REFRIGERATION CYCLE DEVICE

Abstract

The invention relates to a refrigeration cycle performing device capable of minimizing the deterioration of comfort in the target air-conditioned space even when a refrigerant leak in the user-side unit is detected and the inflow of refrigerant into the user-side unit is interrupted. The refrigeration cycle performing device (100) comprises a first heat source unit (2), several user-side units (1), a flow path switching unit (3), and a controller (8). The controller (8) controls the first heat source unit (2), the user-side units (1), and the flow path switching unit (3).When a refrigerant leak is detected in any of the several user-side units (1) in the air conditioning operation and the total capacity of the user-side units (1) except the user-side unit (1) in which the refrigerant leak was detected is equal to or greater than the predetermined ratio R of the capacity of the first heat source unit (2), the controller (8) performs the first control which includes the steps: causing the flow path switch (3) to interrupt the inflow of refrigerant into the user-side unit (1) in which the refrigerant leak was detected and to resume the operation of the user-side units (1) except the user-side unit (1) in which the refrigerant leak was detected.

Description

Refrigeration Cycle Equipment

[0001] This relates to a refrigeration cycle device.

[0002] Patent Document 1 (WO 2016 / 129027) discloses an air conditioning apparatus having a plurality of shutoff devices that are installed between a plurality of heat source units and indoor units, respectively, and that shut off the flow of refrigerant circulating through refrigerant piping, a plurality of leakage detection units that detect refrigerant leakage from each of the heat source units, and a control device that controls the operation of the plurality of heat source units, indoor units, and shutoff devices.

[0003] When a refrigerant leak is detected by the leak detection unit, the control device of the air conditioner activates the shutoff device connected to the heat source unit from which the refrigerant is leaking. If multiple shutoff devices include some that are activated and others that are deactivated, the control device calculates the limited heat exchange capacity of the indoor unit when operating with the heat source unit connected to the deactivated shutoff device, and controls the operation of the heat source unit or indoor unit with the limited heat exchange capacity as the upper limit. This allows the air conditioner of Patent Document 1 to minimize any deterioration in comfort in the air-conditioned space even when a refrigerant leak is shut off.

[0004] When a refrigerant leak is detected in a user unit (indoor unit) and the flow of refrigerant to the leaking user unit is cut off, there is room for consideration as to how to determine whether to continue operating other user units.

[0005] The present disclosure aims to provide a refrigeration cycle device that can minimize the deterioration of comfort in the air-conditioned space even when a refrigerant leak in a utilization unit is detected and the flow of refrigerant into the utilization unit is blocked.

[0006] A refrigeration cycle apparatus according to a first aspect performs air conditioning operation and includes a first heat source unit, a plurality of utilization units, a flow path switching unit, and a control unit.

[0007] The flow path switching unit is provided between the first heat source unit and the utilization unit, and switches the flow of refrigerant flowing between the first heat source unit and the utilization unit. The control unit controls the first heat source unit, the utilization unit, and the flow path switching unit.

[0008] The control unit performs a first control in which, when a refrigerant leak is detected in one of the multiple user units during air conditioning operation and the total capacity of the user units excluding the user unit in which the refrigerant leak was detected is equal to or greater than a predetermined percentage of the capacity of the first heat source unit, the flow path switching unit blocks the flow of refrigerant into the user unit in which the refrigerant leak was detected and continues operation of the user units excluding the user unit in which the refrigerant leak was detected.

[0009] According to the present refrigeration cycle apparatus, even if the inflow of refrigerant to a utilization unit where a refrigerant leak has occurred is blocked, the remaining utilization units can continue to operate. Therefore, even if a refrigerant leak in a utilization unit is detected and the inflow of refrigerant to the utilization unit is blocked, the present refrigeration cycle apparatus can minimize the deterioration of comfort in the air-conditioned space.

[0010] A second aspect of the refrigeration cycle device is a first aspect of the refrigeration cycle device, in which the control unit performs a second control in which, when a refrigerant leak is detected in any of a plurality of user units during air conditioning operation and the total capacity of the user units 1 excluding the user unit in which the refrigerant leak is detected is less than the above-mentioned predetermined percentage of the capacity of the first heat source unit, the flow path switching unit blocks the flow of refrigerant into the user unit in which the refrigerant leak is detected and the operation of all user units including the user unit in which the refrigerant leak is detected is stopped.

[0011] As a result, the present refrigeration cycle device suppresses a decrease in comfort caused by an inability to maintain operation at a desired capacity.

[0012] A refrigeration cycle apparatus according to a third aspect is the refrigeration cycle apparatus according to the first or second aspect, wherein the air-conditioning operation includes a defrosting operation, and the predetermined ratio is a ratio of the capacity of the utilization unit to the capacity of the first heat source unit, at which the first heat source unit can secure the amount of heat required for the refrigeration cycle apparatus to perform the defrosting operation.

[0013] The present refrigeration cycle apparatus can perform the defrosting operation while suppressing a deterioration in the comfort of the air-conditioned space when the inflow of refrigerant into the utilization unit is blocked.

[0014] A fourth aspect of the refrigeration cycle device is a third aspect of the refrigeration cycle device, and when the control unit determines that there are no plans to perform defrost operation, the first control is performed even if a refrigerant leak is detected in one of the multiple user units during air conditioning operation and the total capacity of the user units excluding the user unit in which the refrigerant leak is detected is less than the above-mentioned specified percentage of the capacity of the first heat source unit.

[0015] The refrigeration cycle device continues to operate the remaining utilization units, thereby minimizing the deterioration of comfort in the air-conditioned space even if a refrigerant leak in a utilization unit is detected and the flow of refrigerant to the utilization unit is blocked.

