KR102207263B1 - 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.
An air conditioner according to an embodiment of the present invention includes: a compressor for compressing a refrigerant to a high pressure; A low pressure sensor that senses a low pressure of the refrigerant sucked into the compressor; A condenser for condensing the refrigerant compressed by the compressor; An intermediate heat exchanger for heat exchange of the refrigerant condensed in the condenser; An injection flow path for injecting the refrigerant heat-exchanged in the intermediate heat exchanger to the compressor; And a bypass flow path that communicates with the injection flow path and guides the high-pressure gas refrigerant of the compressor to the suction side of the compressor, and refrigerant to the compressor through the injection flow path based on information detected by the low pressure sensor. It characterized in that it selectively performs injection or bypass flow of the refrigerant through the bypass flow path.

Description

An air conditioner and a control method the same}

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

An air conditioner is a device for maintaining the air in a predetermined space in the most suitable state according to the use and purpose. In general, the air conditioner includes a compressor, a condenser, an expansion device, and an evaporator, and a refrigeration cycle for compressing, condensing, expanding, and evaporating a refrigerant is driven to cool or heat the predetermined space. .

The predetermined space may be proposed in various ways depending on the location where the air conditioner is used. For example, when the air conditioner is disposed in a home or office, the predetermined space may be an indoor space of a house or building. On the other hand, when the air conditioner is disposed in a vehicle, the predetermined space may be a boarding space for a person to ride.

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

Meanwhile, the air conditioner may be provided with a heat exchanger and a valve device for injecting a refrigerant into a compressor. Regarding the injection structure of the refrigerant, the present applicant has filed the following application.

[Prior literature]

1. Application No. 10-2012-0018354 (Publication date: September 2, 2013), Title of invention: Air conditioner.

However, according to the air conditioner of the prior literature, when the outside air is in a low-temperature state, the low pressure of the refrigerant cycle is excessively lowered, thereby increasing the load of the compressor and reducing the operating efficiency of the system.

The present invention has been proposed to solve such a problem, and an object of the present invention is to provide an air conditioner capable of maintaining a low pressure even in a low temperature environment and a control method thereof.

An air conditioner according to an embodiment of the present invention includes: a compressor for compressing a refrigerant to a high pressure; A low pressure sensor that senses a low pressure of the refrigerant sucked into the compressor; A condenser for condensing the refrigerant compressed by the compressor; An intermediate heat exchanger for heat exchange of the refrigerant condensed in the condenser; An injection flow path for injecting the refrigerant heat-exchanged in the intermediate heat exchanger to the compressor; And a bypass flow path that communicates with the injection flow path and guides the high-pressure gas refrigerant of the compressor to the suction side of the compressor, and refrigerant to the compressor through the injection flow path based on information detected by the low pressure sensor. It characterized in that it selectively performs injection or bypass flow of the refrigerant through the bypass flow path.

In addition, in the bypass flow path, a bypass valve that is opened when the low pressure detected by the low pressure sensor is less than or equal to the first set pressure is installed.

In addition, in the injection flow path, an injection valve that opens when the low pressure detected by the low pressure sensor is less than or equal to the first set pressure is installed.

In addition, when the low pressure sensed by the low pressure sensor is greater than or equal to the second set pressure greater than the first set pressure, the bypass valve is closed and the injection valve is opened.

In addition, the intermediate heat exchanger includes a first intermediate heat exchanger and a second intermediate heat exchanger connected in series with each other.

In addition, the injection flow path includes: a first injection flow path extending from an outlet side of the first intermediate heat exchanger to a first injection port of the compressor to inject a refrigerant; And a second injection passage extending from an outlet side of the second intermediate heat exchanger to a second injection port of the compressor to inject a refrigerant.

In addition, an injection expansion device for decompressing the refrigerant flowing into the first intermediate heat exchanger; And a supercooling expansion device that depressurizes the refrigerant flowing into the second intermediate heat exchanger and is closed when the low pressure sensed by the low pressure sensor is less than or equal to the first set pressure.

Further, a branch portion provided at an outlet side of the second intermediate heat exchanger is further included, and the bypass flow path and the second injection flow path are branched from the branch portion.

In addition, a gas-liquid separator provided at an inlet side of the compressor and separating a gaseous refrigerant from among refrigerants; A low pressure pipe guiding the inflow of the refrigerant into the gas-liquid separator; And a suction pipe for guiding the gaseous refrigerant separated by the gas-liquid separator to the compressor.

In addition, the bypass flow path is connected to the low pressure flow path.

In addition, an injection flow control unit capable of on/off control is installed in the first injection flow path.

