WO2016098195A1

WO2016098195A1 - Air conditioning device

Info

Publication number: WO2016098195A1
Application number: PCT/JP2014/083403
Authority: WO
Inventors: 正有山
Original assignee: 三菱電機株式会社
Priority date: 2014-12-17
Filing date: 2014-12-17
Publication date: 2016-06-23
Also published as: JP6246394B2; EP3236168A1; EP3236168B1; EP3236168A4; JPWO2016098195A1

Abstract

An air conditioning device 1 comprises at least two outdoor units mounted with a compressor 101 and an outdoor heat exchanger 103, and at least one indoor unit 200 having an indoor throttling device and an indoor heat exchanger 201. While another outdoor unit 100 is in heating operations, at least one of the outdoor units 100 performs defrost operations in which refrigerant discharged from the compressor 101 bypasses to the outdoor heat exchanger 103 via hot gas bypass piping 118 by opening a first throttling device, a third throttling device is closed, and the degree that a second throttling device is opened is adjusted.

Description

Air conditioner

The present invention relates to an air conditioner that performs air conditioning or the like using a refrigeration cycle (heat pump cycle), and more particularly to an air conditioner that improves comfort when an indoor unit performs a heating operation.

In a conventional air conditioner, when heating operation is performed at a low outdoor temperature, frost may be attached to the fin surface and the refrigerant pipe of the outdoor heat exchanger that functions as an evaporator. If frost adheres to the fin surface and the refrigerant pipe of the outdoor heat exchanger, the air path pressure loss of the outdoor heat exchanger increases and the heat transfer performance deteriorates. Therefore, although it is necessary to perform defrosting operation | movement of an outdoor unit regularly, there existed a subject that heating operation had to be stopped at the time of defrosting operation.

In response to the above problem, an air conditioner that includes a plurality of outdoor units, performs heating operation during defrosting operation, and maintains comfort during defrosting operation is disclosed (for example, a patent) Reference 1 and Patent Document 2).
In an air conditioner (an air conditioner system having two outdoor units) including a plurality of outdoor units as described in Patent Document 1 and Patent Document 2, the load on the entire system when performing a defrosting operation The defrosting operation is performed when the temperature decreases indoors and does not cause discomfort even if the defrosting operation is performed while continuing the heating operation.

JP 2008-175410 A (see, for example, [0030] to [0047], FIG. 3 and FIG. 4) JP 2012-107790 A (see, for example, [0030] to [0050], FIG. 1 and FIG. 2)

In the air conditioner including a plurality of outdoor units as described in Patent Document 1 and Patent Document 2, when performing the defrosting operation while continuing the heating operation, that is, at least one outdoor unit is When other outdoor units perform the defrosting operation during the heating operation, the outdoor unit that performs the heating operation (hereinafter referred to as the heating operation side outdoor unit) and the outdoor unit that performs the defrosting operation (hereinafter referred to as the defrosting operation side outdoor unit) The refrigerant amount is biased toward the heating operation side outdoor unit.
Therefore, if the defrosting operation is continued or repeated for a long time, the refrigerant amount in the defrosting operation side outdoor unit is insufficient, causing an excessive increase in the compressor discharge temperature, etc., and the refrigerant operation amount in the heating operation side outdoor unit is increased. As a result, a large amount of liquid flows into the compressor (liquid back) and the like, causing a problem that stable operation is not possible.

The present invention has been made to solve the above-described problems. In an air conditioner including a plurality of outdoor units, when performing a defrosting operation while continuing a heating operation, between outdoor units ( An object of the present invention is to provide an air conditioner that can correct a deviation in refrigerant amount between a heating operation-side outdoor unit and a defrosting operation-side outdoor unit and perform stable operation.

