.

[0109] The heat pump device 1 can control the second expansion valve 33 based on the average density Da obtained using the first refrigerant information and the second refrigerant information.

[0110] The heat pump device 1 has a subunit 30 which further includes a first detection unit 35 and a second detection unit 36. The first detection unit 35 detects first refrigerant information R1 between the end of the liquid piping 31 on the first liquid connecting pipe 40a side and the second expansion valve 33. The second detection unit 36 ​​detects second refrigerant information R2 between the end of the gas piping 32 on the first gas connecting pipe 40b side and the gas side shut-off valve 34b.

[0111] The heat pump device 1 includes volume information V, which comprises first volume information V1 relating to the length of the first connecting pipe 40 and second volume information V2 relating to the identification of the utilization unit 10.

[0112] The heat pump device 1 can control the second expansion valve 33 based on the first volume information V1 and the second volume information V2.

[0113] The heat pump device 1 includes a second volume information V2 which contains the model name of the utilization unit 10 or the internal volume of the utilization unit 10.

[0114] In the first control of the heat pump device 1, the control unit 80 controls the second expansion valve 33 such that the following equation 2 is satisfied, where Da is the average density of the refrigerant and v is the internal volume of the utilization unit 10 and the first connecting pipe 40. TIFF0007879476000003.tif12170

[0115] The heat pump device 1 can control the second expansion valve 33 based on the average density of the refrigerant, Da, and the internal volume v of the utilization unit 10 and the first connecting pipe 40.

[0116] (5) Variant (5-1) Variation 1 The heat pump device 1 may further perform a pump-down operation to recover the refrigerant from the portion of the refrigerant circuit 100 included in the utilization unit 10 to the portion of the refrigerant circuit 100 included in the heat source unit 20. The heat pump device 1 performs the pump-down operation, for example, as follows.

[0117] When the refrigerant sensor 70 detects a refrigerant concentration above a predetermined level during cooling operation, the control unit 80 fully opens the second expansion valve 33 and closes the liquid-side shut-off valve 34a. At this time, the control unit 80 continues to drive the compressor 21. As a result, the refrigerant in the refrigerant circuit 100 is drawn into the portion of the refrigerant circuit 100 included in the utilization unit 10 and recovered into the receiver tank 24.

[0118] Subsequently, when the refrigerant pressure in the suction section 21a of the compressor 21 falls below a predetermined threshold, the control unit 80 stops driving the compressor 21 and closes the gas-side shut-off valve 34b to terminate the pump-down operation.

[0119] Because the heat pump device 1 controls the amount of refrigerant flowing through the utilization unit 10 and the first connecting pipe 40 to be below a predetermined amount by the first control, the recovery of refrigerant into the portion included in the heat source unit 20 can be completed more quickly compared to when the first control is not performed.

[0120] In some of the components that make up the heat source unit 20, such as the compressor 21 and the four-way switching valve 23, it may not be possible to completely shut off the refrigerant flowing through the refrigerant circuit 100 due to structural reasons. As a result, the refrigerant recovered in the receiver tank 24 leaks from the high-pressure part to the low-pressure part of the refrigerant circuit 100 over time, and eventually becomes equalized in the refrigerant circuit 100 at the saturation pressure equivalent to the outside air. In the heat pump device 1, the liquid-side shut-off valve 34a and the gas-side shut-off valve 34b are closed when the pump-down operation is completed, so that the refrigerant that has been equalized in the part of the refrigerant circuit 100 included in the utilization unit 10 does not leak out of the utilization unit 10 over time after the pump-down operation is completed.

[0121] (5-2) Modification 2 The control unit 80 may be configured not to start air conditioning operation if there is no input of volume information V to the input unit 60.

[0122] The heat pump device 1 can suppress refrigerant leakage by not starting air conditioning operation when there is no input of volume information V necessary for controlling the second expansion valve 33.