A method for controlling an air conditioner according to another aspect includes the steps of: a compressor is driven to perform a normal heating operation; Sensing a low pressure of the refrigerant sucked into the compressor; And if the low pressure of the refrigerant is less than or equal to the first set pressure, performing a heating operation corresponding to the low pressure. In the step of performing the heating operation corresponding to the low pressure, an injection flow path through which the refrigerant can be injected into the compressor is opened. step; And opening a bypass flow path extending from the injection flow path to a suction side of the compressor.

In addition, when the injection flow path is opened, the high-pressure gas refrigerant of the compressor flows to the suction side of the compressor via the injection flow path and the bypass flow path.

In addition, when the low pressure of the refrigerant is equal to or greater than the second set pressure, the normal heating operation is performed.

In addition, the second set pressure is characterized in that higher than the first set pressure.

According to the present invention, the high pressure gas refrigerant (hot gas refrigerant) of the compressor is bypassed (hot gas bypass control) to the low pressure side of the system, so that the low pressure of the system excessively decreases even when the temperature of the outside air is low during heating operation. There is an effect that you can prevent it.

In addition, there is an advantage that the load of the compressor is reduced by preventing the low pressure of the system from falling, and the high pressure of the system can be formed within a desired range.

In addition, since it is possible to determine whether or not to control the bypass of the hot gas refrigerant by detecting the low pressure of the system and comparing the detected low pressure with the set pressure, it is easy to control the refrigerant injection to the compressor along with the bypass control of the hot gas refrigerant. The advantage is that it can be performed.

In addition, there is an advantage in that the amount of circulating refrigerant in the system can be increased and heating performance can be improved by continuously injecting the refrigerant through the injection flow path during the heating operation.

In addition, during the cooling operation, it is possible to secure an additional degree of subcooling through the first and second heat exchangers.

1 is a system diagram showing the configuration of an air conditioner according to a first embodiment of the present invention.
2 is a flow chart showing a control method of an air conditioner according to the first embodiment of the present invention.
3 is a system diagram showing a refrigerant flow state during a normal heating operation of the air conditioner according to the first embodiment of the present invention.
4 is a system diagram showing the flow of refrigerant during a low-pressure heating operation of the air conditioner according to the first embodiment of the present invention.
5 is a system diagram showing the configuration of an air conditioner according to a second embodiment of the present invention.

Hereinafter, specific embodiments of the present invention will be described with reference to the drawings. However, the spirit of the present invention is not limited to the presented embodiments, and those skilled in the art who understand the spirit of the present invention will be able to easily propose other embodiments within the scope of the same idea.

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

Referring to FIG. 1, an air conditioner 10 according to an exemplary embodiment of the present invention includes an outdoor unit 100 disposed outdoors and an indoor unit disposed indoors. The indoor unit includes an indoor heat exchanger that exchanges heat with air in an indoor space.

The outdoor unit 100 includes a plurality of compressors (110, 112), and an oil separator (120, 122) disposed at an outlet side of the plurality of compressors (110, 112) and for separating oil from refrigerants discharged from the plurality of compressors (110, 112). Is included.

The plurality of compressors 110 and 112 includes a first compressor 110 and a second compressor 112 connected in parallel. 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 first compressor 110 is operated first, and if the capability of the first compressor 110 is insufficient, the second compressor 112 may be additionally operated. For example, the first compressor 110 and the second compressor 112 may include an inverter compressor.

At the outlet side of the first compressor 110 and the second compressor 112, a first discharge temperature sensor 115 and a second discharge temperature sensor for sensing the temperature of the refrigerant compressed by the first and second compressors (119, 112) 116 is installed.

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. Included.

In the outdoor unit 100, a first recovery flow path 111 and a second recovery flow path 113 for respectively recovering oil from the first and second oil separators 120 and 122 to the first and second compressors 110 and 112 are provided. Included. That is, the first recovery flow path 111 extends from the first oil separator 120 to the first compressor 110, and the second recovery flow path 113 is formed from the second oil separator 122. It extends to the second compressor 112.

Check valves for guiding a one-way flow of refrigerant from the first and second oil separators 120 and 122 to the first and second compressors 110 and 112 may be installed in the first and second recovery passages 111 and 113, respectively.

At the outlet side of the first and second oil separators 120 and 122, a high pressure sensor 125 for sensing the discharge high pressure of the refrigerant discharged from the compressors 110 and 112 and the refrigerant passing through the high pressure sensor 125 are supplied with an outdoor heat exchange device ( 140) or a flow conversion unit 130 that guides toward the indoor unit is provided.

