KR100621522B1 - A Device For Controlling The Compressor And Controlling Method Thereof - Google Patents

Abstract

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a compression control apparatus for an air conditioner and a control method thereof, and particularly, to equalize a four-side switching member and a low pressure that are switched in all directions to a refrigerant flow path of an air conditioner having two first and second compressors. Equipped with a solenoid valve for the first and second compressors, for example, 100%, 60%, 40%, etc. to improve the compression capacity in three stages to facilitate variable operation to save energy by drastically reducing power consumption. In addition, the present invention relates to a very useful and effective invention that prevents wear of the first and second compressors by quickly healing the pressure imbalance of the compressor. In addition, under any operating conditions, the liquid back phenomenon that occurs when the compressor starts is significantly reduced, thereby improving the reliability and efficiency of the compressor.

Pressure control device Four-way switching member Solenoid valve Low pressure connector Branch pipe

Description

Pressure control device and control method of air conditioner {A Device For Controlling The Compressor And Controlling Method Thereof}

1 is a configuration diagram of an air conditioner incorporating first and second compressors according to the related art.

2 is a view showing a capacity control method of a general first and second compressors,

3 is a configuration diagram of an air conditioner incorporating first and second compressors according to the present invention;

4 is a flowchart illustrating a state in which both the first and second compressors according to the present invention are operated.

5 is a view of a state in which only the first compressor operating in accordance with the present invention,

6 is a view of a state in which only the second compressor according to the invention operates,

7 is a configuration diagram of a pressure control device of an air conditioner according to the present invention;

8 is an operation flowchart of the start operation control according to the present invention,

9 is an operational flow chart according to the 100% start-up operation control according to the present invention,

10 is an operational flow chart according to the 60% starting operation control according to the present invention,

11 is an operation flowchart of the 40% start-up operation control according to the present invention,

12 is an operation flowchart of a normal operation control process according to the present invention,

13 is a flow chart of operation of the 40% to 60% capacity control according to the present invention,

14 is a flowchart of operation by 60% to 100% capacity control according to the present invention,

15 is a flow chart of operation of the 40% to 100% capacity control according to the present invention,

16 is an operational flow chart according to the 100% to 60% capacity control according to the present invention,

17 is a flowchart of operation by 60% to 40% capacity control according to the present invention,

18 is a flow chart of operation of the 100% to 40% capacity control according to the present invention,

19 is an operational flow diagram according to the stop operation control according to the present invention,

20 is a graph showing a change in capability and power consumption according to various operating conditions according to the present invention.

          * Description of the symbols for the main parts of the drawings *

A: Indoor device B: Outdoor device

102: evaporator 104: first suction tube

106: second suction pipe 108: first accumulator

110: second accumulator 112: first compressor

114: second compressor 116: low pressure connector

116a: branch pipe 118: first discharge pipe

120: second discharge pipe 122: four-way switching member

124: solenoid valve 126: check valve

128 condenser 130 expansion valve

140: control unit 142: signal input unit

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a known air conditioner employing two compressors, and more particularly, to a four-way switching member that is switched in all directions to a refrigerant passage of an air conditioner having two first and second compressors and a solenoid valve for equalizing low pressure. Equipped with the first and second compressors, such as 100%, 60%, 40%, etc., the compression capacity is improved in three stages to facilitate variable operation, which not only saves energy dramatically but also quickly reduces the pressure imbalance of the compressor. The present invention relates to a pressure control device for an air conditioner and a method of controlling the air conditioner to prevent wear of the first and second compressors.

In general, an air conditioner compresses a refrigerant to a high pressure with an outdoor heat exchanger driven by a motor, and liquefies the vaporized refrigerant in an indoor heat exchanger by evaporating the refrigerant condensed at this high pressure into a tube having a small diameter. Therefore, the temperature is lowered to generate cold air, and the cold air generated at this time is discharged to the room to perform cooling.

In addition, the refrigerant vaporized while absorbing heat in the indoor heat exchanger moves from the compressor to the outdoor heat exchanger to condense and liquefy to release heat to the outside to continuously cool through the above process.

