KR101321547B1 - Air conditioning system - Google Patents

Abstract

The air conditioning system according to the present invention compares the pressure of the refrigerant throttled in the first expansion valve with the pressure of the refrigerant injected from the injection heat exchanger to the scroll compressor, thereby controlling the opening degree of the injection valve and preventing failure to the outside. By displaying a warning alert, you can check the conditions under which the inflow is properly performed to ensure reliability and performance.

Air Conditioning, Gas, Injection, Heat Exchangers, Valves, Control

Description

[0001] Air conditioning system [0002]

The present invention relates to an air conditioning system, and more particularly, to an air conditioning system capable of securing performance and reliability of a system by controlling an injection valve according to a pressure at which a refrigerant is injected.

In general, an air conditioning system is a device for cooling or heating an indoor space by performing a process of compressing, condensing, expanding, and evaporating a refrigerant.

The air conditioning system is divided into a general 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 the 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.

However, the air conditioning system according to the prior art may not fully exhibit the cooling and heating ability when the cooling and heating load changes such as the outdoor temperature. For example, in a cold region, there is a problem that the heating performance is very low. When replacing a large-capacity air conditioner or installing a new air conditioner additionally, there is a problem in that the installation cost is high, and the installation space must be secured.

An object of the present invention is to provide an air conditioning system that can ensure the performance and reliability.

An air conditioning system according to the present invention includes a condenser for condensing a refrigerant, a first expansion device for condensing the refrigerant passing through the condenser, a second expansion device for condensing the refrigerant passing through the first expansion device, and the first expansion device. Between an evaporator through which the refrigerant passing through the second expansion device evaporates, a first compression unit through which the refrigerant passing through the evaporator flows in and compressed, a refrigerant passing through the first compression unit, and the first expansion device and the second expansion device; A scroll compressor having a second compression unit into which the refrigerant injected and injected into the reactor is introduced and compressed together; an injection valve branched between the first expansion device and the second expansion device to throttle the refrigerant injected into the second compression unit; A control unit for comparing the pressure of the refrigerant throttled by the first expansion device with the pressure of the refrigerant injected into the second compression unit, and changing the opening degree of the injection valve accordingly. .

In the present invention, the air conditioning system includes an injection pipe that is bypassed between the first expansion device and the second expansion device to guide the refrigerant injected into the second compression unit, and the first expansion device and the second expansion device. The apparatus may further include an injection heat exchanger disposed between the expansion devices to exchange heat between the refrigerant flowing into the second expansion device and the refrigerant passing through the injection pipe.

In the present invention, the injection heat exchanger comprises: a first refrigerant pipe through which one of the refrigerant flowing out of the first expansion device toward the second expansion device and the refrigerant flowing through the injection pipe passes; It may include a second refrigerant pipe formed to surround the refrigerant pipe and the other refrigerant passes through.

In the present invention, the control unit, the pressure difference between the pressure of the evaporator and the pressure difference between the refrigerant condensed in the first expansion device with respect to the pressure difference between the pressure of the evaporator and the pressure of the condenser, The injection pressure ratio of comparing the pressure difference of the injected refrigerant with the pressure difference of the evaporator and the pressure difference of the condenser may be compared, and accordingly, the opening degree of the injection valve may be changed.

In the present invention, if the intermediate pressure ratio is less than the injection pressure ratio, the control unit may close the injection valve.

In the present invention, the control unit may increase the opening degree of the injection valve when the intermediate pressure ratio is greater than the injection pressure ratio and the difference between the intermediate pressure ratio and the injection pressure ratio is within a preset normal operating range.

In the present invention, the control unit may close the injection valve when a difference between the intermediate pressure ratio and the injection pressure ratio is out of a preset normal operating range.

In the present invention, the control unit, if the difference between the intermediate pressure ratio and the injection pressure ratio is out of a predetermined normal operating range, it may display a warning to inform the failure to the outside.

In the present invention, the air conditioning system, a condenser temperature sensor for measuring the temperature of the condenser, a first expansion device temperature sensor for measuring the temperature of the refrigerant from the first expansion device, and the temperature of the injected refrigerant The apparatus further includes an injection temperature sensor measuring a temperature and an evaporator temperature sensor measuring a temperature of the evaporator, and the controller may calculate a temperature measured by the sensors as a pressure using a prestored pressure conversion table.