When the air conditioner operates for cooling, the refrigerant flows into the outdoor heat exchange device 140 from the flow conversion unit 130. On the other hand, when the air conditioner operates for heating, the refrigerant flows from the flow conversion unit 130 to the indoor heat exchanger side of the indoor unit through the engine 196.

The outdoor heat exchange device 140 includes a plurality of heat exchange units 141 and 142 and an outdoor fan 143. The plurality of heat exchange units 141 and 142 include a first heat exchange unit 141 and a second heat exchange unit 142 connected in parallel. The refrigerant that has passed through the flow conversion unit 130 is limited to flow to the second heat exchange unit 142 by a check valve 145a, and may flow into the first heat exchange unit 141.

The outdoor heat exchange device 140 includes a variable flow path 144 for guiding the flow of the refrigerant from the outlet side of the first heat exchange part 141 to the inlet side of the second heat exchange part 142. The variable flow path 144 extends from an outlet pipe of the first heat exchange part 141 to an inlet pipe of the second heat exchange part 142.

The outdoor heat exchanger 140 is provided with a variable valve 145 provided in 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 exchange part 141 may be selectively introduced into the second heat exchange part 142.

In detail, when the variable valve 145 is turned on or opened, the refrigerant that has passed through the first heat exchange part 141 flows into the second heat exchange part 142 through the variable flow path 144. In this case, the first outdoor valve 147a provided to the outlet pipe 147 of the first heat exchange part 141 may be closed.

A second outdoor valve 148a is provided in the outlet pipe 148 of the second heat exchange part 142, and the refrigerant heat-exchanged in the second heat exchange part 142 passes through the opened second outdoor valve 147. Through it may be introduced into the first intermediate heat exchanger (150).

On the other hand, when the variable valve 145 is turned off or closed, the flow of refrigerant to the second heat exchange part 142 is restricted, and the refrigerant passing through the first heat exchange part 141 is the first outdoor valve 147a. ) May be introduced into the first intermediate heat exchanger 150.

Here, the first outdoor valve 147a and the second outdoor valve 148a may be disposed in parallel, corresponding to the arrangement of the first and second heat exchange units 141 and 142.

In the outlet pipe 147 of the first heat exchange part 141 and the outlet pipe 148 of the second heat exchange part 142, a first bypass pipe 149a and a second bypass pipe 149b Is connected.

The first and second bypass pipes 149a and 149b extend from the flow conversion unit 130 to the outlet pipes 147 and 148, and provide the high-pressure refrigerant discharged from the first and second compressors 110 and 112. 1,2 Selectively bypass to the outlet side of the heat exchange part (141,142). In the first and second bypass pipes 149a and 149b, a first bypass valve 149c and a second bypass valve 149d capable of adjusting an opening degree may be installed, respectively.

Intermediate heat exchangers 150 and 170 are disposed at the outlet side of the outdoor heat exchange device 140. The intermediate heat exchangers 150 and 170 include a first intermediate heat exchanger 150 and a second intermediate heat exchanger 150.

When the air conditioner operates for cooling, the refrigerant condensed in the outdoor heat exchange device 140 may flow into the first intermediate heat exchanger 150. On the other hand, when the air conditioner operates for heating, the refrigerant that has passed through the second intermediate heat exchanger 170 may flow into the first intermediate heat exchanger 150.

The first intermediate heat exchanger 150 may be understood as an intermediate heat exchanger in which a first refrigerant circulating through a refrigerant system and some of the refrigerants (second refrigerant) are branched and then exchanged for heat exchange. In addition, the second refrigerant heat-exchanged in the first intermediate heat exchanger 150 may be injected into the first and second compressors 110 and 112, and thus the first intermediate heat exchanger 150 is " It can be called "injection heat exchanger".

The outdoor unit 100 includes a first injection flow path 151 through which the second refrigerant is branched. In addition, a first injection expansion device 153 for depressurizing the second refrigerant is provided in the first injection flow path 151. The first injection expansion device 153 may include an Electric Expansion Valve (EEV).

A plurality of temperature sensors 154 and 155 are provided in the first injection flow path 151. The plurality of temperature sensors (154, 155) include a first temperature sensor (154) for sensing the temperature of the refrigerant before flowing into the first intermediate heat exchanger (150) and a refrigerant after passing through the first intermediate heat exchanger (150). A second temperature sensor 155 for sensing temperature is included.

When the first refrigerant and the second refrigerant are heat-exchanged in the first intermediate heat exchanger 150, the first refrigerant may be supercooled and the second refrigerant may be heated.

