KR101723689B1 - Air conditoner - Google Patents

Abstract

The present invention relates to an air conditioner. An air conditioner according to one aspect includes: an outdoor unit having an outdoor heat exchanger and at least one compressor; And a plurality of indoor units connected to the outdoor unit, wherein the outdoor heat exchanger includes a plurality of heat exchanging units for allowing the refrigerant to flow in parallel, and a plurality of four-way valves for changing the flow state of the plurality of heat exchanging units Wherein when the switching condition of the outdoor heat exchanger is satisfied while the plurality of heat exchanging sections are operated as any one of the condenser and the evaporator, a part of the plurality of heat exchanging sections And the heat exchanging portion is switched to the other flow path of the condenser and the evaporator.

Description

Air conditioner

The present invention relates to an air conditioner.

Background Art [0002] Generally, an air conditioner is a device for cooling and heating indoor air or purifying air using a refrigerant cycle including a compressor, a condenser, an expansion device, and an evaporator to create a more comfortable indoor environment for a user.

The air conditioner includes an air conditioner in which one indoor unit is connected to one outdoor unit, and a multi-type air conditioner in which a plurality of indoor units are connected to one or more outdoor units to provide a plurality of air conditioners.

An object of the present invention is to provide an air conditioner in which indoor cooling can be continuously performed even when the outdoor temperature is low.

It is another object of the present invention to provide an air conditioner in which defrosting can be performed while the heating performance is maintained.

An air conditioner according to one aspect includes: an outdoor unit having an outdoor heat exchanger and at least one compressor; And a plurality of indoor units connected to the outdoor unit, wherein the outdoor heat exchanger includes a plurality of heat exchanging units for allowing the refrigerant to flow in parallel, and a plurality of four-way valves for changing the flow state of the plurality of heat exchanging units Wherein when the switching condition of the outdoor heat exchanger is satisfied while the plurality of heat exchanging sections are operated as any one of the condenser and the evaporator, a part of the plurality of heat exchanging sections And the heat exchanging portion is switched to the other flow path of the condenser and the evaporator.

According to the proposed invention, when the cooling load of the indoor unit becomes equal to or lower than the reference load in a state where the outdoor temperature becomes equal to or lower than the reference temperature, a part of the plurality of heat exchanging units is switched to the evaporator state to eliminate the imbalance between the condensing capacity and the evaporating capacity And the evaporation temperature is prevented from being lowered, so that the cooling performance is maintained and continuous cooling can be performed.

Also, during the defrosting operation of the air conditioner, since the indoor unit performs the heating operation, continuous heating of the room can be performed, and indoor comfort can be maintained.

In addition, since the four-way valve switches the heat exchanging portion to the flow path switching, and the bypass pipe and the valve for flowing the high-temperature high-pressure refrigerant to the heat exchanging portion for defrosting are unnecessary, the cost is reduced. In addition, since a separate valve is not required, the flow rate of the refrigerant flowing to the defrosting heat exchanger is not reduced, and the defrost time can be shortened.

1 is a configuration diagram of an air conditioner according to an embodiment of the present invention;
2 is a view showing a flow of refrigerant in a cooling operation of an air conditioner according to the present invention.
3 is a control block diagram of an air conditioner according to the present invention.
4 is a flowchart for explaining a control method of the outdoor unit when the air conditioner is in the cooling operation.
5 is a view showing a flow of refrigerant in a state where the switching condition of the outdoor heat exchanger is satisfied;
6 is a flowchart for explaining a control method of an outdoor unit when the air conditioner is in a heating operation;
7 is a view showing a refrigerant flow when defrosting of an outdoor heat exchanger is performed;

Hereinafter, embodiments of the present invention will be described in detail.

1 is a configuration diagram of an air conditioner according to an embodiment of the present invention.

Referring to FIG. 1, an air conditioner according to an embodiment of the present invention includes an outdoor unit 10 and an indoor unit 2 connected to the outdoor unit 10 by a distributor 3.

The indoor unit (2) includes a plurality of indoor units (21, 22, 23, 24). In this specification, for convenience of explanation, it is shown that four indoor units are connected to a single outdoor unit, but in this specification, there is no limitation on the number of indoor units and the number of outdoor units. That is, one or more indoor units may be connected to two or more outdoor units.