According to another aspect of the present invention, there is provided a condenser for condensing a refrigerant, a first expansion device for condensing the refrigerant passing through the condenser, a second expansion device for condensing the refrigerant passing through the first expansion device, and the first expansion device. Between an evaporator through which the refrigerant passing through the second expansion device evaporates, a first compression unit through which the refrigerant passing through the evaporator flows in and compressed, a refrigerant passing through the first compression unit, and the first expansion device and the second expansion device; A compressor having a second compression unit which is introduced and compressed together with the refrigerant injected from the injection pipe, an injection pipe that is bypassed between the first expansion device and the second expansion device and guides the refrigerant injected into the second compression unit; And a first refrigerant pipe disposed between the first expansion device and the second expansion device, through which a refrigerant flowing into the second expansion device passes, and a second refrigerant pipe through which the injected refrigerant passes. The injection heat exchanger to be exchanged, an injection valve disposed on the injection pipe to throttle the injected refrigerant, and the injection according to the pressure of the refrigerant throttled by the first expansion device and the pressure of the refrigerant injected into the second compression unit. It may include a control unit for changing the opening degree of the valve.

The air conditioning system according to the present invention compares the pressure of the refrigerant throttled in the first expansion valve with the pressure of the refrigerant injected into the scroll compressor from the injection heat exchanger, and thereby controls the opening degree of the injection valve, thereby injecting You can check the conditions that are being done and control the injection flow rate to ensure performance and stability.

In addition, the pressure of the refrigerant throttled by the first expansion valve and the pressure of the refrigerant injected into the scroll compressor from the injection heat exchanger are compared, and accordingly, the injection of the injection is not performed properly, and a warning indicating an external fault is displayed. By doing so, the reliability can be improved.

In addition, by measuring the saturation temperature without a separate pressure gauge, and by converting the measured saturation temperature into pressure, there is an advantage that the structure is simple and easy to control.

The air conditioning system includes a general home cooling air conditioner that performs only a cooling operation, a heating air conditioner that performs a heating operation only, a heat pump type air conditioner that performs both a heating and cooling operation, and a plurality of indoor spaces. Includes all multi 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 the air conditioner system.

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

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.

1 and 2, the air conditioner 100 includes a scroll compressor 110, an indoor heat exchanger 120, an outdoor heat exchanger 130, a first expansion valve 141, and a second expansion valve ( 142, the injection heat exchanger 150, and the four-way valve 160.

The indoor heat exchanger 120 acts as an evaporator in which the refrigerant is evaporated during the cooling operation, and acts as a condenser in which the refrigerant is condensed during the heating operation.

The outdoor heat exchanger 130 acts as a condenser in which the refrigerant is condensed in the cooling operation, and acts as an evaporator in which the refrigerant is evaporated in the heating operation.

The scroll compressor 110 compresses the low temperature low pressure refrigerant flowing into the high temperature and high pressure. The scroll compressor 110 includes a swing scroll and a fixed scroll having a phase difference of 180 degrees from each other. A compression chamber is formed between the involute wrap of the swinging scroll and the involute wrap of the fixed scroll. As the swing scroll moves, the refrigerant in the compression chamber is gradually compressed and discharged through the discharge port on the center side.

Here, the scroll compressor 110 includes a first compression unit through which the refrigerant passing through the outdoor heat exchanger 130 is introduced and compressed during a heating operation, a refrigerant passing through the first compression unit, and the injection heat exchanger 150. The refrigerant having passed through has a second compression unit which is introduced and compressed together. The first and second compression parts are compression chambers sealed by engagement of the swing scroll and the fixed scroll.

The scroll compressor 110 includes a first inlet 111 connected to a sixth connection pipe 176 to be described later, and a refrigerant injected into the second compression unit connected to the injection pipe 151 to be described later. Inlet 112 is formed.

The four-way valve 160 is a flow path switching valve for switching the flow of the refrigerant during heating and cooling. The four-way valve 160 guides the refrigerant compressed by the scroll compressor 110 to the outdoor heat exchanger 130 when cooled, and guides the indoor heat exchanger 120 when heated.

One side of the four-way valve 160 is connected to the compressor 110 and the first connection pipe 171. The other side of the four-way valve 160 is connected to the indoor heat exchanger 120 and the second connection pipe 172.

