KR20150048350A - Air conditioner - Google Patents

Abstract

The present invention relates to an air conditioner. According to an aspect of the present invention, the air conditioner comprises: a compressor compressing refrigerants; a condenser condensing the refrigerant compressed in the compressor; an injection flow path bypassing at least a part of refrigerants among refrigerants discharged from the condenser and injecting the same to the compressor; an injection valve adjusting flow of refrigerants on the injection flow path; an evaporator evaporating refrigerants expanded in an expansion device among refrigerants discharged from the condenser; a bypass pipe connecting the injection flow path and the absorption side of the compressor; a bypass valve controlling flow of the refrigerants in the bypass pipe; and a control unit controlling the injection valve and the bypass valve according to operation load.

Description

Air conditioner

The present specification relates to an air conditioner.

The air conditioner is an appliance for keeping the indoor air in the most suitable condition according to the purpose and purpose. For example, in the summer, the room is controlled by a cool air condition, while in winter the room is controlled by a warm heating condition, by the humidity of the room, and by the clean air of the room.

Korean Patent Laid-Open Publication No. 2013-0100552, which is a prior art document, discloses an air conditioner. The prior art discloses a technique for improving the cooling and heating performance by injecting a refrigerant at an intermediate pressure by a compressor.

However, according to the conventional air conditioner, it is possible to improve the cooling / heating performance by injecting the intermediate-pressure refrigerant into the compressor. However, when the compressor is operated under the minimum load, the compressor operates with a capacity larger than the target capacity, The operation efficiency is reduced, and a problem of unnecessary power consumption occurs.

An object of the present invention is to provide an air conditioner in which power consumption can be reduced by reducing the operating capability of the compressor at the time of minimum load operation.

An air conditioner according to one aspect includes: a compressor for compressing a refrigerant; A condenser for condensing the refrigerant compressed in the compressor; An injection channel for bypassing at least a part of the refrigerant discharged from the condenser and injecting the refrigerant into the compressor; An injection valve for regulating the flow of the refrigerant on the injection path; An evaporator for evaporating the refrigerant expanded in the expansion device among the refrigerants discharged from the condenser; A bypass piping for communicating the injection path with the suction side of the compressor; A bypass valve for regulating the flow of refrigerant in the bypass pipe; And a control unit for controlling the injection valve and the bypass valve in accordance with the operation load.

The control unit opens the injection valve and the bypass valve such that a part of the refrigerant compressed in the compressor is sucked back to the compressor while the air conditioner is operated with a minimum load.

The control unit operates the compressor at a minimum frequency when the air conditioner operates at a minimum load and opens the injection valve and the bypass valve when the capacity of the compressor is greater than the target capacity.

Further comprising an injection expansion unit for expanding the refrigerant flowing into the injection flow passage, wherein the control unit closes the injection expansion unit when the air conditioner is operated with a minimum load.

Further comprising an injection expansion unit for expanding a refrigerant flowing into the injection flow passage, wherein the control unit determines whether injection is to be started, and opens the injection valve and the injection expansion unit when it is determined that injection is necessary, Close the valve.

According to the proposed invention, the pressure of the refrigerant sucked into the compressor is increased, and the amount of refrigerant circulating in the refrigerant cycle is reduced, so that the capacity of the compressor can be reduced.

In addition, since a part of the refrigerant sucked into the compressor is bypassed and then sucked back to the compressor, the compressor does not compress the entire refrigerant sucked, compressing a part of the refrigerant, thereby reducing power consumption of the compressor.

1 is a system diagram showing the configuration of an air conditioner according to an embodiment of the present invention.
2 is a flowchart illustrating a method of controlling an air conditioner according to an embodiment of the present invention.
Fig. 3 is a view showing a refrigerant flow when an intermediate-pressure refrigerant is injected into a compressor; Fig.
4 is a view showing a refrigerant flow when the air conditioner is operated with a minimum load;

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

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

Referring to FIG. 1, an air conditioner 1 according to an embodiment of the present invention includes a refrigeration cycle in which refrigerant circulates. In the air conditioner (1), cooling or heating operation may be performed according to the circulation direction of the refrigerant.

