Refrigeration cycle device

Abstract

Provided is a refrigeration cycle device which can handle leakage of a refrigerant from utilization units while reducing a number of parts. An air conditioner (100) comprises: a heat source unit (10) having a compressor (12) and a heat source heat exchanger (16); a plurality of utilization units (30) each having a utilization heat exchanger (32); gas piping (GP) that connects the compressor of the heat source unit and the utilization heat exchangers of the plurality of utilization units; and a shut-off valve (52). The gas piping includes a first pipe (4a) extending from the heat source unit, second pipes (4b) extending from the utilization units, and a branch portion (4c) at which the first pipe branches into the plurality of second pipes. The shut-off valve is disposed in the gas pipes at a location closer to the heat source unit than the branch portion is. Each of the utilization units has a utilization expansion valve (36), the opening of which is adjustable and which is provided in a liquid pipe (LP) connecting the utilization heat exchanger of the utilization unit and the heat source heat exchanger of the heat source unit.

Description

Refrigeration Cycle Equipment

[0001] The present disclosure relates to a refrigeration cycle device.

[0002] As disclosed in Patent Document 1 (Patent No. 6927315), a refrigeration cycle device is known in which a shut-off valve is provided in each of a plurality of utilization units having a utilization heat exchanger and a utilization expansion valve, and the shut-off valve is closed in the event of a refrigerant leak.

[0003] In such a refrigeration cycle apparatus, a large number of shutoff valves are required in the refrigerant piping in accordance with the number of utilization units.

[0004] A refrigeration cycle apparatus according to a first aspect includes a heat source unit, a plurality of utilization units, a gas pipe, and a first shutoff valve. The heat source unit has a compressor and a heat source heat exchanger. Each of the plurality of utilization units has a utilization heat exchanger. The gas pipe connects the compressor of the heat source unit to the utilization heat exchangers of the plurality of utilization units. The gas pipe includes a first pipe extending from the heat source unit, a second pipe extending from the utilization unit, and a branching section that branches the first pipe into a plurality of second pipes. The first shutoff valve is disposed in the gas pipe closer to the heat source unit than the branching section. Each utilization unit has an adjustable opening second shutoff valve provided in a liquid pipe that connects the utilization heat exchanger of that utilization unit to the heat source heat exchanger of the heat source unit.

[0005] In the refrigeration cycle apparatus of the first aspect, a first shutoff valve common to a plurality of utilization units is provided in the gas pipe, and a second shutoff valve (a shutoff valve also used as an expansion valve) with an adjustable opening is provided for each utilization unit. Therefore, the refrigeration cycle apparatus of the first aspect can respond to refrigerant leakage from the utilization units while reducing the number of parts.

[0006] A refrigeration cycle apparatus according to a second aspect is the refrigeration cycle apparatus according to the first aspect, wherein the first shutoff valve is a flow rate adjustment valve whose opening degree is adjustable.

[0007] In this refrigeration cycle device, the first shutoff valve can also be used for flow rate adjustment purposes in addition to being used as a shutoff valve, which makes it possible to reduce the number of parts.

[0008] A refrigeration cycle apparatus according to a third aspect is the refrigeration cycle apparatus according to the first or second aspect, wherein each utilization unit further includes a refrigerant sensor, and when the refrigerant sensor of one utilization unit detects a refrigerant leak, the first shutoff valve and second shutoff valves of a plurality of utilization units connected to the heat source unit via gas pipes via the first shutoff valve are closed.

[0009] In the refrigeration cycle apparatus of the third aspect, it is possible to reduce the number of parts and to prevent the concentration of leaked refrigerant from becoming high in the space where the utilization units are installed.

[0010] A fourth aspect of the refrigeration cycle apparatus is the refrigeration cycle apparatus of the third aspect, wherein the utilization units further include a controller. When a refrigerant sensor of each utilization unit detects a refrigerant leak, it sends a signal to the controller of the utilization unit in which the refrigerant sensor is installed. The controller of the utilization unit in which the refrigerant sensor that detected the refrigerant leak is installed sends a command to close the second shutoff valve to the controllers of other utilization units that are connected to the heat source unit via gas piping via the first shutoff valve, along with the utilization unit in which the leak was detected.

[0011] In the refrigeration cycle device of the fourth aspect, the utilization unit receives a command to close the second shut-off valve from a utilization unit located nearby without going through the heat source unit, so that the flow of refrigerant from the heat source unit to the utilization unit can be shut off early in the event of a refrigerant leak.

[0012] A refrigeration cycle apparatus according to a fifth aspect is the refrigeration cycle apparatus according to the fourth aspect, wherein the utilization unit stops operation when it receives a command to close the second shutoff valve.

[0013] In this refrigeration cycle apparatus, the operation of the utilization units is stopped, which makes it easier to prevent the refrigerant flowing out from the utilization units from diffusing into the space in which the utilization units are installed.

[0014] FIG. 1 is a schematic configuration diagram of an air conditioner according to a first embodiment. FIG. 2 is a control block diagram of the air conditioner of FIG. 1. FIG. 3 is a sequence chart illustrating the exchange of signals between each control unit and the operation of each unit when a refrigerant sensor in one user unit of the air conditioner of FIG. 1 detects a leak. FIG. 4 is a diagram illustrating the operation of the air conditioner 100 when a refrigerant leak is detected in one user unit in Modification A. FIG. 5 is a refrigerant circuit diagram within a heat source unit of an air conditioner according to a second embodiment. FIG. 6 is a refrigerant circuit diagram of a portion other than the heat source unit of an air conditioner according to the second embodiment. FIG. 7 is a control block diagram of an air conditioner according to the second embodiment. FIG. 8 is a sequence chart illustrating the exchange of signals between each control unit and the operation of each unit when a refrigerant sensor in one user unit of the air conditioner according to the second embodiment detects a leak.

[0015] An embodiment of a refrigeration cycle device will be described with reference to the drawings.

[0016] First Embodiment (1) Overall Configuration A first embodiment of a refrigeration cycle device will be described below, which is an air conditioner 100. The refrigeration cycle device of the present disclosure is not limited to an air conditioner, and may also be a hot water supply device or a floor heating device.

[0017] An air conditioner 100 according to the first embodiment will be described with reference to the schematic configuration diagram of FIG.

[0018] The air conditioner 100 is a device that conditions the air of multiple air-conditioned spaces within a building. The air conditioner 100 mainly has a heat source unit 10, multiple utilization units 30, one shutoff valve unit 50 shared by the multiple utilization units 30, and a control unit 70 (see FIG. 1). Note that the number of utilization units 30 depicted in FIG. 1 does not limit the number of utilization units 30 that the air conditioner 100 has.

[0019] As shown in Fig. 1 , the heat source unit 10 and the utilization units 30 are connected by communication pipes 2 and 4. By connecting the heat source unit 10 and the utilization units 30 by the communication pipes 2 and 4, a refrigerant circuit 90 is formed, which includes a compressor 12, a heat source heat exchanger 16, a heat source expansion valve 18, a utilization expansion valve 36, a utilization heat exchanger 32, etc., which will be described later. As shown in Fig. 1 , a shutoff valve unit 50 is provided in the communication pipe 4. The communication pipe 4 is a gas communication pipe through which refrigerant flows from the utilization units 30 to the heat source unit 10 during cooling operation, and through which refrigerant flows from the heat source unit 10 to the utilization units 30 during heating operation. The control unit 70 controls the operation of each part of the air conditioner 100.

[0020] (2) Detailed Configuration (2-1) Usage Unit The usage unit 30 is installed in the air-conditioned space to be air-conditioned. The usage unit 30 may be, for example, a ceiling-embedded type, a ceiling-suspended type, a wall-mounted type, or a floor-standing type unit. In this embodiment, the following description will be given using the example where the usage unit 30 is a ceiling-embedded type.