1 is a block diagram of a conventional air conditioner incorporating first and second compressors, and FIG.

The conventional air conditioner equipped with the first and second compressors is an outdoor device (B) installed outdoors, and includes first and second compressors 12 and 14 for compressing a refrigerant at high temperature and high pressure. )Wow; First and second discharge pipes (16) (18) for transferring the compressed refrigerant of the first and second compressors (12) and (14); First and second check valves (20) and (22) installed in the first and second discharge pipes (16) and (18) to prevent the refrigerant flowing back; A condenser 24 for condensing the refrigerant conveyed through the first and second check valves 20 and 22 to a low temperature and high pressure state, and rapidly expanding the refrigerant conveyed through the condenser 24 to obtain a low temperature and low pressure. An expansion valve (26) which is an indoor device (A) for making a state, an evaporator (2) having a high temperature and low pressure so as to absorb the heat of the room from the expansion refrigerant by the expansion valve (26), and to discharge cold air; First and second suction pipes (4) and (6) for branching the refrigerant evaporated in (2); and storing excess capacity of the refrigerant branched and moving in the first and second suction pipes (4) and (6). It consists of the 1st, 2nd accumulators (8) and (10).

When the total capacity of the refrigerant is 100%, the first compressor 12 compresses 40% of the total refrigerant capacity, and the second compressor 14 compresses 60% of the total refrigerant capacity.

Looking at the state of using the conventional air conditioner, first, when the user performs a drive that requires 100%, the first and second compressors 12, 14 are driven simultaneously to the first, second The refrigerant sucked into the second suction pipes 4 and 6 is discharged to the first and second discharge pipes 16 and 18 to move.

Then, the first and second check valves 20 and 22 condense in the condenser 24 in a state in which backflow is prevented, and supply the cold air indoors through the expansion valve 26 and the evaporator 2.

On the other hand, when the air conditioner operates a mode for power saving, only one of the first and second compressors 12 and 14 is selectively operated to weakly supply cold air.

As shown in Figure 2, when operating in the automatic operation mode, it is controlled by the difference (DT) of the room temperature and the air conditioning set temperature.

That is, the set temperature difference DT is defined as the room temperature RT-the air conditioner set temperature ST.

If the set temperature difference DT rises above the set value 1 (DTS1), the first and second compressors 12 and 14 are driven to determine the 100% cloud point and the set temperature difference DT is determined. When the value is between the set value 1 and the set value 2 (DTS2), only the second compressor 14 is driven, and the set temperature difference DT is between the set value 2 and the set value 3 (DTS3). Only the first compressor 12 is driven.

Through this control process, the set temperature difference DT is minimized to properly maintain the room temperature RT.

However, the conventional multi-stage air conditioner uses excessive current at the start of the first and second compressors 12 and 14 so that the energy consumption efficiency is remarkably lowered as the compressor starts and stops continuously. I have a problem.

A high pressure is applied between the first and second compressor pipes 16 and 18 between the first and second compressors 12 and 14 and the shank valves 20 and 22. Since the low pressure acts on the suction side first and second suction pipes 4 and 6 of the two compressors 12 and 14, the first and second compressors 12 and 14 stopped in a state where the pressure balance is not maintained. Is activated, there is a significant difficulty in starting the first and second compressors 12 and 14. Therefore, there is a problem in that the compressor cannot be operated immediately because the time required for the equalization for operating the stationary compressor is required.

In addition, the air conditioning system using the plurality of compressors frequently increases and decreases the energy efficiency by repeatedly operating / stopping the compressor. Since the liquid back phenomenon occurs due to the pressure difference during the operation of the compressor, the compressor is frequently used. Due to the operation / stop of the cause of wear of the compressor has a problem of reducing the reliability of the compressor.

SUMMARY OF THE INVENTION The present invention has been made in view of this point, and includes a four-way switching member switched in all directions to a refrigerant passage of an air conditioner having two first and second compressors, and a solenoid valve for equalizing low pressure. The second compressor improves the compression capacity in three stages, such as 100%, 60%, 40%, etc., to facilitate variable operation, thereby dramatically reducing energy, and to quickly heal the pressure imbalance of the compressor. The purpose is to prevent wear of the second compressor.

