KR20160096947A - An air conditioning system and a method for controlling the same - Google Patents

Abstract

The present invention relates to an air conditioner and a controlling method thereof to easily collect and return oil to a compressor. The air conditioner according to an embodiment of the present invention comprises: the compressor which compresses refrigerant; an outdoor heat exchanger which exchanges heat with outdoor air; an indoor heat exchanger which exchanges heat with indoor air; a flow switch unit which guides the refrigerant compressed in the compressor to the outdoor heat exchanger or the indoor heat exchanger; and a liquid separator which is installed around the inlet of the compressor and supplies gaseous refrigerant to the compressor by separating the gaseous refrigerant from refrigerant vaporized in the outdoor heat exchanger or the indoor heat exchanger. The liquid separator includes: a liquid separating main body which stores refrigerant; and an excessive cooling pipe which is installed in the liquid separating main body and guides the excessive cooling of refrigerant compressed in the outdoor heat exchanger or the indoor heat exchanger.

Description

An air conditioning system and a method for controlling the same

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.

The air conditioner may further include a gas-liquid separator provided at an inlet side of the compressor for separating the gaseous refrigerant from the refrigerant vaporized in the evaporator and supplying the gaseous refrigerant to the compressor. The gas-liquid separator is connected to a suction pipe through which the separated gaseous refrigerant is discharged, and the suction pipe can be extended to the compressor.

In the gas-liquid separator, the refrigerant and the oil may be stored together. The oil is a fluid that performs a lubricating and cooling action of the compressor, and can circulate the refrigeration cycle together with the refrigerant.

For smooth operation of the compressor, the oil needs to be recovered to the compressor. The oil stored in the gas-liquid separator may be recovered to the compressor through a suction line extending to the compressor.

However, in the conventional air conditioner, a layer separation phenomenon occurs between the refrigerant and the oil stored in the gas-liquid separator. Particularly, when the air conditioner performs the heating operation, the evaporation temperature of the refrigerant is formed in a temperature region where the layer separation phenomenon is likely to occur, so that the layer separation phenomenon becomes more serious. Generally, the specific gravity of the oil is smaller than the specific gravity of the refrigerant, so that the oil layer can be formed above the refrigerant layer.

In this way, when the separation of the refrigerant and the oil from the gas-liquid separator occurs in the gas-liquid separator, the recovery of the oil to the compressor is not easy, and oil shortage occurs in the compressor, .

The present applicant has conventionally filed the following application with respect to the structure of the gas-liquid separator.

1. Application number (filing date): 10-2013-0021858 (February 28, 2013)

2. Description of the invention: Accumulator and air conditioner using the same

SUMMARY OF THE INVENTION The present invention has been proposed in order to solve such problems, and it is an object of the present invention to provide an air conditioner and its control method which can easily recover oil from a compressor.

An air conditioner according to an embodiment of the present invention includes: a compressor for compressing a refrigerant; An outdoor heat exchanger for exchanging heat with outdoor air; An indoor heat exchanger for exchanging heat with indoor air; A flow switching unit for guiding the refrigerant compressed in the compressor to the outdoor heat exchanger or the indoor heat exchanger; And a gas-liquid separator provided on a suction side of the compressor for separating the gaseous refrigerant from the refrigerant vaporized in the outdoor heat exchanger or the indoor heat exchanger and supplying the gas-phase refrigerant to the compressor, wherein the gas- main body; And a supercooling pipe installed in the gas-liquid separating main body and guiding a supercooling degree of the refrigerant condensed in the outdoor heat exchanger or the indoor heat exchanger.

The gas-liquid separator may further include an inlet pipe connected to the gas-liquid separating main body and guiding the refrigerant passed through the flow switching portion into the gas-liquid separating main body; And a guide pipe for guiding the flow of the gaseous refrigerant in the refrigerant introduced through the inlet pipe.

The supercooling tube includes a winding portion that is wound at least once to guide heat exchange with the refrigerant in the gas-liquid separation main body.

A first expansion device installed between the outdoor heat exchanger and the gas-liquid separator; And a second expansion device installed between the gas-liquid separator and the indoor heat exchanger.

A first connection pipe connecting the second expansion device and one side of the subcooling pipe; And a fourth connecting pipe connecting the other side of the subcooling pipe and the first expansion device.

A second connection pipe connecting the flow switching unit and the inflow pipe; And a third connection pipe connecting the guide pipe and the compressor.

