JP5277854B2 - Air conditioner - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an air conditioner capable of carrying out cooling and heating simultaneous operation adopting constitution of carrying out intermediate pressure injection of returning a refrigerant of intermediate pressure to a compression element on the subsequent stage side in a multistage compression type refrigerating cycle. <P>SOLUTION: The air conditioner capable of carrying out cooling and heating simultaneous operation adopts a multistage compression type compression mechanism 21 having two compression elements 21d, 21e as the compression mechanism 21 and constituted to compress a refrigerant discharged from the compression element 21d on the prior stage side sequentially by the compression element 21e on the subsequent stage side. A utilization side injection pipe 94 branching a part of the refrigerant flowing in liquid refrigerant branch pipes 92, 93 branched from a liquid refrigerant junction pipe 91, to return the part of the refrigerant to the compression element 21e on the subsequent stage side are connected to the respective liquid refrigerant branch pipes 92, 93, and utilization side economizer heat exchangers 68, 69 are provided for carrying out heat exchange with the refrigerant flowing in the utilization side injection pipe 94 corresponding to the refrigerant flowing in the respective liquid refrigerant branch pipes 92, 93. <P>COPYRIGHT: (C)2010,JPO&amp;INPIT

Description

  The present invention relates to an air conditioner, and more particularly to an air conditioner capable of simultaneous cooling and heating.

Conventionally, there is an air conditioner capable of simultaneous cooling and heating as disclosed in Patent Document 1. Moreover, as an air conditioner capable of switching between cooling and heating, a compressor having two front and rear compression elements connected in series as shown in Patent Document 2, an outdoor heat exchanger, an indoor heat exchanger, Two expansion valves provided between the outdoor heat exchanger and the indoor heat exchanger, a gas-liquid separator that gas-liquid separates the refrigerant flowing between the two expansion valves, and the downstream side of the refrigerant from the gas-liquid separator There is a rear-stage injection pipe for returning to the compression element, and an air-conditioning apparatus that performs intermediate-pressure injection that returns the intermediate-pressure refrigerant to the rear-stage compression element in a two-stage compression refrigeration cycle.
JP-A-6-317360 JP 2007-232263 A

  However, in an air conditioner that can be operated simultaneously with cooling and heating, unlike an air conditioner that can be switched between cooling and heating, an intermediate pressure injection that returns an intermediate pressure refrigerant to a compression element on the rear stage side in a two-stage compression refrigeration cycle. There is no one that employs a configuration that performs the above.

  An object of the present invention is to provide an air conditioner capable of simultaneous cooling and heating that employs a configuration in which intermediate pressure injection is performed to return an intermediate pressure refrigerant to a downstream compression element in a multistage compression refrigeration cycle.

  An air conditioner according to a first invention includes a compression mechanism, a heat source side heat exchanger, a liquid refrigerant junction pipe connected to the heat source side heat exchanger, and a heat source side expansion mechanism provided in the liquid refrigerant junction pipe. A plurality of use side heat exchangers, a liquid refrigerant branch pipe branched from the liquid refrigerant junction pipe and connected to each use side heat exchanger, and a use side expansion mechanism provided in each liquid refrigerant branch pipe A heat radiation operation switching state in which the heat source side heat exchanger functions as a radiator of the refrigerant discharged from the compression mechanism, and an evaporation operation switching state in which the heat source side heat exchanger functions as an evaporator of the refrigerant flowing through the liquid refrigerant junction pipe. A switchable heat source side switching mechanism and a high pressure gas refrigerant pipe connected between the discharge side and the heat source side switching mechanism of the compression mechanism and branching before the refrigerant discharged from the compression mechanism flows into the heat source side switching mechanism And provided for each user-side heat exchanger A cooling operation switching state in which the use side heat exchanger functions as an evaporator of the refrigerant flowing through the liquid refrigerant branch pipe, and a heating operation switching state in which the use side heat exchanger functions as a radiator of the refrigerant flowing in the high pressure gas refrigerant pipe. A switchable use side switching mechanism and a low pressure gas refrigerant pipe for sending the refrigerant evaporated in each use side heat exchanger to the suction side of the compression mechanism are provided. The compression mechanism has a plurality of compression elements, and is configured to sequentially compress the refrigerant discharged from the front-stage compression elements of the plurality of compression elements with the rear-stage compression elements, The liquid refrigerant merging pipe is connected to a heat source side injection pipe that branches a part of the refrigerant flowing through the liquid refrigerant merging pipe and returns it to the compression element on the rear stage side, and the refrigerant flowing through the liquid refrigerant merging pipe and the heat source side injection pipe A heat source side economizer heat exchanger that performs heat exchange with the refrigerant flowing through the refrigerant is provided, and in each liquid refrigerant branch pipe, a part of the refrigerant flowing through each liquid refrigerant branch pipe is branched and used as a compression element on the rear stage side. A user-side economizer heat exchanger that performs heat exchange between the refrigerant that flows through the liquid refrigerant branch pipes and the refrigerant that flows through the corresponding user-side injection pipes is provided along with the return-use injection pipe to be returned.Here, the “compression mechanism” refers to a compressor in which a plurality of compression elements are integrally incorporated, a compressor in which a single compression element is incorporated, and / or a compressor in which a plurality of compression elements are incorporated. This means a configuration that includes a unit connected. In addition, “sequentially compresses the refrigerant discharged from the compression element on the front stage among the plurality of compression elements with the compression element on the rear stage” is referred to as “compression element on the front stage” and “compression element on the rear stage” It is not only meant to include two compression elements connected in series, but a plurality of compression elements are connected in series, and the relationship between the compression elements is the above-mentioned “previous-side compression element” ”And“ compression element on the rear stage side ”.

  Compression mechanism, heat source side heat exchanger, liquid refrigerant junction pipe, heat source side expansion mechanism, multiple usage side heat exchangers, multiple liquid refrigerant branch pipes, heat source side switching mechanism, high pressure gas refrigerant pipe, and multiple usage side switching mechanisms And a low-pressure gas refrigerant pipe capable of simultaneous cooling and heating, the refrigerant having a plurality of compression elements as a compression mechanism and discharged from the compression element on the front stage among the plurality of compression elements In order to improve the operating efficiency of the multistage compression refrigeration cycle, in the multistage compression refrigeration cycle, the multistage compression type refrigeration cycle is used. A configuration for performing intermediate pressure injection on the liquid side of the heat source side heat exchanger is provided in the same manner as an air conditioner capable of cooling / heating switching operation that performs intermediate pressure injection for returning intermediate pressure refrigerant to the downstream compression element. Rukoto is considered.

  However, in an air conditioner capable of simultaneous cooling and heating, there is a simultaneous cooling and heating operation in which a use side heat exchanger that performs cooling and a use side heat exchanger that performs heating coexist, and cooling is performed during this cooling and heating simultaneous operation. Refrigerant in which exchange of refrigerant is mainly performed between the use side heat exchanger and the use side heat exchanger for heating, and exchange is performed between the plurality of use side heat exchangers and the heat source side heat exchanger. The flow rate of will decrease. For this reason, in simultaneous cooling and heating operation, it becomes difficult to secure the flow rate of the refrigerant supplied to the intermediate pressure injection, and it becomes difficult to improve the operation efficiency in the multistage compression refrigeration cycle.

  Therefore, in this air conditioner, the refrigerant flowing through the liquid refrigerant merging pipe is connected to the liquid refrigerant merging pipe connected to the heat source side injection pipe that branches a part of the refrigerant flowing through the liquid refrigerant merging pipe and returns to the subsequent compression element. The heat source side economizer heat exchanger that exchanges heat with the refrigerant that flows through the heat source side injection pipe is provided, and a part of the refrigerant that flows through each liquid refrigerant branch pipe is branched into each liquid refrigerant branch pipe to form a downstream compression element. A user side economizer heat exchanger is provided for connecting the returning user side injection pipe and performing heat exchange between the refrigerant flowing through each liquid refrigerant branch pipe and the refrigerant flowing through the corresponding use side injection pipe.

  Thus, during simultaneous cooling and heating operation, the refrigerant exchanged between the use side heat exchanger that performs cooling and the use side heat exchanger that performs heating is exchanged via the use side economizer heat exchanger. Therefore, it is possible to secure the flow rate of the refrigerant supplied to the intermediate pressure injection for returning the refrigerant to the compression element on the rear stage through the user side injection pipe corresponding to the user side economizer heat exchanger. In addition, it is possible to improve the operation efficiency in the multistage compression refrigeration cycle, and therefore, in the multistage compression refrigeration cycle, the cooling / heating employing a configuration in which intermediate pressure injection is performed to return the intermediate pressure refrigerant to the compression element on the rear stage side. An air conditioner capable of simultaneous operation can be provided.

Further, in this air conditioner, a heat source unit including at least a part of the liquid refrigerant junction pipe, a compression mechanism, a heat source side heat exchanger, a heat source side injection pipe, and a heat source side economizer heat exchanger, and a use side heat exchanger are provided. A plurality of use units including at least a branch unit including at least a part of the liquid refrigerant branch pipe that is different from the part included in the heat source unit and a use-side economizer heat exchanger; A liquid refrigerant communication tube comprising a portion connecting between the units, a high pressure gas refrigerant communication tube comprising a portion connecting between the heat source unit and the branch unit in the high pressure gas refrigerant tube, and a heat source among the low pressure gas refrigerant tubes. The unit is configured by connecting a low-pressure gas refrigerant communication pipe composed of a portion connecting the unit and the branch unit.

In this air conditioner, the use-side economizer heat exchanger is provided in a branch unit that is separate from the use unit and heat source unit. A heat exchanger can be added.

In addition, since the liquid refrigerant communication pipe is often long in length, for example, from the heat source side heat exchanger to the usage side heat exchanger, such as cooling operation in which only the usage side heat exchanger that performs cooling exists. When the flow rate of the refrigerant flowing through the liquid refrigerant merging pipe is large, the pressure loss of the refrigerant flowing through the liquid refrigerant merging pipe tends to increase from the heat source side heat exchanger toward the use side heat exchanger.

However, in this air conditioner, a heat source side injection pipe is connected to a part included in the heat source unit of the liquid refrigerant junction pipe and a part of the refrigerant flowing through the liquid refrigerant junction pipe is returned to the subsequent compression element. Since the heat source side economizer heat exchanger that performs heat exchange between the refrigerant flowing through the liquid refrigerant merging pipe and the refrigerant flowing through the heat source side injection pipe is provided, the liquid is directed from the heat source side heat exchanger toward the usage side heat exchanger. When the flow rate of the refrigerant flowing through the refrigerant junction pipe is large, heat exchange in the heat source side economizer heat exchanger can be performed before the pressure drop due to pressure loss in the liquid refrigerant communication pipe occurs, and the compression element on the rear stage side Therefore, the flow rate of the refrigerant that can be returned to is less likely to decrease, and the intermediate pressure injection can be sufficiently performed.

Furthermore, in this air conditioner, the use-side injection pipe is connected to a portion included in the branch unit in the liquid refrigerant junction pipe.

When the use side economizer heat exchanger is provided in the branch unit, if the use side injection pipe is joined to the heat source side injection pipe or directly connected to the compression element on the rear stage side, a part of the use side injection pipe (hereinafter, The “use side injection communication pipe” is present as one of the refrigerant pipes connecting the branch unit and the heat source unit. Therefore, the apparatus configuration is connected through four types of refrigerant pipes, a low-pressure gas refrigerant communication pipe and a user-side injection communication pipe.

Therefore, in this air conditioner, the use-side injection pipe is connected to a portion included in the branch unit in the liquid refrigerant junction pipe. And when performing only the cooling operation in which the use side heat exchanger functions as a refrigerant evaporator, or when performing only the heating operation in which the use side heat exchanger functions as a refrigerant radiator, the heat source side injection pipe A part of the refrigerant flowing through the liquid refrigerant merging pipe is branched by, and the refrigerant flowing through the heat source side injection pipe is heated while the refrigerant flowing through the liquid refrigerant merging pipe is cooled by the heat source side economizer heat exchanger, and the heated heat source side When the refrigerant flowing through the injection pipe is returned to the compression element on the rear stage side and cooling operation and heating operation are mixed, a part of the refrigerant flowing through the corresponding liquid refrigerant branch pipe is branched by the use side injection pipe. The refrigerant flowing through the user side injection pipe is heated while cooling the refrigerant flowing through the liquid refrigerant branch pipe by the corresponding user side economizer heat exchanger, The refrigerant flowing through the heated the usage injection tube through the liquid refrigerant junction pipe and the heat source-side injection pipe, and returned to the second-stage compression element.

As a result, for example, exchange between a plurality of use side heat exchangers and heat source side heat exchangers such as simultaneous cooling and heating operation in which a use side heat exchanger that performs cooling and a use side heat exchanger that performs heating are mixed. When the flow rate of the refrigerant is small, the refrigerant flowing through the use side injection pipe is passed through the liquid refrigerant junction pipe without exchanging the refrigerant between the plurality of use side heat exchangers and the heat source side heat exchanger. By sending it to the heat source unit, intermediate pressure injection can be performed, and a device configuration that does not require a user-side injection communication pipe can be achieved.

  An air conditioner according to a second aspect of the invention is the air conditioner according to the first aspect of the invention, wherein the use side economizer heat exchanger is provided between the use side heat exchanger and the use side expansion mechanism.

  In this air conditioner, since the use side economizer heat exchanger is provided between the use side heat exchanger and the use side expansion mechanism, the refrigerant that has passed through the use side heat exchanger is cooled by the use side expansion mechanism. Before the pressure is reduced, the refrigerant passes through the use-side economizer heat exchanger, and the refrigerant flowing through the use-side economizer heat exchanger is maintained at a high pressure.

  As a result, the amount of heat exchanged in the use-side economizer heat exchanger increases, so that the flow rate of the refrigerant flowing through the use-side injection pipe, that is, the flow rate of the refrigerant supplied to the intermediate pressure injection can be increased. The operation efficiency in the compression refrigeration cycle can be further improved.

An air conditioner according to a third aspect of the invention is the air conditioner according to the first or second aspect of the invention , wherein a plurality of liquid refrigerants are formed from the position where the use side injection pipe is connected among the liquid refrigerant junction pipe and the liquid refrigerant junction pipe. A liquid tube opening / closing mechanism is provided at a portion between the branch portion to the branch tube.

  In this air conditioner, when the refrigerant flowing through the use side injection pipe is sent to the heat source unit through the liquid refrigerant junction pipe, refrigerant other than the refrigerant supplied to the intermediate pressure injection is not allowed to flow out from the plurality of liquid refrigerant branch pipes. The refrigerant flowing through the use side injection pipe can be sent to the heat source unit through the liquid refrigerant junction pipe to perform intermediate pressure injection.

An air conditioner according to a fourth aspect of the invention is the air conditioner according to any of the first to third aspects of the invention, wherein the heat source side injection pipe is in liquid refrigerant communication with the heat source side economizer heat exchanger in the liquid refrigerant junction pipe. It connects so that a part of refrigerant | coolant which flows through a liquid refrigerant junction pipe may branch from the part with a pipe | tube.

  In this air conditioner, the gas refrigerant sent from the use side injection pipe to the heat source unit through the liquid refrigerant junction pipe can be subjected to intermediate pressure injection without passing through the heat source side economizer heat exchanger. Compared with the case of passing through the heat source side economizer heat exchanger, the pressure loss of the gas refrigerant provided for the intermediate pressure injection can be reduced.

