KR20140096869A - An air conditioner and a control method the same - Google Patents

Abstract

The present invention relates to an air conditioner and a control method thereof. The air conditioner according to an embodiment of the present invention comprises multiple compressors; a discharge temperature sensors sensing the temperature of a refrigerant discharged from the compressors; a condenser condensing the refrigerant compressed by the compressors; a supercooling heat exchanger supercooling the refrigerant condensed by the condenser; injection flow paths to inject the refrigerant, which exchanges heat in the supercooling heat exchanger, to the compressors; and injection valves installed on the injection flow paths, wherein the opening degrees of the injection valves are controlled based on at least two values of the temperature sensed by the discharge temperature sensors.

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 refrigeration 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 cycle diagram showing a configuration of a conventional air conditioner.

1, the air conditioner 1 is provided with a plurality of compressors 2 and 3, a condenser 4 for condensing the refrigerant compressed by the compressors 2 and 3, (5) for reducing the pressure of the refrigerant condensed in the expansion device (5), and an evaporator (6) for evaporating the refrigerant decompressed in the expansion device (5).

The plurality of compressors (2, 3) includes a first compressor (2) and a second compressor (3) connected in parallel with each other. The refrigerant evaporated in the evaporator (6) is branched into the first compressor (2) and the second compressor (3) and flows in.

The air conditioner (1) includes a temperature sensor (7.8) provided on an outlet side of the plurality of compressors (2, 3) to sense a discharge temperature of the refrigerant. The temperature sensors 7 and 8 are provided with a first temperature sensor 7 disposed on the discharge side of the first compressor 2 and a second temperature sensor 8 disposed on the discharge side of the second compressor 3 .

Generally, the temperature of the refrigerant detected by the first temperature sensor 7 and the second temperature sensor 8 has a similar value. For example, when the types or capacities of the first compressor 2 and the second compressor 3 are similar, the temperature values of the first and second temperature sensors 7 and 8 are recognized as similar.

On the other hand, when the temperature value detected by the first temperature sensor 7 or the second temperature sensor 8 is out of the set range (or the normal range), for example, when the temperature value is higher than the set range, The amount of refrigerant flowing into the first and second compressors (2,3) can be increased by increasing the opening degree of the expansion device (5).

However, when the types or capacities of the first compressor (2) and the second compressor (3) are different, or when any one of the first and second compressors (2, 3) A large deviation may occur in the temperature value detected by the first temperature sensor 7 or the second temperature sensor 8. [

In this case, on the basis of the temperature value of the first temperature sensor 7 or the temperature value of the second temperature sensor 8, based on the temperature value far out of the setting range (or the normal range) As shown in FIG. Then, the discharge temperature of one of the first compressor (2) and the second compressor (3) whose discharge temperature is in an abnormal range can be changed to a normal range.

However, there is a problem in that, according to the opening control of the expansion device 5, the discharge temperature of the other compressor is changed, so that the deviation of the discharge temperature of the first and second compressors 2 and 3 is not reduced .

When the deviation of the discharge temperature is large, the amount of refrigerant flowing into the first and second compressors (2, 3) may be varied, thereby reducing the capacity or operating efficiency of the refrigeration system.

It is an object of the present invention to provide an air conditioner and a control method thereof that can appropriately control the temperature of a refrigerant discharged from a plurality of compressors.

An air conditioner according to an embodiment of the present invention includes: a plurality of compressors; A discharge temperature sensor for sensing the temperature of the refrigerant discharged from the plurality of compressors; A condenser for condensing the refrigerant compressed in the plurality of compressors; A supercooling heat exchanger for supercooling the refrigerant condensed in the condenser; An injection flow path for injecting the refrigerant heat-exchanged in the supercooling heat exchanger into the plurality of compressors; And an injection valve provided in the injection path, wherein the opening degree of the injection valve is adjusted based on at least two temperature values sensed by the discharge temperature sensor.

