Air conditioner

Abstract

To provide an air conditioner capable of stopping supply of a refrigerant to a leakage part when the refrigerant leaks in an indoor heat exchanger.SOLUTION: An air conditioner 1 includes a refrigerant circuit 10 in which a compressor 21, gas-side refrigerant pipes 6 and 54, an outdoor heat exchanger 23, liquid-side refrigerant pipes 5 and 53, and an indoor heat exchanger 52 are connected and which performs a refrigeration cycle by circulating a refrigerant. The refrigerant circuit 10 includes the bypass circuit 61 that connects the gas-side bypass connection portion 65 of the gas-side refrigerant pipeline 6, 54 and the liquid-side bypass connection portion 66 of the liquid-side refrigerant pipeline 5, 53, the gas-side cutoff valve 58 provided between the indoor heat exchanger 52 and the gas-side bypass connection portion 65 in the gas-side refrigerant pipeline 6, 54, and the liquid-side cutoff valve 57 provided between the indoor heat exchanger 52 and the liquid-side bypass connection portion 66 in the liquid-side refrigerant pipeline 5, 53.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present disclosure relates to air conditioning devices. [Background technology]

[0002] Conventionally, there have been air conditioners that have a refrigerant circuit formed by connecting an outdoor unit having an outdoor heat exchanger and an indoor unit having an indoor heat exchanger, and in which the indoor unit is provided with bypass piping that allows the refrigerant to bypass the indoor heat exchanger.

[0003] For example, in a refrigeration cycle device described in Patent Document 1 (WO 2018 / 04249), a shutoff valve is provided on the liquid refrigerant side of the indoor heat exchanger to shut off the flow of refrigerant so that the supply of liquid refrigerant to the indoor heat exchanger can be stopped in the event of a refrigerant leak in the indoor heat exchanger. In this device, it is proposed that if the shutoff valve is closed and the refrigerant pressure increases, a high-pressure relief valve provided in the bypass piping is opened to release the refrigerant through the bypass piping. DISCLOSURE OF THE INVENTION [Problem to be solved by the invention]

[0004] In such a refrigeration cycle system, it is desirable to provide a shutoff valve on the gas refrigerant side of the indoor heat exchanger to prevent the refrigerant on the gas refrigerant side from being supplied to a leakage point in the indoor heat exchanger. In the event of a refrigerant leak, it is desirable to close the liquid-side shutoff valve and the gas-side shutoff valve to stop the refrigerant supply to the indoor heat exchanger. [Means for solving the problem]

[0005] An air conditioning apparatus according to a first aspect includes a refrigerant circuit. The refrigerant circuit connects a compressor, a gas side refrigerant pipe, an outdoor heat exchanger, a liquid side refrigerant pipe, and an indoor heat exchanger. The refrigerant circuit performs a refrigeration cycle by circulating refrigerant. The refrigerant circuit has a bypass circuit, a gas side shutoff valve, and a liquid side shutoff valve. The bypass circuit connects a gas side bypass connecting portion of the gas side refrigerant pipe and a liquid side bypass connecting portion of the liquid side refrigerant pipe. The gas side shutoff valve is provided in the gas side refrigerant pipe, between the indoor heat exchanger and the gas side bypass connecting portion. The liquid side shutoff valve is provided in the liquid side refrigerant pipe, between the indoor heat exchanger and the liquid side bypass connecting portion.

[0006] Because this air conditioning system is able to flow refrigerant through the bypass circuit, it is possible to reduce the refrigerant flow rate in the indoor heat exchanger compared to when refrigerant is not flowing through the bypass circuit, and it is possible to suppress the amount of heat exchanged by the refrigerant in the indoor heat exchanger. In this way, even in a refrigerant circuit that has a bypass circuit to suppress the amount of heat exchanged by the refrigerant in the indoor heat exchanger, if a refrigerant leak occurs in the indoor heat exchanger, it is possible to suppress the supply of refrigerant to the leaking location by closing the gas-side shutoff valve and the liquid-side shutoff valve.

[0007] An air conditioner according to a second aspect is the air conditioner according to the first aspect, wherein the gas-side shutoff valve has a leakage amount of 300 cm when the gas-side shutoff valve is closed and the differential pressure of the air before and after the gas-side shutoff valve is 1.0 MPa. 3 The liquid-side shutoff valve is a valve that leaks less than 300 cm when closed and the differential pressure between the front and rear of the valve is 1.0 MPa. 3 / min or less.

[0008] The leakage amount when the valve is closed is the leakage amount per valve.

[0009] This air conditioner can sufficiently reduce the amount of refrigerant leakage.

[0010] An air conditioner according to a third aspect is the air conditioner according to the first or second aspect, wherein the bypass circuit has a bypass valve. The bypass valve has a leakage amount of 300 cm when the bypass valve is closed and the differential pressure of the air before and after the bypass valve is 1.0 MPa. 3 / min more valves.

[0011] In this air conditioning system, even if refrigerant leaks through a closed bypass valve, the gas side shut-off valve and liquid side shut-off valve prevent the refrigerant from passing through, so the supply of refrigerant to the leaking point in the indoor heat exchanger is sufficiently suppressed.

[0012] An air conditioner according to a fourth aspect is the air conditioner of the third aspect, wherein the indoor heat exchanger includes a first indoor heat exchanger and a second indoor heat exchanger connected in parallel to each other in the refrigerant circuit. The gas side refrigerant piping includes a gas side main pipe, a gas side branch portion, a first gas side branch portion extending from the gas side branch portion toward the first indoor heat exchanger, and a second gas side branch portion extending from the gas side branch portion toward the second indoor heat exchanger. The liquid side refrigerant piping includes a liquid side main pipe, a liquid side branch portion, a first liquid side branch portion extending from the liquid side branch portion toward the first indoor heat exchanger, and a second liquid side branch portion extending from the liquid side branch portion toward the second indoor heat exchanger. The bypass circuit includes a first bypass circuit and a second bypass circuit. The first bypass circuit connects the first gas side bypass connection portion of the first gas side branch portion to the first liquid side bypass connection portion of the first liquid side branch portion and has a first bypass valve. The second bypass circuit connects the second gas side bypass connection portion of the second gas side branch portion to the second liquid side bypass connection portion of the second liquid side branch portion and has a second bypass valve. The gas side shutoff valves include a first gas side shutoff valve and a second gas side shutoff valve. The first gas side shutoff valve is provided in the first gas side branch portion between the indoor heat exchanger and the first gas side bypass connection portion. The second gas side shutoff valve is provided in the second gas side branch portion between the indoor heat exchanger and the second gas side bypass connection portion. The liquid side shutoff valves include a first liquid side shutoff valve and a second liquid side shutoff valve. The first liquid side shutoff valve is provided in the first liquid side branch portion between the indoor heat exchanger and the first liquid side bypass connection portion. The second liquid-side shutoff valve is provided in the second liquid-side branch portion between the indoor heat exchanger and the second liquid-side bypass connection portion.

[0013] This air conditioning apparatus can reduce the refrigerant flow rate in the first indoor heat exchanger by opening the first bypass valve and flowing the refrigerant through the first bypass circuit, thereby suppressing the amount of heat exchanged by the refrigerant in the first indoor heat exchanger, and / or can reduce the refrigerant flow rate in the second indoor heat exchanger by opening the second bypass valve and flowing the refrigerant through the second bypass circuit, thereby suppressing the amount of heat exchanged by the refrigerant in the second indoor heat exchanger.

[0014] An air conditioning apparatus according to a fifth aspect is an air conditioning apparatus according to the fourth aspect, in which, when refrigerant leaks in the flow path from the first gas side shut-off valve through the first indoor heat exchanger to the first liquid side shut-off valve, the first gas side shut-off valve and the first liquid side shut-off valve are closed, and when refrigerant leaks in the flow path from the second gas side shut-off valve through the second indoor heat exchanger to the second liquid side shut-off valve, the second gas side shut-off valve and the second liquid side shut-off valve are closed.

[0015] This air conditioner can keep the amount of refrigerant leakage to a minimum by closing the gas-side shutoff valve and liquid-side shutoff valve corresponding to the location where the refrigerant leakage has occurred.

[0016] An air conditioning apparatus according to a sixth aspect is the air conditioning apparatus according to the fifth aspect, and is capable of operating in two ways: increasing the opening of the first bypass valve to reduce the flow rate of refrigerant in the first indoor heat exchanger, and increasing the opening of the second bypass valve to reduce the flow rate of refrigerant in the second indoor heat exchanger.