[0021] Each utilization unit 30 mainly includes a utilization heat exchanger 32, a utilization fan 34, a utilization expansion valve 36, a utilization control unit 72, a refrigerant sensor 38, and a casing 31 that houses these components.

[0022] In the utilization heat exchanger 32, heat exchange occurs between the refrigerant flowing inside the utilization heat exchanger 32 and the air in the air-conditioned space. The utilization heat exchanger 32 is, for example, a fin-and-tube type heat exchanger having a plurality of heat transfer fins and a plurality of heat transfer tubes.

[0023] The utilization fan 34 supplies air taken in from the air-conditioned space to the utilization heat exchanger 32. The utilization fan 34 is, for example, a centrifugal fan such as a turbo fan or a sirocco fan. The utilization fan 34 is driven by a motor (not shown).

[0024] The utilization expansion valve 36 is an example of a second shutoff valve. Here, the pipe connecting the liquid end of the utilization heat exchanger 32 and the connection pipe 2, the connection pipe 2, and the liquid refrigerant pipe 28d are collectively referred to as the liquid pipe LP, and the utilization expansion valve 36 is provided in the liquid pipe LP. In particular, in this embodiment, the utilization expansion valve 36 is provided in the pipe connecting the connection pipe 2 and the liquid side end of the utilization heat exchanger 32, and is a mechanism for adjusting the pressure and flow rate of the refrigerant. The utilization expansion valve 36 is an electrically operated valve (electronic expansion valve) whose opening is adjustable. The utilization expansion valve 36 is also used as a shutoff valve in the event of a refrigerant leak, and is a valve with a small leakage amount when closed. For example, the utilization expansion valve 36 is configured to have a leakage amount of 300 cm when closed. ３ / min (air, ΔP = 1.0 MPa) or less.

[0025] The refrigerant sensor 38 is a sensor that detects refrigerant leakage and is provided, for example, near the utilization heat exchanger 32.

[0026] The usage control unit 72 has a control and arithmetic device and a storage device. The control and arithmetic device is a processor such as a CPU or GPU. The storage device is a storage medium such as a RAM, a ROM, or a flash memory. The control and arithmetic device reads out a program stored in the storage device and performs predetermined arithmetic processing in accordance with the program, thereby cooperating with a heat source control unit 74 of the heat source unit 10 and a valve control unit 76 of the shut-off valve unit 50 to control the operation of various devices in the air conditioner 100 as the control unit 70. The functions of the control unit 70 will be described later.

[0027] (2-2) Heat Source Unit The heat source unit 10 is installed on the roof or in a machine room of the building in which the air conditioner 100 is installed. As shown in Fig. 1, the heat source unit 10 mainly includes a compressor 12, a flow path switching valve 14, a heat source heat exchanger 16, a heat source expansion valve 18, an accumulator 20, a heat source fan 22, a liquid shut-off valve 24, a gas shut-off valve 26, and a heat source control unit 74. The heat source unit 10 also includes a suction pipe 28a, a discharge pipe 28b, gas refrigerant pipes 28c and 28e, and a liquid refrigerant pipe 28d.

[0028] The suction pipe 28a connects the flow path switching valve 14 and the suction side of the compressor 12. The accumulator 20 is provided on the suction pipe 28a. The discharge pipe 28b connects the discharge side of the compressor 12 and the flow path switching valve 14. The gas refrigerant pipe 28c connects the flow path switching valve 14 and the gas side end of the heat source heat exchanger 16. The liquid refrigerant pipe 28d connects the liquid side end of the heat source heat exchanger 16 and the connection pipe 2. The heat source expansion valve 18 is provided on the liquid refrigerant pipe 28d. A liquid stop valve 24 is provided at the connection between the liquid refrigerant pipe 28d and the connection pipe 2. The gas refrigerant pipe 28e connects the flow path switching valve 14 and the connection pipe 4. A gas stop valve 26 is provided at the connection between the gas refrigerant pipe 28e and the connection pipe 4. The liquid stop valve 24 and the gas stop valve 26 are valves that are opened and closed manually.

[0029] The compressor 12 draws in low-pressure refrigerant in a refrigeration cycle through a suction pipe 28a, compresses the refrigerant using a compression mechanism (not shown), and discharges the compressed high-pressure refrigerant in the refrigeration cycle to a discharge pipe 28b. The compressor 12 is, for example, a rotary or scroll type positive displacement compressor. The compression mechanism of the compressor 12 is driven by a motor (not shown). The rotation speed of the motor of the compressor 12 can be controlled by an inverter.

[0030] The flow path switching valve 14 is a mechanism that switches the refrigerant flow path between a first state and a second state. In the first state, the flow path switching valve 14 connects the suction pipe 28a to the gas refrigerant pipe 28e and the discharge pipe 28b to the gas refrigerant pipe 28c, as shown by solid lines in the flow path switching valve 14 in Fig. 1. In the second state, the flow path switching valve 14 connects the suction pipe 28a to the gas refrigerant pipe 28c and the discharge pipe 28b to the gas refrigerant pipe 28e, as shown by dashed lines in the flow path switching valve 14 in Fig. 1. The flow path switching valve 14 is, for example, a four-way switching valve.

[0031] During cooling operation, the flow path switching valve 14 sets the refrigerant flow path to the first state. At this time, the refrigerant discharged from the compressor 12 flows through the refrigerant circuit 90 in the order of the heat source heat exchanger 16, the heat source expansion valve 18, the utilization expansion valve 36, and the utilization heat exchanger 32, and then returns to the compressor 12. In the first state, the heat source heat exchanger 16 functions as a condenser, and the utilization heat exchanger 32 functions as an evaporator.

[0032] During heating operation, the flow path switching valve 14 sets the refrigerant flow path to the second state. At this time, the refrigerant discharged from the compressor 12 flows through the refrigerant circuit 90 in the order of the utilization heat exchanger 32, utilization expansion valve 36, heat source expansion valve 18, and heat source heat exchanger 16, and then returns to the compressor 12. In the second state, the heat source heat exchanger 16 functions as an evaporator, and the utilization heat exchanger 32 functions as a condenser.

[0033] The heat source heat exchanger 16 exchanges heat between the refrigerant flowing inside the heat source heat exchanger 16 and the air around the heat source unit 10. The heat source heat exchanger 16 is, for example, a fin-and-tube heat exchanger having a plurality of heat transfer fins and a plurality of heat transfer tubes.

[0034] The heat-source expansion valve 18 is a mechanism for adjusting the pressure and flow rate of the refrigerant flowing through the liquid refrigerant pipe 28 d. As shown in Fig. 1, the heat-source expansion valve 18 is provided in the liquid refrigerant pipe 28 d. The heat-source expansion valve 18 is an electrically operated valve (electronic expansion valve) whose opening degree can be adjusted.

[0035] The accumulator 20 is a container provided in the suction pipe 28a and having a gas-liquid separation function that separates the refrigerant flowing in into the accumulator 20 into gas refrigerant and liquid refrigerant. The refrigerant flowing in the accumulator 20 is separated into gas refrigerant and liquid refrigerant, and the gas refrigerant that collects in the upper space flows into the compressor 12.

[0036] The heat source fan 22 supplies air around the heat source unit 10 to the heat source heat exchanger 16. The heat source fan 22 is, for example, an axial flow fan such as a propeller fan. The heat source fan 22 is driven by a motor (not shown).

[0037] The heat source control unit 74 has a control and arithmetic device and a storage device. The control and arithmetic device is a processor such as a CPU or GPU. The storage device is a storage medium such as a RAM, a ROM, or a flash memory. The control and arithmetic device reads out a program stored in the storage device and performs predetermined arithmetic processing in accordance with the program, thereby cooperating with the usage control unit 72 of the usage unit 30 and the valve control unit 76 of the shut-off valve unit 50 to control the operation of various devices in the air conditioner 100 as the control unit 70. The functions of the control unit 70 will be described later.