[0123] (5-3) Modification 3 The second expansion valve 33 may be fully closable. In this case, the second expansion valve 33 can also function as a liquid-side shut-off valve 34a. Specifically, the control unit 80 may close the second expansion valve 33 when the refrigerant sensor 70 detects a refrigerant concentration above a predetermined level during air conditioning operation.

[0124] In the heat pump device 1 according to Modification 3, refrigerant leakage can be suppressed by the second expansion valve 33, making the liquid side shut-off valve 34a unnecessary. Therefore, the manufacturing cost of the heat pump device 1 is reduced.

[0125] (5-4) Modification 4 The heat pump device 1 may have multiple pairs of utilization units 10 and subunits 30 connected to a single heat source unit 20.

[0126] Figure 4 shows a schematic diagram of the heat pump device 1 according to Modification 3. In the heat pump device 1 according to Modification 3, one heat source unit 20 is connected to two utilization units 10 and two subunits 30. The structure of the heat source unit 20 and subunit 30 of the heat pump device 1 according to Modification 3 is the same as described above. For this reason, the illustration of the structure of the heat source unit 20 and subunit 30 in Figure 4 is omitted.

[0127] Although a detailed explanation will be omitted, in the first control, the control unit 80 of the heat pump device 1 according to the modified example 3 controls the second expansion valve 33 so that (Equation 1) is satisfied for each pair of utilization unit 10 and subunit 30.

[0128] (5-5) Variation 5 The pressure p1 during cooling operation may be detected by any of the pressure sensors 35d, 35e, and 35f. Pressure sensor 35d detects the pressure of the refrigerant in the liquid piping 31 between the second expansion valve 33 and the liquid-side shut-off valve 34a. Pressure sensor 35e detects the pressure of the refrigerant in the refrigerant piping connecting the second communication passage 24b of the receiver tank 24 and the second liquid communication piping 50a. Pressure sensor 35f detects the pressure of the refrigerant in the refrigerant piping connecting the second port 23b of the four-way switching valve 23 and the second gas communication piping 50b.

[0129] The temperature t1 during cooling operation may be detected by a temperature sensor 35g. The temperature sensor 35g detects the temperature of the refrigerant in the refrigerant piping that connects the second communication passage 24b of the receiver tank 24 to the second liquid communication pipe 50a.

[0130] The pressure p2 during cooling operation may be detected by a pressure sensor 36c. The pressure sensor 36c detects the pressure of the refrigerant in the refrigerant piping connecting the second port 23b of the four-way switching valve 23 and the second gas connecting pipe 50b.

[0131] The temperature t2 during cooling operation may be detected by a temperature sensor 36d. The temperature sensor 36d detects the temperature of the refrigerant in the refrigerant piping connecting the second port 23b of the four-way switching valve 23 and the second gas communication pipe 50b.

[0132] (5-6) Variation 6 In step S150 of the first control, the control unit 80 may control only the opening degree of the second expansion valve 33 so that the average density Da satisfies equation (Equation 1). In other words, in step S150, the control unit 80 may control the degree of superheating and subcooling in the refrigerant circuit 100 by controlling only the opening degree of the second expansion valve 33.

[0133] (5-7) Variation 7 Multiple threshold weights w may be set. For example, the threshold weights w may include a first threshold weight w1, a second threshold weight w2 greater than the first threshold weight w1, and a third threshold weight w3 greater than the second threshold weight w2. In this case, the control unit 80 increases the threshold weights w from the first threshold weight w1 to the third threshold weight w3 at predetermined time intervals from the start of the first control.

[0134] This prevents the weight of the refrigerant in the utilization unit 10 and the first connecting pipe 40 from exceeding the third threshold weight w3, which is the maximum threshold weight w (overshoot).

[0135] The third threshold weight w3 may be the same as the threshold weight w in the first embodiment, which is 152 grams.

[0136] <Second Embodiment> (1) Overall structure Next, we will describe the heat pump device 1a according to the second embodiment. Figure 5 is a schematic diagram of the heat pump device 1a. In the following, we will mainly describe the differences between the heat pump device 1 and the heat pump device 1a, and we may omit explanations of the same or corresponding features or well-known technologies.