The indoor heat exchanger 120 and the injection heat exchanger 150 are connected to a third connection pipe 173, and the first expansion valve 141 is disposed on the third connection pipe 173.

The injection heat exchanger 150 and the evaporator are connected to the fourth connection pipe 174, and the second expansion valve 142 is disposed on the fourth connection pipe 174.

The first expansion valve 141 is a second expansion device for condensing the refrigerant passing through the injection heat exchanger 150 during the cooling operation, and is introduced from the indoor heat exchanger 120 serving as a condenser during the heating operation. A first expansion device for throttling a liquid refrigerant.

The second expansion valve 142 is a first expansion device for throttling liquid refrigerant flowing from the outdoor heat exchanger 130 serving as a condenser during the cooling operation, and passes through the injection heat exchanger 150 during the heating operation. A second expansion device for throttling one refrigerant.

The injection pipe 151 for guiding the refrigerant from the first expansion valve 141 through the injection heat exchanger 150 to the scroll compressor 110 is connected to the third connection pipe 173.

The four-way valve 160 is connected to the outdoor heat exchanger 130 through a fifth connection pipe 175. In addition, the four-way valve 160 is connected to the inlet portion of the scroll compressor 110 and the sixth connecting pipe 176.

The injection heat exchanger 150 heats the refrigerant flowing out of the first expansion valve 141 to the second expansion valve 142 and the refrigerant flowing through the injection pipe 151 during the heating operation.

The injection pipe 151 is provided with an injection valve 153 for controlling the flow rate of the refrigerant to be injected. By controlling the opening degree of the injection valve 153, the amount of refrigerant injected and the refrigerant pressure may be controlled.

In addition, the air conditioner 100 is a condenser temperature sensor for measuring the temperature of the condenser, a first expansion device temperature sensor for measuring the temperature of the refrigerant from the first expansion device, and the temperature of the injected refrigerant Injection temperature sensor for measuring the, and further comprises an evaporator temperature sensor for measuring the temperature of the evaporator.

Since the indoor heat exchanger 120 serves as a condenser during heating operation of the air conditioner 100, the condenser temperature sensor is disposed in the indoor heat exchanger 120 to measure the saturation temperature of the refrigerant. Temperature sensor 180.

During the heating operation of the air conditioner 100, the outdoor heat exchanger 130 acts as an evaporator, so that the evaporator temperature sensor is disposed in the outdoor heat exchanger 130 and measures the saturation temperature of the refrigerant. The temperature sensor 181.

In the heating operation of the air conditioner 100, since the first expansion valve 141 serves as a first expansion device, the first expansion device temperature sensor is disposed on the third connection pipe 173 so that the first expansion valve 141 serves as the first expansion device. The first expansion valve temperature sensor 182 measures the saturation temperature of the refrigerant throttled by the first expansion valve 141.

The injection temperature sensor 183 is disposed on the discharge side of the injection heat exchanger 150 on the injection pipe 151 to measure the saturation temperature of the refrigerant discharged from the injection heat exchanger 150.

3 is a cross-sectional view showing the interior of the injection heat exchanger according to the present invention shown in FIG.

Referring to FIG. 3, the inside of the injection heat exchanger 150 may have a double pipe structure. That is, the injection heat exchanger 150 includes a first refrigerant pipe 154 through which the refrigerant flowing out of the first expansion valve 141 and flowing to the second expansion valve 142 passes and the first refrigerant during the heating operation. A second refrigerant pipe 155 is formed to surround the pipe 154 and the refrigerant flowing through the injection pipe 151 passes therethrough.

The first and second refrigerant pipes 154 and 155 may be formed to be bent in a multiple shape in a loop shape, thereby ensuring a length sufficient for heat exchange even in a narrow space. Meanwhile, the present invention is not limited thereto, and the injection heat exchanger 150 may be made of a plate heat exchanger.

Referring to FIG. 2, the air conditioner 100 may be configured according to the pressure of the refrigerant throttled by the first expansion valve 141 and the pressure of the refrigerant injected into the scroll compressor 110. It further includes a control unit 200 for changing the opening degree.