According to another embodiment of the present invention, there is provided a control method of an air conditioner, comprising: a first compressor and a second compressor are turned on to operate an air conditioner; Injecting a refrigerant having passed through the condenser and the supercooling heat exchanger into the first compressor and the second compressor; Detecting a discharge temperature of the refrigerant discharged from the first compressor and the refrigerant discharged from the second compressor, respectively; And adjusting the amount of refrigerant injected into the first compressor or the second compressor based on the refrigerant discharge temperature of the first compressor and the refrigerant discharge temperature of the second compressor.

According to the present invention, since the refrigerant having passed through the supercooling heat exchanger can be injected into a plurality of compressors, the amount of refrigerant introduced into the compressor can be increased, and thus the capability of the system can be improved.

In addition, since the opening degree of the injection valve can be adjusted based on the temperature of the refrigerant discharged from the plurality of compressors, the temperature deviation of the refrigerant discharged from the plurality of compressors can be maintained within the set range.

In particular, when the discharge temperature of one compressor is high, the opening degree of the injection valve provided for injecting the refrigerant into the one compressor is increased to increase the amount of refrigerant flowing into the one compressor, thereby lowering the discharge temperature of the compressor .

On the other hand, when the discharge temperature of one compressor is low, the opening degree of the injection valve is reduced, and the amount of refrigerant flowing into the one compressor is reduced, thereby increasing the exposure temperature of the one compressor.

In addition, since the opening degree of the injection valve provided at one side of the compressor having the high discharge temperature of the refrigerant can be detected in advance, and the injection valve can be easily selected from among the plurality of injection valves based on the sensed contents, The amount of refrigerant can be effectively controlled.

1 is a cycle diagram showing a configuration of a conventional air conditioner.
2 is a system diagram showing the configuration of an outdoor unit according to an embodiment of the present invention.
3 is a system diagram showing a flow of a refrigerant in an outdoor unit according to an embodiment of the present invention.
4 is a block diagram showing the configuration of an air conditioner according to an embodiment of the present invention.
5 is a flow chart showing a control method of the air conditioner according to the embodiment of the present invention.

Hereinafter, specific embodiments of the present invention will be described with reference to the drawings. It is to be understood, however, that the spirit of the invention is not limited to the embodiments shown and that those skilled in the art, upon reading and understanding the spirit of the invention, may easily suggest other embodiments within the scope of the same concept.

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

Referring to FIG. 2, the air conditioner according to the embodiment of the present invention includes an outdoor unit 10 disposed outdoors and an indoor unit disposed in the room. The indoor unit includes an indoor heat exchanger that exchanges heat with air in the indoor space.

The outdoor unit 10 includes a plurality of compressors 110 and 112 and oil separators 120 and 122 disposed at the outlets of the plurality of compressors 110 and 112 for separating oil from refrigerant discharged from the plurality of compressors 110 and 112, .

The plurality of compressors 110 and 112 include a first compressor 110 and a second compressor 112 connected in parallel.

For example, the first compressor 110 may be a main compressor, and the second compressor 112 may be a sub-compressor. Depending on the capabilities of the system, the second compressor 112 may be further operated if the first compressor 110 is operated first and the capability of the first compressor 110 is insufficient.

As another example, the first compressor 110 and the second compressor 112 may be a compressor operating simultaneously.

The first compressor (110) and the second compressor (112) may be different compressors or may be compressors having different capacities. However, the types or the capacities of the first and second compressors 110 and 112 are not limited to any one.

The oil separators 120 and 122 include a first oil separator 120 disposed at an outlet side of the first compressor 110 and a second oil separator 122 disposed at an outlet side of the second compressor 112 .

The outdoor unit (10) includes a recovery flow path (116) for recovering oil from the oil separators (120, 122) to the compressors (110, 112). That is, the recovery flow path 116 extends from the first oil separator 120 to the first compressor 110 and from the second oil separator 122 to the second compressor 112.

Temperature sensors (171, 172) for sensing the temperature of the refrigerant discharged from the compressor are provided at the outlet sides of the first compressor (110) and the second compressor (112). The temperature sensors 171 and 172 are provided with a first discharge temperature sensor 171 disposed at the outlet side of the first compressor 110 and a second discharge temperature sensor 172 disposed at the outlet side of the second compressor 112 ).

