KR20140094864A - An air conditioner and a control method the same - Google Patents

Abstract

An air conditioner according to the present invention comprises: multiple outdoor units of which each has a compressor and a main expansion device; detection parts detecting the low pressure of a refrigerant sucked into the compressors; and a control part recognizing the existence of a first outdoor unit in which the low pressure detected by the detection parts is lower than or equal to predetermined pressure, wherein the control part controls at least one of the opening degree of the main expansion device of the first outdoor unit or the opening degree of the main expansion device of a second outdoor unit when the value of differential pressure between the low pressure in the second outdoor unit and the low pressure in the first outdoor unit is larger than or equal to a predetermined value. According to the present invention, a control method of the air conditioner having the outdoor units comprises: a step of operating the compressors in the outdoor units for a predetermined time; a step of detecting the suction pressure of the compressors, and recognizing the sizes of the suction pressure; a step of recognizing the existence of a second compressor with pressure equal to or larger than the suction pressure of the first compressor by at least the predetermined value when the suction pressure of the first compressor among the compressors is lower than or equal to the predetermined pressure; and a step of controlling at least one of the opening degree of the main expansion device of the outdoor unit with the second compressor or the opening degree of the main expansion device of the outdoor unit with the first compressor if the second compressor exists.

Description

[0001] The present invention relates to an air conditioner and a control method thereof,

The present invention relates to an air conditioner and a control method thereof.

The air conditioner is a device for keeping the air in a predetermined space in a most suitable condition according to the purpose of use and purpose. Generally, the air conditioner includes a compressor, a condenser, an expansion device, and an evaporator, and a refrigerant cycle for compressing, condensing, expanding, and evaporating the refrigerant is driven to cool or heat the predetermined space .

The predetermined space may be variously proposed depending on the place where the air conditioner is used. For example, when the air conditioner is installed in a home or an office, the predetermined space may be an indoor space of a house or a building. On the other hand, when the air conditioner is disposed in a car, the predetermined space may be a boarding space on which a person boarded.

When the air conditioner performs the cooling operation, the outdoor heat exchanger provided in the outdoor unit functions as a condenser, and the indoor heat exchanger provided in the indoor unit functions as an evaporator. On the other hand, when the air conditioner performs the heating operation, the indoor heat exchanger functions as a condenser and the outdoor heat exchanger functions as an evaporator.

1 is a view showing a configuration of an outdoor unit according to the related art.

1, an outdoor unit 1 according to the related art includes an upper panel 10 forming an upper outer surface of the outdoor unit 1, an upper panel 10 connected to the upper panel 10, And a side panel 30 connected to one side of the front panel 20 and one side of the top panel 10.

The front panel 20 may be provided with a suction grill 21 for allowing outside air to be sucked into the outdoor unit 1 and a suction frame 22 for fixing the position of the suction grill 21 . The top panel 10 may be provided with a discharge unit 11 through which the air sucked into the outdoor unit 100 through the suction grille 22 is discharged to the outside.

In the multi-type air conditioner, a plurality of indoor units (not shown) may be connected to the plurality of outdoor units 1. Between the outdoor unit 1 and the indoor unit (not shown), a common liquid pipe 40, which is a passage through which the liquid refrigerant moves, and a common engine 50, which is a passage through which the gas refrigerant moves, may be installed. A common pipe (60) for maintaining the balance of the refrigerant may be provided between the plurality of outdoor units (1).

In general, the common pipe 60 is installed so that the inlet sides of the outdoor heat exchangers (not shown) provided in the plurality of outdoor units 1 are communicated with each other so that the refrigerant is balanced between the outdoor units 1 do. Therefore, the refrigerant can be introduced into the outdoor heat exchanger (not shown) of the unused outdoor units of the plurality of outdoor units 1. The common pipe 60 may be a passage through which the high-pressure or low-pressure refrigerant is moved according to the operating state of the air conditioner.

However, since the common pipe 60 is installed at the inlet side of the outdoor heat exchanger (not shown) disposed in each of the plurality of outdoor units 1, there is a problem that installation work is troublesome. In addition, when the multi-type air conditioner is used, there is a problem of installation cost and additional work because the common pipe 60 must be additionally installed.

If the common pipe (60) is not provided, the amount of refrigerant moved along the common engine (50) installed in the plurality of outdoor units (1) during the heating operation of the air conditioner is unbalanced, There is a problem that the efficiency is lowered.