An air conditioner according to the present invention includes at least two outdoor units on which a compressor and an outdoor heat exchanger are mounted, and at least one indoor unit on which an indoor expansion device and an indoor heat exchanger are mounted. The outdoor unit is connected in parallel to the indoor unit, and the compressor, the indoor heat exchanger, the indoor expansion device, and the outdoor heat exchanger are sequentially connected to form a refrigerant circuit in which the refrigerant circulates. In the air conditioner, the outdoor unit includes a hot gas bypass pipe that bypasses the refrigerant discharged from the compressor to the outdoor heat exchanger, and a first throttle that adjusts a flow rate of the refrigerant flowing through the hot gas bypass pipe A liquid bypass pipe that is bypassed from a connecting pipe connecting the apparatus, the indoor unit and the outdoor heat exchanger, and connected to a suction side of the compressor; and the liquid bypass pipe. Adjusting the flow rate of the refrigerant flowing in the outdoor connection pipe on the outdoor heat exchanger side from the branch point of the second bypass device for adjusting the flow rate of the refrigerant and the liquid bypass pipe among the connection pipes. And at least one of the outdoor units includes a refrigerant discharged from the compressor via the hot gas bypass pipe when the first throttle unit is opened when the other outdoor unit is in a heating operation. Is bypassed by the outdoor heat exchanger, the third expansion device is closed, and the defrosting operation is performed in which the opening degree of the second expansion device is adjusted.

According to the air conditioner of the present invention, at least one outdoor unit is configured such that when the other outdoor unit is in a heating operation, the first throttle device is opened and the refrigerant discharged from the compressor passes through the hot gas bypass pipe. By bypassing the outdoor heat exchanger, closing the third expansion device, and performing the defrosting operation in which the opening degree of the second expansion device is adjusted, the deviation of the refrigerant amount between the outdoor units can be corrected, Stable operation can be performed without causing excessive discharge temperature of the compressor, liquid back, and the like.

It is a refrigerant circuit figure which shows an example of the air conditioning apparatus which concerns on embodiment of this invention. It is a control flow figure at the time of the defrost operation of the air conditioning apparatus which concerns on embodiment of this invention.

Embodiment.
FIG. 1 is a refrigerant circuit diagram illustrating an example of an air-conditioning apparatus 1 according to an embodiment of the present invention.
Hereinafter, the refrigerant circuit configuration of the air conditioner 1 will be described with reference to FIG. The air conditioner 1 is installed in a building, a condominium, or the like, and can perform a cooling operation and a heating operation at the same time by using a refrigeration cycle (heat pump cycle) that circulates a refrigerant (air conditioning refrigerant). Moreover, a defrosting operation can be performed.
In addition, in the following drawings including FIG. 1, the relationship of the size of each component may be different from the actual one. Further, the present invention is not limited to the embodiments described below.

As shown in FIG. 1, the air conditioning apparatus 1 according to the present embodiment includes outdoor units (heat source side units) 100A and 100B, an indoor unit (load side unit) 200, and a control device 300. .
The

outdoor units

100A and 100B are connected to the indoor unit 200 in parallel through refrigerant pipes to form a main refrigerant circuit, and the refrigerant is circulated through the refrigerant circuit to heat or cool the target space. The air conditioner 1 is configured by connecting the two

outdoor units

100A and 100B to the single indoor unit 200, but is particularly limited if the number of the outdoor units 100 is two (two) or more. Is not to be done.

Further, in FIG. 1, “A” is added after the code of each device provided in the outdoor unit 100 </ b> A, and “B” is added after the code of each device provided in the outdoor unit 100 </ b> B. ing. In the following description, “A” and “B” after the reference may be omitted, but it goes without saying that both the outdoor unit 100A and the outdoor unit 100B are equipped with each device.

The refrigerant pipe includes a gas pipe 105 through which a gaseous refrigerant (gas refrigerant) flows, a liquid pipe 106 through which a liquid refrigerant (liquid refrigerant or gas-liquid two-phase refrigerant) flows, and the like. The refrigerant to be circulated in the refrigerant circuit is not particularly limited. For example, R410A, R404A, or HFO (hydro-fluoro-olefin) that are HFC-based refrigerants, or CO ₂ , ammonia, or the like, which is a natural refrigerant, is used.