[0038] (2-3) Shut-off Valve Unit The communication pipe 4, the gas refrigerant pipe 28e, and the suction pipe 28a or the discharge pipe 28b constitute the gas pipe GP in the claims. The gas pipe GP connects the compressor 12 of the heat source unit 10 to the utilization heat exchangers 32 of the multiple utilization units 30. The gas pipe GP includes a first pipe 4a extending from the heat source unit 10, a second pipe 4b extending from the utilization unit 30, and a branch section 4c that branches the first pipe 4a into multiple second pipes 4b. The first pipe 4a is a section of the communication pipe 4 that connects the heat source unit 10 and the branch section 4c. The second pipe 4b is a section of the communication pipe 4 that connects the utilization unit 30 and the branch section 4c.

[0039] The shutoff valve unit 50 is disposed in the first pipe 4a of the communication pipe 4. The shutoff valve unit 50 has a shutoff valve 52 as an example of a first shutoff valve disposed in the gas pipe GP closer to the heat source unit 10 than the branching portion 4c. One shutoff valve unit 50 is provided corresponding to the plurality of utilization units 30. In this embodiment, one shutoff valve unit 50 is provided for all the utilization units 30. The shutoff valve unit 50 is a unit that shuts off the flow of refrigerant in the event of a refrigerant leak from the corresponding utilization unit 30, for example.

[0040] The shutoff valve unit 50 is disposed, for example, outside the air-conditioned space. For example, the shutoff valve unit 50 is disposed in the space above the ceiling of the air-conditioned space or in the space under the floor of the air-conditioned space. The shutoff valve unit 50 is also disposed in the space above the ceiling of a corridor adjacent to the air-conditioned space. The installation location of the shutoff valve unit 50 is not limited to the locations exemplified above, and may be determined as appropriate.

[0041] The shutoff valve unit 50 mainly includes a shutoff valve 52 , a casing 54 , and a valve control section 76 .

[0042] The shutoff valve 52 is a valve that has a small leakage amount when closed. For example, the shutoff valve 52 has a leakage amount of 300 cm ３ / min (air, ΔP=1.0 MPa) or less. However, the type of valve is not limited to a solenoid valve, and may be an electrically operated valve or the like that is capable of adjusting the opening degree.

[0043] The casing 54 is a housing that houses the shutoff valve 52. A moisture-proof material is disposed inside the casing 54, which prevents condensation from forming around the shutoff valve 52.

[0044] The valve control unit 76 has a control and arithmetic device and a storage device. The control and arithmetic device is a processor such as a CPU or GPU. The storage device is a storage medium such as a RAM, a ROM, or a flash memory. The control and arithmetic device reads out a program stored in the storage device and performs predetermined arithmetic processing in accordance with the program, thereby cooperating with the usage control unit 72 of the usage unit 30 and the heat source control unit 74 of the heat source unit 10 to control the operation of various devices in the air conditioner 100 as the control unit 70. The functions of the control unit 70 will be described later.

[0045] (2-4) Control Unit The control unit 70 is made up of a usage control unit 72, a heat source control unit 74, and a valve control unit 76. The control unit 70 controls the overall operation of the air conditioner 100 by causing the control and arithmetic devices of the usage control unit 72, the heat source control unit 74, and the valve control unit 76 to execute programs stored in their respective storage devices.

[0046] FIG. 2 is a control block diagram of the air conditioner 100 in this embodiment.

[0047] 2, the control unit 70 is electrically connected to the utilization expansion valves 36, utilization fans 34, and refrigerant sensors 38 of each of the multiple utilization units 30, the compressor 12, flow path switching valve 14, heat source expansion valve 18, and heat source fan 22 of the heat source unit 10, and the shutoff valves 52 of each of the multiple shutoff valve units 50. The control unit 70 is also electrically connected to various sensors that measure the temperature and pressure of the refrigerant, the temperature of the air in the air-conditioned space, the outside air temperature, etc. The control unit 70 controls the operation of the various devices of the air conditioner 100 based on control signals received by the utilization units 30 from an operation remote control (not shown), measurement signals from the various sensors, etc.

[0048] The control unit 70 mainly performs cooling and heating operations, and also has a function of preventing refrigerant leakage.

[0049] (2-5-1) Cooling Operation When the control unit 70 receives a command to perform cooling operation, for example, from an operation remote control via the utilization unit 30, it switches the flow path switching valve 14 to the first state and starts operation of the compressor 12. In addition, based on the measurement results of sensors that measure the temperature and pressure of the refrigerant, which are provided in the refrigerant circuit 90, it appropriately controls the rotation speed of the motor of the compressor 12 and the openings of the heat source expansion valve 18 and the utilization expansion valve 36. During cooling operation, the shutoff valve 52 is controlled to be fully open.

[0050] The flow of refrigerant in the refrigerant circuit 90 will now be described. When the compressor 12 starts operating, low-pressure gas refrigerant in the refrigeration cycle (hereinafter simply referred to as low-pressure) is drawn into the compressor 12 and compressed by the compression mechanism of the compressor 12 to become high-pressure gas refrigerant in the refrigeration cycle (hereinafter simply referred to as high-pressure). The high-pressure gas refrigerant is sent to the heat-source heat exchanger 16 via the flow path switching valve 14, where it exchanges heat with the air around the heat source unit 10 supplied by the heat-source fan 22, condensing to become high-pressure liquid refrigerant. The high-pressure liquid refrigerant flows through the liquid refrigerant pipe 28d and passes through the heat-source expansion valve 18. The high-pressure liquid refrigerant sent to the utilization unit 30 is reduced in pressure by the utilization expansion valve 36 to near the suction pressure of the compressor 12, becoming a two-phase gas-liquid refrigerant and being sent to the utilization heat exchanger 32. In the utilization heat exchanger 32, the two-phase gas-liquid refrigerant exchanges heat with the air in the air-conditioned space supplied to the utilization heat exchanger 32 by the utilization fan 34, evaporating to become a low-pressure gas refrigerant. The low-pressure gas refrigerant flowing out from the multiple utilization units 30 join together and is sent to the heat source unit 10 via the communication pipe 4 and the shutoff valve unit 50, and flows into the accumulator 20 via the flow path switching valve 14. The low-pressure gas refrigerant that has flowed into the accumulator 20 is again sucked into the compressor 12. The temperature of the air supplied to the utilization heat exchanger 32 is lowered by heat exchange with the refrigerant flowing through the utilization heat exchanger 32, and the cooled air is blown into the air-conditioned space.

[0051] (2-5-2) Heating Operation When the control unit 70 receives a command to perform heating operation, for example, from the operation remote control via the utilization unit 30, it switches the flow path switching valve 14 to the second state and starts operation of the compressor 12. In addition, based on the measurement results of sensors that measure the temperature and pressure of the refrigerant provided in the refrigerant circuit 90, it appropriately controls the rotation speed of the motor of the compressor 12 and the openings of the heat source expansion valve 18 and the utilization expansion valve 36. During heating operation, the shutoff valve 52 is controlled to be fully open.