[0137] The heat source unit 20 of the heat pump device 1a does not have the receiver tank 24 that the heat pump device 1 had. The heat source unit 20 of the heat pump device 1a further has an economizer heat exchanger 27 and an injection expansion valve 28. The heat source unit 20 of the heat pump device 1a has a compressor 121 instead of a compressor 21. The heat pump device 1a has a control unit 80a instead of a control unit 80.

[0138] (2) Detailed configuration (2-1) Compressor 121 The compressor 121 compresses the low-pressure refrigerant and the intermediate-pressure refrigerant in the refrigerant circuit 100, and then discharges them as high-pressure refrigerant in the refrigerant circuit 100. The compressor 121 has a first suction section 121a, a second suction section 121b, and a discharge section 121c. The compressor 121 is controlled by the control section 80a.

[0139] The compressor 121 compresses the low-pressure refrigerant drawn in from the first suction port 121a and the intermediate-pressure refrigerant drawn in from the second suction port 121b, and discharges them as high-pressure refrigerant from the discharge port 121c.

[0140] The first intake section 121a is connected to the second communication passage 25b of the accumulator 25. The second intake section 121b is connected to the second flow path 27b (described later) of the economizer heat exchanger 27. The discharge section 121c is connected to the first port 23a of the four-way switching valve 23.

[0141] (2-2) Economizer heat exchanger 27 The economizer heat exchanger 27 has a first flow path 27a and a second flow path 27b. The economizer heat exchanger 27 causes the refrigerant flowing through the first flow path 27a to exchange heat with the refrigerant flowing through the second flow path 27b.

[0142] The first flow path 27a is a flow path through which the refrigerant flows between the liquid-side end 22b of the heat source heat exchanger 22 and the end 50aa of the second liquid connecting pipe 50a on the heat source unit 20 side.

[0143] The second flow path 27b is a flow path through which the refrigerant that was diverted at the branching section 100a provided in the refrigerant piping connecting the end 50aa on the heat source unit 20 side of the second liquid communication pipe 50a and the first flow path 27a flows. The second flow path 27b is connected to the compressor 121 so that the refrigerant that has flowed out flows into the second suction section 121b.

[0144] (2-3) Injection expansion valve 28 The injection expansion valve 28 adjusts and reduces the flow rate of the refrigerant passing through it by changing its opening degree based on the instructions of the control unit 80a, thereby creating an intermediate pressure in the refrigerant circuit 100.

[0145] The injection expansion valve 28 reduces the pressure of the refrigerant flowing between the branch section 100a and the second flow path 27b of the economizer heat exchanger 27.

[0146] (2-4) Control unit 80a The difference between control unit 80a and control unit 80 is that control unit 80a is further connected to the compressor 121 and the injection expansion valve 28 so that it can send and receive control signals, etc. Figure 6 is a schematic diagram showing the connection relationship between control unit 80a and each part.

[0147] (3) Overall operation (3-1) Heating operation and cooling operation During heating and cooling operations, the control unit 80a controls the opening degree of the injection expansion valve 28. The control and operation of other equipment are the same as those of the heat pump unit 1, so their explanation is omitted.

[0148] The refrigerant branched off at branching section 100a is depressurized by the injection expansion valve 28 to an intermediate pressure before flowing into the second flow path 27b of the economizer heat exchanger 27. The high-pressure liquid-phase refrigerant flowing out from the liquid-side end 22b of the heat source heat exchanger 22 and passing through the first flow path 27a of the economizer heat exchanger 27 releases heat to the refrigerant flowing into the second flow path 27b. The refrigerant flowing out from the second flow path 27b is then drawn back into the compressor 21 from the first suction section 121a.