An air conditioner according to a fifth aspect of the present invention is the air conditioner according to any of the first to fourth aspects of the invention, wherein the use side economizer heat exchanger radiates heat in the corresponding use side heat exchanger and then the liquid refrigerant branch. It is a heat exchanger which has a flow path which flows so that the refrigerant which flows through a pipe and the refrigerant which flows through a use side injection pipe may counter.

  In this air conditioner, since the temperature difference between the refrigerants in the use-side economizer heat exchanger can be reduced, the amount of exchange heat can be increased, and the flow rate of the refrigerant provided for intermediate pressure injection can be further increased. Can do.

An air conditioner according to a sixth aspect is the air conditioner according to any one of the first to fifth aspects, wherein the compression mechanism compresses the refrigerant to a pressure exceeding the critical pressure.

An air conditioner according to a seventh aspect is the air conditioner according to the sixth aspect, wherein the refrigerant is carbon dioxide.

  As described above, according to the present invention, the following effects can be obtained.

In the first, sixth, and seventh inventions, during the cooling and heating simultaneous operation, the refrigerant exchanged between the use side heat exchanger that performs cooling and the use side heat exchanger that performs heating is the use side economizer heat exchange. It is possible to secure the flow rate of the refrigerant supplied to the intermediate pressure injection that returns the refrigerant to the compression element on the rear stage side through the usage side injection pipe corresponding to the usage side economizer heat exchanger. Therefore, during simultaneous cooling and heating operation, it is possible to improve the operation efficiency in the multistage compression refrigeration cycle, and therefore, in the multistage compression refrigeration cycle, the intermediate pressure refrigerant is returned to the downstream compression element. It is possible to provide an air conditioner capable of simultaneous cooling and heating that employs a configuration for performing pressure injection. In addition, since the user-side economizer heat exchanger is installed in a branch unit that is separate from the user unit and heat source unit, the user-side economizer heat exchanger can be installed without significantly changing the equipment configuration of the user unit or heat source unit. Can be added. In addition, when the flow rate of the refrigerant flowing through the liquid refrigerant junction pipe from the heat source side heat exchanger toward the user side heat exchanger is large, the heat source side economizer before the pressure drop due to the pressure loss in the liquid refrigerant communication pipe occurs. Heat exchange in the heat exchanger can be performed, and the flow rate of the refrigerant that can be returned to the compression element on the rear stage is less likely to decrease, so that intermediate pressure injection can be sufficiently performed. Furthermore, exchange is performed between a plurality of use side heat exchangers and heat source side heat exchangers such as simultaneous cooling and heating operation in which a use side heat exchanger for cooling and a use side heat exchanger for heating are mixed. When the flow rate of the refrigerant is small, the refrigerant flowing through the use side injection pipe is transferred to the heat source unit through the liquid refrigerant junction pipe without exchanging the refrigerant between the plurality of use side heat exchangers and the heat source side heat exchanger. The intermediate pressure injection can be performed by sending, and a device configuration in which a part of the use side injection pipe does not exist as one of the refrigerant pipes connecting the branch unit and the heat source unit can be obtained. .

  In the second invention, the refrigerant flowing through the use-side economizer heat exchanger is maintained at a high pressure, and the amount of exchange heat in the use-side economizer heat exchanger increases, so the flow rate of the refrigerant flowing through the use-side injection pipe, That is, the flow rate of the refrigerant provided for the intermediate pressure injection can be increased, and the operation efficiency in the multistage compression refrigeration cycle can be further improved.

In the third invention, when sending the refrigerant flowing through the use side injection pipe to the heat source unit through the liquid refrigerant junction pipe, the refrigerant other than the refrigerant supplied to the intermediate pressure injection does not flow out from the plurality of liquid refrigerant branch pipes. The refrigerant flowing through the use side injection pipe can be sent to the heat source unit through the liquid refrigerant junction pipe to perform intermediate pressure injection.

In the fourth aspect of the invention, the gas refrigerant sent from the use side injection pipe to the heat source unit through the liquid refrigerant junction pipe can be subjected to intermediate pressure injection without passing through the heat source side economizer heat exchanger. Compared with the case where the heat source side economizer heat exchanger is passed, the pressure loss of the gas refrigerant provided for the intermediate pressure injection can be reduced.

In the fifth invention, since the temperature difference between refrigerants in the use-side economizer heat exchanger can be reduced, the amount of exchange heat can be increased, and the flow rate of refrigerant supplied to intermediate pressure injection is further increased. Can do.

  Hereinafter, embodiments of an air-conditioning apparatus according to the present invention will be described based on the drawings.

(1) Configuration of Air Conditioner FIG. 1 is a schematic configuration diagram of an air conditioner 1 according to an embodiment of the present invention. The air conditioner 1 is a device used for indoor air conditioning such as a building by performing a vapor compression refrigeration cycle operation.

  The air conditioner 1 mainly uses one heat source unit 2, a plurality (two in this embodiment) of utilization units 4 and 5, a branch unit 6, and the heat source unit 2 via the branch unit 6. The refrigerant communication pipes 8, 9, 10 and the like for connecting the units 4 and 5 are provided, and the cooling and heating simultaneous operation for selecting the cooling and heating for each use unit is possible. That is, the refrigerant circuit 11 of the air conditioner 1 is configured by connecting the heat source unit 2, the utilization units 4 and 5, the branch unit 6, the refrigerant communication pipes 8, 9, and 10. The refrigerant circuit 11 is filled with a refrigerant (here, carbon dioxide) that operates in the supercritical region.

<Usage unit>
The usage units 4 and 5 are installed by being embedded or suspended in an indoor ceiling of a building or the like, or by being hung on an indoor wall surface. The utilization units 4 and 5 are connected to the heat source unit 2 through the refrigerant communication tubes 8, 9, and 10 and the branch unit 6, and constitute a part of the refrigerant circuit 11.

  Next, the configuration of the usage units 4 and 5 will be described. Since the usage unit 4 and the usage unit 5 have the same configuration, only the configuration of the usage unit 4 will be described here, and the configuration of the usage unit 5 is denoted by reference numerals in the 40s indicating each part of the usage unit 4. Instead, reference numerals in the 50s are attached and description of each part is omitted.

  The usage unit 4 mainly has a usage-side refrigerant circuit 11a (in the usage unit 5, the usage-side refrigerant circuit 11b). This usage-side refrigerant circuit 11a mainly has a usage-side heat exchanger 42.

  The use side heat exchanger 42 is a heat exchanger that processes an indoor air conditioning load by exchanging heat between the refrigerant and indoor air, and the first liquid refrigerant branch pipe 43 is connected to the liquid side thereof. The first gas refrigerant branch pipe 44 is connected to the gas side.

<Heat source unit>
The heat source unit 2 is installed on the roof of a building or the like, and is connected to the utilization units 4 and 5 through the refrigerant communication pipes 8, 9, and 10, and the branch unit 6. It is composed.

  Next, the configuration of the heat source unit 2 will be described. The heat source unit 2 mainly has a heat source side refrigerant circuit 11c. The heat source side refrigerant circuit 11c mainly includes a compression mechanism 21, a first switching mechanism 22 as a heat source side switching mechanism, a heat source side heat exchanger 23, a heat source side expansion mechanism 24, a second switching mechanism 25, A heat source side injection pipe 34 and a heat source side economizer heat exchanger 36 are provided.

  The compression mechanism 21 is a compressor that compresses the refrigerant in two stages with two compression elements. The compression mechanism 21 has a sealed structure in which a compressor drive motor 21b, a drive shaft 21c, and compression elements 21d and 21e are accommodated in a casing 21a. The compressor drive motor 21b is connected to the drive shaft 21c. The drive shaft 21c is connected to the two compression elements 21d and 21e. That is, in the compression mechanism 21, two compression elements 21d and 21e are connected to a single drive shaft 21c, and the two compression elements 21d and 21e are both rotationally driven by a compressor drive motor 21b. It has a stage compression structure. The compression elements 21d and 21e are volumetric compression elements such as a rotary type and a scroll type. The compression mechanism 21 sucks the refrigerant from the suction pipe 26, compresses the sucked refrigerant by the compression element 21 d on the front stage side, discharges the refrigerant to the intermediate refrigerant pipe 27, and refrigerant discharged to the intermediate refrigerant pipe 27. Is sucked into the compression element 21e on the rear stage side, further compressed, and then discharged to the discharge pipe 28. The suction pipe 26 is a refrigerant pipe connected to the suction side of the compression mechanism 21 and the low-pressure gas refrigerant communication pipe 10 (described later). The discharge pipe 28 is a refrigerant pipe connected to the discharge side of the compression mechanism 21. As described above, the compression mechanism 21 has a plurality (here, two) of compression elements 21d and 21e, and the refrigerant discharged from the compression element 21d on the preceding stage of the compression elements 21d and 21e. Are sequentially compressed by the compression element 21e on the rear stage side.

  The first switching mechanism 22 can switch between a heat radiation operation switching state in which the heat source side heat exchanger 23 functions as a refrigerant radiator and an evaporation operation switching state in which the heat source side heat exchanger 23 functions as a refrigerant evaporator. The first port 22 a is connected to the discharge side of the compression mechanism 21 through the discharge pipe 28, and the second port 22 b is connected to the gas side of the heat source side heat exchanger 23 through the heat source side gas refrigerant pipe 29. The third port 22c is connected to the suction side of the compression mechanism 21 through the suction pipe 26, and the fourth port 22d is connected to the suction side of the compression mechanism 21 through the capillary tube 22e. . The first switching mechanism 22 connects the first port 22a and the second port 22b and connects the third port 22c and the fourth port 22d (corresponding to the heat radiation operation switching state, the first switching mechanism in FIG. 1). 22) (refer to the solid line of FIG. 22), the second port 22b and the third port 22c are connected, and the first port 22c and the fourth port 22d are connected (corresponding to the evaporation operation switching state, the first switching mechanism of FIG. It is possible to switch over (see the dashed line 22). The heat source side gas refrigerant pipe 29 is a refrigerant pipe that connects the second port 22 b of the first switching mechanism 22 and the gas side of the heat source side heat exchanger 23. The first switching mechanism 22 is not limited to a four-way switching valve, and is configured to have a function of switching the refrigerant flow direction similar to that described above, for example, by combining a plurality of electromagnetic valves. It may be a thing.

  The heat source side heat exchanger 23 is a heat exchanger that functions as a refrigerant radiator or evaporator by exchanging heat between the refrigerant and outdoor air, and the first liquid refrigerant junction pipe 30 is connected to the liquid side thereof. The heat source side gas refrigerant pipe 29 is connected to the gas side.

  The heat source side expansion mechanism 24 is an electric expansion valve that performs decompression of the refrigerant flowing in the heat source side refrigerant circuit 10 c and is provided in the first liquid refrigerant merging pipe 30.

  When the 2nd switching mechanism 25 comprises the air conditioning apparatus in which cooling / heating simultaneous operation is possible like this embodiment (namely, when using the heat source unit 2 as a heat source unit of the air conditioning apparatus in which cooling / heating simultaneous operation is possible). ), When the high-pressure gas refrigerant is sent to the use-side refrigerant circuits 11a and 11b (hereinafter referred to as the heating load required operation state), the discharge side of the compression mechanism 21 and the high-pressure gas refrigerant communication pipe 9 are connected, Unlike the present embodiment, when an air conditioner capable of switching between cooling and heating is configured (that is, when the heat source unit 2 is used as a heat source unit of an air conditioning apparatus capable of switching between cooling and heating), a high-pressure gas refrigerant is used. This is a four-way switching valve capable of switching the refrigerant flow path in the heat source side refrigerant circuit 11c so as to connect the communication pipe 9 and the suction side of the compression mechanism 21, and the first port 25a thereof is The first high-pressure gas refrigerant pipe 31 branched from the outlet pipe 28 and the discharge pipe 28 is connected to the discharge side of the compression mechanism 21, and the second port 25b is connected to the suction side of the compression mechanism 21 through the capillary tube 25e. The third port 25 c is connected to the suction side of the compression mechanism 21 through the suction pipe 26, and the fourth port 25 d is connected to the high pressure gas refrigerant communication pipe 9 through the second high pressure gas refrigerant pipe 32. Yes. Then, as described above, the second switching mechanism 25 connects the first port 25a and the second port 25b and connects the third port 25c and the fourth port 25d (corresponding to the cooling operation state at the time of cooling / heating switching, 1) (refer to the solid line of the second switching mechanism 25 in FIG. 1), and the second port 25b and the third port 25c are connected and the first port 25a and the fourth port 25d are connected (corresponding to the heating load request operation state). It is possible to perform switching to be performed (see the broken line of the second switching mechanism 25 in FIG. 1). The first high-pressure gas refrigerant pipe 31 is a refrigerant pipe that connects the discharge pipe 28 and the first port 25 a of the second switching mechanism 25, and the second high-pressure gas refrigerant pipe 32 is the fourth port of the second switching mechanism 25. This is a refrigerant pipe connecting 25d and the high-pressure gas refrigerant communication pipe 9. The second switching mechanism 25 is not limited to the four-way switching valve, and is configured to have the function of switching the refrigerant flow direction as described above, for example, by combining a plurality of electromagnetic valves. It may be a thing.

  The heat source side injection pipe 34 is a refrigerant pipe that branches a part of the refrigerant flowing through the first liquid refrigerant merging pipe 30 and returns it to the compression element 21 e on the rear stage side of the compression mechanism 21. One end of the heat source side injection pipe 34 is connected to a portion closer to the liquid refrigerant communication pipe 8 than the position where the heat source side expansion mechanism 24 of the first liquid refrigerant junction pipe 30 is provided, and the other end is an intermediate refrigerant pipe. 27. Although not adopted here, the heat source side injection pipe 34 may be directly connected to the compression element 21e on the rear stage side. The heat source side injection pipe 34 is provided with a heat source side injection valve 35 capable of opening degree control. The heat source side injection valve 36 is an electric expansion valve.

  The heat source side economizer heat exchanger 36 is decompressed to near the intermediate pressure in the refrigeration cycle by the refrigerant flowing through the first liquid refrigerant merging pipe 30 and the refrigerant flowing through the heat source side injection pipe 34 (more specifically, by the heat source side injection valve 35). It is a heat exchanger which performs heat exchange with the refrigerant after. The heat source side economizer heat exchanger 36 is provided in a portion closer to the liquid refrigerant communication pipe 8 than the position where the heat source side expansion mechanism 24 of the first liquid refrigerant merging pipe 30 is provided. The liquid refrigerant junction pipe 30 is provided in a portion closer to the liquid refrigerant communication pipe 8 than the position where the heat source side injection pipe 34 is connected. Although not adopted here, the heat source side economizer heat exchanger 36 includes a position where the heat source side expansion mechanism 24 of the first liquid refrigerant merging pipe 30 is provided and a position where the heat source side injection pipe 34 is connected. It may be provided in the part between. Then, the heat source side economizer heat exchanger 36 has a flow path that flows so that the refrigerant flowing through the first liquid refrigerant merging pipe 30 and the refrigerant flowing through the heat source side injection pipe 34 face each other after radiating heat in the heat source side heat exchanger 23. Have.

  Further, the heat source unit 2 includes a first usage-side injection for returning refrigerant flowing through second usage-side injection pipes 63 and 64 (described later) provided in the branch unit 6 to the compression element 21e on the rear stage side of the compression mechanism 21. A pipe 33 is provided, one end of which is connected to a use-side injection communication pipe 14 (described later), and the other end is connected to a downstream portion of the heat source side injection valve 35 of the heat source side injection pipe 34. . Although not adopted here, both the injection pipes 33 and 34 may be separately connected to the intermediate refrigerant pipe 27 and the compression element 21e on the rear stage side.

