KR101392316B1 - Air conditioning system - Google Patents

Abstract

The air conditioning system according to the present invention controls the frequency of the compressor and changes the control mode of the first and second expansion devices when the discharge temperature of the compressor is out of the normal temperature range, So that the performance and safety of the system can be improved.

Air conditioning system, compressor, emergency, 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, 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 damage to a compressor is prevented, and the stability and performance of the 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, A second compressor for compressing the refrigerant discharged from the compressor, and a second compression unit for compressing the refrigerant to be introduced into the first expansion unit and compressing the refrigerant; and a second control unit for controlling the first expansion unit to the first control mode, Wherein the control unit limits the frequency of the compressor when the discharge temperature of the compressor is out of the normal temperature range and stops the control of the second expansion device, And a third control mode different from the first and second control modes.

In the present invention, the first control mode senses an operation variable value of at least one operation variable, and controls the opening amount based on a pre-stored setting value corresponding to the operation variable value sensed.

In the present invention, the second control mode performs fuzzy control of the opening amount based on the degree of superheat of the refrigerant.

In the present invention, the third control mode increases the opening amount of the first expansion device by the setting opening amount when the discharge temperature of the compressor exceeds the first set temperature. Wherein the controller stops the control of the first expansion device when the opening degree of the first expansion device reaches the maximum opening degree during the execution of the third control mode and stops the control of the second expansion device to the second control mode Can be controlled. And the third control mode may stop the control of the first expansion device when the discharge temperature of the compressor exceeds a third set temperature higher than the first set temperature.

In the present invention, the controller stops the increase of the frequency of the compressor when the discharge temperature of the compressor exceeds the first set temperature, and stops the increase of the discharge temperature of the compressor to the second set temperature higher than the first set temperature If it exceeds, the frequency of the compressor is decreased. The control unit may stop the decrease of the frequency of the compressor when the discharge temperature of the compressor falls below the second set temperature. The controller may turn off the compressor when the discharge temperature of the compressor exceeds a third set temperature higher than the second set temperature. The control unit restarts the compressor when the compressor exceeds the first set time after the compressor is turned off and the discharge temperature of the compressor is less than the first set temperature. And when the compressor is restarted, the first expansion device is fully opened in the third control mode.

In the present invention, when the discharge temperature of the compressor returns to the normal temperature range during the execution of the third control mode, the controller controls the first expansion device to the first control mode, Can be controlled in the second control mode.

In the present invention, the number of times the discharge temperature of the compressor is out of the normal temperature range is stored, and when the stored number exceeds the preset number of times, the control unit stops the operation of the air conditioning system, can do.

The air conditioning system according to the present invention controls the frequency of the compressor and changes the control mode of the first and second expansion devices when the discharge temperature of the compressor is out of the normal temperature range, So that the performance and safety of the system 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 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 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.

When the user drives the air conditioner 100 in order to heat and cool the indoor space, the controller 200 senses a driving command.

When the drive command is sensed, the controller 200 initializes the first and second expansion valves 141 and 142 and the injection valve 143. The controller 200 completely opens the first and second expansion valves 141 and 142 and shields the injection valve 143. [ 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 is completed, the controller 200 controls the amount of opening of the first expansion valve 141 and the second expansion valve 142 And controls them in different control modes from among a plurality of control modes. (S2), the plurality of control modes adjust the amount of opening of the first expansion device for exchanging the refrigerant flowing out of the condenser and flowing into the phase separator (150), so that the refrigerant reaches the predetermined intermediate pressure 1 control mode and an opening amount of the second expansion device for exchanging the refrigerant flowing into the evaporator from the phase separator 150 is controlled so that the refrigerant of the air conditioner 100 is supplied with a predetermined target superheating degree And the second control mode.

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

Referring to FIG. 5, when the initialization is completed (S1), the controller 200 controls the amount of opening of the first and second expansion valves 141 and 142.