The outdoor unit 100A includes a compressor 101A, a four-way valve 102A, an outdoor heat exchanger (heat source side heat exchanger) 103A, an accumulator 104A, a first valve 107A, a second valve 108A, a blower 109A, a first temperature sensor 110A, a second Temperature sensor 111A, third temperature sensor 112A, first pressure sensor 113A, second pressure sensor 114A, liquid bypass piping 115A, bypass throttle device 116A, refrigerant heat exchanger 117A, hot gas bypass piping 118A, outdoor connection piping 119A, These configurations are housed in the main body case 120A.

The indoor unit 200 includes an indoor heat exchanger (load-side heat exchanger) 201, a throttle means 202, and a blower 203. These configurations are housed in a housing 204.

The refrigerant circuit of the air conditioner 1 in the outdoor unit 100A and the indoor unit 200, the compressor 101A, the four-way valve 102A, the indoor heat exchanger 201, the throttle means 202, the refrigerant heat exchanger 117A, the outdoor heat exchanger 103A, and the accumulator 104A Sequentially connected by piping. In the outdoor unit 100A, the hot gas that bypasses the outdoor heat exchanger 103A so that the refrigerant discharged from the compressor 101A toward the four-way valve 102A flows to the outdoor heat exchanger 103A without passing through the four-way valve 102A. A bypass pipe 118A is provided. In addition, a liquid bypass pipe 115A that bypasses the low-temperature refrigerant flowing from the indoor unit 200 toward the outdoor heat exchanger 103A to the inlet of the accumulator 104A (the suction side of the compressor 101A) is provided.

Compressor 101A compresses the sucked refrigerant to bring it into a high temperature / high pressure state. The four-way valve 102A switches the flow of the refrigerant flowing through the refrigerant circuit between the cooling operation and the heating operation.

The outdoor heat exchanger 103A performs heat exchange between the surrounding air and the refrigerant flowing in the outdoor heat exchanger 103A. The outdoor heat exchanger 103A functions as, for example, an evaporator and evaporates the refrigerant. Alternatively, the outdoor heat exchanger 103A functions as a radiator (condenser) and condenses and liquefies the refrigerant.
In the present embodiment, an example in which the outdoor unit 100A includes one heat exchanger will be described, but a configuration including a plurality of heat exchangers may be used.

Blower 109A blows air to outdoor heat exchanger 103A. The accumulator 104A is disposed between the suction side of the compressor 101A and the four-way valve 102A and stores excess refrigerant. The accumulator 104A is, for example, a container that stores excess refrigerant.

The bypass throttle device 116A is disposed at a position where the flow path of the liquid bypass pipe 115A can be adjusted. The refrigerant heat exchanger 117A includes an outdoor connection pipe 119A on the outdoor heat exchanger 103A side from a branch point with the liquid bypass pipe 115A among connection pipes between the expansion means 202 and the outdoor heat exchanger 103A. , And the liquid bypass pipe 115A.

For example, in the cooling operation, the bypass expansion device 116A and the refrigerant heat exchanger 117A have a low temperature whose flow rate is adjusted by the liquid (high temperature and high pressure) refrigerant (liquid refrigerant) flowing out of the outdoor heat exchanger 103A and the bypass expansion device 116A. This is an apparatus for supercooling the refrigerant supplied to the indoor unit 200 by exchanging heat with the low-pressure refrigerant. The liquid flowing through the bypass throttle device 116A is returned to the accumulator 104A through the liquid bypass pipe 115A.

The first valve 107A and the second valve 108A are, for example, electromagnetic valves, and adjust the flow rate of the refrigerant flowing through the refrigerant circuit by adjusting the opening thereof. 107 A of 1st valves are arrange | positioned in the position which can adjust the flow path of 118 A of hot gas bypass piping. The second valve 108A is disposed at a position where the flow path of the outdoor connection pipe 119A can be adjusted.
The first valve 107A and the second valve 108A may be on-off valves. Further, a three-way valve is provided instead of the first valve 107A and the second valve 108A, and the flow path of the hot gas bypass pipe 118A and the flow path between the header 134 and the outdoor heat exchanger 103A are switched. It may be.