A high pressure sensor 125 for sensing a discharge high pressure of the refrigerant discharged from the compressors 110 and 112 and a refrigerant passing through the high pressure sensor 125 are connected to the outlet of the oil separators 120 and 122, The flow switching unit 130 is provided.

When the air conditioner is in the cooling operation mode, the refrigerant flows into the outdoor heat exchanger (140) from the flow switching unit (130). 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 outdoor heat exchanger (140) includes a plurality of heat exchangers (141, 142) and an outdoor fan (143). The plurality of heat exchanging units 141 and 142 include a first heat exchanging unit 141 and a second heat exchanging unit 142 connected in parallel.

The outdoor heat exchanger 140 includes a variable flow passage 144 for guiding the flow of the refrigerant from the outlet side of the first heat exchange section 141 to the inlet side of the second heat exchange section 142. The variable flow path 144 extends from the outlet side piping of the first heat exchange section 141 to the inlet side piping of the second heat exchange section 142.

The outdoor heat exchanger (140) is provided with a variable valve (145) provided on the variable flow path (144) to selectively block the flow of the refrigerant. Depending on whether the variable valve 145 is turned on or off, the refrigerant that has passed through the first heat exchanging unit 141 may be selectively introduced into the second heat exchanging unit 142.

More specifically, when the variable valve 145 is opened or opened, the refrigerant having passed through the first heat exchanging unit 141 flows into the second heat exchanging unit 142 through the variable flow path 144. At this time, the first outdoor valve 146 provided at the outlet side of the first heat exchanging unit 141 may be closed.

A second outdoor valve 147 is provided on the outlet side of the second heat exchanging unit 142. The refrigerant heat-exchanged in the second heat exchanging unit 142 flows through the second outdoor valve 147, (150). ≪ / RTI >

On the other hand, when the variable valve 145 is turned off or closed, the refrigerant having passed through the first heat exchanging unit 141 may be introduced into the supercooling heat exchanger 150 through the first outdoor valve 146 .

Here, the first outdoor valve 146 and the second outdoor valve 147 may be arranged in parallel corresponding to the arrangement of the first and second heat exchange units 141 and 142.

A supercooling heat exchanger (150) is disposed at the outlet side of the outdoor heat exchanger (140). When the air conditioner is in the cooling operation mode, the refrigerant that has passed through the outdoor heat exchanger (140) may be introduced into the supercooling heat exchanger (150).

The supercooling heat exchanger 150 can be understood as an intermediate heat exchanger in which a first refrigerant circulating in the refrigerant system and a refrigerant (a second refrigerant) in the refrigerant are branched and then heat-exchanged. The first refrigerant may be a "main refrigerant" circulating the system, and the second refrigerant may be a "branched refrigerant"

The outdoor unit (10) includes a supercooling oil passage (151) through which the second refrigerant is branched. The supercooling oil passage 151 is provided with a supercooling expansion device 153 for reducing the pressure of the second refrigerant.

Depending on the degree of opening of the supercooling expansion device 153, the amount of refrigerant flowing through the supercooling flow path 151 may be varied. The supercooling expansion device 153 may include an electric expansion valve (EEV).

The supercooling flow path 151 is provided with a plurality of temperature sensors 154a and 154b. The plurality of temperature sensors 154a and 154b are connected to a first subcooling sensor 154a for sensing the temperature of the refrigerant before being introduced into the subcooling heat exchanger 150 and a second subcooling sensor 154b for detecting the temperature of the refrigerant after passing through the subcooling heat exchanger 150 And a second supercooling sensor 154b for sensing the temperature.

During the heat exchange of the first refrigerant and the second refrigerant in the supercooling heat exchanger 150, the first refrigerant may be over-condensed or sub-cooled, and the second refrigerant may be heated or overheated.

The "superheat degree" of the second refrigerant can be recognized based on the temperature values of the refrigerant sensed by the first supercooling sensor 154a and the second supercooling sensor 154b, respectively. For example, a value obtained by subtracting the temperature sensed by the first subcooling sensor 154a from the temperature sensed by the second subcooling sensor 154b may be recognized as the "superheat degree ".

