KR101450543B1 - Air conditioning system - Google Patents

Abstract

The air conditioning system according to the present invention can adjust the intermediate pressure more quickly and accurately according to the state of the air conditioner by changing the control mode of the first expansion device for adjusting the intermediate pressure according to the degree of superheat of the refrigerant, Can be improved.

Air conditioning system, phase separator, injection, refrigerant, valve, superheat degree, intermediate pressure

Description

[0001] Air conditioning system [0002]

The present invention relates to an air conditioning system, and more particularly, to an air conditioning system in which the performance and stability of the system can be improved.

Generally, an air conditioning system is a device that compresses, condenses, expands, and evaporates a refrigerant to cool or heat the indoor space.

The air conditioning system is divided into a normal air conditioning system in which one indoor unit is connected to an outdoor unit and a multi air conditioning system in which a plurality of indoor units are connected to an outdoor unit. In addition, the air conditioning system is divided into a cooling system that only operates the refrigerant cycle in one direction to supply only cool air to the room, and a cooling and heating system that can operate the refrigerant cycle in both directions to supply cold or warm air to the room.

The air conditioning system includes a compressor, a condenser, an expansion valve, and an evaporator. The refrigerant discharged from the compressor is condensed in the condenser, and then expanded in the expansion valve. The expanded refrigerant is evaporated in the evaporator, and then sucked into the compressor. During the cooling operation or the heating operation, the refrigerant is injected into the compressor to improve the performance.

However, the air conditioning system according to the related art is very difficult to control, and if the control is not properly performed, the system becomes unstable and damage to the compressor may occur.

An object of the present invention is to provide an air conditioning system in which stability and performance of a system can be improved.

The present invention relates to a refrigerating machine comprising a condenser in which a refrigerant is condensed, a first expansion device in which a refrigerant passed through the condenser is throttled, a second expansion device in which a refrigerant having passed through the first expansion device is throttled, A compressor for introducing a refrigerant branched and injected between the first expansion device and the second expansion device to compress the refrigerant; The control unit controls the first expansion device to the first control mode when the degree of superheat is out of the predetermined range, and if the degree of superheat of the refrigerant is within the predetermined target superheating degree range, 2 < / RTI > control mode.

In the present invention, the compressor includes: a first compression section in which a refrigerant that has passed through the evaporator flows and is compressed; a refrigerant that has passed through the first compression section and branched from the first expansion device and the second expansion device, And a second compression unit in which the refrigerant is introduced and compressed.

In the present invention, the opening change amount of the first expansion device in the second control mode is controlled to be smaller than the opening change amount in the first control mode.

In the present invention, the first control mode senses at least one operating parameter and determines a target opening degree of the first expansion device based on a pre-stored setting value corresponding to the sensed operating parameter value. The first control mode determines a target opening degree of the first expansion device based on a value obtained by linearly combining the set values for the operating parameters.

In the present invention, the second control mode performs fuzzy control on the opening amount of the first expansion device.

In the present invention, the first and second control modes may control the amount of opening of the first expansion device to inject the refrigerant branched from the first expansion device and the second expansion device, So that the pressure reaches a predetermined intermediate pressure.

In the present invention, an injection temperature sensor is disposed in an injection pipe disposed between the first expansion device and the second compression section, and the injection pressure can be grasped based on the temperature measured by the injection temperature sensor.

The air conditioning system according to the present invention can adjust the intermediate pressure more quickly and accurately according to the state of the air conditioner by changing the control mode of the first expansion device for adjusting the intermediate pressure according to the degree of superheat of the refrigerant, Can be improved.

The air conditioning system includes a general air conditioning air conditioner for performing only cooling operation, a heating air conditioner for performing only heating operation, a heat pump type air conditioner for performing both cooling and heating operation, a plurality of indoor spaces for cooling / It includes all multi-type air conditioners. Hereinafter, a heat pump type air conditioner (hereinafter referred to as an " air conditioner ") will be described in detail as an embodiment of an air conditioning system.

Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

FIG. 1 is a configuration diagram of an air conditioner 100 according to an embodiment of the present invention, and FIG. 2 is a block diagram showing a control flow of the air conditioner 100. Referring to FIG.

