JP2013064543A - Air conditioner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an air conditioner capable of preventing liquid refrigerant accumulated in an outdoor heat exchanger of a stopped outdoor unit from collecting in an operated outdoor unit and overflowing from an accumulator of the outdoor unit, in switching from a cooling operation or a cooling-based operation to a heating operation or a heating-based operation.SOLUTION: In the outdoor unit including a compressor 21a, the outdoor heat exchanger 23a, a four-way valve 22a connected to one end of the outdoor heat exchanger and switching connection to a refrigerant outlet or a refrigerant inlet of the compressor, and the accumulator 24a, a connection port of the outdoor heat exchanger and a connection pipe is positioned higher than a connection port of the accumulator and a connection pipe, with respect to the connection pipe 36a and the connection pipe 37a connecting the outdoor heat exchanger and the accumulator.

Description

  The present invention relates to an air conditioner in which a plurality of outdoor units and a plurality of indoor units are connected in parallel by refrigerant pipes, and more specifically, an air conditioner that prevents refrigerant concentration on an operating outdoor unit. About.

  Conventionally, an air conditioner in which a plurality of outdoor units and a plurality of indoor units are connected by a plurality of refrigerant pipes is known. In such an air conditioner, a plurality of outdoor units and a plurality of indoor units are connected to each other by three refrigerant pipes of a high pressure gas pipe, a low pressure gas pipe, and a liquid pipe. A so-called cooling / heating-free operation can be performed in which the operation and the heating operation can be selected (see, for example, Patent Document 1).

  An air conditioner described in Patent Document 1 includes a compressor, an outdoor heat exchanger, a flow path switching means such as a three-way valve or a four-way valve, an outdoor expansion valve, and a plurality of outdoor units including an accumulator, A plurality of indoor units provided with an indoor heat exchanger and an indoor expansion valve; and a plurality of branch units provided corresponding to the plurality of indoor units and switching the refrigerant flow path in response to switching of the flow path switching means. As described above, they are connected to each other by refrigerant pipes such as a high pressure gas pipe, a low pressure gas pipe and a liquid pipe.

  In such an air conditioner, when all the indoor units are performing the cooling operation, the capacity required for the indoor unit performing the cooling operation is more than the capacity required for the indoor unit performing the heating operation. Is larger (cooling-dominated operation), an outdoor heat exchanger is used as a condenser. In addition, when all indoor units are performing a heating operation, or when the capacity required for an indoor unit performing a heating operation is greater than the capacity required for an indoor unit performing a cooling operation (heating main Operation) uses an outdoor heat exchanger as the evaporator.

  In this type of air conditioner, the number of outdoor units to be operated is determined in accordance with the total operating capacity required for each indoor unit being operated. When switching between cooling operation (or cooling-main operation) and heating operation (or heating-main operation) occurs, not only when all outdoor units are operating, but also the operation capacity required for each indoor unit Even when some of the plurality of outdoor units are operated and the other outdoor units are stopped, the flow path switching means of all the outdoor units is switched in the same manner.

  Specifically, when switching from cooling operation (or cooling main operation) to heating operation (or heating main operation), the outdoor heat exchanger of each outdoor unit functions as an evaporator from a state where it functions as a condenser. Thus, the flow path switching means is switched. In addition, when switching from heating operation (or heating main operation) to cooling operation (or cooling main operation), the outdoor heat exchanger of each outdoor unit changes from a state functioning as an evaporator to a state functioning as a condenser. The flow path switching means is switched.

JP 2003-130492 A (page 4, FIG. 2)

  In the air conditioner as described above, when there is an outdoor unit that does not have a driven compressor among a plurality of outdoor units, the cooling operation (or cooling main operation) is changed to the heating operation (or heating main operation). When switching, that is, when switching the outdoor heat exchanger of each outdoor unit from the state functioning as a condenser to the state functioning as an evaporator, the outdoor heat exchanger of the outdoor unit that does not have a driven compressor flows. It is connected to the compressor (the suction side) of an outdoor unit equipped with a compressor driven via a path switching means and a low-pressure gas pipe. Therefore, a refrigerant that stays when an outdoor heat exchanger provided in an outdoor unit that does not have a driven compressor functions as a condenser and does not evaporate when switching to function as an evaporator. (Hereinafter, the liquid refrigerant staying in the outdoor heat exchanger) is drawn into the outdoor unit equipped with the compressor driven through the low-pressure gas pipe, and concentrated on the accumulator of the outdoor unit. There was a risk of overflow. If an overflow occurs in an accumulator of an outdoor unit equipped with a compressor that is being driven, liquid refrigerant is sucked into the compressor, liquid compression occurs, and the compressor may be damaged.

