JP6922748B2 - Air conditioner - Google Patents

Description

The present invention is connected to an air conditioner, particularly an outdoor unit, a plurality of indoor units, a liquid refrigerant connecting pipe and a gas refrigerant connecting pipe, and a liquid connecting pipe and a gas refrigerant connecting pipe connected to the liquid refrigerant connecting pipe. The present invention relates to a relay unit having a relay shutoff valve in a gas connecting pipe, a refrigerant leak detecting means for detecting a refrigerant leak, and an air conditioner including the refrigerant leak detecting means.

Conventionally, an outdoor unit having a compressor, a plurality of indoor units having an indoor expansion valve and an indoor heat exchanger, a liquid refrigerant connecting pipe and a gas refrigerant connecting pipe connecting the outdoor unit and the indoor unit, and a liquid refrigerant have been used. An air conditioner that is provided on the connecting pipe and the gas refrigerant connecting pipe and includes at least one relay unit that switches a plurality of indoor heat exchangers individually to function as a refrigerant evaporator or a refrigerant radiator. be. As such an air conditioner, as shown in Patent Document 1 (Patent No. 5517789), the liquid connection pipe (refrigerant pipe connected to the liquid-refrigerant communication pipe) and the gas connection pipe (gas-refrigerant communication) of the relay unit are used. A relay shutoff valve (liquid relay shutoff valve and gas relay shutoff valve) is provided in the refrigerant pipe connected to the pipe), and the liquid relay shutoff valve and gas relay shutoff valve are closed when the refrigerant leaks, thereby allowing the outdoor unit to enter the room. The inflow of the refrigerant to the unit side is prevented, and the leakage of the refrigerant from the indoor unit is suppressed.

In the configuration of Patent Document 1, the liquid relay shutoff valve and the gas relay shutoff valve of the relay unit are closed when the refrigerant leaks, so that the portion between the liquid relay shutoff valve including the indoor unit and the gas relay shutoff valve is closed. I try to separate it. As a result, the portion where the refrigerant leaks is limited to the portion between the liquid relay shutoff valve and the gas relay shutoff valve including the indoor unit.

However, closing the liquid relay shutoff valve and the gas relay shutoff valve of the relay unit allows the leakage of the refrigerant existing in the portion between the liquid relay shutoff valve including the indoor unit and the gas relay shutoff valve. This means that it is not sufficient from the viewpoint of reducing the amount of leakage.

An object of the present invention is an outdoor unit, a plurality of indoor units, a liquid-refrigerant connecting pipe and a gas-refrigerant connecting pipe, and a liquid-refrigerant connecting pipe connected to the liquid-refrigerant connecting pipe and a gas connecting pipe connected to the gas-refrigerant connecting pipe. An air conditioner including a relay unit having a relay shutoff valve, a refrigerant leakage detecting means for detecting a refrigerant leakage, and an air conditioner including the above is to reduce the amount of refrigerant leakage when the refrigerant leaks.

The air conditioner according to the first aspect includes an outdoor unit, a plurality of indoor units, a liquid refrigerant connecting pipe and a gas refrigerant connecting pipe, at least one relay unit, a refrigerant leak detecting means, and a control unit. Have. The outdoor unit has a compressor. The indoor unit has an indoor expansion valve and an indoor heat exchanger. The liquid-refrigerant connecting pipe and the gas-refrigerant connecting pipe connect the outdoor unit and the indoor unit. The relay unit is provided in the liquid refrigerant connecting pipe and the gas refrigerant connecting pipe, and the liquid relay shutoff valve is connected to the liquid connecting pipe connected to the liquid refrigerant connecting pipe and the gas is relayed to the gas connecting pipe connected to the gas refrigerant connecting pipe. It has a shutoff valve, and switches a plurality of indoor heat exchangers individually so as to function as a refrigerant evaporator or a refrigerant radiator. The refrigerant leakage detecting means detects the leakage of the refrigerant. The control unit controls the components of the outdoor unit, the indoor unit, and the relay unit. Then, here, the control unit opens the liquid relay shutoff valve and closes the indoor expansion valve and the gas relay shutoff valve based on the information of the refrigerant leak detecting means when the refrigerant leaks, and performs the first shutoff control.

Here, as described above, when the refrigerant leaks, the indoor expansion valve and the gas relay shutoff valve are closed with the liquid relay shutoff valve open by the first shutoff control, so that there is a high possibility of the refrigerant leaking. Only the part between the indoor expansion valve including the indoor heat exchanger and the gas relay shutoff valve is separated. As a result, the portion where the refrigerant leaks is limited to the portion between the indoor expansion valve including the indoor heat exchanger and the gas relay shutoff valve. This is compared to the case where the liquid relay shutoff valve and the gas relay shutoff valve of the relay unit are closed when the refrigerant leaks, so that the part between the liquid relay shutoff valve including the indoor unit and the gas relay shutoff valve is separated. This means that the part where the refrigerant leaks can be narrowed while including the indoor heat exchanger where there is a high possibility of the refrigerant leaking.

As described above, here, by performing the first shutoff control when the refrigerant leaks, a narrow portion between the indoor expansion valve including the indoor heat exchanger and the gas relay shutoff valve, which has a high possibility of refrigerant leak, is performed. Can be separated, and the amount of refrigerant leakage can be reduced.

In the air conditioner according to the second aspect, in the air conditioner according to the first aspect, the liquid relay shutoff valve is composed of an electric expansion valve, and the control unit slightly adjusts the liquid relay shutoff valve during the first shutoff control. Open it. Here, "slightly open" is an opening degree of about 15% or less when the fully open liquid relay shutoff valve is expressed as 100%.

Refrigerant leakage is less likely than in the vicinity of the indoor heat exchanger (the part between the indoor expansion valve including the indoor heat exchanger and the gas relay shutoff valve), but between the liquid relay shutoff valve and the indoor expansion valve. It may also occur from the part in between. Therefore, even when only the portion between the indoor expansion valve including the indoor heat exchanger and the gas relay shutoff valve is separated by the first shutoff control, the portion between the liquid relay shutoff valve and the indoor expansion valve is used. Assuming leakage of the refrigerant, it is preferable to reduce the inflow of the refrigerant from the outdoor unit side to the portion between the liquid relay shutoff valve and the indoor expansion valve.

Therefore, here, as described above, at the time of the first shutoff control, the liquid relay shutoff valve composed of the electric expansion valve is slightly opened, and the portion between the liquid relay shutoff valve and the indoor expansion valve is transferred from the outdoor unit side. The inflow of refrigerant is reduced.

As a result, here, even if the refrigerant leaks from the portion between the liquid relay shutoff valve and the indoor expansion valve, the refrigerant leaks from this portion as much as possible during the first shutoff control. It can be suppressed.

The air conditioner according to the third aspect is the air conditioner according to the first or second aspect, when the control unit determines that the leakage of the refrigerant continues even if the first cutoff control is performed. , The second shutoff control for closing the liquid relay shutoff valve is performed while the indoor expansion valve is closed.

If the refrigerant continues to leak even after disconnecting only the part between the indoor expansion valve including the indoor heat exchanger and the gas relay shutoff valve by the first shutoff control, the refrigerant leaks and the liquid relay shutoff. It may be generated from the part between the valve and the indoor expansion valve.

Therefore, here, as described above, when it is determined that the refrigerant continues to leak even if the first shutoff control is performed, the liquid relay shutoff valve is kept closed by the second shutoff control. Is closed to separate the part between the liquid relay shutoff valve and the indoor expansion valve.

Thereby, here, when the refrigerant leaks, the portion between the liquid relay shutoff valve and the indoor expansion valve can be separated by performing the second shutoff control following the first shutoff control, and the amount of the refrigerant leaked. Can be reduced.

In the air conditioner according to the fourth aspect, in the air conditioner according to the third aspect, the indoor unit further has a temperature sensor for detecting the temperature of the refrigerant in the vicinity of the indoor heat exchanger, and the control unit has a control unit. Based on the temperature of the refrigerant detected by the temperature sensor during the first shutoff control, it is determined whether or not the refrigerant continues to leak even if the first shutoff control is performed.

If refrigerant leaks near the indoor heat exchanger (the part between the indoor expansion valve including the indoor heat exchanger and the gas relay shutoff valve), when the first shutoff control is performed, the vicinity of the indoor heat exchanger Compared to the case where the refrigerant does not leak, the temperature of the refrigerant near the indoor heat exchanger tends to change rapidly due to the leakage of the refrigerant, and the ambient temperature in which the indoor heat exchanger is arranged also appears. It quickly approaches (room temperature, etc.). For example, when the rate of change in the temperature of the refrigerant near the indoor heat exchanger becomes larger than the predetermined rate of change, or when the temperature of the refrigerant near the indoor heat exchanger reaches a predetermined temperature determined by the ambient temperature within a predetermined time. In this case, the refrigerant leaks near the indoor heat exchanger, and the rate of change in the temperature of the refrigerant near the indoor heat exchanger is less than or equal to the predetermined rate of change, or the rate of change of the refrigerant near the indoor heat exchanger. If the temperature does not reach a predetermined temperature determined by the ambient temperature within a predetermined time, no refrigerant leaks in the vicinity of the indoor heat exchanger, that is, even if the first shutoff control is performed, the refrigerant leaks. Can be determined to be continued.

Thereby, here, it is possible to appropriately determine whether or not the leakage of the refrigerant continues even if the first cutoff control is performed.

In the air conditioner according to the fifth aspect, in the air conditioner according to the third or fourth aspect, the control unit opens the gas relay shutoff valve at the time of the second shutoff control.

If it is determined that the refrigerant continues to leak even after the first shutoff control is performed, the portion near the indoor heat exchanger (between the indoor expansion valve including the indoor heat exchanger and the gas relay shutoff valve). ), There is a high possibility that the refrigerant has not leaked.

Therefore, here, as described above, the gas relay shutoff valve is opened during the second shutoff control.

As a result, the state in which the portion between the indoor expansion valve and the gas relay shutoff valve is released can be released, and only the portion between the liquid relay shutoff valve and the indoor expansion valve can be released.

In the air conditioner according to the sixth aspect, in the air conditioner according to the fifth aspect, the gas relay shutoff valve is composed of an electric expansion valve, and the control unit slightly adjusts the gas relay shutoff valve during the second shutoff control. Open it. Here, "slightly open" is an opening degree of about 15% or less when the fully open gas relay shutoff valve is expressed as 100%.