SUMMARY OF THE INVENTION An object of the present invention is to provide a first and second compressors and continuously change the capacity of the air conditioner, wherein the refrigerant is transferred through the transfer pipe from the evaporator to suck the refrigerant into the first and second compressors. First and second suction pipe for branching; First and second discharge pipes for supplying a refrigerant compressed by the first and second compressors to a condenser; Connected between the first and second discharge pipes and the transfer pipe to communicate the high pressure applied to the discharge side of the first and second compressors with the low pressure formed on the suction side of the first and second compressors to maintain a uniform pressure. It is achieved by providing a pressure control device of an air conditioner consisting of a bypass circuit.

The bypass circuit may include: a low pressure connecting pipe connected between the first discharge pipe and the transfer pipe to equalize the high pressure on the discharge side of the first compressor to a low pressure; A solenoid valve installed in the low pressure connection pipe to control the transfer of refrigerant; A branch pipe connected to the low pressure connecting pipe from the second discharge pipe; It is provided in the second discharge pipe and the branch pipe is made of a four-way switching member for opening and closing the transfer of the refrigerant to equalize the high pressure on the discharge side of the second compressor to low pressure.

In addition, it is preferable to form a control unit for controlling the first and second compressors, the four-way switching member and the solenoid valve, respectively, and to include a signal input unit for inputting a control signal to the control unit.

The four-way switching member is preferably a three-way valve or a four-way valve for opening and closing the second discharge pipe and the branch pipe, respectively.

In addition, another object of the present invention is to provide a first and second compressors, the air conditioner control method having a continuous variable capability, to input the desired operation to the signal input unit to select the operation mode in the control unit Steps; After the operation mode selection step, the first and second compressors are selectively started, and the solenoid valve of the bypass circuit is opened and closed to select whether to connect or disconnect the first discharge pipe and the low pressure connecting pipe or to turn on / off the four-way switching valve. A start operation step of selecting one of the second discharge pipe and the branch pipe to connect or cut off to perform any one of the starting operation among the highest capacity, the intermediate capacity and the lowest capacity operation; Determining whether the safety device is in operation after the start operation step, and if there is an error, enter the stop operation mode; otherwise, terminate the start operation and enter the normal operation mode; After the start operation is terminated and the normal operation mode is entered, the controller determines the load of the first and second compressors based on the difference DT between the room temperature RT and the set temperature ST, and then operates the solenoid valve of the bypass circuit. Select whether to connect or disconnect the first discharge pipe and the low pressure connection pipe by opening or closing, or turn on / off the four-way switching valve to select whether to connect or disconnect the second discharge pipe and the branch pipe. A normal operation step of operating in any one of normal operation modes during load maintenance operation and stop operation; Determining whether the safety device is in operation after the normal operation step, if there is an error, entering the stop operation mode; otherwise, determining whether to operate the safety device continuously or not; After the step of determining whether the safety device is operating or not, the signal input unit receives a stop signal or receives the control unit or detects an abnormality in the safety device and enters the stop operation mode to stop the first and second compressors. It is achieved by providing a pressure control method of an air conditioner consisting of the step of entering the stop operation mode.

In addition, the 100% start-up operation step, which is the highest capacity for starting both the first and second compressors during the start-up operation step, opens the solenoid valve, connects the first discharge pipe and the low pressure connection pipe, and equalizes the pressure to low pressure. Turning on the switching member to connect the second discharge pipe to the branch pipe to equalize it at low pressure; Operating said first compressor after said step; Closing the solenoid valve after the step; After the step, the second compressor is operated, and the four-way switching member is turned off.

And, 60% start-up operation step of the intermediate capacity for starting only the second compressor during the start-up operation step, the ON and the four-way switching member to connect the second discharge pipe to the branch pipe to equalize to low pressure; Connecting the second discharge pipe to the condenser by turning off the four-way switching member after the step; After the step consists of operating only the second compressor.