  The present invention solves the above-described problems, and when switching from cooling operation (or cooling main operation) to heating operation (or heating main operation), the outdoor unit of an outdoor unit that does not have a driven compressor exists. An object of the present invention is to provide an air conditioner that prevents liquid refrigerant staying in a heat exchanger from concentrating on an outdoor unit equipped with a driving compressor and causing overflow in the accumulator of the outdoor unit. And

  In order to solve the above-described problems, an air conditioner of the present invention is connected to one end of a compressor, an outdoor heat exchanger, and an outdoor heat exchanger, and exchanges outdoor heat to a refrigerant discharge port or a refrigerant suction port of the compressor. A plurality of outdoor units provided with flow path switching means and accumulators for switching the connection of the devices, and a plurality of indoor units connected to the plurality of outdoor units in parallel by a high pressure gas pipe, a low pressure gas pipe and a liquid pipe When the outdoor heat exchanger is switched to be connected to the refrigerant suction port of the compressor through the accumulator by the flow path switching means in the stopped outdoor unit among the plurality of outdoor units. In addition, the connection part on the outdoor heat exchanger side in the refrigerant pipe connecting the outdoor heat exchanger and the accumulator is positioned higher than the connection part on the accumulator side so that the liquid refrigerant staying in the outdoor heat exchanger flows to the accumulator. It is intended.

  According to the air conditioner of the present invention configured as described above, the connection portion on the outdoor heat exchanger side in the refrigerant pipe connecting the outdoor heat exchanger and the accumulator is positioned above the connection portion on the accumulator side. Thereby, the liquid refrigerant staying in the outdoor heat exchanger provided in the outdoor unit in which the driven compressor does not exist flows into the accumulator of the outdoor unit by gravity, so that the driven compressor is The refrigerant is not sucked into the outdoor unit including the compressor driven from the non-existing outdoor unit, and the refrigerant does not concentrate on the outdoor unit. Therefore, it is possible to prevent an overflow from occurring in the accumulator provided in the outdoor unit including the compressor that is being driven.

It is a refrigerant circuit diagram of the air conditioning apparatus which is an Example of this invention, and is a refrigerant circuit diagram explaining the flow of the refrigerant | coolant in the case of performing a cooling operation. It is a figure explaining the positional relationship and refrigerant | coolant piping connection of the outdoor heat exchanger and accumulator in an outdoor unit in the air conditioning apparatus which is an Example of this invention. It is a refrigerant circuit diagram for demonstrating the effect of this invention in the air conditioning apparatus which is an Example of this invention.

  Embodiments of the present invention will be described below in detail with reference to the accompanying drawings. As an example, five indoor units are connected in parallel to three outdoor units by refrigerant piping, and air that can be operated by selecting a cooling operation and a heating operation for each indoor unit, that is, a so-called air conditioning-free operation can be performed. The harmony device will be described as an example. The present invention is not limited to the following embodiments, and can be variously modified without departing from the gist of the present invention.

  As shown in FIG. 1, the air conditioner 1 in this embodiment includes three outdoor units 2a to 2c, five indoor units 8a to 8e, five diversion units 6a to 6e, and a high-pressure gas pipe. 30, high pressure gas distribution pipes 30 a to 30 c, low pressure gas pipe 31, low pressure gas distribution pipes 31 a to 31 c, a liquid pipe 32, liquid distribution pipes 32 a to 32 c, and branching units 70, 71, 72. The outdoor units 2a to 2c, the indoor units 8a to 8e, and the diversion units 6a to 6e are connected to each other by the branching units 70, 71, 72, the high pressure gas pipe 30, the low pressure gas pipe 31, and the liquid pipe 32. The refrigerant circuit of the air conditioner 1 is configured.

  In the air conditioner 1, various operation operations can be performed according to the open / close states of various valves provided in the outdoor units 2a to 2c and the diversion units 6a to 6e. In FIG. 1, a case where the cooling operation is performed by all the indoor units 8a to 8e from among these operation operations will be described as an example.

FIG. 1 is a refrigerant circuit diagram when the cooling operation is performed. As shown in FIG. 1, the three outdoor units 2a to 2c include compressors 21a to 21c, four-way valves 22a to 22c as flow path switching means, outdoor heat exchangers 23a to 23c, and accumulators 24a to 24c. The outdoor fans 25a to 25c and the outdoor fans 26a to 26c, the outdoor expansion valves 27a to 27c for opening and closing the outdoor unit liquid pipes 35a to 35c connected to the outdoor heat exchangers 23a to 23c, and the closing valves 40a to 40c, There are provided closing valves 41a to 41c and closing valves 42a to 42c.
Since the configurations of the outdoor units 2a to 2c are all the same, in the following description, only the configuration of the outdoor unit 2a will be described, and detailed descriptions of the other outdoor units 2b and 2c will be omitted.