The bypass pipe may further include a bypass pipe for guiding the refrigerant bypassing the subcooling pipe, wherein the bypass pipe includes a first connection part connected to the first connection pipe; And a second connection part connected to the fourth connection pipe.

The apparatus may further include a first valve installed in the bypass pipe and selectively opening the bypass pipe.

A second valve installed in the first connection pipe for selectively limiting a refrigerant flow to the supercooling pipe; And a third valve installed in the fourth connection pipe for selectively limiting the refrigerant flow to the supercooling pipe.

The second valve is installed at one point of the first connection pipe located between the first connection portion and the subcooling pipe and the third valve is located between the second connection portion and the subcooling pipe The second connecting pipe is installed at one point of the fourth connecting pipe.

The apparatus further includes an evaporation temperature sensor installed in the second connection pipe for sensing the temperature of the refrigerant flowing into the inflow pipe.

The air conditioner includes a compressor, an outdoor heat exchanger, an indoor heat exchanger, and a gas-liquid separator, wherein the compressor is activated, and the refrigerant compressed in the compressor is introduced into the outdoor heat exchanger Condensing in the indoor heat exchanger; Turning on a first valve installed in the bypass pipe so that the condensed refrigerant bypasses the gas-liquid separator; And turning off the second valve and the third valve to restrict the flow of refrigerant to the supercooling pipe installed in the gas-liquid separator.

The gas-liquid separator includes an inlet pipe for guiding the inflow of the refrigerant evaporated in the outdoor heat exchanger or the indoor heat exchanger; And a guide pipe through which the separated gaseous refrigerant flows among the refrigerant introduced from the inlet pipe.

It is further characterized in that whether to open or close the first to third valves is determined based on the evaporation temperature of the refrigerant flowing in the inflow pipe.

When the evaporation temperature of the refrigerant falls within a predetermined temperature range, the first valve is turned off and the second and third valves are turned on.

According to the air conditioner of the present invention, the refrigerant evaporated in the evaporator and the refrigerant condensed in the condenser are heat-exchanged in the gas-liquid separator, so that the ratio of the liquid refrigerant contained in the evaporated refrigerant can be reduced, It is possible to easily recover the oil to the compressor.

Also, since the condensed refrigerant can be supercooled by heat exchange with the evaporated refrigerant, the evaporation ability can be improved.

In addition, since the liquid refrigerant can be evaporated into the gas-phase refrigerant in the gas-liquid separator and introduced into the compressor, the heating performance can be improved as the refrigerant circulation amount increases. Further, sufficient overheating of the refrigerant sucked into the compressor can be ensured, so that the reliability of the compressor can be secured.

1 is a refrigerating cycle diagram of an air conditioner according to a first embodiment of the present invention.
2 is a view showing a configuration of a gas-liquid separator according to a first embodiment of the present invention.
3 is a refrigerating cycle diagram showing a cooling operation of the air conditioner according to the first embodiment of the present invention.
4 is a refrigerating cycle diagram showing a heating operation of the air conditioner according to the first embodiment of the present invention.
5 is a refrigerating cycle diagram of an air conditioner according to a second embodiment of the present invention.
6 is a flow chart showing a control method of the air conditioner according to the second embodiment of the present invention.
7 is a refrigerating cycle diagram showing the cooling operation of the air conditioner according to the second embodiment of the present invention.
8 is a refrigerating cycle diagram showing a heating operation of the air conditioner according to the second 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.

FIG. 1 is a refrigerating cycle diagram of an air conditioner according to a first embodiment of the present invention, and FIG. 2 is a view showing a configuration of a gas-liquid separator according to a first embodiment of the present invention.

1, an air conditioner 10 according to an embodiment of the present invention is provided with a compressor 100 for compressing a refrigerant and a compressor 100 for separating the gaseous refrigerant and liquid refrigerant in the refrigerant from the suction side of the compressor 100 Liquid separator 200 is provided. The gaseous refrigerant separated in the gas-liquid separator 200 can be sucked into the compressor 100.

The air conditioner (10) includes an outdoor heat exchanger (120) and an indoor heat exchanger (140). During the cooling operation of the air conditioner 10, the refrigerant is condensed while passing through the outdoor heat exchanger 120, and can be evaporated while passing through the indoor heat exchanger 140. On the other hand, during the heating operation of the air conditioner 10, the refrigerant can be condensed while passing through the indoor heat exchanger 140, and evaporated while passing through the outdoor heat exchanger 120. Hereinafter, the configuration of the air conditioner will be described on the basis of the cooling operation of the air conditioner 10. Fig.