[0017] This air conditioner is capable of performing an operation to reduce the amount of heat exchanged by the refrigerant in the first indoor heat exchanger, and an operation to reduce the amount of heat exchanged by the refrigerant in the second indoor heat exchanger.

[0018] An air conditioner according to a seventh aspect is the air conditioner according to any one of the first to sixth aspects, further comprising an indoor casing. The indoor casing houses an indoor heat exchanger and a gas-side shut-off valve therein.

[0019] This air conditioner can easily be configured with an indoor unit that can control the gas-side shutoff valve in the event of a leak.

[0020] An air conditioner according to an eighth aspect is the air conditioner according to the seventh aspect, wherein the liquid-side shutoff valve is housed inside the indoor casing.

[0021] In this air conditioning device, the gas-side shut-off valve and liquid-side shut-off valve are arranged together inside the indoor casing, making it easy to construct an indoor unit that can control the gas-side shut-off valve and liquid-side shut-off valve in the event of a leak.

[0022] An air conditioner according to a ninth aspect is the air conditioner according to the seventh or eighth aspect, further comprising a refrigerant leakage sensor. The refrigerant leakage sensor is provided inside the indoor casing.

[0023] This air conditioner is capable of detecting the presence of refrigerant leakage within the indoor casing.

[0024] An air conditioner according to a tenth aspect is the air conditioner according to any one of the first to ninth aspects, wherein the refrigerant includes R32.

[0025] This air conditioner can suppress leakage even when using R32, a flammable refrigerant. [Brief explanation of the drawings]

[0026] [Figure 1] 1 is a diagram showing a schematic configuration of an air conditioning apparatus according to one embodiment. [Figure 2] FIG. 2 is a diagram showing a refrigerant circuit of the air conditioning apparatus. [Figure 3] FIG. 2 is a control block diagram of the air conditioning apparatus. [Figure 4] FIG. 10 is a diagram showing a control flow when a refrigerant leaks. DETAILED DESCRIPTION OF THE INVENTION

[0027] An air conditioner 1 will be described below as an example of one embodiment of the air conditioner.

[0028] (1) Air conditioning system configuration The air conditioner 1 is a device that performs cooling and heating of spaces to be air-conditioned, such as rooms in a building, a kitchen, a data center, a computer room, etc., by performing a vapor compression refrigeration cycle.

[0029] As shown in Figures 1 and 2, the air conditioning device 1 mainly has an outdoor unit 2, multiple indoor units, namely a first indoor unit 3a and a second indoor unit 3b, a liquid refrigerant connection pipe 5, a gas refrigerant connection pipe 6, and a control unit 7.

[0030] The multiple indoor units, a first indoor unit 3a and a second indoor unit 3b, are connected in parallel to the outdoor unit 2. A liquid refrigerant connection pipe 5 and a gas refrigerant connection pipe 6 connect the outdoor unit 2 to the first indoor unit 3a and the second indoor unit 3b. A control unit 7 controls the components of the outdoor unit 2, the first indoor unit 3a, and the second indoor unit 3b.

[0031] The air conditioner 1 has a refrigerant circuit 10 configured by connecting an outdoor unit 2, a first indoor unit 3a, a second indoor unit 3b, a liquid refrigerant communication pipe 5, and a gas refrigerant communication pipe 6. The refrigerant circuit 10 is filled with R32 as a refrigerant.

[0032] The liquid refrigerant communication pipe 5 mainly has a liquid side main pipe section 5m extending from the outdoor unit 2 to the liquid side branch section 5x, a first liquid side branch pipe section 5a branching from the liquid side main pipe section 5m and extending to the first indoor unit 3a, and a second liquid side branch pipe section 5b branching from the liquid side main pipe section 5m and extending to the second indoor unit 3b.

[0033] The gas refrigerant communication pipe 6 mainly includes a gas side main pipe section 6m extending from the outdoor unit 2 to the gas side branch section 6x, a first gas side branch pipe section 6a branching from the gas side main pipe section 6m and extending to the first indoor unit 3a, and a second gas side branch pipe section 6b branching from the gas side main pipe section 6m and extending to the second indoor unit 3b.

[0034] (1-2) Indoor unit A first indoor unit 3a and a second indoor unit 3b, which are multiple indoor units, are installed in spaces to be air-conditioned, such as rooms in a building, a kitchen, a data center, a computer room, etc. In this embodiment, the first indoor unit 3a and the second indoor unit 3b are floor-standing indoor units installed on the floor of the spaces to be air-conditioned.

[0035] As described above, the first indoor unit 3a and the second indoor unit 3b are connected in parallel to the outdoor unit 2 via the liquid refrigerant communication pipe 5 and the gas refrigerant communication pipe 6, and form part of the refrigerant circuit 10.

[0036] The configurations of the first indoor unit 3a and the second indoor unit 3b will be described below.

[0037] The first indoor unit 3a and the second indoor unit 3b have the same configuration. The second indoor unit 3b has the same configuration as the first indoor unit 3a, except that "second" is added instead of "first" and the subscript "b" is added instead of the subscript "a".

[0038] (1-2-1) First indoor unit The first indoor unit 3a has a first indoor liquid refrigerant pipe 53a, a first indoor heat exchanger 52a, a first indoor gas refrigerant pipe 54a, a first bypass circuit 61a, a first indoor expansion valve 57a, a first gas side shut-off valve 58a, a first indoor fan 55a, a first indoor heat exchanger liquid side sensor 71a, a first indoor heat exchanger gas side sensor 72a, a first indoor air sensor 73a, a first refrigerant leakage sensor 74a, a first indoor control unit 59a, a first indoor casing 30a, and the like.

[0039] The first indoor casing 30a accommodates a first indoor liquid refrigerant pipe 53a, a first indoor heat exchanger 52a, a first indoor gas refrigerant pipe 54a, a first bypass circuit 61a, a first indoor expansion valve 57a, a first gas-side shutoff valve 58a, a first indoor fan 55a, a first indoor control unit 59a, a first indoor heat exchanger liquid-side sensor 71a, a first indoor heat exchanger gas-side sensor 72a, a first indoor air sensor 73a, and a first refrigerant leakage sensor 74a. The first indoor casing 30a is, for example, a housing whose longitudinal direction is vertical.

[0040] The first indoor liquid refrigerant pipe 53a connects the liquid side end of the first indoor heat exchanger 52a and the end of the first liquid side branch pipe portion 5a of the liquid refrigerant communication pipe 5.

[0041] The first indoor heat exchanger 52a is a heat exchanger that functions as a refrigerant evaporator to cool the indoor air, or functions as a refrigerant radiator to heat the indoor air.

[0042] The first indoor gas refrigerant pipe 54a connects the gas side end of the first indoor heat exchanger 52a and the end of the first gas side branch pipe portion 6a of the gas refrigerant communication pipe 6.

[0043] The first bypass circuit 61a connects a first liquid-side bypass connection portion 66a of the first indoor gas refrigerant pipe 54a and a first gas-side bypass connection portion 65a of the first indoor liquid refrigerant pipe 53a, while bypassing the first indoor heat exchanger 52a. The first bypass circuit 61a has a first pressure reduction portion 62a, a first on-off valve 63a, and a first check valve 64a. The first pressure reduction portion 62a, the first on-off valve 63a, and the first check valve 64a are arranged in this order in the flow direction from the first gas-side bypass connection portion 65a toward the first liquid-side bypass connection portion 66a.

[0044] The first pressure reducing section 62a has a portion where the refrigerant flow path is narrowed, and reduces the pressure of the refrigerant passing through it, and is formed of, for example, a capillary tube.

[0045] The first on-off valve 63a is a valve that can be switched between two states, an open state and a closed state, and in this embodiment is configured as a solenoid valve that only allows refrigerant to flow from the first gas side bypass connecting portion 65a side toward the first liquid side bypass connecting portion 66a (from the gas side toward the liquid side). When the valve is in the closed state and the differential pressure of the air before and after is 1.0 MPa, the leakage amount when the first on-off valve 63a is closed is greater than that of the first indoor expansion valve 57a and is greater than that of the first gas side shutoff valve 58a. Specifically, when the first on-off valve 63a is controlled to the closed state and the differential pressure of the air before and after is 1.0 MPa, the leakage amount when the first on-off valve 63a is closed is 300 cm 3 / min more than 500cm 3 / min. The leakage amount when the first on-off valve 63a is closed is also the leakage amount passing through the first on-off valve 63a from the first gas-side bypass connecting portion 65a side toward the first liquid-side bypass connecting portion 66a, and is also the leakage amount passing through the first on-off valve 63a from the first liquid-side bypass connecting portion 66a side toward the first gas-side bypass connecting portion 65a.