Depending on the opening degree of the supercooling expansion device 153, the degree of superheat may vary. For example, if the opening degree of the supercooling expansion device 153 is reduced and the amount of the refrigerant flowing in the supercooling flow path 151 is small, the degree of superheat can be increased. On the other hand, if the degree of opening of the supercooling expansion device 153 increases to increase the amount of refrigerant flowing through the supercooling flow path 151, the degree of superheat can be reduced.

The second refrigerant heat-exchanged in the supercooling heat exchanger (150) may be introduced into the gas-liquid separator (160) or the compressors (110, 112).

The gas-liquid separator 160 separates the gaseous refrigerant before the refrigerant flows into the compressors 110 and 112. In detail, the gaseous refrigerant in the refrigerant flowing into the gas-liquid separator 160 through the low-pressure passage 160a can be sucked into the compressors 110 and 112 via the suction passage 160b.

The refrigerant flowing in the suction passage 160b may be branched into the first compressor 110 and the second compressor 112 and flow. The pressure of the refrigerant sucked into the compressors 110 and 112 (hereinafter, suction pressure) is formed at a low pressure.

Specifically, the supercooling passage 151 is branched into a first guide passage 155 for guiding the refrigerant to the gas-liquid separator 160 and a second guide passage 157 for guiding the refrigerant to the gas-liquid separator 160 and the compressors 110 and 112.

The first guide passage 155 is connected to the low-pressure passage 160a.

The first guide passage (155) is provided with a supercooling bypass valve (156) for selectively blocking the flow of the refrigerant. The amount of the refrigerant flowing into the gas-liquid separator 160 can be adjusted according to on / off or opening of the supercooling bypass valve 156.

The second guide passage (157) extends from the supercooling passage (151) to the compressors (110, 112).

In detail, the second guide passage 157 is provided with a first injection passage 158a for injecting refrigerant into the first compressor 110 and a second injection passage 158a for injecting the refrigerant into the second compressor 112, And a branched portion 157a for branching the first injection path 158a and the second injection path 158b.

The second guide passage 157 is provided with injection valves 159a and 159b capable of controlling the amount of refrigerant injected into the compressors 110 and 112. The injection valves 159a and 159b include a first injection valve 159a provided in the first injection path 158a and a second injection valve 159b provided in the second injection path 158b .

EEV may be included in the injection valves 159a and 159b. The amount of the refrigerant injected into the compressors 110 and 112 can be adjusted according to on / off or opening of the first and second injection valves 159a and 159b.

In summary, the second refrigerant heat-exchanged in the supercool heat exchanger 150 may be injected into the compressors 110 and 112 through the first injection path 158a and the second injection path 158b.

The pressure of the injected refrigerant is higher than the suction pressure of the compressors 110 and 112 and may form an intermediate pressure lower than the pressure discharged from the compressors 110 and 112 (hereinafter referred to as a discharge pressure). The discharge pressure may be a pressure sensed by the high-pressure sensor 125.

The outdoor unit 10 is provided with a receiver 162 for storing at least a portion of the first refrigerant that has passed through the supercooling heat exchanger 150 and a receiver 162 branched from the outlet of the supercooling heat exchanger 150 by the receiver 162 And a receiver inlet flow passage 163 for guiding the flow of the refrigerant.

The receiver 162 may be coupled to the gas-liquid separator 160. That is, the receiver 162 and the gas-liquid separator 160 may be partitioned inside the refrigerant storage tank. For example, the gas-liquid separator 160 is provided at an upper portion of the refrigerant storage tank, and the receiver 162 is provided at a lower portion thereof.

The receiver inlet flow passage 163 is provided with a receiver inlet valve 164 for controlling the flow of the refrigerant. When the receiver inlet valve 164 is opened, at least a portion of the refrigerant in the first refrigerant may flow into the receiver 162. The receiver inlet flow passage 163 is provided with a pressure reducing device to reduce the pressure of the refrigerant flowing into the receiver 162.

To the receiver 162, a receiver outlet pipe 165 is connected. The receiver outlet pipe 165 may extend to the gas-liquid separator 160. At least a portion of the refrigerant stored in the receiver 162 may be introduced into the gas-liquid separator 160 through the receiver outlet pipe 165.

