KR101460717B1 - Air conditioning system - Google Patents

Abstract

The present invention reduces the amount of refrigerant between the first expansion device and the injection valve and regulates the pressure of the injected refrigerant by reducing the opening degree of the first expansion device during the set time when the injection valve is opened, The system can be stabilized.

Air conditioning system, phase separator, injection, refrigerant, valve, opening

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 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 first compression section in which a refrigerant having passed through the evaporator flows and is compressed, a refrigerant having passed through the first compression section, and a second expansion device branched from the first expansion device and the second expansion device, An injection valve that branches off between the first expansion device and the second expansion device and that is injected into the second compression part is throttled; and an injection valve that opens the injection valve, And a control unit for reducing the opening degree of the first expansion device and maintaining the opening degree of the second expansion device before and after the set time period.

In the present invention, the controller may decrease the opening degree of the first expansion device for a predetermined time, and increase the opening degree again if the predetermined time is exceeded.

In the present invention, the controller may store the opening degree of the first expansion device in real time, and may control the opening degree of the first expansion device so that the opening degree of the first expansion device is within a predetermined range of the stored opening degree. Can be controlled.

In the present invention, the control unit may decrease the opening degree of the first expansion device for a preset time period, and if the opening time of the first expansion device exceeds the set time, the opening degree of the first expansion device The opening degree can be increased.

In the present invention, when the opening degree of the injection valve reaches the target opening degree, the control unit senses an operation variable value of at least one operation variable, and based on the previously stored set value corresponding to the sensed operation variable value, So that the amount of opening of the first expansion device can be controlled.

In the present invention, the controller may control the amount of opening of the injection valve such that the amount of opening change of the injection valve changes until the opening degree of the injection valve reaches the target opening degree.

In the present invention, the controller repeats the changing process of changing the opening degree of the injection valve until the opening degree of the injection valve reaches the target opening degree and the holding process of maintaining the opening degree, The opening amount can be controlled.

The present invention reduces the amount of refrigerant between the first expansion device and the injection valve and regulates the pressure of the injected refrigerant by reducing the opening degree of the first expansion device during the opening time of the injection valve, The system can be stabilized.

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 indoor heat exchanger (120) is provided with the indoor heat exchanger sensor (185).

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 outdoor heat exchanger (130) is provided with the outdoor heat exchanger sensor (186). 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.

FIG. 5 is a flowchart showing a control method of the first and second expansion valves and the injection valve in the air conditioner in the heating operation mode 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 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.

The control unit 200 opens the injection valve 143. When the gas injection is requested, the control unit 200 opens the injection valve 143. (S2) Before the injection valve 143 is opened, And stores the opening degree of the expansion valve 141 in real time.

When the air conditioner is in the heating operation mode, the first expansion valve 141 serves as a first expansion device for adjusting the intermediate pressure of the refrigerant.
The opening degree of the first expansion valve 141 is reduced for a set time before and after the opening of the injection valve 143. (S3) When the injection valve 143 is closed and suddenly opened, The discharge pressure of the liquid refrigerant can be increased and the liquid refrigerant can be discharged to the injection pipe 180. If the first expansion valve 141 is partially closed when the injection valve 143 is opened, the amount of the refrigerant in the phase separator 150 is reduced to lower the pressure in the phase separator 150, The liquid refrigerant can be prevented from flowing out to the injection pipe 180.

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When the opening of the injection valve 143 is started, the opening degree of the first expansion valve 141 can be reduced. However, the present invention is not limited to this, and it is also possible to reduce the opening degree of the first expansion valve 141 immediately before opening the injection valve 143.

When the opening degree of the first expansion valve 141 is reduced, the opening degree of the first expansion valve 141 is controlled to fall within a predetermined range of the previously stored opening degree. (S3) As an example, The opening degree of the first expansion valve 141 can be reduced so that the opening degree of the first expansion valve 141 becomes 50% of the stored opening degree. The controller 200 decreases the opening degree of the first expansion valve 141 and then maintains the reduced opening degree.

(S6) When the opening degree of the first expansion valve (141) is increased, the opening degree of the first expansion valve (141) is increased again. The opening degree is increased. After the opening degree of the first expansion valve 141 is increased, the opening degree of the first expansion valve 141 is maintained until the injection valve 143 is fully opened. (S7)

Meanwhile, the control unit 200 stops the control of the second expansion valve 142 before and after opening the injection valve 143, and maintains the opening degree of the second expansion valve 142. Accordingly, when the injection valve 143 is opened, the first expansion valve 141 is partially closed and the opening degree of the second expansion valve 142 is maintained, so that the amount of the refrigerant in the phase separator can be reduced. The discharge pressure in the phase separator can be prevented from rising.

In addition, the control unit 200 may be configured to change the opening degree of the injection valve 143 until the opening degree of the injection valve 143 reaches a predetermined target opening degree, Repeat the maintenance process a plurality of times. That is, the process of changing the opening degree of the injection valve 143 and then maintaining the changed opening degree for a predetermined time is repeated a plurality of times. The opening change amount can be controlled so as to change in accordance with the opening time of the injection valve 143. [ That is, as the opening time of the injection valve 143 increases, the opening change amount can also be controlled to increase. Accordingly, the injection valve 143 is opened little by little at the beginning of the opening of the injection valve 143, so that the discharge pressure of the compressor 110 can be prevented from suddenly rising. Thereafter, the opening degree of the injection valve 143 can be increased so that the opening degree of the injection valve 143 can quickly reach the target opening degree.