The 40% start-up operation step, which is the lowest capacity for starting only the first compressor during the start-up operation step, opens the solenoid valve, connects the first discharge pipe and the low pressure connecting pipe to equalize the pressure at low pressure, and turns on the four-way switching member. Connecting the second discharge pipe to the branch pipe to equalize it at low pressure; Operating said first compressor after said step; After the step consists of shutting off the solenoid valve.

The operation of increasing the load from the 40% capacity of the lowest capacity to the 60% capacity of the intermediate capacity among the load increase operation steps of increasing the load in the normal operation step operates the second compressor while the first compressor is in operation. Making a step; Connecting the first discharge pipe to a condenser by turning off the four-way switching member after the step; Stopping the first compressor; After the step, the solenoid valve is operated to connect the first discharge pipe to the low pressure connection pipe to equalize to low pressure, and after a predetermined time, shut off the solenoid valve.

In addition, the operation of increasing the load from the intermediate capacity of 60% to the highest capacity of 100% in the load increasing operation step of increasing the load in the normal operation step operates the solenoid valve while the second compressor is in operation. Connecting the first discharge pipe to the low pressure connecting pipe to equalize the low pressure; Operating the first compressor; After the step consists of shutting off the solenoid valve.

The operation of increasing the load from the 40% capacity of the lowest capacity to the 100% capacity of the highest capacity among the load increasing operation steps of increasing the load in the normal operation step includes: operating the second compressor in a state in which the first compressor operates. Operating; After the step, the four-way switching member is turned off to connect the second discharge pipe to the condenser.

In the normal operation step, the operation of reducing the load from the 100% capacity of the highest capacity to the 60% capacity of the medium capacity of the load reduction operation step reduces the first compressor in a state in which both the first and second compressors are in operation. Stopping; Opening the solenoid valve after the step and connecting the first discharge pipe and the low pressure connection pipe to equalize to low pressure; After the step consists of shutting off the solenoid valve.

In the normal operation step, the operation of reducing the load from the intermediate capacity of 60% to the lowest capacity of 40% capacity is performed by opening the solenoid valve while the second compressor is in operation. Connecting the first discharge pipe and the low pressure connecting pipe to a low pressure; Operating said first compressor after said step; Shutting off the solenoid valve after the step; After the step, the four-way switching member is turned on to connect the second discharge pipe and the branch pipe to the low pressure, and then the step of stopping the second compressor.

In addition, the operation of reducing the load from the 100% capacity of the highest capacity to the 40% capacity of the lowest capacity among the load reduction operation steps of reducing the load in the normal operation step may be performed on all four sides in a state in which both the first and second compressors are in operation. Turning on the member to connect the second discharge pipe and the branch pipe to equalize the pressure at low pressure; After the step consists of stopping the second compressor.

When stopping after the 40% operation, which is the lowest capacity, in the stop operation mode entry step of stopping the first and second compressors, the four-way switching member is first turned off, and then the second discharge pipe is connected to the condenser. It is desirable to stop the compressor.

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

In addition, this embodiment is presented by way of example only, not limitation of the scope of the invention.

3 is a configuration diagram of an air conditioner incorporating first and second compressors according to the present invention, and FIG. 4 is a flowchart of a state in which both the first and second compressors according to the present invention are operated. FIG. 6 is a view illustrating a state in which only the first compressor operates according to the present invention. FIG. 6 is a view illustrating a state in which only the second compressor operates according to the present invention. FIG. 7 is a configuration diagram of a pressure control device for an air conditioner according to the present invention. 8 is a flowchart illustrating the operation by the start operation control according to the present invention.