Even if it is determined that the refrigerant continues to leak even after the first shutoff control is performed, the portion near the indoor heat exchanger (between the indoor expansion valve including the indoor heat exchanger and the gas relay shutoff valve). ), The possibility that the refrigerant has leaked cannot be completely denied. Therefore, even when only the portion between the liquid relay shutoff valve and the indoor expansion valve is separated by the second shutoff control, it is assumed that the refrigerant leaks from the portion between the indoor expansion valve and the gas relay shutoff valve. It is preferable to reduce the inflow of the refrigerant from the outdoor unit side to the portion between the gas relay shutoff valve and the indoor expansion valve.

Therefore, here, as described above, during the second shutoff control, the gas relay shutoff valve composed of the electric expansion valve is slightly opened, and the portion between the gas relay shutoff valve and the indoor expansion valve is reached from the outdoor unit side. The inflow of refrigerant is reduced.

As a result, here, even if the refrigerant leaks from the portion between the indoor expansion valve and the gas relay shutoff valve, the refrigerant leaks from this portion as much as possible during the second shutoff control. It can be suppressed.

As described above, according to the present invention, when the refrigerant leaks, the refrigerant is caused by closing the indoor expansion valve and the gas relay shutoff valve with the liquid relay shutoff valve open by the first shutoff control. Only the part between the indoor expansion valve including the indoor heat exchanger and the gas relay shutoff valve, which has a high possibility of leakage, can be separated, and the amount of refrigerant leakage can be reduced.

It is a schematic block diagram of the air conditioner which concerns on one Embodiment of this invention. It is a flowchart which shows the operation of the air conditioner at the time of the refrigerant leakage which concerns on one Embodiment of this invention. It is a flowchart which shows the operation of the air conditioner at the time of the refrigerant leakage which concerns on the modification 1 of this invention. It is a flowchart which shows the operation of the air conditioner at the time of the refrigerant leakage which concerns on the modification 2 of this invention. It is a flowchart which shows the operation of the air conditioner at the time of the refrigerant leakage which concerns on the modification 2 of this invention. It is a flowchart which shows the operation of the air conditioner at the time of the refrigerant leakage which concerns on the modification 3 of this invention. It is a flowchart which shows the operation of the air conditioner at the time of the refrigerant leakage which concerns on the modification 3 of this invention.

Hereinafter, embodiments of the air conditioner according to the present invention will be described with reference to the drawings. The specific configuration of the embodiment of the air conditioner according to the present invention is not limited to the following embodiments and modifications thereof, and can be changed without departing from the gist of the invention.

(1) Configuration The configuration of the air conditioner 1 will be described with reference to FIG. The air conditioner 1 is a device that cools and heats a room such as a building by a vapor compression refrigeration cycle. The air conditioner 1 mainly includes the outdoor unit 2, a plurality of (here, four) indoor units 3a, 3b, 3c, 3d connected in parallel to each other, and each indoor unit 3a, 3b, 3c, 3d. Refrigerant connecting pipes 5, 6 connecting the outdoor unit 2 and the indoor units 3a, 3b, 3c, and 3d via the relay units 4a, 4b, 4c, and 4d connected to the relay units 4a, 4b, 4c, and 4d. And a control unit 19 that controls the components of the outdoor unit 2, the indoor units 3a, 3b, 3c, 3d, and the relay units 4a, 4b, 4c, and 4d. The vapor compression type refrigerant circuit 10 of the air conditioner 1 includes the outdoor unit 2, the indoor units 3a, 3b, 3c, 3d, the relay units 4a, 4b, 4c, 4d, and the refrigerant connecting pipes 5 and 6. Is configured by being connected. The refrigerant circuit 10 is filled with a refrigerant such as R32. Then, in the air conditioner 1, the relay units 4a, 4b, 4c, and 4d enable each indoor unit 3a, 3b, 3c, and 3d to individually perform a cooling operation or a heating operation, and perform the heating operation. By sending refrigerant from the indoor unit to the indoor unit that performs the cooling operation, it is possible to recover heat between the indoor units (here, simultaneous cooling and heating operation in which the cooling operation and the heating operation are performed at the same time) becomes possible. It is configured.

<Refrigerant connecting pipe>
The liquid-refrigerant connecting pipe 5 mainly includes a merging pipe portion extending from the outdoor unit 2 and a first branch pipe portion 5a, 5b branched into a plurality of (here, four) in front of the relay units 4a, 4b, 4c, and 4d. It has a second branch pipe portion 5aa, 5bb, 5cc, 5dd that connects the relay units 4a, 4b, 4c, 4d and the indoor units 3a, 3b, 3c, and 3d.
Further, the gas refrigerant connecting pipe 6 mainly connects the high and low pressure gas refrigerant connecting pipe 7, the low pressure gas refrigerant connecting pipe 8, the relay units 4a, 4b, 4c and 4d, and the indoor units 3a, 3b, 3c and 3d. It has branch pipe portions 6a, 6b, 6c, and 6d. The high-low pressure gas-refrigerant connecting pipe 7 is a gas-refrigerant connecting pipe that can switch the connection to the discharge side or the suction side of the compressor 21 (described later), and has a merging pipe portion extending from the outdoor unit 2 and relay units 4a and 4b. It has branch pipe portions 7a, 7b, 7c, and 7d that are branched into a plurality of (here, four) in front of 4c and 4d. The low-pressure gas-refrigerant connecting pipe 8 is a gas-refrigerant connecting pipe connected to the suction side of the compressor 21 (described later), and is in front of the merging pipe portion extending from the outdoor unit 2 and the relay units 4a, 4b, 4c, and 4d. It has branch pipe portions 8a, 8b, 8c, and 8d branched into a plurality of (here, four). As described above, here, the gas refrigerant connecting pipe 6 has the high and low pressure gas refrigerant connecting pipe 7 and the low pressure gas refrigerant connecting pipe 8, so that the gas refrigerant connecting pipe 6 has three refrigerant connecting pipes including the liquid refrigerant connecting pipe 5 (so-called). 3 pipe type configuration).

<Indoor unit>
The indoor units 3a, 3b, 3c, and 3d are installed in a room such as a building. As described above, the indoor units 3a, 3b, 3c, and 3d include a liquid refrigerant connecting pipe 5 and a gas refrigerant connecting pipe 6 (high and low pressure gas refrigerant connecting pipe 7, low pressure gas refrigerant connecting pipe 8 and branch pipes 6a and 6b. It is connected to the outdoor unit 2 via the relay units 4a, 4b, 4c, and 4d) and the relay units 4a, 4b, 4c, and 4d, and constitutes a part of the refrigerant circuit 10.

Next, the configurations of the indoor units 3a, 3b, 3c, and 3d will be described. Since the indoor unit 3a and the indoor units 3b, 3c, and 3d have the same configuration, only the configuration of the indoor unit 3a will be described here, and the configurations of the indoor units 3b, 3c, and 3d will be described as the indoor units, respectively. Subscripts "b", "c" or "d" are added instead of the subscript "a" indicating each part of 3a, and the description of each part will be omitted.

The indoor unit 3a mainly has an indoor expansion valve 51a and an indoor heat exchanger 52a. Further, the indoor unit 3a includes an indoor liquid refrigerant pipe 53a that connects the liquid side end of the indoor heat exchanger 52a and the liquid refrigerant connecting pipe 5 (here, the branch pipe portion 5aa), and the gas side of the indoor heat exchanger 52a. It has an indoor gas refrigerant pipe 54a that connects the end and the gas refrigerant connecting pipe 6 (here, the branch pipe portion 6a).

The indoor expansion valve 51a is an electric expansion valve capable of adjusting the flow rate of the refrigerant flowing through the indoor heat exchanger 52a while reducing the pressure of the refrigerant, and is provided in the indoor liquid refrigerant pipe 53a.

The 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. Here, the indoor unit 3a has an indoor fan 55a for sucking indoor air into the indoor unit 3a, exchanging heat with the refrigerant in the indoor heat exchanger 52a, and then supplying the indoor air as supply air. There is. That is, the indoor unit 3a has an indoor fan 55a as a fan for supplying indoor air as a cooling source or a heating source of the refrigerant flowing through the indoor heat exchanger 52a to the indoor heat exchanger 52a. The indoor fan 55a is driven by the indoor fan motor 56a.

Various sensors are provided in the indoor unit 3a. Specifically, the indoor unit 3a includes an indoor heat exchange liquid side sensor 57a that detects the temperature Trl of the refrigerant at the liquid side end of the indoor heat exchanger 52a, and the temperature of the refrigerant at the gas side end of the indoor heat exchanger 52a. An indoor heat exchange gas side sensor 58a for detecting Trg and an indoor air sensor 59a for detecting the temperature Tra of the indoor air sucked into the indoor unit 3a are provided. Further, the indoor unit 3a is provided with a refrigerant sensor 79a as a refrigerant leakage detecting means for detecting the leakage of the refrigerant. Here, the refrigerant sensor 79a is provided in the indoor unit 3a, but the present invention is not limited to this, and the remote controller for operating the indoor unit 3a, the indoor space where the indoor unit 3a performs air conditioning, and the like can be used. It may be provided.

<Outdoor unit>
The outdoor unit 2 is installed outdoors such as a building. As described above, the outdoor unit 2 includes a liquid refrigerant connecting pipe 5, a gas refrigerant connecting pipe 6 (high / low pressure gas refrigerant connecting pipe 7, low pressure gas refrigerant connecting pipe 8 and branch pipes 6a, 6b, 6c, 6d) and a relay. It is connected to the indoor units 3a, 3b, 3c, and 3d via the units 4a, 4b, 4c, and 4d, and constitutes a part of the refrigerant circuit 10.