[0046] The first check valve 64a is configured as a valve that allows refrigerant to flow only from the first gas-side bypass connecting portion 65a side toward the first liquid-side bypass connecting portion 66a (from the gas side toward the liquid side). When the air pressure difference is 1.0 MPa, the leakage amount when the first check valve 64a is closed is greater than that of the first indoor expansion valve 57a and greater than that of the first gas-side shutoff valve 58a. Specifically, when the air pressure difference before and after the first check valve 64a is 1.0 MPa, the leakage amount when the first check valve 64a is closed, which is the amount of refrigerant leaking through the first check valve 64a from the first liquid-side bypass connecting portion 66a side toward the first gas-side bypass connecting portion 65a, is 300 cm 3 / min more than 500cm 3 / min. The leakage amount when the valve is closed can be, for example, the leakage amount when the valve temperature is 20°C (the same applies in this specification).

[0047] The first indoor expansion valve 57a is an expansion valve provided in the first indoor liquid refrigerant pipe 53a. More specifically, the first indoor expansion valve 57a is provided in the first indoor liquid refrigerant pipe 53a, between the first liquid-side bypass connection portion 66a and the first indoor heat exchanger 52a. The first indoor expansion valve 57a is an electric expansion valve that can adjust the flow rate of refrigerant flowing through the first indoor heat exchanger 52a while reducing the pressure of the refrigerant. The first indoor expansion valve 57a has a leakage rate of 300 cm when the valve is closed and the air pressure difference between before and after the valve is 1.0 MPa, which is less than that of the first on-off valve 63a. 3 / min or less, and is a valve with a flow rate of 200cm 3 / min or less.

[0048] The first gas-side shutoff valve 58a is an expansion valve provided in the first indoor gas refrigerant pipe 54a. More specifically, the first gas-side shutoff valve 58a is provided in the first indoor gas refrigerant pipe 54a, between the first gas-side bypass connection portion 65a and the first indoor heat exchanger 52a. The first gas-side shutoff valve 58a is controlled to close when a refrigerant leak is detected in the first indoor unit 3a, thereby suppressing the passage of refrigerant. The first gas-side shutoff valve 58a is, for example, an electric expansion valve. When the first gas-side shutoff valve 58a is in a closed state and the differential pressure of the air before and after the valve is set to 1.0 MPa, the leakage amount when the valve is closed is less than that of the first opening / closing valve 63a, and is 300 cm 3 / min or less, and is a valve with a flow rate of 200cm 3 / min or less.

[0049] The first indoor circuit 3aa of the first indoor unit 3a is composed of the first indoor liquid refrigerant pipe 53a, the first indoor expansion valve 57a, the first indoor heat exchanger 52a, the first indoor gas refrigerant pipe 54a, the first gas side shut-off valve 58a, and the first bypass circuit 61a.

[0050] The first indoor fan 55a supplies indoor air to the first indoor heat exchanger 52a as a cooling or heating source for the refrigerant flowing through the first indoor heat exchanger 52a. The first indoor fan 55a is driven by a first indoor fan motor 55am. In this embodiment, the first indoor fan motor 55am is in only two states: a driven state and a stopped state, and the rotation speed of the first indoor fan motor 55am cannot be controlled. For this reason, the first indoor fan 55a is a fan with a constant airflow rate.

[0051] The first indoor heat exchanger liquid-side sensor 71a detects the refrigerant temperature at the liquid-side end of the first indoor heat exchanger 52a. The first indoor heat exchanger gas-side sensor 72a detects the refrigerant temperature at the gas-side end of the first indoor heat exchanger 52a. The first indoor air sensor 73a detects the temperature of the indoor air drawn into the first indoor unit 3a before passing through the first indoor heat exchanger 52a. The first refrigerant leakage sensor 74a detects refrigerant leakage in the first indoor unit 3a. The first refrigerant leakage sensor 74a can be, for example, a semiconductor gas sensor or a sensor that detects a sudden drop in refrigerant pressure in the first indoor unit 3a.

[0052] The first indoor control unit 59a is connected to the second indoor control unit 59b and the outdoor control unit 20 (described later) so as to be able to communicate with them, and constitutes part of the control unit 7. The first indoor control unit 59a may be configured to include, for example, a processor such as a CPU (Central Processing Unit) and memories such as RAM (Random Access Memory) and ROM (Read Only Memory). The first indoor control unit 59a is connected to each sensor so as to acquire detection information from the first indoor heat exchanger liquid-side sensor 71a, the first indoor heat exchanger gas-side sensor 72a, the first indoor air sensor 73a, and the first refrigerant leakage sensor 74a. The first indoor control unit 59a is also capable of controlling the first indoor expansion valve 57a, the first gas-side shutoff valve 58a, the first indoor fan 55a, and the first on-off valve 63a. The first indoor control unit 59a has an input unit (not shown) that can receive the set temperature for the first indoor unit 3a.

[0053] (1-2-2) Second indoor unit The second indoor unit 3b has a second indoor liquid refrigerant pipe 53b, a second indoor heat exchanger 52b, a second indoor gas refrigerant pipe 54b, a second bypass circuit 61b, a second indoor expansion valve 57b, a second gas side shut-off valve 58b, a second indoor fan 55b, a second indoor heat exchanger liquid side sensor 71b, a second indoor heat exchanger gas side sensor 72b, a second indoor air sensor 73b, a second refrigerant leakage sensor 74b, a second indoor control unit 59b, a second indoor casing 30b, and the like.

[0054] The second indoor casing 30b accommodates a second indoor liquid refrigerant pipe 53b, a second indoor heat exchanger 52b, a second indoor gas refrigerant pipe 54b, a second bypass circuit 61b, a second indoor expansion valve 57b, a second gas-side shut-off valve 58b, a second indoor fan 55b, a second indoor control unit 59b, a second indoor heat exchanger liquid-side sensor 71b, a second indoor heat exchanger gas-side sensor 72b, a second indoor air sensor 73b, and a second refrigerant leakage sensor 74b. The second indoor casing 30b is, for example, a housing whose longitudinal direction is vertical.

[0055] The second indoor liquid refrigerant pipe 53b connects the liquid side end of the second indoor heat exchanger 52b and the end of the second liquid side branch pipe portion 5b of the liquid refrigerant communication pipe 5.

[0056] The second indoor heat exchanger 52b is a heat exchanger that functions as a refrigerant evaporator to cool the indoor air, or functions as a refrigerant radiator to heat the indoor air.

[0057] The second indoor gas refrigerant pipe 54b connects the gas side end of the second indoor heat exchanger 52b and the end of the second gas side branch pipe portion 6b of the gas refrigerant communication pipe 6.

[0058] The second bypass circuit 61b connects a second liquid-side bypass connection portion 66b of the second indoor gas refrigerant pipe 54b and a second gas-side bypass connection portion 65b of the second indoor liquid refrigerant pipe 53b, while bypassing the second indoor heat exchanger 52b. The second bypass circuit 61b has a second pressure reduction portion 62b, a second on-off valve 63b, and a second check valve 64b. The second pressure reduction portion 62b, the second on-off valve 63b, and the second check valve 64b are arranged in this order in the flow direction from the second gas-side bypass connection portion 65b toward the second liquid-side bypass connection portion 66b.

[0059] The second pressure reducing section 62b has a portion where the refrigerant flow path is narrowed, and reduces the pressure of the refrigerant passing through it, and is formed of, for example, a capillary tube.