1 and 2, the air conditioner 100 includes a compressor 110, an indoor heat exchanger 120, an outdoor heat exchanger 130, a first expansion valve 141, a second expansion valve 142 A phase separator 150, and a four-way valve 160. The indoor heat exchanger 120 serves as an evaporator during cooling operation and as a condenser during heating operation. The outdoor heat exchanger 130 acts as a condenser during cooling operation and as an evaporator during heating operation. The compressor (110) compresses the incoming low-temperature low-pressure refrigerant into high-temperature high-pressure refrigerant. The compressor 110 includes a first compression unit 111 and a second compression unit 112. The first compression unit 111 compresses the refrigerant introduced from the evaporator and the second compression unit 112 compresses the refrigerant discharged from the first compression unit 111 and the refrigerant branched from the evaporator and the condenser, The refrigerant is mixed and compressed. However, the present invention is not limited to this, and the compressor 110 may have a multi-stage structure having three or more stages.

The four-way valve 160 guides the refrigerant compressed by the compressor 110 to the outdoor heat exchanger 130 when it is cooled, and the indoor heat exchanger (120). The four-way valve 160 and the compressor 110 are connected to a first connection pipe 171. A compressor outlet temperature sensor 181 and a discharge pressure sensor 182 are disposed in the first connection pipe 171 to measure the discharge temperature and pressure of the refrigerant discharged from the compressor 110. The indoor heat exchanger 120 is disposed in the room and connected to the four-way valve 160 through a second connection pipe 172.

The phase separator 150 separates the refrigerant flowing into the gas-phase refrigerant and the liquid-phase refrigerant, sends the liquid-phase refrigerant to the evaporator, and sends the gaseous refrigerant to the second compression unit 112. The first connection part 151 of the phase separator 150 and the indoor heat exchanger 120 are connected to the third connection pipe 173. The first connection part 151 is a liquid refrigerant discharge pipe during the cooling operation and a refrigerant inflow pipe during the heating operation.

The first expansion valve 141 is disposed on the third connection pipe 173 and is a second expansion device for exchanging the liquid refrigerant introduced from the phase separator 150 during cooling operation. And is a first expansion device for exchanging the liquid refrigerant introduced from the indoor heat exchanger (120).

The outdoor heat exchanger 130 is disposed outdoors and connected to the second connection unit 152 and the fourth connection pipe 174 of the phase separator 150. The second connection portion 152 is a refrigerant inlet pipe during the cooling operation and a liquid refrigerant discharge pipe during the heating operation.

The second expansion valve 142 is disposed on the fourth connection pipe 174 and is a first expansion device for exchanging the liquid refrigerant introduced from the outdoor heat exchanger 130 during cooling operation. Is a second expansion device for exchanging the liquid refrigerant introduced from the phase separator (150).

The outdoor heat exchanger 130 is connected to the four-way valve 160 through a fifth connection pipe 175. In addition, the four-way valve 160 and the inflow pipe of the compressor 110 are connected to the sixth connection pipe 176. A compressor inlet temperature sensor 184 for measuring the temperature of the inlet side of the compressor 110 is disposed on the sixth connection pipe 176.

The second compression unit 112 is connected to the third connection unit 153 of the phase separator 150 through an injection pipe 180. The third connection part 153 is used as a gaseous refrigerant discharge pipe in the cooling and heating operation. An injection valve 143 is disposed on the injection pipe 180. The injection valve 143 controls the amount of refrigerant injected from the phase separator 150 into the second compression unit 112 and the refrigerant pressure. When the injection valve 143 is opened, the gaseous refrigerant in the phase separator 150 flows into the second compression unit 112 through the injection pipe 180. An injection temperature sensor 183 for measuring the temperature of the injected refrigerant is disposed on the injection pipe 180.

The amount of opening of the first and second expansion valves 141 and 142 and the injection valve 143 is controlled by a control unit 200 that controls the operation of the air conditioner.

3 shows the flow of the refrigerant during the heating operation of the air conditioner.