The outdoor unit 2 mainly includes a compressor 21 and one or more (here, two) outdoor heat exchangers 23a and 23b. Further, the outdoor unit 2 has a heat dissipation operation state in which the outdoor heat exchangers 23a and 23b function as a refrigerant radiator, and an evaporation operation state in which the outdoor heat exchangers 23a and 23b function as a refrigerant evaporator. It has switching mechanisms 22a and 22b for switching. The switching mechanisms 22a and 22b and the suction side of the compressor 21 are connected by a suction refrigerant pipe 31. The suction refrigerant pipe 31 is provided with an accumulator 29 that temporarily stores the refrigerant sucked into the compressor 21. The discharge side of the compressor 21 and the switching mechanisms 22a and 2b are connected by a discharge refrigerant pipe 32. The switching mechanism 22a and the gas side ends of the outdoor heat exchangers 23a and 23b are connected by the first outdoor gas refrigerant pipes 33a and 33b. The liquid side ends of the outdoor heat exchangers 23a and 23b and the liquid refrigerant connecting pipe 5 are connected by an outdoor liquid refrigerant pipe 34. A liquid side closing valve 27 is provided at a connection portion of the outdoor liquid refrigerant pipe 34 with the liquid refrigerant connecting pipe 5. Further, the outdoor unit 2 has a refrigerant derivation state in which the refrigerant discharged from the compressor 21 is sent to the high / low pressure gas refrigerant connecting pipe 7 and a refrigerant introduction state in which the refrigerant flowing through the high / low pressure gas refrigerant connecting pipe 7 is sent to the suction refrigerant pipe 31. It has a third switching mechanism 22c for switching between and. The third switching mechanism 22c and the high / low pressure gas refrigerant connecting pipe 7 are connected by a second outdoor gas refrigerant pipe 35. The third switching mechanism 22c and the suction side of the compressor 21 are connected by a suction refrigerant pipe 31. The discharge side of the compressor 21 and the third switching mechanism 22c are connected by a discharge refrigerant pipe 32. A high / low pressure gas side closing valve 28a is provided at a connection portion of the second outdoor gas refrigerant pipe 35 with the high / low pressure gas refrigerant connecting pipe 7. The suction refrigerant pipe 31 is connected to the low pressure gas refrigerant connecting pipe 8. A low-pressure gas side closing valve 28b is provided at the connection portion between the suction refrigerant pipe 31 and the low-pressure gas refrigerant connecting pipe 8. The liquid side closing valve 27 and the gas side closing valves 28a and 28b are valves that are manually opened and closed.

The compressor 21 is a device for compressing the refrigerant. For example, compression of a closed structure in which a positive displacement compression element (not shown) such as a rotary type or a scroll type is rotationally driven by a compressor motor 21a. The machine is used.

When the first outdoor heat exchanger 23a functions as a refrigerant radiator (hereinafter referred to as “outdoor heat dissipation state”), the first switching mechanism 22a is the discharge side of the compressor 21 and the first outdoor heat exchanger 23a. When connecting to the gas side of the above (see the solid line of the first switching mechanism 22a in FIG. 1) and allowing the first outdoor heat exchanger 23a to function as a refrigerant evaporator (hereinafter referred to as "outdoor evaporation state"). Switches the flow of the refrigerant in the refrigerant circuit 10 so as to connect the suction side of the compressor 21 and the gas side of the first outdoor heat exchanger 23a (see the broken line of the first switching mechanism 22a in FIG. 1). It is a device capable of, for example, consisting of a four-way switching valve. Further, when the second outdoor heat exchanger 23b functions as a refrigerant radiator (hereinafter referred to as "outdoor heat dissipation state"), the second switching mechanism 22b exchanges heat between the discharge side of the compressor 21 and the second outdoor heat exchanger. When connecting to the gas side of the vessel 23b (see the solid line of the second switching mechanism 22b in FIG. 1) and allowing the second outdoor heat exchanger 23b to function as a refrigerant evaporator (hereinafter, referred to as "outdoor evaporation state"). ) Is a flow of the refrigerant in the refrigerant circuit 10 so as to connect the suction side of the compressor 21 and the gas side of the second outdoor heat exchanger 23b (see the broken line of the second switching mechanism 22b in FIG. 1). It is a device that can be switched, and consists of, for example, a four-way switching valve. By changing the switching state of the switching mechanisms 22a and 22b, the outdoor heat exchangers 23a and 23b can be individually switched to function as a refrigerant evaporator or radiator.

The first outdoor heat exchanger 23a is a heat exchanger that functions as a radiator for the refrigerant or as an evaporator for the refrigerant. The second outdoor heat exchanger 23b is a heat exchanger that functions as a radiator for the refrigerant or as an evaporator for the refrigerant. Here, the outdoor unit 2 has an outdoor fan 24 for sucking outdoor air into the outdoor unit 2, exchanging heat with the refrigerant in the outdoor heat exchangers 23a and 23b, and then discharging the outdoor air to the outside. .. That is, the outdoor unit 2 has an outdoor fan 24 as a fan for supplying outdoor air as a cooling source or a heating source of the refrigerant flowing through the outdoor heat exchangers 23a and 23b to the outdoor heat exchangers 23a and 23b. Here, the outdoor fan 24 is driven by the outdoor fan motor 24a.

When the third switching mechanism 22c sends the refrigerant discharged from the compressor 21 to the high / low pressure gas refrigerant connecting pipe 7 (hereinafter referred to as “refrigerant derivation state”), the discharge side of the compressor 21 and the high / low pressure gas refrigerant When connecting to the connecting pipe 7 (see the broken line of the third switching mechanism 22c in FIG. 1) and sending the refrigerant flowing through the high / low pressure gas refrigerant connecting pipe 7 to the suction refrigerant pipe 31 (hereinafter, referred to as "refrigerant introduction state"). ) Is connected to the suction side of the compressor 21 and the high / low pressure gas refrigerant connecting pipe 7 (see the solid line of the third switching mechanism 22c in FIG. 1), so that the flow of the refrigerant in the refrigerant circuit 10 can be switched. Equipment, for example, consisting of a four-way switching valve.

Then, in the air conditioner 1, when focusing on the outdoor heat exchangers 23a and 23b, the liquid refrigerant connecting pipe 5, the relay units 4a, 4b, 4c and 4d and the indoor heat exchangers 52a, 52b, 52c and 52d, the refrigerant Is flowed from the outdoor heat exchangers 23a and 23b to the indoor heat exchangers 52a, 52b, 52c and 52d which function as refrigerant evaporators through the liquid refrigerant connecting pipes 5 and the relay units 4a, 4b, 4c and 4d (total cooling operation). And cooling-based operation). Here, the total cooling operation is an operating state in which only an indoor heat exchanger (that is, an indoor unit that performs the cooling operation) that functions as an evaporator of the refrigerant exists, and the cooling main operation is the evaporation of the refrigerant. Both the indoor heat exchanger functioning as a container and the indoor heat exchanger functioning as a refrigerant radiator (that is, the indoor unit that performs the heating operation) are mixed, but the load on the evaporation side as a whole (That is, the cooling load) is large in the operating state. Further, in the air conditioner 1, when focusing on the compressor 21, the gas refrigerant connecting pipe 6, the relay units 4a, 4b, 4c, 4d and the indoor heat exchangers 52a, 52b, 52c, 52d, the refrigerant is compressed by the compressor 21. Through the gas refrigerant connecting pipe 6 and the relay units 4a, 4b, 4c, and 4d to the indoor heat exchangers 52a, 52b, 52c, and 52d that function as refrigerant radiators (total heating operation and heating-based operation). It has become. Here, the full heating operation is an operating state in which only the indoor heat exchanger (that is, the indoor unit that performs the heating operation) that functions as a radiator of the refrigerant exists, and the heating main operation is the heat dissipation of the refrigerant. Both the indoor heat exchanger functioning as a container and the indoor heat exchanger functioning as a refrigerant evaporator are mixed, but as a whole, the load on the heat dissipation side (that is, the heating load) is large. Is. Here, at least one of the switching mechanisms 22a and 22b is switched to the outdoor heat dissipation state during the total cooling operation and the cooling main operation, and the outdoor heat exchangers 23a and 23b as a whole function as a refrigerant radiator and the liquid. The refrigerant flows from the outdoor unit 2 side to the indoor unit 3a, 3b, 3c, and 3d side through the refrigerant connecting pipe 5 and the relay units 4a, 4b, 4c, and 4d. Further, during the full heating operation and the main heating operation, at least one of the switching mechanisms 22a and 22b is switched to the outdoor evaporation state, and the third switching mechanism 22c is switched to the refrigerant derivation state, so that the outdoor heat exchangers 23a and 23b As a whole, it functions as a refrigerant evaporator, and the refrigerant flows from the indoor unit 3a, 3b, 3c, 3d side to the outdoor unit 2 side through the liquid refrigerant connecting pipe 5 and the relay units 4a, 4b, 4c, and 4d.

Further, here, the outdoor liquid refrigerant pipe 34 is provided with outdoor expansion valves 25a and 25b. The outdoor expansion valves 25a and 25b are electric expansion valves that reduce the pressure of the refrigerant during the full heating operation and the main heating operation, and are provided in the outdoor liquid refrigerant pipes 34 near the liquid side ends of the outdoor heat exchangers 23a and 23b. Has been done.

Further, here, the refrigerant return pipe 41 is connected to the outdoor liquid refrigerant pipe 34, and the refrigerant cooler 45 is provided. The refrigerant return pipe 41 is a refrigerant pipe that branches a part of the refrigerant flowing through the outdoor liquid refrigerant pipe 34 and sends it to the compressor 21. The refrigerant cooler 45 is a heat exchanger that cools the refrigerant flowing through the outdoor liquid refrigerant pipe 34 by the refrigerant flowing through the refrigerant return pipe 41. Here, the outdoor expansion valves 25a and 25b are provided on the outdoor heat exchangers 23a and 23b of the outdoor liquid refrigerant pipe 34 with respect to the refrigerant cooler 45.

The refrigerant return pipe 41 is a refrigerant pipe that sends the refrigerant branched from the outdoor liquid refrigerant pipe 34 to the suction side of the compressor 21. The refrigerant return pipe 41 mainly has a refrigerant return inlet pipe 42 and a refrigerant return outlet pipe 43. The refrigerant return inlet pipe 42 is a portion of the refrigerant flowing through the outdoor liquid refrigerant pipe 34 between the liquid side ends of the outdoor heat exchangers 23a and 23b and the liquid side closing valve 27 (here, the outdoor expansion valve 25a, It is a refrigerant pipe that branches from (a portion between 25b and the refrigerant cooler 45) and sends it to the inlet of the refrigerant cooler 45 on the refrigerant return pipe 41 side. The refrigerant return inlet pipe 42 is provided with a refrigerant return expansion valve 44 that adjusts the flow rate of the refrigerant flowing through the refrigerant cooler 45 while reducing the pressure of the refrigerant flowing through the refrigerant return pipe 41. Here, the refrigerant return expansion valve 44 includes an electric expansion valve. The refrigerant return outlet pipe 43 is a refrigerant pipe that is sent from the outlet on the refrigerant return pipe 41 side of the refrigerant cooler 45 to the suction refrigerant pipe 31. Moreover, the refrigerant return outlet pipe 43 of the refrigerant return pipe 41 is connected to the inlet side portion of the accumulator 29 in the suction refrigerant pipe 31. Then, the refrigerant cooler 45 is adapted to cool the refrigerant flowing through the outdoor liquid refrigerant pipe 34 by the refrigerant flowing through the refrigerant return pipe 41.