The first pressure sensor 113A is a sensor that detects the pressure of the refrigerant, and detects the pressure of the refrigerant flowing into the accumulator 104A (or the pressure of the refrigerant on the suction side of the compressor 101A).
The first temperature sensor 110A is, for example, a thermistor, and detects the temperature of the refrigerant flowing into the accumulator 104A (or the temperature of the refrigerant on the suction side of the compressor 101A).
The saturation temperature of the refrigerant flowing into the accumulator 104A is obtained from the pressure of the first pressure sensor 113A, and it is compared with the temperature of the first temperature sensor 110A to determine whether the state of the refrigerant flowing into the accumulator 104A is superheated gas. Judgment can be made.

The second pressure sensor 114A is a sensor that detects the pressure of the refrigerant, and detects the pressure of the refrigerant discharged from the compressor 101A.
The second temperature sensor 111A is a thermistor, for example, and detects the temperature of the refrigerant discharged from the compressor 101A.
The saturation temperature of the refrigerant discharged from the compressor 101A is obtained from the pressure of the second pressure sensor 114A, and the state of the refrigerant discharged from the compressor 101A is superheated gas by comparing with the temperature of the second temperature sensor 111A. It can be determined whether there is.

The third temperature sensor 112A is, for example, a thermistor and detects the temperature of the refrigerant flowing through the outdoor heat exchanger 103A. The third temperature sensor 112A has four-way communication with the outdoor heat exchanger 103A so as to detect the refrigerant temperature on the refrigerant outflow side during the cooling operation or the defrosting operation and detect the refrigerant temperature on the refrigerant inflow side during the heating operation. It is installed between the valve 102A. Therefore, based on the detection result of the third temperature sensor 112A, it can be determined whether the outdoor unit 100A is performing a defrosting operation or a heating operation.

The indoor heat exchanger 201 performs heat exchange between the surrounding air and the refrigerant flowing in the indoor heat exchanger 201. The indoor heat exchanger 201 functions as, for example, an evaporator, and evaporates the refrigerant. Alternatively, the indoor heat exchanger 201 functions as a radiator (condenser) and condenses and liquefies the refrigerant.

The throttle means 202 functions as a pressure reducing valve or an expansion valve, and depressurizes or expands the refrigerant. The throttle means 202 is, for example, an electronic expansion valve whose opening degree can be variably controlled, and fine flow rate control can be performed by adjusting the opening degree. The throttle means 202 may be an inexpensive refrigerant flow rate adjusting means such as a capillary tube.

The outdoor unit 100B includes a compressor 101B, a four-way valve 102B, an outdoor heat exchanger (heat source side heat exchanger) 103B, an accumulator 104B, a first valve 107B, a second valve 108B, a blower 109B, a first temperature sensor 110B, a second A temperature sensor 111B, a third temperature sensor 112B, a first pressure sensor 113B, a second pressure sensor 114B, a liquid bypass pipe 115B, a bypass throttle device 116B, a refrigerant heat exchanger 117B, and a hot gas bypass pipe 118B, and these configurations Is housed in the main body case 120B.

For example, the compressor 101B of the outdoor unit 100B corresponds to the compressor 101A of the outdoor unit 100A. The four-way valve 102B, the outdoor heat exchanger 103B, the accumulator 104B, the first valve 107B, the second valve 108B, the blower 109B, the first temperature sensor 110B, the second temperature sensor 111B, the third temperature sensor 112B, and the first pressure sensor 113B, the second pressure sensor 114B, the liquid bypass pipe 115B, the bypass throttle device 116B, the refrigerant heat exchanger 117B, the hot gas bypass pipe 118B, and the outdoor connection pipe 119B respectively correspond to the same number of the outdoor unit 100A. .