<Branch unit>
For example, the branch unit 6 is installed at a position near the use units 4 and 5 such as indoors such as a building, and between the use units 4 and 5 and the heat source unit 2 together with the refrigerant communication tubes 8, 9, and 10. And constitutes a part of the refrigerant circuit 11.

  Next, the configuration of the branch unit 6 will be described. The branch unit 6 mainly has a liquid side branch circuit 11d and a gas side branch circuit 11e.

  The liquid side branch circuit 11d mainly includes the second liquid refrigerant junction pipe 61, the second liquid refrigerant branch pipes 62 and 63, the use side expansion mechanisms 41 and 51, the second use side injection pipes 64 and 66, and the use. The side economizer heat exchangers 68 and 69 and the third usage side injection pipe 70 are provided.

  The second liquid refrigerant merging pipe 61 has one end connected to the liquid refrigerant communication pipe 8 and the other end connected to the second liquid refrigerant branch pipes 62 and 63. Here, a refrigerant pipe composed of the first liquid refrigerant merging pipe 30, the liquid refrigerant merging pipe 8 and the second liquid refrigerant merging pipe 61 is referred to as a liquid refrigerant merging pipe 91.

  The second liquid refrigerant branch pipe 62 is a refrigerant pipe corresponding to the usage unit 4, one end of which is connected to the third liquid refrigerant branch pipe 12 corresponding to the usage unit 4, and the other end is the liquid refrigerant junction pipe 91. Is connected to the second liquid refrigerant merging pipe 61. The third liquid refrigerant branch pipe 12 is a refrigerant pipe that connects the second liquid refrigerant branch pipe 62 of the branch unit 6 and the first liquid refrigerant branch pipe 43 of the utilization unit 4. Here, a refrigerant pipe composed of the first liquid refrigerant branch pipe 43, the third liquid refrigerant branch pipe 12 and the second liquid refrigerant branch pipe 62 is referred to as a liquid refrigerant branch pipe 92. The use side expansion mechanism 41 is provided in the second liquid refrigerant branch pipe 62. The use side expansion mechanism 41 is an electric expansion valve that adjusts the flow rate of the refrigerant flowing in the use unit 4, that is, the use side refrigerant circuit 10a.

  The second liquid refrigerant branch pipe 63 is a refrigerant pipe corresponding to the usage unit 5, one end of which is connected to the third liquid refrigerant branch pipe 13 corresponding to the usage unit 5, and the other end is the liquid refrigerant junction pipe 91. Is connected to the second liquid refrigerant merging pipe 61. The third liquid refrigerant branch pipe 13 is a refrigerant pipe connecting the second liquid refrigerant branch pipe 63 of the branch unit 6 and the first liquid refrigerant branch pipe 53 of the usage unit 5. Here, a refrigerant pipe composed of the first liquid refrigerant branch pipe 53, the third liquid refrigerant branch pipe 13 and the second liquid refrigerant branch pipe 63 is referred to as a liquid refrigerant branch pipe 93. The use side expansion mechanism 51 is provided in the second liquid refrigerant branch pipe 63. The use side expansion mechanism 51 is an electric expansion valve that adjusts the flow rate of the refrigerant flowing in the use unit 5, that is, the use side refrigerant circuit 10b.

  The second use side injection pipe 64 branches a part of the refrigerant flowing through the second liquid refrigerant branch pipe 62 constituting the liquid refrigerant branch pipe 92 corresponding to the use unit 4 to compress the compression element 21e on the rear stage side of the compression mechanism 21. It is a refrigerant pipe for returning to. One end of the second usage side injection pipe 64 is connected to a portion closer to the third liquid refrigerant branch pipe 12 than the position where the usage side expansion mechanism 41 of the second liquid refrigerant branch pipe 62 is provided, and the other end. Is connected to the third usage-side injection pipe 70. The second usage-side injection pipe 64 is provided with a usage-side injection valve 65 capable of opening degree control. The use-side injection valve 65 is an electric expansion valve.

  The second use side injection pipe 66 branches a part of the refrigerant flowing through the second liquid refrigerant branch pipe 63 constituting the liquid refrigerant branch pipe 93 corresponding to the use unit 5 and compresses the compression element 21e on the rear stage side of the compression mechanism 21. It is a refrigerant pipe for returning to. The second usage side injection pipe 66 has one end connected to a portion closer to the third liquid refrigerant branch pipe 13 than the position where the usage side expansion mechanism 51 of the second liquid refrigerant branch pipe 63 is provided, and the other end. Is connected to the third usage-side injection pipe 70. The second usage-side injection pipe 66 is provided with a usage-side injection valve 67 capable of opening degree control. The use side injection valve 67 is an electric expansion valve.

  The third usage-side injection pipe 70 is a refrigerant pipe that connects the second usage-side injection pipes 64 and 66 of the branch unit 6 and the first usage-side injection pipe 33 of the heat source unit 2. Here, the refrigerant pipe composed of the second usage side injection pipes 64 and 66, the usage side injection connecting pipe 14 and the first usage side injection pipe 33 is referred to as a usage side injection pipe 94.

  The use-side economizer heat exchanger 68 includes a refrigerant that flows through the second liquid refrigerant branch pipe 62 that constitutes the liquid refrigerant branch pipe 92 corresponding to the use unit 4 and a second use side injection pipe 64 that constitutes the use side injection pipe 94. It is a heat exchanger that performs heat exchange with the flowing refrigerant (more specifically, the refrigerant after being reduced to the vicinity of the intermediate pressure in the refrigeration cycle by the use-side injection valve 65). The use side economizer heat exchanger 68 is provided in a portion closer to the third liquid refrigerant branch pipe 12 than the position where the use side expansion mechanism 41 of the second liquid refrigerant branch pipe 62 is provided. The second liquid refrigerant branch pipe 62 is provided at a portion between the position where the use side expansion mechanism 41 is provided and the position where the second use side injection pipe 64 is connected. Although not adopted here, the use side economizer heat exchanger 68 is closer to the third liquid refrigerant branch pipe 12 than the position where the second use side injection pipe 64 of the second liquid refrigerant branch pipe 62 is connected. It may be provided in this part. Then, the use-side economizer heat exchanger 68 radiates heat in the corresponding use-side heat exchanger 42 so that the refrigerant flowing through the second liquid refrigerant branch pipe 62 and the refrigerant flowing through the second use-side injection pipe 64 face each other. It has a flowing channel.

  The use-side economizer heat exchanger 69 includes a refrigerant that flows through the second liquid refrigerant branch pipe 63 that constitutes the liquid refrigerant branch pipe 93 that corresponds to the use unit 5, and a second use side injection pipe 66 that constitutes the use side injection pipe 94. It is a heat exchanger that performs heat exchange with the flowing refrigerant (more specifically, the refrigerant after being reduced to near the intermediate pressure in the refrigeration cycle by the use-side injection valve 67). The use side economizer heat exchanger 69 is provided in a portion closer to the third liquid refrigerant branch pipe 13 than the position where the use side expansion mechanism 51 of the second liquid refrigerant branch pipe 63 is provided. The second liquid refrigerant branch pipe 63 is provided at a portion between the position where the use side expansion mechanism 51 is provided and the position where the second use side injection pipe 66 is connected. Although not adopted here, the use side economizer heat exchanger 69 is closer to the third liquid refrigerant branch pipe 13 than the position where the second use side injection pipe 66 of the second liquid refrigerant branch pipe 63 is connected. It may be provided in this part. The use-side economizer heat exchanger 69 then causes the refrigerant flowing through the second liquid refrigerant branch pipe 63 and the refrigerant flowing through the second use-side injection pipe 66 to face each other after radiating heat in the corresponding use-side heat exchanger 52. It has a flowing channel.

  As described above, a part of the refrigerant flowing through the liquid refrigerant branch pipes 92 and 93 is branched into the liquid refrigerant branch pipes 92 and 93 (here, the second liquid refrigerant branch pipes 62 and 63, respectively). The second usage side injection pipes 64 and 66 constituting the usage side injection pipe 94 returning to the compression element 21e on the rear stage side of the 21 are connected, and the usage side injection corresponding to the refrigerant flowing through the liquid refrigerant branch pipes 92 and 93 is connected. Use side economizer heat exchangers 68 and 69 for exchanging heat with the refrigerant flowing through the pipes 64 and 66 are provided, and second use side injection pipes 64 and 66 corresponding to the use side economizer heat exchangers 68 and 69 are provided. It is possible to perform intermediate pressure injection for returning the refrigerant to the compression element 21e on the rear stage side of the compression mechanism 21 through the use side injection pipe 94 having the same. That.

  The gas side branch circuit 11e mainly includes a third high-pressure gas refrigerant pipe 71, a plurality (here, two) high-pressure gas refrigerant branch pipes 72 and 73, a low-pressure gas refrigerant pipe 74, and a plurality (here, 2). One) low-pressure gas refrigerant branch pipes 75 and 76 and a plurality (two in this case) of second gas refrigerant branch pipes 77 and 78.

  The third high-pressure gas refrigerant pipe 71 has one end connected to the high-pressure gas refrigerant communication pipe 9 and the other end connected to the high-pressure gas refrigerant branch pipes 72 and 73. Here, a refrigerant pipe composed of the first high-pressure gas refrigerant pipe 31, the second high-pressure gas refrigerant pipe 32, the high-pressure gas refrigerant communication pipe 9 and the third high-pressure gas refrigerant pipe 71 is referred to as a high-pressure gas refrigerant pipe 95.

  One end of the high-pressure gas refrigerant branch pipe 72 is connected to the third high-pressure gas refrigerant pipe 71, and the other end is connected to the second gas refrigerant branch pipe 77. The high-pressure gas refrigerant branch pipe 72 is provided with a high-pressure gas on-off valve 79 so that the refrigerant flowing through the high-pressure gas refrigerant branch pipe 72 can be circulated and shut off. The high-pressure gas on / off valve 79 is composed of an electromagnetic valve.

  The high pressure gas refrigerant branch pipe 73 has one end connected to the third high pressure gas refrigerant pipe 71 and the other end connected to the second gas refrigerant branch pipe 78. The high-pressure gas refrigerant branch pipe 73 is provided with a high-pressure gas on-off valve 80 so that the refrigerant flowing through the high-pressure gas refrigerant branch pipe 73 can be circulated and shut off. The high-pressure gas on / off valve 80 is composed of an electromagnetic valve.

  One end of the low-pressure gas refrigerant pipe 74 is connected to the low-pressure gas refrigerant communication pipe 10, and the other end is connected to the low-pressure gas refrigerant branch pipes 75 and 76. Here, a refrigerant pipe composed of the suction pipe 26, the low-pressure gas refrigerant communication pipe 10 and the low-pressure gas refrigerant pipe 74 is referred to as a low-pressure gas refrigerant pipe 96.

  The low pressure gas refrigerant branch pipe 75 has one end connected to the low pressure gas refrigerant pipe 74 and the other end connected to the second gas refrigerant branch pipe 77. The low-pressure gas refrigerant branch pipe 75 is provided with a low-pressure gas on-off valve 81 so that the refrigerant flowing through the low-pressure gas refrigerant branch pipe 75 can be circulated and shut off. The low pressure gas on / off valve 81 is composed of an electromagnetic valve.

  The low pressure gas refrigerant branch pipe 76 has one end connected to the low pressure gas refrigerant pipe 74 and the other end connected to the second gas refrigerant branch pipe 78. The low-pressure gas refrigerant branch pipe 76 is provided with a low-pressure gas on-off valve 82 so that the refrigerant flowing through the low-pressure gas refrigerant branch pipe 76 can be passed and shut off. The low pressure gas on / off valve 82 is composed of an electromagnetic valve.

  One end of the second gas refrigerant branch pipe 77 is connected to the high-pressure gas refrigerant branch pipe 72 and the low-pressure gas refrigerant branch pipe 75, and the other end is connected to the third gas refrigerant branch pipe 15 corresponding to the usage unit 4. ing. The third gas refrigerant branch pipe 15 is a refrigerant pipe that connects the second gas refrigerant branch pipe 77 of the branch unit 6 and the first gas refrigerant branch pipe 44 of the utilization unit 4. Here, a refrigerant pipe composed of the first gas refrigerant branch pipe 44, the third gas refrigerant branch pipe 15, and the second gas refrigerant branch pipe 77 is referred to as a gas refrigerant branch pipe 97.

  One end of the second gas refrigerant branch pipe 78 is connected to the high pressure gas refrigerant branch pipe 73 and the low pressure gas refrigerant branch pipe 76, and the other end is connected to the third gas refrigerant branch pipe 16 corresponding to the usage unit 5. ing. The third gas refrigerant branch pipe 16 is a refrigerant pipe that connects the second gas refrigerant branch pipe 78 of the branch unit 6 and the first gas refrigerant branch pipe 54 of the utilization unit 5. Here, a refrigerant pipe composed of the first gas refrigerant branch pipe 54, the third gas refrigerant branch pipe 16, and the second gas refrigerant branch pipe 78 is referred to as a gas refrigerant branch pipe 98.

  As described above, the branch unit 6 is provided with the high-pressure gas on-off valve 79 and the low-pressure gas on-off valve 81 as the use side switching mechanism corresponding to the use unit 4, and is used corresponding to the use unit 5. A high pressure gas on / off valve 80 and a low pressure gas on / off valve 82 are provided as side switching mechanisms. When the cooling operation of the usage unit 4 is performed, the high-pressure gas on / off valve 79 is closed and the low-pressure gas on / off valve 81 is opened, so that the refrigerant on the usage side heat exchanger 42 flows through the liquid refrigerant branch pipe 92. It is possible to switch to a cooling operation switching state that functions as an evaporator. When performing heating operation of the utilization unit 4, the high pressure gas on / off valve 79 is opened and the low pressure gas on / off valve 81 is closed. It is possible to switch to the heating operation switching state in which the side heat exchanger 42 functions as a radiator for the refrigerant flowing through the high-pressure gas refrigerant pipe 95. Further, when the cooling operation of the use unit 5 is performed, the high-pressure gas on / off valve 80 is closed and the low-pressure gas on / off valve 82 is opened, so that the use-side heat exchanger 52 is supplied with When switching to the cooling operation switching state for functioning as an evaporator, and when performing heating operation of the use unit 5, the use side heat exchange is performed by opening the high pressure gas on / off valve 80 and closing the low pressure gas on / off valve 82. The heater 52 can be switched to a heating operation switching state in which it functions as a radiator of the refrigerant flowing through the high-pressure gas refrigerant pipe 95.