[0016] A fifth aspect of the present invention is a refrigeration cycle apparatus according to any one of the first to fourth aspects, wherein the utilization units have utilization heat exchangers, and the control unit, in the first control, adjusts the target evaporation temperature Te or the target condensation temperature Tc of the utilization heat exchanger of the utilization unit that continues to operate, based on the capacity of the utilization unit to which the inflow of refrigerant has been blocked.

[0017] This refrigeration cycle device allows the user units that continue to operate to block the inflow of refrigerant and compensate for the reduced output of the user units that have stopped operating, thereby minimizing the deterioration in comfort in the air-conditioned space.

[0018] A refrigeration cycle device of a sixth aspect is a refrigeration cycle device of any one of the first aspect to the fifth aspect, in which the control unit performs protection control based on the capacity of the utilization unit to which the inflow of refrigerant is blocked in the first control.

[0019] The present refrigeration cycle apparatus can suppress damage to the equipment caused by the execution of the first control.

[0020] A seventh aspect of the present invention is a refrigeration cycle apparatus according to any one of the first to sixth aspects, further comprising a second heat source unit. The flow path switching unit is provided between the second heat source unit and the plurality of utilization units, and further switches the flow of refrigerant flowing between the second heat source unit and the plurality of utilization units.

[0021] When performing the first control, the control unit causes the second heat source unit to perform an operation to compensate for the capacity of the utilization unit to which the inflow of refrigerant has been blocked.

[0022] In the first control, the refrigeration cycle device compensates for the decrease in output of the utilization unit that has stopped operating due to the second heat source unit blocking the inflow of refrigerant, thereby minimizing the deterioration in comfort in the air-conditioned space.

[0023] It is a schematic configuration diagram of the refrigeration cycle apparatus 100. It is a block diagram of a control unit 8. It is a flowchart showing a control flow of the refrigerant leakage control. It is a flowchart showing a control flow of the refrigerant leakage control performed by the refrigeration cycle apparatus 100 according to Modification A. It is a schematic configuration diagram of the refrigeration cycle apparatus 100 according to Modification D.

[0024] <Embodiment> (1) Overall Configuration The refrigeration cycle apparatus 100 performs air conditioning operations (specifically, full cooling operation, full heating operation, defrost operation, and simultaneous cooling and heating operation) in a space to be air-conditioned by using a vapor compression refrigeration cycle. The space to be air-conditioned is, for example, a space inside a building such as an office building, a commercial facility, or a residence. Note that the refrigeration cycle apparatus is merely one example of a refrigerant cycle apparatus, and the heat exchanger of the present disclosure may also be used in other refrigerant cycle apparatuses, such as a refrigerator, a freezer, a water heater, or a floor heating apparatus.

[0025] 1 , the refrigeration cycle apparatus 100 mainly has three utilization units 1, one heat source unit 2, three flow path switching units 3, one liquid refrigerant connection pipe 5, one low-pressure gas refrigerant connection pipe 6, one high-pressure gas refrigerant connection pipe 7, and one control unit 8. Note that the number of utilization units 1 and flow path switching units 3 is not limited to three, and may be two, or four or more.

[0026] The liquid refrigerant connection pipe 5, the low-pressure gas refrigerant connection pipe 6, and the high-pressure gas refrigerant connection pipe 7 are refrigerant connection pipes that connect the utilization units 1 and the heat source units 2. In the refrigeration cycle apparatus 100, the utilization units 1 and the heat source units 2 are connected via the liquid refrigerant connection pipe 5, the low-pressure gas refrigerant connection pipe 6, and the high-pressure gas refrigerant connection pipe 7 to form a refrigerant circuit 9.

[0027] In addition to air conditioning operation, the refrigeration cycle device 100 also performs refrigerant leakage control when a refrigerant leakage is detected in any of the multiple utilization units 1, with the aim of suppressing further refrigerant leakage while minimizing deterioration in the comfort of the air-conditioned space.

[0028] (2) Detailed Configuration (2-1) User Unit 1 Each user unit 1 mainly includes a user heat exchanger 11, a user fan 12, a user expansion mechanism 13, a liquid refrigerant pipe 14, a gas refrigerant pipe 15, and a refrigerant sensor 16.

[0029] In the following, when it is necessary to distinguish between the three user units 1 and the equipment possessed by each user unit 1, one of the suffixes a, b, or c will be added to the end of the reference numerals of the user unit 1 and the equipment possessed by each user unit 1, as shown in Figure 1.

[0030] (2-1-1) Utilization Heat Exchanger 11 The utilization heat exchanger 11 exchanges heat between the refrigerant and air carried by the airflow generated by the utilization fan 12. The utilization heat exchanger 11 has a liquid side connected to the liquid refrigerant communication pipe 5 via a liquid refrigerant pipe 14, and a gas side connected to the flow path switching unit 3 via a gas refrigerant pipe 15.

[0031] (2-1-2) Utilization Fan 12 The utilization fan 12 supplies air to the utilization heat exchanger 11 .

[0032] (2-1-3) Utilization Expansion Mechanism 13 The utilization expansion mechanism 13 adjusts the pressure and flow rate of the refrigerant flowing through the liquid refrigerant pipe 14. The utilization expansion mechanism 13 is provided in the liquid refrigerant pipe 14.

[0033] (2-1-4) Refrigerant Sensor 16 The refrigerant sensor 16 is provided at the installation location of the utilization unit 1 and detects the refrigerant. In other words, the refrigerant sensor 16 detects refrigerant leakage in the space to be air-conditioned.

[0034] (2-2) Heat Source Unit 2 The heat source unit 2 mainly includes a compressor 21, a first three-way valve 22, a second three-way valve 23, a heat source heat exchanger 24, a heat source expansion mechanism 25, and a heat source fan 26.

[0035] (2-2-1) Compressor 21 The compressor 21 draws low-pressure refrigerant in the refrigeration cycle from the refrigerant circuit 9 via the suction port 21a, compresses the refrigerant using a compression mechanism (not shown), and discharges the refrigerant into the refrigerant circuit 9 via the discharge port 21b.