[0052] The flow of refrigerant in the refrigerant circuit 90 will now be described. When the compressor 12 is started, low-pressure gas refrigerant is drawn into the compressor 12 and compressed by the compressor 12 to become high-pressure gas refrigerant. The high-pressure gas refrigerant passes through the shut-off valve unit 50 and is sent to the utilization heat exchanger 32 via the flow path switching valve 14. It condenses and becomes high-pressure liquid refrigerant through heat exchange with air in the air-conditioned space that is supplied to the utilization heat exchanger 32 by the utilization fan 34. The temperature of the air supplied to the utilization heat exchanger 32 increases through heat exchange with the refrigerant flowing through the utilization heat exchanger 32, and the heated air is blown into the air-conditioned space. The high-pressure liquid refrigerant that has passed through the utilization heat exchanger 32 is decompressed in the utilization expansion valve 36. The decompressed liquid refrigerant is sent to the heat source unit 10 via the connection pipe 2 and flows into the liquid refrigerant pipe 28d. The refrigerant flowing through the liquid refrigerant pipe 28d is decompressed by the heat source expansion valve 18 to near the suction pressure of the compressor 12, becomes a two-phase gas-liquid refrigerant, and flows into the heat source heat exchanger 16. The low-pressure two-phase gas-liquid refrigerant that has flowed into the heat source heat exchanger 16 exchanges heat with the air around the heat source unit 10 that is supplied by the heat source fan 22, and evaporates, becoming a low-pressure gas refrigerant. The low-pressure gas refrigerant flows into the accumulator 20 via the flow path switching valve 14. The low-pressure gas refrigerant that has flowed into the accumulator 20 is again drawn into the compressor 12.

[0053] (2-5-3) Refrigerant Leakage Prevention Function When the refrigerant sensor 38 of any of the user units 30 detects a refrigerant leak, the control unit 70 fully closes the shutoff valve 52 of the shutoff valve unit 50 associated with the user unit 30 whose refrigerant sensor 38 has detected a refrigerant leak (hereinafter referred to as the leaking user unit). Furthermore, when the refrigerant sensor 38 of any of the user units 30 detects a refrigerant leak, the control unit 70 fully closes the user expansion valve 36 of the leaking user unit and the user expansion valves 36 of multiple user units 30 (hereinafter referred to as the user units of the leaking group) that are connected to the heat source unit 10 via the gas piping GP, together with the leaking user unit, via the shutoff valves 52 of the shutoff valve units 50 associated with the leaking user unit. 1, three utilization units 30 (all utilization units 30) are connected to the heat source unit 10 via the shutoff valve 52 of one shutoff valve unit 50, so the control unit 70 fully closes the utilization expansion valves 36 of all utilization units 30. This blocks the inflow of refrigerant from the heat source unit 10 to the leaking utilization unit and the utilization units of the leaking group through the connecting pipes 2, 4.

[0054] Note that the signal flow at this time may be such that the usage control unit 72 of the leaking usage unit reports the refrigerant leak to the heat source control unit 74 of the heat source unit 10, the heat source control unit 74 sends a command to close the usage expansion valve 36 to the usage control unit 72 of the usage unit in the leaking group, and then sends a command to close the shutoff valve 52 to the valve control unit 76 of the shutoff valve unit 50. However, with this type of signal flow, it may take some time for the shutoff valve 52 of the shutoff valve unit 50 and the usage expansion valve 36 of the usage unit in the leaking group to be closed.

[0055] Therefore, in this case, the utilization expansion valve 36 of the utilization unit of the leakage group is closed according to the signal flow shown in FIG.

[0056] First, when the refrigerant sensor 38 of the leaking utilization unit (referred to as utilization unit A in Figure 3) detects a refrigerant leak, it sends a signal notifying of the refrigerant leak to the utilization control unit 72 (an example of a controller in the claims) of the utilization unit A in which the refrigerant sensor 38 is installed.

[0057] In response to this, the usage control unit 72 of user unit A sends a command to close the shutoff valve 52 to the valve control unit 76 of the shutoff valve unit 50. The usage control unit 72 of user unit A also notifies the usage control units 72 of the user units in the leakage group (user units B and C in FIG. 3 ) that a refrigerant leak has occurred in user unit A. In other words, the usage control unit 72 of user unit A sends a command to close the usage expansion valve 36 to the usage control units 72 of user units B and C. Furthermore, the usage control unit 72 of user unit A fully closes the usage expansion valve 36 of user unit A. The usage control unit 72 of user unit A also stops operation of user unit A (stops operation of the usage fan 34).

[0058] The usage control units 72 of the usage units B and C, upon receiving the refrigerant leakage notification from the usage unit A (in other words, a command to close the usage expansion valve 36), fully close the usage expansion valves 36 of the usage units B and C. Furthermore, the usage control units 72 of the usage units B and C, upon receiving the refrigerant leakage notification from the usage unit A (in other words, a command to close the usage expansion valve 36), stop the operation of the usage fans 34 of the usage units B and C.

[0059] The usage control unit 72 of the usage unit A also notifies the heat source control unit 74 of the heat source unit 10 that a refrigerant leak has occurred in the usage unit A. For example, in the example of Fig. 1, if a refrigerant leak occurs in one usage unit 30, the operation of all usage units 30 will stop, and therefore the heat source control unit 74 of the heat source unit 10 will also stop the operation of the heat source unit 10.

[0060] (3) Features (3-1) An air conditioner 100, as an example of a refrigeration cycle apparatus, includes a heat source unit 10, a plurality of utilization units 30, a gas pipe GP, and a shutoff valve 52, as an example of a first shutoff valve. The heat source unit 10 has a compressor 12 and a heat source heat exchanger 16. Each of the plurality of utilization units 30 has a utilization heat exchanger 32. The gas pipe GP connects the compressor 12 of the heat source unit 10 to the utilization heat exchangers 32 of the plurality of utilization units 30. The gas pipe GP (including the communication pipe 4, the gas refrigerant pipe 28e, and the suction pipe 28a or the discharge pipe 28b) includes a first pipe 4a extending from the heat source unit 10, a second pipe 4b extending from the utilization unit 30, and a branch section 4c that branches the first pipe 4a into the plurality of second pipes 4b. The shutoff valve 52 is disposed in the gas pipe GP closer to the heat source unit 10 than the branch section 4c. Each utilization unit 30 has an adjustable opening utilization expansion valve 36 provided in the liquid piping LP (including the piping connecting the liquid end of the utilization heat exchanger 32 to the connecting piping 2, the connecting piping 2, and the liquid refrigerant piping 28d) connecting the utilization heat exchanger 32 of that utilization unit 30 to the heat source heat exchanger 16 of the heat source unit 10.

[0061] In the air conditioner 100, a shutoff valve 52 common to multiple utilization units is provided in the gas pipe GP, and an adjustable opening utilization expansion valve 36 (a shutoff valve that is also used as an expansion valve) is provided for each utilization unit 30. Therefore, the air conditioner 100 can respond to refrigerant leakage from the utilization unit 30 while reducing the number of parts.

[0062] (3-2) In the air conditioner 100, each utilization unit 30 has a refrigerant sensor 38. When the refrigerant sensor 38 of one utilization unit 30 detects a refrigerant leak, the shutoff valve 52 (of the shutoff valve unit 50) corresponding to the leaking utilization unit and the utilization expansion valves 36 of the multiple utilization units 30 connected to the heat source unit 10 via the shutoff valves 52 by the gas piping GP are closed.

[0063] With this air conditioner 100, it is possible to reduce the number of parts and prevent the concentration of leaking refrigerant from becoming high in the space where the utilization unit 30 is installed.

[0064] (3-3) In the air conditioner 100, the utilization units 30 have a utilization control unit 72 as an example of a controller. When the refrigerant sensor 38 of each utilization unit 30 detects a refrigerant leak, it sends a signal to the utilization control unit 72 of the utilization unit 30 in which the refrigerant sensor 38 is installed. The utilization control unit 72 of the utilization unit 30 in which the refrigerant sensor 38 that detected the refrigerant leak is installed (the leaking utilization unit) sends a command to close the utilization expansion valves 36 to the utilization control units 72 of the other utilization units 30 (the utilization units in the leaking group) that, together with the utilization unit 30 in which the leak was detected, are connected to the heat source unit 10 via the gas piping GP via the shut-off valves 52.

[0065] In the air conditioner 100, the utilization unit 30 receives a command to close the utilization expansion valve 36 from a utilization unit 30 located nearby without going through the heat source unit 10, so that the flow of refrigerant from the heat source unit 10 to the utilization unit 30 can be blocked early in the event of a refrigerant leak.