The configuration of the compression control device of the air conditioner of the present invention is that the first and second compressors 112 and 114 are provided, and the air conditioner having a continuous variable capability is characterized in that the first and second compressors ( First and second suction pipes 104 and 106 for branching the refrigerant transferred from the evaporator 102 through the transfer pipe 103 to suck the refrigerant into the 112 and 114; First and second discharge pipes (118) (120) for supplying the refrigerant compressed by the first and second compressors (104, 106) to the condenser (128); The first and second high pressure pipes connected between the first and second discharge pipes 118 and 120 and the transfer pipe 103 are applied to the discharge side of the first and second compressors 112 and 114. It consists of a bypass circuit (C) which communicates with the low pressure formed on the suction side of the two compressors 112 and 114 to maintain the equal pressure.

And, the bypass circuit (C) is connected between the first discharge pipe 118 and the transfer pipe 103, the low pressure connection pipe for equalizing the high pressure on the discharge side of the first compressor 112 to low pressure ( 116); A solenoid valve 124 installed in the low pressure connecting pipe 116 to control the transfer of the refrigerant; A branch pipe 116a connected to the low pressure connecting pipe 116 from the second discharge pipe 120; It is provided in the second discharge pipe 120 and the branch pipe (116a) is made of a four-way switching member 122 for opening and closing the transfer of the refrigerant to equalize the high pressure on the discharge side of the second compressor 114 to low pressure.

In addition, the controller 140 is configured to control the first and second compressors 112 and 114, the four-way switching member 122, and the solenoid valve 124, respectively, and provides a control signal to the controller 140. It comprises a signal input unit 142 for input.

The four-way switching member 122 uses a three-way valve or a four-way valve that opens and closes the second discharge pipe 120 and the branch pipe 116a, respectively.
On the other hand, reference numerals 108 and 110 are first and second accumulators for storing the surplus capacity of the refrigerant branching and moving in the first and second suction pipes 104 and 106.

Hereinafter, the pressure control method of the air conditioner according to the present invention based on the accompanying drawings.

As shown in FIG. 7 and FIG. 8, the desired operation is input to the signal input unit 142 so that the control unit 142 selects an operation mode (S10).

After the above step, the first and second compressors 112 and 114 are selectively started to perform any one of the starting operation during the highest capacity, the middle capacity, and the lowest capacity operation.

At this time, as shown in Figure 9, during the start operation step (S20), the 100% start operation step (S110) of the highest capacity for starting both the first and second compressors 112, 114, the solenoid Open the valve 124 to connect the first discharge pipe 118 and the low pressure connection pipe 116 to equalize to low pressure. (S111)

Then, the four-way switching member 122 is turned on to connect the second discharge pipe 120 to the branch pipe 116a so as to equalize to a low pressure.

After the step, the first compressor 112 is operated to shut off the solenoid valve 124. (S113) (S114)

Then, after the step, the second compressor 114 is operated to turn off the four-way switching member 122. (S115) (S116)

In addition, as shown in FIG. 10, for example, the 60% starting operation step S120, which is an intermediate capacity for starting only the second compressor 114 during the starting operation step S20, the four-way switching member 122. ON to connect the second discharge pipe 120 to the branch pipe (116a) to equalize to low pressure. (S121)

After the step, the four-way switching member 122 is turned off to connect the second discharge pipe 120 to the condenser 128, and to operate only the second compressor 123. (S122) (S123)

And, as shown in FIG. 11, for example, the lowest capacity for starting only the first compressor 112 during the start operation step (S20), for example, 40% start operation step (S130), the solenoid valve 124 Open and connect the first discharge pipe 118 and the low pressure connection pipe 116 to equalize the low pressure, turn on the four-way switching member 122 to connect the second discharge pipe 120 to the branch pipe (116a) low pressure To equalize. (S131) (S132)

Then, the first compressor 112 is operated, and after the step, the solenoid valve 124 is blocked. (S133) (S134)

And, as shown in Figure 8, after the step (S20), the control unit 140 determines whether the operation of the safety device 150, if there is an error, enters the stop operation mode (S40), otherwise , End the start operation and enter the normal operation mode. (S30) (S50)

On the other hand, as shown in Figure 12, after the step (S50) to control the load of the first and second compressors 112, 114 due to the difference (DT) between the room temperature (RT) and the set temperature (ST) After judging at 140, one of the normal operation modes is selected to operate during load increase operation, load reduction operation, load maintenance operation, and stop operation. (S60)

In this case, as shown in FIG. 13, the operation of increasing the load from the 40% capacity of the lowest capacity to the 60% capacity of the middle capacity among the load increasing operation steps S140 for increasing the load in the normal operation step S70 is performed. The second compressor 114 is operated while the first compressor 112 is in operation (S141).