When the air conditioner 100 is in the heating operation mode, the first expansion valve 141 functions as the first expansion device, and the second expansion valve 142 functions as the second expansion device . Accordingly, in the heating operation mode, the controller 200 controls the first expansion valve 141 to the first control mode and controls the second expansion valve 142 to the second control mode. (S2)

In the first control mode, a target opening degree of the first expansion valve 141 is determined based on a pre-stored set value corresponding to the sensed operating variable value, do. 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 is set differently depending on whether the gas injection operation is performed or not. That is, the set value for the frequency of the compressor 110 is set differently depending on whether the injection valve 143 is open or closed. The target degree of opening may be obtained by a combination of adding or multiplying the set values.

As described above, when the target degree of opening of the first expansion valve 141 is determined, the controller 200 increases the degree of opening of the first expansion valve 141 at a time so that the degree of opening of the first expansion valve 141 reaches the target degree of opening . Therefore, the intermediate pressure of the refrigerant can reach the predetermined intermediate pressure more quickly.

Also, the controller 200 controls the second expansion valve 142 to the second control mode. In the second control mode, the superheat degree of the refrigerant is measured in real time, and the amount of opening of the second expansion valve 142 is controlled based on the measured superheat degree. The degree of superheat of the refrigerant can be measured by the outdoor heat exchanger sensor 186 installed in the outdoor heat exchanger 130 and the compressor inlet temperature sensor 184. [ The control unit 200 stores a fuzzy table based on the measured superheat, the error of the predetermined target superheat degree, and the error variation amount, and the opening amount of the valve can be determined from the fuzzy table. That is, the controller 200 measures the superheat degree of the refrigerant in real time until the superheat degree of the refrigerant reaches the target superheat degree, and determines the opening amount of the second expansion valve 142 based on the measured superheat degree . Therefore, the degree of superheat of the refrigerant can be adjusted more accurately.

The control unit 200 controls the first expansion valve 141 to the first control mode and controls the second expansion valve 142 to the second control mode, It is checked whether or not the discharge temperature of the refrigerant is out of the normal temperature range. (S3)

If the discharge temperature of the compressor 110 is out of the normal temperature range, the controller 200 can determine that the compressor 110 is in an emergency operating state in which the compressor 110 may be damaged. The discharge temperature of the compressor (110) can be measured by the compressor outlet temperature sensor (181). The normal temperature range is a temperature range in which the compressor 110 is not damaged and a normal cycle can proceed, and can be set in advance according to the model specification. For example, the normal temperature range is set to be less than a preset first set temperature.

When the discharge temperature of the compressor 110 exceeds the first set temperature beyond the normal temperature range, the controller 200 stops the increase of the frequency of the compressor 110. In operation S4,

In addition, the control unit 200 stops the control of the second expansion valve 142 (S5), and controls the first expansion valve 141 to the third control mode different from the first and second control modes . In the third control mode, the opening amount of the first expansion valve (141) is increased by a preset opening amount. (S6)

Thereafter, when the discharge temperature of the compressor 110 continuously rises and exceeds the second set temperature which is higher than the first set temperature, (S7) the frequency of the compressor 110 is reduced by a predetermined set frequency. S8) The frequency of the compressor 110 may be decreased by the predetermined frequency at predetermined intervals. Then, the opening amount of the first expansion valve 141 is continuously increased by the predetermined opening amount (S9)

When the degree of opening of the first expansion valve 141 continues to increase to reach a predetermined maximum degree of opening in the third control mode, the control unit 200 controls the first expansion valve 141 (S11). That is, the controller 200 maintains the opening degree of the first expansion valve 141 and starts the control of the second expansion valve 142. And the second expansion valve 142 is controlled to the second control mode. (S12)

When the opening degree of the first expansion valve (141) is adjusted when the discharge temperature of the compressor (110) is in the emergency operating state out of the normal temperature range, the amount of opening of the second expansion valve It is advantageous to lower the discharge temperature of the compressor (110). Therefore, the opening amount of the first expansion valve 141 is controlled first to adjust the refrigerant amount. Thereafter, when the opening degree of the first expansion valve 141 reaches the maximum opening degree, the opening degree of the second expansion valve 142 is controlled so that the discharge temperature of the compressor 110 is lowered.

Thereafter, when the discharge temperature of the compressor 110 falls and falls below the second set temperature, the compressor stops stopping the frequency of the compressor.