[0060] The second on-off valve 63b is a valve that can be switched between two states, an open state and a closed state, and in this embodiment is configured as a solenoid valve that only allows refrigerant to flow from the second gas side bypass connecting portion 65b side toward the second liquid side bypass connecting portion 66b (from the gas side toward the liquid side). When the valve is in the closed state and the differential pressure of the air before and after is 1.0 MPb, the leakage amount when the second on-off valve 63b is closed is greater than that of the second indoor expansion valve 57b and is greater than that of the second gas side shutoff valve 58b. Specifically, when the second on-off valve 63b is controlled to the closed state and the differential pressure of the air before and after is 1.0 MPb, the leakage amount when the second on-off valve 63b is closed is 300 cm 3 / min more than 500cm 3 / min. The leakage amount when the second on-off valve 63b is closed is also the leakage amount passing through the second on-off valve 63b from the second gas side bypass connecting portion 65b side toward the second liquid side bypass connecting portion 66b, and is also the leakage amount passing through the second on-off valve 63b from the second liquid side bypass connecting portion 66b side toward the second gas side bypass connecting portion 65b.

[0061] The second check valve 64b is configured as a valve that allows refrigerant to flow only from the second gas-side bypass connecting portion 65b side toward the second liquid-side bypass connecting portion 66b (from the gas side toward the liquid side). When the air pressure difference is 1.0 MPb, the leakage amount when the second check valve 64b is closed is greater than that of the second indoor expansion valve 57b and greater than that of the second gas-side shutoff valve 58b. Specifically, when the air pressure difference before and after the second check valve 64b is 1.0 MPb, the leakage amount when the second check valve 64b is closed, which is the amount of refrigerant leaking through the second check valve 64b from the second liquid-side bypass connecting portion 66b side toward the second gas-side bypass connecting portion 65b, is 300 cm 3 / min more than 500cm 3 / min or more valves.

[0062] The second indoor expansion valve 57b is an expansion valve provided in the second indoor liquid refrigerant pipe 53b. More specifically, the second indoor expansion valve 57b is provided in the second indoor liquid refrigerant pipe 53b, between the second liquid-side bypass connection portion 66b and the second indoor heat exchanger 52b. The second indoor expansion valve 57b is an electric expansion valve that can adjust the flow rate of refrigerant flowing through the second indoor heat exchanger 52b while reducing the pressure of the refrigerant. The leakage amount of the second indoor expansion valve 57b when the valve is closed and the differential pressure of the air before and after it is 1.0 MPb is less than that of the second on-off valve 63b, being 300 cm 3 / min or less, and is a valve with a flow rate of 200cm 3 / min or less.

[0063] The second gas-side shutoff valve 58b is an expansion valve provided in the second indoor gas refrigerant pipe 54b. More specifically, the second gas-side shutoff valve 58b is provided in the second indoor gas refrigerant pipe 54b, between the second gas-side bypass connection portion 65b and the second indoor heat exchanger 52b. The second gas-side shutoff valve 58b is controlled to close when a refrigerant leak is detected in the second indoor unit 3b, thereby suppressing the passage of refrigerant. The second gas-side shutoff valve 58b is, for example, an electric expansion valve. When the second gas-side shutoff valve 58b is in a closed state and the differential pressure of the air before and after the valve is set to 1.0 MPb, the leakage amount when the second gas-side shutoff valve 58b is closed is less than that of the second opening / closing valve 63b, at 300 cm 3 / min or less, and is a valve with a flow rate of 200cm 3 / min or less.

[0064] The second indoor circuit 3bb of the second indoor unit 3b is composed of the second indoor liquid refrigerant pipe 53b, the second indoor expansion valve 57b, the second indoor heat exchanger 52b, the second indoor gas refrigerant pipe 54b, the second gas side shut-off valve 58b, and the second bypass circuit 61b.

[0065] The second indoor fan 55b supplies indoor air to the second indoor heat exchanger 52b as a cooling or heating source for the refrigerant flowing through the second indoor heat exchanger 52b. The second indoor fan 55b is driven by a second indoor fan motor 55bm. In this embodiment, the second indoor fan motor 55bm is in only two states: a driven state and a stopped state, and the rotation speed of the second indoor fan motor 55bm cannot be controlled. For this reason, the second indoor fan 55b is a fan with a constant airflow rate.

[0066] The second indoor heat exchanger liquid-side sensor 71b detects the refrigerant temperature at the liquid-side end of the second indoor heat exchanger 52b. The second indoor heat exchanger gas-side sensor 72b detects the refrigerant temperature at the gas-side end of the second indoor heat exchanger 52b. The second indoor air sensor 73b detects the temperature of the indoor air drawn into the second indoor unit 3b before passing through the second indoor heat exchanger 52b. The second refrigerant leakage sensor 74b detects refrigerant leakage in the second indoor unit 3b. The second refrigerant leakage sensor 74b can be, for example, a semiconductor gas sensor or a sensor that detects a sudden drop in refrigerant pressure in the second indoor unit 3b.

[0067] The second indoor control unit 59b is connected to the first indoor control unit 59a and the outdoor control unit 20 so as to be able to communicate with them, and constitutes part of the control unit 7. The second indoor control unit 59b may be configured, for example, to include a processor such as a CPU (Central Processing Unit) and memories such as RAM (Random Access Memory) and ROM (Read Only Memory). The second indoor control unit 59b is connected to each sensor so as to acquire detection information from the second indoor heat exchanger liquid-side sensor 71b, the second indoor heat exchanger gas-side sensor 72b, the second indoor air sensor 73b, and the second refrigerant leakage sensor 74b. The second indoor control unit 59b can also control the second indoor expansion valve 57b, the second gas-side shutoff valve 58b, the second indoor fan 55b, and the second on-off valve 63b. The second indoor control unit 59b has an input unit (not shown) that can receive the set temperature for the second indoor unit 3b.

[0068] (1-3) Outdoor unit The outdoor unit 2 is installed outdoors of a building or the like, for example, on the roof or ground. As described above, the outdoor unit 2 is connected to the first indoor unit 3a and the second indoor unit 3b via the liquid refrigerant connection pipe 5 and the gas refrigerant connection pipe 6, and constitutes part of the refrigerant circuit 10.

[0069] The outdoor unit 2 mainly includes a liquid-side shutoff valve 27, a second outdoor gas refrigerant pipe 35, a suction refrigerant pipe 31, a discharge refrigerant pipe 32, a first outdoor gas refrigerant pipe 33, an outdoor liquid refrigerant pipe 34, a compressor 21, a switching valve 22, an outdoor heat exchanger 23, an outdoor fan 24, an outdoor expansion valve 25, a subcooling circuit 41, a subcooling heat exchanger 45, a gas-side shutoff valve 28, an accumulator 29, a discharge pressure sensor 36, a discharge temperature sensor 37, a suction pressure sensor 39, an outdoor heat exchanger liquid-side sensor 38, and an outdoor control unit 20. These components that make up the outdoor unit 2 are housed in an outdoor casing (not shown).

[0070] The gas-side shutoff valve 28 is connected to the gas refrigerant communication pipe 6.

[0071] The second outdoor gas refrigerant pipe 35 connects the gas side shutoff valve 28 and a first port which is a connection port of the switching valve 22.

[0072] The suction refrigerant pipe 31 is a refrigerant pipe that forms a flow path from the second port, which is the connection port of the switching valve 22, to the suction side of the compressor 21. An accumulator 29 that temporarily accumulates the refrigerant that is suctioned into the compressor 21 is provided midway along the suction refrigerant pipe 31.

[0073] The discharge refrigerant pipe 32 connects the discharge side of the compressor 21 to a third port which is a connection port of the switching valve 22 .

[0074] The first outdoor gas refrigerant pipe 33 connects a fourth port, which is a connection port of the switching valve 22, to the gas side end of the outdoor heat exchanger .

[0075] The outdoor liquid refrigerant pipe 34 connects the liquid side end of the outdoor heat exchanger 23 and the liquid side shut-off valve 27 .

[0076] The liquid-side shut-off valve 27 is connected to the liquid refrigerant connection pipe 5. The liquid-side shut-off valve 27 and the gas-side shut-off valve 28 are valves that are opened and closed manually. During operation, the liquid-side shut-off valve 27 and the gas-side shut-off valve 28 are in an open state.

[0077] The compressor 21 is a device for compressing a refrigerant, and is, for example, a compressor of a sealed structure in which a volumetric compression element (not shown), such as a rotary type or a scroll type, is rotationally driven by a compressor motor 21a.