  The compressor 21a is a variable capacity compressor that can vary the operating capacity by being driven by a motor (not shown) whose rotation speed is controlled by an inverter. As shown in FIG. 1, a refrigerant discharge port (hereinafter referred to as a discharge side) of the compressor 21a is connected to a closing valve 40a by an outdoor unit high-pressure gas pipe 33a, and is connected to a connection point P from the outdoor unit high-pressure gas pipe 30a. The refrigerant piping branched off at is connected to the four-way valve 22a. Further, the refrigerant suction port (hereinafter referred to as the suction side) of the compressor 21a is connected to the outflow side of the accumulator 24a by a refrigerant pipe.

  The four-way valve 22a is a valve for switching the flow direction of the refrigerant, and includes four ports a to d. In the four-way valve 22a, a refrigerant pipe branched from the outdoor unit high-pressure gas pipe 33a at the connection point P is connected to the port a. The port b and the outdoor heat exchanger 23a are connected by a connection pipe 36a that is a refrigerant pipe, and the port c and the inflow side of the accumulator 24a are connected by a connection pipe 37a that is a refrigerant pipe. The port d is sealed.

  The outdoor heat exchanger 23a is composed of a large number of fins formed of an aluminum material and a plurality of copper tubes through which a refrigerant flows. One end of the outdoor heat exchanger 23a is connected to the port b of the four-way valve 22a via the connecting pipe 36a, and the other end of the outdoor heat exchanger 23a is connected to the closing valve 42a via the outdoor unit liquid pipe 35a. The outdoor expansion valve 27a is interposed in the outdoor unit liquid pipe 35a, which will be described in detail later.

  The accumulator 24a separates the flowing refrigerant into a gas refrigerant and a liquid refrigerant. As described above, the outflow side of the accumulator 24a is connected to the suction side of the compressor 21a by the refrigerant pipe, and the compressor 21a sucks the gas refrigerant separated by the accumulator 24a. The inflow side of the accumulator 24a is connected to the port c of the four-way valve 22a by a connecting pipe 37a. The outdoor unit low-pressure gas pipe 34a is connected to the connection pipe 37a at the connection point Q.

  The outdoor fans 25a and 26a are arranged in parallel vertically, for example, and are rotated by a fan motor (not shown) to take outside air into the outdoor unit 2a, and after exchanging heat between the outside air and the refrigerant in the outdoor heat exchanger 23a, Exhaust outside the outdoor unit 2a.

  The outdoor expansion valve 27a is interposed between the outdoor heat exchanger 23a and the closing valve 42a of the outdoor unit liquid pipe 35a. When the outdoor heat exchanger 23a functions as a condenser, the outdoor expansion valve 27a is fully opened, or the discharge pressure and intermediate pressure sensor of the compressor 21a detected by a high pressure sensor 50a described later. It adjusts according to the difference with the hydraulic pressure detected by 52a. In addition, when the outdoor heat exchanger 23a functions as an evaporator, the opening degree is the degree of superheat of the refrigerant in the outdoor heat exchanger 23a (low-pressure saturation calculated from the suction pressure of the compressor 21a detected by a low-pressure sensor 51a described later) The temperature is adjusted according to the difference between the temperature and the refrigerant outlet temperature detected by the heat exchanger temperature sensor 56a. The low-pressure saturation temperature corresponds to the refrigerant temperature in the outdoor heat exchanger 23a when the outdoor heat exchanger 23a functions as an evaporator.

  The bypass pipe 38a has one end connected to the accumulator 24a and the other end connected to the outdoor unit low-pressure gas pipe 34a at the connection point R. A capillary tube 28a, which is a decompression means, is interposed in the bypass pipe 38a.

  In addition to the configuration described above, the outdoor unit 2a is provided with various sensors. As shown in FIG. 1, the outdoor unit high-pressure gas pipe 33a includes a high-pressure sensor 50a for detecting the pressure of refrigerant discharged from the compressor 21a, and a discharge temperature sensor for detecting the temperature of refrigerant discharged from the compressor 21a. 53a. Between the connection point R in the outdoor unit low-pressure gas pipe 34a and the closing valve 41a, a low-pressure sensor 51a for detecting the pressure of the refrigerant sucked into the compressor 21a is provided, and the connection point Q in the connection pipe 37a and the accumulator 24a. Is provided with a suction temperature sensor 54a for detecting the temperature of the refrigerant sucked into the compressor 21a. Between the outdoor expansion valve 27a and the closing valve 42a in the outdoor unit liquid pipe 35a, an intermediate pressure sensor 52a for detecting the pressure of the refrigerant flowing through the outdoor unit liquid pipe 35a and the temperature of the refrigerant flowing through the outdoor unit liquid pipe 35a are set. A refrigerant temperature sensor 55a for detection is provided.