[0066] (3-4) In the air conditioner 100, when the utilization unit 30 receives a command to close the utilization expansion valve 36, it stops operating.

[0067] In this air conditioner 100, in addition to the leaking utilization unit, the operation of the utilization units 30 in the leaking group (especially the operation of the utilization fan 34) is stopped, which makes it easier to prevent the refrigerant flowing out from the utilization unit 30 from diffusing into the space in which the utilization unit 30 is installed.

[0068] (4) Modifications (4-1) Modification 1A In the above embodiment, all of the utilization units 30 share one shutoff valve unit 50, but the air conditioner 100 is not limited to this configuration.

[0069] For example, as shown in Fig. 4, the air conditioner 100 may include a plurality of shutoff valve units 50, and two or more of the plurality of utilization units 30 may share each shutoff valve unit 50. In the case of an embodiment such as that shown in Fig. 4, some of the plurality of shutoff valve units 50 may be dedicated to a single utilization unit 30.

[0070] 4, for example, the air conditioner 100 has a plurality of groups of utilization units 30 (first to Nth groups) each including a plurality of utilization units 30. One shutoff valve unit 50 is associated with the utilization units 30 in each group.

[0071] In this case, for example, suppose that one refrigerant sensor 38 of the first group of user units 30 detects a refrigerant leak. In this case, the shutoff valve 52 of the shutoff valve unit 50 corresponding to the first group of user units 30 is fully closed, and the user expansion valves 36 of all user units 30 in the first group are also fully closed.

[0072] At this time, if no refrigerant leakage is detected in the utilization units 30 of the second to Nth groups, the operation of the heat source unit 10 and the utilization units 30 of the second to Nth groups may be continued.

[0073] Second Embodiment An air conditioner 100A according to a second embodiment will be described with reference to the schematic configuration diagrams of FIGS. 5 and 6. FIG.

[0074] The main difference between the air conditioner 100A of the second embodiment and the air conditioner 100 of the first embodiment is that the air conditioner 100A includes multiple groups of utilization units 30, each of which includes multiple utilization units 30, and the utilization units 30 of each group can individually select cooling operation or heating operation, and has an intermediate unit 150 as an example of a shut-off valve unit.

[0075] The air conditioner 100A has many similarities to the air conditioner 100 of the first embodiment, so differences will be mainly described here, and commonalities will not be described unless specifically necessary.

[0076] (1) Overall Overview An air conditioner 100A, which is an example of a refrigeration cycle apparatus, mainly includes one heat source unit 110, a plurality of utilization units 30, a plurality of intermediate units 150 that switch the flow of refrigerant between the heat source unit 10 and the utilization units 30, and communication piping that connects the heat source unit 110, the intermediate units 150, and the utilization units 30. In the air conditioner 100A, one intermediate unit 150 is shared by the plurality of utilization units 30. The plurality of utilization units 30 that share the intermediate unit 150 are called a group of utilization units 30. In the example of FIG. 6 , the air conditioner 100A has two intermediate units 150, and the utilization units 30 include utilization units 30 of group A that share one intermediate unit 150 (150A) and utilization units 30 of group B that share the other intermediate unit 150 (150B).

[0077] In the air conditioner 100A, a refrigerant circuit 190 is configured by connecting the heat source unit 110, the intermediate unit 150, and the utilization units 30 via communication piping.

[0078] The communication pipes include a liquid communication pipe 102a, an intake gas communication pipe 102b, a high- and low-pressure gas communication pipe 102c, a first connection pipe 102d, a second connection pipe 102e, a third connection pipe 102f, and a communication pipe 104b.

[0079] (2) Detailed Configuration (2-1) Heat Source Unit The heat source unit 110 will be described with reference to Fig. 5. Fig. 5 is a refrigerant circuit diagram within the heat source unit 110 of the air conditioner 100A.

[0080] The heat source unit 110 is installed on the roof or in a machine room of the building in which the air conditioner 100 is installed. The heat source unit 110 mainly includes a first gas-side shut-off valve 119a, a second gas-side shut-off valve 119b, a liquid-side shut-off valve 119c, an accumulator 20, a compressor 12, a first flow path switching valve 14a, a second flow path switching valve 14b, a third flow path switching valve 14c, a heat-source heat exchanger 116, a first heat-source expansion valve 118a, and a second heat-source expansion valve 118b. These devices are connected via refrigerant piping to form a part of a refrigerant circuit 190. The heat source unit 110 also includes a heat-source fan 22 and a heat-source control unit 74.

[0081] The first gas-side shutoff valve 119a, the second gas-side shutoff valve 119b, and the liquid-side shutoff valve 119c are manually operated valves that are opened and closed during refrigerant charging, pumping down, etc. One end of the first gas-side shutoff valve 119a is connected to the suction gas communication pipe 102b, and the other end is connected to a refrigerant pipe extending to the accumulator 20. One end of the second gas-side shutoff valve 119b is connected to the high-low pressure gas communication pipe 102c, and the other end is connected to a refrigerant pipe extending to the second flow path switching valve 14b. One end of the liquid-side shutoff valve 119c is connected to the liquid communication pipe 102a, and the other end is connected to a refrigerant pipe extending to the first heat source expansion valve 118a or the second heat source expansion valve 118b.

[0082] The accumulator 20 is the same device as the accumulator 20 in the first embodiment. The accumulator 20 is disposed between the first gas-side shutoff valve 119a and the compressor 12.

[0083] The compressor 12 is the same as the compressor 12 in the first embodiment, and a detailed description of the compressor 12 will be omitted.

[0084] The first flow path switching valve 14a, the second flow path switching valve 14b, and the third flow path switching valve 14c (hereinafter collectively referred to as "flow path switching valve 14A") are four-way switching valves that switch the refrigerant flow depending on the situation (see the solid and dashed lines in FIG. 5). The refrigerant inlet of the flow path switching valve 14A is connected to a discharge pipe of the compressor 12 or a branch pipe extending from the discharge pipe. The flow path switching valve 14A is configured to block the flow of refrigerant in one refrigerant flow path, and effectively functions as a three-way valve. How the flow path switching valves 14a, 14b, and 14c control the refrigerant flow direction depending on the operation of the air conditioner 100A will be explained together with the explanation of the refrigerant flow in the air conditioner 100A.

[0085] The heat source heat exchanger 116 has a configuration similar to that of the heat source heat exchanger 16 of the first embodiment, but includes a first heat exchange section 116a and a second heat exchange section 116b. One end of the first heat exchange section 116a is connected to a refrigerant pipe connected to the third flow path switching valve 14c, and the other end is connected to a refrigerant pipe extending to the first heat source expansion valve 118a. One end of the second heat exchange section 116b is connected to a refrigerant pipe connected to the first flow path switching valve 14a, and the other end is connected to a refrigerant pipe extending to the second heat source expansion valve 118b. The refrigerant passing through the first heat exchange section 116a and the second heat exchange section 116b exchanges heat with the airflow generated by the heat source fan 22.

[0086] The first heat source expansion valve 118a and the second heat source expansion valve 118b are, for example, motor-operated valves with adjustable openings. One end of the first heat source expansion valve 118a is connected to a refrigerant pipe extending from the first heat exchanger 116a, and the other end is connected to a refrigerant pipe extending to the liquid-side shut-off valve 119c. One end of the second heat source expansion valve 118b is connected to a refrigerant pipe extending from the second heat exchanger 116b, and the other end is connected to a refrigerant pipe extending to the liquid-side shut-off valve 119c. The openings of the first heat source expansion valve 118a and the second heat source expansion valve 118b are adjusted according to the situation, and the pressure of the refrigerant passing through them is reduced according to the openings.

[0087] The heat source fan 22 is a device similar to the heat source fan 22 of the first embodiment, and generates an airflow that flows into the heat source unit 110 , passes through the heat source heat exchanger 116 , and flows out of the heat source unit 110 .