The air conditioner (10) includes a flow switching unit (110) provided at an outlet side of the compressor (100) for switching the flow direction of the refrigerant. The refrigerant compressed by the compressor 100 may be introduced into the outdoor heat exchanger 120 via the flow switching unit 110 during the cooling operation of the air conditioner 10. [ For example, the flow switching unit 110 may include a four way valve.

The air conditioner 100 includes an outdoor heat exchanger 120 for condensing the refrigerant compressed by the compressor 100 and first and second expansion devices 131 and 135 provided at the outlet side of the outdoor heat exchanger 120 And an indoor heat exchanger 140 provided on an outlet side of the first and second expansion devices 141 and 145 for evaporating the refrigerant.

An outdoor fan 125 for blowing outside air toward the outdoor heat exchanger 120 may be installed at one side of the outdoor heat exchanger 120. An indoor fan 145 for blowing indoor air toward the indoor heat exchanger 140 may be installed at one side of the indoor heat exchanger 140.

The first and second expansion devices 131 and 135 may be installed between the outdoor heat exchanger 120 and the indoor heat exchanger 140. In detail, the first and second expansion devices 131 and 135 are provided with a first expansion device 131 installed between the outdoor heat exchanger 120 and the gas-liquid separator 200 on the basis of the refrigerant passage, And a second expansion device 135 installed between the indoor heat exchanger 200 and the indoor heat exchanger 140.

For example, the first expansion device 131 or the second expansion device 135 may include an electronic expansion valve (EEV) capable of controlling the degree of decompression of the refrigerant by opening degree adjustment.

The first expansion device 131 is fully opened to prevent the refrigerant from leaking during the cooling operation of the air conditioner 10 and the second expansion device 135 is opened at a predetermined opening degree so that the refrigerant is decompressed .

The refrigerant having passed through the first expansion device 131 is heat-exchanged in the gas-liquid separator 200 and then is reduced in pressure by the second expansion device 135. The refrigerant decompressed in the second expansion device (135) may be evaporated in the indoor heat exchanger (140).

The air conditioner 10 is connected to the compressor 100, the gas-liquid separator 200, the outdoor heat exchanger 120, the first and second expansion devices 131 and 135, and the indoor heat exchanger 140, And further includes a refrigerant pipe (50) for guiding the flow.

The air conditioner 10 includes a plurality of connection pipes 151, 152, 153, and 154 that form at least a portion of the refrigerant pipe 50.

Liquid separator 200 and the second expansion unit 135 and the gas-liquid separator 200 to allow the refrigerant to flow into the gas-liquid separator 200, And a first connection pipe 151 for guiding the gas to be discharged from the first connection pipe 151.

For example, during the heating operation of the air conditioner 10, the refrigerant condensed in the indoor heat exchanger 140 may be introduced into the gas-liquid separator 200 through the first connection pipe 151. During the cooling operation of the air conditioner 10, the refrigerant condensed in the outdoor heat exchanger 120 is supercooled by the gas-liquid separator 200, and the gas-liquid separator 200 As shown in FIG.

Liquid separator 200 is provided in the plurality of connection pipes 151, 152, 153 and 154 so as to guide the refrigerant from the flow switching unit 110 to the gas-liquid separator 200, And a connection pipe 152 is included.

Liquid separator 200 and the compressor 100 and a third connection pipe 153 for guiding the refrigerant from the gas-liquid separator 200 to the compressor 100 are provided in the plurality of connection pipes 151, 152, 153, . The third connection pipe 153 may be referred to as a "suction pipe ".

Liquid separator 200 and the refrigerant is introduced into the gas-liquid separator 200 through the first expansion device 131 and the gas-liquid separator 200 in the plurality of connection pipes 151, 152, 153, And a fourth connection pipe 154 for guiding the gas to be discharged from the first connection pipe 154.

For example, during the cooling operation of the air conditioner 10, the refrigerant condensed in the indoor heat exchanger 140 may be introduced into the gas-liquid separator 200 through the fourth connection pipe 154. During the heating operation of the air conditioner 10, the refrigerant condensed in the indoor heat exchanger 140 is supercooled by the gas-liquid separator 200, and the gas-liquid separator 200 As shown in FIG.