[0149] (3-2) First control The difference between the first control performed by heat pump device 1 and the first control performed by heat pump device 1a is that in step S150, the control unit 80 controls the injection expansion valve 28 instead of the first expansion valve 26. Specifically, in step S150, the control unit 80 of heat pump device 1a controls the discharge pipe temperature and discharge superheat of the compressor 121 in the refrigerant circuit 100 by controlling the opening degree of the injection expansion valve 28 and the opening degree of the second expansion valve 33.

[0150] <Third Embodiment> (1) Overall structure Next, a heat pump device 1b according to the third embodiment will be described. Figure 7 is a schematic diagram of the heat pump device 1b. In the following, the differences between the heat pump device 1 and the heat pump device 1b will be the main focus of the description, and descriptions of identical or corresponding features or well-known technologies may be omitted.

[0151] The heat pump device 1b further includes an auxiliary unit 90. The heat pump device 1b includes a control unit 80b instead of a control unit 80.

[0152] (2) Detailed configuration (2-1) Auxiliary unit 90 The auxiliary unit 90 includes an auxiliary compressor 91, a refrigerant cooler 92, an auxiliary expansion valve 93, and an auxiliary heat exchanger 94. The auxiliary compressor 91, refrigerant cooler 92, auxiliary expansion valve 93, and auxiliary heat exchanger 94 are connected by refrigerant piping to form an auxiliary refrigerant circuit 110. The auxiliary refrigerant circuit 110 is filled with a natural refrigerant such as carbon dioxide.

[0153] (2-1-1) Auxiliary compressor 91 The auxiliary compressor 91 compresses the low-pressure refrigerant in the auxiliary refrigerant circuit 110 and then discharges it as high-pressure refrigerant in the auxiliary refrigerant circuit 110. The auxiliary compressor 91 has an intake section 91a and a discharge section 91b. The auxiliary compressor 91 is controlled by the control unit 80b.

[0154] The auxiliary compressor 91 compresses the low-pressure refrigerant drawn in from the suction section 91a and discharges it as high-pressure refrigerant from the discharge section 91b. The suction section 21a is connected to the first flow path 92a (described later) of the refrigerant cooler 92. The discharge section 91b is connected to the auxiliary heat exchanger 94.

[0155] (2-1-2) Refrigerant cooler 92 The refrigerant cooler 92 facilitates heat exchange between the refrigerant flowing through the refrigerant circuit 100 and the refrigerant flowing through the auxiliary refrigerant circuit 110. The refrigerant cooler 92 has a first flow path 92a and a second flow path 92b.

[0156] The first flow path 92a is a flow path through which the refrigerant flowing out from the auxiliary expansion valve 93 passes. One end of the first flow path 92a is connected to the suction section 91a of the auxiliary compressor 91, and the other end is connected to the liquid side end 94b of the auxiliary heat exchanger 94.

[0157] The second flow path 92b is a flow path through which the refrigerant passing through the second liquid connecting pipe 50a passes.

[0158] (2-1-3) Auxiliary expansion valve 93 The auxiliary expansion valve 93 adjusts and reduces the flow rate of the refrigerant passing through it by changing its opening degree based on instructions from the control unit 80b.

[0159] The auxiliary expansion valve 93 is installed in the refrigerant piping that connects the first flow path 92a of the refrigerant cooler 92 to the auxiliary heat exchanger 94.

[0160] (2-1-4) Auxiliary heat exchanger 94 The auxiliary heat exchanger 94 causes the refrigerant circulating in the auxiliary refrigerant circuit 110 to exchange heat with, for example, the outdoor air. The auxiliary heat exchanger 94 has a gas-side end 94a and a liquid-side end 94b.

[0161] The gas-side end 94a is connected to the discharge section 91b of the auxiliary compressor 91. The liquid-side end 94b is connected to the first flow path 92a of the refrigerant cooler 92.

[0162] (2-2) Control unit 80b The difference between the control unit 80b and the control unit 80 is that the control unit 80b is further connected to the auxiliary compressor 91 and the auxiliary expansion valve 93 so that it can send and receive control signals, etc. Figure 8 is a schematic diagram showing the connection relationship between the control unit 80b and each part.