An object of the present invention is to provide an air conditioner capable of uniformly controlling the amount of refrigerant flowing from the outdoor unit to the indoor unit without providing a common pipe through which a high pressure or low pressure refrigerant moves between a plurality of outdoor units during a heating operation of the air conditioner. And a control method thereof.

An air conditioner according to the present invention includes: a plurality of outdoor units each having a compressor and a main expansion device; A sensing unit for sensing a low pressure of the refrigerant sucked into the compressor; And a controller for recognizing whether or not a first outdoor unit having a low pressure of the refrigerant sensed by the sensing unit is lower than a predetermined pressure, wherein the control unit controls the differential pressure between the low pressure of the second outdoor unit and the low pressure of the first outdoor unit And adjusts at least one of an opening of the main expansion device of the first outdoor unit or an opening of the main expansion unit of the second outdoor unit.

A method of controlling an air conditioner according to the present invention is a method of controlling an air conditioner including a plurality of outdoor units, the method comprising: driving compressors provided in the plurality of outdoor units for a set time; The suction pressure of the compressors is sensed and the magnitude is recognized; If a suction pressure of the first compressor among the compressors is equal to or lower than a set pressure, recognizing whether a second compressor having a pressure higher than a suction pressure of the first compressor exists; And adjusting at least one of an opening of the main expansion device of the outdoor unit having the second compressor or an opening of the main expansion unit of the outdoor unit having the first compressor if the second compressor is present .

According to the present invention, it is possible to control the amount of refrigerant discharged from the outdoor unit by controlling the opening degree of the main expansion device installed in each of the plurality of outdoor units during the heating operation of the air conditioner.

Therefore, it is not necessary to provide a common pipe for connecting the outdoor units, so that the piping installation work is simplified and the working efficiency is increased.

In addition, since the installation work of the common pipe is omitted, there is an effect that the cost of piping and piping installation can be saved.

1 is a view showing a configuration of an outdoor unit according to the related art.
2 is a system diagram showing an internal configuration of an outdoor unit according to the present invention;
3 is a view showing an outdoor unit and an indoor unit connected to each other according to the present invention.
4 is a block diagram of an air conditioner according to the present invention.
5 is a flow chart showing a control method of an air conditioner according to the present invention.
6 is a flowchart specifically illustrating the step S600 of FIG.

Hereinafter, some embodiments of the present invention will be described in detail with reference to exemplary drawings. It should be noted that, in adding reference numerals to the constituent elements of the drawings, the same constituent elements are denoted by the same reference symbols as possible even if they are shown in different drawings. In the following description of the embodiments of the present invention, a detailed description of known functions and configurations incorporated herein will be omitted when it may make the difference that the embodiments of the present invention are not conclusive.

2 is a system diagram showing an internal configuration of an outdoor unit according to the present invention.

Referring to FIG. 2, the air conditioner according to the present invention may include an outdoor unit 100 disposed outdoors and an indoor unit (refer to 500 in FIG. 3) connected to the outdoor unit 100 and disposed indoors.

The outdoor unit 100 includes a plurality of compressors 150 and 160 and a plurality of compressors 150 and 160 disposed at the outlet sides of the plurality of compressors 150 and 160 and separating the oil from the refrigerant discharged from the compressors 150 and 160 Oil separators 120 and 122 are included.

The plurality of compressors 150 and 160 include a constant speed compressor 150 and an inverter compressor 160 that are connected in parallel. The oil separators 120 and 122 are provided with a first oil separator 120 disposed at an outlet side of the constant speed compressor 150 and a second oil separator 122 disposed at an outlet side of the inverter compressor 160 ).

The outdoor unit 100 includes a recovery flow path 116 for recovering oil from the oil separators 120 and 122 to the compressors 150 and 160. That is, the recovery flow path 116 extends from the first oil separator 120 to the constant-speed compressor 150 and from the second oil separator 122 to the inverter compressor 160.

A high pressure sensor 125 for sensing the discharge high pressure of the refrigerant discharged from the compressors 150 and 160 and a refrigerant passing through the high pressure sensor 125 are connected to the outdoor heat exchanger 200 or a flow switching unit 130 for guiding the air to the indoor unit side.

When the air conditioner operates in the cooling mode, the refrigerant flows from the flow switching unit 130 to the outdoor heat exchanger 200. On the other hand, when the air conditioner performs the heating operation, the refrigerant flows from the flow switching unit 130 to the indoor heat exchanger side of the indoor unit.