  The connection pipe 36a is provided with a heat exchange temperature sensor 56a that detects the temperature of the refrigerant flowing out of the outdoor heat exchanger 23a or flowing into the outdoor heat exchanger 23a. Further, an outdoor air temperature sensor 57a for detecting the temperature of the outside air flowing into the outdoor unit 2a, that is, the outside air temperature, is provided in the vicinity of a suction port (not shown) of the outdoor unit 2a.

  The outdoor units 2b and 2c have the same configuration as that of the outdoor unit 2a, and FIG. 1 shows a configuration in which the end of each configuration described above is changed from a to b or c. However, the symbols of the ports of the four-way valves 22b and 22c and the connection points of the refrigerant pipes are changed, and the port e of the four-way valve 22b of the outdoor unit 2b corresponds to the ports a to d of the four-way valve 22a of the outdoor unit 2a. ~ H, the ports j ~ n are set in the four-way valve 22c of the outdoor unit 2c. Corresponding to the connection points P, Q, and R, the outdoor unit 2b has connection points S, T, and U, and the outdoor unit 2c has connection points V, W, and X.

In the refrigerant circuit shown in FIG. 1 (the refrigerant circuit when the air-conditioning apparatus 1 is performing the cooling operation), the outdoor heat exchangers 23a to 23c provided in the outdoor units 2a to 2c function as condensers. The four-way valves 22a to 22c are switched. Specifically, the four-way valve 22a is switched so that the port a and the port b communicate with each other and the port c and the port d communicate with each other. Similarly, the four-way valve 22b is switched so that the port e and the port f and the port g and the port h communicate with each other, and the four-way valve 22c is switched so that the port j and the port k and the port m and the port n communicate with each other.
In FIG. 1, the ports that communicate with the four-way valves 22a to 22c are indicated by solid lines, and the ports that are not communicated are indicated by broken lines.

  FIG. 2 is a schematic diagram showing the connection state of the outdoor heat exchanger 23a, the four-way valve 22a, and the accumulator 24a in the outdoor unit 2a by the refrigerant pipes and the vertical positional relationship in each arrangement. As shown in FIG. 2, in the above configuration, the outdoor heat exchanger 23a is disposed at the top, followed by the four-way valve 22a and the accumulator 24a in this order downward. That is, the connection part 23aa between the outdoor heat exchanger 23a and the connection pipe 36a is positioned higher than the connection part 24aa between the accumulator 24a and the connection pipe 37a.

Therefore, when the port b and the port c of the four-way valve 22a communicate with each other, that is, when the valve body 22aa of the four-way valve 22a is at the position indicated by the broken line shown in FIG. 2, the liquid refrigerant is retained in the outdoor heat exchanger 23a. In this case, the staying liquid refrigerant flows from the connecting pipe 36a to the ports b and c of the four-way valve 22a by gravity, and is connected to the accumulator 24a from the outdoor heat exchanger 23a. It flows into the accumulator 24a through 37a.
Since the same applies to the outdoor units 2b and 2c, detailed description is omitted. Further, the bypass pipe 38a is connected to the upper part of the accumulator 24a by a connecting portion 24ab.

  The five indoor units 8a to 8e include indoor heat exchangers 81a to 81e, indoor expansion valves 82a to 82e, and indoor fans 83a to 83e. In addition, since all the configurations of the indoor units 8a to 8e are the same, only the configuration of the indoor unit 8a will be described in the following description, and a detailed description of the other indoor units 8b to 8e will be omitted.

  One end of the indoor heat exchanger 81a is connected to the liquid pipe 32 via the indoor expansion valve 82a, and the other end is connected to a branch unit 6a described later. The indoor heat exchanger 81a functions as an evaporator when the indoor unit 8a performs a cooling operation, and functions as a condenser when the indoor unit 8a performs a heating operation.

  The indoor expansion valve 82 a has one end connected to the indoor heat exchanger 81 a and the other end connected to the liquid pipe 32. When the indoor heat exchanger 81a functions as an evaporator, the indoor expansion valve 82a is adjusted according to the required cooling capacity, and when the indoor heat exchanger 81a functions as a condenser, The opening is adjusted according to the required heating capacity.