[0088] The heat source control unit 74 has the same configuration as the heat source control unit 74 in the first embodiment.

[0089] (2-2) Usage Unit The configuration of the usage unit 30 is the same as that of the usage unit in the first embodiment, and therefore a description thereof will be omitted.

[0090] (2-3) Intermediate Unit The communication pipe 104b, the second connection pipe 102e, the intake gas communication pipe 102b, and the pipe connecting the gas-side second shutoff valve 119b to the compressor 12, or the communication pipe 104b, the third connection pipe 102f, the high-low pressure gas communication pipe 102c, and the pipe connecting the gas-side first shutoff valve 119a to the compressor 12, constitute the gas pipe GP in the claims. The gas pipe GP connects the compressor 12 of the heat source unit 10 to the utilization heat exchangers 32 of the multiple utilization units 30. The gas pipe GP includes a first pipe (communication pipe 104b, second connection pipe 102e, third connection pipe 102f) extending from the heat source unit 10, a second pipe 104c extending from the utilization unit 30, and a branch section 104d that branches the first pipe into the multiple second pipes 104c. The connection pipe 104b is a portion of the connection pipe 4 that connects the heat source unit 10 and the branch portion 104d. The second pipe 104c is a portion of the connection pipe 4 that connects the utilization unit 30 and the branch portion 104d.

[0091] The intermediate unit 150 is an example of a shutoff valve unit. The intermediate unit 150 is disposed in the first pipe 4a of the connecting pipe 4. The shutoff valve unit 50 has expansion valves 152a, 152b as an example of a first shutoff valve disposed in the gas pipe GP closer to the heat source unit 10 than the branching portion 4c.

[0092] The intermediate unit 150 is disposed in the same location (such as above the ceiling) as the shutoff valve unit 50 of the first embodiment. Here, to avoid redundancy, a description of the installation position of the intermediate unit 150 will be omitted.

[0093] 6, the intermediate units 150 are arranged in the same number as the number of groups of utilization units 30 so as to correspond to the plurality of utilization units 30 (groups of utilization units 30). Note that some of the plurality of intermediate units 150 may be associated with a single utilization unit 30 rather than a plurality of utilization units 30. Each intermediate unit 150 is arranged between the corresponding group of utilization units 30 and the heat source unit 110, and switches the flow of refrigerant.

[0094] As shown in FIG. 6 , the intermediate unit 150 has two expansion valves 152 a and 152 b and a valve control unit 76 .

[0095] The expansion valves 152a and 152b are provided in the second connecting pipe 102e, the third connecting pipe 102f, and the interconnecting pipe 104b, and are mechanisms for adjusting the pressure and flow rate of the refrigerant. The expansion valves 152a and 152b are motor-operated valves (electronic expansion valves) that can adjust the opening degree. The expansion valves 152a and 152b are also used as shutoff valves in the event of a refrigerant leak, and are valves that have a small leakage amount when closed. For example, the expansion valves 152a and 152b have a leakage amount of 300 cm when closed. ３ / min (air, ΔP = 1.0 MPa) or less.

[0096] The expansion valves 152a, 152b switch between opening and closing the refrigerant flow path formed between the corresponding utilization unit and the heat source unit 110 depending on the situation. The operation of the expansion valves 152a, 152b will be explained later along with the operation of the air conditioner 100A. One end of the expansion valve 152a is connected to the communication pipe 104b that branches and extends to the gas ends of the multiple utilization heat exchangers 32, and the other end is connected to the second connection pipe 102e. The expansion valve 152b is connected to the communication pipe 104b that branches and extends to the gas ends of the multiple utilization heat exchangers 32, and the other end is connected to the third connection pipe 102f.

[0097] The valve control unit 76 is structurally similar to the valve control unit 76 of the first embodiment. The operation of the control unit 70 including the valve control unit 76 will be described later.

[0098] (2-4) Communication Piping One end of the liquid communication pipe 102a is connected to the liquid-side shutoff valve 119c, and the other end is connected to multiple first connection pipes 102d. One end of the first connection pipe 102d is connected to the liquid communication pipe 102a, and the other end branches off and is connected to multiple utilization units 30 belonging to one group. One end of the intake gas communication pipe 102b is connected to the gas-side first shutoff valve 119a, and the other end is connected to second connection pipes 102e extending from each intermediate unit 150. One end of the high / low pressure gas communication pipe 102c is connected to the gas-side second shutoff valve 119b, and the other end is connected to third connection pipes 102f extending from each intermediate unit 150. Each second connection pipe 102e has one end connected to the intake gas communication pipe 102b, and the other end is connected to a pipe in which the expansion valve 152a of the intermediate unit 150 is located. One end of each third connection pipe 102f is connected to the high / low pressure gas connection pipe 102c, and the other end is connected to a pipe in which an expansion valve 152b of the intermediate unit 150 is disposed. Each connection pipe 104b is connected to a pipe where the pipe in which the expansion valve 152a is disposed and the pipe in which the expansion valve 152b is disposed join together in the intermediate unit 150. One end of each connection pipe 104b branches at a branching portion 104d, flows through multiple second pipes 104c, and is connected to multiple utilization units 30.

[0099] (2-5) Control Unit The control unit 70 is made up of a usage control unit 72, a heat source control unit 74, and a valve control unit 76. The control unit 70 controls the overall operation of the air conditioner 100A by causing the control and arithmetic devices of the usage control unit 72, the heat source control unit 74, and the valve control unit 76 to execute programs stored in their respective storage devices.

[0100] FIG. 7 is a control block diagram of the air conditioner 100A in this embodiment.

[0101] 7 , the control unit 70 is electrically connected to the utilization expansion valves 36, utilization fans 34, and refrigerant sensors 38 of each of the utilization units 30, the compressor 12, flow path switching valve 14A, heat source expansion valves 118a, 118b, and heat source fan 22 of the heat source unit 10, and the expansion valves 152a, 152b of each of the intermediate units 150. The control unit 70 is also electrically connected to various sensors that measure the temperature and pressure of the refrigerant, the temperature of the air in the air-conditioned space, the outside air temperature, etc. The control unit 70 controls the operation of the various devices of the air conditioner 100A based on control signals received by the utilization units 30 from an operation remote control (not shown), measurement signals from the various sensors, etc.

[0102] (3) Refrigerant Flow During Operation of Air Conditioner The refrigerant flow during operation of the air conditioner 100A will be described for each situation, taking as an example the case where the user unit 30A of group A and the user unit 30B of group B in FIG. 6 are in operation.

[0103] (3-1) When both the utilization units 30A and 30B are performing cooling operation When both the multiple utilization units 30A and the multiple utilization units 30B are performing cooling operation, in the intermediate unit 150A corresponding to the multiple utilization units 30A and the intermediate unit 150B corresponding to the multiple utilization units 30B, the expansion valve 152a is fully opened and the expansion valve 152b is set to the minimum opening degree. Furthermore, the opening degree of each utilization expansion valve 36 of the multiple utilization units 30A and the multiple utilization units 30B is adjusted appropriately, and the first heat source expansion valve 118a and the second heat source expansion valve 118b are fully opened.

[0104] The flow of refrigerant in the refrigerant circuit 190 will be described. When the compressor 12 starts operating, refrigerant is drawn into the compressor 12 through the suction pipe and compressed. The compressed high-pressure gas refrigerant passes through the discharge pipe, the first flow path switching valve 14a, the third flow path switching valve 14c, etc., and flows into the heat source heat exchanger 116 where it condenses. The refrigerant that has passed through the heat source heat exchanger 116 passes through the liquid-side stop valve 119c and flows into the liquid communication pipe 102a. The refrigerant that has passed through the liquid communication pipe 102a reaches the first connection pipe 102d and flows into the multiple user units 30A and the multiple user units 30B.