[0036] The suction section 21a of the compressor 21 is connected to the low-pressure gas refrigerant communication pipe 6, and the discharge section 21b is connected to a first port 22a of the first three-way valve 22 and a first port 23a of the second three-way valve 23 (both described later).

[0037] (2-2-2) First Three-Way Valve 22 and Second Three-Way Valve 23 The first three-way valve 22 has three ports: a first port 22a, a second port 22b, and a third port 22c. The first port 22a of the first three-way valve 22 is connected to the discharge portion 21b of the compressor 21, the second port 22b is connected to the gas side of the heat source heat exchanger 24, and the third port 22c is connected to the suction portion 21a of the compressor 21.

[0038] The second three-way valve 23 has three ports: a first port 23 a, a second port 23 b, and a third port 23 c. The first port 23 a of the second three-way valve 23 is connected to the discharge portion 21 b of the compressor 21, the second port 23 b is connected to the high-pressure gas refrigerant communication pipe 7, and the third port 23 c is connected to the low-pressure gas refrigerant communication pipe 6 and the suction portion 21 a of the compressor 21.

[0039] The first three-way valve 22 and the second three-way valve 23 are changeable between a state in which the first ports 22a, 23a are connected to the second ports 22b, 23b while the third ports 22c, 23c are closed, and a state in which the second ports 22b, 23b are connected to the third ports 22c, 23c while the first ports 22a, 23a are closed.

[0040] (2-2-3) Heat Source Heat Exchanger 24 The heat source heat exchanger 24 exchanges heat between the refrigerant flowing inside and the heat source (for example, the air in the location where the heat source unit 2 is installed).

[0041] The heat source heat exchanger 24 has a gas side connected to the second port 22 b of the first three-way valve 22 , and a liquid side connected to the liquid refrigerant communication pipe 5 via a heat source expansion mechanism 25 .

[0042] (2-2-4) Heat Source Expansion Mechanism 25 The heat source expansion mechanism 25 adjusts the pressure and flow rate of the refrigerant flowing inside. The heat source expansion mechanism 25 is provided in the piping that connects the liquid side of the heat source heat exchanger 24 and the liquid refrigerant communication pipe 5.

[0043] (2-2-5) Heat Source Fan 26 The heat source fan 26 supplies external air, which is a heat source, to the heat source heat exchanger 24 .

[0044] (2-3) Flow path switching unit 3 The flow path switching unit 3 is provided between the heat source unit 2 and each utilization unit 1, and switches the flow of refrigerant flowing between the first heat source unit and the utilization unit 1. The flow path switching unit 3 has a first branch pipe 31, a second branch pipe 32, a first shut-off valve 33, and a second shut-off valve 34.

[0045] In the following, when it is necessary to distinguish between the three flow path switching units 3, one of the subscripts a, b, or c attached to the corresponding utilization unit 1 will be written at the end of the flow path switching unit 3 and the equipment that the flow path switching unit 3 has, as shown in Figure 1.

[0046] (2-3-1) First Branch Pipe 31 and Second Branch Pipe 32 The first branch pipe 31 is a pipe that connects the gas refrigerant pipe 15 of the utilization unit 1 to the low-pressure gas refrigerant communication pipe 6. The second branch pipe 32 is a pipe that connects the gas refrigerant pipe 15 of the utilization unit 1 to the high-pressure gas refrigerant communication pipe 7.

[0047] (2-3-2) First Shut-Off Valve 33 and Second Shut-Off Valve 34 The first shut-off valve 33 is a solenoid valve that can be opened and closed and is provided in the first branch pipe 31. The second shut-off valve 34 is a solenoid valve that can be opened and closed and is provided in the second branch pipe 32.

[0048] Closing the first shutoff valve 33 blocks the flow of refrigerant through the first branch pipe 31. Closing the second shutoff valve 34 blocks the flow of refrigerant through the second branch pipe 32.

[0049] (2-4) Control Unit 8 The control unit 8 controls the operations of various devices that make up the refrigeration cycle apparatus 100 .

[0050] 2 , the control unit 8 is electrically connected to the utilization fan 12, the utilization expansion mechanism 13, the refrigerant sensor 16, the compressor 21, the first three-way valve 22, the second three-way valve 23, the heat source expansion mechanism 25, the heat source fan 26, the first shut-off valve 33, and the second shut-off valve 34 so as to be able to send and receive signals. The control unit 8 may be electrically connected to various sensors (not shown) provided in the utilization unit 1 and the heat source unit 2. The control unit 8 may be able to communicate with a remote control (not shown) operated by a user of the refrigeration cycle apparatus 100.

[0051] The control unit 8 is realized by a computer. The control unit 8 includes a control and arithmetic unit and a storage device (both not shown). The control and arithmetic unit is a processor such as a CPU or GPU. The control and arithmetic unit reads a program stored in the storage device and performs predetermined image processing and arithmetic processing in accordance with the program. Furthermore, the control and arithmetic unit writes the results of calculations to the storage device and reads information stored in the storage device in accordance with the program.

[0052] The storage device stores the rated capacity of each utilization unit 1, the rated capacity of the first heat source unit 2, and a predetermined ratio R (described later).

[0053] (3) Operation of the refrigeration cycle apparatus 100 (3-1) Air-conditioning operation In air-conditioning operation, the control unit 8 of the refrigeration cycle apparatus 100 controls the various devices constituting the refrigeration cycle apparatus 100 as described below. Although detailed description will be omitted, the control unit 8 appropriately controls the rotation speeds of the utilization fan 12 and the heat source fan 26 during any operation.

[0054] (3-1-1) Full Cooling Operation Full cooling operation is an operation in which all utilization units 1 perform cooling operation.