2, the gas-liquid separator 200 is provided with a gas-liquid separating main body 210 in which refrigerant is stored, an inlet pipe connected to the gas-liquid separating main body 210 and communicating with the second connecting pipe 152 230).

For example, the inlet pipe 230 may be coupled to the upper portion of the gas-liquid separation body 210 and extend downward by a predetermined length. One end of the inflow pipe 230 forms a second pipe connection part 232 connected to the second connection pipe 152. The other end of the inflow pipe 230 forms a discharge portion 233 for discharging the refrigerant into the gas-liquid separation main body 210.

The gas-liquid separation body 210 is formed with a second coupling portion 212 to which the inlet pipe 230 is coupled.

The gas-liquid separator 200 includes a guide pipe 240 for guiding the discharge of the gaseous refrigerant out of the refrigerant stored in the gas-liquid separator 200. The guide pipe 240 includes a gaseous refrigerant inlet portion 241 through which gaseous refrigerant can flow and a bending portion 245 through which the refrigerant flow direction in the guide pipe 240 is switched. The bending portion 245 forms a lower portion of the guide pipe 240.

For example, the gaseous refrigerant inlet portion 241 forms one end of the guide pipe 240. The gaseous coolant inflow portion 241 may be formed in a direction opposite to the direction in which the discharge portion 233 is formed. Therefore, the refrigerant discharged through the discharge portion 233 can be prevented from flowing into the gaseous refrigerant inflow portion 241.

The guide pipe 240 extends downward from the gaseous coolant inflow portion 241 and is bent upward in the bending portion 245. The guide pipe 240 may extend upward from the bending portion 245 toward the upper portion of the gas-liquid separation body 210.

The guide pipe 240 includes a third pipe connection part 243 connected to the third connection pipe 153. The third pipe connection portion 243 forms the other end of the guide pipe 240.

The gas-liquid separation main body 210 is formed with a third coupling portion 213 to which the guide pipe 240 is coupled.

An oil return hole 246 through which the oil stored in the gas-liquid separator 200 flows is formed in the bending portion 245 of the guide pipe 240. The oil flows into the guide pipe 240 through the oil return hole 246 and flows to the third connecting pipe 153 through the third pipe connecting portion 243 together with the refrigerant.

The gas-liquid separator (200) includes a supercooling pipe (220) for guiding the flow of the refrigerant heat-exchanged with the refrigerant of the guide pipe (240).

The supercooling pipe 220 includes a first pipe connecting portion 221 connected to the first connecting pipe 151 and a fourth pipe connecting portion 222 connected to the fourth connecting pipe 154. The first pipe connection part 221 forms one end of the supercooling pipe 220 and the second pipe connection part 222 forms the other end of the supercooling pipe 220.

The supercooling pipe 220 includes a winding portion 225 to be heat-exchanged with the internal refrigerant of the gas-liquid separator 200. The winding unit 225 forms a lower portion of the supercooling pipe 220 and may be disposed to surround at least a portion of the guide pipe 240. For example, the winding unit 225 may be wound on the outer side of the guide pipe 240 at least once so that the length of the supercooling pipe 220 may be long. The winding portion 225 may be referred to as a "coil heat exchanger ".

The gas-liquid separating main body 210 includes a first coupling portion 211 to which one side of the supercooling pipe 220 is coupled and a second coupling portion 214 to which the other side of the supercooling pipe 220 is coupled . The supercooling pipe 220 is coupled to the first coupling part 211 and extends downward to form a winding part 225. The supercooling pipe 220 extends upward from the winding part 225 to form the fourth coupling part 214 ). ≪ / RTI >

The first to fourth coupling parts 211, 212, 213, and 214 may be formed through the upper surface of the gas-liquid separation body 210.

FIG. 3 is a refrigerating cycle diagram showing a cooling operation of the air conditioner according to the first embodiment of the present invention. FIG. 4 is a diagram illustrating a refrigeration cycle diagram showing a heating operation of the air conditioner according to the first embodiment of the present invention. to be.

3, the refrigerant compressed by the compressor 100 flows into the outdoor heat exchanger 120 through the flow switching unit 110 during the cooling operation of the air conditioner 10, (120) and passes through the first expansion device (131). At this time, the first expansion device 131 is fully opened, so that the refrigerant is not decompressed.