The refrigerant that has passed through the outdoor heat exchanger 200 may be introduced into the supercooling heat exchanger 240. The supercooling heat exchanger 240 can be understood as an intermediate heat exchanger in which the first refrigerant circulating in the system and the refrigerant (the second refrigerant) in the refrigerant are branched and then heat-exchanged.

The outdoor unit (10) includes a supercooling flow path (242) through which the second refrigerant is branched. The supercooling passage 242 is provided with a supercooling expansion device 243 for reducing the pressure of the second refrigerant. The supercooling expansion device 243 may include an EEV (Electric Expansion Valve).

The second refrigerant heat-exchanged in the supercooling heat exchanger 240 may be introduced into the gas-liquid separator 250 or the compressors 150 and 160. The gas-liquid separator 250 separates the gaseous refrigerant before the refrigerant flows into the compressors 150 and 160. The separated gaseous refrigerant can be introduced into the compressors 150 and 160.

The supercooling passage 242 is branched into a first guide passage 244 for guiding the refrigerant to the gas-liquid separator 250 and a second guide passage 246 for guiding the refrigerant to the gas-liquid separator 250 and the compressors 150 and 160.

The first guide passage 244 is provided with a supercooling bypass valve 245 for selectively blocking the flow of the refrigerant. The amount of the refrigerant flowing into the gas-liquid separator 250 can be adjusted according to on / off or opening of the supercooling bypass valve 245.

The second guide passage 246 is provided with an injection valve 248 capable of controlling the amount of refrigerant injected into the compressors 150 and 160. The injection valve 248 may include EEV. The amount of the refrigerant injected into the compressors 150 and 160 can be adjusted according to on / off or opening of the injection valve 248.

The outdoor unit 100 is provided with a receiver 252 for storing at least a part of the first refrigerant passing through the supercooling heat exchanger 240 and a receiver 252 branched from the outlet of the supercooling heat exchanger 240 by the receiver 252 And a receiver inlet flow path 255 for guiding the flow of the refrigerant.

The receiver 252 may be coupled to the gas-liquid separator 250. That is, the receiver 252 and the gas-liquid separator 250 may be partitioned inside the refrigerant storage tank. For example, the gas-liquid separator 250 may be provided at an upper portion of the refrigerant storage tank, and the receiver 252 may be provided at a lower portion thereof.

The receiver inlet channel 255 is provided with a receiver inlet valve 253 for controlling the flow of the refrigerant. When the receiver inlet valve 253 is opened, at least a part of the refrigerant in the first refrigerant may flow into the receiver 252. The receiver inlet channel 255 is provided with a decompression device to reduce the pressure of the refrigerant flowing into the receiver 252.

To the receiver 252, a receiver outlet pipe 256 is connected. The receiver outlet pipe 256 may extend to the gas-liquid separator 250. At least a portion of the refrigerant stored in the receiver 252 may be introduced into the gas-liquid separator 250 through the receiver outlet pipe 256.

The receiver outlet pipe (256) is provided with a receiver outlet valve (254) capable of regulating the amount of refrigerant discharged from the receiver (252). The amount of refrigerant flowing into the gas-liquid separator 250 can be adjusted according to on / off or opening of the receiver outlet valve 254.

Hereinafter, the configuration of the outdoor heat exchanger 200 will be described.

The outdoor heat exchanger (200) includes a plurality of heat exchangers (210, 212) and an outdoor fan (218). The plurality of heat exchanging units 210 and 212 include a first heat exchanging unit 210 and a second heat exchanging unit 212 connected in parallel.

The outdoor heat exchanger 200 includes a variable flow channel 220 for guiding the flow of the refrigerant from one side of the first heat exchange unit 210 to the other side of the second heat exchange unit 212.

The outdoor heat exchanger 200 is provided with a shut-off valve 222 which is provided in the variable flow passage 220 to selectively block the flow of the refrigerant. The refrigerant that has passed through the first heat exchanging unit 210 or the second heat exchanging unit 212 may flow through the second heat exchanging unit 212 or the first heat exchanging unit 212 depending on whether the shut- (210). ≪ / RTI >

The first moving pipe (230) and the second moving pipe (231) are respectively provided with a first expansion device (s) and a second expansion device (233) for controlling the flow of refrigerant. The expansion devices 232 and 233 may include a plurality of expansion devices 234, and the plurality of expansion devices 234 may be connected in parallel.