The outdoor unit 2 is provided with various sensors. Specifically, the outdoor unit 2 has a discharge pressure sensor 36 that detects the pressure of the refrigerant discharged from the compressor 21 (discharge pressure Pd) and the temperature of the refrigerant discharged from the compressor 21 (discharge temperature Td). A discharge temperature sensor 37 for detecting the pressure (suction pressure Ps) of the refrigerant sucked into the compressor 21 and a suction pressure sensor 39 for detecting the pressure (suction pressure Ps) are provided. Further, the outdoor unit 2 is provided with outdoor heat exchange liquid side sensors 38a and 38b for detecting the temperature Tol (outdoor heat exchange outlet temperature Tol) of the refrigerant at the liquid side ends of the outdoor heat exchangers 23a and 23b. There is.

<Relay unit>
The relay units 4a, 4b, 4c, and 4d are installed in a room such as a building. The relay units 4a, 4b, 4c, and 4d are together with the liquid refrigerant connecting pipe 5 and the gas refrigerant connecting pipe 6 (high and low pressure gas refrigerant connecting pipe 7, low pressure gas refrigerant connecting pipe 8 and branch pipes 6a, 6b, 6c, 6d). , 3a, 3b, 3c, 3d and the outdoor unit 2 are interposed between the indoor unit 3a, 3b, 3c, and 3d, and form a part of the refrigerant circuit 10.

Next, the configurations of the relay units 4a, 4b, 4c, and 4d will be described. Since the relay unit 4a and the relay units 4b, 4c, and 4d have the same configuration, only the configuration of the relay unit 4a will be described here, and the configurations of the relay units 4b, 4c, and 4d will be described as relay units, respectively. Instead of the subscript "a" of the code indicating each part of 4a, the subscript of "b", "c" or "d" is added, and the description of each part is omitted.

The relay unit 4a mainly has a liquid connection pipe 61a and a gas connection pipe 62a.

One end of the liquid connecting pipe 61a is connected to the first branch pipe portion 5a of the liquid refrigerant connecting pipe 5, and the other end is connected to the second branch pipe portion 5a of the liquid refrigerant connecting pipe 5. The liquid connection pipe 61a is provided with a liquid relay shutoff valve 71a. The liquid relay shutoff valve 71a is an electric expansion valve.

The gas connecting pipe 62a includes a high pressure gas connecting pipe 63a connected to the branch pipe portion 7a of the high and low pressure gas refrigerant connecting pipe 7 and a low pressure gas connecting pipe 64a connected to the branch pipe portion 8a of the low pressure gas refrigerant connecting pipe 8. It has a merging gas connecting pipe 65a for merging the high pressure gas connecting pipe 63a and the low pressure gas connecting pipe 64a. The merging gas connecting pipe 65a is connected to the branch pipe portion 6a of the gas refrigerant connecting pipe 6. The high-pressure gas connection pipe 63a is provided with a high-pressure gas relay shutoff valve 66a, and the low-pressure gas connection pipe 64a is provided with a low-pressure gas relay shutoff valve 67a. Here, the high-pressure gas relay shutoff valve 66a and the low-pressure gas relay shutoff valve 67a are composed of an electric expansion valve.

Then, when the indoor unit 3a performs the cooling operation, the relay unit 4a keeps the liquid relay shutoff valve 71a and the low pressure gas relay shutoff valve 67a open, and the first branch pipe portion 5a of the liquid refrigerant communication pipe 5 The refrigerant flowing into the liquid connecting pipe 61a through the liquid refrigerant connecting pipe 5 is sent to the indoor unit 3a through the second branch pipe portion 5aa of the liquid refrigerant connecting pipe 5, and then the refrigerant evaporated by heat exchange with the indoor air in the indoor heat exchanger 52a is transferred. It can function to return to the branch pipe portion 8a of the low pressure gas refrigerant connecting pipe 8 through the branch pipe portion 6a of the gas refrigerant connecting pipe 6, the merging gas connecting pipe 65a, and the low pressure gas connecting pipe 64a. Further, in the relay unit 4a, when the indoor unit 3a performs the heating operation, the low pressure gas relay shutoff valve 67a is closed, and the liquid relay shutoff valve 71a and the high pressure gas relay shutoff valve 66a are opened. The refrigerant flowing into the high pressure gas connecting pipe 63a and the merging gas connecting pipe 65a through the branch pipe portion 7a of the high and low pressure gas refrigerant connecting pipe 7 is sent to the indoor unit 3a through the branch pipe portion 6a of the gas refrigerant connecting pipe 6, and then indoors. The refrigerant radiated by heat exchange with the indoor air in the heat exchanger 52a is returned to the first branch pipe portion 5a of the liquid refrigerant connecting pipe 5 through the second branch pipe portion 5aa and the liquid connecting pipe 61a of the liquid refrigerant connecting pipe 5. Can function as. As described above, the high-pressure gas relay shutoff valve 66a and the low-pressure gas relay shutoff valve 67a are opened and closed when the indoor heat exchanger 52a is switched to function as a refrigerant evaporator or a refrigerant radiator. Since such a function is provided not only by the relay unit 4a but also by the relay units 4b, 4c, and 4d, the relay units 4a, 4b, 4c, and 4d use the indoor heat exchangers 52a and 52b. The 52c and 52d can be individually switched to function as a refrigerant evaporator or a refrigerant radiator.

<Control unit>
The control unit 19 is configured by transmitting and connecting control units (not shown) provided in the outdoor unit 2, the indoor units 3a, 3b, 3c, 3d, the relay units 4a, 4b, 4c, and 4d. There is. In FIG. 1, for convenience, it is shown at a position away from the outdoor unit 2, the indoor units 3a, 3b, 3c, 3d, and the relay units 4a, 4b, 4c, and 4d. The control unit 19 is an air conditioner 1 (here, here) based on the detection signals of various sensors 36, 37, 38a, 38b, 39, 57a to 57d, 58a to 58d, 59a to 59d, 79a to 79d as described above. , Outdoor unit 2, indoor unit 3a, 3b, 3c, 3d and relay unit 4a, 4b, 4c, 4d) Various components 21, 22a to 22c, 24, 25a, 25b, 44, 51a to 51d, 55a to 55d , 66a to 66d, 67a to 67d, 71a to 71d, that is, the operation control of the entire air conditioner 1 is performed.

(2) Basic operation of the air conditioner Next, the basic operation of the air conditioner 1 will be described with reference to FIG. As described above, the basic operations of the air conditioner 1 include full cooling operation, full heating operation, cooling main operation, and heating main operation. The basic operation of the air conditioner 1 described below controls the components of the air conditioner 1 (outdoor unit 2, indoor unit 3a, 3b, 3c, 3d and relay unit 4a, 4b, 4c, 4d). This is done by the control unit 19.

<Full cooling operation>
During the total cooling operation, for example, all of the indoor units 3a, 3b, 3c and 3d are in the cooling operation (that is, all of the indoor heat exchangers 52a, 52b, 52c and 52d function as refrigerant evaporators and are outdoors. When performing the operation in which the heat exchangers 23a and 23b function as the radiator of the refrigerant), the switching mechanisms 22a and 22b are switched to the outdoor heat dissipation state (the state shown by the solid line of the switching mechanisms 22a and 22b in FIG. 1). Then, the compressor 21, the outdoor fan 24, and the indoor fans 55a, 55b, 55c, 55d are driven. Further, the third switching mechanism 22c is switched to the refrigerant introduction state (the state shown by the solid line of the switching mechanism 22c in FIG. 1), and the liquid relay shutoff valves 71a, 71b, 71c of the relay units 4a, 4b, 4c, and 4d, 71d, the high-pressure gas relay shutoff valves 66a, 66b, 66c, 66d and the low-pressure gas relay shutoff valves 67a, 67b, 67c, 67d are opened.

Then, the high-pressure refrigerant discharged from the compressor 21 is sent to the outdoor heat exchangers 23a and 23b through the switching mechanisms 22a and 22b. The refrigerant sent to the outdoor heat exchangers 23a and 23b is cooled by exchanging heat with the outdoor air supplied by the outdoor fan 24 in the outdoor heat exchangers 23a and 23b that function as a radiator of the refrigerant. Condensate. This refrigerant flows out from the outdoor unit 2 through the outdoor expansion valves 25a and 25b, the refrigerant cooler 45, and the liquid side closing valve 27. At this time, in the refrigerant cooler 45, the refrigerant flowing out of the outdoor unit 2 is cooled by the refrigerant flowing through the refrigerant return pipe 41.

The refrigerant flowing out of the outdoor unit 2 is branched and sent to the relay units 4a, 4b, 4c, and 4d through the liquid refrigerant connecting pipe 5 (merging pipe portion and first branch pipe portion 5a, 5b, 5c, 5d). The refrigerant sent to the relay units 4a, 4b, 4c, and 4d flows out from the relay units 4a, 4b, 4c, and 4d through the liquid relay shutoff valves 71a, 71b, 71c, and 71d.

The refrigerant flowing out from the relay units 4a, 4b, 4c, and 4d is the second branch pipes 5aa, 5bb, 5cc, and 5dd (the relay units 4a, 4b, 4c, 4d and the indoor units 3a, 3b of the liquid refrigerant communication pipes 5). It is sent to the indoor units 3a, 3b, 3c, and 3d through the portion connecting 3c and 3d). The refrigerant sent to the indoor units 3a, 3b, 3c and 3d is decompressed by the indoor expansion valves 51a, 51b, 51c and 51d, and then sent to the indoor heat exchangers 52a, 52b, 52a and 52b. The refrigerant sent to the indoor heat exchangers 52a, 52b, 52c, 52d is sent from the room by the indoor fans 55a, 55b, 55c, 55d in the indoor heat exchangers 52a, 52b, 52c, 52d, which function as a refrigerant evaporator. It evaporates by being heated by exchanging heat with the supplied indoor air. This refrigerant flows out from the indoor units 3a, 3b, 3c, and 3d. On the other hand, the indoor air cooled by the indoor heat exchangers 52a, 52b, 52c and 52d is sent into the room, thereby cooling the room.