The refrigerant having passed through the first expansion device 131 flows into the supercooling pipe 220 through the fourth connection pipe 154. The refrigerant can be heat-exchanged with the refrigerant in the gas-liquid separator 200 while flowing through the winding part 225.

The refrigerant in the wedging part 225 forms a high temperature and a high pressure than the refrigerant stored in the gas-liquid separator 200 as the condensed refrigerant, so that the refrigerant can be overcooled during the heat exchange process. The liquid refrigerant stored in the gas-liquid separator 200 may be evaporated.

The supercooled refrigerant is discharged from the gas-liquid separator 200 and passes through the second expansion device 135 through the first connection pipe 151. At this time, the second expansion device 135 is opened at a predetermined opening degree to reduce the pressure of the refrigerant.

The refrigerant decompressed in the second expansion device (135) flows into the indoor heat exchanger (140) and can be evaporated. The evaporated refrigerant flows through the second connection pipe 152 through the flow switching unit 110 and flows into the gas-liquid separator 200 through the inlet pipe 230.

The gaseous refrigerant in the refrigerant flowing into the gas-liquid separator 200 flows into the guide pipe 240. On the other hand, the liquid refrigerant stored in the gas-liquid separator 200 can be evaporated by heat exchange with the supercooling tube 220, so that the liquid refrigerant can be phase-changed into the gaseous refrigerant.

As a result, the ratio of the liquid refrigerant in the gas-liquid separator 200 decreases, and the ratio of the gaseous refrigerant becomes relatively large. Therefore, the amount of the refrigerant flowing into the guide pipe 240 can be increased.

Also, since the ratio of the liquid refrigerant is reduced, the liquid separation of the liquid refrigerant and the oil can be prevented, and the oil can be accumulated in the lower part of the gas-liquid separator 200. The oil under the gas-liquid separator 200 may be introduced into the guide pipe 240 through the oil return hole 246.

The gaseous refrigerant and oil in the guide pipe 240 may be sucked into the compressor 100 through the third connection pipe 153.

Part of the liquid refrigerant flowing into the guide pipe 240 together with the oil through the oil return hole 246 is evaporated in the process of flowing through the guide pipe 240 and the third connection pipe 153, Can be sucked into the compressor (100). This refrigerant cycle can be repeated.

4, the refrigerant compressed by the compressor 100 flows into the indoor heat exchanger 140 through the flow switching unit 110 during the heating operation of the air conditioner 10, (140) and passes through the second expansion device (135). At this time, the second expansion device 135 is fully opened, so that the refrigerant is not decompressed.

The refrigerant having passed through the second expansion device (135) flows into the supercooling pipe (220) through the first connection pipe (151). The refrigerant can be heat-exchanged with the refrigerant in the gas-liquid separator 200 while flowing through the winding part 225.

The refrigerant in the wedging part 225 forms a high temperature and a high pressure than the refrigerant stored in the gas-liquid separator 200 as the condensed refrigerant, so that the refrigerant can be overcooled during the heat exchange process. The liquid refrigerant stored in the gas-liquid separator 200 may be evaporated.

The supercooled refrigerant is discharged from the gas-liquid separator 200 and passes through the first expansion device 131 through the fourth connection pipe 154. At this time, the first expansion device 131 is opened at a predetermined opening degree to reduce the pressure of the refrigerant.

The refrigerant decompressed in the first expansion device (131) flows into the outdoor heat exchanger (120) and can be evaporated. The evaporated refrigerant flows through the second connection pipe 152 through the flow switching unit 110 and flows into the gas-liquid separator 200 through the inlet pipe 230.

The gaseous refrigerant in the refrigerant flowing into the gas-liquid separator 200 flows into the guide pipe 240. On the other hand, the liquid refrigerant stored in the gas-liquid separator 200 can be evaporated by heat exchange with the supercooling tube 220, so that the liquid refrigerant can be phase-changed into the gaseous refrigerant.

As a result, the ratio of the liquid refrigerant in the gas-liquid separator 200 decreases, and the ratio of the gaseous refrigerant becomes relatively large. Therefore, the amount of the refrigerant flowing into the guide pipe 240 can be increased.

