JP2010169309A - Air conditioner - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce the amount of a refrigerant in a refrigerating cycle and improve cooling capacity without increasing the size of an intermediate unit and cost in an air conditioner. <P>SOLUTION: In the air conditioner, an outdoor unit A is connected to a plurality of indoor units B2a-B2b which have no expansion valves via the intermediate unit C including an expansion valve. The intermediate unit C includes: a bypass pipe C3 for interconnecting refrigerant piping C1 on the outdoor unit side of an intermediate liquid side branch pipe 10b and refrigerant piping C2 on the outdoor unit side of an intermediate gas side branch pipe 14b; the refrigerant cooling expansion valve 12 provided in the bypass piping C3; and a refrigerant cooling heat exchanger 13 performing heat exchange between the bypass pipe C3 and the refrigerant piping C1 on the outdoor unit side of the intermediate liquid side branch pipe 10b. A control device E controls the refrigerant cooling expansion valve 12 to cool a refrigerant of gas-liquid two phases made to flow in from the outdoor unit A side by the refrigerant cooling heat exchanger 13 and make the refrigerant in the state of a liquid single phase flow in to an intermediate expansion valve 15. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an air conditioner including an outdoor unit and a plurality of indoor units, and in particular, air connecting an outdoor unit and a plurality of indoor units having no expansion valve via an intermediate unit having an expansion valve. It is suitable for a harmony machine.

  As this type of conventional air conditioner, there is a multi-room air conditioner disclosed in Japanese Patent Laid-Open No. Hei 2-213039 (Patent Document 1).

  This multi-room air conditioner includes a plurality of indoor units that include an indoor heat exchanger and no indoor expansion valve in one outdoor unit (outdoor unit) that includes a compressor, a four-way valve, and an outdoor heat exchanger. A machine (indoor unit) is connected through a branch unit (intermediate unit). The branch unit is a heat exchange that exchanges heat between the liquid side branch pipe that branches the liquid side pipe into a plurality, the gas side branch pipe that branches the gas side pipe into a plurality, and the liquid side pipe and the gas side pipe. And an expansion valve connected to the liquid side branch pipe.

  In this multi-room air conditioner, the high-temperature and high-pressure refrigerant gas discharged from the compressor during cooling operation is condensed in the outdoor heat exchanger to become high-pressure liquid refrigerant, and branches from the outdoor unit through the liquid-side main connection pipe. Sent to the unit. The liquid refrigerant in the branch unit is subcooled by the heat exchanger in the branch unit, and then decompressed by each expansion valve in the branch unit to become a gas-liquid two-phase refrigerant, and is distributed to each indoor unit through the liquid side branch connection pipe. Is done. Here, the distribution of the refrigerant to each indoor unit is performed by the control means controlling each expansion valve in accordance with the operating state of each indoor unit. The refrigerant distributed to the indoor unit is evaporated in the indoor heat exchanger to become a gas refrigerant, and is sent to the branch unit through the gas side branch connecting pipe. The gas refrigerant that has entered the branch unit is wetted by the heat exchanger in the branch unit, and then sent to the compressor in the outdoor unit through the gas-side main communication pipe. In this multi-room air conditioner, it is possible to connect a plurality of indoor units having no expansion valve to an outdoor unit using a branch unit equipped with an expansion valve.

Japanese Laid-Open Patent Publication No. 2-213039

  However, in the multi-room air conditioner of Patent Document 1 described above, the liquid refrigerant condensed in the outdoor heat exchanger is sent to the branch unit through the liquid-side main connection pipe during the cooling operation, so the amount of refrigerant in the refrigeration cycle There was a problem that a lot was needed.