The refrigerant flowing out from the indoor units 3a, 3b, 3c and 3d is sent to the relay units 4a, 4b, 4c and 4d through the branch pipes 6a, 6b, 6c and 6d of the gas refrigerant connecting pipe 6. The refrigerant sent to the relay units 4a, 4b, 4c, and 4d passes through the high-pressure gas relay shutoff valves 66a, 66b, 66c, 66d and the low-pressure gas relay shutoff valves 67a, 67b, 67c, 67d, and the relay units 4a, 4b, 4c. It flows out from 4d.

The refrigerant flowing out from the relay units 4a, 4b, 4c, and 4d is the high-low pressure gas refrigerant connecting pipe 7 (merging pipe and branch pipes 7a, 7b, 7c, 7d) and the low-pressure gas refrigerant connecting pipe 8 (merging pipe and branch pipe). It joins the outdoor unit 2 and is sent through the branch pipe portions 8a, 8b, 8c, 8d). The refrigerant sent to the outdoor unit 2 is sucked into the compressor 21 through the gas side closing valves 28a and 28b, the third switching mechanism 22c and the accumulator 29.

<Full heating operation>
During the full heating operation, for example, all of the indoor units 3a, 3b, 3c, and 3d are in the heating operation (that is, all of the indoor heat exchangers 52a, 52b, 52c, and 52d function as refrigerant radiators, and the outdoors. When the heat exchangers 23a and 23b function as a refrigerant evaporator), the switching mechanisms 22a and 22b are switched to the outdoor evaporation state (the state shown by the broken lines of the switching mechanisms 22a and 22b in FIG. 1). Then, the compressor 21, the outdoor fan 24, and the indoor fans 55a, 55b, 55c, 55d are driven. Further, the third switching mechanism 22c is switched to the refrigerant derivation state (the state shown by the broken line of the switching mechanism 22c in FIG. 1), and the liquid relay shutoff valves 71a, 71b, 71c of the relay units 4a, 4b, 4c, and 4d, The 71d and the high-pressure gas relay shutoff valves 66a, 66b, 66c, 66d are opened, and the low-pressure gas relay shutoff valves 67a, 67b, 67c, 67d are closed.

Then, the high-pressure refrigerant discharged from the compressor 21 flows out from the outdoor unit 2 through the third switching mechanism 22c and the gas side closing valve 28a.

The refrigerant flowing out from the outdoor unit 2 branches to the relay units 4a, 4b, 4c, and 4d through the gas refrigerant connecting pipe 6 (the merging pipe portion and the branch pipe portion 7a, 7b, 7c, 7d of the high and low pressure gas refrigerant connecting pipe 7). Will be sent. The refrigerant sent to the relay units 4a, 4b, 4c, and 4d flows out from the relay units 4a, 4b, 4c, and 4d through the high-pressure gas relay shutoff valves 66a, 66b, 66c, and 66d.

The refrigerant flowing out from the relay units 4a, 4b, 4c, and 4d is the branch pipes 6a, 6b, 6c, 6d (of the gas refrigerant connecting pipes 6, the relay units 4a, 4b, 4c, 4d and the indoor units 3a, 3b, 3c. It is sent to the indoor units 3a, 3b, 3c, and 3d through the portion connecting with 3d). The refrigerant sent to the indoor units 3a, 3b, 3c and 3d is sent to the indoor heat exchangers 52a, 52b, 52c and 52d. The high-pressure refrigerant sent to the indoor heat exchangers 52a, 52b, 52c, 52d is used by the indoor fans 55a, 55b, 55c, 55d in the indoor heat exchangers 52a, 52b, 52c, 52d, which function as a radiator of the refrigerant. It condenses by being cooled by exchanging heat with the indoor air supplied from the room. This refrigerant is depressurized by the indoor expansion valves 51a, 51b, 51c, 51d, and then flows out from the indoor units 3a, 3b, 3c, and 3d. On the other hand, the indoor air heated by the indoor heat exchangers 52a, 52b, 52c and 52d is sent into the room, thereby heating the room.

The refrigerant flowing out from the indoor units 3a, 3b, 3c, and 3d is the second branch pipe portion 5aa, 5bb, 5cc, 5dd (relay units 4a, 4b, 4c, 4d and the indoor units 3a, 3b of the liquid refrigerant connecting pipes 5). It is sent to the relay units 4a, 4b, 4c, and 4d through the portion connecting 3c and 3d). The refrigerant sent to the relay units 4a, 4b, 4c, and 4d flows out from the relay units 4a, 4b, 4c, and 4d through the liquid relay shutoff valves 71a, 71b, 71c, and 71d.

The refrigerant flowing out from the relay units 4a, 4b, 4c, and 4d joins the outdoor unit 2 through the liquid refrigerant connecting pipe 5 (merging pipe portion and first branch pipe portion 5a, 5b, 5c, 5d) and is sent. The refrigerant sent to the outdoor unit 2 is sent to the outdoor expansion valves 25a and 25b through the liquid side closing valve 27 and the refrigerant cooler 45. The refrigerant sent to the outdoor expansion valves 25a and 25b is decompressed by the outdoor expansion valves 25a and 25b, and then sent to the outdoor heat exchangers 23a and 23b. The refrigerant sent to the outdoor heat exchangers 23a and 23b evaporates by being heated by exchanging heat with the outdoor air supplied by the outdoor fan 24. This refrigerant is sucked into the compressor 21 through the switching mechanisms 22a and 22b and the accumulator 29.

<Cooling-based operation>
During the cooling-based operation, for example, the indoor units 3b, 3c, and 3d are in the cooling operation, and the indoor unit 3a is in the heating operation (that is, the indoor heat exchangers 52b, 52c, and 52d function as refrigerant evaporators. When the indoor heat exchanger 52a functions as a refrigerant radiator) and the indoor heat exchangers 23a and 23b function as a refrigerant radiator, the switching mechanisms 22a and 22b are in an outdoor heat dissipation state (FIG. FIG. The compressor 21, the outdoor fan 24, and the indoor fans 55a, 55b, 55c, 55d are driven by being switched to the state shown by the solid line of the switching mechanisms 22a and 22b of 1. Further, the third switching mechanism 22c is switched to the refrigerant derivation state (the state shown by the broken line of the switching mechanism 22c in FIG. 1), and the liquid relay shutoff valve 71a, the high pressure gas relay shutoff valve 66a and the relay unit 4b of the relay unit 4a are switched. The liquid relay shutoff valves 71b, 71c, 71d and the low pressure gas relay shutoff valves 67b, 67c, 67d of 4c and 4d are opened, and the low pressure gas relay shutoff valves 67a and the relay units 4b, 4c and 4d of the relay unit 4a are opened. The high-pressure gas relay shutoff valves 66b, 66c, 66d are closed.

Then, a part of the high-pressure refrigerant discharged from the compressor 21 is sent to the outdoor heat exchangers 23a and 23b through the switching mechanisms 22a and 22b, and the rest is sent to the outdoor unit through the third switching mechanism 22c and the gas side closing valve 28a. Outflow from 2. The refrigerant sent to the outdoor heat exchangers 23a and 23b is cooled by exchanging heat with the outdoor air supplied by the outdoor fan 24 in the outdoor heat exchangers 23a and 23b that function as a radiator of the refrigerant. Condensate. This refrigerant flows out from the outdoor unit 2 through the outdoor expansion valves 25a and 25b, the refrigerant cooler 45, and the liquid side closing valve 27. At this time, in the refrigerant cooler 45, the refrigerant flowing out of the outdoor unit 2 is cooled by the refrigerant flowing through the refrigerant return pipe 41.

The refrigerant flowing out of the outdoor unit 2 through the third switching mechanism 22c or the like is sent to the relay unit 4a through the gas refrigerant connecting pipe 6 (the merging pipe portion and the branch pipe portion 7a of the high / low pressure gas refrigerant connecting pipe 7). The refrigerant sent to the relay unit 4a flows out from the relay unit 4a through the high-pressure gas relay shutoff valve 66a.

The refrigerant flowing out from the relay unit 4a is sent to the indoor unit 3a through the branch pipe portion 6a (the portion of the gas refrigerant connecting pipe 6 that connects the relay unit 4a and the indoor unit 3a). The refrigerant sent to the indoor unit 3a is sent to the indoor heat exchanger 52a. The high-pressure refrigerant sent to the indoor heat exchanger 52a is cooled by exchanging heat with the indoor air supplied from the room by the indoor fan 55a in the indoor heat exchanger 52a that functions as a radiator of the refrigerant. Condensate. This refrigerant is depressurized by the indoor expansion valve 51a and then flows out from the indoor unit 3a. On the other hand, the indoor air heated by the indoor heat exchanger 52a is sent into the room, thereby heating the room.

The refrigerant flowing out of the indoor unit 3a is sent to the relay unit 4a through the second branch pipe portion 5aa (the portion of the liquid refrigerant connecting pipe 5 that connects the relay unit 4a and the indoor unit 3a). The refrigerant sent to the relay unit 4a flows out from the relay unit 4a through the liquid relay shutoff valve 71a.

The refrigerant flowing out from the relay unit 4a is sent to the merging pipe portion of the liquid refrigerant connecting pipe 5 through the first branch pipe portion 5a, and merges with the refrigerant flowing out from the outdoor unit 2 through the outdoor heat exchangers 23a, 23b and the like. This refrigerant is branched and sent to the relay units 4b, 4c, and 4d through the first branch pipe portions 5b, 5c, and 5d of the liquid refrigerant communication pipe 5. The refrigerant sent to the relay units 4b, 4c and 4d flows out from the relay units 4b, 4c and 4d through the liquid relay shutoff valves 71b, 71c and 71d.