Also, since the ratio of the liquid refrigerant is reduced, the liquid separation of the liquid refrigerant and the oil can be prevented, and the oil can be accumulated in the lower part of the gas-liquid separator 200. Particularly, the evaporation temperature region of the refrigerant formed in the heating operation can form a temperature region promoting the layer separation phenomenon. In this embodiment, the rate of the liquid refrigerant is reduced, so that the layer separation phenomenon can be prevented.

The oil under the gas-liquid separator 200 may be introduced into the guide pipe 240 through the oil return hole 246. The gaseous refrigerant and oil in the guide pipe 240 may be sucked into the compressor 100 through the third connection pipe 153.

Part of the liquid refrigerant flowing into the guide pipe 240 together with the oil through the oil return hole 246 is evaporated in the process of flowing through the guide pipe 240 and the third connection pipe 153, Can be sucked into the compressor (100). This refrigerant cycle can be repeated.

Hereinafter, a second embodiment of the present invention will be described. Since the present embodiment differs from the first embodiment only in some configurations, the differences will be mainly described, and the description and the reference numerals of the first embodiment are used for the same portions as those in the first embodiment.

5 is a refrigerating cycle diagram of an air conditioner according to a second embodiment of the present invention.

5, the air conditioner 10a according to the second embodiment of the present invention includes a bypass pipe 160 for bypassing a supercooling pipe 220 installed in the gas-liquid separator 200 .

The bypass pipe 160 includes a first connection part 161 connected to the first connection pipe 151 and two connection parts 162 connected to the fourth connection pipe 154.

For example, the refrigerant flowing through the first connection pipe 151 may flow to the bypass pipe 160 through the first connection part 161. The refrigerant flowing through the fourth connection pipe 154 may flow to the bypass pipe 160 through the second connection part 161.

The air conditioner 10a further includes a plurality of valves 171, 172, and 173 installed to control a refrigerant flow of the bypass pipe 160 or a refrigerant flow into the gas-liquid separator 200.

The plurality of valves 171, 172, and 173 include a first valve 171 installed in the bypass pipe 160. For example, the first valve 171 includes a solenoid valve that can be controlled to be selectively turned on / off so that the refrigerant flow in the bypass pipe 160 is selectively performed.

The plurality of valves 171, 172, and 173 further include a second valve 172 installed in the first connection pipe 151. The second valve 172 may be installed at one point of the first connection pipe 151 located between the first connection portion 161 and the first pipe connection portion 221 of the subcooling pipe 220 .

The plurality of valves 171, 172, and 173 include a third valve 173 installed in the fourth connection pipe 154. The third valve 173 is installed at one point of the fourth connection pipe 154 located between the second connection portion 162 and the fourth pipe connection portion 222 of the subcooling pipe 220 .

For example, the second valve 172 or the third valve 173 includes a solenoid valve that can be controlled to be selectively turned on / off so that the refrigerant can be selectively flown in the supercooling pipe 220.

When the first valve 171 is turned off and the second and third valves 172 and 173 are turned on, the refrigerant condensed in the outdoor heat exchanger 120 or the indoor heat exchanger 140 flows into the supercooling pipe 220 . When the first valve 171 is turned on and the second and third valves 172 and 173 are turned off, the refrigerant condensed in the outdoor heat exchanger 120 or the indoor heat exchanger 140 flows through the bypass pipe 160 ). ≪ / RTI >

The air conditioner 10a further includes an evaporation temperature sensor 180 installed in the second connection pipe 152 for sensing the temperature of the evaporated refrigerant. The first to third valves 171, 172, and 173 can be controlled based on the temperature information sensed by the evaporation temperature sensor 180.

FIG. 6 is a flow chart showing a control method of the air conditioner according to the second embodiment of the present invention. FIG. 7 is a refrigerating cycle diagram showing a cooling operation of the air conditioner according to the second embodiment of the present invention. 8 is a refrigerating cycle diagram showing the heating operation of the air conditioner according to the second embodiment of the present invention.

6 to 8, the control method of the air conditioner according to the second embodiment of the present invention will be described.

The air conditioner 10a is turned ON and the compressor 100 can be started. Then, the operation mode of the air conditioner 10a can be recognized (S11).

When the air conditioner 10a operates in the cooling mode, the flow switching unit 110 for the cooling operation can be controlled. The refrigerant compressed in the compressor 100 is condensed in the outdoor heat exchanger 120 and decompressed in the second expansion device 135 under the control of the flow switching unit 110. The refrigerant compressed in the indoor heat exchanger 140 ). ≪ / RTI > Since the refrigerant flow in the inflow pipe 230 and the guide pipe 240 is the same as that in the cooling operation of the first embodiment, detailed description is omitted (S12, S13, S14).