  Therefore, for the purpose of reducing the amount of refrigerant in the refrigeration cycle, it is conceivable to send the state of gas-liquid two-phase refrigerant from the outdoor unit to the branch unit. Alternatively, when the pipe length from the outdoor unit to the branch unit is long or thin, it is considered that the branch unit is in a gas-liquid two-phase refrigerant state due to pressure loss. In that case, it is necessary to depressurize the gas-liquid two-phase refrigerant with the expansion valve in the branch unit, so it is not possible to cope with the small capacity expansion valve, and a large capacity expansion valve must be applied. It becomes. Along with the increase in the size of the expansion valve, there has been a new problem of increasing the size and cost of the branch unit. Or the subject that the piping length from an outdoor unit to a branch unit had to be controlled short occurred.

  An object of the present invention is to reduce the amount of refrigerant in the refrigeration cycle, improve the cooling capacity, and extend the piping length from the outdoor unit to the branch unit without increasing the size and cost of the intermediate unit. The object is to provide an air conditioner that can be used.

  In order to achieve the above object, in the present invention, an outdoor unit having a compressor and an outdoor heat exchanger, a plurality of indoor units having an indoor heat exchanger and having no indoor expansion valve, and the outdoor unit A liquid side communication pipe and a gas side communication pipe that communicate with the plurality of indoor units, an intermediate liquid side branch pipe that is interposed in the middle of the liquid side connection pipe, and an intermediate that is interposed in the middle of the gas side communication pipe In an air conditioner comprising: a gas side branch pipe; an intermediate unit having an intermediate expansion valve provided in a refrigerant pipe on the indoor unit side of the intermediate liquid side branch pipe; and a control device that controls the intermediate expansion valve. The intermediate unit includes a bypass pipe connecting the refrigerant pipe on the outdoor unit side of the intermediate liquid side branch pipe and the refrigerant pipe on the outdoor unit side of the intermediate gas side branch pipe, and a cooling pipe provided in the bypass pipe. A cooling expansion valve, and a refrigerant cooling heat exchanger that exchanges heat between the bypass pipe and the refrigerant pipe on the outdoor unit side of the intermediate liquid side branch pipe, and the control device, during cooling operation, The refrigerant cooling expansion valve is controlled so that the refrigerant that has become a gas-liquid two-phase flowing from the outdoor unit side is cooled by the refrigerant cooling heat exchanger and flows into the intermediate expansion valve in a liquid single-phase state. It is in the configuration.

A more preferable specific configuration example of the present invention is as follows.
(1) The outdoor unit includes an outdoor expansion valve, and the control device controls the refrigerant flowing out from the outdoor unit side during cooling operation to be in a gas-liquid two-phase.
(2) The intermediate unit includes a plurality of intermediate units connected to the outdoor unit, and each of the intermediate units includes a refrigerant pipe on the outdoor unit side of the intermediate liquid side branch pipe and an outdoor unit of the intermediate gas side branch pipe. When a refrigerant valve on the side is provided with a solenoid valve, the indoor unit is provided with the number of indoor units that can be operated by the operation of the outdoor unit or a total capacity or more, and the control device includes the intermediate unit that is not operated, The refrigerant recovery operation is performed by controlling the solenoid valve so as not to be in an insufficient refrigeration cycle state.

  According to the air conditioner of the present invention, the amount of refrigerant in the refrigeration cycle can be reduced, the cooling capacity can be improved, and the pipe length can be extended without increasing the size and cost of the intermediate unit.

  Hereinafter, a plurality of embodiments of the present invention will be described with reference to the drawings. The same reference numerals in the drawings of the respective embodiments indicate the same or equivalent.

(First embodiment)
The air conditioner of 1st Embodiment of this invention is demonstrated using FIG. FIG. 1 is a refrigeration cycle diagram of an air conditioner according to a first embodiment of the present invention.

  First, the structure of the air conditioner of this embodiment is demonstrated.

  In the air conditioner of the present embodiment, one outdoor unit A, a plurality of indoor units B, one intermediate unit C, and the outdoor unit A, the plurality of indoor units B, and the intermediate unit C are connected. A pipe D and a control device E are provided. One refrigeration cycle system is constituted by the communication pipe D.