The refrigerant flowing out from the relay units 4b, 4c, and 4d connects the relay units 4b, 4c, and 4d of the liquid refrigerant connecting pipe 5 with the indoor units 3b, 3c, and 3d. It is sent to the indoor units 3b, 3c and 3d through the part). The refrigerant sent to the indoor units 3b, 3c and 3d is decompressed by the indoor expansion valves 51b, 51c and 51d, and then sent to the indoor heat exchangers 52b, 52a and 52b. The refrigerant sent to the indoor heat exchangers 52b, 52c, 52d is combined with the indoor air supplied from the room by the indoor fans 55b, 55c, 55d in the indoor heat exchangers 52b, 52c, 52d, which function as refrigerant evaporators. Evaporates by heat exchange and heating. This refrigerant flows out from the indoor units 3b, 3c, and 3d. On the other hand, the indoor air cooled by the indoor heat exchangers 52b, 52c and 52d is sent into the room, thereby cooling the room.

The refrigerant flowing out from the indoor units 3b, 3c and 3d is sent to the relay units 4b, 4c and 4d through the branch pipes 6b, 6c and 6d of the gas refrigerant connecting pipe 6. The refrigerant sent to the relay units 4b, 4c and 4d flows out from the relay units 4b, 4c and 4d through the low-pressure gas relay shutoff valves 67b, 67c and 67d.

The refrigerant flowing out from the relay units 4b, 4c, and 4d joins the outdoor unit 2 through the low-pressure gas refrigerant connecting pipe 8 (merging pipe portion and branch pipe portion 8b, 8c, 8d) and is sent. The refrigerant sent to the outdoor unit 2 is sucked into the compressor 21 through the gas side closing valves 28a and 28b, the third switching mechanism 22c and the accumulator 29.

<Heating-based operation>
During the main heating operation, for example, the indoor units 3b, 3c, and 3d are in the heating operation, and the indoor unit 3a is in the cooling operation (that is, the indoor heat exchangers 52b, 52c, and 52d function as refrigerant radiators. When the indoor heat exchanger 52a functions as a refrigerant evaporator) and the indoor heat exchangers 23a and 23b function as a refrigerant evaporator, the switching mechanisms 22a and 22b are in an outdoor evaporation state (FIG. The compressor 21, the outdoor fan 24, and the indoor fans 55a, 55b, 55c, 55d are driven by being switched to the state shown by the solid line of the switching mechanisms 22a and 22b of 1. Further, the third switching mechanism 22c is switched to the refrigerant derivation state (the state shown by the broken line of the switching mechanism 22c in FIG. 1), and the high pressure gas relay shutoff valve 66a of the relay unit 4a and the low pressure of the relay units 4b, 4c and 4d The gas relay shutoff valves 67b, 67c, 67d are closed, and the liquid relay shutoff valves 71a of the relay unit 4a, the low pressure gas relay shutoff valve 67a, and the liquid relay shutoff valves 71b, 71c, 71d of the relay units 4b, 4c, 4d, The high-pressure gas relay shutoff valves 66b, 66c, 66d are opened.

Then, the high-pressure refrigerant discharged from the compressor 21 flows out from the outdoor unit 2 through the third switching mechanism 22c and the gas side closing valve 28a.

The refrigerant flowing out from the outdoor unit 2 is branched and sent to the relay units 4b, 4c, and 4d through the gas refrigerant connecting pipe 6 (the merging pipe portion and the branch pipe portion 7b, 7c, 7d of the high-pressure gas refrigerant connecting pipe 7). .. The refrigerant sent to the relay units 4b, 4c and 4d flows out from the relay units 4b, 4c and 4d through the high-pressure gas relay shutoff valves 66b, 66c and 66d.

The refrigerant flowing out from the relay units 4b, 4c, and 4d is the branch pipes 6b, 6c, and 6d (the portion of the gas refrigerant connecting pipe 6 that connects the relay units 4b, 4c, 4d and the indoor units 3b, 3c, and 3d). It is sent to the indoor units 3b, 3c, and 3d through. The refrigerant sent to the indoor units 3b, 3c and 3d is sent to the indoor heat exchangers 52b, 52c and 52d. The high-pressure refrigerant sent to the indoor heat exchangers 52b, 52c, 52d is supplied from the room by the indoor fans 55b, 55c, 55d in the indoor heat exchangers 52b, 52c, 52d, which function as a radiator of the refrigerant. It condenses by exchanging heat with air and cooling. This refrigerant is depressurized by the indoor expansion valves 51b, 51c, 51d, and then flows out from the indoor units 3b, 3c, and 3d. On the other hand, the indoor air heated by the indoor heat exchangers 52b, 52c and 52d is sent into the room, thereby heating the room.

The refrigerant flowing out from the indoor units 3b, 3c and 3d connects the relay units 4b, 4c and 4d of the liquid refrigerant connecting pipe 5 with the indoor units 3b, 3c and 3d. It is sent to the relay units 4b, 4c, and 4d through the part). The refrigerant sent to the relay units 4b, 4c and 4d flows out from the relay units 4b, 4c and 4d through the liquid relay shutoff valves 71b, 71c and 71d.

The refrigerant flowing out from the relay units 4a, 4b, 4c, and 4d joins the merging pipe portion through the first branch pipe portion 5b, 5c, and 5d of the liquid refrigerant connecting pipe 5, and a part thereof branches to the first branch pipe portion 5a. Then, it is sent to the relay unit 4a, and the rest is sent to the outdoor unit 2 through the merging pipe portion of the liquid refrigerant connecting pipe 5.

The refrigerant sent to the relay unit 4a flows out from the relay unit 4a through the liquid relay shutoff valve 71a.

The refrigerant flowing out from the relay unit 4a is sent to the indoor unit 3a through the second branch pipe portion 5aa (the portion of the liquid refrigerant connecting pipe 5 that connects the relay unit 4a and the indoor unit 3a). The refrigerant sent to the indoor unit 3a is decompressed by the indoor expansion valve 51a and then sent to the indoor heat exchanger 52a. The refrigerant sent to the indoor heat exchanger 52a evaporates by being heated by exchanging heat with the indoor air supplied from the room by the indoor fan 55a in the indoor heat exchanger 52a that functions as a refrigerant evaporator. .. This refrigerant flows out from the indoor unit 3a. On the other hand, the indoor air cooled by the indoor heat exchanger 52a is sent into the room, thereby cooling the room.

The refrigerant flowing out of the indoor unit 3a is sent to the relay unit 4a through the branch pipe portion 6a of the gas refrigerant connecting pipe 6. The refrigerant sent to the relay unit 4a flows out from the relay unit 4a through the low-pressure gas relay shutoff valve 67a.

The refrigerant flowing out of the relay unit 4a is sent to the outdoor unit 2 through the low-pressure gas refrigerant connecting pipe 8 (merging pipe portion and branch pipe portion 8a).

The refrigerant sent to the outdoor unit 2 through the merging pipe portion of the liquid refrigerant connecting pipe 5 is sent to the outdoor expansion valves 25a and 25b through the liquid side closing valve 27 and the refrigerant cooler 45. The refrigerant sent to the outdoor expansion valves 25a and 25b is decompressed by the outdoor expansion valves 25a and 25b, and then sent to the outdoor heat exchangers 23a and 23b. The refrigerant sent to the outdoor heat exchangers 23a and 23b evaporates by being heated by exchanging heat with the outdoor air supplied by the outdoor fan 24. This refrigerant merges with the refrigerant sent to the outdoor unit 2 through the low-pressure gas refrigerant connecting pipe 8 through the switching mechanisms 22a and 22b and the accumulator 29, and is sucked into the compressor 21.

(3) Operation and Features of Air Conditioning Device at Refrigerant Leakage Next, the operation and features of the air conditioner 1 at the time of refrigerant leakage will be described with reference to FIGS. 1 and 2. The operation of the air conditioner 1 at the time of refrigerant leakage described below is the same as the above basic operation, that is, the air conditioner 1 (outdoor unit 2, indoor unit 3a, 3b, 3c, 3d and relay unit 4a, 4b). This is performed by the control unit 19 that controls the constituent devices of 4c and 4d).

In the air conditioner 1, as described above, the relay shutoff valves 71a, 71b, 71c, 71d, 66a are connected to the relay units 4a, 4b, 4c, and 4d together with the refrigerant sensors 79a, 79b, 79c, 79d as the refrigerant leakage detecting means. , 66b, 66c, 66d, 67a, 67b, 67c, 67d are provided. Therefore, by utilizing these configurations, when the refrigerant sensors 79a, 79b, 79c, 79d detect the leakage of the refrigerant, the liquid relay shutoff valves 71a, 71b, 71c, 71d and the gas relay shutoff valves 66a, 66b, It is conceivable to close 66c, 66d, 67a, 67b, 67c, 67d. That is, when the refrigerant leaks, the liquid relay shutoff valves 71a, 71b, 71c, 71d including the indoor units 3a, 3b, 3c, and 3d and the gas relay shutoff valves 66a, 66b, 66c, 66d, 67a, 67b, 67c, 67d. It is conceivable to separate the part between and. As a result, the parts where the refrigerant leaks are the liquid relay shutoff valves 71a, 71b, 71c, 71d including the indoor units 3a, 3b, 3c, and 3d, and the gas relay shutoff valves 66a, 66b, 66c, 66d, 67a, 67b. It is limited to the part between 67c and 67d.

However, closing the liquid relay shutoff valves 71a, 71b, 71c, 71d and the gas relay shutoff valves 66a, 66b, 66c, 66d, 67a, 67b, 67c, 67d includes the indoor units 3a, 3b, 3c, and 3d. It means that the leakage of the refrigerant existing in the portion between the liquid relay shutoff valves 71a, 71b, 71c, 71d and the gas relay shutoff valves 66a, 66b, 66c, 66d, 67a, 67b, 67c, 67d is allowed. .. Therefore, it cannot be said that it is sufficient from the viewpoint of reducing the amount of leakage.

Therefore, here, as shown in FIG. 2, when the refrigerant sensors 79a, 79b, 79c, 79d detect the leakage of the refrigerant, that is, when the refrigerant leaks (step ST1), the refrigerant sensor 79a , 79b, 79c, 79d, and the first cutoff control shown in step ST4 is performed. Here, in the first shutoff control, the step liquid relay shutoff valves 71a, 71b, 71c, 71d are opened, and the indoor expansion valves 51a, 51b, 51c, 51d and the gas relay shutoff valves 66a, 66b, 66c, 66d, 67a, This is a control for closing 67b, 67c, and 67d.