[0055] In the full cooling operation, the first port 22a and the second port 22b of the first three-way valve 22 are in communication with each other. In each flow path switching unit 3, the first shutoff valve 33 is in an open state and the second shutoff valve 34 is in a closed state.

[0056] When all the second shutoff valves 34 are in the closed state, almost no refrigerant passes through the second three-way valve 23. Therefore, the state of the second three-way valve 23 is not limited.

[0057] When the compressor 21 starts, the refrigerant discharged from the compressor 21 passes through the first three-way valve 22 and then flows through the heat-source heat exchanger 24. In the heat-source heat exchanger 24, the refrigerant dissipates heat into the outdoor air and condenses. The refrigerant condensed in the heat-source heat exchanger 24 passes through the heat-source expansion mechanism 25, which is set to a fully open state, flows through the liquid refrigerant communication pipe 5, and is divided into each of the utilization units 1.

[0058] In all of the utilization units 1, the refrigerant is decompressed to a low pressure when passing through the utilization expansion mechanism 13 and flows through the utilization heat exchanger 11. In the utilization heat exchanger 11, the refrigerant absorbs heat from the air in the space to be air-conditioned and evaporates. As a result, the space to be air-conditioned corresponding to the utilization unit 1 is cooled. The opening degree of the utilization expansion mechanism 13 is adjusted according to the degree of superheat of the refrigerant determined by a temperature sensor (not shown) or the like.

[0059] The refrigerant flowing out of each utilization unit 1 flows through the first branch pipe 31 of each flow path switching unit 3, and joins together at the low-pressure gas refrigerant communication pipe 6. The refrigerant that joins together at the low-pressure gas refrigerant communication pipe 6 is drawn into the compressor 21 and compressed again.

[0060] (3-1-2) Full Heating Operation Full heating operation is an operation in which all utilization units 1 perform heating operation.

[0061] In the full heating operation, the second port 22b and the third port 22c of the first three-way valve 22 are connected, and the first port 23a and the second port 23b of the second three-way valve 23 are connected. In each flow path switching unit 3, the first shut-off valve 33 is closed and the second shut-off valve 34 is open.

[0062] When the compressor 21 starts up, the refrigerant discharged from the compressor 21 passes through the second three-way valve 23, flows through the high-pressure gas refrigerant communication pipe 7, and is branched into the second branch pipes 32 of each flow path switching unit 3. The refrigerant that has passed through each flow path switching unit 3 flows into each corresponding utilization unit 1.

[0063] In all of the utilization units 1, the refrigerant condenses by dissipating heat to the air in the space to be air-conditioned in the utilization heat exchanger 11. As a result, the space to be air-conditioned corresponding to the utilization unit 1 is heated. The refrigerant condensed in the utilization heat exchanger 11 passes through the utilization expansion mechanism 13. The opening degree of the utilization expansion mechanism 13 is adjusted according to the degree of subcooling of the refrigerant determined by a temperature sensor (not shown) or the like.

[0064] The refrigerants flowing out of each utilization unit 1 are joined in the liquid refrigerant communication pipe 5. The refrigerants joined in the liquid refrigerant communication pipe 5 are reduced in pressure to a low level when passing through the heat source expansion mechanism 25, and then flow through the heat source heat exchanger 24. In the heat source heat exchanger 24, the refrigerant absorbs heat from the outdoor air and evaporates. The refrigerant evaporated in the heat source heat exchanger 24 passes through the first three-way valve 22, then is drawn into the compressor 21 and compressed again.

[0065] (3-1-3) Defrost Operation The purpose of defrost operation is to remove frost that forms on the outer surface of the heat-source heat exchanger 24 when full heating operation is performed in an environment with low outdoor temperatures, such as in winter. In defrost operation, the control unit 8 performs a refrigeration cycle similar to full cooling operation while stopping the heat-source fan 26. As a result, the frost that forms on the outer surface of the heat-source heat exchanger 24 is removed by heat radiation from the refrigerant condensed in the heat-source heat exchanger 24. The operation of the various devices that make up the refrigeration cycle apparatus 100 in defrost operation is the same as in full cooling operation, except for the operation of the heat-source fan 26, and therefore detailed description thereof will be omitted.

[0066] (3-2) Simultaneous cooling and heating operation Simultaneous cooling and heating operation is an operation in which some of the utilization units 1 perform heating operation of the air-conditioned space, while the remaining utilization units 1 perform cooling operation of the air-conditioned space. The simultaneous cooling and heating operation includes a first simultaneous cooling and heating operation and a second simultaneous cooling and heating operation.

[0067] (3-2-1) First simultaneous cooling and heating operation The first simultaneous cooling and heating operation is a heating-dominated operation in which the number of utilization units 1 performing heating operation is greater than the number of utilization units 1 performing cooling operation. The following describes an example in which utilization units 1a and 1b perform heating operation and utilization unit 1c performs cooling operation.

[0068] In the first simultaneous cooling and heating operation, the first three-way valve 22 has the first port 22a and the second port 22b communicated with each other, and the second three-way valve 23 has the first port 23a and the second port 23b communicated with each other. In the flow path switching units 3a and 3b corresponding to the utilization units 1a and 1b, the first shut-off valve 33 is closed and the second shut-off valve 34 is open. In the flow path switching unit 3c corresponding to the utilization unit 1c, the first shut-off valve 33 is open and the second shut-off valve 34 is closed.

[0069] When the compressor 21 starts, the refrigerant discharged from the compressor 21 is divided into the first three-way valve 22 and the second three-way valve 23. The refrigerant that passes through the first three-way valve 22 condenses in the heat source heat exchanger 24, then passes through the heat source expansion mechanism 25, which is adjusted to a predetermined opening, and flows through the liquid refrigerant communication pipe 5. On the other hand, the refrigerant that passes through the second three-way valve 23 flows through the high-pressure gas refrigerant communication pipe 7 and into the second branch pipes 32 of the flow path switching units 3a, 3b corresponding to the utilization units 1a, 1b. The refrigerant that flows out of the second branch pipe 32 flows into the corresponding utilization unit 1.