On the other hand, if the discharge temperature of the compressor 110 continuously increases and exceeds the third set temperature which is higher than the first set temperature, the control of the first expansion valve 141 is stopped (S13). , The compressor 110 is turned off (S15), and the compressor 110 is restarted after a first set time.

When the discharge temperature of the compressor 110 exceeds the first set temperature (S17) after the first set time has elapsed (S16), the compressor 110 is kept in the off state and the first set time Is checked again. When the discharge temperature of the compressor 110 is less than the first set temperature after the first predetermined time, the compressor 110 is restarted. (S18) When the compressor 110 is restarted, the first expansion valve 141 can be completely opened (S19) and the first expansion valve 141 can be initialized.

When the discharge temperature of the compressor 110 returns to the normal temperature range, the controller 200 controls the first expansion valve 141 to the first control mode and the second expansion valve 142, Controls the second control mode.

On the other hand, when the number of times the discharge temperature of the compressor 110 exceeds the normal temperature range exceeds a preset number, the controller 200 stops the operation of the air conditioning system 100 and displays a warning to the outside can do. Accordingly, it is possible to prevent damage to components such as the compressor 110 and the like, thereby improving the stability of the system.

In the present invention, the discharge temperature of the compressor 110 is measured in real time to control the frequency of the compressor 110, and the control of the first and second expansion valves 141 and 142 By changing the mode, damage to the compressor 110 can be prevented in advance, and the performance and stability of the system can be improved.

On the other hand, when the air conditioner 100 is in the cooling operation mode, the first expansion valve 141 functions as the second expansion device, and the second expansion valve 142 functions as the second expansion device, The first expansion valve 141 is controlled to the second control mode and the second expansion valve 142 is controlled to the first control mode.

The control unit 200 stops the control of the first expansion valve 141 when the discharge temperature of the compressor 110 is out of the normal temperature range and stops the control of the second expansion valve 142 3 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 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.

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

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 (13)

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; And a control unit for controlling the first expansion device to a first control mode and the second expansion device to a second control mode different from the first control mode, Wherein the control unit limits the frequency of the compressor and stops the control of the second expansion device when the discharge temperature of the compressor is out of the normal temperature range and stops the control of the first expansion device And the third control mode. The method according to claim 1, Wherein the first control mode senses an operation variable value of at least one operation variable and controls an opening amount based on a pre-stored setting value corresponding to the operation variable value sensed. The method according to claim 1, And the second control mode performs fuzzy control on the amount of opening based on the degree of superheat of the refrigerant. The method according to claim 1, And the third control mode increases the opening amount of the first expansion device by the setting opening amount when the discharge temperature of the compressor exceeds the first setting temperature. The method of claim 4, Wherein the controller stops the control of the first expansion device when the opening degree of the first expansion device reaches the maximum opening degree during the execution of the third control mode and stops the control of the second expansion device to the second control mode Controlling air conditioning system. The method of claim 4, And the third control mode stops control of the first expansion device when the discharge temperature of the compressor exceeds a third set temperature higher than the first set temperature. The method according to claim 1, Wherein the controller stops the increase of the frequency of the compressor when the discharge temperature of the compressor exceeds the first set temperature, And decreases the frequency of the compressor when the discharge temperature of the compressor exceeds a second set temperature higher than the first set temperature. The method of claim 7, Wherein the control unit stops the decrease of the frequency of the compressor when the discharge temperature of the compressor falls below the second set temperature. The method of claim 7, Wherein the controller turns off the compressor when the discharge temperature of the compressor exceeds a third set temperature higher than the second set temperature. The method of claim 9, Wherein the controller restarts the compressor when the compressor exceeds the first set time after the compressor is turned off and the discharge temperature of the compressor is below the first set temperature. The method of claim 10, And when the compressor is restarted, fully opens the first expansion device in the third control mode. The method according to claim 1, When the discharge temperature of the compressor returns to the normal temperature range during the execution of the third control mode, Said first expansion device controls said first control mode and said second expansion device controls said second control mode. The method according to claim 1, Wherein the number of times that the discharge temperature of the compressor exceeds the normal temperature range is stored, and when the stored number of times exceeds a predetermined number of times, Wherein the control unit stops the operation of the air conditioning system and displays a warning on the outside.

Images