  The outdoor unit A includes a compressor 21, a four-way valve 22, an outdoor heat exchanger 23, an outdoor expansion valve 24, an outdoor blower 25, an outdoor gas side blocking valve 1, and an outdoor liquid side blocking valve 2. The compressor 21, the four-way valve 22, the outdoor heat exchanger 23, and the outdoor expansion valve 24 are refrigerant pipes between the outdoor gas side blocking valve 1 and the outdoor liquid side blocking valve 2 so as to constitute a part of the refrigeration cycle. Are connected in order.

  The compressor 21 sucks and compresses the low-temperature and low-pressure gas refrigerant and discharges it as a high-temperature and high-pressure gas refrigerant. The compressor 21 is driven by an inverter and the rotational speed is controlled.

  The four-way valve 22 switches the refrigerant flow in the refrigerant piping on the suction side and discharge side of the compressor 21 to form a cooling cycle and a heating cycle. The cooling cycle is a refrigeration cycle configured during cooling operation, and the refrigerant flows as indicated by solid line arrows in FIG. A heating cycle is a refrigerating cycle comprised at the time of heating operation, and a refrigerant | coolant flows like the broken-line arrow of FIG.

  The outdoor heat exchanger 23 functions as a condenser during the cooling operation, and functions as an evaporator during the heating operation. The outdoor blower 25 sends outdoor air to the outdoor heat exchanger 23 to exchange heat between the outdoor air and the refrigerant flowing through the outdoor heat exchanger 23.

  The indoor unit B is composed of a first group of indoor units B1a to B1b having a built-in indoor expansion valve 5, and a second group of indoor units B2a to B2b having no built-in indoor expansion valve. In the present embodiment, the number of indoor units B1a to B1b in the first group is two, but the number may be other than that, and the number of indoor units B2a to B2b in the second group is two. It may be more than one.

  However, the number or total capacity of the indoor units B is limited to the number or total capacity that the indoor units B can be operated by the operation of the outdoor unit A. By this restriction, it is possible to prevent the indoor heat exchange capacity from being excessive with respect to the outdoor heat exchange capacity, resulting in a cycle balance not being achieved, and a refrigeration cycle state having an insufficient refrigerant amount. In other words, when connecting more than the specified number of indoor units combined with one outdoor unit or more than the specified total capacity, the indoor heat exchange capacity is excessive with respect to the outdoor heat exchange capacity, and cycle balance cannot be achieved. It is because it will be in the refrigerating cycle state with insufficient refrigerant quantity. In this refrigeration cycle state where the amount of refrigerant is insufficient, adverse effects such as insulation deterioration due to insufficient cooling of the motor built in the compressor 21, deterioration of refrigeration oil and refrigerant due to an increase in discharge gas temperature, and reduction in refrigeration capacity due to a decrease in refrigerant circulation amount, etc. Effect. For this reason, if the refrigerant amount is additionally sealed, the refrigeration cycle state in which the refrigerant amount is insufficient is eliminated, but the refrigerant amount becomes excessive with respect to the capacity of the compressor 21 and the capacity of the refrigerant liquid receiving tank and auxiliary equipment. Liquid refrigerant that could not be completely evaporated in the cooler (indoor heat exchanger during cooling, outdoor heat exchanger during heating) is returned to the compressor 21, thereby reducing the viscosity of the refrigerating machine oil and lubricating the compressor 21. Deterioration of reliability such as bearing wear due to defects and failure of the compressor 21 is caused.

  The first group of indoor units B1a to B1b includes an indoor blower 3, an indoor heat exchanger 4, and an indoor expansion valve 5. The outdoor unit A is not connected to the outdoor unit A via the connecting pipe D without the intermediate unit C. It is communicated to.

  The indoor heat exchanger 4 functions as an evaporator during the cooling operation and functions as a condenser during the heating operation. The indoor blower 3 sends room air to the indoor heat exchanger 4 to exchange heat between the room air and the refrigerant flowing through the indoor heat exchanger 4. The indoor expansion valve 5 is controlled by the control device E so as to have a throttling function during the cooling operation and to be fully opened and not have a throttling function during the heating operation.