The controller 200 may know the type of the refrigerant, and know the saturation temperature of a certain point, the pressure conversion table may be stored in advance to calculate the pressure of the point. Accordingly, the control unit 200 measures the saturation temperature measured by the indoor heat exchanger temperature sensor 180, the outdoor heat exchanger temperature sensor 181, the first expansion valve temperature sensor 182, and the injection temperature sensor 183, respectively. Through this, the pressure at each point can be calculated. The controller 200 may control the opening degree of the injection valve 153 according to the calculated pressure. How the control unit 200 controls the opening of the injection valve 153 will be described in more detail later.

4 is a flow diagram of a refrigerant during heating operation of the air conditioner shown in FIG. 1.

Referring to FIG. 4, the high temperature and high pressure refrigerant discharged from the scroll compressor 110 flows into the indoor heat exchanger 120 through the four-way valve 160.

The refrigerant introduced into the indoor heat exchanger 120 condenses by exchanging heat with indoor air. The condensed refrigerant is throttled by the first expansion valve 141.

At this time, when there is a request for operation of gas injection, the control unit 2000 opens the injection valve 153.

When the injection valve 153 is opened, some of the refrigerant flowing through the third connection pipe 173 is bypassed to the injection pipe 151. The refrigerant bypassed from the third connection pipe 173 to the injection pipe 151 is throttled by the injection valve 153.

Since the refrigerant throttled by the injection valve 153 is lowered in temperature and pressure, the refrigerant throttled is relatively lower than the refrigerant flowing into the injection heat exchanger 150 from the third connection pipe 173.

Therefore, in the injection heat exchanger 150, heat exchange between the refrigerant introduced through the injection pipe 151 and the refrigerant introduced through the third connection pipe 173 is performed. The refrigerant flowing through the injection pipe 151 in the injection heat exchanger 150 absorbs heat, and the refrigerant discharged to the second expansion valve 142 is deprived of heat.

The refrigerant deprived of heat from the injection heat exchanger 150 is throttled by the second expansion valve 142 and then flows into the outdoor heat exchanger 130.

The refrigerant introduced into the outdoor heat exchanger 130 is evaporated by heat exchange with external air, and the evaporated refrigerant flows into the first inlet 111 of the scroll compressor 110. The refrigerant introduced into the first inlet 111 is compressed in the first compression unit of the scroll compressor 110.

Meanwhile, the refrigerant absorbing heat in the injection heat exchanger 150 may be a two-phase refrigerant in which at least a portion of the refrigerant is evaporated, mixed with a liquid phase and a gaseous phase, or a refrigerant in a superheated vapor state. The ratio of the liquid refrigerant in the refrigerant absorbing heat in the injection heat exchanger 150 may be adjusted according to the characteristics of the injection heat exchanger 190 or the opening degree of the injection valve 153.

The injection heat exchanger 150 has a double pipe structure composed of the first and second refrigerant pipes 154 and 155, and can inject a two-phase refrigerant or a refrigerant in a superheated vapor state. More injection flow rates can be achieved. The more injection flow rate is secured, the better the heating and cooling performance.

The refrigerant on the injection pipe 151 discharged from the injection heat exchanger 150 flows into the second inlet 112 of the scroll compressor 110. The refrigerant introduced into the second inlet 112 is mixed with the refrigerant compressed in the first compression unit and compressed in the second compression unit.

The refrigerant compressed by the second compression unit is circulated to the four-way valve 160 again.

5 is a flow diagram of a refrigerant during heating operation of the air conditioner shown in FIG. 1.

Referring to FIG. 5, the high temperature and high pressure gaseous refrigerant discharged from the scroll compressor 110 flows into the outdoor heat exchanger 130 via the four-way valve 160.

The gaseous refrigerant flowing into the outdoor heat exchanger 130 is heat-exchanged with the indoor air and condensed. The condensed refrigerant is throttled by the second expansion valve 142 and then passes through the injection heat exchanger 150.

The refrigerant passing through the injection heat exchanger 150 may be throttled by the first expansion valve 141 and then introduced into the indoor heat exchanger 120.

In addition, when the injection valve 153 is opened, some of the refrigerant passing through the injection heat exchanger 150 may be bypassed to the injection valve 153 through the injection pipe 151.

The refrigerant bypassed to the injection pipe 151 is throttled once more by the injection valve 153, so that the temperature and pressure are lower than the refrigerant throttled by the second expansion valve 142. The refrigerant throttled by the injection valve 153 flows into the injection heat exchanger 150.