[0078] The switching valve 22 is a device capable of switching the flow of refrigerant in the refrigerant circuit 10, and is, for example, a four-way switching valve. When the outdoor heat exchanger 23 is made to function as a refrigerant radiator and the first indoor heat exchanger 52a and the second indoor heat exchanger 52b are made to function as refrigerant evaporators (cooling operation state), the switching valve 22 connects the discharge side of the compressor 21 to the gas side of the outdoor heat exchanger 23 (see the solid line of the switching valve 22 in FIG. 2). When the outdoor heat exchanger 23 is made to function as a refrigerant evaporator and the first indoor heat exchanger 52a and the second indoor heat exchanger 52b are made to function as refrigerant radiators (heating operation state), the switching valve 22 connects the suction side of the compressor 21 to the gas side of the outdoor heat exchanger 23 (see the dashed line of the switching valve 22 in FIG. 2).

[0079] The outdoor heat exchanger 23 is a heat exchanger that functions as a radiator of the refrigerant or as an evaporator of the refrigerant.

[0080] The outdoor fan 24 draws outdoor air into the outdoor unit 2, exchanges heat with the refrigerant in the outdoor heat exchanger 23, and then discharges the air to the outside. The outdoor fan 24 is driven by an outdoor fan motor.

[0081] The outdoor expansion valve 25 is an expansion valve provided in the outdoor liquid refrigerant pipe 34. The outdoor expansion valve 25 is an electric expansion valve that reduces the pressure of the refrigerant during heating operation, and is provided in a portion of the outdoor liquid refrigerant pipe 34 near the liquid side end of the outdoor heat exchanger 23.

[0082] The subcooling heat exchanger 45 is provided in the outdoor liquid refrigerant pipe 34, closer to the liquid-side shut-off valve 27 than the point where the subcooling circuit 41 extends from the outdoor liquid refrigerant pipe 34. The subcooling heat exchanger 45 exchanges heat between the refrigerant flowing through the outdoor liquid refrigerant pipe 34 and the refrigerant flowing through the subcooling circuit 41.

[0083] The subcooling circuit 41 branches off from the outdoor liquid refrigerant pipe 34 and is connected to the suction refrigerant pipe 31. The outdoor expansion valve 25 is located in a portion of the outdoor liquid refrigerant pipe 34 closer to the outdoor heat exchanger 23 than the portion where the subcooling circuit 41 is connected. The subcooling circuit 41 includes a refrigerant return inlet pipe 42 and a refrigerant return outlet pipe 43. The refrigerant return inlet pipe 42 sends the refrigerant branching from the outdoor liquid refrigerant pipe 34 to the subcooling heat exchanger 45. The refrigerant return inlet pipe 42 is provided with a subcooling expansion valve 44. The subcooling expansion valve 44 reduces the pressure of the refrigerant flowing through the subcooling circuit 41 while adjusting the flow rate of the refrigerant flowing through the subcooling heat exchanger 45. The subcooling expansion valve 44 is an electrically operated expansion valve. The refrigerant return outlet pipe 43 sends the refrigerant flowing through the outlet of the subcooling heat exchanger 45 to the suction refrigerant pipe 31. The subcooling heat exchanger 45 cools the refrigerant flowing through the outdoor liquid refrigerant pipe 34 by the refrigerant flowing through the subcooling circuit 41 .

[0084] The discharge pressure sensor 36 detects the pressure of the refrigerant discharged from the compressor 21. The discharge temperature sensor 37 detects the temperature of the refrigerant discharged from the compressor 21. The suction pressure sensor 39 detects the pressure of the refrigerant sucked into the compressor 21. The outdoor heat exchanger liquid-side sensor 38 detects the temperature of the refrigerant at the liquid-side end of the outdoor heat exchanger 23.

[0085] The outdoor control unit 20 is communicatively connected to the first indoor control unit 59a and the second indoor control unit 59b and constitutes part of the control unit 7. The outdoor control unit 20 may be configured to include, for example, a processor such as a CPU (Central Processing Unit) and memories such as RAM (Random Access Memory) and ROM (Read Only Memory). The outdoor control unit 20 is connected to each sensor so as to acquire detection information from the discharge pressure sensor 36, the discharge temperature sensor 37, the suction pressure sensor 39, and the outdoor heat exchanger liquid-side sensor 38. The outdoor control unit 20 can also control the drive frequency of the compressor 21, the connection state of the switching valve 22, the airflow rate of the outdoor fan 24, the valve opening degree of the outdoor expansion valve 25, and the valve opening degree of the subcooling expansion valve 44.

[0086] (1-4) Control unit The control unit 7 is configured by connecting the outdoor control unit 20, a first indoor control unit 59a, and a second indoor control unit 59b so that they can communicate with each other. The control unit 7 controls the operation of the air conditioner 1 as a whole.

[0087] (2) Basic operation of air conditioning equipment Next, we will explain the basic operation of the air conditioner 1. As mentioned above, the basic operation of the air conditioner 1 includes cooling operation and heating operation. The basic operation of the air conditioner 1 explained below is performed by the control unit 7, which controls the components of the air conditioner 1 (outdoor unit 2, first indoor unit 3a, second indoor unit 3b).

[0088] (2-1) Cooling operation When performing cooling operation, the control unit 7 switches the connection state of the switching valve 22 to the cooling operation state and drives the compressor 21, the outdoor fan 24, the first indoor fan 55a, and the second indoor fan 55b so that the first indoor heat exchanger 52a and the second indoor heat exchanger 52b all function as refrigerant evaporators and the outdoor heat exchanger 23 functions as a refrigerant radiator. The first gas-side shutoff valve 58a and the second gas-side shutoff valve 58b are fully open. The first on-off valve 63a and the second on-off valve 63b are fully closed, and no refrigerant flows through the first bypass circuit 61a or the second bypass circuit 61b.

[0089] The high-pressure refrigerant discharged from the compressor 21 is sent to the outdoor heat exchanger 23 through the switching valve 22. The refrigerant sent to the outdoor heat exchanger 23 is cooled and condensed by exchanging heat with outdoor air supplied by the outdoor fan 24 in the outdoor heat exchanger 23, which functions as a refrigerant radiator. This refrigerant flows out of the outdoor unit 2 through the outdoor expansion valve 25, the subcooling heat exchanger 45, and the liquid-side shut-off valve 27. At this time, in the subcooling heat exchanger 45, the refrigerant flowing out of the outdoor unit 2 is cooled by the refrigerant flowing through the subcooling circuit 41.

[0090] When the refrigerant flowing out from the outdoor unit 2 flows through the liquid refrigerant communication pipe 5, it branches off at the liquid side branch portion 5x to flow through the first liquid side branch pipe portion 5a and the second liquid side branch pipe portion 5b.

[0091] The refrigerant that flows through the first liquid-side branch pipe 5a flows into the first indoor unit 3a, where it is decompressed by the first indoor expansion valve 57a and then sent to the first indoor heat exchanger 52a. The valve opening of the first indoor expansion valve 57a is controlled to satisfy a predetermined condition, such as the degree of superheat of the refrigerant flowing through the gas side of the first indoor heat exchanger 52a being equal to or greater than a predetermined value. The degree of superheat may be calculated, for example, using the detected values ​​of the first indoor heat exchanger gas-side sensor 72a and the suction pressure sensor 39. The refrigerant sent to the first indoor heat exchanger 52a evaporates in the first indoor heat exchanger 52a, which functions as a refrigerant evaporator, by exchanging heat with indoor air supplied from the room by the first indoor fan 55a. The evaporated refrigerant flows out of the first indoor unit 3a. The indoor air cooled in the first indoor heat exchanger 52a is sent into the room to cool the room targeted by the first indoor unit 3a.

[0092] Meanwhile, the refrigerant that has flowed through the second liquid-side branch pipe 5b flows into the second indoor unit 3b, where it is decompressed by the second indoor expansion valve 57b and sent to the second indoor heat exchanger 52b. The valve opening of the second indoor expansion valve 57b is controlled to satisfy a predetermined condition, such as the degree of superheat of the refrigerant flowing through the gas side of the second indoor heat exchanger 52b being equal to or greater than a predetermined value. The degree of superheat may be calculated, for example, using the detected values ​​of the second indoor heat exchanger gas-side sensor 72b and the suction pressure sensor 39. The refrigerant sent to the second indoor heat exchanger 52b evaporates in the second indoor heat exchanger 52b, which functions as a refrigerant evaporator, by exchanging heat with indoor air supplied from the room by the second indoor fan 55b. The evaporated refrigerant flows out of the second indoor unit 3b. The indoor air cooled in the second indoor heat exchanger 52b is sent into the room, thereby cooling the room targeted by the second indoor unit 3b.