  The second group of indoor units B2a to B2b includes an indoor blower 3 and an indoor heat exchanger 4, and communicates with the outdoor unit A via a communication pipe D and an intermediate unit C. The indoor units B2a to B2b differ from the first group of indoor units B1a to B1b in that they do not have the indoor expansion valve 5, but are the same as the first group of indoor units B1a to B1b in other basic configurations. is there.

  The connecting pipe D is composed of a liquid side connecting pipe D1 and a gas side connecting pipe D2. A plurality of liquid side branch pipes 7a to 7b are provided in the middle of the liquid side communication pipe D1. The liquid side communication pipe D1 includes a refrigerant pipe D11 extending from the outdoor liquid side blocking valve 2 to the liquid side branch pipe 7a, a refrigerant pipe D12 connecting the liquid side branch pipes 7a to 7b, and each liquid side branch pipe. A refrigerant pipe D131 branched from the first group of indoor units B1a to B1b and a refrigerant pipe D132 branched from the liquid side branch pipe 7b and extended to the second group of indoor units B2a to B2b. ing.

  A plurality of gas side branch pipes 6a to 6b are provided in the middle of the gas side communication pipe D2. The communication pipe D2 includes a refrigerant pipe D21 extending from the outdoor gas side blocking valve 1 to the gas side branch pipe 6a, a refrigerant pipe D22 connecting the gas side branch pipes 6a to 6b, and the gas side branch pipes 6a to 6a. A refrigerant pipe D231 branched from 6b and extending to the first group of indoor units B1a to B1b and a refrigerant pipe D232 branched from the gas side branch pipe 6b and extended to the second group of B2a to B2b.

  The intermediate unit C is provided in the middle of a connecting pipe D that connects the outdoor unit A and the plurality of indoor units B. Specifically, the intermediate unit C is provided in the middle of the refrigerant pipes D132 and D232 connecting the liquid side branch pipe 7b and the gas side branch pipe 6b and the second group of indoor units B2a to B2b. .

  The refrigerant pipe of the intermediate unit C includes a liquid side refrigerant pipe C1 interposed in the middle of the liquid side communication pipe D1 (specifically, refrigerant pipe D132) and a gas side communication pipe D2 (specifically, refrigerant pipe D232). ) And a bypass pipe C3 connecting the liquid side refrigerant pipe C1 and the gas side refrigerant pipe C2.

  In the middle of the liquid side refrigerant pipe C1, an intermediate liquid side branch pipe 10a for branching the bypass circuit and an intermediate liquid side branch pipe 10b for branching the indoor unit are provided. In the middle of the gas side refrigerant pipe C2, an intermediate gas side branch pipe 14a for bypass circuit branching and an intermediate gas side branch pipe 14b for indoor unit branching are provided.

  The liquid side refrigerant pipe C1 includes a refrigerant pipe C11 extending from the outdoor side refrigerant pipe D132 to the intermediate liquid side branch pipe 10a, a refrigerant pipe C12 connecting the intermediate liquid side branch pipes 10a and 10b, and the intermediate liquid side branch pipe 10b. And a refrigerant pipe C13 extending from the second group of indoor units B2a to B2b.

  The gas side refrigerant pipe C2 includes a refrigerant pipe C21 extending from the outdoor side refrigerant pipe D232 to the intermediate gas side branch pipe 14a, a refrigerant pipe C22 connecting the intermediate gas side branch pipes 14a and 14b, and a gas side branch pipe 14b. The refrigerant pipe C23 is branched and extends to the second group of indoor units B2a to B2b.

  A liquid side solenoid valve 9 is provided in the refrigerant pipe C11, and a gas side solenoid valve 8 is provided in the refrigerant pipe C21. Both the liquid side solenoid valve 9 and the gas side solenoid valve 8 are closed when the second group of indoor units B2a to B2b are not used. Each refrigerant pipe C13 is provided with an intermediate expansion valve 15 for an indoor unit.