Then, the four-way switching member 122 is turned off to connect the second discharge pipe 120 to the condenser 128, and to stop the first compressor 112. (S142) (S143)

Then, after the step, the solenoid valve 124 is operated to connect the first discharge pipe 118 to the low pressure connection pipe 116 to equalize to low pressure and to shut off the solenoid valve 124 after a predetermined time. S144) (S145)

As shown in FIG. 14, the operation of increasing the load from the 60% capacity of the medium capacity to the 100% capacity of the maximum capacity during the load increase operation step S140 of increasing the load in the normal operation step S70 is performed by the second operation. The solenoid valve 124 is operated while the compressor 114 is in operation to connect the first discharge pipe 118 to the low pressure connecting pipe 116 to equalize to a low pressure.

Then, the first compressor 112 is operated to shut off the solenoid valve 124. (S147) (S148)

As shown in FIG. 15, the operation of increasing the load from the 40% capacity of the lowest capacity to the 100% capacity of the highest capacity in the load increasing operation step (S140) of increasing the load in the normal operation step (S70) is performed by the first operation. The second compressor 114 is operated while the compressor 112 is in operation, and the four-way switching member 122 is turned off to connect the second discharge pipe 120 to the condenser 128 (S149). (S150)

As shown in FIG. 16, the operation of reducing the load from the 100% capacity of the highest capacity to the 60% capacity of the medium capacity in the load reduction operation step S160 of reducing the load in the normal operation step S70 includes: The first compressor 112 is stopped while both the compressors 112 and 114 are in operation (S161).

Then, the solenoid valve 124 is opened to connect the first discharge pipe 118 and the low pressure connecting pipe 116 to equalize to low pressure, and shut off the solenoid valve 124. (S162) (S163)

As shown in FIG. 17, the operation of reducing the load from the 60% capacity of the medium capacity to the 40% capacity of the lowest capacity in the load reduction operation step S160 of reducing the load in the normal operation step S70 is performed in the second operation. The solenoid valve 124 is opened while the compressor 114 is in operation to connect the first discharge pipe 118 and the low pressure connecting pipe 116 to equalize to low pressure.

Then, the first compressor 112 is operated to block the solenoid valve 124.

Then, the four-way switching member 122 is turned on to connect the second discharge pipe 120 and the branch pipe 116a to be equalized to low pressure, and then the second compressor 114 is stopped. (S167) (S168) )

As shown in FIG. 18, the operation of reducing the load from the 100% capacity of the highest capacity to the 40% capacity of the lowest capacity in the load reduction operation step S160 of reducing the load in the normal operation step S70 may include: In the state in which both of the second compressors 114 are in operation, the four-way switching member 122 is turned on to connect the second discharge pipe 120 and the branch pipe 116a to equalize to a low pressure, and the second compressor 114 (S169) (S170).

And, as shown in Figure 12, after the step is determined whether the operation of the safety device 150, if there is an error, enters the stop operation mode (S40), otherwise, continue the normal operation mode to continue. (S80)

On the other hand, as shown in Figure 19, when the signal input unit 142 receives a stop signal received by the control unit 140 or the abnormality is detected in the safety device 150 enters the stop operation mode (S40) One case is determined by the controller 140 to stop the first and second compressors 112 and 114. (S40) (S90) (S92) (S94)

At this time, in the step (S90) of stopping the first and second compressors 112 and 114, when stopping after the 40% of the lowest capacity, the four-way switching member 122 is first turned off to the second discharge. After the pipe 120 is connected to the condenser 128, the first compressor 112 is stopped.

In the meantime, the capacities of the first and second compressors 112 and 114 are described as 40% and 60%, for example, and the capacity% ratio may be varied as necessary. Do.