[0093] Thereafter, the refrigerant flowing out of the first indoor unit 3a and the refrigerant flowing out of the second indoor unit 3b join together in the gas refrigerant communication pipe 6 and are sent to the outdoor unit 2. The refrigerant sent to the outdoor unit 2 passes through the gas-side shut-off valve 28, the switching valve 22, and the accumulator 29, and is sucked into the compressor 21.

[0094] (2-2) Heating operation When performing heating operation, the control unit 7 switches the connection state of the switching valve 22 to the heating operation state and drives the compressor 21, the outdoor fan 24, the first indoor fan 55a, and the second indoor fan 55b so that the first indoor heat exchanger 52a and the second indoor heat exchanger 52b all function as refrigerant radiators and the outdoor heat exchanger 23 functions as a refrigerant evaporator. The first gas-side shutoff valve 58a and the second gas-side shutoff valve 58b are fully open. The subcooling expansion valve 44 is, for example, fully closed. The first on-off valve 63a and the second on-off valve 63b are fully closed except when thermo-off control, which will be described later, is being performed. The valve opening of the subcooling expansion valve 44 may be controlled to satisfy a predetermined condition, such as the degree of superheat of the refrigerant drawn into the compressor 21 being equal to or greater than a predetermined value.

[0095] The high-pressure refrigerant discharged from the compressor 21 flows out of the outdoor unit 2 through the switching valve 22 and the gas-side shut-off valve .

[0096] When the refrigerant flowing out from the outdoor unit 2 flows through the gas refrigerant communication pipe 6, it branches off at the gas side branch portion 6x to flow through the first gas side branch pipe portion 6a and the second gas side branch pipe portion 6b.

[0097] The refrigerant that flows through the first gas-side branch pipe 6a flows into the first indoor unit 3a and is sent to the first indoor heat exchanger 52a. The high-pressure refrigerant sent to the first indoor heat exchanger 52a is cooled and condensed in the first indoor heat exchanger 52a, which functions as a refrigerant radiator, by exchanging heat with indoor air supplied from the room by the first indoor fan 55a. The refrigerant is depressurized by the first indoor expansion valve 57a and then flows out of the first indoor unit 3a. The valve opening of the first indoor expansion valve 57a is controlled to satisfy a predetermined condition, such as the degree of subcooling of the refrigerant flowing through the liquid side of the first indoor heat exchanger 52a being equal to or greater than a predetermined value. The degree of subcooling may be calculated, for example, using the detection values ​​of the first indoor heat exchanger liquid-side sensor 71a and the discharge pressure sensor 36. The indoor air heated in the first indoor heat exchanger 52a is sent to the room, where the room targeted by the first indoor unit 3a is heated.

[0098] Meanwhile, the refrigerant that flows through the second gas-side branch pipe 6b flows into the second indoor unit 3b and is sent to the second indoor heat exchanger 52b. The high-pressure refrigerant sent to the second indoor heat exchanger 52b is cooled and condensed in the second indoor heat exchanger 52b, which functions as a refrigerant radiator, by exchanging heat with indoor air supplied from the room by the second indoor fan 55b. The refrigerant is depressurized by the second indoor expansion valve 57b and then flows out of the second indoor unit 3b. The valve opening of the second indoor expansion valve 57b is controlled to satisfy a predetermined condition, such as the degree of subcooling of the refrigerant flowing through the liquid side of the second indoor heat exchanger 52b being equal to or greater than a predetermined value. The degree of subcooling may be calculated, for example, using the detection values ​​of the second indoor heat exchanger liquid-side sensor 71b and the discharge pressure sensor 36. The indoor air heated in the second indoor heat exchanger 52b is sent to the room, where the room targeted by the second indoor unit 3b is heated.

[0099] The refrigerant flowing out of the first indoor unit 3a and the refrigerant flowing out of the second indoor unit 3b then join in the liquid refrigerant connection pipe 5 and is sent to the outdoor unit 2. The refrigerant sent to the outdoor unit 2 passes through a liquid-side shut-off valve 27, is decompressed in the outdoor expansion valve 25, and flows into the outdoor heat exchanger 23. The valve opening of the outdoor expansion valve 25 is controlled to satisfy predetermined conditions, such as the degree of superheat of the refrigerant drawn into the compressor 21 being equal to or greater than a predetermined value, or the degree of superheat of the refrigerant discharged from the compressor 21 being equal to or greater than a predetermined value. The degree of superheat of the discharged refrigerant may be calculated using, for example, the detection values ​​of a discharge pressure sensor 36 and a discharge temperature sensor 37. The refrigerant sent to the outdoor heat exchanger 23 is heated by heat exchange with outdoor air supplied by the outdoor fan 24 and evaporates. The evaporated refrigerant is drawn into the compressor 21 through the switching valve 22 and the accumulator 29.

[0100] In the first indoor unit 3a, thermostat-off control is performed when a predetermined condition is met, such as when the difference between the set temperature of the first indoor unit 3a and the detected value of the first indoor air sensor 73a is equal to or smaller than a predetermined value. During thermostat-off control of the first indoor unit 3a, the first on-off valve 63a is controlled to an open state, the first gas-side shutoff valve 58a is maintained open, and the controlled state of the first indoor expansion valve 57a is also maintained. As a result, the refrigerant flowing through the first bypass circuit 61a is decompressed as it passes through the first pressure reducing section 62a. After passing through the first on-off valve 63a, which is controlled to an open state, the refrigerant passes through the first check valve 64a and flows out of the first indoor unit 3a. Therefore, in the first indoor unit 3a, refrigerant can be preferentially passed through the first bypass circuit 61a rather than the first indoor heat exchanger 52a, thereby suppressing heat exchange in the first indoor heat exchanger 52a. Note that the first gas-side shutoff valve 58a is maintained in an open state, and the first indoor expansion valve 57a is not controlled to a closed state, and heating control continues, so that a state in which refrigerant passes through the first indoor expansion valve 57a as well is maintained. This prevents liquid refrigerant from accumulating in the first indoor heat exchanger 52a, and suppresses a shortage of refrigerant in the refrigerant circuit 10. In particular, because the first indoor fan 55a of the present embodiment is operated to maintain a constant air speed, when refrigerant is present in the first indoor heat exchanger 52a, condensation of the refrigerant tends to occur, and liquid refrigerant tends to accumulate in the first indoor heat exchanger 52a. However, because a state in which refrigerant passes through the first indoor expansion valve 57a is maintained as described above, a shortage of refrigerant in the refrigerant circuit 10 is suppressed even when the first indoor fan 55a is kept driven. Furthermore, by keeping the first indoor fan 55a in operation even during thermo-off control, air from the space targeted by the first indoor unit 3a can continue to be supplied to the area around the first indoor air sensor 73a, thereby improving the accuracy of indoor temperature detection.The thermo-off control ends when a predetermined condition is met, such as the difference between the detected value of the first indoor air sensor 73a and the set temperature being equal to or greater than a predetermined value.

[0101] Similarly, in the second indoor unit 3b, thermostat-off control is performed when a predetermined condition is met, such as when the difference between the set temperature of the second indoor unit 3b and the detected value of the second indoor air sensor 73b is equal to or less than a predetermined value. During thermostat-off control for the second indoor unit 3b, the second on-off valve 63b is controlled to an open state, the second gas-side shutoff valve 58b is maintained open, and the controlled state of the second indoor expansion valve 57b is also maintained. As a result, the refrigerant flowing through the second bypass circuit 61b is reduced in pressure as it passes through the second pressure reducing section 62b. After passing through the second on-off valve 63b, which is controlled to an open state, the refrigerant passes through the second check valve 64b and flows out of the second indoor unit 3b. Therefore, in the second indoor unit 3b, refrigerant can be preferentially passed through the second bypass circuit 61b rather than the second indoor heat exchanger 52b, thereby suppressing heat exchange in the second indoor heat exchanger 52b. Note that the second gas-side shutoff valve 58b is maintained in an open state, and the second indoor expansion valve 57b is not controlled to a closed state, and heating control continues, so that a state in which refrigerant passes through the second indoor expansion valve 57b as well is maintained. This prevents liquid refrigerant from accumulating in the second indoor heat exchanger 52b, and prevents a shortage of refrigerant in the refrigerant circuit 10. In particular, because the second indoor fan 55b of the present embodiment is operated to maintain a constant air speed, when refrigerant is present in the second indoor heat exchanger 52b, condensation of the refrigerant tends to occur, and liquid refrigerant tends to accumulate in the second indoor heat exchanger 52b. However, because a state in which refrigerant passes through the second indoor expansion valve 57b is maintained as described above, a shortage of refrigerant in the refrigerant circuit 10 is prevented even when the second indoor fan 55b is kept driven. Furthermore, by maintaining the second indoor fan 55b in a driven state even during thermo-off control, air from the space targeted by the second indoor unit 3b can continue to be supplied to the area around the second indoor air sensor 73b, thereby improving the accuracy of indoor temperature detection.The thermo-off control ends when a predetermined condition is met, such as the difference between the detected value of the second indoor air sensor 73b and the set temperature being equal to or greater than a predetermined value.

