KR101450544B1 - Air conditioning system - Google Patents

Abstract

The present invention can improve the performance and stability of the system by changing the control mode of the first and second expansion valves according to the cooling / heating operation mode.

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, in the air conditioning system according to the related art, when the superheat and the intermediate pressure of the refrigerant are not smoothly controlled, the system becomes unstable and the compressor may be damaged.

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 an indoor heat exchanger having an indoor heat exchanger, a first expansion valve in which a refrigerant passed through the indoor heat exchanger is throttled, a second expansion valve in which a refrigerant passing through the first expansion valve is throttled, A compressor for introducing a refrigerant branched and injected between the first expansion valve and the second expansion valve into the first expansion valve and the second expansion valve, And a control unit for controlling the opening amount of the expansion valve to a plurality of control modes, wherein the control unit selects one of the plurality of control modes based on the cooling / heating operation mode.

In the present invention, the compressor may include a first compression unit into which the refrigerant having passed through the outdoor heat exchanger flows and is compressed, a refrigerant passing through the first compression unit, and a second expansion valve branched from the first expansion valve and the second expansion valve And a second compression section in which the injected refrigerant flows together and is compressed.

In the present invention, the control unit may change between a control mode for controlling the opening amount of the first expansion valve and a control mode for controlling the opening amount of the second expansion valve, based on the cooling / heating operation mode.

In the present invention, the control unit controls the amount of opening of the first expansion valve so that the refrigerant branched and injected between the first expansion valve and the second expansion valve reaches a predetermined target intermediate pressure, And the degree of opening of the second expansion valve can be controlled in the superheat degree control mode so that the refrigerant reaches a predetermined target superheat degree.

In the present invention, when the control unit is in the heating operation mode, the amount of opening of the first expansion valve senses an operation variable value of at least one operation variable of the air conditioning system, And the amount of opening of the second expansion valve is controlled in real time by measuring the degree of superheat of the refrigerant in real time, and based on the measured superheat degree until the measured superheat degree reaches a preset superheat degree Can be controlled.

In the present invention, the controller controls the opening degree of the first expansion valve in a superheat degree control mode so that the refrigerant reaches a predetermined target superheating degree, and when the opening degree of the second expansion valve is greater than the opening degree of the second expansion valve, The intermediate pressure control mode can be controlled so that the refrigerant branched and injected between the first expansion valve and the second expansion valve reaches a predetermined target intermediate pressure.

In the present invention, when the control unit is in the cooling operation mode, the amount of opening of the first expansion valve measures the degree of superheat of the refrigerant in real time, and measures the superheated degree of the superheated refrigerant until the measured superheat degree reaches a predetermined superheat degree And the amount of opening of the second expansion valve senses an operating parameter value of at least one operating parameter of the air conditioning system and, based on the pre-stored setting value corresponding to the sensed operating parameter value Can be controlled.

In the present invention, the air conditioning system may further include an injection valve to which the injected refrigerant is throttled, and the control unit may control the injection valve to be opened or closed in response to an injection request of the refrigerant.

According to another aspect of the present invention, there is provided an air conditioner comprising: an indoor heat exchanger; a first expansion valve through which the refrigerant passed through the indoor heat exchanger is throttled; a second expansion valve through which the refrigerant passed through the first expansion valve is throttled; A first expansion valve, a second expansion valve, a first expansion valve, and a second expansion valve, the first expansion valve being connected to the first expansion valve, And a control unit for controlling the amount of opening of the second expansion valve to a plurality of control modes, wherein the control unit sets the amount of opening of the first expansion valve between the first expansion valve and the second expansion valve Pressure control mode so that the refrigerant branched and injected from the first expansion valve reaches a predetermined target intermediate pressure, In the superheating degree control mode, and in the cooling operation mode, the expansion amount of the first expansion valve is controlled to the superheating degree mode, and the opening amount of the second expansion valve is controlled to the intermediate pressure control mode An air conditioning system can be provided. In the present invention, the compressor may include a first compression unit into which the refrigerant having passed through the outdoor heat exchanger flows and is compressed, a refrigerant passing through the first compression unit, and a second expansion valve branched from the first expansion valve and the second expansion valve And a second compression section in which the injected refrigerant flows together and is compressed.

The present invention can improve the performance and stability of the system by changing the control mode of the first and second expansion valves according to the cooling / heating operation mode.

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 introduced 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.

Liquid refrigerant discharge pipe, and is a refrigerant inflow pipe during heating operation.