  As described above, the air conditioner 1 of the present embodiment includes the compression mechanism 21, the heat source side heat exchanger 23, the liquid refrigerant merging pipe 91 connected to the heat source side heat exchanger 23, and the liquid refrigerant merging pipe. 91, heat source side expansion mechanism 24 provided in 91, a plurality (two in this case) of use side heat exchangers 42 and 52, and branching from liquid refrigerant junction pipe 91 to each use side heat exchangers 42 and 52. Liquid refrigerant branch pipes 92 and 93 connected to each other, use side expansion mechanisms 41 and 51 provided in the liquid refrigerant branch pipes 92 and 93, and the heat source side heat exchanger 23 of the refrigerant discharged from the compression mechanism 21 A first switching mechanism as a heat source side switching mechanism capable of switching between a heat radiation operation switching state for functioning as a radiator and an evaporation operation switching state for causing the heat source side heat exchanger 23 to function as an evaporator for refrigerant flowing through the liquid refrigerant junction pipe 91. 22 and the discharge side of the compression mechanism 21 and the first Corresponding to the high-pressure gas refrigerant pipe 95 that is connected to the conversion mechanism 22 and branches before the refrigerant discharged from the compression mechanism 21 flows into the first switching mechanism 22, and the use side heat exchangers 42 and 52. A cooling operation switching state in which the use side heat exchangers 42 and 52 function as an evaporator of the refrigerant flowing through the liquid refrigerant branch pipes 92 and 93 and the use side heat exchangers 42 and 52 are connected to the high pressure gas refrigerant pipe 95. The gas on-off valves 79 to 82 as use side switching mechanisms capable of switching between heating operation switching states for functioning as radiators of the refrigerant flowing through the refrigerant, and refrigerant evaporated in the respective use side heat exchangers 42 and 52 of the compression mechanism 21 And a low-pressure gas refrigerant pipe 96 to be sent to the suction side. The compression mechanism 21 includes a plurality (here, two) of compression elements 21d and 21e, and the refrigerant discharged from the compression element 21d on the front stage of the compression elements 21d and 21e is supplied to the rear stage. The compression element 21e is configured to sequentially compress, and the liquid refrigerant merging pipe 91 branches a part of the refrigerant flowing through the liquid refrigerant merging pipe 91 to return to the subsequent compression element 21e. Are connected, and a heat source side economizer heat exchanger 36 for exchanging heat between the refrigerant flowing through the liquid refrigerant junction pipe 91 and the refrigerant flowing through the heat source side injection pipe 34 is provided. Includes a use side injection pipe 94 (more specifically, a use side injection pipe for branching a part of the refrigerant flowing through the liquid refrigerant branch pipes 92 and 93 and returning the part to the compression element 21e on the rear stage side. The second use side injection pipes 64, 66) constituting the pipe 94 are connected, and heat exchange is performed between the refrigerant flowing through the liquid refrigerant branch pipes 92, 93 and the refrigerant flowing through the corresponding use side injection pipe 94. User-side economizer heat exchangers 68 and 69 are provided. That is, in the air-conditioning apparatus 1 of the present embodiment, a multi-stage compression type (here, two-stage compression type) compression mechanism 21 is employed as the compression mechanism in a configuration capable of simultaneous cooling and heating, and intermediate pressure injection is performed. As a configuration for this purpose, the liquid refrigerant junction pipe 91 is provided with the heat source side injection pipe 34 and the heat source side economizer heat exchanger 36, and the liquid refrigerant branch pipes 92 and 93 are provided with the usage side injection pipes 94 (more specifically, the usage side). The structure which provided the 2nd utilization side injection pipes 64 and 66) which comprise the side injection pipe 94, and the heat source side economizer heat exchangers 68 and 69 is employ | adopted.

  In the air conditioner 1 of the present embodiment, the use side economizer heat exchangers 68 and 69 are provided between the use side heat exchangers 42 and 52 and the use side expansion mechanisms 41 and 51.

  In addition, the air conditioner 1 of this embodiment includes a part of the liquid refrigerant merging pipe 91 (that is, the first liquid refrigerant merging pipe 30), the compression mechanism 21, the heat source side heat exchanger 23, the heat source side injection pipe 34, and Heat source unit 2 including at least the heat source side economizer heat exchanger 36, a plurality of (here, two) use units 4 and 5 including at least the use side heat exchangers 42 and 52, and the heat source of the liquid refrigerant junction pipe 91 A part (namely, the second liquid refrigerant junction pipe 61) different from the part included in the unit 2 and a part (namely, the second liquid refrigerant branch pipe) of the plural (here, two) liquid refrigerant branch pipes 92, 93. Tube 62, 63) and the branch unit 6 including at least the use-side economizer heat exchangers 68, 69 and the liquid refrigerant continuity comprising a portion connecting the heat source unit 2 and the branch unit 6 in the liquid refrigerant junction tube 91. A high pressure gas refrigerant communication pipe 9 comprising a pipe 8, a portion connecting the heat source unit 2 and the branch unit 6 in the high pressure gas refrigerant pipe 95, and a heat source unit 2 and the branch unit 6 in the low pressure gas refrigerant pipe 96. It is comprised by connecting with the low voltage | pressure gas refrigerant communication pipe | tube 10 which consists of a part which connects between.

  Further, in the air conditioner 1 of the present embodiment, the use side economizer heat exchangers 68 and 69 use the refrigerant flowing through the liquid refrigerant branch pipes 92 and 93 and the use side after radiating heat in the corresponding use side heat exchangers 42 and 52. It is a heat exchanger having a flow path that flows so as to oppose the refrigerant flowing through the injection pipe 94 (more specifically, the second usage-side injection pipes 64 and 66 constituting the usage-side injection pipe 94).

(2) Operation | movement of an air conditioning apparatus Next, operation | movement of the air conditioning apparatus 1 of this embodiment is demonstrated.

  The operation mode of the air conditioner 1 of the present embodiment is that the use units 4 and 5 are all heated according to the cooling operation mode for cooling all the use units 4 and 5 and the air conditioning load of each use unit 4 and 5. There are a heating operation mode for heating and a cooling / heating simultaneous operation mode for heating one of the utilization units 4 and 5 while cooling the other.

  Hereinafter, operations in the three operation modes of the air conditioner 1 will be described.

<Cooling operation mode>
When all the usage units 4 and 5 are cooled, the refrigerant circuit 11 of the air conditioning apparatus 1 is configured as shown in FIG. 2 (the flow of refrigerant is indicated by the arrows attached to the refrigerant circuit 11 of FIG. See). Specifically, in the heat source side refrigerant circuit 11c of the heat source unit 2, the first switching mechanism 22 as the heat source side switching mechanism is switched to the heat radiation operation switching state (the state indicated by the solid line of the first switching mechanism 22 in FIG. 2). By switching to, the heat source side heat exchanger 23 is made to function as a refrigerant radiator. Further, the opening degree of the heat source side expansion mechanism 24 is adjusted so as not to depressurize the refrigerant as much as possible (for example, to be in a fully opened state). In the branch unit 6, the high-pressure gas on-off valves 79 and 80 as the use-side switching mechanism are closed and the low-pressure gas on-off valves 81 and 82 are opened, so that the use-side heat exchangers 42 and 52 of the use units 4 and 5 are cooled. The utilization side heat exchangers 42 and 52 of the utilization units 4 and 5 and the suction side of the compression mechanism 21 of the heat source unit 2 are connected via a low-pressure gas refrigerant pipe 96 and the like. ing. Further, by adjusting the opening of the heat source side injection valve 35 so that the refrigerant flows into the heat source side injection pipe 34, intermediate pressure injection by the heat source side injection pipe 34 and the heat source side economizer heat exchanger 36 is performed. Thus, by closing the use side injection valves 65 and 67, intermediate pressure injection by the use side injection pipe 94 and the use side economizer heat exchangers 68 and 69 is not performed. Further, the opening degree of the use side expansion valves 41 and 51 is adjusted according to the cooling load of each use unit 4 and 5.

  In such a configuration of the refrigerant circuit 11, the low-pressure refrigerant in the refrigeration cycle is sucked into the compression mechanism 21 from the suction pipe 26 and compressed to the intermediate pressure in the refrigeration cycle by the compression element 21 d on the front stage side, and then the intermediate refrigerant pipe. 27 is discharged. The intermediate-pressure refrigerant discharged from the front-stage compression element 21d is further cooled by joining with the refrigerant returned from the heat source-side injection pipe 34 to the rear-stage compression element 21e. Next, the intermediate-pressure refrigerant that has joined the refrigerant returning from the heat-source-side injection pipe 34 (that is, the intermediate-pressure injection by the heat-source-side injection pipe 34 and the heat-source-side economizer heat exchanger 36) is performed after the compression element 21d. The air is sucked into the compression element 21e connected to the side, further compressed, and discharged from the compression mechanism 21 to the discharge pipe 28. Here, the high-pressure refrigerant in the refrigeration cycle discharged from the compression mechanism 21 is compressed to a pressure exceeding the critical pressure by the two-stage compression operation by the compression elements 21d and 21e. The high pressure refrigerant discharged from the compression mechanism 21 passes through the first port 22a and the second port 22b of the first switching mechanism 22 and the heat source side gas refrigerant pipe 29, and serves as a heat source side heat exchanger. 23 to dissipate heat. Then, after the refrigerant that has radiated heat in the heat source side heat exchanger 23 passes through the heat source side expansion mechanism 24, a part of the refrigerant is branched to the heat source side injection pipe 34. The refrigerant flowing through the heat source side injection pipe 34 is sent to the heat source side economizer heat exchanger 36 after being reduced to near the intermediate pressure by the heat source side injection valve 35. Further, the refrigerant flowing through the first liquid refrigerant merging pipe 30 constituting the liquid refrigerant merging pipe 91 after branching to the heat source side injection pipe 34 flows into the heat source side economizer heat exchanger 36 and passes through the heat source side injection pipe 34. It is cooled by exchanging heat with the flowing refrigerant. On the other hand, the refrigerant flowing through the heat source side injection pipe 34 is heated and evaporated by exchanging heat with the refrigerant flowing through the first liquid refrigerant merging pipe 30, and is discharged from the compression element 21d on the preceding stage as described above. It will merge with the intermediate pressure refrigerant. Then, the refrigerant cooled in the heat source side economizer heat exchanger 36 is sent from the heat source unit 2 to the branch unit 6 through the liquid refrigerant junction pipe 91. The refrigerant sent to the branch unit 6 is branched to the second liquid refrigerant branch pipes 62 and 63 constituting the liquid refrigerant branch pipes 92 and 93, and then depressurized by the use side expansion mechanisms 41 and 51, so that the low pressure gas is supplied. It becomes a liquid two-phase state. This low-pressure gas-liquid two-phase refrigerant passes through the liquid refrigerant branch pipes 92 and 93 (here, heat exchange in the use-side economizer heat exchangers 68 and 69 is not performed) from the branch unit 6 to the usage unit 4, Sent to 5. The refrigerant sent to the use units 4 and 5 is sent to the use-side heat exchangers 42 and 52 that function as a refrigerant evaporator to evaporate. The refrigerant evaporated in the use side heat exchangers 42 and 52 is sent from the use units 4 and 5 to the branch unit 6 through the gas refrigerant branch pipes 97 and 98. The refrigerant sent to the branch unit 6 is sent from the branch unit 6 to the heat source unit 2 through the low pressure gas on / off valves 81 and 82 and the low pressure gas refrigerant pipe 96. The refrigerant sent to the heat source unit 2 is again sucked into the compression mechanism 21 through the suction pipe 26. In this way, the operation in the cooling operation mode for cooling all of the usage units 4 and 5 is performed.

  As described above, in the air conditioner 1 of the present embodiment, in the configuration capable of simultaneous cooling and heating, the compression mechanism 21 of the multistage compression type (here, the two-stage compression type) is employed as the compression mechanism, and the intermediate pressure injection is performed. The heat source side injection pipe 34 and the heat source side economizer heat exchanger 36 are provided in the liquid refrigerant junction pipe 91, and the liquid side branch pipes 92 and 93 are used on the use side injection pipes 94 (more specifically, Since the configuration in which the second usage side injection pipes 64 and 66) and the heat source side economizer heat exchangers 68 and 69 constituting the usage side injection pipe 94 are provided is adopted in the cooling operation mode, the heat source side injection is performed. A part of the refrigerant flowing through the liquid refrigerant junction pipe 91 is branched by the pipe 34, and the heat source side economizer heat exchanger 36 is Therefore, while cooling the refrigerant flowing through the liquid refrigerant merging pipe 91, the refrigerant flowing through the heat source side injection pipe 34 is heated, and the cooled refrigerant is used as the utilization side heat exchanger 42 by the liquid refrigerant merging pipe 91 and the liquid refrigerant branch pipes 92 and 93. , 52, the heated refrigerant can be returned to the compression element 21e on the rear stage side by the heat source side injection pipe 34. Thus, while performing the cooling operation of the utilization units 4 and 5, the temperature of the refrigerant sucked into the compression element 21e on the rear stage side in the compression mechanism 21 of the multistage compression type (here, the two-stage compression type) can be kept low. It is possible to improve the operation efficiency in the cooling operation mode.

<Heating operation mode>
When heating all the utilization units 4 and 5, the refrigerant circuit 11 of the air conditioning apparatus 1 is configured as shown in FIG. 3 (the flow of the refrigerant is indicated by the arrows attached to the refrigerant circuit 11 of FIG. See). Specifically, in the heat source side refrigerant circuit 11c of the heat source unit 2, the first switching mechanism 22 as the heat source side switching mechanism is switched to the evaporation operation state (the state indicated by the broken line of the first switching mechanism 22 in FIG. 3). By switching to, the heat source side heat exchanger 23 functions as a refrigerant evaporator, and the second switching mechanism 25 is set to the heating load request operation state (the state indicated by the broken line of the second switching mechanism 25 in FIG. 3). By switching, the high-pressure gas refrigerant compressed and discharged by the compression mechanism 21 can be supplied to the utilization units 4 and 5 through the high-pressure gas refrigerant pipe 95 and the like. The opening degree of the heat source side expansion mechanism 24 is adjusted so as to depressurize the refrigerant. In the branch unit 6, the high-pressure gas on-off valves 79 and 80 serving as the use-side switching mechanism are opened and the low-pressure gas on-off valves 81 and 82 are closed, whereby the use-side heat exchangers 42 and 52 of the use units 4 and 5 are cooled. It is designed to function as a radiator. Further, by closing the heat source side injection valve 35, intermediate pressure injection by the heat source side injection pipe 34 and the heat source side economizer heat exchanger 36 is not performed, and the use side injection valves 65 and 67 are connected to the use side injection. By adjusting the opening so that the refrigerant flows through the pipes 64 and 66, intermediate pressure injection by the use side injection pipe 94 and the use side economizer heat exchangers 68 and 69 is performed. Moreover, the opening degree of the use side expansion valves 41 and 51 is adjusted according to the heating load of each use unit 4 and 5.