The receiver outlet pipe 165 is provided with a receiver outlet valve 166 capable of regulating the amount of refrigerant discharged from the receiver 162. The amount of refrigerant flowing into the gas-liquid separator 160 can be adjusted according to on / off or opening of the receiver outlet valve 166.

Meanwhile, the first refrigerant passing through the supercooling heat exchanger 150 may be introduced into the indoor unit through the connection pipe 195.

3 is a system diagram showing a flow of a refrigerant in an outdoor unit according to an embodiment of the present invention. The refrigerant flow according to the present embodiment will be briefly described with reference to FIG.

Hereinafter, the air conditioner according to the embodiment of the present invention performs cooling operation. However, even when the air conditioner performs the heating operation, there is only a difference in that the refrigerant passing through the compressor is condensed in the indoor heat exchanger and evaporated in the outdoor heat exchanger, and the phenomenon in which the refrigerant passing through the supercooling heat exchanger is injected into the compressor is the same. The main idea of the invention may be equally applied to the heating operation.

The gaseous refrigerant separated from the gas-liquid separator 160 may be introduced into the first compressor 110 and the second compressor 112 through the suction passage 160b.

The high-temperature and high-pressure refrigerant in the first compressor (110) and the second compressor (112) is condensed in the outdoor heat exchanger (140) and then flows into the supercooling heat exchanger (150). That is, the first refrigerant circulating in the system and the second refrigerant branched from the first refrigerant are heat-exchanged in the supercooling heat exchanger (150).

At this time, depending on the opening degree of the supercooling expansion device 153, the degree of superheat of the refrigerant or the amount of refrigerant flowing through the supercooling flow path 151 may be adjusted.

The refrigerant flowing through the supercooling passage 151 can flow into the first injection passage 158a and the second injection passage 158b. The amount of the refrigerant injected into the first compressor 110 or the second compressor 112 may vary depending on the on / off or opening of the first injection valve 159a or the second injection valve 159b.

FIG. 4 is a block diagram showing the configuration of an air conditioner according to an embodiment of the present invention, and FIG. 5 is a flow chart showing a method of controlling an air conditioner according to an embodiment of the present invention.

4, the air conditioner 10 according to the embodiment of the present invention may be provided with a supercooling heat exchanger 150 having a temperature before the refrigerant flowing in the supercooling flow path 151 flows into the supercooling heat exchanger 150 And a second supercooling degree sensor 154b for sensing the temperature of the supercooling heat exchanger 150 after flowing out from the supercooling heat exchanger 150 (hereinafter, referred to as " supercooling outlet temperature ").

The air conditioner (10) further includes a supercooling expansion device (153) capable of adjusting opening degree in order to control the degree of superheat or the amount of refrigerant flowing through the supercooling flow path (151).

The control unit 200 can recognize the degree of superheat of the refrigerant passing through the supercooling heat exchanger 150 based on the temperature values sensed by the first and second supercooling sensors 154a and 154b.

The controller 200 may control the degree of superheat by adjusting the opening degree of the supercooling expansion device 153. When the amount of refrigerant is reduced by decreasing the opening degree of the supercooling expansion device 153, the degree of superheat increases, and when the amount of refrigerant increases, the superheating degree may decrease.

The air conditioner 10 is provided with a first discharge temperature sensor 171 for detecting a discharge refrigerant temperature (first discharge temperature) of the first compressor 110 and a discharge temperature sensor 171 for detecting a discharge refrigerant temperature And a second discharge temperature sensor 172 for detecting the second discharge temperature.

The air conditioner 10 is further provided with a first injection valve 130 capable of controlling the amount of refrigerant injected into the first compressor 110 based on the temperature detected by the first and second discharge temperature sensors 171 and 172, (159a) and a second injection valve (159b) capable of controlling the amount of refrigerant injected into the second compressor (112).

The controller 200 may control whether the first and second injection valves 159a and 159b are on or off.

Hereinafter, a control method of the air conditioner according to the present embodiment will be described with reference to FIG.