Based on the temperature values of the refrigerant detected by the first temperature sensor 154 and the second temperature sensor 155, respectively, the "superheat degree" of the second refrigerant may be recognized. For example, a value obtained by subtracting the temperature value sensed by the first temperature sensor 154 from the temperature value sensed by the second temperature sensor 155 may be recognized as the "superheat degree".

The second refrigerant heat-exchanged in the first intermediate heat exchanger 150 may be injected into the first compressors 110 and 112.

In detail, the first injection flow path 151 may be branched into a first branch flow path 156a and a second branch flow path 156b and connected to the first and second compressors 110 and 112, respectively. It can be understood that the first and second branch channels 156a and 156b are the first injection channels in a broad sense.

The first compressor 110 is provided with a first port 110a, a second port 110b, and a third port 110c as a "suction port" through which a refrigerant is introduced. In addition, the second compressor 112 is provided with a first port 112a, a second port 112b, and a third port 112c as a "suction port" through which the refrigerant is introduced.

Some of the refrigerant in the first injection flow path 151 that has been heat-exchanged in the first intermediate heat exchanger 150 passes through the first injection flow path 151 and the first branch flow path 156a to the first compressor 110 It can be injected into the third port (110c) of. In addition, some of the refrigerant heat-exchanged in the first intermediate heat exchanger 150 passes through the first injection flow path 151 and the second branch flow path 156b, and the third port 112c of the second compressor 112 ) Can be injected.

At this time, the injected refrigerant may have an intermediate pressure, that is, a pressure higher than the suction pressure of the compressor and lower than the discharge pressure. The third ports 110c and 112c may be referred to as “first injection ports”.

The outdoor unit 100 includes a second intermediate heat exchanger 170 connected in series with the first intermediate heat exchanger 150. Based on the cooling operation, the refrigerant (first refrigerant) heat-exchanged in the first intermediate heat exchanger 150 flows into the second intermediate heat exchanger 170. On the other hand, based on the heating operation, the refrigerant heat-exchanged in the second intermediate heat exchanger 170 may flow into the first intermediate heat exchanger 150.

The second intermediate heat exchanger 170 may be understood as an intermediate heat exchanger in which a first refrigerant circulating through a refrigerant system and some of the refrigerants (second refrigerant) are branched and exchanged for heat exchange. In addition, the first refrigerant heat-exchanged in the second intermediate heat exchanger 170 may be supercooled, and accordingly, the second intermediate heat exchanger 170 may be referred to as a "supercooling heat exchanger".

The outdoor unit 100 includes a supercooling passage 171 through which the second refrigerant is branched. In addition, a supercooling expansion device 173 for depressurizing the second refrigerant is provided in the subcooling passage 171. The supercooling expansion device 173 may include an Electric Expansion Valve (EVV).

A plurality of temperature sensors 174 and 175 are provided in the subcooling flow path 171. In the plurality of temperature sensors (174,175), a third temperature sensor (174) sensing the temperature of the refrigerant before flowing into the second intermediate heat exchanger (170) and a refrigerant after passing through the second intermediate heat exchanger (170). A fourth temperature sensor 175 for sensing temperature is included.

In a process in which the first refrigerant and the second refrigerant are heat-exchanged in the subcooling heat exchanger 170, the first refrigerant may be supercooled and the second refrigerant may be heated.

Based on the temperature values of the refrigerant detected by the third temperature sensor 174 and the fourth temperature sensor 175, respectively, the "superheat degree" of the second refrigerant may be recognized. For example, a value obtained by subtracting the temperature value sensed by the third temperature sensor 174 from the temperature value sensed by the fourth temperature sensor 175 may be recognized as the "superheat degree".

The second refrigerant heat-exchanged in the second intermediate heat exchanger 170 may be injected into the first compressors 110 and 112 or bypassed to the gas-liquid separator 160.

In detail, the subcooling passage 171 includes a second injection passage 176 for injecting a refrigerant into the first and second compressors 110 and 112 and a bypass passage 181 for bypassing the refrigerant to the gas-liquid separator 160. ). The second injection flow path 176 and the bypass flow path 180 may be branched at the branch portion 182.

In addition, the second injection flow path 176 may be branched into a third branch flow path 176a and a fourth branch flow path 176b to be connected to the first and second compressors 110 and 112, respectively. The third branch channel (176a) is connected to the second port (110b) of the first compressor (110), the fourth branch channel (176b) is the second port (112b) of the second compressor (112) Can be connected to

Injection valves 177 capable of adjusting the flow rate of the refrigerant may be installed in the third and fourth branch passages 176a and 176b, respectively. The injection valve 177 may include an electronic expansion valve capable of adjusting an opening degree.