  The indoor fan 83a is rotated by a fan motor (not shown), thereby taking indoor air into the indoor unit 8a, exchanging heat with the refrigerant in the indoor heat exchanger 81a, and then sending it indoors.

  In addition to the configuration described above, the indoor unit 8a is provided with various sensors. A refrigerant temperature sensor 84a for detecting refrigerant temperature is detected in the refrigerant pipe on the indoor expansion valve 82a side of the indoor heat exchanger 81a, and a refrigerant temperature is detected in the refrigerant pipe on the diversion unit 6a side of the indoor heat exchanger 81a. Refrigerant temperature sensors 85a are provided. A room temperature sensor 86a for detecting the temperature of the indoor air flowing into the indoor unit 2, that is, the room temperature, is provided in the vicinity of the indoor air inlet (not shown) of the indoor unit 8a.

  The air conditioner 1 includes five branch units 6a to 6e corresponding to the five indoor units 8a to 8e. The diversion units 6a to 6e include first electromagnetic valves 61a to 61e, second electromagnetic valves 62a to 62e, first diversion pipes 63a to 63e, and second diversion pipes 64a to 64e. In addition, since all the structures of the flow dividing units 6a-6e are the same, in the following description, only the structure of the flow dividing unit 6a is demonstrated, and detailed description is abbreviate | omitted about the other flow dividing units 6b-6e.

  One end of the first branch pipe 63 a is connected to the high pressure gas pipe 30, and one end of the second branch pipe 64 a is connected to the low pressure gas pipe 31. Further, the other end of the first diversion pipe 63a and the other end of the second diversion pipe 64a are connected to each other, and the connection portion and the indoor heat exchanger 81a are connected by a refrigerant pipe. The first solenoid valve 61a is provided in the first branch pipe 63a, and the second solenoid valve 62a is provided in the second branch pipe 64a. The first solenoid valve 61a and the second solenoid valve 62a are opened and closed, respectively. As a result, the indoor heat exchanger 81a of the indoor unit 8a corresponding to the flow dividing unit 6a is connected to the discharge side (high pressure gas pipe 30 side) or the suction side (low pressure gas pipe 31 side) of the compressor 21. The flow path of the refrigerant in the circuit can be switched.

  The connection state of the outdoor units 2a to 2c, the indoor units 8a to 8e and the branch units 6a to 6e described above, and the high pressure gas pipe 30, the low pressure gas pipe 31, and the liquid pipe 32 will be described with reference to FIG. One end of the high-pressure gas branch pipes 30a to 30c is connected to the shut-off valves 40a to 40c of the outdoor units 2a to 2c, respectively, and the other end of the high-pressure gas branch pipes 30a to 30c is connected to the branch device 70, respectively. One end of the high-pressure gas pipe 30 is connected to the branching device 70, and the other end of the high-pressure gas pipe 30 is branched and connected to the first branch pipes 63a to 63e of the branch units 6a to 6e.

  One end of each of the low pressure gas distribution pipes 31a to 31c is connected to each of the closing valves 41a to 41c of the outdoor units 2a to 2c, and the other end of each of the low pressure gas distribution pipes 31a to 31c is connected to a branching device 71. One end of the low-pressure gas pipe 31 is connected to the branch 71, and the other end of the low-pressure gas pipe 31 is branched and connected to the second branch pipes 64a to 64e of the branch units 6a to 6e.

  One end of the liquid distribution pipes 32a to 32c is connected to the closing valves 42a to 42c of the outdoor units 2a to 2c, and the other end of the liquid distribution pipes 32a to 32c is connected to the branching device 72. One end of the liquid pipe 32 is connected to the branching device 72, and the other end of the liquid pipe 32 branches to be connected to the indoor expansion valves 82a to 82e of the indoor units 8a to 8e.

Moreover, the indoor heat exchangers 81a to 81e of the indoor units 8a to 8e and the diversion units 6a to 6e respectively corresponding to the indoor units 8a to 8e are connected by a refrigerant pipe.
With the connection described above, the refrigerant circuit of the air conditioner 1 is configured, and the refrigeration cycle is established by flowing the refrigerant through the refrigerant circuit.

  Next, the operation | movement operation | movement of the air conditioning apparatus 1 in a present Example is demonstrated using FIG. In addition, in FIG. 1, when each heat exchanger with which the outdoor units 2a-2c and the indoor units 8a-8e were equipped becomes a condenser, hatching is attached | subjected, and when it becomes an evaporator, it illustrates in white. The open / closed states of the first electromagnetic valves 61a to 61e and the second electromagnetic valves 62a to 62e in the flow dividing units 6a to 6e are illustrated in black when they are closed, and are illustrated in white when they are open. Moreover, the arrow has shown the flow of the refrigerant | coolant.