[0102] (3) Operation of air conditioners in the event of a refrigerant leak The operation of the air conditioner 1 in the event of a refrigerant leak will be explained below using the control flow shown in Figure 4. Note that the operation of the air conditioner 1 in the event of a refrigerant leak, which will be explained below, is performed by the control unit 7, which controls the components of the air conditioner 1, in the same way as the basic operation described above.

[0103] Note that similar control is performed regardless of which of the multiple indoor units a refrigerant leak is detected in. Therefore, here we will explain the example of when a refrigerant leak is detected in the first indoor unit 3a, specifically, when a refrigerant leak is detected in the first refrigerant leak sensor 74a.

[0104] In step S1, it is determined whether a refrigerant leak has been detected by either the first refrigerant leak sensor 74a of the first indoor unit 3a or the second refrigerant leak sensor 74b of the second indoor unit 3b. If a refrigerant leak has been detected by either the first refrigerant leak sensor 74a or the second refrigerant leak sensor 74b, the process proceeds to the next step S2.

[0105] In step S2, the indoor expansion valve and gas-side shutoff valve (here, the first indoor expansion valve 57a and the first gas-side shutoff valve 58a) of the indoor unit having the refrigerant leak sensor in which a refrigerant leak was detected (here, the first indoor unit 3a having the first refrigerant leak sensor 74a that detected a refrigerant leak) are controlled to a closed state, and the indoor unit in which a refrigerant leak was detected is isolated from the refrigerant circuit 10. This essentially cuts off the supply of refrigerant to the indoor heat exchanger of the indoor unit in which a refrigerant leak was detected, and the process proceeds to step S3.

[0106] In step S3, the operation of all units, including the other indoor units in which a refrigerant leak has not been detected and the outdoor unit 2, is stopped.

[0107] (4) Features of the embodiment (4-1) In the first indoor unit 3a of this embodiment, when refrigerant leakage is detected, the first indoor expansion valve 57a and the first gas-side shutoff valve 58a are controlled to a closed state. Here, when both the first indoor expansion valve 57a and the first gas-side shutoff valve 58a are in a closed state and the differential pressure between the front and rear air is 1.0 MPa, the leakage amount when the valves are closed is 300 cm 3 / min or less, it is possible to substantially stop the supply of refrigerant from other parts of the refrigerant circuit 10 to the first indoor heat exchanger 52a.

[0108] Similarly, for the second indoor unit 3b, the second indoor expansion valve 57b and the second gas-side shutoff valve 58b are both closed, and the leakage amount when the differential pressure between the front and rear air is 1.0 MPa is 300 cm 3 / min or less, when a refrigerant leak is detected, the supply of refrigerant from other parts of the refrigerant circuit 10 to the second indoor heat exchanger 52b can be substantially stopped.

[0109] The shutoff performance of the first indoor expansion valve 57a, first gas side shutoff valve 58a, second indoor expansion valve 57b, and second gas side shutoff valve 58b meets the standards required for R32, a mildly flammable (A2L) refrigerant (see "Appendix A (Regulations) Specifications for Safety Shutoff Valves" in the "Facility Guidelines for Ensuring Safety in the Event of Refrigerant Leakage from Commercial Air Conditioners Using Mildly Flammable (A2L) Refrigerants" (JRA GL-16:2017), a guideline issued by the Japan Refrigeration and Air Conditioning Industry Association on September 1, 2017). As a result, even if a refrigerant leak occurs in the first indoor unit 3a or the second indoor unit 3b, the degree to which refrigerant leaks through the valve gaps of the first indoor expansion valve 57a, the first gas side shut-off valve 58a, the second indoor expansion valve 57b, and the second gas side shut-off valve 58b can be kept sufficiently low, making it possible to keep the refrigerant concentration in the air-conditioned space sufficiently below the lower flammability limit (LFL).

[0110] In the first indoor unit 3a, the first indoor expansion valve 57a is provided in the first indoor liquid refrigerant pipe 53a, between the first liquid-side bypass connection portion 66a and the first indoor heat exchanger 52a, and the first gas-side shutoff valve 58a is provided in the first indoor gas refrigerant pipe 54a, between the first gas-side bypass connection portion 65a and the first indoor heat exchanger 52a. Therefore, if the first indoor expansion valve 57a and the first gas-side shutoff valve 58a are controlled to the closed state when a refrigerant leak is detected in the first indoor unit 3a, refrigerant is prevented from being supplied to the first indoor heat exchanger 52a, even if refrigerant leaks through the first on-off valve 63a and the first check valve 64a in the first bypass circuit 61a.

[0111] Similarly, in the second indoor unit 3b, a second indoor expansion valve 57b is provided in the second indoor liquid refrigerant pipe 53b, between the second liquid-side bypass connection portion 66b and the second indoor heat exchanger 52b, and a second gas-side shutoff valve 58b is provided in the second indoor gas refrigerant pipe 54b, between the second gas-side bypass connection portion 65b and the second indoor heat exchanger 52b. Therefore, if the second indoor expansion valve 57b and the second gas-side shutoff valve 58b are controlled to the closed state when a refrigerant leak is detected in the second indoor unit 3b, refrigerant is prevented from being supplied to the second indoor heat exchanger 52b, even if refrigerant leaks through the second on-off valve 63b and the second check valve 64b in the second bypass circuit 61b.

[0112] Therefore, the first on-off valve 63a, the first check valve 64a, the second on-off valve 63b, and the second check valve 64b can be inexpensive valves with low shutoff performance.

[0113] (5) Other embodiments (5-1) In the above description of the embodiment, R32 has been used as an example of the refrigerant used in the air conditioner 1.

[0114] In contrast, the refrigerant used in the air conditioning device 1 is not limited to this, and may be, for example, a flammable refrigerant deemed to be "2L class" according to the US ANSI / ASHRAE34-2013 standard, a weakly flammable refrigerant deemed to be "Class 2" according to the US ANSI / ASHRAE34-2013 standard, or a highly flammable refrigerant deemed to be "Class 3" according to the US ANSI / ASHRAE34-2013 standard.

[0115] In this case, it is preferable to use an indoor expansion valve and a gas-side shutoff valve that have the shutoff performance required according to the type of refrigerant used in the air conditioner 1.

[0116] (5-2) In the above embodiment, a floor-standing indoor unit that is installed on the floor of a space to be air-conditioned has been described as an example of the indoor unit.

[0117] On the other hand, the indoor unit is not limited to this, and may be, for example, a type that is embedded in the ceiling of the space to be air-conditioned, or a type that is suspended from the ceiling.

[0118] (5-3) In the above embodiment, the thermo-off control during heating operation is described as an example in which the controlled states of the first indoor expansion valve 57a and the second indoor expansion valve 57b provided in the indoor unit subjected to the thermo-off control are maintained.

[0119] In response to this, for example, the first indoor expansion valve 57a and the second indoor expansion valve 57b provided in the indoor unit subjected to thermo-off control may be controlled to a closed state, and control may be performed so that refrigerant flows through the first bypass circuit 61a and the second bypass circuit 61b. This makes it possible to prevent a situation in which air that has passed through the first indoor heat exchanger 52a and the second indoor heat exchanger 52b and been heated is supplied to the room even during thermo-off control.

[0120] (5-4) In the above embodiment, an example was given in which the indoor expansion valve and gas side shut-off valve of the indoor unit in which a refrigerant leak was detected are controlled to a closed state, and the opening / closing valve of the bypass circuit of the indoor unit in which a refrigerant leak was detected is not particularly controlled.