20 is a graph showing a change in power and power consumption according to various operating conditions according to the present invention. FIG. 20 shows the power and power consumption of 100%, 60% and 40% of power input. Indicates power and capacity.

Accordingly, as described above, when the compression control apparatus and the control method of the air conditioner according to the present invention are used, the four sides are switched in all directions to the refrigerant flow path of the air conditioner having two first and second compressors. Equipped with a solenoid valve for equalizing the switching member and low pressure, the first and second compressors, for example, 100%, 60%, 40%, etc., improve the compression capacity in three stages, making it easy to operate variablely. It is a very useful and effective invention that prevents wear of the first and second compressors because it not only saves energy by reducing power but also quickly heals the pressure imbalance of the compressor.

In addition, under any operating conditions, the liquid back phenomenon that occurs at the start of the compressor is remarkably reduced, thereby improving the reliability and efficiency of the compressor.

Claims (15)

First and second suction pipes which branch the refrigerant transferred through the transfer pipe from the evaporator to suck the refrigerant into the first and second compressors; First and second discharge pipes for supplying a refrigerant compressed by the first and second compressors to a condenser; It is connected between the first and second discharge pipes and the transfer pipe to communicate the high pressure applied to the discharge side of the first and second compressors to the low pressure formed on the suction side of the first and second compressors to maintain a uniform pressure. A bypass circuit to allow; In the air conditioner having a continuous variable capability consisting of a control unit for controlling the bypass circuit and the first, second compressor, The bypass circuit may include: a low pressure connection pipe connected between the first discharge pipe and the transfer pipe to equalize the high pressure on the discharge side of the first compressor to a low pressure; A solenoid valve installed at the low pressure connection pipe and controlled by a controller to control the transfer of the refrigerant; A branch pipe connected to the low pressure connecting pipe from the second discharge pipe; Air conditioning, characterized in that formed in the position where the second discharge pipe and the branch pipe meets the four sides switching member controlled by the control unit to open and close the transfer of the refrigerant to equalize the high pressure on the discharge side of the second compressor to low pressure Pressure control device. delete The pressure control device of an air conditioner of claim 1, further comprising a signal input unit for inputting a control signal to the control unit. The pressure control device of an air conditioner according to claim 1, wherein the four-way switching member is a three-way valve or a four-way valve that opens and closes the second discharge pipe and the branch pipe, respectively. In the air conditioner control method provided with the first and second compressors to exhibit a continuous variable capacity, Inputting a desired operation to the signal input unit so that the control unit selects an operation mode; After the operation mode selection step, the first and second compressors are selectively started, and the solenoid valve of the bypass circuit is opened and closed to select whether to connect or disconnect the first discharge pipe and the low pressure connecting pipe or to turn on / off the four-way switching valve. A start operation step of selecting one of the second discharge pipe and the branch pipe to connect or cut off to perform any one of the starting operation among the highest capacity, the intermediate capacity and the lowest capacity operation; Determining whether the safety device is in operation after the start operation step, and if there is an error, enter the stop operation mode; otherwise, terminate the start operation and enter the normal operation mode; After the start operation is terminated and the normal operation mode is entered, the controller determines the load of the first and second compressors based on the difference DT between the room temperature RT and the set temperature ST, and then operates the solenoid valve of the bypass circuit. Select whether to connect or disconnect the first discharge pipe and the low pressure connection pipe by opening or closing, or turn on / off the four-way switching valve to select whether to connect or disconnect the second discharge pipe and the branch pipe. A normal operation step of operating in any one of normal operation modes during load maintenance operation and stop operation; Determining whether the safety device is in operation after the normal operation step, if there is an error, entering the stop operation mode; otherwise, determining whether to operate the safety device continuously or not; After the step of determining whether the safety device is operating or not, the signal input unit receives a stop signal or receives the control unit or detects an abnormality in the safety device and enters the stop operation mode to stop the first and second compressors. Pressure control method of the air conditioner, characterized in that the step of entering the stop operation mode. The method of claim 