The first valve 171 may be opened or turned on, and the second and third valves 172 and 173 may be closed or turned off. By the control of the valve, the refrigerant flow in the supercooling pipe 220 is restricted, and the refrigerant can flow in the bypass pipe 160 (refer to FIG. 7).

This is because, in the cooling operation, the evaporation temperature of the refrigeration cycle is about 5 ° C or so, and in this temperature range, the refrigerant and oil are mixed well in the gas-liquid separator 200, Do not. This is because the necessity for heat exchange of the refrigerant through the supercooling pipe 220 is reduced.

The refrigerant passing through the bypass pipe 160 flows into the second expansion device 135 through the first connection pipe 151 and is decompressed in the second expansion device 135, 140).

The evaporated refrigerant flows into the second connecting pipe 152 via the flow switching unit 110 and flows into the gas-liquid separator 200 through the inlet pipe 230. The gas-phase refrigerant in the gas-liquid separator 200 may be sucked into the compressor 100 through the guide pipe 240 and the third connection pipe 1563. At this time, the oil in the gas-liquid separator 200 flows into the guide pipe 240 through the oil return hole 146 and can be recovered to the compressor 100 (S15).

On the other hand, when the air conditioner 10a operates in the heating mode, the flow switching unit 110 for the cooling operation can be controlled. The refrigerant compressed in the compressor 100 is condensed in the indoor heat exchanger 140 and decompressed in the first expansion device 131 under the control of the flow switching unit 110 so that the outdoor heat exchanger 120 ). ≪ / RTI > Since the refrigerant flow in the inflow pipe 230 and the guide pipe 240 is the same as that in the heating operation of the first embodiment, detailed description is omitted (S12, S16).

The first valve 171 may be opened or turned on, and the second and third valves 172 and 173 may be closed or turned off. By the control of the valve, the refrigerant flow in the supercooling pipe 220 is restricted, and the refrigerant flow in the bypass pipe 160 can be performed.

With this control state, the cycle can be stabilized when the set time has elapsed. For example, the stabilization of the cycle may be performed such that the variation range of the frequency of the compressor 100 is formed within 3 Hz, the target rotational speed of the outdoor fan 125 and the indoor fan 145 is not changed, , It may mean that the opening degree of the two-stage power devices 131 and 135 is detected to fluctuate within the set pulse (S18).

When the cycle is stabilized, the evaporation temperature of the cycle can be recognized through the evaporation temperature sensor 180 (S19).

When the evaporation temperature is higher than the first set temperature and lower than the second set temperature, the control states of the first to third valves 171, 172, and 173 are changed. In detail, the first valve 171 may be closed or OFF, and the first valve 171 may be opened or ON. By the control of the valve, the refrigerant flow in the bypass pipe 160 is restricted and the refrigerant can be flowed in the supercooling pipe 220.

If the evaporation temperature is higher than the first set temperature and lower than the second set temperature, the mixing of the refrigerant and the oil is limited due to the nature of the oil, and the refrigerant-oil layer separation phenomenon occurs well. Accordingly, the necessity of heat exchange of the refrigerant through the supercooling pipe 220 is increased.

As the condensed refrigerant flows through the supercooling pipe 220, the liquid refrigerant present in the gas-liquid separator 200 is evaporated, thereby preventing the liquid refrigerant from separating from the oil layer (S20 , S21).

On the other hand, if the evaporation temperature is not within the range from the first set temperature to the second set temperature, the control state of the first to third valves 171, 172, 173 is maintained. That is, the first valve 171 may be opened or turned on, and the second and third valves 172 and 173 may be closed or turned off (S22).

The control of the first to third valves 171, 172, and 173 according to the evaporation temperature can be continued in the process of driving the air conditioner 10a. In detail, the evaporation temperature is continuously detected through the evaporation temperature sensor 180, and the sensed information is fed back to a control unit (not shown) of the air conditioner, thereby performing the steps S20 to S22.

According to such a control method, the heat exchange by the supercooling pipe can be selectively performed in the gas-liquid separator based on the evaporation temperature information in the heating operation.