  As shown in FIG. 1, when all the indoor units 8a to 8e perform the cooling operation and the required operation capacity is high, and all the outdoor units 2a to 2c are operated, each of the outdoor units 2a to 2c is operated. Each four-way valve 22a-22c is switched so that the provided outdoor heat exchangers 23a-23c function as a condenser.

  In the indoor units 8a to 8e, the first electromagnetic valves 61a to 61e of the branch units 6a to 6e corresponding to the indoor units 8a to 8e are closed, the first branch pipes 63a to 63e are shut off, and the second solenoid valves 62a to 62e are opened. Thus, the second branch pipes 64a to 64e are brought into a communication state. Thereby, all the indoor heat exchangers 81a to 81e of the indoor units 8a to 8e are evaporators.

  In the outdoor unit 2a, the high-pressure refrigerant discharged from the compressor 21a flows into the outdoor heat exchanger 23a from the connection point P via the four-way valve 22a, and is condensed by exchanging heat with the outside air. The refrigerant condensed in the outdoor heat exchanger 23a flows into the outdoor unit liquid pipe 35a, and the opening degree according to the difference between the discharge pressure of the compressor 21a taken in from the high pressure sensor 50a and the liquid pressure taken in from the intermediate pressure sensor 52a. The refrigerant passes through the outdoor expansion valve 27a and is reduced in pressure to become an intermediate pressure refrigerant, flows from the closing valve 42a through the liquid distribution pipe 32a, and flows into the branching device 72a. Similarly, the intermediate-pressure refrigerant that has flowed out of the outdoor unit 2b and the outdoor unit 2c flows through the liquid distribution pipes 32b and 32c connected to the respective shut-off valves 42b and 42c, and flows into the branching units 72, respectively.

  The intermediate-pressure refrigerant that has flowed into the branching device 72 from each of the outdoor units 2a to 2c flows into the liquid pipe 32 and branches into the indoor units 8a to 8c. The intermediate-pressure refrigerant that has flowed into the indoor units 8a to 8c is reduced in pressure by the indoor expansion valves 82a to 82e, becomes low-pressure refrigerant, and flows into the indoor heat exchangers 81a to 81e. The low-pressure refrigerant that has flowed into the indoor heat exchangers 81a to 81e exchanges heat with room air and evaporates, thereby cooling the room where the indoor units 8a to 8e are installed. Here, the indoor expansion valves 82a to 82e are indoor heat exchangers 81a to 81a which are evaporators calculated from the refrigerant temperature detected by the refrigerant temperature sensors 84a to 84e and the refrigerant temperature detected by the refrigerant temperature sensors 85a to 85e. The opening degree is determined according to the degree of refrigerant superheating at the 81e outlet.

  Specifically, the refrigerant flow rate is small with respect to the size of the cooling capacity required by the indoor units 8a to 8e, and the superheat degree of the refrigerant at the outlets of the indoor heat exchangers 81a to 81e increases accordingly. Then, the opening degree of the indoor expansion valves 82a to 82e is increased to increase the flow rate of the refrigerant. In addition, in the case where the refrigerant flow rate is large with respect to the size of the cooling capacity required by the indoor units 8a to 8e, and accordingly the degree of superheat of the refrigerant at the outlets of the indoor heat exchangers 81a to 81e is small, The flow rate of the refrigerant is decreased by decreasing the opening degree of the expansion valves 82a to 82e.

  The low-pressure refrigerant that has flowed out of the indoor heat exchangers 81a to 81e flows into the diversion units 6a to 6e, and flows through the second diversion pipes 64a to 64e provided with the open second electromagnetic valves 62a to 62e to low pressure. It flows into the gas pipe 31. The low-pressure refrigerant that has flowed into the low-pressure gas pipe 31 flows into the branching device 71 after merging in the low-pressure gas pipe 31, and branches from the branching device 71 to the low-pressure gas branch pipes 31a to 31c.

  The low-pressure refrigerant that has flowed from the low-pressure gas distribution pipe 31a into the outdoor unit low-pressure gas pipe 34a through the closing valve 41a of the outdoor unit 2a is sucked into the compressor 21a via the accumulator 24a and compressed again. Similarly, the low-pressure refrigerant that has flowed from the low-pressure gas distribution pipes 31b and 31c into the outdoor unit low-pressure gas pipes 34b and 34c via the shut-off valves 41b and 41c of the outdoor units 2b and 2c passes through the accumulators 24b and 24c. It is sucked into 21c and compressed again.