The first expansion valve 141 is disposed on the third connection pipe 173 and throttles the liquid refrigerant flowing in from the phase separator 150 during the cooling operation and discharges the liquid refrigerant from the indoor heat exchanger 120 during the heating operation. Thereby reducing the liquid refrigerant flowing in.

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 throttles the liquid refrigerant flowing from the outdoor heat exchanger 130 during the cooling operation and discharges the liquid refrigerant from the phase separator 150 And throttles the incoming liquid refrigerant.

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

5 is a flowchart showing a control method of the first and second expansion valves of the air conditioner shown in FIG.

When the user drives the air conditioner 100 to cool or heat 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 step S1. The 1,2 expansion valves 141 and 142 are completely opened and the injection valve 143 is shut off. 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 controls the first expansion valve 141 and the second expansion valve 142 And controls the opening amount in a plurality of control modes.

The plurality of control modes include a superheat degree control mode in which the refrigerant of the air conditioner 100 reaches a predetermined target superheat degree and an intermediate pressure control mode in which the refrigerant reaches a predetermined intermediate pressure.

The controller 200 controls the degree of opening of the valve disposed between the phase separator 160 and the evaporator in the superheat degree control mode in order to control the degree of superheat. In order to adjust the intermediate pressure, the amount of opening of the valve disposed between the condenser and the phase separator 160 is controlled to the intermediate pressure control mode.

The control unit 200 determines whether the air conditioner is in a heating operation mode or a cooling operation mode, and selects one of the plurality of control modes according to the selected operation mode, 2 expansion valve 142, as shown in Fig.

First, when the air conditioner 100 is in the heating operation mode, a control method of the first and second expansion valves 141 and 142 will be described as follows.

When the air conditioner 100 is in the heating operation mode, the controller 200 controls the first expansion valve 141 to the intermediate pressure control mode and the second expansion valve 142 to the superheat degree control Mode. (S3)

In the heating operation mode, since the first expansion valve 141 throttles the refrigerant flowing into the phase separator 160 after being condensed in the indoor heat exchanger 120, the opening of the first expansion valve 141 The pressure in the phase separator 160 can be made to reach a predetermined intermediate pressure by adjusting the amount of metering. Therefore, the controller 200 controls the first expansion valve 141 to the intermediate pressure control mode.

In addition, since the second expansion valve 142 exits the phase separator 160 and throttles the refrigerant flowing into the outdoor heat exchanger 130, the amount of opening of the second expansion valve 142 is adjusted, The degree of superheat of the refrigerant can be controlled. Accordingly, the controller 200 controls the second expansion valve 142 in the superheat degree control mode.

The intermediate pressure control mode is a method of detecting an operation variable value of at least one operation variable and determining a target opening degree of the valve based on a pre-stored set value corresponding to the sensed operation variable value. Therefore, the target degree of opening of the first expansion valve 141 is determined based on the set value. The operating parameters are a plurality of operating parameters. The operating parameters include at least one of the following: whether or not the refrigerant is injected into the second compression unit 112, the gas injection operation, the frequency of the compressor 110, the indoor temperature of the air conditioner 100, The discharge pressure of the compressor 110, the discharge temperature of the compressor 110, and the like. The set values for the operating parameter values of the operating parameters are predetermined and stored 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. A method for obtaining the target opening degree according to the result is as follows.

Target opening degree = F (A1, A2, A3, A4, A5 .....)

Here, A1 to A5 are the operating variable values. The above F (A1, A2, A3, A4, A5 .....) can be expressed by the following equation.

As an example, the target degree of opening may be obtained by multiplying the set values corresponding to the operating variable values, and the following equation can be used.

(A1) * f (A2) * f (A3) * f (A4) * f (A5) *

Here, C is a proportional constant, and f (A1), f (A2), .. are the setting values for A1, A2, ..

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. However, the present invention is not limited to this, and the target degree of opening may be obtained by adding the set values to each other or by other combinations.

The control unit 200 determines the target degree of opening of the first expansion valve 141 and adjusts the opening degree of the first expansion valve 141 at a time until the degree of opening of the first expansion valve 141 reaches the target degree of opening Increase or decrease. Therefore, the intermediate pressure of the refrigerant can reach the predetermined intermediate pressure more quickly.