The outdoor unit (10) includes a compression unit (110) for compressing the refrigerant. The compression unit 110 may include a plurality of compressors 111, 112, and 113. Some of the compressors 111, 112 and 113 are inverter compressors 111 whose capacity is variable and others may be constant speed compressors 112 and 113. The plurality of compressors 111, 112, and 113 may be arranged in parallel. Some or all of the plurality of compressors may be operated depending on the capacity of the indoor unit. In the present embodiment, a plurality of compressors are provided in the indoor unit. Alternatively, one compressor may be provided.

The discharge side piping of each of the compressors 111, 112, and 113 includes an individual piping 118 and a joint piping 119. That is, the individual piping 118 of each of the compressors 111, 112, and 113 is connected to the joint piping 119. Each of the individual pipes 118 may be provided with oil separators 114, 115, and 116 for separating oil from the refrigerant and a temperature sensor 126 for sensing the temperature of the compressed refrigerant.

The joint pipe 119 is connected to a plurality of four-way valves 121 and 122 for switching the refrigerant flow path. The plurality of four-way valves 121 and 122 include a first four-way valve 121 and a second four-way valve 122. The first four-way valve 121 and the second four-way valve 122 are arranged in parallel.

The four-way valves 121 and 122 are connected to the outdoor heat exchanger 130 by first connection pipes 123 and 124, respectively. The first connection pipe includes a first heat exchange unit connection pipe 123 and a second heat exchange unit connection pipe 124.

The outdoor heat exchanger (130) includes a plurality of heat exchangers (131, 132). The plurality of heat exchanging units 131 and 132 includes a first heat exchanging unit 131 and a second heat exchanging unit 132. [ The first heat exchanging unit 131 and the second heat exchanging unit 132 may be separate heat exchanging units or heat exchanging units that are separated based on the refrigerant flow in a single outdoor heat exchanger. The first four-way valve 121 is connected to the first heat exchange unit 131 by the first heat exchange unit connection pipe 123 and the second four-way valve 122 is connected to the second heat exchange unit connection pipe 124 to the second heat exchanging part 132. [

The first heat exchanging part 131 and the second heat exchanging part 132 are arranged in parallel. For example, the first heat exchanging unit 131 and the second heat exchanging unit 132 may be disposed horizontally or vertically. Accordingly, the refrigerant can flow independently to the first heat exchanging part 131 and the second heat exchanging part 132. [ The refrigerant may flow to each of the first heat exchanging unit 131 and the second heat exchanging unit 132, or may flow to any heat exchanging unit. The flow direction of the refrigerant in the first heat exchanging part 131 and the second heat exchanging part 132 may be the same or opposite. The first heat exchanging unit 131 and the second heat exchanging unit 132 may operate independently. That is, each of the heat exchangers may independently function as a condenser or an evaporator.

In this specification, the outdoor heat exchanger has been described as being divided into two heat exchangers, but it can be otherwise divided into three or more heat exchangers.

The refrigerant in the outdoor heat exchanger 130 may be heat-exchanged with outdoor air blown by an outdoor fan motor assembly 140 (including an outdoor fan and a fan motor). One or more outdoor fan motor assemblies may be provided. In FIG. 1, for example, two outdoor fan motor assemblies are shown.

The four-way valves 121 and 122 may be connected to the accumulator 135 by a second connection pipe 134. The four-way valves 121 and 122 may be connected to the closing pipes 121a and 122a.

The outdoor unit (10) further includes an outdoor expansion mechanism (150). The outdoor expansion mechanism (150) does not expand the refrigerant when the refrigerant that has passed through the outdoor heat exchanger (130) passes, and expands the refrigerant when the refrigerant that has not passed through the outdoor heat exchanger (130) passes. The outdoor expansion mechanism 150 includes a first outdoor expansion valve 151 corresponding to the first heat exchange unit 131 and a second outdoor expansion valve 152 corresponding to the second heat exchange unit 132 do. The first outdoor expansion valve (151) and the second outdoor expansion valve (152) are arranged in parallel. That is, the refrigerant expanded by the first outdoor expansion valve 151 flows to the first heat exchange unit 131, and the refrigerant expanded by the second outdoor expansion valve 152 flows into the second heat exchange unit 132 < / RTI >

Each of the outdoor expansion valves 151 and 152 may be an electronic expansion valve (EEV), for example.