Since the outdoor unit 100B has the same configuration as the outdoor unit 100A, detailed description thereof is omitted. The refrigerant circuit of the air conditioner 1 in the outdoor unit 100B and the indoor unit 200 is also the same as the refrigerant circuit of the air conditioner 1 in the outdoor unit 100A and the indoor unit 200, and thus detailed description thereof is omitted. .

Note that the outdoor unit 100A and the outdoor unit 100B may be arranged in the same housing.
Further, in order to switch the flow of the refrigerant flowing in the refrigerant circuit, a two-way valve or a three-way valve may be used in combination instead of the four-way valve 102.
Moreover, although the air conditioning apparatus 1 which concerns on this Embodiment shall be able to perform air_conditionaing | cooling operation and heating operation, it is good also as a structure which does not perform air_conditionaing | cooling operation, In that case, the four-way valve 102 is unnecessary. .

The

outdoor units

100A and 100B and the indoor unit 200 are connected by a gas pipe 105 and a liquid pipe 106 via

headers

132 and 134, respectively. During the heating operation, the refrigerant flowing out of the

outdoor units

100A and 100B merges at the header 132, and the refrigerant flowing out of the indoor unit 200 branches at the header 134. Further, during the cooling operation, the refrigerant flowing out of the

outdoor units

100A and 100B merges at the header 134, and the refrigerant flowing out of the indoor unit 200 branches at the header 132.

The control device 300 includes, for example, a microcomputer, and controls the outdoor unit 100 and the indoor unit 200 of the air conditioner 1 according to various operations. In the present embodiment, control device 300 controls bypass throttling device 116 in accordance with the values of first pressure sensor 113A, first temperature sensor 110A, second pressure sensor 114A, and second temperature sensor 111A. Do.

The bypass throttle device 116 corresponds to the “second throttle device” of the present invention, the first valve 107 corresponds to the “first throttle device” of the present invention, and the second valve 108 corresponds to the “third throttle device” of the present invention. The aperture means 202 corresponds to the “indoor aperture device” of the present invention.

Next, the operation | movement at the time of the heating operation of the air conditioning apparatus 1 is demonstrated.
In the following description, high pressure or low pressure represents a relative relationship of pressure in the refrigerant circuit. The same applies to the temperature, and the high temperature or the low temperature represents a relative relationship of the temperature in the refrigerant circuit. In addition, the main body of the operation of the air conditioner 1 below is the control device 300.

When heating operation is performed in the

outdoor units

100A and 100B, the

first valves

107A and 107B are closed and the

second valves

108A and 108B are opened.

The high-temperature and high-pressure gas (gas) refrigerant pressurized by the

compressors

101A and 101B of the

outdoor units

100A and 100B flows into the header 132 through the four-

way valves

102A and 102B. The gas refrigerant pressurized by the compressor 101A and the gas refrigerant pressurized by the compressor 101B merge at the header 132 and flow into the indoor unit 200.

The gas refrigerant that has flowed into the indoor unit 200 passes through the indoor heat exchanger 201 and is condensed by exchanging heat with ambient air. Then, the pressure of the refrigerant flowing out from the indoor heat exchanger 201 is adjusted by the throttle means 202, and the refrigerant in the intermediate pressure liquid or gas-liquid two-phase state is branched by the header 134 to be added to the outdoor unit 100A, Flows into 100B.

The refrigerant that has flowed into the

outdoor units

100A and 100B passes through the

outdoor heat exchangers

103A and 103B to exchange heat with the surrounding air, and is evaporated to become a gas refrigerant. This gas refrigerant is sucked into the

compressors

101A and 101B via the four-

way valves

102A and 102B and the

accumulators

104A and 104B. The refrigerant sucked into the

compressors

101A and 101B is pressurized again and discharged.