Some of the refrigerants in the subcooling flow path 171 heat-exchanged in the second intermediate heat exchanger 170 pass through the second injection flow path 176 and the third branch flow path 176a to the first compressor 110. It can be injected into two ports (110b). In addition, the remaining part of the refrigerant in the subcooling passage 171 heat-exchanged in the second intermediate heat exchanger 150 passes through the second injection passage 176 and the fourth branch passage 176b, and the second compressor 112 ) Can be injected into the second port 112b. At this time, the injected refrigerant may have an intermediate pressure, that is, a pressure higher than the suction pressure of the compressor and lower than the discharge pressure. The second ports 110b and 112b may be referred to as “second injection ports”.

Meanwhile, the gas-liquid separator 160 is configured to separate gaseous refrigerant before the refrigerant flows into the compressors 110 and 112.

The gas-liquid separator 160 is configured integrally with the receiver 162. In detail, the outdoor unit 100 includes a refrigerant storage tank including the gas-liquid separator 160 and a receiver 162 and a partition section that divides an inner space of the refrigerant storage tank. The gas-liquid separator 160 is provided on the upper side of the partition of the internal space of the refrigerant storage tank, and the receiver 162 is provided on the lower side.

The outdoor unit 100 further includes a low pressure pipe 184 extending from the flow conversion unit 130 to the gas-liquid separator 160. The low pressure refrigerant evaporated in the refrigerant cycle may flow into the gas-liquid separator 160 via the flow conversion unit 130 and the low pressure pipe 184.

The bypass flow path 181 is understood as a pipe that guides the refrigerant flowing through the injection flow path 176 to the suction side of the compressors 110 and 112. The bypass flow path 181 is connected to the low pressure pipe 184.

In addition, the gas-liquid separator 160 is provided with a second gas-liquid separation port 160b to which the low pressure pipe 184 is connected. The refrigerant in the bypass flow path 181 may be combined with the refrigerant in the low pressure pipe 184 and may be introduced into the gas-liquid separator 160 through the second gas-liquid separation port 160b.

A bypass valve 183 for selectively blocking the flow of refrigerant is provided in the bypass flow path 181. The amount of the refrigerant flowing into the gas-liquid separator 160 may be adjusted according to the on/off of the bypass valve 183 or the opening degree thereof.

The receiver 162 is understood as a configuration capable of storing at least a portion of the refrigerant circulating through the system.

The outdoor unit 100 further includes a receiver inlet passage 163 connected to the inlet side of the receiver 162. The receiver inlet passage 163 is branched from a pipe connecting the first intermediate heat exchanger 150 and the second intermediate heat exchanger 170 and extends to the receiver 162.

The receiver inlet flow path 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 some of the refrigerants circulating through the system may flow into the receiver 162. In addition, a decompression device is provided in the receiver inlet passage 163 to decompress the refrigerant flowing into the receiver 162.

A receiver outlet pipe 165 is connected to the receiver 162. The receiver outlet pipe 165 may extend to the gas-liquid separator 160. At least some of the refrigerant stored in the receiver 162 may be introduced into the gas-liquid separator 160 through the receiver outlet pipe 165. At the top of the gas-liquid separator 160, a first gas-liquid separation port 160a to which the receiver outlet pipe 165 is connected is provided.

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

The outdoor unit 100 further includes a refrigerant filling pipe 195 extending from a point of the receiver outlet pipe 165. A service valve is installed in the refrigerant charging pipe 195, and when refrigerant is to be replenished in the system, the service valve may be opened to introduce the refrigerant into the refrigerant charging pipe 195. The refrigerant in the refrigerant charging pipe 195 may flow into the gas-liquid separator 160a through the first gas-liquid separation port 160a.

The gas-liquid separator 160 includes a third gas-liquid separation port 160c for discharging the refrigerant stored in the gas-liquid separator 160. The third gas-liquid separation port 160c may be located above the gas-liquid separator 160.

The outdoor unit 100 further includes a suction pipe 169 extending from the third gas-liquid separation port 160c of the gas-liquid separator 160 toward the first and second compressors 110 and 112. The suction pipe 169 may be branched and connected to a first port 110a of the first compressor 110 and a first port 112a of the second compressor 112.

The suction pipe 169 may be provided with a low pressure sensor 169a capable of detecting the pressure of the refrigerant flowing into the first and second compressors 110 and 112, that is, a low pressure of the system.

The outdoor unit 100 further includes an oil return pipe 190 extending from the gas-liquid separator 160 to the suction pipe 169. Oil stored in the gas-liquid separator 160 may flow into the suction pipe 169 through the oil return pipe 190. An oil valve 191 for adjusting the oil flow rate may be installed in the oil return pipe 190.