The first compressor 110 and the second compressor 112 are driven, and the air conditioner 10 can start cooling or heating operation. The cooling system of the air conditioner can be stabilized when the set time has elapsed after the air conditioner enters into operation.

Here, the term "stabilization" may mean a case where a high pressure (discharge pressure of the compressor) and a low pressure (evaporation pressure of the evaporator) constituting an appropriate level constituting the refrigeration cycle are formed. For example, the system may be stabilized after 2 minutes have elapsed since the operation of the air conditioner started (S11).

During the operation of the air conditioner 10, the refrigerant that has passed through the supercooling passage 151 through the supercooling heat exchanger 150 may be injected into the first compressor 110 and the second compressor 112 .

In detail, when the first injection valve 159a is opened, the refrigerant is injected into the first compressor 110 through the first injection channel 158a. When the second injection valve 159b is opened, the refrigerant is injected into the second compressor 112 through the second injection passage 158b (S12).

On the other hand, the degree of superheat of the refrigerant or the amount of the refrigerant flowing into the first injection path 158a and the second injection path 158b can be controlled by adjusting the opening degree of the supercooling expansion device 153.

That is, as the opening degree of the supercooling expansion device 153 increases, the amount of the refrigerant flowing into the first injection path 158a and the second injection path 158b increases and the degree of superheat of the refrigerant can be reduced (S13).

The discharge temperatures of the first compressor 110 and the second compressor 112 may be sensed through the first discharge temperature sensor 171 and the second discharge temperature sensor 172 (S14).

The discharge temperature deviations of the first and second compressors 110 and 112 can be recognized based on the sensed discharge temperature information of the first compressor 110 and the second compressor 112. [ The "discharge temperature deviation" may be understood as a value obtained by subtracting a low discharge temperature from a discharge temperature of the first compressor 110 and the second compressor 112 at a high discharge temperature.

It is recognized whether or not the discharge temperature deviation is equal to or higher than the set temperature DELTA T1. It is understood that the discharge temperature difference between the first compressor 110 and the second compressor 112 is abnormally excessive if the discharge temperature deviation is equal to or higher than the set temperature.

When the discharge temperature deviation is equal to or higher than the set temperature, the opening degree of the injection valve corresponding to (or connected to) the compressor having the high discharge temperature among the discharge temperatures of the first compressor 110 and the second compressor is recognized. On the other hand, if the discharge temperature deviation is smaller than the set temperature, steps S12 and subsequent steps are performed again.

For example, when the discharge temperature of the first compressor 110 is higher than the discharge temperature of the second compressor by a predetermined temperature or more, the current opening degree of the first injection valve 159a is recognized (S15, S16).

That is, in the above example, whether the current opening degree of the first injection valve 159a is equal to or greater than the set opening degree is recognized. The "set opening degree" may be determined as a reference value for determining whether opening degree adjustment of the first injection valve 159a is easy, that is, whether or not opening degree increase is possible. Here, the reference value may be a predetermined frequency.

For example, the setting degree may be the maximum opening degree of the first injection valve 159a, that is, the opening degree of the fully opened state (S17).

If the opening degree of the first injection valve 159a is equal to or greater than the set opening degree, the increase in the opening degree of the first injection valve 159a is restricted. Accordingly, the opening degree of the second injection valve 159b corresponding to the second compressor 112 in the above-described example is regulated.

In other words, the opening of the second injection valve 159b is reduced. When the opening degree of the second injection valve 159b is reduced, the amount of the refrigerant injected into the second compressor 112 is reduced, and the temperature of the refrigerant discharged from the second compressor 112 relatively increases (S18).

On the other hand, if the opening degree of the injection valve of the compressor having the high discharge temperature is lower than the set opening degree in step S17, the injection valve of the compressor having the high discharge temperature, that is, the first injection valve corresponding to the first compressor The degree of opening of the opening 159a is increased.

As a result, the amount of the refrigerant that has passed through the first injection valve 159a is increased to increase the amount of the refrigerant injected into the first compressor 110, The temperature is decreased (S19).

In this way, when the deviation of the discharge temperature of the first and second compressors is abnormally large, it is attempted to control the amount of the injected refrigerant of the compressor whose discharge temperature is high first. If such control is not possible, the amount of the injected refrigerant of the compressor whose discharge temperature is low .