Next, the operation | movement at the time of the defrost driving | operation of the air conditioning apparatus 1 which concerns on this Embodiment is demonstrated.
In the following description, an example in which the defrosting operation is performed in the outdoor unit 100A will be described. At this time, heating operation is performed in the outdoor unit 100B. The defrosting operation may be performed by the outdoor unit 100B, and the heating operation may be performed by the outdoor unit 100A.
As described below, the air conditioner 1 continues the heating operation by performing the defrosting operation on one of the outdoor unit 100A or the outdoor unit 100B and performing the heating operation on the other of the outdoor unit 100A or the outdoor unit 100B. While performing the defrosting operation.

When performing the defrosting operation in the outdoor unit 100A, the first valve 107A is opened and the second valve 108A is closed. Thereby, a part of the high-temperature refrigerant discharged from the compressor 101A passes through the first valve 107A and flows into the outdoor heat exchanger 103A. The high-temperature refrigerant discharged from the compressor 101A, except for flowing into the outdoor heat exchanger 103A, flows into the header 132, merges with the refrigerant flowing out of the outdoor unit 100B and the header 132, and flows into the indoor unit 200. To do.

When the high-temperature refrigerant flows into the outdoor heat exchanger 103A, heat exchange between the high-temperature gas refrigerant and the frost attached to the outdoor heat exchanger 103A is performed. Specifically, the frost adhering to the outdoor heat exchanger 103A absorbs the heat of the high-temperature gas refrigerant. As a result, the frost attached to the outdoor heat exchanger 103A melts and flows down. At this time, since the second valve 108A is closed, the low-temperature refrigerant from the liquid pipe 106 does not flow into the outdoor heat exchanger 103A.

When the defrosting operation is performed in the outdoor unit 100A, the heating operation is performed in the outdoor unit 100B. That is, the high-temperature and high-pressure gas refrigerant pressurized by the compressor 101 </ b> B flows into the indoor unit 200 through the gas pipe 105. The gas refrigerant that has flowed into the indoor unit 200 passes through the indoor heat exchanger 201 and enters an intermediate-pressure liquid or gas-liquid two-phase state. Then, the intermediate pressure liquid or the gas-liquid two-phase refrigerant passes through the liquid pipe 106, passes through the outdoor heat exchanger 103B of the outdoor unit 100B, and becomes a gas refrigerant. This gas refrigerant is again sucked into the compressor 101A, pressurized and discharged.

As described above, during the defrosting operation of the air-conditioning apparatus 1 according to the present embodiment, in the outdoor unit 100A, part of the high-temperature refrigerant discharged from the compressor 101A is part of the indoor heat exchanger 201 of the indoor unit 200. Flow into. However, since the low temperature refrigerant that has flowed out of the indoor unit 200 does not flow into the outdoor unit 100A because the second valve 108A is closed, the amount of refrigerant is biased toward the outdoor unit 100B into which the low temperature refrigerant flows.

Therefore, during the defrosting operation, the bypass expansion device 116A of the outdoor unit 100A is opened, and the low-temperature refrigerant from the liquid pipe 106 passes through the liquid bypass pipe 115A without passing through the outdoor heat exchanger 103A. The accumulator 104A) is also returned to. Accordingly, the liquid refrigerant is returned to the outdoor unit 100A without lowering the defrosting performance of the air conditioner 1, thereby preventing the refrigerant amount from being biased between the outdoor units 100 (between the outdoor unit 100A and the outdoor unit 100B). it can.

The liquid bypass pipe 115A and the bypass expansion device 116A can be used to supercool the refrigerant supplied to the indoor unit 200 during the cooling operation by the refrigerant heat exchanger 117A.

FIG. 2 is a control flow diagram during the defrosting operation of the air-conditioning apparatus 1 according to the embodiment of the present invention.
FIG. 2 is a diagram showing a control flow related to the opening degree control of the bypass expansion device 116A for preventing the deviation of the refrigerant amount between the outdoor units 100 during the defrosting operation. The deviation of the refrigerant amount between the outdoor units 100 is determined by the degree of superheat (SH-A) of the refrigerant at the inlet of the accumulator 104A (or the suction side of the compressor 101A) of the outdoor unit 100A performing the defrosting operation.
The degree of superheat (SH-A) of the refrigerant at the inlet of the accumulator 104A is calculated by the difference between the saturation temperature obtained from the value of the first pressure sensor 113A and the value of the first temperature sensor 110A (STEP 11).