Meanwhile, the outdoor unit 10 is connected to the distributor 3 by a low-pressure orifice 311. The outdoor unit (10) is connected to the distributor (3) by a high-pressure orifice (321). The outdoor unit (10) is connected to the distributor (3) by a liquid pipe (331). The low-pressure pipe 311 is connected to the second connection pipe 134 and the high-pressure pipe 321 is connected to a joint pipe 119 on the upstream side of the four-way valve 121, 122. The liquid pipe (331) is connected to the outdoor expansion mechanism (150).

The distributor 3 is connected to the plurality of indoor units 21, 22, 23, 24 and the outdoor unit 10 to control the refrigerant flow. The distributor 3 is connected to the indoor units 21, 22, 23 and 24 by means of an indoor engine 313 and an indoor liquid pipe 333 and is connected to the low pressure pipe 311, the high pressure pipe 321 and the liquid pipe 331, To the outdoor unit (10).

The distributor 3 includes a low pressure gas pipe 31, a high pressure gas pipe 32, a liquid pipe 33, a low pressure valve 314 and a high pressure valve 324. The low pressure pipe 311 and the indoor pipe 313 are connected to the low pressure gas pipe 31 and the liquid pipe 333 and the liquid pipe 331 are connected to the liquid pipe 33. The high pressure pipe 321 and the branch pipe 323 connected to the indoor liquid pipe 333 are connected to the high pressure gas pipe 32.

A first valve 315 is provided in the low pressure pipe 311 of the outdoor unit 10 and a second valve 325 is provided in the high pressure pipe 321. A third valve 335 . The low pressure valve 314 is provided in the indoor engine 313 and the high pressure valve 324 is connected to the branch pipe 323.

In the present invention, the low-pressure valve 314 and the high-pressure valve 324 may be an electronic expansion valve (EEV) whose opening degree is adjusted linearly or stepwise.

The indoor units 21, 22, 23 and 24 are connected to the indoor heat exchangers 211, 221, 231 and 241, the indoor fans 212, 222, 232 and 242, 233 and 243, respectively. The indoor expansion mechanisms 213, 223, 233, and 243 may be, for example, an electronic expansion valve (EEV).

Hereinafter, the refrigerant flow in the air conditioner of the present invention will be described.

First, when the air conditioner is operated in a heating mode, that is, when one or more indoor units are operated in a heating mode (in the example shown in FIG. 1, four indoor units are operated for heating), the compressor unit 110 of the outdoor unit 10 operates do. At this time, the low-pressure valve 314 is closed and the high-pressure valve 324 is opened. The first valve 315 provided in the low-pressure pipe 311 may be closed.

The high-temperature and high-pressure refrigerant discharged from the compression unit 110 flows to the high-pressure gas pipe 32 along the high-pressure pipe 321 by regulating the flow paths of the four-way valves 121 and 122. At this time, since the joint pipe 119 is connected to the closed pipes 121a and 122a by the four-way valves 121 and 122, the refrigerant can no longer flow at the ends of the closed pipes 121a and 122a, And flows along the high-pressure pipe 321.

The refrigerant flowing into the high pressure gas pipe 32 is sent to the respective indoor heat exchangers 211, 221, 231, and 241 through the respective branch pipes 323 and the indoor engine 313. Then, the refrigerant is condensed in the indoor heat exchangers (211, 221, 231, 241), and then passes through the indoor expansion mechanisms (213, 223, 233, 242) without expansion. Then, the refrigerant flows to the liquid pipe (33) through each indoor liquid pipe (333). The refrigerant flowing into the liquid pipe 33 flows along the liquid pipe 331 and flows to the outdoor heat exchanger 130 after being expanded by the outdoor expansion mechanism 150. Then, the refrigerant is evaporated while passing through the outdoor heat exchanger 130, and then flows into the accumulator 135 through the four-way valves 121 and 122. The gaseous refrigerant in the refrigerant flowing into the accumulator 135 flows into the compression unit 110.

2 is a view showing the flow of refrigerant during the cooling operation of the air conditioner according to the present invention.

Referring to Fig. 2, the cooling operation will be described.

On the other hand, when the air conditioner is in the cooling mode, that is, when one or more indoor units are in the cooling mode (for example, four indoor units are heated), the compression unit 110 operates. At this time, the high-pressure valve 324 is closed and the low-pressure valve 314 is opened. The second valve 325 provided in the high-pressure pipe 321 may be closed.