  The bypass pipe C3 configures a bypass circuit that bypasses the refrigerant pipes C12 and C13, the indoor units B2a and B2b, and the refrigerant pipes C23 and C22 and flows the refrigerant during the cooling operation. A refrigerant cooling heat exchanger 13 for exchanging heat between a part of the bypass pipe C3 and a part of the refrigerant pipe C12 is provided. The bypass pipe C3 is provided with an expansion valve 12 for cooling the refrigerant. The refrigerant cooling expansion valve 12 is located between the intermediate liquid side branch pipe 10 a and the refrigerant cooling heat exchanger 13.

  The control device E controls the gas side solenoid valve 8, the liquid side solenoid valve 9, the refrigerant cooling expansion valve 12, the intermediate expansion valve 15, and the like. In FIG. 1, in order to emphasize the control of the refrigerant cooling expansion valve 12 and the intermediate expansion valve 15, the control device E and the refrigerant cooling expansion valve 12 and the intermediate expansion valve 15 are connected by a dashed line arrow. . Further, the control device E may be arranged in a concentrated manner, or may be distributed in each unit.

  Next, the operation | movement at the time of the cooling operation of the air conditioner of this embodiment is demonstrated. During the cooling operation, the four-way valve 22 is switched so as to constitute a cooling cycle, and the refrigerant flows as indicated by solid line arrows in FIG.

  That is, the gas refrigerant compressed to high temperature and high pressure by the compressor 21 is radiated to the outdoor air by the outdoor heat exchanger 23 to be condensed and converted into liquid refrigerant. This liquid refrigerant is made into a gas-liquid two-phase refrigerant by being slightly decompressed by the outdoor expansion valve 24.

  This gas-liquid two-phase refrigerant flows out from the outdoor liquid side blocking valve 2 to the liquid side communication pipe D1, and is branched by the liquid side branch pipes 7a and 7b to have the indoor units B1a to B1b and the intermediate expansion valve having the indoor expansion valve 5. 15 into the intermediate unit C. Here, since the gas-liquid two-phase refrigerant flows through the refrigerant pipes D11, D12, D131, and D132 that connect the outdoor unit A, the indoor units B1a to B1b, and the intermediate unit C, when the liquid refrigerant of the prior art flows. In comparison, the amount of refrigerant in the refrigeration cycle can be reduced.

  The gas-liquid two-phase refrigerant that has flowed into the indoor units B1a to B1b is depressurized by the indoor expansion valve 5 and is evaporated by absorbing heat from the indoor air (cooling the room) by the indoor heat exchanger 4 to become a gas refrigerant. . This gas refrigerant flows from the outdoor gas side blocking valve 1 into the outdoor unit A through the refrigerant pipes D231, D22, and D21, and flows into the compressor 21 through the four-way valve 22.

  On the other hand, the gas-liquid two-phase refrigerant that has flowed into the intermediate unit C passes through the refrigerant pipe C1 and is branched into the bypass pipe C3 and the refrigerant pipe C12 by the intermediate liquid side branch pipe 10a.

  The gas-liquid two-phase refrigerant branched to the bypass pipe C3 is decompressed by the refrigerant cooling expansion valve 12 to be a low-temperature low-pressure gas-liquid two-phase refrigerant, and then evaporated by the refrigerant cooling heat exchanger 13 to be gas refrigerant. It becomes. This gas refrigerant is merged with refrigerant from the indoor units B2a to B2b in the intermediate gas side branch pipe 14a and returned to the compressor 21.

  The gas-liquid two-phase refrigerant branched to the refrigerant pipe C12 is cooled by the refrigerant cooling heat exchanger 13 to be a liquid single-phase refrigerant. As a result, a larger specific enthalpy difference on the refrigeration cycle can be obtained, so that the cooling capacity can be improved while maintaining a small amount of refrigerant.

  The liquid refrigerant is branched into a plurality of refrigerant pipes C13 by the intermediate liquid side branch pipe 10b, and the pressure is reduced by the intermediate expansion valve 15 provided in each refrigerant pipe C13. Thus, since the intermediate expansion valve 15 depressurizes the liquid refrigerant that flows in, the intermediate expansion valve 15 can be depressurized with a small-capacity expansion valve, and the small-capacity expansion valve can be used even in an indoor unit with a large capacity.