The outdoor unit 100 further includes an oil supply pipe 119 supplying the oil inside the first and second compressors 110 and 112 to the suction pipe 169. The oil supply pipe 119 extends from the lower portions of the first and second compressors 110 and 112 and is bonded to each other, and is connected to the suction pipe 169.

Meanwhile, the first refrigerant passing through the subcooling heat exchanger 170 may flow into the indoor unit through the liquid pipe 197. In the liquid pipe 197, a liquid pipe temperature sensor 198 for sensing a temperature of a refrigerant flowing through the liquid pipe 197 may be installed.

2 is a flow chart showing a control method of the air conditioner according to the first embodiment of the present invention, and FIG. 3 is a flow chart showing the flow of refrigerant in the normal heating operation of the air conditioner according to the first embodiment of the present invention. FIG. 4 is a system diagram showing a flow of a refrigerant during a low-pressure heating operation of the air conditioner according to the first embodiment of the present invention.

With reference to FIGS. 2 to 4, a control method and a flow of a refrigerant during the heating operation of the air conditioner will be described.

When the heating operation of the air conditioner starts, as shown in FIG. 3, the gaseous refrigerant separated from the gas-liquid separator 160 is sucked into the first and second compressors 110 and 112 through the suction pipe 169. .

The refrigerant compressed by the first and second compressors 110 and 112 flows into the indoor heat exchanger of the indoor unit via the flow conversion unit 130 and the engine 196. The refrigerant condensed in the indoor heat exchanger flows into the outdoor unit 100 through a liquid pipe 197.

Some of the refrigerants (first refrigerant) introduced into the outdoor unit 100 are introduced into the second intermediate heat exchanger 170, and the remaining refrigerant (second refrigerant) is branched into the subcooling flow path 171 and the After being depressurized in the supercooling expansion device 173, heat exchange with the first refrigerant is performed in the second intermediate heat exchanger 170.

The second refrigerant heat-exchanged in the second intermediate heat exchanger 170 flows toward the first intermediate heat exchanger 150. In addition, the second refrigerant heat-exchanged in the second intermediate heat exchanger 170 flows through the second injection flow path 176 in the branch part 182.

The refrigerant in the second injection passage 176 may be branched into the third branch passage 176a and the fourth branch passage 176b to be injected into the first and second compressors 110 and 112.

At this time, the injection valves 177 of the third branch passage 176a and the fourth branch passage 176b are opened, and the refrigerant is the second port 110b of the first compressor 110 and the second compressor It may be injected through the second port 112b of 112.

Meanwhile, the bypass valve 183 is closed. As the bypass valve 183 is closed, the second refrigerant passing through the second intermediate heat exchanger 170 is restricted from flowing into the bypass flow path 181 from the branch part 182.

Part of the refrigerant (main refrigerant) of the first refrigerant that has passed through the second intermediate heat exchanger 170 flows into the first intermediate heat exchanger 150, and the remaining refrigerant (branch refrigerant) is the first injection flow path After being branched to 151 and decompressed in the first injection expansion device 153, heat exchange with the main refrigerant is performed in the first intermediate heat exchanger 150.

The branched refrigerant heat-exchanged in the first intermediate heat exchanger 150 is branched into the first branch passage 156a and the second branch passage 156b, and may be injected into the first and second compressors 110 and 112. In this case, the refrigerant may be injected through the third port 110c of the first compressor 110 and the third port 112c of the second compressor 112 (see FIG. 3 ).

The main refrigerant heat-exchanged in the first intermediate heat exchanger 150 flows into the outdoor heat exchange device 140 and passes through at least one of the first heat exchange unit 141 and the second heat exchange unit 142.

The refrigerant evaporated while passing through the outdoor heat exchange device 140 is introduced into the gas-liquid separator 160 through the flow conversion unit 130, and the first and second compressors 110 and 112 are passed through the suction pipe 169. ) Can be inhaled.

Meanwhile, at least some of the refrigerants flowing from the second intermediate heat exchanger 170 to the first intermediate heat exchanger 150 are introduced into the receiver 162 through the receiver inlet passage 163. Meanwhile, when the receiver outlet valve 166 is opened, the refrigerant stored in the receiver 162 may flow into the gas-liquid separator 160 (S11, S12).

In this way, during the normal heating operation, the pressure of the refrigerant flowing through the suction pipe 169 may be sensed by the low pressure sensor 169a (S13).

It is recognized whether the sensed pressure, that is, the low pressure is less than or equal to the first set pressure. The first set pressure can be understood as a pressure with respect to the lower limit of the low pressure in the normal range. For example, the first set pressure may be 150kpa (S14).