The high-temperature and high-pressure refrigerant discharged to the compression unit 110 flows to the outdoor heat exchanger 130 along the heat exchanger connecting pipes 123 and 124 by regulating the flow paths of the four-way valves 121 and 122. The refrigerant then passes through the outdoor heat exchanger (130) and is condensed and then passes through the outdoor expansion device (150) without expansion. The refrigerant that has passed through the outdoor expansion mechanism (150) flows to the liquid pipe (33) along the liquid pipe (331). The refrigerant flowing into the liquid pipe 33 is expanded while flowing through the indoor expansion valves 213, 223, 233, and 243 through the respective indoor liquid pipes 313. The expanded refrigerant is evaporated while passing through the respective indoor heat exchangers (211, 221, 231, 241). Then, the evaporated refrigerant flows to the low-pressure gas pipe 31 along the indoor engine 313. The refrigerant flowing into the low-pressure gas pipe 31 flows to the second connection pipe 134 along the low-pressure pipe 311. The refrigerant then flows into the accumulator 135. The gaseous refrigerant in the refrigerant flowing into the accumulator flows into the compression unit 110.

3 is a control block diagram of an air conditioner according to the present invention.

2, the air conditioner includes an outdoor temperature sensor 17 for sensing an outdoor temperature, a first pressure sensor 18 and a second pressure sensor 19 for sensing pressure, And a control unit (16) capable of controlling at least the outdoor unit (10) based on the information sensed by the sensors (17, 18, 19).

In detail, the sensors 17, 18, and 19 may be provided in the outdoor unit 10. The first pressure sensor 18 may sense the pressure at the outlet of the compression unit 110. The second pressure sensor 19 may sense the inlet-side pressure of the compression unit 110.

The control unit 16 may be an indoor unit control unit installed in each of the indoor units 21, 22, 23 and 24 and an outdoor unit control unit installed in the outdoor unit 10 and may be a control unit installed in the outdoor unit 10 .

FIG. 4 is a flowchart for explaining a control method of the outdoor unit when the air conditioner is in the cooling operation mode, and FIG. 5 is a view showing the refrigerant flow in a state where the switching condition of the outdoor heat exchanger is satisfied.

Referring to FIGS. 4 and 5, at least one indoor unit 21 is cooled by the cooling operation command (S1). In Fig. 1, one indoor unit (first indoor unit) 21 performs cooling operation, for example. When the first indoor unit 21 is cooled, the first indoor heat exchanger 21 functions as an evaporator, and the outdoor heat exchanger (a plurality of heat exchangers) functions as a condenser.

During the cooling operation of the first indoor unit 21, it is determined whether or not the outdoor temperature is lower than the reference temperature (S2). At this time, the reference temperature may be 15 [deg.] C, for example. It is noted herein that the reference temperature is not limited and can be varied. The reference temperature may be set differently depending on the number or capacity of the indoor units to be operated.

If it is determined in step S2 that the outdoor temperature is lower than the reference temperature, it is determined whether the switching condition of the outdoor heat exchanger 130 is satisfied (S3). Specifically, when the switching condition of the outdoor heat exchanger 130 is satisfied, when the high pressure (discharge side pressure) of the compression unit 110 becomes equal to or lower than the reference pressure or when the compression ratio of the compression unit 110 is equal to or lower than the reference compression ratio . The high pressure of the compression unit 110 can be sensed by the first pressure sensor 18 and the compression ratio can be controlled by the pressure value sensed by the first pressure sensor 18 and the second pressure sensor 19 Can be judged.

In the case where the switching condition of the outdoor heat exchanger 130 is satisfied, for example, when only one indoor unit operates (when the load of the operating indoor unit is smaller than the reference load) or when two or more indoor units operate, May be the case where the cooling load is smaller than the reference load. In this case, since the condensation capacity of the outdoor heat exchanger 130 (the outdoor heat exchanger during the cooling operation of the indoor unit serves as the condenser) is larger than the evaporation capacity of the indoor heat exchanger (serving as the evaporator) There is a problem that the evaporation capacity becomes unbalanced, so that the continuous cooling operation becomes difficult and the cooling performance deteriorates.