[0070] In the utilization units 1a and 1b, the refrigerant condenses in the utilization heat exchanger 11 by dissipating heat to the air in the space to be air-conditioned. As a result, the space to be air-conditioned corresponding to the utilization units 1a and 1b is heated. The refrigerant condensed in the utilization heat exchanger 11 passes through the utilization expansion mechanism 13. Here, the opening degree of the utilization expansion mechanism 13 is adjusted according to the degree of subcooling of the refrigerant determined by a temperature sensor (not shown) or the like. The refrigerants that flow out of the utilization units 1a and 1b join together in the liquid refrigerant connection pipe 5.

[0071] The refrigerant that joins in the liquid refrigerant connection pipe 5 flows into the utilization unit 1c. The refrigerant that flows into the utilization unit 1c is reduced in pressure as it passes through the utilization expansion mechanism 13, and then flows through the utilization heat exchanger 11. In the utilization heat exchanger 11, the refrigerant absorbs heat from the air in the space to be air-conditioned and evaporates. As a result, the space to be air-conditioned corresponding to the utilization unit 1c is cooled. The refrigerant used to cool the space to be air-conditioned in the utilization unit 1c passes through the first branch pipe 31 of the flow path switching unit 3c corresponding to the utilization unit 1c, then flows through the low-pressure gas refrigerant connection pipe 6, and is drawn into the compressor 21 and compressed again.

[0072] (3-2-2) Second simultaneous cooling and heating operation The second simultaneous cooling and heating operation is a cooling-dominated operation in which the number of utilization units 1 performing heating operation is smaller than the number of utilization units 1 performing cooling operation. The following describes an example in which utilization unit 1a performs heating operation and utilization units 1b and 1c perform cooling operation.

[0073] In the second simultaneous cooling and heating operation, the first three-way valve 22 has the first port 22a and the second port 22b communicated with each other, and the second three-way valve 23 has the first port 23a and the second port 23b communicated with each other. In the flow path switching unit 3a corresponding to the user unit 1a performing the heating operation, the first shut-off valve 33 is closed and the second shut-off valve 34 is open. In the flow path switching units 3b and 3c corresponding to the user units 1b and 1c, the first shut-off valve 33 is open and the second shut-off valve 34 is closed.

[0074] When the compressor 21 starts, the refrigerant discharged from the compressor 21 is divided into the first three-way valve 22 and the second three-way valve 23. The refrigerant that passes through the first three-way valve 22 is condensed in the heat source heat exchanger 24, then passes through the heat source expansion mechanism 25, which is adjusted to a predetermined opening, and flows through the liquid refrigerant communication pipe 5. On the other hand, the refrigerant that passes through the second three-way valve 23 flows through the high-pressure gas refrigerant communication pipe 7 and into the second branch pipe 32 of the flow path switching unit 3a corresponding to the user unit 1a. The refrigerant that flows out of the second branch pipe 32 flows into the corresponding user unit 1.

[0075] In the utilization unit 1a, the refrigerant condenses in the utilization heat exchanger 11 by dissipating heat to the air in the space to be air-conditioned. As a result, the space to be air-conditioned corresponding to the utilization unit 1a is heated. The refrigerant condensed in the utilization heat exchanger 11 passes through the utilization expansion mechanism 13. Here, the opening degree of the utilization expansion mechanism 13 is adjusted according to the degree of subcooling of the refrigerant determined by a temperature sensor (not shown) or the like. The refrigerant that flows out of the utilization unit 1a flows into the liquid refrigerant connection pipe 5.

[0076] The refrigerant that flows into the liquid refrigerant communication pipe 5 is diverted to the utilization units 1b and 1c. This refrigerant is decompressed to a low pressure when passing through the utilization expansion mechanism 13, and then flows through the utilization heat exchanger 11. In the utilization heat exchanger 11, the refrigerant absorbs heat from the air in the space to be air-conditioned and evaporates. As a result, the space to be air-conditioned corresponding to the utilization units 1b and 1c is cooled. The refrigerant used to cool the space to be air-conditioned in the utilization units 1b and 1c passes through the first branch pipes 31 of the flow path switching units 3b and 3c, then meets in the low-pressure gas refrigerant communication pipe 6, is drawn into the compressor 21, and is compressed again.

[0077] (3-3) Control in the Event of Refrigerant Leakage In the control in the event of refrigerant leakage, the control unit 8 controls the various devices constituting the refrigeration cycle apparatus 100 as described below.

[0078] The control unit 8 performs the first control when, during air conditioning operation, a refrigerant leak is detected in any of the multiple usage units 1 (in other words, the refrigerant sensor 16 detects the refrigerant) and the total capacity (rated capacity) of the usage units 1 excluding the usage unit 1 in which the refrigerant leak is detected is equal to or greater than a predetermined percentage R of the capacity (rated capacity) of the first heat source unit 2.

[0079] In the first control, the control unit 8 blocks the flow of refrigerant into the utilization unit 1 in which a refrigerant leak has been detected using the flow path switching unit 3, and continues operation of the utilization units 1 except for the utilization unit 1 in which a refrigerant leak has been detected.

[0080] In addition, the control unit 8 performs the second control when, during air conditioning operation, a refrigerant leak is detected in any of the multiple usage units 1 (in other words, the refrigerant sensor 16 detects a refrigerant) and the total capacity of the usage units 1 excluding the usage unit 1 in which a refrigerant leak is detected is less than a predetermined percentage R of the capacity of the first heat source unit 2.

[0081] In the second control, the control unit 8 blocks the flow of refrigerant into the usage unit 1 in which a refrigerant leak has been detected using the flow path switching unit 3, and stops operation of all usage units 1, including the usage unit 1 in which a refrigerant leak has been detected.