[0105] The refrigerant that has reached the plurality of user units 30A or the plurality of user units 30B flows into the user expansion valve 36 and is decompressed. The decompressed refrigerant flows into each user heat exchanger 32 and evaporates. The refrigerant that has passed through each user heat exchanger 32 flows through the connection pipe 104b into the pipe in which the expansion valves 152a of the intermediate units 150A, 150B are disposed, and reaches the second connection pipe 102e. The refrigerant that has reached the second connection pipe 102e flows through the suction gas connection pipe 102b into the heat source unit 110 and is sucked into the compressor 12 again.

[0106] (3-2) When both the utilization units 30A and 30B are performing heating operation When both the multiple utilization units 30A and the multiple utilization units 30B are performing heating operation, in the intermediate units 150A and 150B, the expansion valves 152a are set to the minimum opening degree and the expansion valves 152b are set to the fully open degree. Also, the utilization expansion valves 36 of the multiple utilization units 30A and the multiple utilization units 30B are set to the fully open degree, and the opening degrees of the first heat source expansion valve 118a and the second heat source expansion valve 118b are adjusted appropriately.

[0107] The flow of refrigerant in the refrigerant circuit 190 will be described. When the compressor 12 starts operating, refrigerant is drawn into the compressor 12 through the suction pipe and compressed. The compressed high-pressure gas refrigerant passes through the discharge pipe, the second flow path switching valve 14b, etc., and flows into the high- and low-pressure gas communication pipe 102c. The refrigerant that has passed through the high- and low-pressure gas communication pipe 102c reaches the third connection pipe 102f. The refrigerant that has reached the third connection pipe 102f flows into the pipe in which the expansion valve 152b of the intermediate unit 150A or 150B is located, and then passes through the communication pipe 104b to reach the plurality of user units 30A or the plurality of user units 30B.

[0108] The refrigerant that has reached the plurality of utilization units 30A or the plurality of utilization units 30B flows into each utilization heat exchanger 32 and condenses. The refrigerant that has passed through each utilization heat exchanger 32 flows into the first connection pipe 102d. The refrigerant that has reached the first connection pipe 102d reaches the heat source unit 110 via the liquid connection pipe 102a.

[0109] The refrigerant that reaches the heat source unit 110 passes through the first heat source expansion valve 118a or the second heat source expansion valve 118b and is decompressed depending on the opening degree. The decompressed refrigerant flows into the heat source heat exchanger 116 and evaporates. The refrigerant that has passed through the heat source heat exchanger 116 passes through the first flow path switching valve 14a or the third flow path switching valve 14c and is sucked back into the compressor 12.

[0110] (3-3) When one of the utilization units 30A and 30B performs cooling operation and the other performs heating operation For example, when multiple utilization units 30A perform cooling operation and multiple utilization units 30B perform heating operation, in the intermediate unit 150A, the expansion valve 152a is fully opened and the expansion valve 152b is at its minimum opening. Furthermore, the openings of the utilization expansion valves 36 of the multiple utilization units 30A are adjusted appropriately. In the intermediate unit 150B, the expansion valve 152a is at its minimum opening and the expansion valve 152b is fully opened. Furthermore, the utilization expansion valves 36 of the multiple utilization units 30B are fully opened. Furthermore, the openings of the first heat source expansion valve 118a and the second heat source expansion valve 118b are adjusted appropriately.

[0111] The flow of refrigerant in the refrigerant circuit 190 will be described. When the compressor 12 is operating, refrigerant is drawn into the compressor 12 through the suction pipe and compressed. The high-pressure gas refrigerant compressed by the compressor 12 flows into the high-low pressure gas communication pipe 102c via the discharge pipe and the second flow path switching valve 14b. The refrigerant that has passed through the high-low pressure gas communication pipe 102c reaches the third connection pipe 102f. The refrigerant that has passed through the third connection pipe 102f flows into the intermediate unit 150B, flows through the pipe in which the expansion valve 152b is disposed, and flows into the communication pipe 104b.

[0112] The refrigerant that has passed through the communication pipe 104b reaches the plurality of user units 30B, and condenses in the user heat exchanger 32. The condensed refrigerant passes through the first connection pipe 102d, flows into the first connection pipe 102d that is connected to the plurality of user units 30A, and reaches the plurality of user units 30A.

[0113] The refrigerant that has reached the multiple utilization units 30A flows into the utilization expansion valve 36 of each utilization unit A and is decompressed according to the opening degree. The decompressed refrigerant flows into the utilization heat exchanger 32 and evaporates. The evaporated refrigerant passes through the connection pipe 104b, reaches the intermediate unit 150A, flows into the pipe in which the expansion valve 152a is arranged, and reaches the second connection pipe 102e.

[0114] The refrigerant that has reached the second connection pipe 102e passes through the intake gas communication pipe 102b, flows into the heat source unit 110, and is sucked into the compressor 12 again.

[0115] (3-4) Refrigerant Leakage Prevention Function When the refrigerant sensor 38 of any of the user units 30 detects a refrigerant leak, the control unit 70 fully closes the expansion valves 152a, 152b of the intermediate unit 150 associated with the user unit 30 whose refrigerant sensor 38 has detected a refrigerant leak (hereinafter referred to as the leaking user unit). Furthermore, when the refrigerant sensor 38 of any of the user units 30 detects a refrigerant leak, the control unit 70 fully closes the user expansion valve 36 of the leaking user unit and the user expansion valves 36 of multiple user units 30 (hereinafter referred to as the user units of the leaking group) that are connected to the heat source unit 10 via the gas piping GP, together with the leaking user unit, via the shutoff valves 52 of the shutoff valve units 50 associated with the leaking user unit.

[0116] 6, when a refrigerant leak is detected in one of the user units 30A in group A, the two user units 30A belonging to group A are connected to the heat source unit 10 via the expansion valves 152a and 152b of one intermediate unit 150A, so the control unit 70 fully closes the user expansion valves 36 of the two user units 30A. This blocks the inflow of refrigerant from the heat source unit 110 through the connecting pipe to the leaking user unit and the user units of the leaking group (to the user unit 30A in group A).

[0117] In the second embodiment, the utilization expansion valve 36 of the utilization unit 30 is also closed according to the signal flow shown in FIG.

[0118] First, when the refrigerant sensor 38 of the leaking utilization unit belonging to group A (referred to as utilization unit A in FIG. 8 ) detects a refrigerant leak, it sends a signal informing of the refrigerant leak to the utilization control unit 72 (an example of a controller in the claims) of utilization unit A in which the refrigerant sensor is installed.

[0119] In response to this, the usage control unit 72 of user unit A transmits a command to close the expansion valves 152a, 152b to the valve control unit 76 of the intermediate unit 150A. Furthermore, the usage control unit 72 of user unit A notifies the usage control units 72 of user units other than user unit A that belong to group A (in FIG. 8, usage units B and C) that a refrigerant leak has occurred in user unit A. In other words, the usage control unit 72 of user unit A transmits a command to close the usage expansion valve 36 to the usage control units 72 of user units B and C. Furthermore, the usage control unit 72 of user unit A fully closes the usage expansion valve 36 of user unit A. Furthermore, the usage control unit 72 of user unit A stops operation of user unit A (stops operation of the usage fan 34).

[0120] The usage control units 72 of the usage units B and C, upon receiving the refrigerant leakage notification from the usage unit A (in other words, a command to close the usage expansion valve 36), fully close the usage expansion valves 36 of the usage units B and C. Furthermore, the usage control units 72 of the usage units B and C, upon receiving the refrigerant leakage notification from the usage unit A (in other words, a command to close the usage expansion valve 36), stop the operation of the usage fans 34 of the usage units B and C.

[0121] The usage control unit 72 of the usage unit A also notifies the heat source control unit 74 of the heat source unit 10 that a refrigerant leak has occurred in the usage unit A.