  In such a configuration of the refrigerant circuit 11, the low-pressure refrigerant in the refrigeration cycle is sucked into the compression mechanism 21 from the suction pipe 26 and compressed to the intermediate pressure in the refrigeration cycle by the compression element 21 d on the front stage side, and then the intermediate refrigerant pipe. 27 is discharged. The intermediate-pressure refrigerant discharged from the front-stage compression element 21d is further cooled by joining with the refrigerant returned from the use-side injection pipe 94 to the rear-stage compression element 21e. Next, the intermediate pressure refrigerant that has merged with the refrigerant returning from the use side injection pipe 94 (that is, the intermediate pressure injection performed by the use side injection pipe 94 and the use side economizer heat exchangers 68 and 69) is compressed by the compression element 21d. The air is sucked into the compression element 21e connected to the rear stage side, further compressed, and discharged from the compression mechanism 21 to the discharge pipe 28. Here, the high-pressure refrigerant in the refrigeration cycle discharged from the compression mechanism 21 is compressed to a pressure exceeding the critical pressure by the two-stage compression operation by the compression elements 21d and 21e. The high-pressure refrigerant discharged from the compression mechanism 21 passes from the heat source unit 2 to the branch unit 6 through the discharge pipe 28 and the high-pressure gas refrigerant pipe 95 (including the first port 25a and the fourth port 25d of the second switching mechanism 25). Sent to. The refrigerant sent to the branch unit 6 is sent from the branch unit 6 to the utilization units 4 and 5 through the high-pressure gas on-off valves 79 and 80 and the gas refrigerant branch pipes 97 and 98. The refrigerant sent to the use units 4 and 5 is sent to the use-side heat exchangers 42 and 52 that function as a refrigerant radiator and dissipates heat. The refrigerant that has radiated heat in the use side heat exchangers 42 and 52 is sent from the use units 4 and 5 to the branch unit 6 through the liquid refrigerant branch pipes 92 and 93. A part of the refrigerant sent to the branching unit 6 is branched to the second usage-side injection pipes 64 and 66 constituting the usage-side injection pipe 94. The refrigerant flowing through the second usage-side injection pipes 64 and 66 is sent to the usage-side economizer heat exchangers 68 and 69 after being reduced to near the intermediate pressure by the usage-side injection valves 65 and 67. The refrigerant flowing through the second liquid refrigerant branch pipes 62 and 63 constituting the liquid refrigerant branch pipes 92 and 93 after branching to the second usage side injection pipes 64 and 66 is used as the usage side economizer heat exchangers 68 and 69. And is cooled by exchanging heat with the refrigerant flowing through the second usage-side injection pipes 64 and 66. On the other hand, the refrigerant flowing through the second usage side injection pipes 64, 66 is heated and evaporated by exchanging heat with the refrigerant flowing through the second liquid refrigerant branch pipes 62, 63, and passes through the usage side injection pipe 94 (here, After the refrigerant flowing through the second usage-side injection pipes 64 and 66 merges in the third usage-side injection pipe 70, through the usage-side injection communication pipe 14 and the first usage-side injection pipe 33), as described above, The intermediate pressure refrigerant discharged from the compression element 21d is joined. Then, the refrigerant cooled in the use-side economizer heat exchangers 68 and 69 passes through the use-side expansion mechanisms 41 and 51, and then merges in the second liquid refrigerant merge pipe 61 constituting the liquid refrigerant merge pipe 91, The liquid refrigerant junction pipe 91 is sent from the branch unit 6 to the heat source unit 2. The refrigerant sent to the heat source unit 2 is sent to the heat source side expansion mechanism 24 through the liquid refrigerant junction pipe 91 (here, heat exchange in the heat source side economizer heat exchanger 36 is not performed), and the heat source side expansion mechanism. The pressure is reduced by 24 and a low-pressure gas-liquid two-phase state is obtained. The low-pressure gas-liquid two-phase refrigerant is sent to the heat source side heat exchanger 23 that functions as a refrigerant evaporator and evaporates. The refrigerant evaporated in the heat source side heat exchanger 23 is again sucked into the compression mechanism 21 through the heat source side gas refrigerant pipe 29, the second port 22 b and the third port 22 c of the first switching mechanism 22, and the suction pipe 26. The Thus, the operation | movement in the heating operation mode which heats all the utilization units 4 and 5 is performed.

  In the above description, by closing the heat source side injection valve 36, the intermediate pressure injection by the heat source side injection pipe 34 and the heat source side economizer heat exchanger 36 is not performed, and the use side injection valves 65 and 67 are set to the use side. By adjusting the opening so that the refrigerant flows through the injection pipes 64 and 66, intermediate pressure injection is performed by the use side injection pipe 94 and the use side economizer heat exchangers 68 and 69. By adjusting the opening of the injection valve 35 so that the refrigerant flows into the heat source side injection pipe 34, intermediate pressure injection by the heat source side injection pipe 34 and the heat source side economizer heat exchanger 36 may also be performed.

  As described above, in the air conditioner 1 of the present embodiment, in the configuration capable of simultaneous cooling and heating, the compression mechanism 21 of the multistage compression type (here, the two-stage compression type) is employed as the compression mechanism, and the intermediate pressure injection is performed. The heat source side injection pipe 34 and the heat source side economizer heat exchanger 36 are provided in the liquid refrigerant junction pipe 91, and the liquid side branch pipes 92 and 93 are used on the use side injection pipes 94 (more specifically, The second use side injection pipes 64 and 66) constituting the use side injection pipe 94 and the heat source side economizer heat exchangers 68 and 69 are adopted, so that the second use is used in the heating operation mode. A part of the refrigerant flowing in the liquid refrigerant branch pipes 92 and 93 is branched by the side injection pipes 64 and 66, and the use side economy While the refrigerant flowing through the liquid refrigerant branch pipes 92 and 93 is cooled by the heat exchangers 68 and 69, the refrigerant flowing through the second usage-side injection pipes 64 and 66 is heated, and the cooled refrigerant is used as the liquid refrigerant branch pipes 92 and 93. In addition, while being sent to the heat source side heat exchanger 23 by the liquid refrigerant junction pipe 91, the heated refrigerant is returned to the compression element 21e on the rear stage side by the use side injection pipe 94, and further, the liquid refrigerant junction pipe by the heat source side injection pipe 34. A part of the refrigerant flowing through 91 is branched, and the refrigerant flowing through the heat source side injection pipe 34 is heated while the refrigerant flowing through the liquid refrigerant merging pipe 91 is cooled by the heat source side economizer heat exchanger 36, and the cooled refrigerant is liquefied. While being sent to the heat source side heat exchanger 23 by the refrigerant junction pipe 91, the heated refrigerant is supplied to the rear stage side by the heat source side injection pipe 34. It can be returned to the condensation element 21e. Thereby, the temperature of the refrigerant sucked into the compression element 21e on the rear stage side in the compression mechanism 21 of the multistage compression type (here, the two-stage compression type) can be kept low while performing the heating operation of the utilization units 4 and 5. It is possible to improve the operation efficiency in the heating operation mode.

<Cooling and heating simultaneous operation mode>
When one of the usage units 4 and 5 is cooled and the other is heated (here, the usage unit 4 is cooled and the usage unit 5 is heated), the refrigerant circuit 11 of the air conditioner 1 is shown in FIG. (Refer to the arrow attached to the refrigerant circuit 11 in FIG. 4 for the refrigerant flow). Specifically, in the heat source side refrigerant circuit 11c of the heat source unit 2, the first switching mechanism 22 serving as the heat source side switching mechanism is radiated according to the balance between the cooling load of the usage unit 4 and the heating load of the usage unit 5. By switching to either the switching state or the evaporation operation switching state, the heat source side heat exchanger 23 functions as a refrigerant radiator or evaporator, and the second switching mechanism 25 is operated in the heating load required operation state (the first state in FIG. 4). By switching to the state shown by the broken line of the two switching mechanism 25, the high-pressure gas refrigerant compressed and discharged in the compression mechanism 21 can be supplied to the utilization unit 5 through the high-pressure gas refrigerant pipe 95 and the like. Further, when the first switching mechanism 22 is in the heat dissipation operation switching state, the heat source side expansion mechanism 24 is adjusted in opening degree so as not to depressurize the refrigerant as much as possible (for example, to be in a fully opened state), and the first switching mechanism When 22 is in the evaporative operation switching state, the opening degree is adjusted so as to depressurize the refrigerant. In the branch unit 6, the high-pressure gas on / off valve 79 serving as the use-side switching mechanism corresponding to the use unit 4 is closed and the low-pressure gas on / off valve 81 is opened, whereby the use-side heat exchanger 42 of the use unit 4 is evaporated. The utilization side heat exchanger 42 of the utilization unit 4 and the suction side of the compression mechanism 21 of the heat source unit 2 are connected via a low-pressure gas refrigerant pipe 96 and the like. Further, by opening the high-pressure gas on-off valve 80 serving as the use-side switching mechanism and closing the low-pressure gas on-off valve 82, the use-side heat exchanger 52 of the use unit 5 functions as a refrigerant radiator. Further, by closing the heat source side injection valve 36, intermediate pressure injection by the heat source side injection pipe 34 and the heat source side economizer heat exchanger 36 is not performed, and the use side injection valves 65 and 67 are connected to the use side injection. By adjusting the opening so that the refrigerant flows through the pipes 64 and 66, intermediate pressure injection by the use side injection pipe 94 and the use side economizer heat exchangers 68 and 69 is performed. The opening degree of the use side expansion valve 41 is adjusted according to the cooling load of the use unit 4, and the opening degree of the use side expansion valve 51 is adjusted according to the heating load of the use unit 5.

  In such a configuration of the refrigerant circuit 11, the low-pressure refrigerant in the refrigeration cycle is sucked into the compression mechanism 21 from the suction pipe 26 and compressed to the intermediate pressure in the refrigeration cycle by the compression element 21 d on the front stage side, and then the intermediate refrigerant pipe. 27 is discharged. The intermediate-pressure refrigerant discharged from the front-stage compression element 21d is further cooled by joining with the gas refrigerant returned from the use-side injection pipe 94 to the rear-stage compression element 21e. Next, the intermediate-pressure refrigerant that has joined with the refrigerant returning from the use-side injection pipe 94 (that is, the intermediate-pressure injection performed by the use-side injection pipe 94 and the use-side economizer heat exchanger 69) is downstream of the compression element 21d. The air is sucked into the compression element 21e connected to the side, further compressed, and discharged from the compression mechanism 21 to the discharge pipe 28. Here, the high-pressure refrigerant in the refrigeration cycle discharged from the compression mechanism 21 is compressed to a pressure exceeding the critical pressure by the two-stage compression operation by the compression elements 21d and 21e. Most of the high-pressure refrigerant discharged from the compression mechanism 21 includes the discharge pipe 28 and the high-pressure gas refrigerant pipe 95 (second switching mechanism), including the case where the first switching mechanism 22 is in the heat radiation operation switching state. 25, including the first port 25a and the fourth port 25d). The refrigerant sent to the branch unit 6 is sent from the branch unit 6 to the utilization unit 5 through the high-pressure gas on-off valve 80 and the gas refrigerant branch pipe 98. The refrigerant sent to the usage unit 5 is sent to the usage-side heat exchanger 52 that functions as a refrigerant radiator to dissipate heat. Then, the refrigerant that has radiated heat in the use side heat exchanger 52 is sent from the use unit 5 to the branch unit 6 through the liquid refrigerant branch pipe 93. A part of the refrigerant sent to the branch unit 6 is branched to a second usage-side injection pipe 66 that constitutes the usage-side injection pipe 94. Then, the refrigerant flowing through the second usage-side injection pipe 66 is sent to the usage-side economizer heat exchanger 69 after being reduced to near the intermediate pressure by the usage-side injection valve 67. In addition, the refrigerant flowing through the second liquid refrigerant branch pipe 63 constituting the liquid refrigerant branch pipe 93 after being branched to the second usage side injection pipe 66 flows into the usage side economizer heat exchanger 69, and the second usage side The refrigerant is cooled by exchanging heat with the refrigerant flowing through the injection pipe 66. On the other hand, the refrigerant flowing through the second usage side injection pipe 66 is heated and evaporated by exchanging heat with the refrigerant flowing through the second liquid refrigerant branch pipe 63, and passes through the usage side injection pipe 94 (here, the second usage side After the refrigerant flowing through the side injection pipe 66 flows into the third usage side injection pipe 70, it is discharged from the compression element 21d on the front stage as described above through the usage side injection connecting pipe 14 and the first usage side injection pipe 33). The resulting intermediate pressure refrigerant is merged. The refrigerant cooled in the use-side economizer heat exchanger 69 passes through the use-side expansion mechanism 51, and then merges with the second liquid refrigerant merge pipe 61 that constitutes the liquid refrigerant merge pipe 91. It is sent to the liquid refrigerant branch pipe 92. The refrigerant sent to the liquid refrigerant branch pipe 92 is decompressed by the use side expansion mechanism 41 to be in a low-pressure gas-liquid two-phase state. This low-pressure gas-liquid two-phase refrigerant is sent from the branch unit 6 to the utilization unit 4 through the liquid refrigerant branch pipe 92 (here, heat exchange in the utilization-side economizer heat exchanger 68 is not performed). The refrigerant sent to the use unit 4 is sent to the use-side heat exchanger 42 that functions as a refrigerant evaporator and evaporates. Then, the refrigerant evaporated in the use side heat exchanger 42 is sent to the branch unit 6 through the gas refrigerant branch pipe 97. The refrigerant sent to the branch unit 6 is sent from the branch unit 6 to the heat source unit 2 through the low pressure gas on-off valve 81 and the low pressure gas refrigerant pipe 96. The refrigerant sent to the heat source unit 2 is again sucked into the compression mechanism 21 through the suction pipe 26. In this manner, the operation in the cooling / heating simultaneous operation mode is performed in which one of the usage units 4 and 5 is cooled while the other is heated (here, the usage unit 4 is cooled and the usage unit 5 is heated).

  In the cooling / heating simultaneous operation mode, as described above, most of the high-pressure refrigerant discharged from the compression mechanism 21 is discharged from the discharge pipe 28 and the high-pressure gas refrigerant pipe 95 (the first port 25a and the second switching mechanism 25). Most of the refrigerant sent from the heat source unit 2 to the branch unit 6 through the fourth port 25d and cooled in the use-side economizer heat exchanger 69 is transferred from the branch unit 6 to the use unit through the liquid refrigerant branch pipe 92. 4, the refrigerant exchanged between the use side heat exchangers 42 and 52 and the heat source side heat exchanger 23 (that is, between the liquid refrigerant branch pipes 92 and 93 and the liquid refrigerant junction pipe 91). (For this reason, in FIG. 4, through the first switching mechanism 22, the heat source side heat exchanger 23, the heat source side expansion mechanism 24, and the liquid refrigerant merging pipe 30, in FIG. The portion extending in the liquid separator 61, are omitted arrows indicating the flow of the refrigerant).

  As described above, in the air conditioner 1 of the present embodiment, in the configuration capable of simultaneous cooling and heating, the compression mechanism 21 of the multistage compression type (here, the two-stage compression type) is employed as the compression mechanism, and the intermediate pressure injection is performed. The heat source side injection pipe 34 and the heat source side economizer heat exchanger 36 are provided in the liquid refrigerant junction pipe 91, and the liquid side branch pipes 92 and 93 are used on the use side injection pipes 94 (more specifically, The second use side injection pipes 64 and 66) constituting the use side injection pipe 94 and the heat source side economizer heat exchangers 68 and 69 are employed, so that in the cooling and heating simultaneous operation mode, the second One of the use side injection pipes 64 and 66 branches a part of the refrigerant flowing through the corresponding liquid refrigerant branch pipes 92 and 93. Then, the corresponding use side economizer heat exchangers 68 and 69 heat and cool the refrigerant flowing through one of the second use side injection pipes 64 and 66 while cooling the refrigerant flowing through the corresponding liquid refrigerant branch pipes 92 and 93. The heated refrigerant can be returned to the compression element 21e on the rear stage side by the use side injection pipe 94 while the supplied refrigerant is sent to the corresponding use side heat exchangers 42, 52 by the other of the liquid refrigerant branch pipes 92, 93. . Thus, while one of the utilization units 4 and 5 is cooled and the other is heated, it is sucked into the compression element 21e on the rear stage side in the compression mechanism 21 of the multistage compression type (here, two-stage compression type). The temperature of the refrigerant can be kept low, and the operation efficiency in the cooling and heating simultaneous operation mode can be improved.