3, the high-temperature, high-pressure gaseous refrigerant discharged from the compressor 110 flows into the indoor heat exchanger 120 via the four-way valve 160. [ The gaseous refrigerant in the indoor heat exchanger (120) undergoes heat exchange with the room air and is condensed. The condensed refrigerant is throttled in the first expansion valve 141, and then flows into the phase separator 160. The liquid refrigerant separated in the phase separator 160 is again throttled by the second expansion valve 142, and then flows into the outdoor heat exchanger 130. In the outdoor heat exchanger (130), the refrigerant evaporates due to heat exchange with the outside air, and the evaporated refrigerant flows into the first compression section (111).

When the operation of gas injection is requested during the heating operation, the control unit 200 opens the injection valve 143. The injection valve 143 is opened and the gaseous refrigerant separated by the phase separator 160 is injected into the second compression unit 112 through the injection pipe 180. [ In the second compression unit 112, the injected refrigerant and the refrigerant from the first compression unit 111 are mixed and then compressed. The refrigerant compressed by the second compression unit 112 is circulated to the four-way valve 160 again.

4 shows the flow of the refrigerant during the cooling operation of the air conditioner.

4, the high-temperature, high-pressure gaseous refrigerant discharged from the compressor 110 flows into the outdoor heat exchanger 130 through the four-way valve 160. In the outdoor heat exchanger (130), the gaseous refrigerant undergoes heat exchange with indoor air and is condensed. The condensed refrigerant is throttled in the second expansion valve 142, and then flows into the phase separator 150. The liquid refrigerant separated in the phase separator 150 is again throttled in the first expansion valve 141 and then flows into the indoor heat exchanger 120. [ In the indoor heat exchanger (120), the refrigerant evaporates due to heat exchange with the outside air, and the evaporated refrigerant flows into the first compression section (111). The control unit 200 shuts the injection valve 143 so that the gaseous refrigerant from the phase separator 150 is not injected into the second compression unit 112. However, the present invention is not limited to this, and the gaseous refrigerant from the phase separator 150 may be injected into the second compression unit 112 even during the cooling operation.

A control method of the air conditioner according to an embodiment of the present invention will now be described.

5 is a flowchart showing a control method in the heating operation of the air conditioner shown in FIG.

When the user drives the air conditioner 100 in order to heat and cool the indoor space, the controller 200 senses a driving command. The control unit 200 initializes the first and second expansion valves 141 and 142 and the injection valve 143. In other words, the control unit 200 controls the first and second expansion valves 141 and 142, 141) 142 are fully opened, and the injection valve 143 is shielded. By blocking the injection valve 143, liquid refrigerant can be prevented from flowing into the compressor 110 at the beginning of the operation.

When the initialization of the first and second expansion valves 141 and 142 and the injection valve 143 is completed, the controller 200 determines that the refrigerant of the air conditioner 100 reaches a predetermined target degree of superheat After the superheat degree is adjusted, the refrigerant reaches a predetermined intermediate pressure.

Here, the superheat degree refers to the temperature difference of the refrigerant between the outlet side of the evaporator and the inlet side of the compressor 110. Generally, a refrigerant does not include a liquid refrigerant after passing through the evaporator, but in the case of a sudden change in load, a liquid refrigerant may be included. In this case, when liquid refrigerant flows into the compressor 110, the compressor 110 is damaged. Accordingly, in order to prevent this, the refrigerant having passed through the evaporator is caused to rise in the process of being transferred to the compressor 110, thereby removing the liquid refrigerant. When the amount of the refrigerant flowing into the evaporator is reduced, evaporation of the refrigerant is completed before completely passing through the evaporator, and the gas refrigerant is continuously heated, thereby increasing the degree of superheat. On the other hand, if the amount of refrigerant is increased, the degree of superheat can be reduced. The degree of superheat is determined by a sensor 185 installed in the indoor heat exchanger 120, a sensor 186 installed in the outdoor heat exchanger 130, a compressor inlet temperature sensor 184 installed at the inlet of the compressor 110, Lt; / RTI >

The intermediate pressure is the pressure in the phase separator 160. By setting the intermediate pressure to a predetermined intermediate pressure, it is possible to reduce the work required in the compressor 110 and to increase the efficiency. By adjusting the amount of refrigerant supplied to the phase separator 160 from the condenser, the intermediate pressure can be adjusted. The intermediate pressure can be measured by the injection temperature sensor 183 provided in the injection pipe 180.