When the first expansion device 232 is opened or its opening degree is increased, the amount of refrigerant flowing through the first movement pipe 230 is increased. When the second expansion device 233 is opened or its opening degree is increased, the amount of refrigerant flowing through the second movement pipe 231 is increased.

Hereinafter, a configuration in which the plurality of outdoor units 100 and a plurality of indoor units (see 500 in FIG. 3) are connected to each other will be described when the plurality of outdoor units 100 are constructed.

3 is a view showing an outdoor unit and an indoor unit connected to each other according to the present invention. Hereinafter, an example will be described in which two outdoor units and three indoor units are installed and connected. However, the number of outdoor units and indoor units is not limited thereto.

Referring to FIG. 3, each of the plurality of outdoor units 100 may include a first outdoor unit 110 and a second outdoor unit 120, which may be connected to a plurality of indoor units 500. Between the first outdoor unit 110 and the plurality of indoor units 500, a first liquid pipe 330 through which the liquid refrigerant can be moved and a first orifice 340 through which the gas refrigerant can be moved may be included. Likewise, between the second outdoor unit 120 and the plurality of indoor units 500, a second liquid pipe 350 through which the liquid refrigerant can be moved and a second engine pipe 360 through which the gas refrigerant can be moved may be included have.

The first liquid pipe 330 and the second liquid pipe 350 may be connected to a common liquid pipe 410. Similarly, the first orifice 340 and the second orifice 360 may be connected to the common orifice 430.

In the indoor unit 500, a branch liquid pipe 530 branched from the common liquid pipe 410 may be installed so that the liquid refrigerant is moved. In addition, the indoor unit 500 may be provided with a branch pipe 540 branching from the common engine 430 so that the gas refrigerant is moved. That is, the branch liquid pipe 530 and the branch pipe 540 may be installed so as to communicate with the common liquid pipe 410 and the common engine 430, respectively.

The branch liquid pipe 530 and the branch pipe 540 can be separately branched from the common liquid pipe 410 and the common pipe 430 by a line distribution method. That is, the branch liquid pipe 530 and the branch pipe 540 are not branched collectively at a certain portion of the common liquid pipe 410 and the common engine 430, And may be connected to the indoor unit 500.

However, the manner in which the plurality of outdoor units 100 and the plurality of indoor units 500 are connected is not limited thereto. For example, it is also possible that the branch liquid pipe 530 and the branch pipe 540 are branched by a head distribution method in which the common liquid pipe 410 and the common engine 430 are collectively branched at a certain portion .

As another example, it is also possible that the line distribution method and the head distribution method are branched by a mixed combination distribution method. That is, depending on the installation environment of the plurality of indoor units 500, the connection method between the plurality of indoor units 500 and the plurality of outdoor units 100 may be different.

The indoor unit 500 may further include an indoor expansion valve 520 for expanding the refrigerant flowing into the indoor unit 500 and an indoor solenoid valve 541 for regulating the flow rate of the refrigerant. Therefore, the plurality of branch liquid pipes 530 and the plurality of branch pipes 540 connected to the indoor unit 500 may have different diameters depending on the capacity of the indoor unit 500.

The outdoor unit 100 may be provided with a main expansion unit 234 for controlling the amount of refrigerant flowing from the plurality of indoor units 500 to the plurality of outdoor units 100 during the heating operation of the air conditioner . The main expansion device 234 may include a first main expansion device 234 installed in the first outdoor unit 110 and a second main expansion unit 235 installed in the second outdoor unit 120 have.

The first main expansion device 234 may be installed at the inlet of the outdoor heat exchanger 200 when the air conditioner is operated in a heating operation on the basis of the first outdoor device 110. The refrigerant flowing through the first liquid pipe 330 and flowing into the first outdoor unit 110 flows into the first main expansion unit 234 through the first liquid pipe 330, And can be introduced into the outdoor heat exchanging apparatus 200.

The first outdoor unit 110 may include a first compressor 150 and the second outdoor unit 120 may include a second compressor 160.

Referring to the first outdoor unit 110, when the air conditioner performs the heating operation, the first compressor 150 can compress the refrigerant into a high-temperature, high-pressure gas state. The refrigerant compressed by the first compressor 150 may be introduced into the indoor unit 500 through the first or second orifice 340 or 360. The refrigerant flowing into the indoor unit 500 may be condensed by the indoor heat exchanger 510 installed in the indoor unit 500 and then introduced into the first outdoor unit 110 along the common liquid pipe 410 .