  In addition, when the balance between the cooling load of the usage unit 4 and the heating load of the usage unit 5 is biased in either direction, between the usage side heat exchangers 42 and 52 and the heat source side heat exchanger 23 (that is, Although the flow rate of the refrigerant exchanged between the liquid refrigerant branch pipes 92 and 93 and the liquid refrigerant junction pipe 91 increases, even in such a case, the use-side heat exchanger (for cooling) ( Here, the refrigerant exchanged between the use side heat exchangers 42 and 52) and the use side heat exchanger for heating (here, the other of the use side heat exchangers 42 and 52) is the use side economizer. The refrigerant is exchanged via the heat exchangers 68 and 69, and the refrigerant is passed through the second use side injection pipes 64 and 66 constituting the use side injection pipes 94 corresponding to the use side economizer heat exchangers 42 and 52. of It can be returned to the condensation element 21e. Further, by adjusting the opening of the heat source side injection valve 35 so that the refrigerant flows into the heat source side injection pipe 34, the intermediate pressure injection by the heat source side injection pipe 34 and the heat source side economizer heat exchanger 36 is performed, You may make it use together with the intermediate pressure injection by the use side injection pipe | tube 94 and the use side economizer heat exchanger 68,69.

(3) Features of the air conditioner The air conditioner 1 of the present embodiment has the following features.

<A>
Compression mechanism, heat source side heat exchanger, liquid refrigerant junction pipe, heat source side expansion mechanism, multiple usage side heat exchangers, multiple liquid refrigerant branch pipes, heat source side switching mechanism, high pressure gas refrigerant pipe, and multiple usage side switching mechanisms And a low-pressure gas refrigerant pipe capable of simultaneous cooling and heating, the refrigerant having a plurality of compression elements as a compression mechanism and discharged from the compression element on the front stage among the plurality of compression elements In order to improve the operating efficiency of the multistage compression refrigeration cycle, in the multistage compression refrigeration cycle, the multistage compression type refrigeration cycle is used. A configuration for performing intermediate pressure injection on the liquid side of the heat source side heat exchanger is provided in the same manner as an air conditioner capable of cooling / heating switching operation that performs intermediate pressure injection for returning intermediate pressure refrigerant to the downstream compression element. Rukoto is considered.

  However, in an air conditioner capable of simultaneous cooling and heating, there is a simultaneous cooling and heating operation in which a use side heat exchanger that performs cooling and a use side heat exchanger that performs heating coexist (operation in the above-described cooling and heating simultaneous operation mode and FIG. 4). In this simultaneous cooling and heating operation, refrigerant is mainly exchanged between the use side heat exchanger that performs cooling and the use side heat exchanger that performs heating, and a plurality of use side heat exchangers And the heat source side heat exchanger (that is, between the plurality of liquid refrigerant branch pipes and the liquid refrigerant junction pipe), the flow rate of the refrigerant is reduced. For this reason, in simultaneous cooling and heating operation, it becomes difficult to secure the flow rate of the refrigerant supplied to the intermediate pressure injection, and it becomes difficult to improve the operation efficiency in the multistage compression refrigeration cycle.

  Therefore, in the air conditioner 1 of the present embodiment, the heat source side injection pipe 34 is connected to the liquid refrigerant merging pipe 91 and a part of the refrigerant flowing through the liquid refrigerant merging pipe 91 is branched and returned to the compression element 21e on the rear stage side. The heat source side economizer heat exchanger 36 for performing heat exchange between the refrigerant flowing through the liquid refrigerant junction pipe 91 and the refrigerant flowing through the heat source side injection pipe 34 is provided, and each liquid refrigerant branch pipe 92, 93 is provided with each liquid refrigerant branch pipe 92, 93. Use side injection pipes 94 (particularly, second use side injection pipes 64 and 66 constituting the use side injection pipes 94) for branching a part of the refrigerant flowing through the pipe 93 and returning it to the compression element 21e on the rear stage side. The user-side economies that connect and exchange heat between the refrigerant flowing through the liquid refrigerant branch pipes 92 and 93 and the refrigerant flowing through the corresponding user-side injection pipe 94. And it is provided with a Isa heat exchanger 68.

  Accordingly, during the cooling and heating simultaneous operation, the use side heat exchanger (here, one of the use side heat exchangers 42 and 52) for cooling and the use side heat exchanger (here, use side heat exchange) for heating are used. The refrigerant exchanged with the other of the condensers 42 and 52 is exchanged via the use-side economizer heat exchangers 68 and 69, and the use-side injection corresponding to the use-side economizer heat exchangers 68 and 69. Since it becomes possible to secure the flow rate of the refrigerant supplied to the intermediate pressure injection for returning the refrigerant to the compression element 21e on the rear stage through the pipe 94, the multistage compression type (in this case, the two-stage compression is used in the simultaneous cooling and heating operation). In the multi-stage compression refrigeration cycle, the intermediate pressure injection for returning the intermediate pressure refrigerant to the compression element on the rear stage side can be improved. It is possible to provide an air conditioner capable of simultaneous cooling and heating operation where the configuration of performing.

<B>
In the air conditioner 1 of the present embodiment, the use-side economizer heat exchangers 68 and 69 are provided between the use-side heat exchangers 42 and 52 and the use-side expansion mechanisms 41 and 51, so that the use-side heat exchange is performed. The refrigerant that has passed through the vessels 42 and 52 passes through the use-side economizer heat exchangers 68 and 69 before the refrigerant is decompressed by the use-side expansion mechanisms 41 and 51. The flowing refrigerant will be maintained at a high pressure.

  As a result, the amount of heat exchanged in the use-side economizer heat exchangers 68 and 69 is increased, so that the use-side injection pipe 94 (more specifically, the second use-side injection pipes 64 and 66 constituting the use-side injection pipe 94). The flow rate of the refrigerant flowing through the refrigerant, that is, the flow rate of the refrigerant supplied to the intermediate pressure injection can be increased, and the operation efficiency in the refrigeration cycle of the multi-stage compression type (here, the two-stage compression type) is further improved. Can be achieved.

<C>
In the air conditioner 1 of the present embodiment, the usage-side gas-liquid separator 61 is provided in the branch unit 6 different from the usage units 4 and 5 and the heat source unit 2, and therefore the usage units 4 and 5 and the heat source unit 2. The use-side gas-liquid separator 61 can be added without significantly changing the device configuration.

  Further, as in the present embodiment, when the use-side gas-liquid separator 61 is provided in the branch unit 6 and the heat source unit 2 and the branch unit 6 are connected by the liquid refrigerant communication pipe 8, the liquid refrigerant communication is performed. Since the pipe 8 is often long in length, for example, from the heat source side heat exchanger 23 toward the use side heat exchangers 42 and 52, such as in the cooling operation mode in which only the use side heat exchanger that performs cooling exists. When the flow rate of the refrigerant flowing through the liquid refrigerant merging pipe 91 is large, the pressure loss of the refrigerant flowing through the liquid refrigerant merging pipe 91 from the heat source side heat exchanger 23 toward the use side heat exchangers 42 and 52 tends to increase. It is in.

  However, in the air conditioner 1 of the present embodiment, a part of the refrigerant flowing through the liquid refrigerant merging pipe 91 is branched into a portion included in the heat source unit 2 of the liquid refrigerant merging pipe 91 and returned to the compression element 21e on the rear stage side. Since the side injection pipe 34 is connected and the heat source side economizer heat exchanger 36 that performs heat exchange between the refrigerant flowing through the liquid refrigerant junction pipe 91 and the refrigerant flowing through the heat source side injection pipe 34 is provided, the heat source side heat When the flow rate of the refrigerant flowing through the liquid refrigerant junction pipe 91 from the exchanger 23 toward the use side heat exchangers 42 and 52 is large, before the pressure drop due to the pressure loss in the liquid refrigerant communication pipe 8 occurs, the heat source side Heat exchange in the economizer heat exchanger 36 can be performed, and the flow rate of the refrigerant that can be returned to the compression element 21e on the rear stage side is unlikely to decrease, and intermediate pressure injection is performed. It can be carried out to the minute.

<D>
In the air conditioner 1 of the present embodiment, the usage-side economizer heat exchangers 68 and 69 radiate heat in the corresponding usage-side heat exchangers 42 and 52 and then the refrigerant flowing through the liquid refrigerant branch pipes 92 and 93 and the usage-side injection pipe. 94 (more specifically, the second usage-side injection pipes 64 and 66 constituting the usage-side injection pipe 94) have a flow path that flows so as to face the refrigerant, so that the usage-side economizer heat exchange is performed. The temperature difference between the refrigerants in the containers 68 and 69 can be reduced, whereby the amount of exchange heat can be increased, and the flow rate of the refrigerant supplied to the intermediate pressure injection can be further increased.

(4) Modifications In the case where the use side economizer heat exchangers 68 and 69 are provided in the branch unit 6 as in the above-described embodiment, the use side injection pipe 94 is joined to the heat source side injection pipe 34, When directly connected to the compression element 21e, the use side injection connecting pipe 14 which is a part of the use side injection pipe 94 exists as one of the refrigerant pipes connecting the branch unit 6 and the heat source unit 2, and the heat source The unit 2 and the branch unit 6 are connected to each other through four types of refrigerant pipes: a liquid refrigerant communication pipe 8, a high-pressure gas refrigerant communication pipe 9, a low-pressure gas refrigerant communication pipe 10, and a user-side injection communication pipe 14. turn into.

  Therefore, in this modified example, as shown in FIG. 5, the use side injection pipe 94 (here, the third use side injection pipe 70) is included in the branch unit 6 (here, the third part of the liquid refrigerant junction pipe 91). The second liquid refrigerant junction pipe 61) is connected. The third usage side injection pipe 70 has one end connected to the second liquid refrigerant merging pipe 61 and the other end connected to the second usage side injection pipes 64 and 66.

  Moreover, in this modification, among the liquid refrigerant merging pipe 91 (here, the second liquid refrigerant merging pipe 61), a plurality of positions and a plurality of positions where the usage side injection pipe 94 (herein, the third usage side injection pipe 70) is connected. A liquid pipe opening / closing mechanism 61a is provided in a portion between the (two here) liquid refrigerant branch pipes 92 and 93. The liquid pipe opening / closing mechanism 61a is an opening / closing valve that enables the refrigerant flowing and shutting off through the third usage-side injection pipe 70, and is composed of an electromagnetic valve in this modification.

  Furthermore, in the present modification, unlike the above-described embodiment, the heat source side injection pipe 34 includes the heat source side economizer heat exchanger 36 and the liquid in the liquid refrigerant merging pipe 91 (here, the first liquid refrigerant merging pipe 30). A part of the refrigerant flowing through the liquid refrigerant junction pipe 91 is branched from the part with the refrigerant communication pipe 8.

  As described above, in the air conditioner 1 of the present modification, in the configuration of the above-described embodiment, the use-side injection communication pipe 14 that mainly connects the branch unit 6 and the heat source unit 2 from the use-side injection pipe 94 is omitted. In addition, the third usage side injection pipe 70 as the usage side injection pipe 94 is connected to the second liquid refrigerant junction pipe 61 of the liquid refrigerant junction pipe 91 in the branch unit 6.

  Next, the operation of the air conditioner 1 of the present modification will be described separately for the cooling operation mode, the heating operation mode, and the cooling / heating simultaneous operation mode.

<Cooling operation mode>
When all the usage units 4 and 5 are cooled, the refrigerant circuit 11 of the air conditioner 1 is configured as shown in FIG. 6 (the flow of the refrigerant is indicated by the arrows attached to the refrigerant circuit 11 of FIG. See). Specifically, in the heat source side refrigerant circuit 11c of the heat source unit 2, the first switching mechanism 22 as the heat source side switching mechanism is switched to the heat radiation operation state (the state indicated by the solid line of the first switching mechanism 22 in FIG. 6). By switching to, the heat source side heat exchanger 23 is made to function as a refrigerant radiator. Further, the opening degree of the heat source side expansion mechanism 24 is adjusted so as not to depressurize the refrigerant as much as possible (for example, to be in a fully opened state). In the branch unit 6, the high-pressure gas on-off valves 79 and 80 as the use-side switching mechanism are closed and the low-pressure gas on-off valves 81 and 82 are opened, so that the use-side heat exchangers 42 and 52 of the use units 4 and 5 are cooled. The utilization side heat exchangers 42 and 52 of the utilization units 4 and 5 and the suction side of the compression mechanism 21 of the heat source unit 2 are connected via a low-pressure gas refrigerant pipe 96 and the like. ing. Further, by adjusting the opening of the heat source side injection valve 35 so that the refrigerant flows into the heat source side injection pipe 34, intermediate pressure injection by the heat source side injection pipe 34 and the heat source side economizer heat exchanger 36 is performed. Thus, by closing the use side injection valves 65 and 67, intermediate pressure injection by the use side injection pipe 94 and the use side economizer heat exchangers 68 and 69 is not performed. The liquid pipe opening / closing mechanism 61a is opened. Further, the opening degree of the use side expansion valves 41 and 51 is adjusted according to the cooling load of each use unit 4 and 5.

  In such a configuration of the refrigerant circuit 11, the low-pressure refrigerant in the refrigeration cycle is sucked into the compression mechanism 21 from the suction pipe 26 and compressed to the intermediate pressure in the refrigeration cycle by the compression element 21 d on the front stage side, and then the intermediate refrigerant pipe. 27 is discharged. The intermediate-pressure refrigerant discharged from the front-stage compression element 21d is further cooled by joining with the refrigerant returned from the heat source-side injection pipe 34 to the rear-stage compression element 21e. Next, the intermediate-pressure refrigerant that has joined the refrigerant returning from the heat-source-side injection pipe 34 (that is, the intermediate-pressure injection by the heat-source-side injection pipe 34 and the heat-source-side economizer heat exchanger 36) is performed after the compression element 21d. The air is sucked into the compression element 21e connected to the side, further compressed, and discharged from the compression mechanism 21 to the discharge pipe 28. Here, the high-pressure refrigerant in the refrigeration cycle discharged from the compression mechanism 21 is compressed to a pressure exceeding the critical pressure by the two-stage compression operation by the compression elements 21d and 21e. The high pressure refrigerant discharged from the compression mechanism 21 passes through the first port 22a and the second port 22b of the first switching mechanism 22 and the heat source side gas refrigerant pipe 29, and serves as a heat source side heat exchanger. 23 to dissipate heat. The refrigerant that has radiated heat in the heat source side heat exchanger 23 flows into the heat source side economizer heat exchanger 36 after passing through the heat source side expansion mechanism 24, and flows into the heat source side injection pipe 34 as described later. It is cooled by heat exchange. A part of the refrigerant cooled in the heat source side economizer heat exchanger 36 is branched to the heat source side injection pipe 34. The refrigerant flowing through the heat source side injection pipe 34 is depressurized to near the intermediate pressure in the heat source side injection valve 35, and then sent to the heat source side economizer heat exchanger 36. As described above, the first liquid refrigerant junction pipe 30 is supplied. The refrigerant is heated and evaporated by exchanging heat with the refrigerant flowing through the refrigerant, and, as described above, merges with the intermediate-pressure refrigerant discharged from the preceding compression element 21d. Then, the refrigerant cooled in the heat source side economizer heat exchanger 36 is sent from the heat source unit 2 to the branch unit 6 through the liquid refrigerant junction pipe 91. The refrigerant sent to the branch unit 6 is branched to the second liquid refrigerant branch pipes 62 and 63 constituting the liquid refrigerant branch pipes 92 and 93, and then depressurized by the use side expansion mechanisms 41 and 51, so that the low pressure gas is supplied. It becomes a liquid two-phase state. This low-pressure gas-liquid two-phase refrigerant passes through the liquid refrigerant branch pipes 92 and 93 (here, heat exchange in the use-side economizer heat exchangers 68 and 69 is not performed) from the branch unit 6 to the usage unit 4, Sent to 5. The refrigerant sent to the use units 4 and 5 is sent to the use-side heat exchangers 42 and 52 that function as a refrigerant evaporator to evaporate. The refrigerant evaporated in the use side heat exchangers 42 and 52 is sent from the use units 4 and 5 to the branch unit 6 through the gas refrigerant branch pipes 97 and 98. The refrigerant sent to the branch unit 6 is sent from the branch unit 6 to the heat source unit 2 through the low pressure gas on / off valves 81 and 82 and the low pressure gas refrigerant pipe 96. The refrigerant sent to the heat source unit 2 is again sucked into the compression mechanism 21 through the suction pipe 26. In this way, the operation in the cooling operation mode for cooling all of the usage units 4 and 5 is performed.