When SH-A obtained as described above is 3 ° C. (a predetermined first threshold value) or more, it is determined that the liquid refrigerant has not returned to the outdoor unit 100A, and the bypass throttling device 116A is set to a predetermined value X. Open (+ X the opening degree of the bypass throttle device 116A). On the other hand, when SH-A is less than 3 ° C., the opening degree of the bypass expansion device 116A is not changed (STEP 12).

Whether or not excessive refrigerant has returned to the outdoor unit 100A is determined by the degree of superheat (TdSH-A) of the refrigerant on the discharge side of the compressor 101A of the outdoor unit 100A that performs the defrosting operation. The superheat degree (TdSH-A) of the refrigerant on the discharge side of the compressor 101A is calculated from the difference between the saturation temperature obtained from the value of the second pressure sensor 114A and the value of the second temperature sensor 111A (STEP 13).

When TdSH-A obtained by the above is less than 20 ° C. (predetermined second threshold value), it is determined that excessive liquid refrigerant has returned to the outdoor unit 100A, and the bypass throttling device 116A has a predetermined value. Close by X (the opening of bypass bypass device 116A is -X). On the other hand, when TdSH-A is 20 ° C. or higher, the opening degree of the bypass expansion device 116A is not changed (STEP 14).

By performing the above STEP 11 to STEP 14 at regular intervals, the liquid refrigerant flowing into the outdoor unit 100A performing the defrosting operation can be controlled, and the deviation of the refrigerant amount between the outdoor units 100 can be corrected.

Note that the refrigerant control shown in FIG. 2 is similarly applied when the outdoor unit 100 performing the defrosting operation is switched or when there are three or more outdoor units 100.

As described above, according to the air conditioner 1 according to the present embodiment, at least one outdoor unit 100 is configured such that the first valve 107 is opened and the hot gas bypass pipe 118 is connected when the other outdoor unit 100 is in the heating operation. The refrigerant discharged from the compressor 101 is bypassed to the outdoor heat exchanger 103, the second valve 108 is closed, and the defrosting operation in which the opening degree of the bypass expansion device 116 is adjusted is performed between the outdoor units 100. The refrigerant amount deviation can be corrected, and stable operation can be performed without causing excessive discharge temperature, liquid back, or the like of the compressor 101.

Regarding the adjustment of the opening degree of the bypass expansion device 116, in detail, the bypass expansion device according to the superheat degree (SH-A) of the refrigerant at the inlet of the accumulator 104 and the superheat degree (TdSH-A) of the refrigerant on the discharge side of the compressor 101A. 116 is adjusted. The low-temperature refrigerant from the liquid pipe 106 also passes through the liquid bypass pipe 115 and returns to the outdoor unit 100 (accumulator 104) that performs the defrosting operation without passing through the outdoor heat exchanger 103. . By doing so, in the case of performing the defrosting operation while continuing the heating operation, it is possible to correct the deviation of the refrigerant amount between the outdoor units 100 and cause the discharge temperature of the compressor 101 to rise, the liquid back, etc. And stable operation can be performed.

The first threshold value and the second threshold value are not limited to the above values, and are determined according to the type of refrigerant. In addition, a value that opens the bypass diaphragm 116A when it is equal to or greater than the first threshold and a value that closes the bypass diaphragm 116A when it is less than the second threshold may be different.