[0082] The predetermined ratio R is the ratio of the capacity of the utilization unit 1 (the total capacity if there are multiple utilization units 1) to the capacity of the first heat source unit 2, at which the first heat source unit 2 can secure the amount of heat required for the refrigeration cycle apparatus 100 to perform the defrost operation. The amount of heat required for the refrigeration cycle apparatus 100 to perform the defrost operation is the amount of heat required for the heat source heat exchanger 24 to remove frost formed on the outer surface. In this embodiment, the predetermined ratio R is 50%.

[0083] The refrigerant leakage control will be specifically described with reference to the flowchart of Fig. 3. The refrigerant leakage control starts when the refrigeration cycle apparatus 100 is started.

[0084] In step S10, the control unit 8 determines whether a refrigerant leak has been detected in any of the multiple utilization units 1, specifically, whether a refrigerant has been detected by the refrigerant sensor 16. If the control unit 8 determines that a refrigerant has been detected (YES), the process proceeds to step S11. If the control unit 8 does not determine that a refrigerant has been detected (NO), the process proceeds to step S10.

[0085] In step S11, the control unit 8 calculates the total capacity Pa of the utilization units 1 excluding the utilization unit 1 in which the refrigerant was detected, and proceeds to step S12. Here, the total capacity Pa is a value calculated by adding up the rated capacities (units: horsepower, etc.) of the utilization units 1 excluding the utilization unit 1 in which the refrigerant was detected.

[0086] The control unit 8 calculates a total value Pa by adding up the rated capacities of the utilization units 1 excluding the utilization unit 1 in which the refrigerant has been detected.

[0087] In step S12, the control unit 8 determines whether the total value Pa is equal to or greater than a predetermined percentage R (50%) of the rated capacity Ps (units: horsepower, etc.) of the first heat source unit 2. If the total value Pa is equal to or greater than the predetermined percentage R of the rated capacity Ps of the first heat source unit 2 (Yes), the control unit 8 proceeds to step S13. If the total value Pa is not equal to or greater than the predetermined percentage R (50%) of the rated capacity Ps of the first heat source unit 2 (less than the predetermined percentage R) (No), the control unit 8 proceeds to step S14.

[0088] In step S13, the control unit 8 performs a first control to control when a refrigerant leak occurs. In the first control, the control unit 8 shuts off the inflow of refrigerant to the utilization unit 1 in which a refrigerant leak has been detected, using the flow path switching unit 3. Specifically, the control unit 8 closes the first shutoff valve 33 and the second shutoff valve 34 of the flow path switching unit 3 corresponding to the utilization unit 1 in which a refrigerant leak has been detected. At the same time, the control unit 8 continues operation of the utilization units 1 except for the utilization unit 1 in which a refrigerant leak has been detected.

[0089] For example, when the first control is performed in response to refrigerant detection by the refrigerant sensor 16 of the user unit 1a, the control unit 8 closes the first shutoff valve 33a and the second shutoff valve 34a of the flow path switching unit 3a. At this time, the control unit 8 stops the operation of the user unit 1a. At the same time, the control unit 8 continues the operation of the user units 1b and 1c.

[0090] In step S14, the control unit 8 performs the second control and ends the refrigerant leakage control. In the second control, the control unit 8 shuts off the flow of refrigerant into the utilization unit 1 in which the refrigerant leakage was detected using the flow path switching unit 3. At the same time, the control unit 8 stops the operation of all utilization units 1, including the utilization unit 1 in which the refrigerant leakage was detected.

[0091] For example, when the second control is performed in response to refrigerant detection by the refrigerant sensor 16 of the utilization unit 1a, the control unit 8 closes the first shutoff valve 33a and the second shutoff valve 34a of the flow path switching unit 3a. At the same time, the control unit 8 stops the operation of the utilization units 1a to 1c.

[0092] (4) Features (4-1) The refrigeration cycle apparatus 100 includes a first heat source unit 2, a plurality of utilization units 1, a flow path switching unit 3, and a control unit 8.

[0093] The flow path switching unit 3 is provided between the first heat source unit 2 and the utilization unit 1, and switches the flow of refrigerant flowing between the first heat source unit 2 and the utilization unit 1. The control unit 8 controls the first heat source unit 2, the utilization unit 1, and the flow path switching unit 3.

[0094] When a refrigerant leak is detected in any of the multiple user units 1 during air conditioning operation and the total capacity of the user units 1 excluding the user unit 1 in which the refrigerant leak was detected is equal to or greater than a predetermined percentage R of the capacity of the first heat source unit 2, the control unit 8 performs a first control in which the flow path switching unit 3 blocks the flow of refrigerant into the user unit 1 in which the refrigerant leak was detected and continues operation of the user units 1 excluding the user unit 1 in which the refrigerant leak was detected.

[0095] According to the refrigeration cycle apparatus 100, even if the inflow of refrigerant to a utilization unit 1 in which a refrigerant leak has occurred is blocked, it is possible to continue operation of the remaining utilization units 1. Therefore, even if a refrigerant leak in a utilization unit 1 is detected and the inflow of refrigerant to the utilization unit is blocked, the refrigeration cycle apparatus 100 can minimize the deterioration of comfort in the air-conditioned space.

[0096] (4-2) When a refrigerant leak is detected in any of the multiple user units 1 during air conditioning operation and the total capacity of the user units 1 excluding the user unit 1 in which the refrigerant leak is detected is less than a predetermined ratio R, the control unit 8 performs a second control in which the flow path switching unit 3 blocks the flow of refrigerant into the user unit 1 in which the refrigerant leak is detected and stops the operation of the user units excluding the user unit 1 in which the refrigerant leak is detected.

[0097] The refrigeration cycle apparatus 100 suppresses a decrease in comfort caused by an inability to maintain operation at a desired capacity.