The air conditioner (1) includes a compressor (10) for compressing a refrigerant, a condenser (20) for condensing the refrigerant compressed in the compressor (10), and a condenser A first expansion device 30 and a second expansion device 60 for expanding the refrigerant through the first and second expansion devices 30 and 60 and an evaporator 70 for evaporating the refrigerant through the first and second expansion devices 30 and 60 .

The compressor 10 may be, for example, an inverter compressor. The compressor (10) is capable of multi-stage compression of the refrigerant. That is, the compressor (10) includes a plurality of compression chambers, and the refrigerant compressed in the primary compression chamber is compressed again in the secondary compression chamber.

The outlet pipe of the condenser 20 is provided with a temperature sensor 22 for sensing the refrigerant temperature.

The air conditioner (1) may further include a supercooling device (40) for supercooling the refrigerant passing through the condenser (20). The first expansion device 30 may be, for example, an electronic expansion valve capable of controlling opening degree. Therefore, the refrigerant discharged from the condenser 20 may not expand as it passes through the first expansion device 30.

The air conditioner (1) includes an injection path (80) for bypassing at least a part of the refrigerant in the refrigerant passing through the first expansion device (30) And an injection expansion unit 85 (which may be referred to as an injection flow rate control unit) for controlling the amount of the injection. The refrigerant can expand in the course of passing through the injection expansion part (85).

Among the refrigerants that have passed through the first expansion device 30, the bypassed refrigerant is referred to as "branch refrigerant", and the remaining refrigerant excluding the branch refrigerant is referred to as "main refrigerant". The main refrigerant is substantially a refrigerant discharged from the condenser (20).

In the subcooling device (40), heat exchange is performed between the main refrigerant and the branch refrigerant.

Since the branched refrigerant passes through the injection expansion part 85 and changes to a low temperature and a low pressure, it absorbs heat in the process of heat exchange with the main refrigerant, and the main refrigerant is radiated to the branched refrigerant. Therefore, the main refrigerant can be supercooled. The branch refrigerant that has passed through the supercooling device 40 is introduced (injected) into the compressor 10 through the injection flow path 80.

The injection flow path 80 may include an injection inlet pipe 81 for injecting the refrigerant into the compressor 10 and a temperature sensor 83 for sensing the temperature of the refrigerant on the injection flow path 80. The branched refrigerant of the injection inlet pipe (81) can be introduced into a plurality of compression chambers. For example, when the compressor 10 includes a primary compression chamber and a secondary compression chamber, the branched refrigerant is introduced between the primary compression chamber and the secondary compression chamber. That is, the branched refrigerant may be introduced into the secondary compression chamber in a state mixed with the refrigerant compressed in the primary compression chamber.

The injection valve 80 may be provided with an injection valve 82 for controlling the flow of the refrigerant.

The refrigerant passing through the supercooling device 40 is expanded while passing through the second expansion device 60, and then flows into the evaporator 70.

The outlet pipe of the evaporator 70 may be provided with a pressure sensor 72 for detecting evaporation pressure.

A bypass line 90 may be connected to the injection line 80. The bypass pipe 90 may be connected to a suction pipe of the compressor 10. The bypass pipe 90 may be provided with a bypass valve 92 for controlling the flow of refrigerant.

The injection valve 82 may be positioned between the compressor 10 and a point where the bypass line 90 is connected to the injection line 80.

The control unit, not shown, controls the injection expansion unit 85, the injection valve 82 and the bypass valve 92 in accordance with the load.

In the present invention, the load may be, for example, the target indoor temperature.

FIG. 2 is a flowchart illustrating a control method of an air conditioner according to an embodiment of the present invention. FIG. 3 is a view showing a flow of a refrigerant when an intermediate pressure refrigerant is injected by a compressor, Fig. 3 is a view showing the flow of refrigerant when the air conditioner is operated.

