WO2010071379A2

WO2010071379A2 - Method and apparatus for controlling screw compressor

Info

Publication number: WO2010071379A2
Application number: PCT/KR2009/007585
Authority: WO
Inventors: 이재윤
Original assignee: 주식회사 건영기계
Priority date: 2008-12-18
Filing date: 2009-12-18
Publication date: 2010-06-24
Also published as: WO2010071379A4; KR100908022B1; WO2010071379A3

Abstract

Disclosed are a method and apparatus for controlling and enabling a screw compressor to adapt to work environment, work characteristics or other conditions in a field, maximize electric energy savings and improve the performance of the screw compressor. The apparatus for controlling a screw compressor of the present invention comprises: a screw compressor that includes a suction valve being opened or closed by operations of a solenoid valve to suck in or block outside air, a motor run on an applied power to generate a torque of a predetermined rotational speed, a compressor compressing and then discharging the air having been sucked in through the suction valve under the influence of the motor torque, an oil separator separating and then discharging oil contained in the compressed air from the compressor, and an air feed line used for delivering air to the suction valve, motor, compressor and oil separator to which the line is piped, respectively; a control box that includes a pressure switch being switched according to a pressure detected by one or more pressure sensors installed in the air feed line piped into the screw compressor, and an inverter for controlling an operation of the motor by switching the pressure switch; and a receive tank for storing the compressed air flown in via the air feed line and then supplying the air to a field, wherein a drive control process is selectively performed by one of a Y-∆ start method, a pressure control method and a sequential control method so as to supply an optimum air demand required of the screw compressor at a field.

Description

Screw compressor control method and device

The present invention relates to a method and a control device for controlling the driving of a screw compressor, and more particularly, to a method and apparatus for automatically or manually controlling the load operation and no-load operation of the screw compressor according to the air demand.

Generally, a compressor is a mechanical device that increases pressure and speed by compressing gas or liquid. Compressors are classified into air compressors for compressing air to operate an air cylinder driving an automatic device or to operate all pneumatic devices, and compressors for refrigeration, refrigerating and air conditioners used to compress and liquefy a refrigerant. And it is divided into the compression method using the reciprocating motion of the cylinder and the piston, and the compression method using the rotational motion of the screw.

Compressor using screw method adopts Y-Δ starting method, pressure control method and multi-step control method.

In the driving method of the screw compressor operating in the Y-Δ start method, the intake valve is opened at the same time as driving the motor to inhale air to generate compressed air, and the load operation is performed to supply the generated compressed air to the receive tank. When the pressure in the receive tank exceeds the set upper limit by the load operation, the intake valve is closed by the electrical control signal, the generation of the compressed air is stopped, and the no-load operation is performed in which the motor is idle.

However, no-load operation without generating compressed air consumes about 40% of the power compared to load operation. Therefore, a considerable amount of electrical energy is consumed even when the motor is idle. Moreover, load operation and no-load operation involve a considerable amount of power consumption for starting the motor. In addition, idling the motor by no-load operation maintains idling in consideration of the consumption of about 6 to 7 times the starting current of the full load current to restart the motor in a stationary state.

Therefore, the operating method of the screw compressor operated by Y-Δ start method is advantageous when operating the workplace or equipment with air demand of more than about 85%, but the power according to no-load operation when the air demand of 85% or less is expected. Consumption was a big disadvantage.

In addition, the other one of the operation method of the screw compressor to compensate for the disadvantages of the Y-Δ start method, there is a PID (proportional, integral, differential) pressure control method. The pressure control method is to control the motor at the optimum rotation speed to generate the compressed air by the PID controller to calculate the demand of the compressed air. Therefore, it is possible to minimize the loss of the electric energy due to the low speed control of the motor and to prevent significant loss of starting power accompanying the motor restart by reducing the no-load operation time as much as possible.

However, the PID pressure control method has a problem that it is difficult to control the motor in consideration of the pressure value of the compressed air set according to the air demand, especially in the case of a compressor in which a large motor is applied. Usability was ensured only in the 50-80% range, and in the other cases, there was a problem that caused significant energy losses and even mechanical failures. In addition, if the large size of the motor installed in the screw compressor is controlled at an excessively low speed, vibration and resonance occur due to the characteristics of the large motor, causing fatal defects not only to the motor but also to adjacent parts. Because of this, there was a problem that the limit due to the low speed control of the motor was exposed.