Therefore, in the injection heat exchanger 150, heat exchange between the refrigerant throttled by the injection valve 153 and the refrigerant throttled by the second expansion valve 142 may be performed.

Since the refrigerant passing through the injection valve 153 is lower than the refrigerant passing through the second expansion valve 142, the refrigerant passing through the injection valve 153 absorbs heat and the second expansion valve The refrigerant passing through 142 is deprived of heat.

Therefore, during the cooling operation, the injection heat exchanger 190 is condensed in the outdoor heat exchanger 130 and serves as a supercooler for supercooling the refrigerant flowing into the indoor heat exchanger 120.

FIG. 6 is a mollie diagram (p-h diagram) illustrating a cycle of an air conditioner according to an embodiment of the present invention, and FIG. 7 is a flowchart illustrating a control method of the air conditioner according to an embodiment of the present invention.

6 and 7, a control method of an air conditioner according to an embodiment of the present invention will be described.

When the user drives the air conditioner 100 to cool the indoor space, the control unit 200 detects a driving command.

When the driving command is detected, the control unit 200 initializes the first and second expansion valves 141 and 142 and the injection valve 153. That is, the controller 200 completely opens the first and second expansion valves 141 and 142, and shields the injection valve 153. By shielding the injection valve 153, it is possible to prevent the liquid refrigerant from flowing into the scroll compressor 110 at an initial stage of driving.

When the initialization of the first and second expansion valves 141 and the injection valve 142 is completed, the control unit 200 determines the opening amounts of the first expansion valve 141 and the second expansion valve 142. To control.

On the other hand, the control unit 200 determines whether there is a gas injection request to the air conditioner 100 during the heating operation (S1).

If there is a gas injection request, the control unit 200 controls the injection valve according to the pressure of the refrigerant from the first expansion valve 141 and the pressure of the refrigerant injected into the second inlet 112 of the scroll compressor 110. The opening degree of 153 is controlled.

The controller calculates a difference (| P19-P45 |) between the pressure P19 of the outdoor heat exchanger 10 serving as an evaporator and the pressure P45 of the indoor heat exchanger 120 serving as a condenser during heating operation. . In addition, the difference (| P19-P6 |) between the pressure P19 of the outdoor heat exchanger 10 and the pressure P6 of the refrigerant throttled by the first expansion valve 141 is obtained. Hereinafter, the pressure P6 of the refrigerant throttled by the first expansion valve 141 is referred to as intermediate pressure.

The controller 200 determines a difference (| P19-P6 |) between the pressure P19 of the outdoor heat exchanger 10 and the pressure P6 of the refrigerant throttled by the first expansion valve 141. Pressure ratio (| P19-P6 | / | P19-P45 |) compared with the difference (| P19-P45 |) of the pressure (P19) of (10) and the pressure (P45) of the said indoor heat exchanger 120, The intermediate pressure ratio).

In addition, the controller 200 may determine a difference (| P19-P11 |) between the pressure P19 of the outdoor heat exchanger 130 and the pressure P11 of the injected refrigerant (hereinafter, referred to as 'injection pressure'). The pressure ratio (| P19-P11 | / | P19-P45 |) compared to the difference (| P19-P45 |) between the pressure (P19) of the outdoor heat exchanger (10) and the pressure (P45) of the indoor heat exchanger (120). , Hereinafter referred to as 'injection pressure ratio').

At this time, the pressure of each point can be converted through the saturation temperature measured at each point. (S2, S3) There are various types of refrigerants, the physical properties of each refrigerant is known to see and know by those skilled in the art. According to this physical property table, knowing the saturation temperature at any point, it can know the pressure accordingly. In the control unit 200 may be stored in advance a physical property table for the refrigerant used. That is, the control unit 200 may store a pressure conversion table for the saturation temperature according to the physical property table. That is, the pressure P19 of the outdoor heat exchanger 130 may be known through the temperature measured by the outdoor heat exchanger temperature sensor 181. In addition, the pressure P45 of the indoor heat exchanger 120 may be known through the temperature measured by the indoor heat exchanger temperature sensor 180.