[0098] (4-3) The air conditioning operation includes a defrost operation. The predetermined ratio R is a ratio of the capacity of the utilization unit 1 to the capacity of the first heat source unit 2, at which the first heat source unit 2 can secure the amount of heat required for the refrigeration cycle apparatus 100 to perform the defrost operation.

[0099] By blocking the flow of refrigerant into the utilization unit 1 in which a refrigerant leak is detected, the total amount of heat absorbed in the utilization unit 1 (specifically, the utilization heat exchanger 11) is reduced compared to when refrigerant flows into all of the utilization units 1. As a result, during defrost operation, the amount of heat dissipated in the heat source heat exchanger 24 may be insufficient to sufficiently remove frost (in other words, the refrigeration cycle apparatus 100 may not be able to perform the defrost operation).

[0100] In this embodiment, when the control unit 8 cuts off the inflow of refrigerant to the utilization unit 1 in which a refrigerant leak has been detected, the control unit 8 determines whether or not to continue operation of the utilization units 1 other than the utilization unit 1 in which a refrigerant leak has been detected, based on a predetermined ratio R. Therefore, even when the inflow of refrigerant to the utilization units 1 is cut off, the refrigeration cycle apparatus 100 performs defrost operation as long as the first heat source unit 2 can secure the required amount of heat.

[0101] Therefore, the refrigeration cycle apparatus 100 can perform the defrosting operation while suppressing a deterioration in the comfort of the air-conditioned space when the inflow of refrigerant into the utilization unit 1 is blocked.

[0102] (5) Modifications (5-1) Modification A When the air conditioning operation includes a defrosting operation, the control unit 8 may control the various devices constituting the refrigeration cycle apparatus 100 in the cooling leakage control as described below.

[0103] When the control unit 8 determines that there are no plans to perform defrost operation, it performs the first control even if a refrigerant leak is detected in one of the multiple usage units 1 during air conditioning operation and the total capacity of the usage units 1 excluding the usage unit 1 in which the refrigerant leak is detected is less than a predetermined percentage R of the capacity of the heat source unit 2.

[0104] The control performed by the refrigerant cycle apparatus 100 according to Modification A during refrigerant leakage will be specifically described with reference to the flowchart of Figure 4, focusing on the differences from the flowchart shown in Figure 3. In the following, the description of the steps that have already been described will be omitted.

[0105] The main difference between the flowchart shown in FIG. 3 and the flowchart shown in FIG. 4 is that the flowchart shown in FIG. 4 includes step S15.

[0106] In step S12, the control unit 8 determines whether the total value Pa is equal to or greater than a predetermined percentage R (50%) of the rated capacity Ps of the first heat source unit 2. If the total value Pa is equal to or greater than the predetermined percentage R of the rated capacity Ps of the first heat source unit 2 (Yes), the control unit 8 proceeds to step S13. If the total value Pa is not equal to or greater than the predetermined percentage R (50%) of the rated capacity Ps of the first heat source unit 2 (less than the predetermined percentage R) (No), the control unit 8 proceeds to step S15.

[0107] In step S15, the control unit 8 determines whether or not a defrost operation is scheduled to be performed in the refrigeration cycle apparatus 100. If the control unit 8 determines that a defrost operation is scheduled to be performed in the refrigeration cycle apparatus 100 (YES), the process proceeds to step S14. If the control unit 8 does not determine that a defrost operation is scheduled to be performed in the refrigeration cycle apparatus 100 (NO), the process proceeds to step S13.

[0108] The determination of whether or not the refrigeration cycle apparatus 100 is scheduled to perform a defrost operation is made, for example, based on a setting for whether or not to perform a defrost operation. The setting for whether or not to perform a defrost operation is set, for example, by a user. During relatively high temperatures, such as in summer, there is almost no possibility of frost formation, so the user may set the defrost operation as unnecessary. In such cases, the control unit 8 determines that the defrost operation is not scheduled to be performed. The setting for whether or not to perform a defrost operation may be made by the control unit 8 based on the detection results of a temperature sensor and / or a humidity sensor (not shown).

[0109] If a defrosting operation is not scheduled, even if the inflow of refrigerant to a utilization unit 1 in which a refrigerant leak has occurred is blocked, there is no need to consider ensuring the amount of heat required to perform the defrosting operation. Therefore, if a defrosting operation is not scheduled, the refrigeration cycle apparatus 100 according to Modification A continues operation of the remaining utilization units 1. The refrigeration cycle apparatus 100 according to Modification A can minimize the deterioration in comfort in the air-conditioned space even if a refrigerant leak in a utilization unit 1 is detected and the inflow of refrigerant to the utilization unit is blocked.

[0110] (5-2) Variation B In the first control, the control unit 8 may adjust the target evaporation temperature Te or the target condensation temperature Tc in the utilization heat exchanger 11 of the utilization unit 1 that continues to operate, based on the capacity of the utilization unit 1 to which the inflow of refrigerant has been blocked.

[0111] For example, the control unit 8 can reduce the target evaporation temperature Te in the utilization heat exchanger 11 of the utilization unit 1 that continues to operate based on the rated capacity of the utilization unit 1 that is stopped in the first control. Also, the control unit 8 can increase the target condensation temperature Tc in the utilization heat exchanger 11 of the utilization unit 1 that continues to operate based on the rated capacity of the utilization unit 1 that is stopped in the first control.

[0112] The refrigeration cycle device 100 according to variant B can minimize the deterioration in comfort in the air-conditioned space because the user unit 1 that continues to operate has had the inflow of refrigerant blocked and compensates for the decrease in output of the user unit 1 that has stopped operating.

[0113] (5-3) Modification C In the first control, the control unit 8 may perform protection control based on the capacity of the utilization unit 1 to which the inflow of refrigerant is blocked. The protection control is control to protect the devices constituting the refrigeration cycle apparatus 100 from a temporary increase in refrigerant pressure in the refrigerant circuit 9 caused by the inflow of refrigerant being blocked for some of the utilization units 1.