  Next, in FIG. 1 to FIG. 3, in the air-conditioning apparatus 1 of the present embodiment, when there is an outdoor unit that does not have a compressor being driven, the outdoor heat exchanger of each outdoor unit serves as a condenser. When switching from a functioning state to a functioning state as an evaporator, an outdoor unit having a compressor driven by liquid refrigerant staying in an outdoor heat exchanger of an outdoor unit in which there is no driven compressor The action and effect of preventing the liquid refrigerant from concentrating on the accumulator of the outdoor unit and causing the overflow by being drawn into the accumulator will be described.

  In the following description, each of the outdoor units 2b and 2c is provided as the three indoor units 8c to 8e stop operating from the state where the air conditioner 1 performs the cooling operation shown in FIG. The compressors 21b and 21c are stopped, and then the indoor units 8a and 8b that are in operation are switched from the cooling operation to the heating operation, that is, the refrigerant circuit shown in FIG. 3 is taken as an example. I will give you a description.

  In FIG. 3, the configurations of the outdoor units 2a to 2c, the indoor units 8a to 8e, and the diversion units 6a to 6e are the same as those described in FIG. In the stopped indoor units 8c to 8e, the indoor expansion valves 82c to 82e are fully closed and the first electromagnetic valves 61c to 61e are closed. In the stopped outdoor units 2b and 2c, the outdoor expansion valves 27b and 27c are fully closed. The fully closed expansion valve and the closed solenoid valve are shown in black in FIG.

  When each of the operating indoor units 8a and 8b is switched from the cooling operation to the heating operation, the four-way valve 22a of the outdoor unit 2a driven by the compressor 21a is connected so that the port a and the port d communicate with each other. The ports b and c are switched so as to communicate with each other (in FIG. 3, the communicating ports are indicated by a solid line. The same applies hereinafter). As a result, the outdoor heat exchanger 23a functions as an evaporator, and the port b side of the outdoor heat exchanger 23a is connected to the accumulator 24a via the connection pipe 36a, the four-way valve 22a, and the connection pipe 37a.

  At this time, for the outdoor units 2b and 2c in which the compressors 21b and 21c are stopped, the four-way valves 22b and 22c are switched similarly to the outdoor unit 2a. The four-way valve 22b is switched so that the port e and the port h communicate with each other and the port f and the port g communicate with each other, and the port f side of the outdoor heat exchanger 23b is connected to the connection pipe 36b, the four-way valve 22b and the connection. It is connected to the accumulator 24b via the pipe 37b. The four-way valve 22c is switched so that the port j and the port n communicate with each other and the port k and the port m communicate with each other. The port k side of the outdoor heat exchanger 23c is connected to the connection pipe 36c and the four-way valve 22c. And it is connected to the accumulator 24c through the connecting pipe 37c.

  When the outdoor units 2b and 2c have the refrigerant circuit described above, they are condensed when the outdoor heat exchangers 23b and 23c function as condensers and do not evaporate when switched to function as evaporators. The liquid refrigerant (hereinafter referred to as liquid refrigerant staying in the outdoor heat exchangers 23b and 23c) is connected to the accumulators 24b and 24c via the connection pipes 36b and 36c, the four-way valves 22b and 22c, and the connection pipes 37b and 37c. Flow into. As described in FIG. 2, this is because the connection portions 23ba and 23ca between the outdoor heat exchangers 23b and 23c and the connection pipes 36b and 36c are replaced by the connection portions 24ba and 24ca between the accumulators 24b and 24c and the connection pipes 37b and 37c. By being arranged at a higher position, and because the shape of the connecting pipes 37b and 37c is inclined toward the accumulators 24b and 24c from the outdoor heat exchangers 23b and 23c, the outdoor heat exchange is performed. This is because the liquid refrigerant staying in the vessels 23b and 23c flows into the lower accumulators 24b and 24c by gravity.

  Specifically, in the outdoor unit 2b, the liquid refrigerant staying in the outdoor heat exchanger 23b flows from the connection pipe 36b through the four-way valve 22b through the connection pipe 37b and flows into the accumulator 24b. In the outdoor unit 2c, the liquid refrigerant staying in the outdoor heat exchanger 23c flows from the connection pipe 36c through the four-way valve 22c through the connection pipe 37c and flows into the accumulator 24c. In FIG. 3, the flow of the liquid refrigerant is indicated by solid arrows.

  As described above, the liquid refrigerant staying in the outdoor heat exchangers 23b and 23c of the outdoor units 2b and 2c in which the compressors 21b and 21c are stopped flows into the accumulators 24b and 24c of each outdoor unit. The amount of liquid refrigerant flowing into the outdoor unit 2a driven by the compressor 21a can be reduced via the low pressure gas distribution pipes 31b and 31c, the branching device 71 and the low pressure gas distribution pipe 31a connected to 2b and 2c, It is possible to prevent the liquid refrigerant from overflowing in the accumulator 24a of the outdoor unit 2a.