When the opening degree of the injection valve 143 reaches the target degree of opening (S8), the controller 200 controls the amount of opening of the first expansion valve to adjust the pressure in the phase separator (S9 ) The control unit 200 senses the operation variable value of at least one operation variable and controls the opening amount of the first expansion valve 141 based on the pre-stored set value corresponding to the sensed operation variable value do.

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 controller 200 obtains the setting values for the operating variable values from the table.

And determines the target degree of opening of the first expansion valve (141) based on the set value. 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.

In addition, the controller 200 senses and stores the current degree of opening of the first expansion valve 141 in real time. When the current opening and the target opening degree are different, the opening degree change amount is determined according to the difference between the current opening degree and the target opening degree. The opening change amount is predetermined according to the difference between the current opening and the target opening degree, and is stored in the form of a table in the controller 200. The opening change amount is obtained from the table. When the opening change amount is determined, the opening degree of the first expansion valve 141 is changed by the opening change amount.

Thereafter, the current degree of opening of the first expansion valve 141 is re-sensed, and the current degree of opening of the first expansion valve 141 is compared with the target degree of opening again. If the current opening and the target opening degree are different, the difference is calculated and the opening change amount is re-determined accordingly. When the opening change amount is re-determined, the opening degree of the first expansion valve 141 is changed by the recrystallized opening change amount.

Thereafter, the above process is repeated until the current degree of opening of the first expansion valve 141 is equal to or less than the target opening degree.

Therefore, when controlling the amount of opening of the first expansion valve 141, the present opening degree of the first expansion valve 141 is taken into consideration, the opening degree of the first expansion valve 141 is gradually increased or gradually decreased Therefore, the system can be more stabilized and the control mode can be easily switched according to the operating state of the air conditioner 100.

Meanwhile, when the air conditioner 100 is in the cooling operation mode, the first expansion valve 141 serves as the second expansion device, and the second expansion valve 142 serves as the first expansion device . Therefore, when the opening of the injection valve 143 is started, the opening degree of the second expansion valve 142 can be decreased for a set time and then increased again. The opening degree of the first expansion valve 141 can be maintained.

In the other embodiment of the present invention, the opening degree of the injection valve 143 is not limited to the predetermined degree of opening when the injection valve 143 is opened, It is possible to reduce the degree of opening of the opening 141. That is, when the opening of the injection valve 143 is started, the opening degree of the first expansion valve 141 is decreased, and then the reduced opening degree is maintained. Thereafter, when the opening degree of the injection valve 143 reaches the preset opening degree, the opening degree of the first expansion valve 141 can be increased again. Here, the predetermined opening degree can be obtained by experimenting with an opening degree in which the system can be stabilized, and can be set to be smaller than the target opening degree for fully opening the injection valve 143. [

Therefore, when the opening degree of the injection valve 143 reaches the predetermined opening degree, the system can be stabilized more quickly by increasing the opening degree of the first expansion valve 141 to the preliminarily stored opening degree.

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 of the first and second expansion valves and the injection valve in the air conditioner in the heating operation mode shown in FIG.

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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)

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 first compression unit into which the refrigerant having passed through the evaporator flows and is compressed; and a refrigerant that has passed through the first compression unit and a refrigerant branched and injected between the first expansion device and the second expansion device, A compressor having a second compression section; An injection valve that branches off between the first expansion device and the second expansion device and throttles the refrigerant injected into the second compression section; And a control unit for decreasing the opening degree of the first expansion device and maintaining the opening degree of the second expansion device for a set time before and after the opening of the injection valve. The method according to claim 1, Wherein the controller reduces the opening degree of the first expansion device for a preset time and increases the opening degree again when the set time is exceeded. The method according to claim 1, Wherein the controller is configured to store the opening degree of the first expansion device in real time and to control the opening degree of the first expansion device to fall within a predetermined range of the stored opening degree when the opening degree of the first expansion device is decreased, . The method of claim 3, Wherein the control unit decreases the opening degree of the first expansion device for a set time and increases the opening degree of the first expansion device so that the opening degree of the first expansion device becomes the stored degree of opening when the setting time is exceeded Air conditioning system. The method according to claim 1, When the opening degree of the injection valve reaches a target opening degree, Sensing an operating parameter value of at least one operating variable and controlling an opening amount of the first expansion device based on a pre-stored setting value corresponding to the sensed operating parameter value. The method according to claim 1, Wherein the control unit controls the amount of opening of the injection valve such that the amount of change of the opening degree of the injection valve changes until the opening degree of the injection valve reaches the target degree of opening. The method according to claim 1, The control unit repeats the changing process of changing the opening degree of the injection valve until the opening degree of the injection valve reaches the target opening degree and the maintaining process of maintaining the opening degree to control the opening amount of the injection valve Air conditioning system. delete

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