In this case, a device for controlling the flow rate of the refrigerant flowing from the indoor unit 500 to the first outdoor unit 110 is needed. Accordingly, the first outdoor unit 110 may be provided with a first main expansion unit 234 for controlling the flow rate of the refrigerant.

Similarly, the second outdoor unit 120 may be provided with a second main expansion unit 235 for controlling the flow rate of the refrigerant flowing from the indoor unit 500 to the second outdoor unit 120.

Hereinafter, a method of adjusting the opening degree of the main expansion devices 234 and 235 when the air conditioner performs the heating operation will be described.

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

4, the air conditioner according to the present invention includes a sensing unit 610 for sensing a low pressure of a refrigerant sucked into the first compressor 150 or the second compressor 160, 235 according to the control signal of the control unit 600. The control unit 600 determines whether the main expansion device 234 or 235 is to be opened A main expansion device opening degree adjusting unit 650 for adjusting the opening degree of the main expansion device 650 and a driving unit 630 for driving the control unit 600.

The sensing unit 610 may include a first sensing unit 611 sensing a low pressure of refrigerant drawn into the compressor 150 of the first outdoor unit 110 and a second sensing unit 611 sensed by the compressor 160 of the second outdoor unit 120 And a second sensing unit 612 for sensing the low pressure of the refrigerant. The main expansion device opening degree adjuster 650 includes a first adjuster 651 for adjusting the amount of refrigerant flowing into the first outdoor unit 110 and a second adjuster 651 for adjusting the amount of refrigerant flowing into the second outdoor unit 120 And a second adjustment unit 652.

The controller 600 may determine whether the main expansion device opening controller 650 is operated based on the information detected by the sensing unit 610. The first sensing unit 611 senses the amount of refrigerant flowing into the first outdoor unit 110 and the second sensing unit 612 senses the amount of refrigerant flowing into the second outdoor unit 120 The controller 600 may transmit a control command to operate the first controller 651 or the second controller 652 based on the information about the amount of the refrigerant.

The air conditioner according to the present invention may further include a memory unit 640 in which information on a condition for operating the main expansion device opening degree adjuster 650 is stored in advance. The controller 600 may control whether the main expansion unit opening controller 650 is operated by comparing the information sensed by the sensing unit 610 and information stored in the memory unit 640 in advance.

5 is a flowchart showing a control method of the air conditioner according to the present invention.

Referring to FIG. 5, when the heating operation of the air conditioner is activated, high-temperature and high-pressure gas refrigerant is discharged from the first compressor 150 or the second compressor 160 (S100). When the high-temperature and high-pressure gas refrigerant is discharged from the compressor (150, 160), the refrigerant can harmonize the room air through the outdoor unit (100) and the indoor unit (500).

When the air conditioner is operated for a predetermined time, the sensing unit 610 can sense the pressure of the refrigerant sucked into the compressors 150 and 160 through the indoor unit 500 (S200). The set time refers to the time required for at least the operation of the air conditioner to circulate the refrigerant through the indoor unit 500 and the outdoor unit 100. The setting time may be arbitrarily set by the user or may be set in the memory unit 640 in advance.

The sensing unit 610 may be installed at one side of the plurality of compressors 150 and 160 installed in the plurality of outdoor units 100. The control unit 600 may determine whether there are any compressors 150 and 160 having a set pressure or less based on the information detected by the sensing unit 610 in operation S300.

Specifically, the refrigerant discharged from the outdoor unit 100 flows into the indoor unit 500, and the refrigerant circulating inside the indoor unit 500 can flow into the outdoor unit 100 again. At this time, the plurality of outdoor units 100 are provided with a plurality of compressors 150 and 160, and the pressure of the refrigerant flowing into the plurality of compressors 150 and 160 may be sensed by the sensing unit 610 . Therefore, the controller 600 compares the information about the set pressure stored in the memory 640 with the information sensed by the sensing unit 610, and determines whether or not there is a compressor sensed below the set pressure can do.

If it is determined in step S300 that there is no compressor detected under the set pressure, steps S100 and S100 may be performed again.