10: air conditioner 50: refrigerant piping
100: compressor 110:
120: outdoor heat exchanger 131: first expansion device
135: second expansion device 140: indoor heat exchanger
151: first connection pipe 152: second connection pipe
153: third connection pipe 154: fourth connection pipe
160: Bypass piping 171: First valve
172: second valve 173: third valve
180: evaporation temperature sensor 200: gas-liquid separator
210: gas-liquid separation body 220: supercooling tube
225: winding portion 230: inlet pipe
240: Guide pipe 245: Bending part
246: Oil return hole

Claims (15)

A compressor for compressing the refrigerant;
An outdoor heat exchanger for exchanging heat with outdoor air;
An indoor heat exchanger for exchanging heat with indoor air;
A flow switching unit for guiding the refrigerant compressed in the compressor to the outdoor heat exchanger or the indoor heat exchanger; And
And a gas-liquid separator provided on a suction side of the compressor for separating the gaseous refrigerant from the refrigerant evaporated in the outdoor heat exchanger or the indoor heat exchanger and supplying the gaseous refrigerant to the compressor,
In the gas-liquid separator,
A gas-liquid separation main body in which refrigerant is stored; And
And a supercooling pipe installed in the gas-liquid separating main body for guiding a supercooling degree of the refrigerant condensed in the outdoor heat exchanger or the indoor heat exchanger. The method according to claim 1,
In the gas-liquid separator,
An inlet pipe connected to the gas-liquid separating main body and guiding the refrigerant passed through the flow switching portion into the gas-liquid separating main body; And
And a guide pipe for guiding the flow of the gaseous refrigerant in the refrigerant introduced through the inlet pipe. The method according to claim 1,
In the supercooling tube,
Wherein at least one winding is carried out at least once, and a winding portion for guiding heat exchange with the refrigerant in the gas-liquid separation main body. 3. The method of claim 2,
A first expansion device installed between the outdoor heat exchanger and the gas-liquid separator; And
And a second expansion device installed between the gas-liquid separator and the indoor heat exchanger. 5. The method of claim 4,
A first connection pipe connecting the second expansion device and one side of the subcooling pipe; And
Further comprising a fourth connecting pipe connecting the other side of the subcooling pipe with the first expansion device. 3. The method of claim 2,
A second connection pipe connecting the flow switching unit and the inflow pipe; And
Further comprising a third connection pipe connecting the guide pipe and the compressor. 6. The method of claim 5,
Further comprising a bypass pipe for guiding the refrigerant to bypass the subcooling pipe,
In the bypass piping,
A first connection unit connected to the first connection pipe; And
And a second connection part connected to the fourth connection pipe. 8. The method of claim 7,
Further comprising a first valve installed in the bypass pipe and selectively opening the bypass pipe. 8. The method of claim 7,
A second valve installed in the first connection pipe for selectively limiting a refrigerant flow to the supercooling pipe; And
Further comprising a third valve installed in the fourth connection pipe for selectively limiting the flow of refrigerant to the supercooling pipe. 10. The method of claim 9,
Wherein the second valve is installed at one point of the first connection pipe located between the first connection portion and the subcooling pipe,
Wherein the third valve is installed at one point of a fourth connecting pipe located between the second connecting portion and the supercooling pipe. The method according to claim 6,
And an evaporation temperature sensor installed in the second connection pipe for sensing the temperature of the refrigerant flowing into the inflow pipe. In an air conditioner including a compressor, an outdoor heat exchanger, an indoor heat exchanger, and a gas-liquid separator,
The compressor is started, and the refrigerant compressed in the compressor is condensed in the outdoor heat exchanger or the indoor heat exchanger;
Turning on a first valve installed in the bypass pipe so that the condensed refrigerant bypasses the gas-liquid separator; And
And turning off the second valve and the third valve to restrict the refrigerant flow to the supercooling pipe installed in the gas-liquid separator. 13. The method of claim 12,
In the gas-liquid separator,
An inlet pipe for guiding the inflow of the refrigerant evaporated in the outdoor heat exchanger or the indoor heat exchanger; And
And a guide pipe through which the separated gaseous refrigerant flows is included in the refrigerant introduced from the inflow pipe. 11. The method of claim 10,
Based on the evaporation temperature of the refrigerant flowing through the inlet pipe,
And determines whether the first to third valves are open or closed. 14. The method of claim 13,
If the evaporation temperature of the refrigerant falls within a preset temperature range,
The first valve is turned OFF, and the second and third valves are turned ON.

Images