[0163] (3) Overall operation (3-1) Heating operation During heating operation, the auxiliary unit 90 is kept in a stopped state. The control and operation of the other equipment are the same as those of the heat pump unit 1, so a description is omitted.

[0164] (3-2) Cooling operation During cooling operation, the control unit 80b drives the auxiliary compressor 91 as needed and controls the opening degree of the auxiliary expansion valve 93.

[0165] The auxiliary compressor 91 draws in the low-pressure gas phase refrigerant from the auxiliary refrigerant circuit 110 through the suction port 91a and discharges it as high-pressure gas phase refrigerant through the discharge port 91b. The high-pressure gas phase refrigerant that flows into the auxiliary heat exchanger 94 from the gas side end 94a condenses by releasing heat into the outside air to become high-pressure liquid phase refrigerant. The high-pressure liquid phase refrigerant that flows out from the liquid side end 94b of the auxiliary heat exchanger 94 passes through the auxiliary expansion valve 93 and then flows into the first flow path 92a of the refrigerant cooler 92. The auxiliary expansion valve 93, set to an appropriate opening degree, reduces the pressure of the high-pressure liquid phase refrigerant to make it a low-pressure gas-liquid two-phase refrigerant. The refrigerant that flows into the first flow path 92a of the refrigerant cooler 92 evaporates by absorbing heat from the refrigerant passing through the second flow path 92b to become low-pressure gas phase refrigerant. The refrigerant that flows out from the second flow path 92b of the refrigerant cooler 92 is drawn back into the auxiliary compressor 91 from the suction port 91a.

[0166] The control and operation of the other equipment are the same as those of the heat pump unit 1, so their explanation will be omitted.

[0167] (3-3) First control The difference between the first control performed by heat pump device 1 and the first control performed by heat pump device 1b is that in step S150, the control unit 80 controls the auxiliary expansion valve 93. Specifically, in step S150, the control unit 80b of heat pump device 1b controls the degree of subcooling in the refrigerant circuit 100 by controlling the opening degree of the auxiliary expansion valve 93 and the opening degree of the second expansion valve 33. <Conclusion> While embodiments of this disclosure have been described above, it should be understood that various modifications to the form and details are possible without departing from the spirit and scope of this disclosure as described in the claims. [Explanation of symbols]

[0168] 1: Heat pump device 1a: Heat pump device 1b: Heat pump device 10: Units used 11: Use heat exchanger 20: Heat source unit 21: Compressor 22:Heat source heat exchanger 22b: Liquid side end 30: Subunit 31: Liquid Piping 32: Gas piping 35: First detection unit 36: Second detection unit 40: First connecting pipe 40aa: End 40ba: end 50: Second connecting pipe 60: Input section 70: Refrigerant sensor 80: Control Unit 80a: Control Unit 80b: Control Unit 100: Refrigerant circuit 121: Compressor p1: Pressure p2: Pressure R: Refrigerant information R1: Refrigerant Information (First Stage) R2: Second Refrigerant Information Ro: Air-conditioned space t1 :Temperature t2 :Temperature v :Inner volume V: Volume information V1: 1st volume information V2 :Second volume information Da: average density [Prior art documents] [Patent Documents]