[0122] Here, the user unit 30B of group B can continue to operate even if refrigerant is leaking from user unit A. However, if all user units 30A of group A stop, the amount of circulating refrigerant and other factors will change, so the heat source control unit 74 of the heat source unit 10 adjusts the rotation speed of the compressor 12 and the opening of the heat source expansion valves 118a, 118b and other factors.

[0123] In addition, if a refrigerant leak is detected in any of the usage units 30, the control unit 70 may stop operation of the compressor 12 and may also stop cooling / heating operation in all usage units other than the one in which the refrigerant leak is detected.

[0124] (4) Features (4-1) An air conditioner 100A as an example of a refrigeration cycle apparatus includes a heat source unit 110, a plurality of utilization units 30, a gas pipe GP, and expansion valves 152a, 152b as an example of first shutoff valves. The heat source unit 110 has a compressor 12 and a heat source heat exchanger 116. Each of the plurality of utilization units 30 has a utilization heat exchanger 32. The gas pipe GP connects the compressor 12 of the heat source unit 110 to the utilization heat exchangers 32 of the plurality of utilization units 30. The gas pipe GP includes a first pipe (communication pipe 104b, second connection pipe 102e, third connection pipe 102f) extending from the heat source unit 110, a second pipe 104c extending from the utilization unit 30, and a branching section 104d that branches the first pipe into the plurality of second pipes 104c. The expansion valves 152a, 152b are arranged in the gas piping GP closer to the heat source unit 110 than the branching point 104d. Each utilization unit 30 has an adjustable opening utilization expansion valve 36 provided in a liquid piping that connects the utilization heat exchanger 32 of that utilization unit 30 and the heat source heat exchanger 116 of the heat source unit 110.

[0125] In the air conditioner 100A, expansion valves 152a and 152b are provided in the gas pipe GP as first shutoff valves common to multiple utilization units 30, and an adjustable opening utilization expansion valve 36 (a shutoff valve that is also used as an expansion valve) is provided for each utilization unit 30. Therefore, the air conditioner 100A can respond to refrigerant leakage from the utilization units 30 while reducing the number of parts.

[0126] (4-2) In the air conditioner 100A, the expansion valves 152a and 152b are flow control valves whose opening degrees are adjustable.

[0127] In the air conditioner 100A, the expansion valves 152a and 152b serving as the first shutoff valves can be used not only as shutoff valves but also for flow rate adjustment purposes, making it possible to reduce the number of parts.

[0128] (4-3) In the air conditioner 100A, each utilization unit 30 has a refrigerant sensor 38. When the refrigerant sensor 38 of one utilization unit 30 detects a refrigerant leak, the expansion valves 152 a, 152 b (of the intermediate unit 150) corresponding to the leaking utilization unit and the utilization expansion valves 36 of the utilization units 30 connected to the heat source unit 110 via the gas piping GP via these expansion valves 152 a, 152 b are closed.

[0129] In this air conditioner 100A, it is possible to reduce the number of parts and prevent the concentration of leaking refrigerant from becoming high in the space where the utilization unit 30 is installed.

[0130] (4-4) In the air conditioner 100A, the utilization units 30 have a utilization control unit 72 as an example of a controller. When the refrigerant sensor of each utilization unit 30 detects a refrigerant leak, it sends a signal to the utilization control unit 72 of the utilization unit 30 in which the refrigerant sensor is installed. The utilization control unit 72 of the utilization unit 30 in which the refrigerant sensor 38 that detected the refrigerant leak is installed sends a command to close the utilization expansion valve 36 to the utilization control units 72 of the other utilization units 30 that, together with the utilization unit 30 in which the leak was detected, are connected to the heat source unit 110 via the gas piping GP via the expansion valves 152a, 152b.

[0131] In the air conditioner 100A, the utilization unit 30 receives a command to close the utilization expansion valve 36 from a utilization unit 30 located nearby without going through the heat source unit 110, so that the flow of refrigerant from the heat source unit 110 to the utilization unit 30 can be blocked early in the event of a refrigerant leak.

[0132] (4-5) In the air conditioner 100A, when the utilization unit 30 receives a command to close the utilization expansion valve 36, it stops operating.

[0133] In this air conditioner 100A, the operation (particularly the operation of the utilization fan 34) of the utilization unit 30 (which shares the same shut-off valve unit 50 as the leaking utilization unit) of the group to which the leaking utilization unit belongs is stopped, which makes it easier to prevent the refrigerant flowing out of the utilization unit 30 from diffusing into the space in which the utilization unit 30 is installed.

[0134] (5) Modifications (5-1) Modification 2A The air conditioner 100 of the first embodiment is equipped with a shutoff valve unit 50 having a shutoff valve 52 and a casing 54 that houses the shutoff valve 52, and the air conditioner 100A of the second embodiment is equipped with an intermediate unit 150 having expansion valves 152a, 152b and a casing 154 that houses the expansion valves 152a, 152b. However, it is not essential that the shutoff valve 52 and the expansion valves 152a, 152b be unitized as in the first and second embodiments. The shutoff valve 52 and the expansion valves 152a, 152b may be attached directly to the connecting pipes.

[0135] <Others> Although the embodiments of the present disclosure have been described above, it will be understood that various changes in form and details are possible without departing from the spirit and scope of the present disclosure as defined in the claims.

[0136] 4a First pipe 4b Second pipe 4c Branching section 10, 110 Heat source unit 12 Compressor 16, 116 Heat source heat exchanger 30 Usage unit 32 Usage heat exchanger 36 Usage expansion valve (second shutoff valve) 38 Refrigerant sensor 52 Shutoff valve (first shutoff valve) 72 Usage control section (controller) 100, 100A Air conditioner (refrigeration cycle device) 102e Second connecting pipe (first pipe) 102f Third connecting pipe (first pipe) 104b Communication pipe (first pipe) 104c Second pipe 104d Branching section 152a, 152b Expansion valve (first shutoff valve) GP Gas pipe LP Liquid pipe

[0137] Patent No. 6927315

Claims

1. A heat source unit (10, 110) having a compressor (12) and a heat source heat exchanger (16, 116); a plurality of utilization units (30) each having a utilization heat exchanger (32); a gas pipe (GP) including a first pipe (4a, 104b, 102e, 102f) extending from the heat source unit, a second pipe (4b, 104c) extending from the utilization unit, and a branching section (4c, 104d) for branching the first pipe into a plurality of second pipes, connecting the compressor of the heat source unit and the utilization heat exchangers of the plurality of utilization units; and a first shutoff valve (52, 152a, 152b) disposed in the gas pipe closer to the heat source unit than the branching section; each of the utilization units has a second shutoff valve (36) whose opening degree is adjustable and which is provided in a liquid pipe (LP) connecting the utilization heat exchanger of the utilization unit and the heat source heat exchanger of the heat source unit; 2. The refrigeration cycle apparatus (100A) according to claim 1, wherein the first shutoff valves (152a, 152b) are flow rate control valves whose opening degree is adjustable.

3. A refrigeration cycle device as described in claim 1 or 2, wherein each of the utilization units further has a refrigerant sensor (38), and when the refrigerant sensor of one of the utilization units detects a refrigerant leak, the first shut-off valve and the second shut-off valves of the plurality of utilization units connected to the heat source unit via the first shut-off valve by the gas piping are closed.

4. The refrigeration cycle apparatus of claim 3, further comprising a controller (72), wherein the refrigerant sensor of each of the utilization units, when detecting a refrigerant leak, transmits a signal to the controller of the utilization unit in which the refrigerant sensor is provided, and the controller of the utilization unit in which the refrigerant sensor that detected the refrigerant leak is provided transmits a command to close the second shutoff valve to the controllers of other utilization units that are connected to the heat source unit via the first shutoff valve by the gas piping together with the utilization unit in which the leak was detected.

5. The refrigeration cycle apparatus according to claim 4, wherein the utilization unit stops operation when it receives a command to close the second shutoff valve.

Images