If the sensed pressure is lower than the first set pressure, it is recognized that the low pressure is in an abnormal range, so that a low pressure response heating operation, ie, hot gas control, may be performed.

When the hot gas control is performed, the bypass valve 183 is opened, and the supercooled expansion device 173 is closed. In addition, the injection valves 177 of the first and second compressors 110 and 112 may be opened. For example, among the first and second compressors 110 and 112, the injection valve 177 of the operated compressor may be opened (S15, S16, S17, S18).

By this valve action, the high-pressure refrigerant of the first and second compressors 110 and 112 flows through the third and fourth branch passages 176a and 176b through the opened injection valve 177, and the branch portion 182 ) Flows through the bypass flow path 181. Then, it is introduced into the second gas-liquid separation port 160b of the gas-liquid separator 160 through the opened bypass valve 183 (see FIG. 4 ).

By this hot gas control, a high-pressure refrigerant can be bypassed to the gas-liquid separator 160 side, that is, a low-pressure side, so that an effect of increasing the low pressure can be obtained.

Meanwhile, even in the hot gas control state, injection control of the first and second compressors 110 and 112 through the first injection flow path 151 may be continuously performed. In this way, by continuously injecting the refrigerant passing through the first intermediate heat exchanger 150 into the compressor, the amount of refrigerant circulating in the system can be increased, and the load of the compressor can be reduced by injecting the intermediate pressure refrigerant into the compressor. It works.

In this way, while the low-pressure heating operation is performed, the pressure of the refrigerant flowing through the suction pipe 169 may be continuously sensed by the low-pressure sensor 169a. It may be recognized whether the sensed pressure is greater than or equal to the second set pressure.

The second set pressure is a pressure higher than the first set pressure, and can be understood as a pressure related to a low pressure average value in a normal range. For example, the first set pressure may be 200kpa (S19).

When the sensed pressure exceeds the second set pressure, the low-pressure heating operation is terminated and the normal heating operation is performed unless a heating operation termination command is input. On the other hand, when the sensed pressure is less than the second set pressure, the hot gas control is continuously performed (S20 and S21).

In the above, the case where the air conditioner performs the heating operation has been described, but the same idea may be applied to the case where the air conditioner performs the cooling operation.

In detail, the refrigerant compressed by the compressor is condensed in the outdoor heat exchanger device and then flows into the indoor unit through the first and second heat exchangers, which is different from the heating operation. It should be noted in advance that the event of securing the degree of subcooling and being injected into the compressors 110 and 112 is the same as the heating operation (see FIG. 5).

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

5 is a system diagram showing the configuration of an air conditioner according to a second embodiment of the present invention.

Referring to FIG. 5, in the air conditioner 10 according to the second embodiment of the present invention, injection flow control is installed in the first branch passage 156a and the second branch passage 156b respectively to control the injection flow rate. A portion 157 is further included. For example, the injection flow control unit 157 may include an on-off valve.

Refrigerant injection into the first compressor 110 or the second compressor 112 may be selectively performed according to on or off control of the injection flow controller 157. According to this configuration and operation, there is an advantage in that it is easy to respond to the load because the amount of injection of the refrigerant can be adjusted according to the load of the system.

In Fig. 5, the flow of the refrigerant during the cooling operation is indicated by a solid arrow. Briefly, the refrigerant compressed by the compressors 110 and 112 is introduced into the outdoor heat exchange device 140 through the flow conversion unit 130. The refrigerant introduced into the outdoor heat exchange device 140 passes through at least one of the first heat exchange part 141 and the second heat exchange part 142.

The refrigerant condensed in the outdoor heat exchange device 140 flows into the first intermediate heat exchanger 150. At least a part (second refrigerant) of the main refrigerant (first refrigerant) introduced into the first intermediate heat exchanger 150 is branched and introduced into the first injection flow path 151.

After the second refrigerant flowing through the first injection flow path 151 is expanded, it is exchanged with the first refrigerant in the first intermediate heat exchanger 150. In this process, the first refrigerant is heat radiated to be supercooled, and the second refrigerant is absorbed and injected through the first branch passage 156a and the second branch passage 156b. In this case, whether the refrigerant is injected into which compressor may be determined according to whether the injection flow control unit 157 is turned on or off.

The refrigerant passing through the first intermediate heat exchanger 150 flows into the second intermediate heat exchanger 170, and the refrigerant in the supercooling flow path 171 is the third branch flow path 176a and the fourth branch flow path 176b. It can be injected into the compressor (110, 112) through.