In addition, the pressure P6 of the refrigerant throttled by the first expansion valve 141 may be known through the temperature measured by the first expansion valve temperature sensor 182. In addition, the pressure P11 of the refrigerant injected through the temperature measured by the injection temperature sensor 183, that is, the injection pressure may be known. (S4)

The controller 200 compares the intermediate pressure ratio (| P19-P6 | / | P19-P45 |) with the injection pressure ratio (| P19-P11 | / | P19-P45 |) (S5).

When the intermediate pressure ratio (| P19-P6 | / | P19-P45 |) is smaller than the injection pressure ratio (| P19-P11 | / | P19-P45 |), the control unit 200 controls the injection valve 153. (S9)

When the intermediate pressure ratio (| P19-P6 | / | P19-P45 |) is smaller than the injection pressure ratio (| P19-P11 | / | P19-P45 |), the injection pipe (151) from the scroll compressor (110) side Reversal may occur such that the refrigerant flows into Therefore, since the control of the injection valve 153 is impossible, it is possible to display a warning indicating a failure to the outside. (S10)

The intermediate pressure ratio (| P19-P6 | / | P19-P45 |) must be greater than the injection pressure ratio (| P19-P11 | / | P19-P45 |) by the pressure difference, so that the scroll from the injection heat exchanger (150) Injection into the compressor 110 is possible.

That is, by comparing the intermediate pressure ratio (| P19-P6 | / | P19-P45 |) with the injection pressure ratio (| P19-P11 | / | P19-P45 |), it is possible to confirm a condition under which injection inflow can be made properly. have.

If the intermediate pressure ratio (| P19-P6 | / | P19-P45 |) is greater than the injection pressure ratio (| P19-P11 | / | P19-P45 |), the control unit 200 of the injection valve 153 Increase the degree of opening; (S6)

The control unit 200 increases the opening degree of the injection valve 153, and the intermediate pressure ratio (| P19-P6 | / | P19-P45 |) and the injection pressure ratio (| P19-P11 | / | P19-P45 It is determined whether the difference of |) is within the normal operating range. (S7)

If the difference between the intermediate pressure ratio (| P19-P6 | / | P19-P45 |) and the injection pressure ratio (| P19-P11 | / | P19-P45 |) is within the normal operating range, the controller 200 The opening degree of the injection valve 153 may be maintained or the opening degree of the injection valve 153 may be changed. The opening degree of the injection valve 153 may be controlled according to the heating unit or other operating variables. (S8)

On the other hand, when the difference between the intermediate pressure ratio (| P19-P6 | / | P19-P45 |) and the injection pressure ratio (| P19-P11 | / | P19-P45 |) is out of a preset normal operating point, the control unit ( 200 shields the injection valve 153 (S9).

When the difference between the intermediate pressure ratio (| P19-P6 | / | P19-P45 |) and the injection pressure ratio (| P19-P11 | / | P19-P45 |) is outside the preset normal operating point, the injection flow rate decreases. Performance is degraded.

Therefore, the injection valve 153 may be shielded to stop the injection and display a warning indicating a failure to the outside (S10).

The air conditioning system according to the present invention compares the pressure of the refrigerant throttled in the first expansion valve with the pressure of the refrigerant injected from the injection heat exchanger to the scroll compressor, thereby controlling the opening degree of the injection valve and preventing failure to the outside. By displaying a warning alert, you can check the conditions under which the inflow is properly performed to ensure reliability and performance.

1 is a configuration diagram of an air conditioner 100 according to an embodiment of the present invention.

2 is a block diagram showing a control flow of the air conditioner 100.

3 is a cross-sectional view showing the interior of the injection heat exchanger according to the present invention shown in FIG.

4 is a view illustrating a flow of a refrigerant during heating operation of the air conditioner illustrated in FIG. 1.

FIG. 5 is a view illustrating a flow of a refrigerant during heating operation of the air conditioner illustrated in FIG. 1.

6 is a mollie diagram (p-h diagram) showing a cycle of the air conditioner according to the embodiment of the present invention.

7 is a flowchart illustrating a control method of an air conditioner according to an embodiment of the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS Fig.