[0169] [Patent Document 1] Patent No. 2016-166680

Claims

1. A heat pump system (1, 1a, 1b) that performs air conditioning operation for a space to be air-conditioned (Ro), A utilization unit (10) having a utilization heat exchanger (11), A heat source unit (20) having a heat source heat exchanger (22) and compressors (21, 121), A subunit (30) having an expansion mechanism for reducing the pressure of the flammable refrigerant flowing between the utilization unit (10) and the heat source unit (20), A refrigerant circuit (100) is formed by connecting the utilization unit (10) and the subunit (30) with a first connecting pipe (40), and connecting the subunit (30) and the heat source unit (20) with a second connecting pipe (50), Control units (80, 80a, 80b) and Equipped with, The expansion mechanism adjusts and reduces the flow rate of the refrigerant passing through its interior by changing the degree of opening. The control units (80, 80a, 80b) are Based on volume information (V) relating to the volume of the first connecting pipe (40) and refrigerant information (R) relating to the temperature (t1) and pressure (p1) of the refrigerant flowing through the refrigerant circuit (100), the expansion mechanism is controlled to perform a first control that reduces the amount of refrigerant flowing through the utilization unit (10) and the first connecting pipe (40) to a predetermined amount or less. Heat pump devices (1, 1a, 1b).

2. The aforementioned subunit (30) is A liquid pipe (31) and a gas pipe (32) are connected to one end of the first connecting pipe (40) and to the other end of the second connecting pipe (50), A shut-off mechanism that blocks the passage of the refrigerant flowing through the gas pipe (32) and It further possesses, The heat pump device (1, 1a, 1b) according to claim 1.

3. The aforementioned refrigerant information (R) is, First refrigerant information (R1) is the temperature (t1) and pressure (p1) of the refrigerant flowing between the end (40aa) of the first connecting pipe (40a) connected to the utilization unit (10) and the liquid side end (22b) of the heat source heat exchanger (22), and Second refrigerant information (R2), which is the temperature (t2) and pressure (p2) of the refrigerant flowing between the end (40ba) of the first connecting pipe (40b) connected to the utilization unit (10) and the compressor (21, 121), and the gas pipe (32) and the second refrigerant information (R2). Includes, The control units (80, 80a, 80b) are In the first control, the expansion mechanism is controlled based on the average density (Da) of the refrigerant in the utilization unit (10) and the first connecting pipe (40) calculated using the first refrigerant information (R1) and the second refrigerant information (R2). The heat pump device (1, 1a, 1b) according to claim 2.

4. The aforementioned subunit (30) is A first detection unit (35) detects the first refrigerant information (R1) between the end of the liquid piping (31) on the first connecting piping (40a) side and the expansion mechanism, A second detection unit (36) for detecting the second refrigerant information (R2) between the end of the gas piping (32) on the first connecting piping (40b) side and the shut-off mechanism, It further possesses, The heat pump device (1, 1a, 1b) according to claim 3.

5. The volume information (V) is, This includes first volume information (V1) relating to the length of the first connecting pipe (40) and second volume information (V2) relating to the identification of the utilization unit (10), The heat pump device (1, 1a, 1b) according to claim 1.

6. The second volume information (V2) is, The model name of the utilization unit (10) or the internal volume (v) of the utilization unit (10) is included, The heat pump device (1, 1a, 1b) according to claim 5.

7. The control units (80, 80a, 80b) are In the first control, when the average density of the refrigerant is Da and the internal volume of the utilization unit (10) and the first connecting pipe (40) is v, the expansion mechanism is controlled to satisfy the following equation: The heat pump device (1, 1a, 1b) according to claim 3.

8. Further, a pump-down operation is performed to recover the refrigerant from the portion of the refrigerant circuit (100) included in the utilization unit (10) to the portion of the refrigerant circuit (100) included in the heat source unit (20). The heat pump device (1, 1a, 1b) according to claim 3.

9. The system further includes an input unit (60) that receives the volume information (V), The control units (80, 80a, 80b) are If no volume information (V) is input, the air conditioning operation will not be started. The heat pump device (1, 1a, 1b) according to claim 1.

10. The system further includes a refrigerant sensor (70) for detecting the refrigerant in the air-conditioned space (Ro), The control units (80, 80a, 80b) are The shut-off mechanism is controlled based on the detection result of the refrigerant sensor (70). The heat pump device (1, 1a, 1b) according to claim 3.

11. The aforementioned expansion mechanism is It can be completely closed. A heat pump device (1) according to any one of claims 1 to 10.

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