2 to 4, when the air conditioner 1 is turned on, the refrigerant cycle operates (S1). Therefore, the process of compressing, condensing, expanding, and evaporating the refrigerant is repeated.

When the air conditioner 1 is initially operated, the control unit closes the injection expansion unit 85, the injection valve 82 and the bypass valve 92.

During the operation of the air conditioner 1, the controller determines whether a minimum load operation command is input (S2). For example, when a temperature equal to or higher than a reference temperature is input from the target indoor temperature that the user can input during the cooling operation, the controller determines that the cold running load operation command is input. The reference temperature may be the highest temperature among the target indoor temperatures that can be input by the user or a temperature lower than the maximum temperature.

The control unit controls the compressor (10) so that the compressor operates at a minimum frequency when determining that a minimum load operation command is input.

The control unit then determines whether the current capability of the compressor 10 is greater than the target capability. For example, the controller compares the room temperature when the compressor 10 is operated at the minimum frequency with the target room temperature, and if the room temperature is lower than the target room temperature, .

In this case, the controller performs control to reduce the capacity of the compressor. 4, the control unit closes the injection expansion unit 85 and controls the injection valve 82 and the bypass valve 92 to be opened (S4).

Then, refrigerant of the intermediate pressure primarily compressed by the compressor 10 is discharged to the injection flow path, and the refrigerant discharged into the injection flow path 80 flows along the bypass piping 90, Flows into the suction side pipe of the compressor (10). The intermediate pressure refrigerant is finally sucked into the compressor (10).

In this case, the pressure of the refrigerant sucked into the compressor 10 is increased, and the amount of the refrigerant circulating in the refrigerant cycle is reduced, so that the capacity of the compressor can be reduced. In addition, since a part of the refrigerant sucked into the compressor 10 is bypassed and then sucked back to the compressor, the compressor 10 compresses a part of the refrigerant without compressing the whole of the sucked refrigerant There is an advantage that the power consumption of the compressor is reduced.

Of course, when the minimum load operation command is not input, the control unit controls the injection valve and the bypass valve to be closed.

On the other hand, if it is determined in step S2 that the minimum load operation command has not been input, the control unit estimates the refrigerant pressure (hereinafter referred to as "intermediate pressure") in the injection flow path 80 (S5) ).

Specifically, the intermediate pressure is an intermediate pressure assuming that the refrigerant is injected in the course of operation of the present refrigerant cycle. In this embodiment, the intermediate pressure is estimated based on at least the evaporation pressure and the outlet temperature of the condenser . That is, it can be estimated based on the refrigerant state at at least two of the refrigerant cycles.

In this embodiment, the main factors for the intermediate pressure estimation are the evaporation pressure and the outlet temperature of the condenser, and additional supplementary factors may include the compressor suction temperature, the condensation pressure, the compressor suction volume, the compressor rotation speed, and the like. However, in this embodiment, since the main factor has a greater influence on the intermediate-pressure estimation than the co-factor, it is explained that the main factor is used as the minimum factor.

Further, a calculation formula for estimating the intermediate pressure may be stored in a memory (not shown). At this time, the calculation formula may be changed according to the factor for the intermediate pressure estimation, which is determined at the time of manufacturing the product and stored in the memory. When at least the evaporation pressure and the outlet temperature of the condenser are sensed during the operation of the air conditioner, the estimated intermediate pressure is calculated using the above formula.

At this time, the evaporation pressure can be sensed by the pressure sensor 72 provided at the outlet pipe of the evaporator 70, and the outlet temperature of the condenser can be detected by a temperature sensor (not shown) provided at the outlet pipe of the condenser 20 22). ≪ / RTI > At this time, the pressure sensor 72 and the temperature sensor 22 may be collectively referred to as a refrigerant state sensing unit.

Then, the control unit compares the estimated intermediate pressure with the reference pressure to determine whether or not the injection start condition is satisfied. At this time, when the injection start condition is satisfied, the estimated intermediate pressure is lower than the reference pressure.