The second expansion valve 142 is controlled by the superheat degree control mode. The superheat control mode is a method of controlling the degree of superheat of the refrigerant in real time until the superheat degree of the refrigerant reaches the target superheat degree and controlling the amount of opening of the valve based on the measured superheat degree. Accordingly, the opening amount of the second expansion valve 142 is adjusted based on the superheat degree of the refrigerant. The degree of superheat of the refrigerant can be measured by the outdoor heat exchanger sensor 186 installed in the outdoor heat exchanger 130 serving as an evaporator during heating operation and the compressor inlet temperature sensor 184. The control unit 200 stores the fuzzy table based on the measured superheat, the error of the predetermined target superheat degree, and the error change amount, and the opening amount of the second expansion valve 142 is determined from the purge table.

Since the opening amount of the second expansion valve 142 changes based on the degree of superheat measured in real time, the degree of superheat of the refrigerant can be more accurately adjusted according to the operating state.

On the other hand, when the air conditioner is in the cooling operation mode, the control method of the first and second expansion valves 141 and 142 is as follows.

When the air conditioner 100 is in the cooling operation mode, the controller 200 controls the first expansion valve 141 in the superheating degree control mode and the second expansion valve 142 in the intermediate pressure control mode Mode. (S4)

In the cooling operation mode, since the first expansion valve 141 exits the phase separator 160 and throttles the refrigerant flowing into the indoor heat exchanger 120, the opening amount of the first expansion valve 141 The degree of superheat of the refrigerant can be controlled. Therefore, the first expansion valve 141 is controlled in the superheat degree control mode.

Since the second expansion valve 142 throttles the refrigerant flowing into the phase separator 160 after being condensed in the outdoor heat exchanger 130, the amount of opening of the second expansion valve 142 is controlled So that the pressure in the phase separator 160 can reach the predetermined intermediate pressure. Therefore, the second expansion valve 142 is controlled to the intermediate pressure control mode.

Since the controller 200 controls the first expansion valve 141 in the superheat degree control mode, the opening amount of the first expansion valve 141 is changed based on the degree of superheat measured in real time. Therefore, the degree of superheat of the refrigerant can be adjusted more accurately.

In addition, the second expansion valve 142 sets a target degree of opening based on a pre-stored set value corresponding to the sensed operating variable value. The opening amount of the second expansion valve 142 is reduced or increased at a time until the opening degree of the second expansion valve 142 reaches the target opening degree. Therefore, the intermediate pressure of the refrigerant can be adjusted more quickly.

In the present invention, the first expansion valve 141 is controlled to the intermediate pressure control mode when the air conditioner is in the heating operation mode, and is controlled to the superheat degree control mode when the air conditioner is in the cooling operation mode. The second expansion valve 142 is controlled to the superheat degree control mode when the air conditioner is in the heating operation mode and to the intermediate pressure control mode when the air conditioner is in the cooling operation mode. Therefore, since the roles of the first and second expansion valves 141 and 142 are changed based on the cooling / heating operation mode of the air conditioner and the control method is changed accordingly, the performance and stability of the system Can be improved.

If the operation of the gas injection is requested regardless of the cooling / heating operation mode, the control unit 200 opens the injection valve 143 (S6). When the injection valve 143 is opened, The gaseous refrigerant separated by the phase separator 160 is injected into the second compression unit 112 through the injection pipe 180. On the other hand, when there is no request to operate the gas injection, the control unit 200 shuts off the injection valve 143. (S7)

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.

5 is a flowchart showing a control method of the first and second expansion valves of the air conditioner shown in FIG.

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 (10)

delete delete delete delete delete delete delete delete An indoor heat exchanger; A first expansion valve through which the refrigerant having passed through the indoor heat exchanger is throttled; A second expansion valve through which the refrigerant passing through the first expansion valve is throttled; An outdoor heat exchanger in which refrigerant passing through the second expansion valve is heat-exchanged; A refrigerant passing through the outdoor heat exchanger and a compressor through which refrigerant branched and injected between the first expansion valve and the second expansion valve flows and is compressed; And a control unit for controlling the amount of opening of the first expansion valve and the second expansion valve to a plurality of control modes, The control unit controls the amount of opening of the first expansion valve in the intermediate pressure control mode so that the refrigerant branched and injected between the first expansion valve and the second expansion valve reaches a predetermined target intermediate pressure, The degree of opening of the second expansion valve is controlled in a superheat degree control mode so that the refrigerant reaches a predetermined target superheat degree, And the control means controls the opening degree of the first expansion valve to the superheating degree mode and the opening amount of the second expansion valve to the intermediate pressure control mode. The method of claim 9, The refrigerant passing through the first compression section and the refrigerant branched and injected between the first expansion valve and the second expansion valve are connected to each other by the refrigerant passing through the outdoor heat exchanger And a second compression unit that is introduced and compressed.

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