In order to control the degree of superheat, it is necessary to adjust the opening amount of the second expansion device disposed between the phase separator 160 and the evaporator, and to adjust the opening degree of the second expansion device between the condenser and the phase separator 160 And adjusts the opening amount of the deployed first expansion device.

When the air conditioner 100 is in the heating operation mode, the first expansion valve 141 serves as a first expansion device for adjusting the intermediate pressure, and the second expansion valve 142 controls the superheat degree And the second expansion device.

In order to control the degree of superheat, the controller 200 measures the degree of superheat of the refrigerant in real time and controls the amount of opening of the second expansion valve 142 based on the measured superheat of the refrigerant and the error of the superheat degree, (S2) In the controller 200, a fuzzy table is stored based on the overheat measured by the outdoor heat exchanger sensor 186 and the compressor temperature sensor 184, the error of the predetermined target superheat degree and the error variation amount , The opening amount of the second expansion valve 142 is determined from the purge table. The control unit 200 measures the degree of superheat of the refrigerant in real time until the degree of superheat of the refrigerant reaches the target degree of superheat and calculates a degree of opening of the second expansion valve 142 . Therefore, the degree of superheat of the refrigerant can be adjusted more accurately.

Meanwhile, the control unit 200 uses two different control modes to control the intermediate pressure. The control unit 200 compares the superheat degree of the refrigerant with a predetermined target superheat degree range to determine a control mode. (S3) If the target superheat degree range can be set in advance by experiments or the like, Is the range of the superheat degree at which the cycle of < / RTI > The control unit 200 compares the superheat of the refrigerant with the target superheating degree range, determines whether the cycle is stabilized, and determines the control mode. That is, if the superheat degree of the refrigerant is out of the target superheat degree range, the first expansion valve 141 is controlled to the first control mode, and if the superheat degree of the refrigerant is within the predetermined target superheat degree range, The first expansion valve 141 is controlled by switching to the second control mode different from the first control mode.

First, when the degree of superheat of the refrigerant is out of the predetermined target superheat degree range, the controller 200 controls the first expansion valve 141 to the first control mode. (S10) In the first control mode, (S11), and based on the pre-stored set values corresponding to the sensed operating parameter values (S12), the target opening degree of the first expansion valve 141 is set to (S13) In the first control mode, whether or not the gas injection operation in which the refrigerant is injected into the second compression unit 112, the frequency of the compressor 110, the indoor temperature of the air conditioner, (S11), which is a value corresponding to the operating parameter value, is sensed based on the temperature of the compressor 110, the temperature difference, the indoor / outdoor temperature difference, the discharge pressure of the compressor 110 and the discharge temperature of the compressor 110 (S12), the target opening degree of the first expansion valve 141 is set to Determined. (S13) The set values are previously stored jeonghaejyeoseo in the form of a table in the controller 200. The set value for the frequency of the compressor 110 may be set differently depending on whether the gas injection is operated or not. The set values for the operating variable values independently vary the target opening. Since the operating parameters independently vary the target opening degree of the first expansion valve 141, the set values for the respective operating parameters can be easily obtained and the control is easy.

When the target degree of opening of the first expansion valve 141 is determined, the controller 200 changes the amount of opening of the first expansion valve 141 (S14). The opening amount of the first expansion valve 141 is increased or decreased at a time until the opening degree of the first expansion valve 141 reaches the target opening degree (S15). Therefore, the intermediate pressure of the refrigerant can reach the predetermined intermediate pressure more quickly.