  The gas-liquid two-phase refrigerant decompressed by the intermediate expansion valve 15 is vaporized by absorbing heat from room air (cooling the room) by the indoor heat exchanger 4 and becomes gas refrigerant. This gas refrigerant is merged in the intermediate gas side branch pipe 14b through the refrigerant pipe C23, and further merged with the refrigerant in the bypass pipe C3 in the intermediate gas side branch pipe 14a through the refrigerant pipe C22, and then the refrigerant pipe D232, It flows into the outdoor unit A from the outdoor gas side blocking valve 1 through D22 and D21, and returns to the compressor 21 through the four-way valve 22.

  According to this embodiment, the intermediate unit C includes the refrigerant pipe C1 (C11 or C12) on the outdoor unit side of the intermediate liquid side branch pipe 10b and the refrigerant pipe C2 (C21 or C22) on the outdoor unit side of the intermediate gas side branch pipe 14b. ), A refrigerant cooling expansion valve 12 provided in the bypass pipe C3, and the bypass pipe C3 and the refrigerant pipe C1 (C12) on the outdoor unit side of the intermediate liquid side branch pipe 10b. And the refrigerant cooling heat exchanger 13 that exchanges heat with the refrigerant. The control device E cools the refrigerant that has become a gas-liquid two-phase flowing in from the outdoor unit A side by the refrigerant cooling heat exchanger 13 during the cooling operation. Thus, the refrigerant cooling expansion valve 12 is controlled so as to flow into the intermediate expansion valve 15 in the liquid single phase state, so that the refrigeration cycle can be performed without increasing the size and cost of the intermediate unit C. The refrigerant amount can be provided an air conditioner can be improved minor reduction and cooling capacity in.

(Second Embodiment)
Next, the air conditioner of 2nd Embodiment of this invention is demonstrated using FIG. FIG. 2 is a refrigeration cycle system diagram of an air conditioner according to a second embodiment of the present invention. The second embodiment is different from the first embodiment in the points described below, and the other points are basically the same as those in the first embodiment, and thus redundant description is omitted.

  In the second embodiment, a plurality of intermediate units C are connected to one outdoor unit A, and a plurality of indoor units B2a to B2n and B3a to B3n not having an indoor expansion valve are connected to each intermediate unit C. Yes. In other words, the number of indoor units B that can be operated by the operation of the outdoor unit A or the indoor units B that are greater than the total capacity are connected.

  The control device E also controls the gas side solenoid valve 8, the liquid side solenoid valve 9, the refrigerant cooling expansion valve 12 and the intermediate expansion valve 15 of the added intermediate unit C. And the control apparatus E is the case where one intermediate | middle unit C is not drive | operated at the time of air_conditionaing | cooling operation (namely, when not operating all the indoor units connected to the said intermediate | middle unit C, for example, indoor unit B2a-B2n). After fully closing the liquid side electromagnetic valve 9 of the intermediate unit C, the refrigerant in the indoor units B2a to B2n is recovered for a predetermined time, and the gas side electromagnetic valve 8 is fully closed after a predetermined time has elapsed. Moreover, the control apparatus E is in the case of heating operation, when one intermediate unit C is not operated (that is, when a plurality of indoor units connected to the intermediate unit C, for example, all the indoor units B2a to B2n are not operated). After the gas side electromagnetic valve 8 of the intermediate unit C is fully closed, the refrigerant in the indoor units B2a to B2n is recovered for a predetermined time, and the liquid side electromagnetic valve 9 is fully closed after the predetermined time has elapsed. As a result, the refrigerant does not flow through the indoor units B2a to B2n that are not in operation, and the refrigeration cycle state in which the refrigerant amount is insufficient is not achieved. Therefore, the indoor unit B combined with one outdoor unit A can be connected in a specified number or more or a specified total capacity.