This is especially problematic when the outdoor temperature is below the reference temperature. That is, when the outdoor temperature is lowered during the cooling operation of the indoor unit, the condensation amount is increased, so that the outlet temperature of the condenser (outdoor heat exchanger) is lowered. When the outlet temperature of the condenser is lowered, the evaporation temperature (indoor heat exchanger) is lowered. If the evaporation temperature is lowered, the piping of the indoor heat exchanger may be iced and the cooling performance may be deteriorated.

Therefore, in the present invention, it is first determined whether the outdoor temperature is lower than or equal to the reference temperature, and then it is determined whether or not the switching condition of the outdoor heat exchanger 130 is satisfied. For example, a room in which the indoor unit performs cooling operation when the outdoor temperature is equal to or lower than the reference temperature may be a specific room (for example, a computer room) in which the temperature should be maintained at a set temperature or lower.

If it is determined in step S3 that the switching condition of the outdoor heat exchanger 130 is satisfied, a part (for example, the second heat exchanging part 132) of the plurality of heat exchanging parts 131 and 132 serving as the condenser It is switched to the oil state.

In this specification, it is assumed that the second heat exchanger 132 of the first heat exchanger 131 and the second heat exchanger 132 is switched.

When the switching condition of the outdoor heat exchanger (130) is satisfied, the flow path is switched by the second four-way valve (122). In detail, the second heat exchanger connecting pipe 124 connected to the second heat exchanging unit 132 communicates with the second connecting pipe 134. Then, the opening degree of the second outdoor expansion valve (152) becomes zero. That is, the second outdoor expansion valve 152 is completely closed. In this case, when the outdoor fan motor assembly includes a plurality of fans, the outdoor fan corresponding to the second heat exchanger may be stopped or the rotational speed (RPM) may be reduced.

Then, the high-temperature and high-pressure refrigerant discharged from the compression unit 110 is no longer allowed to flow into the second heat exchanging unit 132. That is, the second heat exchanging unit 132 is switched to the flow path of the evaporator, but does not actually function as an evaporator.

Therefore, since only the first heat exchanger 131 acts as a condenser, the amount of condensation is reduced, and the drop of the evaporation temperature is minimized.

Since the second heat exchanging part 132 and the second connecting pipe 134 are communicated with each other, the refrigerant in the second heat exchanging part 132 flows into the second connecting pipe 134, And flows into the compression unit 110 after flowing through the lighter 135. Therefore, it is prevented that the refrigerant stagnates in the second heat exchanging part 132, so that the amount of circulating refrigerant is prevented from being insufficient.

After the second heat exchanging part 132 is switched, the process returns to step S2. If the outdoor temperature exceeds the reference temperature or the outdoor temperature is lower than the reference temperature, if the cooling load of the indoor unit exceeds the reference load, the second heat exchanger 132 returns to its original state. That is, the second heat exchanger 132 is switched back to the condenser state and actually functions as the condenser.

According to the present invention, when the cooling load of the indoor unit becomes equal to or lower than the reference load in a state where the outdoor temperature becomes equal to or lower than the reference temperature, a part of the plurality of heat exchanging units is switched to the evaporator state to eliminate the imbalance between the condensing capacity and the evaporating capacity , The evaporation temperature is prevented from being lowered, the cooling performance is maintained, and continuous cooling can be performed.

On the other hand, in the case of this embodiment, when the outdoor temperature is lower than the minimum temperature, the indoor heat exchanger may be controlled to be turned on after the indoor heat exchanger is turned off for a certain period of time to prevent freezing of the pipe of the indoor heat exchanger. At this time, when a part of the plurality of heat exchanging units is switched to the channel state of the evaporator, the condensation amount is reduced, and the evaporation temperature of the indoor heat exchanger is higher than when all of the plurality of heat exchanging units act as a condenser. Therefore, according to the present invention, the criterion of the minimum temperature can be further lowered. As a result, it can be understood that the temperature range in which cooling operation can be performed is increased.

FIG. 6 is a flow chart for explaining a control method of the outdoor unit when the air conditioner is in the heating operation mode, and FIG. 7 is a view showing the refrigerant flow when defrosting of the outdoor heat exchanger is performed.

Referring to FIGS. 6 and 7, the air conditioner is operated in the heating mode by the heating operation command (S11) (at least one indoor unit is heated). In Fig. 7, a case in which a plurality of indoor units performs a heating operation will be described. The indoor heat exchangers 211, 221, 231 and 232 function as a condenser and the outdoor heat exchanger (a plurality of heat exchangers) functions as an evaporator do.