[0114] For example, during the first control, the control unit 8 can perform protective control by lowering the maximum rotation speed of the compressor 21 below the normal speed.

[0115] The refrigeration cycle apparatus 100 according to the modification C can suppress damage to the equipment caused by the execution of the first control.

[0116] (5-4) Modification D The refrigeration cycle apparatus 100 may further include a second heat source unit 2a, and when the first control is performed, the second heat source unit 2a may perform an operation to compensate for the capacity of the utilization unit 1 in which a refrigerant leak has been detected.

[0117] 5 , the refrigeration cycle apparatus 100 according to Modification D further includes a second heat source unit 2a. The flow path switching unit 3 is provided between the second heat source unit 2a and the plurality of utilization units 1, and further switches the flow of refrigerant flowing between the second heat source unit 2a and the plurality of utilization units 1. When performing the first control, the control unit 8 causes the second heat source unit 2a to operate to compensate for the capacity of the utilization unit 1 to which the inflow of refrigerant has been blocked.

[0118] Specifically, during the first control, the control unit 8 refers to the rated capacity of each utilization unit 1 recorded in the storage device and causes the second heat source unit 2a to operate to compensate for the rated capacity of the utilization unit 1 to which the inflow of refrigerant has been blocked.

[0119] In the refrigeration cycle device 100 according to variant D, in the first control, the second heat source unit 2a compensates for the decrease in output of the utilization unit that has stopped operating due to the inflow of refrigerant being blocked, thereby minimizing the deterioration in comfort of the air-conditioned space.

[0120] (5-5) Modification E The flow path switching unit 3 is not limited to an individual type that is installed at a separate position for each corresponding utilization unit 1. The flow path switching unit 3 may be an aggregate type in which the first branch pipe 31, the second branch pipe 32, the first shut-off valve 33, and the second shut-off valve 34 of a plurality of flow path switching units 3 are housed in a single casing.

[0121] (5-6) Modification F The predetermined ratio R may be a value other than 50%. Furthermore, the predetermined ratio R may be calculated based on a value other than the ratio of the total capacity of the utilization units 1 required for the refrigeration cycle apparatus 100 to the capacity of the first heat source unit 2.

[0122] <Conclusion> 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.

[0123] 1, 1a, 1b, 1c: utilization unit 2: first heat source unit 2a: second heat source unit 3, 3a, 3b, 3c: flow path switching unit 8: control unit 11, 11a, 11b, 11c: utilization heat exchanger 100: refrigeration cycle device Tc: target condensation temperature Te: target evaporation temperature R: predetermined ratio

[0124] International Publication No. 2016 / 129027

Claims

1. A refrigeration cycle apparatus (100) performing air conditioning operation, comprising: a first heat source unit (2); a plurality of utilization units (1, 1a, 1b, 1c); a flow path switching unit (3) provided between the first heat source unit and the utilization units for switching the flow of refrigerant flowing between the first heat source unit and the utilization units; and a control unit (8) for controlling the first heat source unit, the utilization units, and the flow path switching unit, wherein the control unit performs a first control in which, when a leakage of the refrigerant is detected in any of the plurality of utilization units during the air conditioning operation and the total capacity of the utilization units excluding the utilization unit in which the leakage of the refrigerant was detected is equal to or greater than a predetermined ratio (R) of the capacity of the first heat source unit, the control unit blocks the flow of the refrigerant to the utilization unit in which the leakage of the refrigerant was detected by the flow path switching unit, and continues operation of the utilization units excluding the utilization unit in which the leakage of the refrigerant was detected.

2. The refrigeration cycle apparatus of claim 1, wherein the control unit performs a second control in which, when a refrigerant leak is detected in any one of the plurality of utilization units during the air conditioning operation and the total capacity of the utilization units excluding the utilization unit in which the refrigerant leak is detected is less than the specified percentage of the capacity of the first heat source unit, the flow path switching unit blocks the flow of the refrigerant to the utilization unit in which the refrigerant leak is detected and stops operation of the utilization units excluding the utilization unit in which the refrigerant leak is detected.

3. A refrigeration cycle apparatus as described in claim 1 or 2, wherein the air conditioning operation includes a defrost operation, and the specified ratio is a ratio of the capacity of the utilization unit to the capacity of the first heat source unit at which the first heat source unit can secure the amount of heat required to perform the defrost operation.

4. The refrigeration cycle apparatus of claim 3, wherein when the control unit determines that there is no plan to perform the defrost operation, it performs the first control even if a refrigerant leak is detected in any of the multiple utilization units during the air conditioning operation and the total capacity of the utilization units excluding the utilization unit in which the refrigerant leak is detected is less than the specified percentage of the capacity of the first heat source unit.

5. A refrigeration cycle apparatus as described in any one of claims 1 to 4, wherein the utilization unit has a utilization heat exchanger (11, 11a, 11b, 11c), and the control unit, in the first control, adjusts the target evaporation temperature (Te) or the target condensation temperature (Tc) in the utilization heat exchanger of the utilization unit continuing operation based on the capacity of the utilization unit to which the inflow of the refrigerant has been blocked.

6. A refrigeration cycle device according to any one of claims 1 to 5, wherein the control unit performs protection control based on a capacity of the utilization unit to which the inflow of the refrigerant is blocked in the first control.

7. A refrigeration cycle device as described in any one of claims 1 to 6, further comprising a second heat source unit (2a), wherein the flow path switching unit is provided between the second heat source unit and a plurality of the utilization units and further switches the flow of the refrigerant flowing between the second heat source unit and the plurality of the utilization units, and the control unit, when performing the first control, causes the second heat source unit to perform an operation to compensate for the capacity of the utilization unit to which the inflow of the refrigerant has been blocked.

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