On the other hand, if the degree of superheat of the refrigerant is within a predetermined target superheat degree range, the controller 200 determines that the cycle of the air conditioner has entered the stabilization step. Therefore, the controller 200 controls the first expansion valve 141 to the second control mode in order to more accurately adjust the intermediate pressure of the refrigerant to the predetermined intermediate pressure. (S20)

In the second control mode, the operation parameter value is measured, a fuzzy table is stored according to the measured operation variable value, and the opening amount of the first expansion valve 141 is controlled according to the fuzzy table. Here, the operation parameter value is described by taking the pressure of the injection pipe 180 as an example. The opening amount of the first expansion valve 141 is continuously changed until the pressure of the injection pipe 180 reaches a predetermined intermediate pressure. The pressure of the injection pipe 180 can be obtained by measuring the temperature from the injection temperature sensor 183 provided in the injection pipe 180 and converting the measured injection temperature into pressure. ) Stores a fuzzy table based on the injection temperature. The control unit 200 calculates the amount of opening of the first expansion valve 141 based on the purge table S22 and changes the amount of opening of the first expansion valve 141 at S23. , And performs feedback control of the amount of opening of the first expansion valve (141) until the injection pressure reaches the target intermediate pressure (S24).

Therefore, the first control mode is a method of determining the target degree of opening and opening or increasing the amount of opening of the first expansion valve 141 at a time until the target degree of opening is reached, Is a method of gradually changing the amount of opening of the first expansion valve 141 in accordance with the injection temperature or pressure. That is, in the second control mode, the amount of opening of the first expansion valve 141 is controlled more finely than in the first control mode.

Accordingly, when the superheat degree of the refrigerant does not fall within the target superheat degree range, the amount of opening of the first expansion valve 141 is controlled to be larger, and when the superheat degree of the refrigerant is within the target superheat degree range, The opening amount of the first expansion valve 141 is finely adjusted so that the intermediate pressure of the refrigerant can be more accurately adjusted to the predetermined intermediate pressure.

Meanwhile, when the air conditioner is in the cooling operation mode, the second expansion valve 142 functions as a first expansion device for adjusting the intermediate pressure, and the first expansion valve 141 controls the degree of superheat 2 serves as an expansion device. Therefore, in the cooling operation, the second expansion valve 142 is controlled to the first control mode when the superheat degree of the refrigerant is out of the target superheat degree range, and the superheat degree of the refrigerant is controlled to the target superheat degree , The second expansion valve 142 is controlled to the second control mode.

While the present invention has been described with reference to exemplary embodiments, it is to be understood that the invention is not limited to the disclosed exemplary embodiments, but, on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims. Accordingly, the true scope of the present invention should be determined by the technical idea of the appended claims.

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

FIG. 2 is a block diagram showing the control flow of the air conditioner shown in FIG. 1. FIG.

3 is a configuration diagram showing the flow of the refrigerant during the heating operation of the air conditioner shown in Fig.

FIG. 4 is a configuration diagram showing the flow of the refrigerant during the cooling operation of the air conditioner shown in FIG.

Fig. 5 is a flowchart showing a control method when the air conditioner shown in Fig. 1 performs a heating operation.

BRIEF DESCRIPTION OF THE DRAWINGS Fig.

100: air conditioner 110: compressor

120: indoor heat exchanger 130: outdoor heat exchanger

141: first expansion valve 142: second expansion valve

143: Injection valve 150: Phase separator

160: Four-way valve 180: Injection piping

200:

Claims (8)

delete delete delete delete delete delete delete A condenser for condensing the refrigerant; A first expansion device through which the refrigerant passing through the condenser is throttled; A second expansion device in which the refrigerant having passed through the first expansion device is throttled; An evaporator through which the refrigerant having passed through the second expansion device is evaporated; A refrigerant passing through the evaporator and a compressor into which a refrigerant branched and injected between the first expansion device and the second expansion device flows and is compressed; The first expansion device is controlled to the first control mode if the degree of superheat of the refrigerant is out of the predetermined target superheating degree range and if the degree of superheat of the refrigerant is within the predetermined target superheat degree range, And a control unit for switching to a second control mode different from the first control mode, Wherein the compressor includes a first compression section in which a refrigerant passing through the evaporator flows and is compressed, and a refrigerant that is branched and injected between the first expansion device and the second expansion device, And a second compression section that is compressed, Wherein the first and second control modes control the amount of opening of the first expansion device so that the injection pressure of the refrigerant branched between the first expansion device and the second expansion device and injected into the second compression device To reach the pressure, Wherein an injection temperature sensor is disposed in an injection pipe disposed between the first expansion device and the second compression section and the injection pressure is determined based on a temperature measured by the injection temperature sensor.

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