Since the estimated differential pressure between the intermediate pressure and the high pressure is related to the injection flow rate as described above, if the estimated intermediate pressure is higher than the reference pressure, the injection flow rate can not be ensured and the injection effect is reduced. Therefore, in this embodiment, the injection is started when the estimated intermediate pressure is lower than the reference pressure (S6). That is, the control unit turns on the injection expansion unit 85 so that the refrigerant passes through the injection expansion unit 85.

Then, the intermediate pressure branched refrigerant flows along the injection flow path 80, and then is injected into the compressor 10.

Then, the control unit calculates an injection superheating degree (S7). In this specification, the injection superheat degree means the difference between the saturation temperature corresponding to the estimated intermediate pressure and the temperature of the refrigerant in the injection flow path 80. The temperature of the refrigerant in the injection path 80 can be detected by a temperature sensor 83 provided in the injection path 80. At this time, the saturation temperature corresponding to the pressure of the refrigerant is stored in the memory.

Next, the control unit controls the flow rate of the refrigerant injected based on the calculated injection superheat (S8). At this time, the flow rate of the injected refrigerant can be adjusted by the injection expansion unit 85.

More specifically, the control unit compares the calculated injection superheating degree with a reference superheating degree range, and controls the flow rate to be increased when the calculated injection superheating degree is larger than the maximum value of the reference superheating degree range. If the injection superheating degree is within the reference superheating degree range And controls the flow rate to be decreased when the flow rate is smaller than the minimum value.

For example, when the calculated injection superheating degree is larger than the maximum value, the injection expansion unit 85 is controlled so that the flow amount is increased because the present injection amount is small. On the other hand, when the calculated injection superheating degree is smaller than the minimum value, the injection expansion unit 85 is controlled so that the flow amount is reduced because the present injection amount is large.

According to the proposed invention, the intermediate pressure refrigerant is injected into the compressor, thereby increasing the circulation amount of the refrigerant in the system, thereby improving the cooling and heating performance.

Further, since the refrigerant having a pressure higher than the evaporation pressure is injected and compressed, the compressor power required to compress the same amount of refrigerant is reduced, thereby improving the compression efficiency.

Further, since the state of the refrigerant flowing into the evaporator by the injection of the refrigerant into the compressor is changed, the evaporating ability is improved and the condensing capacity can be improved by increasing the flow rate of the condenser.

Further, there is an advantage that the manufacturing cost of the air conditioner is reduced by estimating the pressure of the injected refrigerant by using the state of the refrigerant in the refrigerant cycle without using the pressure sensor.

10: compressor 20: condenser
40: supercooling device 80:
82: Injection valve 90: Bypass piping
92: Bypass valve

Claims (5)

A compressor for compressing the refrigerant;
A condenser for condensing the refrigerant compressed in the compressor;
An injection channel for bypassing at least a part of the refrigerant discharged from the condenser and injecting the refrigerant into the compressor;
An injection valve for regulating the flow of the refrigerant on the injection path;
An evaporator for evaporating the refrigerant expanded in the expansion device among the refrigerants discharged from the condenser;
A bypass piping for communicating the injection path with the suction side of the compressor;
A bypass valve for regulating the flow of refrigerant in the bypass pipe; And
And a control unit for controlling the injection valve and the bypass valve in accordance with an operation load. The method according to claim 1,
Wherein the control unit opens the injection valve and the bypass valve such that a part of the refrigerant compressed in the compressor is sucked back to the compressor while the air conditioner is operated with a minimum load. 3. The method of claim 2,
Wherein the control unit operates the compressor at a minimum frequency when the air conditioner operates at a minimum load and opens the injection valve and the bypass valve when the capacity of the compressor is greater than a target capacity. The method of claim 3,
Further comprising an injection expansion unit for expanding the refrigerant flowing into the injection flow path,
Wherein the control unit closes the injection expansion unit when the air conditioner is operated with a minimum load. The method according to claim 1,
Further comprising an injection expansion unit for expanding the refrigerant flowing into the injection flow path,
Wherein the control unit determines whether or not the injection is started and opens the injection valve and the injection expanding unit and closes the bypass valve when it is determined that injection is necessary.

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