According to such a control method, it is possible to control the temperature of the refrigerant discharged from the plurality of compressors to be within a predetermined range, thereby preventing the refrigerant discharge temperature of the compressor from becoming abnormally high, thereby preventing damage to the compressor .

10: outdoor unit 110, 112: compressor
125: high-pressure sensor 130:
140: outdoor heat exchanger 150: supercooling heat exchanger
151: supercooling flow path 153: supercooling expansion device
154a: first subcooling sensor 154b: second subcooling sensor
158a: first injection channel 158b: second injection channel
159a: first injection valve 159b: second injection valve
160: gas-liquid separator 162: receiver
171: first discharge temperature sensor 172: second discharge temperature sensor

Claims (13)

A plurality of compressors;
A discharge temperature sensor for sensing the temperature of the refrigerant discharged from the plurality of compressors;
A condenser for condensing the refrigerant compressed in the plurality of compressors;
A supercooling heat exchanger for supercooling the refrigerant condensed in the condenser;
An injection flow path for injecting the refrigerant heat-exchanged in the supercooling heat exchanger into the plurality of compressors; And
An injection valve provided in the injection channel,
Wherein the opening degree of the injection valve is adjusted based on at least two temperature values sensed by the discharge temperature sensor. The method according to claim 1,
Wherein the plurality of compressors include a first compressor and a second compressor,
In the discharge temperature sensor,
A first discharge temperature sensor disposed at an outlet side of the first compressor; And
And a second discharge temperature sensor disposed at an outlet side of the second compressor. 3. The method of claim 2,
Further comprising a control unit for adjusting an opening degree of the injection valve based on a difference between temperature values sensed by the first discharge temperature sensor and the second discharge temperature sensor. The method of claim 3,
In the injection valve,
A first injection valve controlled to inject a refrigerant into the first compressor and a second injection valve controlled to inject a refrigerant into the second compressor,
Wherein,
And adjusts the opening degree of the first injection valve or the second injection valve when the temperature difference becomes equal to or greater than a set value. 5. The method of claim 4,
When the temperature difference becomes equal to or greater than a set value,
And detects an opening degree of one injection valve corresponding to a compressor having a high discharge temperature among the first compressor and the second compressor. 6. The method of claim 5,
If the opening degree of the injection valve is equal to or greater than the set opening degree, the control unit.
And the opening degree of the ejection valve corresponding to the compressor having a low discharge temperature is reduced. 6. The method of claim 5,
If the opening degree of the injection valve is smaller than the set opening degree,
And increases the opening degree of the injection valve. The method according to claim 1,
A supercooling oil passage for guiding the flow of the refrigerant to the supercooling heat exchanger; And
Further comprising a supercooling expansion device provided in the supercooling flow path and controlling an amount of superheat or an amount of refrigerant flowing into the supercooling heat exchanger. The first compressor and the second compressor are turned on to operate the air conditioner;
Injecting a refrigerant having passed through the condenser and the supercooling heat exchanger into the first compressor and the second compressor;
Detecting a discharge temperature of the refrigerant discharged from the first compressor and the refrigerant discharged from the second compressor, respectively; And
And adjusting the amount of refrigerant injected into the first compressor or the second compressor based on the information on the refrigerant discharge temperature of the first compressor and the refrigerant discharge temperature of the second compressor Control method. 10. The method of claim 9,
In the information,
And a refrigerant discharge temperature of the first compressor and a refrigerant discharge temperature of the second compressor. 11. The method of claim 10,
If the deviation value is equal to or larger than the set value,
Further comprising the step of recognizing an opening value of an injection valve connected to a compressor having a higher refrigerant discharge temperature among the first compressor and the second compressor. 12. The method of claim 11,
If the opening value of the injection valve is equal to or greater than the set opening degree,
Further comprising the step of reducing the opening degree of the injection valve connected to the compressor having a low refrigerant discharge temperature. 12. The method of claim 11,
If the opening value of the one injection valve is less than the set opening degree,
Further comprising the step of increasing the opening degree of the injection valve.

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