It is a refrigerating cycle system diagram of the air harmony machine of a 1st embodiment of the present invention. It is a refrigeration cycle system diagram of the air conditioner of the second embodiment of the present invention.

  DESCRIPTION OF SYMBOLS 1 ... Outdoor gas side blocking valve, 2 ... Outdoor liquid side blocking valve, 3 ... Indoor fan, 4 ... Indoor heat exchanger, 5 ... Indoor expansion valve, 6a-6b ... Gas side branch pipe, 7a-7b ... Liquid side branch Pipe 8, Gas side solenoid valve, 9 Liquid side solenoid valve, 10 a Intermediate liquid side branch pipe (for bypass circuit branch), 10 b Intermediate liquid side branch pipe (for indoor unit branch), 12 Expansion for refrigerant cooling Valve, 13 ... Heat exchanger for cooling refrigerant, 14a ... Intermediate gas side branch pipe (for bypass circuit branch), 14b ... Intermediate gas side branch pipe (for indoor unit branch), 15 ... Intermediate expansion valve (for each indoor unit) , 21 ... compressor, 22 ... four-way valve, 23 ... outdoor heat exchanger, 24 ... outdoor expansion valve, 25 ... outdoor blower, A ... outdoor unit, B ... indoor unit, B1a-B1b ... indoor unit (first group Indoor unit), B2a to B2b ... Indoor unit (second group of rooms) Unit), C ... intermediate unit, C1 ... liquid side refrigerant piping, C2 ... gas side refrigerant piping, C3 ... bypass circuit, D ... communication piping, D1 ... liquid side communication piping, D2 ... gas side communication piping, E ... control device .

Claims (3)

An outdoor unit having a compressor and an outdoor heat exchanger;
A plurality of indoor units having an indoor heat exchanger and not having an indoor expansion valve;
A liquid side connecting pipe and a gas side connecting pipe that connect the outdoor unit and the plurality of indoor units;
Provided in the intermediate liquid side branch pipe interposed in the middle of the liquid side communication pipe, the intermediate gas side branch pipe interposed in the middle of the gas side communication pipe, and the refrigerant pipe on the indoor unit side of the intermediate liquid side branch pipe An intermediate unit having an intermediate expansion valve,
In an air conditioner comprising a control device for controlling the intermediate expansion valve,
The intermediate unit includes a bypass pipe connecting the refrigerant pipe on the outdoor unit side of the intermediate liquid side branch pipe and the refrigerant pipe on the outdoor unit side of the intermediate gas side branch pipe, and for cooling the refrigerant provided in the bypass pipe An expansion valve; and a refrigerant cooling heat exchanger that exchanges heat between the bypass pipe and the refrigerant pipe on the outdoor unit side of the intermediate liquid side branch pipe.
In the cooling operation, the control device cools the refrigerant that has become a gas-liquid two-phase flowing from the outdoor unit side with the refrigerant cooling heat exchanger and flows into the intermediate expansion valve in a liquid single-phase state. The air conditioner characterized by controlling the expansion valve for cooling the refrigerant.   2. The air conditioner according to claim 1, wherein the outdoor unit includes an outdoor expansion valve, and the control device controls the refrigerant flowing out from the outdoor unit side during cooling operation so as to be in a gas-liquid two-phase.   2. The intermediate unit according to claim 1, wherein the intermediate unit includes a plurality of intermediate units connected to the outdoor unit, and each of the intermediate units includes a refrigerant pipe on an outdoor unit side of the intermediate liquid side branch pipe and a refrigerant pipe on the intermediate gas side branch pipe. When the refrigerant pipe on the outdoor unit side is provided with a solenoid valve, the indoor unit is provided with the number of indoor units that can be operated by the operation of the outdoor unit or the total capacity or more, and the control device has the intermediate unit that is not operated, An air conditioner that performs a refrigerant recovery operation by controlling the electromagnetic valve so as not to be in a refrigeration cycle state in which a refrigerant amount is insufficient.

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