Here, as described above, when the refrigerant leaks, the liquid relay shutoff valves 71a, 71b, 71c, 71d are opened, and the 51a, 51b, 51c, 51d and the gas relay shutoff valves 66a, 66b are controlled by the first shutoff control. , 66c, 66d, 67a, 67b, 67c, 67d are closed. Therefore, the indoor expansion valves 51a, 51b, 51c, 51d including the indoor heat exchangers 52a, 52b, 52c, 52d and the gas relay shutoff valves 66a, 66b, 66c, 66d, 67a, which have a high possibility of refrigerant leakage, Only the portion between 67b, 67c and 67d can be separated. As a result, the portion where the refrigerant leaks is the indoor expansion valves 51a, 51b, 51c, 51d including the indoor heat exchangers 52a, 52b, 52c, 52d and the gas relay shutoff valves 66a, 66b, 66c, 66d, 67a, 67b. , 67c, 67d. This is compared with the case where the liquid relay shutoff valves 71a, 71b, 71c, 71d and the gas relay shutoff valves 66a, 66b, 66c, 66d, 67a, 67b, 67c, 67d are closed when the refrigerant leaks. This means that the portion where the refrigerant leaks can be narrowed while including the indoor heat exchangers 52a, 52b, 52c, and 52d, which are highly likely.

As described above, here, the indoor expansion valves 51a, 51b including the indoor heat exchangers 52a, 52b, 52c, 52d, which have a high possibility of refrigerant leakage by performing the first shutoff control when the refrigerant leaks, Since only the narrow portion between the 51c and 51d and the gas relay shutoff valves 66a, 66b, 66c, 66d, 67a, 67b, 67c and 67d can be separated, the amount of refrigerant leakage can be reduced.

Further, here, as shown in FIG. 2, when the leakage of the refrigerant is detected in step ST1, the control unit 19 issues an alarm (step ST2), and controls before performing the first shutoff control. By stopping the compressor 21 (step ST3), the unit 19 suppresses an excessive increase in the pressure of the refrigerant.

The process of step ST2 is not limited to that performed prior to the process of step ST4, and may be performed at the same time as the process of step ST4, or may be performed after the process of step ST4 is performed. good. Further, the processing of step ST3 is not limited to the one performed prior to the processing of step ST4, and if it is allowed that the pressure of the refrigerant rises to some extent, it is performed at the same time as the processing of step ST4 or immediately after the processing of step ST4. You may try to do it.

(4) Modification 1
In the operation of the air conditioner 1 when the refrigerant leaks in the above embodiment (see FIG. 2), the liquid relay shutoff valves 71a, 71b, 71c, and 71d are opened during the first shutoff control.

At this time, the leakage of the refrigerant is in the vicinity of the indoor heat exchangers 52a, 52b, 52c, 52d (indoor expansion valves 51a, 51b, 51c, 51d including the indoor heat exchangers 52a, 52b, 52c, 52d and the gas relay shutoff valve. It is most likely to originate from (the portion between 66a, 66b, 66c, 66d, 67a, 67b, 67c, 67d). However, although the possibility of refrigerant leakage is lower than that of this portion, there is a possibility that it may also occur from a portion between the liquid relay shutoff valves 71a, 71b, 71c, 71d and the indoor expansion valves 51a, 51b, 51c, 51d. be. Therefore, the indoor expansion valves 51a, 51b, 51c, 51d including the indoor heat exchangers 52a, 52b, 52c, 52d and the gas relay shutoff valves 66a, 66b, 66c, 66d, 67a, 67b, 67c are controlled by the first shutoff control. Even when only the portion between the liquid relay shutoff valves 71a, 71b, 71c, 71d and the indoor expansion valves 51a, 51b, 51c, 51d is separated, it is assumed that the refrigerant leaks from the portion between the liquid relay shutoff valves 71a, 71b, 71c, 71d and the indoor expansion valves 51a, 51b, 51c, 51d. Is preferable. That is, during the first shutoff control, the inflow of the refrigerant from the outdoor unit 2 side to the portion between the liquid relay shutoff valves 71a, 71b, 71c, 71d and the indoor expansion valves 51a, 51b, 51c, 51d is reduced. Is preferable.

Therefore, here, as shown in FIG. 3, the control unit 19 slightly opens the liquid relay shutoff valves 71a, 71b, 71c, 71d composed of the electric expansion valves during the first shutoff control in step ST4, and the outdoor unit. The inflow of the refrigerant from the second side into the portion between the liquid relay shutoff valves 71a, 71b, 71c, 71d and the indoor expansion valves 51a, 51b, 51c, 51d is reduced. Here, "slightly open" is an opening degree of about 15% or less when the fully open liquid relay shutoff valves 71a, 71b, 71c, and 71d are expressed as 100%.

As a result, here, even when the refrigerant leaks from the portion between the liquid relay shutoff valves 71a, 71b, 71c, 71d and the indoor expansion valves 51a, 51b, 51c, 51d, the first During the cutoff control, the leakage of the refrigerant from this portion can be suppressed as much as possible. From the viewpoint of suppressing the leakage of the refrigerant as much as possible, it is conceivable to fully close the liquid relay shutoff valves 71a, 71b, 71c, and 71d. However, when the liquid relay shutoff valves 71a, 71b, 71c, 71d are fully closed, for example, when the leakage of the refrigerant is erroneously detected, the liquid relay shutoff valves 71a, 71b, 71c, 71d and the indoor expansion valves 51a, 51b , 51c, 51d, and liquid sealing will occur in the portion between the, 51c, and 51d, which is not preferable. On the other hand, here, since the liquid relay shutoff valves 71a, 71b, 71c, and 71d are slightly opened, it is possible to suppress the occurrence of liquid sealing in this portion.

(5) Modification example 2
In the operation of the air conditioner 1 when the refrigerant leaks in the above embodiment and the first modification (see FIGS. 2 and 3), the indoor expansion valve including the indoor heat exchangers 52a, 52b, 52c, and 52d is controlled by the first shutoff. Only the portion between the 51a, 51b, 51c, 51d and the gas relay shutoff valves 66a, 66b, 66c, 66d, 67a, 67b, 67c, 67d is separated.

However, if the refrigerant continues to leak even after the first shutoff control, the refrigerant leaks between the liquid relay shutoff valves 71a, 71b, 71c, 71d and the indoor expansion valves 51a, 51b, 51c, 51d. It may be generated from a part.

Therefore, here, as shown in FIG. 4 or 5, when the control unit 19 determines that the leakage of the refrigerant continues even if the first shutoff control in step ST4 is performed, it is shown in step ST6. The second cutoff control is performed. The second shutoff control is a control for closing the liquid relay shutoff valves 71a, 71b, 71c, 71d while keeping the indoor expansion valves 51a, 51b, 51c, 51d closed, whereby the liquid relay shutoff valves 71a, 71b, The portion between the 71c and 71d and the indoor expansion valves 51a, 51b, 51c and 51d is separated.

As a result, here, when the refrigerant leaks, the liquid relay shutoff valves 71a, 71b, 71c, 71d and the indoor expansion valve 51a are performed by performing the second shutoff control in step ST6 following the first shutoff control in step ST4. The portion between the 51b, 51c, and 51d can be separated, and the amount of refrigerant leakage can be reduced.

Further, in step ST5, the control unit 19 determines whether or not the leakage of the refrigerant continues even after the first cutoff control in step ST4 is performed. In this step ST5, the control unit 19 performs the first shutoff control based on the temperature Trl of the refrigerant detected by the indoor heat exchange liquid side sensors 57a, 57b, 57c, 57d during the first shutoff control of step ST4. However, it is determined whether or not the refrigerant leakage continues. Specifically, the vicinity of the indoor heat exchangers 52a, 52b, 52c, 52d (indoor expansion valves 51a, 51b, 51c, 51d including the indoor heat exchangers 52a, 52b, 52c, 52d and the gas relay shutoff valves 66a, 66b , 66c, 66d, 67a, 67b, 67c, 67d), the change tendency of the temperature Trl of the refrigerant when the leakage of the refrigerant occurs is used to determine whether or not the leakage of the refrigerant continues. .. For example, if the refrigerant leaks in the vicinity of the indoor heat exchangers 52a, 52b, 52c, 52d when the first cutoff control in step ST4 is performed, the refrigerant leaks in the vicinity of the indoor heat exchangers 52a, 52b, 52c, 52d. Compared with the case where no leakage has occurred, the temperature of the refrigerant (here, Trl) in the vicinity of the indoor heat exchangers 52a, 52b, 52c, and 52d tends to change abruptly due to the leakage of the refrigerant. Further, due to the leakage of the refrigerant, the temperature of the refrigerant near the indoor heat exchangers 52a, 52b, 52c, 52d (here, Trl) is set to the ambient temperature at which the indoor heat exchangers 52a, 52b, 52c, 52d are arranged (for example,). There is a tendency to quickly approach the temperature Tra of the indoor air detected by the indoor air sensors 59a, 59b, 59c, 59d, etc.). Therefore, for example, when the rate of change ΔTrl of the temperature Trl of the refrigerant becomes larger than the predetermined rate of change ΔTrls, or when the temperature Trl of the refrigerant reaches the predetermined temperature Tras determined by the atmospheric temperature Tra within a predetermined time ts. It can be said that the refrigerant leaks in the vicinity of the indoor heat exchangers 52a, 52b, 52c and 52d. On the other hand, when the rate of change ΔTrl of the temperature Trl of the refrigerant becomes equal to or less than the predetermined rate of change ΔTrls, or when the temperature Trl of the refrigerant does not reach the predetermined temperature Tras determined by the ambient temperature Tra within a predetermined time ts. It can be determined that the refrigerant does not leak in the vicinity of the indoor heat exchangers 52a, 52b, 52c, and 52d, that is, the refrigerant continues to leak even if the first shutoff control is performed.

Thereby, here, the control unit 19 can appropriately determine whether or not the leakage of the refrigerant continues even if the first shutoff control is performed in step ST5.

The temperature of the refrigerant used for the determination in step ST5 is not limited to the temperature Trl of the refrigerant detected by the indoor heat exchange liquid side sensors 57a, 57b, 57c, 57d, and the indoor heat exchange gas side sensor. The temperature Trg of the refrigerant at the gas side ends of the indoor heat exchangers 52a, 52b, 52c, 52d detected by 58a, 58b, 58c, 58d may be used.