On the contrary, if there is a compressor detected at the set pressure or less in step S300, the controller 600 calculates a pressure value sucked into each of the plurality of compressors 150 and 160 (S400). During the heating operation of the air conditioner, the pressure sucked into each of the plurality of compressors (150, 160) may be low.

Specifically, the control unit 600 can calculate the pressure difference between the plurality of compressors. For example, if two outdoor units 110 and 120 are provided and one compressor is installed in each of the outdoor units 100, the refrigerant sucked into the first compressor 150 of the first outdoor unit 110 And the low pressure value of the refrigerant sucked into the second compressor (160) provided in the second outdoor unit (120).

In addition, the total sum of the pressure sucked into the first compressor (150) and the pressure sucked into the second compressor (160) is constant.

Next, the controller 600 may determine whether a pressure difference value between the plurality of compressors 150 and 160 is equal to or greater than a predetermined value (S500). That is, when the suction pressure of the first compressor 150 among the plurality of compressors 150 and 160 is less than the set pressure, the controller 600 compares the difference between the suction pressure of the first compressor 150 and the suction pressure of the first compressor 150 It is possible to determine whether or not the second compressor 160 having a value equal to or greater than the set value exists.

If it is determined in step S500 that the pressure difference between the compressors 150 and 160 is less than the predetermined value, steps S100 and S100 may be performed again.

On the contrary, if the pressure difference between the plurality of compressors 150 and 160 is equal to or greater than the set value in step S500, the controller 600 controls the main expansion device opening degree adjuster 650 to adjust the opening degree of the first main The opening degree of the expansion device 234 or the second main expansion device 235 can be adjusted (S600). Specifically, when comparing the difference with the suction pressure with the first compressor 150, if the second compressor 160 having a value equal to or greater than the set value exists, the controller 600 controls the second compressor 160, (235) of the second main expansion device of the outdoor unit (120).

If the opening degree of the main expansion device is adjusted after the step S600 is finished, the operation of the air conditioner may be performed according to the changed information (S700).

Hereinafter, a method of controlling the opening of the main expansion valve by the controller 600 will be described.

6 is a flowchart specifically illustrating the step S600 of FIG.

In the following, it is assumed that two outdoor units are installed. The first outdoor unit 110 includes a first compressor 150 and a first main expansion unit 234 and the second outdoor unit 120 includes a second compressor 160 and a second main expansion unit 235 ) Are included. Further, it is assumed that the low pressure of the refrigerant sucked into the first compressor 150 is higher than the low pressure of the refrigerant sucked into the second compressor 160.

Referring to FIG. 6, if there is a second compressor 160 having a value greater than a set value when comparing the suction pressure with the first compressor 150, the controller 600 controls the second main expansion device At least one of control for reducing the opening degree of the first main expansion device 235 or control for increasing the opening degree of the first main expansion device 234 can be performed (S610). That is, the control unit 600 may reduce the opening degree of the second main expansion device 235 or extend the opening degree of the first main expansion device 234, 235 and the opening expansion of the first main expansion device 234 may be performed.

When the step S610 is completed, the low pressure of the refrigerant sucked into the second compressor 160 may be reduced (S620). That is, when the opening degree of the second main expansion device 235 is reduced or the opening degree of the first main expansion device 234 is enlarged, the low pressure of the refrigerant sucked into the second compressor 160 can be reduced .

In operation of the air conditioner, the amount of refrigerant flowing into or out of the indoor unit 500 may be uniform. That is, the total sum of the pressure sucked into the first compressor 150 and the pressure sucked into the second compressor 160 is constant.

Accordingly, when the opening degree of the second main expansion device 235 is reduced, the amount of the refrigerant flowing into the second outdoor unit 120 will be reduced and the amount of the refrigerant flowing into the first outdoor unit 110 will increase will be. Accordingly, when the step S620 is completed, the low pressure of the refrigerant sucked into the first compressor 150 may be increased (S630).

Similarly, when the opening degree of the first main expansion device 234 is enlarged, the amount of refrigerant flowing into the first outdoor unit 110 increases and the amount of refrigerant flowing into the second outdoor unit 120 decreases. Accordingly, the low-pressure pressure of the refrigerant sucked into the first compressor 150 can be increased.

That is, by adjusting the opening degree of the second main expansion device 234, the low pressure of the refrigerant sucked into the first compressor 150 and the low pressure of the refrigerant sucked into the second compressor 160 can be uniformly formed have. Therefore, the operating efficiency of the air conditioner can be increased because the low pressure of the refrigerant circulating inside the plurality of outdoor units is uniformly maintained during the heating operation of the air conditioner.