5, wherein the 100% start-up operation step, which is the highest capacity for starting both the first and second compressors during the start-up operation step, the solenoid valve is opened to connect the first discharge pipe and the low pressure connecting pipe to low pressure. Equalizing, turning on the four-way switching member, and connecting the second discharge pipe to the branch pipe to equalize to low pressure; Operating said first compressor after said step; Closing the solenoid valve after the step; Operating the second compressor after the step, and turning off the four-way switching member. The method of claim 5, wherein the 60% start-up operation step, which is an intermediate capacity for starting only the second compressor during the start-up operation step, includes: turning on the four-way switching member to connect the second discharge pipe to the branch pipe to equalize the pressure low pressure; ; Connecting the second discharge pipe to the condenser by turning off the four-way switching member after the step; And after the step, operating only the second compressor. The low-capacity 40% start-up operation step according to claim 5, wherein the solenoid valve is opened to connect the first discharge pipe and the low pressure connection pipe to equalize low pressure in all directions. Turning on the switching member to connect the second discharge pipe to the branch pipe to equalize it at low pressure; Operating said first compressor after said step; And controlling the solenoid valve after the step. The method of claim 5, wherein the operation of increasing the load from the lowest capacity of 40% capacity to the intermediate capacity of 60% capacity in the normal operation step is performed in the state where the first compressor is in operation. Operating the compressor; Connecting the first discharge pipe to a condenser by turning off the four-way switching member after the step; Stopping the first compressor; And operating the solenoid valve after the step to connect the first discharge pipe to the low pressure connection pipe to equalize to low pressure and to shut off the solenoid valve after a certain time. The solenoid of claim 5, wherein the operation of increasing the load from the intermediate capacity of 60% to the highest capacity of 100% in the load increasing operation step of increasing the load in the normal operation step is performed while the second compressor is in operation. Operating a valve to connect the first discharge pipe to the low pressure connection pipe to equalize to low pressure; Operating the first compressor; Pressure control method of the air conditioner, characterized in that the step consisting of closing the solenoid valve after the step. The method of claim 5, wherein the operation of increasing the load from the 40% capacity of the lowest capacity to the 100% capacity of the highest capacity among the load increasing operation steps of increasing the load in the normal operation step is performed in the state where the first compressor is in operation. Operating the compressor; Connecting the second discharge pipe to a condenser by turning off the four-way switching member after the step; pressure control method of an air conditioner. The method of claim 5, wherein the operation of reducing the load from the 100% capacity of the highest capacity to the 60% capacity of the medium capacity among the load reduction operation steps of reducing the load in the normal operation step is performed while both the first and second compressors are in operation. Stopping the first compressor; Opening the solenoid valve after the step and connecting the first discharge pipe and the low pressure connection pipe to equalize to low pressure; Pressure control method of the air conditioner, characterized in that consisting of the step of shutting off the solenoid valve after the step. The solenoid of claim 5, wherein the operation of reducing the load from the intermediate capacity of 60% to the lowest capacity of 40% in the load reduction operation step of reducing the load in the normal operation step is performed while the second compressor is in operation. Opening the valve to connect the first discharge pipe and the low pressure connection pipe to equalize to low pressure; Operating said first compressor after said step; Shutting off the solenoid valve after the step; After the step, the four-way switching member is turned on by connecting the second discharge pipe and the branch pipe to the low pressure, and the step of stopping the second compressor, characterized in that the pressure control method of the air conditioner. 6. The operation of claim 5, wherein the operation of reducing the load from the 100% capacity of the highest capacity to the 40% capacity of the lowest capacity of the load reduction operation steps in which the load is reduced in the normal operation step is in a state in which both the first and second compressors are operating. Turning on the four-way switching member to connect the second discharge pipe and the branch pipe to a low pressure; And a step of stopping the second compressor after the step. The method of claim 5, wherein when stopping after the 40% operation, which is the lowest capacity, in the stop operation mode entry step of stopping the first and second compressors, the four-way switching member is first turned off to connect the second discharge pipe to the condenser. And after that, the first compressor is stopped.

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