  As described above, in the air conditioner 1 of the present modification, a multi-stage compression type (here, two-stage compression type) compression mechanism 21 is employed as the compression mechanism in a configuration that allows simultaneous cooling and heating operation, and intermediate pressure injection. The heat source side injection pipe 34 and the heat source side economizer heat exchanger 36 are provided in the liquid refrigerant junction pipe 91, and the liquid side branch pipes 92 and 93 are used on the use side injection pipes 94 (more specifically, Since the configuration in which the second usage side injection pipes 64 and 66) and the heat source side economizer heat exchangers 68 and 69 constituting the usage side injection pipe 94 are provided is adopted in the cooling operation mode, the heat source side injection is performed. A part of the refrigerant flowing through the liquid refrigerant junction pipe 91 is branched by the pipe 34 to the heat source side economizer heat exchanger 36. Thus, while cooling the refrigerant flowing through the liquid refrigerant merging pipe 91, the refrigerant flowing through the heat source side injection pipe 34 is heated, and the cooled refrigerant is used as the utilization side heat exchanger by the liquid refrigerant merging pipe 91 and the liquid refrigerant branch pipes 92 and 93. While being sent to 42, 52, the heated refrigerant can be returned to the compression element 21 e on the rear stage side by the heat source side injection pipe 34. Thus, while performing the cooling operation of the utilization units 4 and 5, the temperature of the refrigerant sucked into the compression element 21e on the rear stage side in the compression mechanism 21 of the multistage compression type (here, the two-stage compression type) can be kept low. It is possible to improve the operation efficiency in the cooling operation mode.

<Heating operation mode>
When heating all the utilization units 4 and 5, the refrigerant circuit 11 of the air conditioning apparatus 1 is configured as shown in FIG. 7 (the flow of the refrigerant is indicated by the arrows attached to the refrigerant circuit 11 of FIG. See). Specifically, in the heat source side refrigerant circuit 11c of the heat source unit 2, the first switching mechanism 22 as the heat source side switching mechanism is switched to the evaporation operation state (the state indicated by the broken line of the first switching mechanism 22 in FIG. 7). By switching to, the heat source side heat exchanger 23 functions as a refrigerant evaporator, and the second switching mechanism 25 is brought into the heating load request operation state (the state indicated by the broken line of the second switching mechanism 25 in FIG. 7). By switching, the high-pressure gas refrigerant compressed and discharged by the compression mechanism 21 can be supplied to the utilization units 4 and 5 through the high-pressure gas refrigerant pipe 95 and the like. The opening degree of the heat source side expansion mechanism 24 is adjusted so as to depressurize the refrigerant. In the branch unit 6, the high-pressure gas on-off valves 79 and 80 serving as the use-side switching mechanism are opened and the low-pressure gas on-off valves 81 and 82 are closed, whereby the use-side heat exchangers 42 and 52 of the use units 4 and 5 are cooled. It is designed to function as a radiator. Further, by adjusting the opening of the heat source side injection valve 35 so that the refrigerant flows into the heat source side injection pipe 34, intermediate pressure injection by the heat source side injection pipe 34 and the heat source side economizer heat exchanger 36 is performed. Thus, by closing the use side injection valves 65 and 67, intermediate pressure injection by the use side injection pipe 94 and the use side economizer heat exchangers 68 and 69 is not performed. The liquid pipe opening / closing mechanism 61a is opened. Moreover, the opening degree of the use side expansion valves 41 and 51 is adjusted according to the heating load of each use unit 4 and 5.

  In such a configuration of the refrigerant circuit 11, the low-pressure refrigerant in the refrigeration cycle is sucked into the compression mechanism 21 from the suction pipe 26 and compressed to the intermediate pressure in the refrigeration cycle by the compression element 21 d on the front stage side, and then the intermediate refrigerant pipe. 27 is discharged. The intermediate-pressure refrigerant discharged from the front-stage compression element 21d is further cooled by joining with the refrigerant returned from the heat source-side injection pipe 34 to the rear-stage compression element 21e. Next, the intermediate-pressure refrigerant that has joined the refrigerant returning from the heat-source-side injection pipe 34 (that is, the intermediate-pressure injection by the heat-source-side injection pipe 34 and the heat-source-side economizer heat exchanger 36) is performed after the compression element 21d. The air is sucked into the compression element 21e connected to the side, further compressed, and discharged from the compression mechanism 21 to the discharge pipe 28. Here, the high-pressure refrigerant in the refrigeration cycle discharged from the compression mechanism 21 is compressed to a pressure exceeding the critical pressure by the two-stage compression operation by the compression elements 21d and 21e. The high-pressure refrigerant discharged from the compression mechanism 21 passes from the heat source unit 2 to the branch unit 6 through the discharge pipe 28 and the high-pressure gas refrigerant pipe 95 (including the first port 25a and the fourth port 25d of the second switching mechanism 25). Sent to. The refrigerant sent to the branch unit 6 is sent from the branch unit 6 to the utilization units 4 and 5 through the high-pressure gas on-off valves 79 and 80 and the gas refrigerant branch pipes 97 and 98. The refrigerant sent to the use units 4 and 5 is sent to the use-side heat exchangers 42 and 52 that function as a refrigerant radiator and dissipates heat. The refrigerant that has radiated heat in the use side heat exchangers 42 and 52 is sent from the use units 4 and 5 to the branch unit 6 through the liquid refrigerant branch pipes 92 and 93. The refrigerant sent to the branch unit 6 is not subjected to heat exchange in the second liquid refrigerant branch pipes 62 and 63 (here, the use-side economizer heat exchangers 68 and 69 constituting the liquid refrigerant branch pipes 92 and 93, Only through the use-side expansion mechanisms 41 and 51), and merges in the second liquid refrigerant merging pipe 61 constituting the liquid refrigerant merging pipe 91, and is sent from the branch unit 6 to the heat source unit 2 through the liquid refrigerant merging pipe 91. It is done. A part of the refrigerant sent to the heat source unit 2 is branched to the heat source side injection pipe 34. The refrigerant flowing through the heat source side injection pipe 34 is sent to the heat source side economizer heat exchanger 36 after being reduced to near the intermediate pressure by the heat source side injection valve 35. Further, the refrigerant flowing through the first liquid refrigerant merging pipe 30 constituting the liquid refrigerant merging pipe 91 after branching to the heat source side injection pipe 34 flows into the heat source side economizer heat exchanger 36 and passes through the heat source side injection pipe 34. It is cooled by exchanging heat with the flowing refrigerant. On the other hand, the refrigerant flowing through the heat source side injection pipe 34 is heated and evaporated by exchanging heat with the refrigerant flowing through the first liquid refrigerant merging pipe 30, and is discharged from the compression element 21d on the preceding stage as described above. It will merge with the intermediate pressure refrigerant. Then, the refrigerant cooled in the heat source side economizer heat exchanger 36 is sent to the heat source side expansion mechanism 24 through the liquid refrigerant junction pipe 91, and is decompressed by the heat source side expansion mechanism 24 to be in a low-pressure gas-liquid two-phase state. . The low-pressure gas-liquid two-phase refrigerant is sent to the heat source side heat exchanger 23 that functions as a refrigerant evaporator and evaporates. The refrigerant evaporated in the heat source side heat exchanger 23 is again sucked into the compression mechanism 21 through the heat source side gas refrigerant pipe 29, the second port 22 b and the third port 22 c of the first switching mechanism 22, and the suction pipe 26. The Thus, the operation | movement in the heating operation mode which heats all the utilization units 4 and 5 is performed.

  As described above, in the air conditioner 1 of the present embodiment, in the configuration capable of simultaneous cooling and heating, the compression mechanism 21 of the multistage compression type (here, the two-stage compression type) is employed as the compression mechanism, and intermediate pressure injection The heat source side injection pipe 34 and the heat source side economizer heat exchanger 36 are provided in the liquid refrigerant junction pipe 91, and the liquid side branch pipes 92 and 93 are used on the use side injection pipes 94 (more specifically, Since the configuration in which the second use side injection pipes 64, 66) and the heat source side economizer heat exchangers 68, 69 constituting the use side injection pipe 94 are provided is adopted, in the heating operation mode, the heat source side injection is performed. A part of the refrigerant flowing through the liquid refrigerant junction pipe 91 is branched by the pipe 34, and the heat source side economizer heat exchanger 36 is branched. Therefore, the refrigerant flowing through the heat source side injection pipe 34 is heated while cooling the refrigerant flowing through the liquid refrigerant junction pipe 91, and the cooled refrigerant is sent to the heat source side heat exchanger 23 through the liquid refrigerant junction pipe 91 while being heated. Can be returned to the compression element 21e on the rear stage side by the heat source side injection pipe 34. Thereby, the temperature of the refrigerant sucked into the compression element 21e on the rear stage side in the compression mechanism 21 of the multistage compression type (here, the two-stage compression type) can be kept low while performing the heating operation of the utilization units 4 and 5. It is possible to improve the operation efficiency in the heating operation mode.

<Cooling and heating simultaneous operation mode>
When one of the usage units 4 and 5 is cooled and the other is heated (here, the usage unit 4 is cooled and the usage unit 5 is heated), the refrigerant circuit 11 of the air conditioner 1 is shown in FIG. (Refer to the arrow attached to the refrigerant circuit 11 in FIG. 8 for the refrigerant flow). Specifically, in the heat source side refrigerant circuit 11c of the heat source unit 2, the first switching mechanism 22 serving as the heat source side switching mechanism is radiated according to the balance between the cooling load of the usage unit 4 and the heating load of the usage unit 5. By switching to either the switching state or the evaporation operation switching state, the heat source side heat exchanger 23 functions as a refrigerant radiator or evaporator, and the second switching mechanism 25 is operated in the heating load required operation state (the first state in FIG. 8). By switching to the state shown by the broken line of the two switching mechanism 25, the high-pressure gas refrigerant compressed and discharged in the compression mechanism 21 can be supplied to the utilization unit 5 through the high-pressure gas refrigerant pipe 95 and the like. The heat source side expansion mechanism 24 is closed. In the branch unit 6, the high-pressure gas on / off valve 79 serving as the use-side switching mechanism corresponding to the use unit 4 is closed and the low-pressure gas on / off valve 81 is opened, whereby the use-side heat exchanger 42 of the use unit 4 is evaporated. The utilization side heat exchanger 42 of the utilization unit 4 and the suction side of the compression mechanism 21 of the heat source unit 2 are connected via a low-pressure gas refrigerant pipe 96 and the like. Further, by opening the high-pressure gas on-off valve 80 serving as the use-side switching mechanism and closing the low-pressure gas on-off valve 82, the use-side heat exchanger 52 of the use unit 5 functions as a refrigerant radiator. Further, by adjusting the opening of the use side injection valves 65 and 67 so that the refrigerant flows into the use side injection pipes 64 and 66, intermediate pressure injection by the use side injection pipe 94 and the use side economizer heat exchangers 68 and 69 is performed. It is in a state to be performed. Further, the heat source side injection valve 36 is opened, and the liquid pipe opening / closing mechanism 61a is closed. The opening degree of the use side expansion valve 41 is adjusted according to the cooling load of the use unit 4, and the opening degree of the use side expansion valve 51 is adjusted according to the heating load of the use unit 5.

  In such a configuration of the refrigerant circuit 11, the low-pressure refrigerant in the refrigeration cycle is sucked into the compression mechanism 21 from the suction pipe 26 and compressed to the intermediate pressure in the refrigeration cycle by the compression element 21 d on the front stage side, and then the intermediate refrigerant pipe. 27 is discharged. The intermediate-pressure refrigerant discharged from the preceding-stage compression element 21d flows from the use side injection pipe 94 (here, the second use side injection pipe 66 and the third use side injection pipe 70) to the liquid refrigerant confluence pipe 91 (here. Then, through the second liquid refrigerant junction pipe 61, the liquid refrigerant communication pipe 8, the first liquid refrigerant junction pipe 30, and the heat source side injection pipe 34), the refrigerant is further cooled by joining with the gas refrigerant returned to the compression element 21e on the rear stage side. Is done. Next, the intermediate-pressure refrigerant that has joined with the refrigerant returning from the use-side injection pipe 94 (that is, the intermediate-pressure injection performed by the use-side injection pipe 94 and the use-side economizer heat exchanger 69) is downstream of the compression element 21d. The air is sucked into the compression element 21e connected to the side, further compressed, and discharged from the compression mechanism 21 to the discharge pipe 28. Here, the high-pressure refrigerant in the refrigeration cycle discharged from the compression mechanism 21 is compressed to a pressure exceeding the critical pressure by the two-stage compression operation by the compression elements 21d and 21e. Most of the high-pressure refrigerant discharged from the compression mechanism 21 includes the discharge pipe 28 and the high-pressure gas refrigerant pipe 95 (second switching mechanism), including the case where the first switching mechanism 22 is in the heat radiation operation switching state. 25, including the first port 25a and the fourth port 25d). The refrigerant sent to the branch unit 6 is sent from the branch unit 6 to the utilization unit 5 through the high-pressure gas on-off valve 80 and the gas refrigerant branch pipe 98. The refrigerant sent to the usage unit 5 is sent to the usage-side heat exchanger 52 that functions as a refrigerant radiator to dissipate heat. Then, the refrigerant that has radiated heat in the use side heat exchanger 52 is sent from the use unit 5 to the branch unit 6 through the liquid refrigerant branch pipe 93. A part of the refrigerant sent to the branch unit 6 is branched to a second usage-side injection pipe 66 that constitutes the usage-side injection pipe 94. Then, the refrigerant flowing through the second usage-side injection pipe 66 is sent to the usage-side economizer heat exchanger 69 after being reduced to near the intermediate pressure by the usage-side injection valve 67. In addition, the refrigerant flowing through the second liquid refrigerant branch pipe 63 constituting the liquid refrigerant branch pipe 93 after being branched to the second usage side injection pipe 66 flows into the usage side economizer heat exchanger 69, and the second usage side The refrigerant is cooled by exchanging heat with the refrigerant flowing through the injection pipe 66. On the other hand, the refrigerant flowing through the second usage-side injection pipe 66 is heated and evaporated by exchanging heat with the refrigerant flowing through the second liquid refrigerant branch pipe 63, and as described above, the usage-side injection pipe 94 (here, The second use side injection pipe 66 and the third use side injection pipe 70), the liquid refrigerant joining pipe 91 and the heat source side injection pipe 34 to join the intermediate pressure refrigerant discharged from the preceding compression element 21 d. Become. The refrigerant cooled in the use side economizer heat exchanger 69 is sent to the liquid refrigerant branch pipe 92 after passing through the use side expansion mechanism 51. The refrigerant sent to the liquid refrigerant branch pipe 92 is decompressed by the use side expansion mechanism 41 to be in a low-pressure gas-liquid two-phase state. This low-pressure gas-liquid two-phase refrigerant is sent from the branch unit 6 to the utilization unit 4 through the liquid refrigerant branch pipe 92 (here, heat exchange in the utilization-side economizer heat exchanger 68 is not performed). The refrigerant sent to the use unit 4 is sent to the use-side heat exchanger 42 that functions as a refrigerant evaporator and evaporates. Then, the refrigerant evaporated in the use side heat exchanger 42 is sent to the branch unit 6 through the gas refrigerant branch pipe 97. The refrigerant sent to the branch unit 6 is sent from the branch unit 6 to the heat source unit 2 through the low pressure gas on-off valve 81 and the low pressure gas refrigerant pipe 96. The refrigerant sent to the heat source unit 2 is again sucked into the compression mechanism 21 through the suction pipe 26. In this manner, the operation in the cooling / heating simultaneous operation mode is performed in which one of the usage units 4 and 5 is cooled while the other is heated (here, the usage unit 4 is cooled and the usage unit 5 is heated).