100: air conditioner 110; Scroll compressor

120: indoor heat exchanger 130: outdoor heat exchanger

141: first expansion valve 142: second expansion valve

150: injection heat exchanger 151: injection piping

153: injection valve 200: control unit

Claims (10)

A condenser for condensing the refrigerant; A first expansion device in which the refrigerant passing through the condenser is throttled; A second expansion device in which the refrigerant passing through the first expansion device is throttled; An evaporator through which the refrigerant passing through the second expansion device is evaporated; A first compression unit through which the refrigerant passing through the evaporator is introduced and compressed; A scroll compressor having two compression parts; An injection valve branched between the first expansion device and the second expansion device to throttle the refrigerant injected into the second compression unit; And a controller for comparing the pressure of the refrigerant throttled by the first expansion device with the pressure of the refrigerant injected into the second compression unit, and changing the opening degree of the injection valve accordingly. The control unit, The pressure difference between the pressure of the evaporator and the pressure difference between the refrigerant condensed in the first expansion device is compared with the pressure difference between the pressure of the evaporator and the pressure difference between the condenser, the pressure difference between the pressure of the evaporator and the injected refrigerant. Comparing the injection pressure ratio compared to the pressure difference of the evaporator and the pressure difference of the condenser, and thereby changing the opening degree of the injection valve. The method according to claim 1, The air conditioning system, An injection pipe which is bypassed between the first expansion device and the second expansion device to guide the refrigerant injected into the second compression unit; And an injection heat exchanger disposed between the first expansion device and the second expansion device to heat exchange the refrigerant flowing into the second expansion device and the refrigerant passing through the injection pipe. The method according to claim 2, The injection heat exchanger, A first refrigerant pipe through which one of the refrigerant flowing out of the first expansion device toward the second expansion device and the refrigerant flowing through the injection pipe passes; And a second refrigerant pipe formed to surround the first refrigerant pipe and through which the other refrigerant passes. delete The method according to claim 1, The control unit, And close the injection valve if the intermediate pressure ratio is less than the injection pressure ratio. The method according to claim 1, The control unit, When the intermediate pressure ratio is greater than the injection pressure ratio, and the difference between the intermediate pressure ratio and the injection pressure ratio is within a preset normal operating range, An air conditioning system for increasing the opening of the injection valve. The method according to claim 1, The control unit, And the injection valve is closed when the difference between the intermediate pressure ratio and the injection pressure ratio is outside a preset normal operating range. The method according to claim 1, The control unit, If the difference between the intermediate pressure ratio and the injection pressure ratio is out of a predetermined normal operating range, the air conditioning system for displaying a warning to inform the failure. The method according to claim 1, The air conditioning system, A condenser temperature sensor for measuring the temperature of the condenser, a first expansion device temperature sensor for measuring the temperature of the refrigerant from the first expansion device, an injection temperature sensor for measuring the temperature of the injected refrigerant, and Further comprising an evaporator temperature sensor for measuring the temperature, The control unit calculates the temperature measured by the sensors as a pressure using a pre-stored pressure conversion table. A condenser for condensing the refrigerant; A first expansion device in which the refrigerant passing through the condenser is throttled; A second expansion device in which the refrigerant passing through the first expansion device is throttled; An evaporator through which the refrigerant passing through the second expansion device is evaporated; A first compression unit through which the refrigerant passing through the evaporator flows in and is compressed, a refrigerant passing through the first compression unit, and a refrigerant branched and injected between the first expansion device and the second expansion device are introduced and compressed together A compressor having two compression parts; An injection pipe which is bypassed between the first expansion device and the second expansion device to guide the refrigerant injected into the second compression unit; An injection heat exchanger disposed between the first expansion device and the second expansion device to exchange heat between the first refrigerant pipe through which the refrigerant flowing into the second expansion device passes and the second refrigerant pipe through which the injected refrigerant passes; tile; An injection valve disposed on the injection pipe and configured to throttle the refrigerant to be injected; And a control unit for changing the opening degree of the injection valve according to the pressure of the refrigerant throttled by the first expansion device and the pressure of the refrigerant injected into the second compression unit. The control unit, The pressure difference between the pressure of the evaporator and the pressure difference between the refrigerant condensed in the first expansion device is compared with the pressure difference between the pressure of the evaporator and the pressure difference between the condenser, the pressure difference between the pressure of the evaporator and the injected refrigerant. Comparing the injection pressure ratio compared to the pressure difference of the evaporator and the pressure difference of the condenser, and thereby changing the opening degree of the injection valve.

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