1 Air conditioner, 100A outdoor unit, 100B outdoor unit, 101A compressor, 101B compressor, 102A four-way valve, 102B four-way valve, 103A outdoor heat exchanger, 103B outdoor heat exchanger, 104A accumulator, 104B accumulator, 105 gas piping , 106 liquid piping, 107A first valve, 107B first valve, 108A second valve, 108B second valve, 109A blower, 109B blower, 110A first temperature sensor, 110B first temperature sensor, 111A second temperature sensor, 111B 2nd temperature sensor, 112A 3rd temperature sensor, 112B 3rd temperature sensor, 113A 1st pressure sensor, 113B 1st pressure sensor, 114A 2nd pressure sensor, 114B 2nd pressure sensor, 115A liquid bypass piping, 11 B Liquid bypass piping, 116A bypass throttle device, 116B bypass throttle device, 117A refrigerant heat exchanger, 117B refrigerant heat exchanger, 118A hot gas bypass piping, 118B hot gas bypass piping, 119A outdoor connection piping, 119B outdoor connection piping , 120A body case, 120B body case, 132 header, 134 header, 200 indoor unit, 201 indoor heat exchanger, 202 throttle means, 203 blower, 204 housing, 300 control device.

Claims

At least two outdoor units equipped with a compressor and an outdoor heat exchanger;
And at least one indoor unit equipped with an indoor expansion device and an indoor heat exchanger,
The outdoor unit is connected in parallel to the indoor unit,
The compressor, the indoor heat exchanger, the indoor expansion device, and the outdoor heat exchanger are sequentially connected by piping, and constitute an air conditioner that constitutes a refrigerant circuit in which refrigerant circulates,
The outdoor unit is
Hot gas bypass piping for bypassing refrigerant discharged from the compressor to the outdoor heat exchanger;
A first expansion device that adjusts the flow rate of the refrigerant flowing through the hot gas bypass pipe;
A liquid bypass pipe bypassed from a connection pipe connecting the indoor unit and the outdoor heat exchanger, and connected to a suction side of the compressor;
A second expansion device that adjusts the flow rate of the refrigerant flowing through the liquid bypass pipe;
A third expansion device that adjusts the flow rate of the refrigerant that flows through the outdoor connection pipe that is on the outdoor heat exchanger side of a branch point with the liquid bypass pipe among the connection pipes,
At least one of the outdoor units is
When the other outdoor unit is in a heating operation, the first expansion device is opened, and the refrigerant discharged from the compressor is bypassed to the outdoor heat exchanger via the hot gas bypass pipe, and the third expansion device is An air conditioner that performs a defrosting operation that is closed and the opening of the second expansion device is adjusted.
The outdoor unit performing the defrosting operation is
The air conditioner according to claim 1, wherein the opening degree of the second expansion device is adjusted according to the degree of superheat of the refrigerant on the suction side of the compressor and the degree of superheat of the refrigerant on the discharge side of the compressor. .
The outdoor unit performing the defrosting operation is
If the degree of superheat of the refrigerant on the suction side of the compressor is equal to or greater than a predetermined first threshold, the opening of the second expansion device is opened by a predetermined value,
The opening degree of the second expansion device is closed by a predetermined value when the degree of superheat of the refrigerant on the discharge side of the compressor is less than a predetermined second threshold value. Air conditioner.
The outdoor unit is
A first pressure sensor for detecting the pressure of refrigerant on the suction side of the compressor;
A first temperature sensor for detecting the temperature of the refrigerant on the suction side of the compressor;
A second pressure sensor for detecting the pressure of the refrigerant on the discharge side of the compressor;
A second temperature sensor for detecting the temperature of the refrigerant on the discharge side of the compressor,
The outdoor unit performing the defrosting operation is
The degree of superheat of the refrigerant on the suction side of the compressor is calculated from the difference between the saturation temperature obtained from the value of the first pressure sensor and the value of the first temperature sensor,
The air conditioning according to claim 3, wherein the degree of superheat of the refrigerant on the discharge side of the compressor is calculated based on a difference between a saturation temperature obtained from a value of the second pressure sensor and a value of the second temperature sensor. apparatus.
The outdoor unit is
The air conditioner according to any one of claims 1 to 4, further comprising a refrigerant heat exchanger that performs heat exchange between the refrigerant flowing through the outdoor connection pipe and the refrigerant flowing through the liquid bypass pipe.