  That is, in the simultaneous cooling and heating operation mode, most of the high-pressure refrigerant discharged from the compression mechanism 21 is discharged from the discharge pipe 28 and the high-pressure gas refrigerant pipe 95 (the first port 25a and the fourth port 25d of the second switching mechanism 25). Most of the refrigerant sent from the heat source unit 2 to the branch unit 6 and cooled in the use-side economizer heat exchangers 68 and 69 is sent from the branch unit 6 to the use unit 4 through the liquid refrigerant branch pipe 92. Therefore, the flow rate of the refrigerant exchanged between the use side heat exchangers 42 and 52 and the heat source side heat exchanger 23 (that is, between the liquid refrigerant branch pipes 92 and 93 and the liquid refrigerant junction pipe 91) is Therefore, by utilizing this, the liquid refrigerant merging pipe 91 (here, the second liquid refrigerant merging pipe 61, the liquid refrigerant connecting pipe 8, and the first liquid refrigerant merging pipe 30) is used. And so as to function as a tio down communication pipe.

  As described above, in the air conditioner 1 of the present modification, a multi-stage compression type (here, two-stage compression type) compression mechanism 21 is employed as the compression mechanism in a configuration that allows simultaneous cooling and heating operation, and intermediate pressure injection. The heat source side injection pipe 34 and the heat source side economizer heat exchanger 36 are provided in the liquid refrigerant junction pipe 91, and the liquid side branch pipes 92 and 93 are used on the use side injection pipes 94 (more specifically, The second use side injection pipes 64 and 66) constituting the use side injection pipe 94 and the heat source side economizer heat exchangers 68 and 69 are employed, so that in the cooling and heating simultaneous operation mode, the second One of the use side injection pipes 64 and 66 branches a part of the refrigerant flowing through the corresponding liquid refrigerant branch pipes 92 and 93. The corresponding user-side economizer heat exchangers 68 and 69 heat and cool the refrigerant flowing through one of the second user-side injection pipes 64 and 66 while cooling the refrigerant flowing through the corresponding liquid refrigerant branch pipes 92 and 93. The heated refrigerant can be returned to the compression element 21e on the rear stage side by the use side injection pipe 94 while sending the refrigerant to the corresponding use side heat exchangers 42, 52 by the other of the liquid refrigerant branch pipes 92, 93. Thus, while one of the utilization units 4 and 5 is cooled and the other is heated, it is sucked into the compression element 21e on the rear stage side in the compression mechanism 21 of the multistage compression type (here, two-stage compression type). The temperature of the refrigerant can be kept low, and the operation efficiency in the cooling and heating simultaneous operation mode can be improved.

  In addition, in the air conditioner 1 of the present modification, the portion of the liquid refrigerant junction tube 91 in which the usage side injection pipe 94 (here, the third usage side injection pipe 70) is included in the branch unit 6 (here, the second side). Since it is connected to the liquid refrigerant junction pipe 61), it is between the use side heat exchangers 42 and 52 and the heat source side heat exchanger 23 (that is, between the liquid refrigerant junction pipe 91 and the liquid refrigerant branch pipes 92 and 93. ), It is possible to perform intermediate pressure injection by sending the refrigerant flowing through the use side injection pipe 94 to the heat source unit 2 through the liquid refrigerant junction pipe 91 without exchanging the refrigerant. It is possible to adopt a device configuration that does not require the user-side injection communication pipe 14 that has been provided.

  Further, in the air conditioner 1 of the present modification, the use side injection pipe 94 (here, the third use side injection pipe 70) of the liquid refrigerant merging pipe 91 (here, the second liquid refrigerant merging pipe 61) is connected. Since the liquid pipe opening / closing mechanism 61a is provided in a portion between the position where the liquid refrigerant branch pipes 92 and 93 branch to the plurality of positions (two in this case), the liquid refrigerant branch pipes 92 and 93 flow through the use-side injection pipe 94. When the refrigerant is sent to the heat source unit 2 through the liquid refrigerant junction pipe 91, the refrigerant other than the refrigerant supplied to the intermediate pressure injection flows through the use-side injection pipe 94 without flowing out from the plurality of liquid refrigerant branch pipes 92 and 93. The refrigerant can be sent to the heat source unit 2 through the liquid refrigerant junction pipe 91 to perform intermediate pressure injection.

  Furthermore, in the air conditioner 1 of the present modification, unlike the above-described embodiment, the heat source side injection pipe 34 is the heat source side economizer heat in the liquid refrigerant merging pipe 91 (here, the first liquid refrigerant merging pipe 30). Since a part of the refrigerant flowing through the liquid refrigerant merging pipe 91 is branched from the portion of the exchanger 36 and the liquid refrigerant communication pipe 8, the heat source unit 2 is connected from the use side injection pipe 94 through the liquid refrigerant merging pipe 91. Can be supplied to the intermediate pressure injection without passing through the heat source side economizer heat exchanger 36, and as a result, compared with the case where the gas refrigerant passes through the heat source side economizer heat exchanger 36, the intermediate pressure can be supplied. The pressure loss of the gas refrigerant provided for injection can be reduced.

  As described above, in the air conditioner 1 of the present modification, the same effect as the above-described embodiment can be obtained in the cooling / heating simultaneous operation and the cooling operation, and the refrigerant is almost exchanged in the cooling / heating simultaneous operation. By using the non-liquid refrigerant junction pipe 91 as a communication pipe for sending the refrigerant flowing through the use-side injection pipe 94 from the branch unit 6 to the heat source unit 2, the use-side injection connection pipe provided in the above-described embodiment. 14 can be obtained.

(5) Other Embodiments Although the embodiments of the present invention and the modifications thereof have been described with reference to the drawings, the specific configuration is not limited to these embodiments and the modifications thereof, and Changes can be made without departing from the scope of the invention.

<A>
In the above-described embodiment and its modification, a single-shaft two-stage compression compressor in which the two compression elements 21d and 21e are integrated is adopted as the compression mechanism 21, but the present invention is not limited to this. A compressor in which a plurality of compression elements are integrated or a single compression element is incorporated, such as a multistage compression compressor having multiple stages or a single stage compression compressor A plurality of compressors and / or compressors incorporating a plurality of compression elements may be connected. In addition, two or more compressors may be connected in parallel according to the number of units used.

<B>
In the above-described embodiment and its modification, there are two usage units, but the present invention is not limited to this, and there may be three or more.

<C>
In the above-described embodiment and its modification, the branch unit 6 includes the use-side injection pipes 64 and 66, the use-side economizer heat exchangers 68 and 69, the use-side switching mechanism (gas on-off valves 79 to 82), and the surrounding piping. All of them are grouped as one unit, but for each of the usage units 4 and 5, that is, the usage-side injection pipe 64, the usage-side economizer heat exchanger 68, the usage-side switching mechanism (gas on-off valves 79 and 81) and its Unit for usage unit 4 including peripheral piping, usage side injection pipe 66, usage side economizer heat exchanger 69, usage side switching mechanism (gas on / off valves 80, 82) and unit for usage unit 5 including its peripheral piping You may make it divide into. Moreover, you may make it divide into the unit containing the liquid side branch circuit 11d, and the unit containing the gas side branch circuit 11e.

  By using the present invention, it is possible to provide an air conditioner capable of simultaneous cooling and heating that employs a configuration in which intermediate pressure injection is performed to return an intermediate pressure refrigerant to a compression element on the rear stage side in a multistage compression refrigeration cycle. .

It is a schematic block diagram of the air conditioning apparatus concerning one Embodiment of this invention. It is a schematic refrigerant circuit diagram explaining the operation in the cooling operation mode. It is a schematic refrigerant circuit diagram explaining operation | movement of heating operation mode. It is a schematic refrigerant circuit diagram explaining the operation in the cooling and heating simultaneous operation mode. It is a schematic block diagram of the air conditioning apparatus concerning a modification. It is a schematic refrigerant circuit diagram explaining the operation | movement of the air_conditionaing | cooling operation mode in a modification. It is a schematic refrigerant circuit diagram explaining operation | movement of the heating operation mode in a modification. It is a schematic refrigerant circuit diagram explaining the operation in the cooling and heating simultaneous operation mode in the modification.

DESCRIPTION OF SYMBOLS 1 Air conditioning apparatus 2 Heat source unit 4, 5 Use unit 6 Branch unit 8 Liquid refrigerant communication pipe 9 High-pressure gas refrigerant communication pipe 10 Low-pressure gas refrigerant communication pipe 21 Compression mechanism 22 1st switching mechanism (heat source side switching mechanism)
23 heat source side heat exchanger 24 heat source side expansion mechanism 34 heat source side injection pipe 36 heat source side economizer heat exchanger 41, 51 use side expansion mechanism 42, 52 use side heat exchanger 94 use side injection pipe 68, 69 use side economizer heat Exchanger 61a Liquid pipe opening / closing mechanism 79-82 Gas switching valve (use side switching mechanism)
91 Liquid refrigerant junction pipe 92, 93 Liquid refrigerant branch pipe 95 High-pressure gas refrigerant pipe 96 Low-pressure gas refrigerant pipe

Claims (7)

A compression mechanism (21);
A heat source side heat exchanger (23);
A liquid refrigerant junction pipe (91) connected to the heat source side heat exchanger;
A heat source side expansion mechanism (24) provided in the liquid refrigerant junction pipe;
A plurality of use side heat exchangers (42, 52);
Liquid refrigerant branch pipes (92, 93) branched from the liquid refrigerant junction pipe and connected to the respective use side heat exchangers;
A use side expansion mechanism (41, 51) provided in each liquid refrigerant branch pipe;
A heat dissipation operation switching state in which the heat source side heat exchanger functions as a radiator for the refrigerant discharged from the compression mechanism, and an evaporation operation switching in which the heat source side heat exchanger functions as an evaporator for the refrigerant flowing through the liquid refrigerant junction pipe. A heat source side switching mechanism (22) capable of switching between states;
A high-pressure gas refrigerant pipe (95) connected between the discharge side of the compression mechanism and the heat source side switching mechanism and branching before the refrigerant discharged from the compression mechanism flows into the heat source side switching mechanism; ,
A cooling operation switching state is provided corresponding to each use side heat exchanger, and the use side heat exchanger functions as an evaporator of the refrigerant flowing through the liquid refrigerant branch pipe, and the use side heat exchanger has a high pressure. A use side switching mechanism (79 to 82) capable of switching between a heating operation switching state to function as a radiator of the refrigerant flowing through the gas refrigerant pipe;
A low-pressure gas refrigerant pipe (96) for sending the refrigerant evaporated in each use side heat exchanger to the suction side of the compression mechanism,
The compression mechanism has a plurality of compression elements, and is configured to sequentially compress the refrigerant discharged from the front-stage compression elements of the plurality of compression elements by the rear-stage compression elements,
The liquid refrigerant merging pipe is connected to a heat source side injection pipe (34) for branching a part of the refrigerant flowing through the liquid refrigerant merging pipe and returning it to the compression element on the rear stage side. A heat source side economizer heat exchanger (36) for performing heat exchange between the flowing refrigerant and the refrigerant flowing through the heat source side injection pipe is provided;
Each liquid refrigerant branch pipe is connected to a use side injection pipe (94) for branching a part of the refrigerant flowing through each liquid refrigerant branch pipe and returning it to the compression element on the rear stage side. Use side economizer heat exchangers (68, 69) that perform heat exchange between the refrigerant flowing through the branch pipe and the refrigerant flowing through the corresponding use side injection pipe are provided ,
A heat source unit (2) including at least a part of the liquid refrigerant junction pipe, the compression mechanism, the heat source side heat exchanger, the heat source side injection pipe, and the heat source side economizer heat exchanger, and the use side heat exchanger A plurality of use units (4, 5) including at least a part of the liquid refrigerant branch pipe that is different from a part included in the heat source unit and a branch unit (6) including at least the use-side economizer heat exchanger A liquid refrigerant communication pipe (8) comprising a portion connecting the heat source unit and the branch unit in the liquid refrigerant junction pipe, and between the heat source unit and the branch unit in the high-pressure gas refrigerant pipe. From the portion connecting the heat source unit and the branch unit in the low-pressure gas refrigerant tube and the high-pressure gas refrigerant communication tube (9) composed of a portion connecting the two That is configured by the low-pressure gas refrigerant communication pipe (10) and is connected,
The use side injection pipe is connected to a portion included in the branch unit in the liquid refrigerant junction pipe,
When performing only the cooling operation in which the use side heat exchanger functions as a refrigerant evaporator, or when performing only the heating operation in which the use side heat exchanger functions as a refrigerant radiator, the heat source side injection Branching a part of the refrigerant flowing through the liquid refrigerant merging pipe by the pipe, heating the refrigerant flowing through the heat source side injection pipe while cooling the refrigerant flowing through the liquid refrigerant merging pipe by the heat source side economizer heat exchanger, Return the refrigerant flowing through the heated heat source side injection pipe to the compression element on the rear stage side,
When the cooling operation and the heating operation are mixed, a part of the refrigerant flowing through the corresponding liquid refrigerant branch pipe is branched by the use side injection pipe, and the corresponding use side economizer heat exchanger The refrigerant flowing through the use side injection pipe is heated while cooling the refrigerant flowing through the liquid refrigerant branch pipe, and the refrigerant flowing through the heated use side injection pipe is passed through the liquid refrigerant junction pipe and the heat source side injection pipe. Return to the compression element on the rear stage side,
Air conditioner (1).   The said use side economizer heat exchanger (68, 69) is provided between the said use side heat exchanger (42, 52) and the said use side expansion | swelling mechanism (41, 51). Air conditioner (1). Between the position where the use side injection pipe (94) is connected in the liquid refrigerant merging pipe (91) and a branching portion from the liquid refrigerant merging pipe to the liquid refrigerant branch pipes (92, 93). The air conditioner according to claim 1 or 2 , wherein the portion is provided with a liquid pipe opening / closing mechanism (61a). The heat source side injection pipe (34) flows through the liquid refrigerant merging pipe from a part of the heat source side economizer heat exchanger (36) and the liquid refrigerant communication pipe (8) in the liquid refrigerant merging pipe (91). The air conditioner (1) according to any one of claims 1 to 3, wherein the air conditioner (1) is connected so as to branch a part of the refrigerant. The usage-side economizer heat exchangers (68, 69) are arranged such that the refrigerant flowing through the liquid refrigerant branch pipes (92, 93) after radiating heat in the corresponding usage-side heat exchangers (42, 52) and the usage-side injection pipes. The air conditioner (1) according to any one of claims 1 to 4 , wherein the air conditioner (1) is a heat exchanger having a flow path that flows so as to face a refrigerant flowing through (94). The air conditioner (1) according to any one of claims 1 to 5 , wherein the compression mechanism (21) compresses the refrigerant to a pressure exceeding a critical pressure. The air conditioner (1) according to claim 6 , wherein the refrigerant is carbon dioxide.

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