In this embodiment, each outdoor unit is provided with a bypass pipe (38a to 38c) that connects the accumulator and the low-pressure gas pipe. In the outdoor units 2b and 2c in which the compressors 21b and 21c are stopped, liquid refrigerant may flow into the accumulators 24b and 24c, so that overflow of the liquid refrigerant may occur in the accumulators 24b and 24c. The liquid refrigerant in 24c is caused to flow through bypass pipes 38b and 38c, and is depressurized by capillary tubes 28b and 28c to flow out as gas refrigerant to low-pressure gas branch pipes 31b and 31c, thereby causing liquid refrigerant overflow in accumulators 24b and 24c. Can be prevented.
In FIG. 3, the refrigerant flows from the accumulator 24b of the outdoor unit 2b and the accumulator 24c of the outdoor unit 2c are indicated by dashed arrows.

  Further, since the connecting portions 24bb and 24cb of the bypass pipes 38b and 38c are disposed above the accumulators 24b and 24c, and are disposed below the connecting sections 24ba and 24ca, the outdoor unit low pressure from the connecting pipes 37b and 37c. The liquid refrigerant flowing out to the gas pipes 34b and 34c is decompressed by the action of the capillary tubes 28b and 28c. Therefore, the inflow of the liquid refrigerant to the outdoor unit 2a that is driven by the compressor 21a can be reduced.

  As described above, in the air conditioner of the present invention, the connection portion on the outdoor heat exchanger side in the refrigerant pipe connecting the outdoor heat exchanger and the accumulator is positioned above the connection portion on the accumulator side. Thereby, the liquid refrigerant staying in the outdoor heat exchanger provided in the outdoor unit in which the driven compressor does not exist flows into the accumulator of the outdoor unit by gravity, so that the driven compressor is The refrigerant is not sucked into the outdoor unit including the compressor driven from the non-existing outdoor unit, and the refrigerant does not concentrate on the outdoor unit. Therefore, it is possible to prevent an overflow from occurring in the accumulator provided in the outdoor unit including the compressor that is being driven.

DESCRIPTION OF SYMBOLS 1 Air conditioning apparatus 2a-2c Outdoor unit 6a-6e Flow dividing unit 8a-8e Indoor unit 21a-21c Compressor 22a-22c Four-way valve 23a-23c Outdoor heat exchanger 23aa-23ca Connection part 24a-24c Accumulator 24aa-24ca Connection part 24ab-24cb connection portion 27a-27c outdoor expansion valve 28a-28c capillary tube 31 low pressure gas pipe 31a-31c low pressure gas distribution pipe 34a-34c outdoor unit low pressure gas pipe 36a-36c connection pipe 37a-37c connection pipe 38a-38c bypass pipe 61a -61e 1st solenoid valve 62a-62e 2nd solenoid valve 63a-63e 1st branch pipe 64a-64e 2nd branch pipe 81a-81e Indoor heat exchanger 82a-82e Indoor expansion valve

Claims (4)

A compressor, an outdoor heat exchanger, a flow path switching means connected to one end of the outdoor heat exchanger and switching the connection of the outdoor heat exchanger to a refrigerant discharge port or a refrigerant suction port of the compressor; and an accumulator An air conditioner comprising a plurality of outdoor units, and a plurality of indoor units connected to the plurality of outdoor units in parallel by a high pressure gas pipe, a low pressure gas pipe and a liquid pipe,
Among the plurality of outdoor units, the outdoor unit in which the driven compressor does not exist, and the outdoor heat exchanger is connected to the refrigerant suction port of the compressor via the accumulator by the flow path switching unit. A connection portion on the outdoor heat exchanger side in the refrigerant pipe connecting the outdoor heat exchanger and the accumulator so that the liquid refrigerant staying in the outdoor heat exchanger flows to the accumulator. The air conditioner is located higher than the connection part on the accumulator side.   The refrigerant pipe connecting the outdoor heat exchanger and the accumulator is shaped and arranged so as to incline from the connecting portion on the outdoor heat exchanger side toward the connecting portion on the accumulator side. The air conditioning apparatus according to claim 1.   3. The plurality of outdoor units are provided with bypass pipes for connecting the accumulator and the low-pressure gas pipes, and pressure reducing means is interposed in the bypass pipes. The air conditioning apparatus described in 1.   The air conditioner according to claim 3, wherein a connection portion of the bypass pipe on the accumulator side is provided on an upper portion of the accumulator.

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