[0121] Alternatively, for example, for an indoor unit in which a refrigerant leak has been detected, the on-off valve of the bypass circuit may be first controlled to the open state, and then the indoor expansion valve and gas-side shutoff valve may be controlled to the closed state. Alternatively, for an indoor unit in which a refrigerant leak has been detected, the on-off valve of the bypass circuit may be controlled to the open state and the indoor expansion valve and gas-side shutoff valve may be controlled to the closed state simultaneously. If the time required to change the on-off valve from the closed state to the open state is shorter than the time required to close the indoor expansion valve and gas-side shutoff valve, the high-pressure refrigerant in the refrigerant circuit 10 can pass through the bypass circuit, thereby reducing the high-pressure pressure and reducing the refrigerant pressure acting on the leak location. This makes it possible to keep the initial leakage amount small when a refrigerant leak is detected.

[0122] (Addendum) Although the embodiments of the present disclosure have been described above, it will be understood that various changes in form and details can be made without departing from the spirit and scope of the present disclosure as defined in the claims. [Explanation of symbols]

[0123] 1. Air conditioning equipment 5 Liquid refrigerant connection piping (liquid refrigerant piping) 5a First liquid-side branch pipe section (liquid-side refrigerant piping, liquid-side branch section, first liquid-side branch section) 5b Second liquid side branch pipe section (liquid side refrigerant piping, liquid side branch section, second liquid side branch section) 5m Liquid side main pipe section (liquid side refrigerant piping, liquid side main pipe) 5x Liquid side branch section (liquid side refrigerant piping) 6 Gas refrigerant connecting piping (gas side refrigerant piping) 6a First gas side branch pipe section (gas side refrigerant piping, gas side branch section, first gas side branch section) 6b Second gas side branch pipe section (gas side refrigerant piping, gas side branch section, second gas side branch section) 6m gas side main pipe (gas side refrigerant piping, gas side main pipe) 6x Gas side branch section (gas side refrigerant piping) 7 Control Unit 10 Refrigerant circuit 30a First indoor casing (indoor casing) 30b Second indoor casing (indoor casing) 52a 1st indoor heat exchanger (indoor heat exchanger) 52b 2nd indoor heat exchanger (indoor heat exchanger) 53a First indoor liquid refrigerant pipe (liquid side refrigerant piping, first liquid side branch part) 53b Second indoor liquid refrigerant pipe (liquid side refrigerant piping, second liquid side branch part) 54a First indoor gas refrigerant pipe (gas side refrigerant piping, first gas side branch part) 54b Second indoor gas refrigerant pipe (gas side refrigerant piping, second gas side branch part) 57a No. 1 indoor expansion valve (liquid side shutoff valve, No. 1 liquid side shutoff valve) 57b Second indoor expansion valve (liquid side shutoff valve, second liquid side shutoff valve) 58a First gas side shutoff valve (gas side shutoff valve, first gas side shutoff valve) 58b Second gas side shutoff valve (gas side shutoff valve, second gas side shutoff valve) 61a First bypass circuit (bypass circuit) 61b Second bypass circuit (bypass circuit) 63a First opening / closing valve (bypass valve, first bypass valve) 63b Second on-off valve (bypass valve, second bypass valve) 65a First gas side bypass connection part 65b Second gas side bypass connection part 66a First liquid side bypass connection part 66b Second liquid side bypass connection part 74a First refrigerant leak sensor (refrigerant leak sensor) 74b Second refrigerant leak sensor (refrigerant leak sensor) [Prior art documents] [Patent documents]

[0124] [Patent Document 1] International Publication No. 2018 / 04249

Claims

1. An air conditioner (1) including a refrigerant circuit (10) in which a compressor (21), gas-side refrigerant piping (6, 6m, 6a, 6b, 54a, 54b), an outdoor heat exchanger (23), liquid-side refrigerant piping (5, 5m, 5a, 5b, 53a, 53b), and indoor heat exchangers (52a, 52b) are connected, and which performs a refrigeration cycle by circulating a refrigerant, The refrigerant circuit includes: a bypass circuit (61a, 61b) connecting a gas side bypass connection portion (65a, 65b) of the gas side refrigerant piping and a liquid side bypass connection portion (66a, 66b) of the liquid side refrigerant piping; a gas-side shutoff valve (58a, 58b) provided in the gas-side refrigerant piping between the indoor heat exchanger and the gas-side bypass connection portion; a liquid-side shutoff valve (57a, 57b) provided in the liquid-side refrigerant piping between the indoor heat exchanger and the liquid-side bypass connection portion; It has Air conditioning equipment.

2. The gas-side shutoff valve has a leakage amount of 300 cm when the gas-side shutoff valve is closed and the differential pressure of the air before and after the valve is 1.0 MPa. ３ / min or less, The liquid-side shutoff valve has a closed valve leakage amount of 300 cm when the liquid-side shutoff valve is closed and the differential pressure of the air before and after the valve is 1.0 MPa. ３ / min or less, The air conditioning apparatus according to claim 1.

3. The bypass circuit has bypass valves (63a, 63b), The bypass valve has a leakage amount of 300 cm when the bypass valve is closed and the differential pressure between the front and rear air is 1.0 MPa. ３ / min more valves, The air conditioning apparatus according to claim 1 or 2.

4. the indoor heat exchanger includes a first indoor heat exchanger (52a) and a second indoor heat exchanger (52b) connected in parallel to each other in the refrigerant circuit, the gas side refrigerant piping includes a gas side main pipe (6m), a gas side branch portion (6x), a first gas side branch portion (6a, 54a) extending from the gas side branch portion toward the first indoor heat exchanger, and a second gas side branch portion (6b, 54b) extending from the gas side branch portion toward the second indoor heat exchanger, the liquid-side refrigerant piping includes a liquid-side main pipe (5m), a liquid-side branch portion (5x), a first liquid-side branch portion (5a, 53a) extending from the liquid-side branch portion toward the first indoor heat exchanger, and a second liquid-side branch portion (5b, 53b) extending from the liquid-side branch portion toward the second indoor heat exchanger, the bypass circuit includes a first bypass circuit (61a) that connects a first gas side bypass connecting portion (65a) of the first gas side branch portion and a first liquid side bypass connecting portion (66a) of the first liquid side branch portion and has a first bypass valve (63a); and a second bypass circuit (61b) that connects a second gas side bypass connecting portion (65b) of the second gas side branch portion and a second liquid side bypass connecting portion (66b) of the second liquid side branch portion and has a second bypass valve (63b), The gas-side shutoff valve includes a first gas-side shutoff valve (58a) provided in the first gas-side branch portion between the indoor heat exchanger and the first gas-side bypass connecting portion, and a second gas-side shutoff valve (58b) provided in the second gas-side branch portion between the indoor heat exchanger and the second gas-side bypass connecting portion, The liquid-side shutoff valve includes a first liquid-side shutoff valve (57a) provided in the first liquid-side branch portion between the indoor heat exchanger and the first liquid-side bypass connection portion, and a second liquid-side shutoff valve (57b) provided in the second liquid-side branch portion between the indoor heat exchanger and the second liquid-side bypass connection portion. The air conditioning apparatus according to claim 3.

5. When the refrigerant leaks in a flow path from the first gas side shutoff valve through the first indoor heat exchanger to the first liquid side shutoff valve, the first gas side shutoff valve and the first liquid side shutoff valve are closed, and when the refrigerant leaks in a flow path from the second gas side shutoff valve through the second indoor heat exchanger to the second liquid side shutoff valve, the second gas side shutoff valve and the second liquid side shutoff valve are closed. The air conditioning apparatus according to claim 4.

6. An operation in which the opening degree of the first bypass valve is increased to reduce the flow rate of the refrigerant in the first indoor heat exchanger, and an operation in which the opening degree of the second bypass valve is increased to reduce the flow rate of the refrigerant in the second indoor heat exchanger are possible. The air conditioning apparatus according to claim 5.

7. The system further includes an indoor casing (30a, 30b) that accommodates the indoor heat exchanger and the gas-side shutoff valve therein. The air conditioning apparatus according to claim 1 or 2.

8. The liquid-side shutoff valve is accommodated inside the indoor casing. The air conditioning apparatus according to claim 7.

9. The cooling system further includes refrigerant leakage sensors (74a, 74b) provided in the indoor casing. The air conditioning apparatus according to claim 7.

10. The refrigerant includes R32. The air conditioning apparatus according to claim 1 or 2.

Images