During the heating operation of the air conditioner, it is determined whether the defrosting operation condition is satisfied in the controller 16 (S12). In this specification, whether or not the defrosting operation condition is satisfied can be determined by comparing the outlet pipe temperature of the outdoor heat exchanger with the outdoor temperature, for example.

In this specification, the determination as to whether or not the defrosting operation condition is satisfied can be performed by various methods other than the described method, and there is no limitation on the method for determining whether the defrosting operation condition is satisfied.

As a result of the determination in step S12, if the defrosting operation condition is satisfied, the air conditioner operates in the defrost operation mode. In detail, the plurality of heat exchanging units 131 and 132 may be defrosted sequentially (S13). That is, any one heat exchanger performs defrosting and the other heat exchanger performs a heating operation (acts as an evaporator). When the defrosting operation of any one of the heat exchanging units is completed, the next heat exchanging unit performs defrosting. In this embodiment, the defrosting order of the plurality of heat exchanging units may be set in advance, or the defrosting may be sequentially performed from the heat exchanging unit having a lower temperature by comparing the outlet refrigerant temperatures of the respective heat exchanging units. At this time, although not shown, a plurality of temperature sensors for detecting the refrigerant temperature at the outlet of each of the heat exchanging units are provided in the outdoor unit.

For example, when the second heat exchange section is set as a priority or the outlet refrigerant temperature of the second heat exchange section is lower than the outlet refrigerant temperature of the first heat exchange section, the second heat exchange section performs the defrosting first.

When the defrosting operation condition is satisfied, the flow path is switched by the second four-way valve 122, and the second heat exchanging part 132 is switched to the flow path state of the condenser and functions as a condenser. That is, the refrigerant discharged from the compression unit 110 flows into the second heat exchanger 132 through the second four-way valve 122. After passing through the second outdoor expansion valve 152 without expansion, it merges with the refrigerant flowing along the liquid pipe 331 and is expanded by the first outdoor expansion valve 151.

On the other hand, when the defrosting of the second heat exchanging part 132 is completed, the second heat exchanging part 132 is switched to the evaporator by switching the flow of the second four-way valve 122. Then, the first heat exchanger 131 is switched to the condenser to perform defrosting.

When the defrosting of the first heat exchanging part 131 is completed (S14), the first heat exchanging part 131 is switched to the evaporator, and the process returns to step S2. That is, all of the outdoor heat exchangers serve as evaporators.

According to the present invention, even during the defrosting operation of the air conditioner, since the indoor unit performs the heating operation, continuous heating of the room can be performed and the pleasantness of the room can be maintained.

In addition, since the four-way valve switches the heat exchanging portion to the flow path switching, and the bypass pipe and the valve for flowing the high-temperature high-pressure refrigerant to the heat exchanging portion for defrosting are unnecessary, the cost is reduced. In addition, since a separate valve is not required, the flow rate of the refrigerant flowing to the defrosting heat exchanger is not reduced, and the defrost time can be shortened.

When the defrosting operation condition is satisfied in the present embodiment, the defrosting operation condition is also referred to as the switching condition because the passage state is switched in some of the heat exchanging portions.

2: indoor unit 10: outdoor unit
121: first four-way valve 122: second four-way valve
130: outdoor heat exchanger

Claims (10)

A first and a second four-way valves controlled to switch the flow paths of the refrigerant flowing into the first and second heat exchange units, and a second and a third four-way valves respectively connected to the first and second heat exchange units, An outdoor unit including first and second expansion valves for controlling a flow of a refrigerant and an outdoor fan provided at one side of the first and second heat exchange units to generate an air flow;
A plurality of indoor units connected to the outdoor unit; And
And a control unit for controlling the outdoor unit,
If at least one indoor unit of the plurality of indoor units is in the cooling operation mode and the outdoor temperature is lower than the predetermined temperature,
Wherein,
The second four-way valve is switched to shut off the flow of the refrigerant discharged from the compressor to the second heat exchanger,
The second expansion valve is closed to guide the refrigerant of the second heat exchange section to the outlet side of the compressor,
And controls the rotation speed of the outdoor fan to be reduced. The method according to claim 1,
Wherein the switching condition is satisfied when the compression ratio of the compressor is equal to or lower than the reference compression ratio or the discharge pressure is equal to or lower than the reference pressure.

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