The foregoing description is merely illustrative of the technical idea of the present invention, and various changes and modifications may be made by those skilled in the art without departing from the essential characteristics of the present invention. Therefore, the embodiments disclosed in the present invention are intended to illustrate rather than limit the scope of the present invention, and the scope of the technical idea of the present invention is not limited by these embodiments. The scope of protection of the present invention should be construed according to the following claims, and all technical ideas falling within the scope of the same shall be construed as falling within the scope of the present invention.

100: outdoor unit 200: outdoor heat exchanger
234: first main expansion device 235: second main expansion device
410: common liquid pipe 430: common engine
500: indoor unit 510: indoor heat exchanger
530: branch liquid pipe 540: branch pipe engine
600: control unit 610:
640: Memory part 650: Main expansion device opening degree adjustment part

Claims (13)

A plurality of outdoor units each having a compressor and a main expansion device;
A sensing unit for sensing a low pressure of the refrigerant sucked into the compressor; And
And a controller for recognizing whether or not a first outdoor unit having a low pressure of the refrigerant sensed by the sensing unit is lower than a set pressure,
Wherein,
At least one of the opening degree of the main expansion device of the first outdoor unit or the opening degree of the main expansion device of the second outdoor unit is controlled when the differential pressure between the low pressure of the second outdoor unit and the low pressure of the first outdoor unit is not less than a set value The air conditioner comprising: The method according to claim 1,
Wherein the total sum of the low pressure of the first outdoor unit and the low pressure of the second outdoor unit is constant. 3. The method of claim 2,
If the differential pressure between the low pressure of the second outdoor unit and the low pressure of the first outdoor unit is equal to or higher than the set value,
And the opening degree of the main expansion device of the second outdoor unit is reduced. 3. The method of claim 2,
If the differential pressure between the low pressure of the second outdoor unit and the low pressure of the first outdoor unit is equal to or higher than the set value,
And enlarges the opening of the main expansion device of the first outdoor unit. 3. The method of claim 2,
If the differential pressure between the low pressure of the second outdoor unit and the low pressure of the first outdoor unit is equal to or higher than the set value,
Wherein the opening degree of the main expansion device of the second outdoor unit is reduced and the opening degree of the main expansion device of the first outdoor unit is enlarged. The method according to claim 1,
Wherein the set pressure is defined as a low pressure of a refrigerant sucked into the compressor,
Wherein the set value is defined as a differential pressure between a predetermined low pressure of the first outdoor unit and a predetermined low pressure of the second outdoor unit,
Further comprising a memory unit for storing the preset pressure or the preset value. The method according to claim 1,
Further comprising: a main expansion device opening / closing control part for controlling the opening degree of the main expansion device according to a control command of the control part. A method for controlling an air conditioner including a plurality of outdoor units,
The compressors installed in the plurality of outdoor units are driven for a set time period;
The suction pressure of the compressors is sensed and the magnitude is recognized;
If a suction pressure of the first compressor among the compressors is equal to or lower than a set pressure, recognizing whether a second compressor having a pressure higher than a suction pressure of the first compressor exists; And
And adjusting at least one of an opening of the main expansion device of the outdoor unit having the second compressor or an opening of the main expansion unit of the outdoor unit having the first compressor when the second compressor is present Control method of harmonics. 9. The method of claim 8,
Wherein the sum of the pressure sucked into the first compressor and the pressure sucked into the second compressor is constant. 10. The method of claim 9,
Wherein adjusting the opening of the main expansion device comprises:
Wherein the opening of the main expansion device of the outdoor unit having the second compressor is reduced. 10. The method of claim 9,
Wherein adjusting the opening of the main expansion device comprises:
And expanding the opening of the main expansion device of the outdoor unit having the first compressor. 10. The method of claim 9,
Wherein adjusting the opening of the main expansion device comprises:
A step of reducing the opening degree of the main expansion device of the outdoor unit having the second compressor and enlarging the opening degree of the main expansion device of the outdoor unit having the first compressor. 9. The method of claim 8,
In the stage where the suction pressure of the compressors is sensed and the magnitude is recognized,
Sensing a suction pressure of the first compressor;
Sensing a suction pressure of the second compressor; And
And comparing the suction pressure of the first compressor with the suction pressure of the second compressor.

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