On the other hand, when the bypass valve 183 is opened, at least some of the refrigerants in the subcooling flow path 171 may be branched from the branch portion 182 and introduced into the bypass flow path 181.

The refrigerant that has passed through the second intermediate heat exchanger 170 flows into the indoor unit through a liquid pipe 197, and the refrigerant evaporated from the indoor unit passes through the flow conversion unit 130 to the first and second compressors 110 and 112. Can be reinhaled.

10: outdoor unit 110,112: compressor
125: high pressure sensor 130: flow switching unit
140: outdoor heat exchanger 150: first intermediate heat exchanger
151: first injection flow path 153: first injection expansion device
160: gas-liquid separator 162: receiver
169: suction passage 170: second intermediate heat exchanger
171: supercooling flow path 173: supercooling expansion device
181: bypass flow path 183: bypass valve
182: bypass piping 184: low pressure piping

Claims (15)

A compressor for compressing the refrigerant at high pressure;
A low pressure sensor that senses a low pressure of the refrigerant sucked into the compressor;
A condenser for condensing the refrigerant compressed by the compressor;
An intermediate heat exchanger for heat exchange of the refrigerant condensed in the condenser;
An injection flow path for injecting the refrigerant heat-exchanged in the intermediate heat exchanger to the compressor; And
And a bypass flow path communicating with the injection flow path and guiding the high-pressure gas refrigerant of the compressor to the suction side of the compressor,
The intermediate heat exchanger includes a first intermediate heat exchanger and a second intermediate heat exchanger connected in series with each other,
An air conditioner, characterized in that, based on information sensed by the low pressure sensor, selectively injecting refrigerant into the compressor through the injection flow path or bypass flow of the refrigerant through the bypass flow path. The method of claim 1,
In the bypass flow path,
When the low pressure sensed by the low pressure sensor is less than or equal to the first set pressure, a bypass valve to be opened is installed. The method of claim 2,
In the injection flow path,
When the low pressure sensed by the low pressure sensor is less than or equal to the first set pressure, an injection valve to be opened is installed. The method of claim 3,
When the low pressure sensed by the low pressure sensor is greater than or equal to a second set pressure greater than the first set pressure, the bypass valve is closed and the injection valve is opened. delete The method of claim 1,
In the injection flow path,
A first injection flow path extending from an outlet side of the first intermediate heat exchanger to a first injection port of the compressor to inject a refrigerant; And
An air conditioner including a second injection flow path extending from an outlet side of the second intermediate heat exchanger to a second injection port of the compressor and injecting a refrigerant. The method of claim 1,
An injection expansion device for decompressing the refrigerant flowing into the first intermediate heat exchanger; And
An air conditioner further comprising a subcooling expansion device that depressurizes the refrigerant introduced into the second intermediate heat exchanger and is closed when the low pressure sensed by the low pressure sensor is less than or equal to a first set pressure. The method of claim 6,
A branch portion provided at the outlet side of the second intermediate heat exchanger is further included,
The bypass flow path and the second injection flow path are branched from the branch portion. The method of claim 1,
A gas-liquid separator provided at an inlet side of the compressor and separating a gaseous refrigerant from among refrigerants;
A low pressure pipe guiding the inflow of the refrigerant into the gas-liquid separator; And
An air conditioner further comprising a suction pipe for guiding the gaseous refrigerant separated by the gas-liquid separator to the compressor. The method of claim 9,
The bypass flow path is an air conditioner connected to the low pressure pipe. The method of claim 6,
In the first injection flow path,
An air conditioner, characterized in that an injection flow control unit capable of on/off control is installed. The compressor is driven to perform a normal heating operation;
Sensing a low pressure of the refrigerant sucked into the compressor;
Condensing the refrigerant compressed by the compressor in a condenser;
Heat-exchanging the refrigerant condensed in the condenser in an intermediate heat exchanger; And
If the low pressure of the refrigerant sucked into the compressor is less than or equal to the first set pressure, a heating operation corresponding to the low pressure is performed,
In the step of performing the low pressure response heating operation,
Opening an injection flow path through which the refrigerant heat-exchanged in the intermediate heat exchanger is injected into the compressor; And
Opening a bypass flow path extending from the injection flow path to a suction side of the compressor,
The intermediate heat exchanger includes a first intermediate heat exchanger and a second intermediate heat exchanger connected in series with each other. The method of claim 12,
When the injection flow path is opened, the high-pressure gas refrigerant of the compressor flows to the suction side of the compressor via the injection flow path and the bypass flow path. The method of claim 12,
When the low pressure of the refrigerant is equal to or greater than the second set pressure, the normal heating operation is performed. The method of claim 14,
The second set pressure is higher than the first set pressure.

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