Further, in step ST5, when it is determined that the refrigerant continues to leak even if the first cutoff control is performed, the vicinity of the indoor heat exchangers 52a, 52b, 52c, 52d (indoor heat exchangers 52a, 52b). , 52c, 52d and the indoor expansion valves 51a, 51b, 51c, 51d and the gas relay shutoff valves 66a, 66b, 66c, 66d, 67a, 67b, 67c, 67d). It is highly possible that it has not been done.

Therefore, here, in step ST6, the control unit 19 opens the gas relay shutoff valves 66a, 66b, 66c, 66d, 67a, 67b, 67c, 67d at the time of the second shutoff control.

As a result, here, in step ST6, the portion between the indoor expansion valves 51a, 51b, 51c, 51d and the gas relay shutoff valves 66a, 66b, 66c, 66d, 67a, 67b, 67c, 67d is separated. It can be released so that only the portion between the liquid relay shutoff valves 71a, 71b, 71c, 71d and the indoor expansion valves 51a, 51b, 51c, 51d is separated.

In this modification as well, the process of step ST2 is not limited to the process performed prior to the process of steps ST4 to ST6, and may be performed at the same time as any of the processes of steps ST4 to ST6. It may be performed after performing some of the processes of ST4 to ST6. Further, the processing of step ST3 is not limited to the one performed prior to the processing of step ST4, and if it is allowed that the pressure of the refrigerant rises to some extent, it is performed at the same time as the processing of step ST4 or immediately after the processing of step ST4. You may try to do it.

(6) Modification 3
In the operation of the air conditioner 1 when the refrigerant leaks in the second modification (see FIGS. 4 and 5), the gas relay shutoff valves 66a, 66b, 66c, 66d, 67a, 67b, 67c, 67d are performed during the second shutoff control. I try to open it.

At this time, even if it is determined that the refrigerant continues to leak even if the first cutoff control is performed, the vicinity of the indoor heat exchangers 52a, 52b, 52c, 52d (indoor heat exchangers 52a, 52b, 52c, Refrigerant leakage may occur in the indoor expansion valves 51a, 51b, 51c, 51d including 52d and the gas relay shutoff valves 66a, 66b, 66c, 66d, 67a, 67b, 67c, 67d). Sex cannot be completely denied. Therefore, even when only the portion between the liquid relay shutoff valves 71a, 71b, 71c, 71d and the indoor expansion valves 51a, 51b, 51c, 51d is separated by the second shutoff control, the indoor expansion valves 51a, 51b, 51c , 51d and the gas relay shutoff valves 66a, 66b, 66c, 66d, 67a, 67b, 67c, 67d. That is, at the time of the second shutoff control, from the outdoor unit 2 side to the portion between the gas relay shutoff valves 66a, 66b, 66c, 66d, 67a, 67b, 67c, 67d and the indoor expansion valves 51a, 51b, 51c, 51d. It is preferable to reduce the inflow of the refrigerant.

Therefore, here, as shown in FIGS. 6 and 7, when the control unit 19 controls the second shutoff in step ST6, the gas relay shutoff valves 66a, 66b, 66c, 66d, 67a, 67b, which are electric expansion valves, are used. With 67c and 67d slightly opened, from the outdoor unit 2 side to the portion between the gas relay shutoff valves 66a, 66b, 66c, 66d, 67a, 67b, 67c, 67d and the indoor expansion valves 51a, 51b, 51c, 51d. The inflow of the refrigerant is reduced. Here, "slightly open" is an opening degree of about 15% or less when the fully open gas relay shutoff valves 66a, 66b, 66c, 66d, 67a, 67b, 67c, and 67d are expressed as 100%.

As a result, here, the refrigerant leaks from the portion between the indoor expansion valves 51a, 51b, 51c, 51d and the gas relay shutoff valves 66a, 66b, 66c, 66d, 67a, 67b, 67c, 67d. Even in this case, the leakage of the refrigerant from this portion can be suppressed as much as possible during the second cutoff control.

(7) Other modified examples <A>
In the air conditioner 1 of the above-described embodiments and modifications 1 to 3, relay units 4a, 4b, 4c, and 4d corresponding to the indoor units 3a, 3b, 3c, and 3d are provided, but the present invention is limited to these. For example, it may be a relay unit in which all of the relay units 4a, 4b, 4c, and 4d, or some of the relay units 4a, 4b, 4c, and 4d are collectively configured.

<B>
In the air conditioner 1 of the above embodiment (see FIG. 2) and modification 2 (see only the case shown in FIG. 4), the liquid relay shutoff valves 71a, 71b, 71c, 71d and the gas relay shutoff valves 66a, 66b, 66c, The 66d, 67a, 67b, 67c, and 67d may not be electric expansion valves but solenoid valves that can be opened and closed. Further, in the air conditioner 1 of the above modification 1 (see FIG. 3) and the air conditioner 1 of the modification 2 (see only the case shown in FIG. 5), the gas relay shutoff valves 66a, 66b, 66c, 66d, 67a, The 67b, 67c, and 67d may not be electric expansion valves but solenoid valves that can be opened and closed. Further, in the air conditioner 1 of the above modification 2 (see only the case shown in FIG. 6), the liquid relay shutoff valves 71a, 71b, 71c, and 71d are not electric expansion valves but solenoid valves that can be opened and closed. May be good.

<C>
In the air conditioner 1 of the above-described embodiment and the first to third embodiments, the refrigerant flowing through the indoor units 3a, 3b, 3c, and 3d in the basic operations (total cooling operation, total heating operation, cooling main operation, and heating main operation). The flow rate of the indoor expansion valves 51a, 51b, 51c, 51d is controlled by depressurization, but the flow rate is not limited to this. For example, by utilizing the fact that the liquid relay shutoff valves 71a, 71b, 71c, 71d of each relay unit 4a, 4b, 4c, and 4d are electric expansion valves, the pressure reduction in the indoor expansion valves 51a, 51b, 51c, 51d is replaced. Therefore, the flow rate of the refrigerant flowing through the indoor units 3a, 3b, 3c, and 3d may be controlled by depressurizing the liquid relay shutoff valves 71a, 71b, 71c, and 71d.

<D>
In the air conditioner 1 of the above-described embodiments and modifications 1 to 3, the refrigerant sensors 79a, 79b, 79c, 79d are used as the refrigerant leakage detecting means for detecting the refrigerant leakage, but the present invention is limited to this. For example, the leakage of the refrigerant may be detected from the temperature change of the refrigerant temperature Trl, Trg, the indoor air temperature Tra, etc. near the indoor heat exchangers 52a, 52b, 52c, and 52d.

The present invention relates to an outdoor unit, an outdoor unit, a plurality of indoor units, a liquid-refrigerant connecting pipe and a gas-refrigerant connecting pipe, and a gas connected to a liquid-refrigerant connecting pipe and a gas-refrigerant connecting pipe. It can be widely applied to a relay unit having a relay shutoff valve in a connecting pipe, a refrigerant leak detecting means for detecting a refrigerant leak, and an air conditioner including the refrigerant leak detecting means.

1 Air conditioner 2 Outdoor unit 3a, 3b, 3c, 3d Indoor unit 4a, 4b, 4c, 4d Relay unit 5 Liquid refrigerant communication pipe 6 Gas refrigerant communication pipe 19 Control unit 21 Compressor 51a, 51b, 51c, 51d Indoor expansion Valves 52a, 52b, 52c, 52d Indoor heat exchanger 57a, 57b, 57c, 57d Indoor heat exchange liquid side sensor (temperature sensor)
58a, 58b, 58c, 58d Indoor heat exchange gas side sensor (temperature sensor)
61a, 61b, 61c, 61d Liquid connection pipes 62a, 62b, 62c, 62d Gas connection pipes 66a, 66b, 66c, 66d High-pressure gas relay shutoff valve (gas relay shutoff valve)
67a, 67b, 67c, 67d Low pressure gas relay shutoff valve (gas relay shutoff valve)
71a, 71b, 71c, 71d Liquid relay shutoff valve 79a, 79b, 79c, 79d Refrigerant sensor (refrigerant leakage detection means)

Patent No. 5517789

Claims (5)

An outdoor unit (2) having a compressor (21) and
An indoor unit (3a, 3b, 3c, 3d) having an indoor expansion valve (51a, 51b, 51c, 51d) and an indoor heat exchanger (52a, 52b, 52c, 52d).
A liquid refrigerant connecting pipe (5) and a gas refrigerant connecting pipe (6) connecting the outdoor unit and the indoor unit,
Liquid relay shutoff valves (71a, 71b, 71c,) provided in the liquid-refrigerant connecting pipe and the gas-refrigerant connecting pipe and connected to the liquid-refrigerant connecting pipe (61a, 61b, 61c, 61d) 71d) and a relay having a gas relay shutoff valve (66a, 66b, 66c, 66d, 67a, 67b, 67c, 67d) on a gas connection pipe (62a, 62b, 62c, 62d) connected to the gas refrigerant communication pipe. With the unit
Refrigerant leakage detecting means (79a, 79b, 79c, 79d) for detecting refrigerant leakage, and
A control unit (19) that controls the components of the outdoor unit, the indoor unit, and the relay unit, and
In an air conditioner equipped with
The indoor expansion valve, the liquid relay shutoff valve, and the gas relay shutoff valve are control valves whose opening and closing are controlled by the control unit, respectively.
When the refrigerant leaks, the control unit stops the compressor based on the information of the refrigerant leak detecting means, and performs the first shutoff control.
The first shutoff control opens the liquid relay shutoff valve and closes the indoor expansion valve and the gas relay shutoff valve.
Air conditioner. The air conditioner according to claim 1, wherein the control unit stops the compressor after the first shutoff control. The air conditioner according to claim 1, wherein the control unit stops the compressor before the first shutoff control. When the control unit determines that the leakage of the refrigerant continues even after performing the first shutoff control, the control unit closes the liquid relay shutoff valve while keeping the indoor expansion valve closed. Take control,
The air conditioner according to any one of claims 1 to 3. The indoor unit further includes temperature sensors (57a, 57b, 57c, 57d, 58a, 58b, 58c, 58d) that detect the temperature of the refrigerant in the vicinity of the indoor heat exchanger.
The control unit determines whether or not the leakage of the refrigerant continues even if the first shutoff control is performed, based on the temperature of the refrigerant detected by the temperature sensor during the first shutoff control. Item 4. The air conditioner according to item 4.

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