Unlike the pressure control method, another operation method of the screw compressor is a multi-step control method. This multi-step control method is a method to prevent the power loss by stopping the motor idle itself during the no-load operation is excluded the generation of compressed air.

However, since the multi-step control method stops the driving of the motor itself during no-load operation, restarting the motor in load operation requires considerable starting power for restart. Therefore, usefulness is ensured even when power consumption for restart is only considered when the ratio of no-load operation to load operation is high, but when the no-load operation time is short compared to the load operation, the restart ratio is high and the power consumption is large. Therefore, there is a drawback that the practical utility is low, the air demand can be applied only to the workplace or facilities of less than about 50%.

The present invention is to solve all the disadvantages and problems of the control method, the object of the present invention in consideration of the air demand according to the working environment or the characteristics of the workplace and equipment to provide an optimal operating method of the compressor through real time It is possible to provide a screw compressor control method and apparatus capable of switching operation manually or automatically, and maximizing the reduction of electric energy required for driving the compressor.

In order to achieve the above object, the screw compressor control method according to the present invention, a) when the air demand is input through the control box for controlling the drive of the screw compressor, the control box according to the air demand Y-Δ starting method, pressure Setting a control method of any one of a control method and a multi-step control method; b) when the control method is set, the control box assigns the control method to the inverter for driving the motor and sets the upper limit air pressure and the lower limit air pressure of the receiver tank; c) the control box selecting a driving mode selection switch connected to the inverter to start the compressor in a corresponding control method; And d) determining whether there is an input of another operation mode selection switch during startup of the compressor.

Herein, the control box sets the Y-Δ starting method when the air demand exceeds 85%, sets the pressure control method when the air demand is in the range of 50 to 85%, and when the air demand is less than 50%. It is characterized by setting the multi-speed control method.

Here, the Y-Δ start method, the step of starting the inverter by turning on the start button provided in the control box; Driving the motor by applying power to the motor by starting the inverter; Concurrently driving the motor to turn on the solenoid valve and open the suction valve to suck air; Performing a load operation of supplying air to the receive tank through an air supply line after the compressor is operated by the motor to compress the sucked air; Transmitting a stop signal to the inverter by operating a pressure switch when a sensor detects a pressure of an air supply line and detects an upper limit set value during the load operation; Closing the intake valve by turning off the solenoid valve at the same time as the inverter idles the motor by the stop signal; Performing a no-load operation by idling the motor and releasing compressed air of the receive tank to the site; And driving a motor by operating a pressure switch when a sensor senses a pressure of an air supply line and detects a lower set value while the no-load operation is performed.

Here, the pressure control method, the step of setting a reference pressure value in the control box in consideration of the air demand; Starting the inverter by turning on a start button provided in the control box and recognizing a reference pressure value; Adjusting a rotational speed of the motor corresponding to the reference pressure value; At the same time as driving the motor at the regulated rotational speed, turning on the solenoid valve to open the suction valve to suck air; Performing a load operation of supplying air to the receive tank through an air supply line after the compressor is operated by the motor to compress the sucked air; Transmitting a stop signal to the inverter by operating a pressure switch when a sensor detects a pressure of an air supply line and detects an upper limit set value during the load operation; Closing the intake valve by turning off the solenoid valve at the same time as the inverter idles the motor by the stop signal; Performing a no-load operation by idling the motor and releasing compressed air of the receive tank to the site; And driving a motor by operating a pressure switch when a sensor senses a pressure of an air supply line and detects a lower set value while the no-load operation is performed.

Here, the multi-step speed control method may include: starting an inverter by turning on a start button provided in a control box; Driving the motor by applying power to the motor by starting the inverter; Concurrently driving the motor to turn on the solenoid valve and open the suction valve to suck air; Performing a load operation of supplying air to the receive tank through an air supply line after the compressor is operated by the motor to compress the sucked air; Transmitting a stop signal to the inverter by operating a pressure switch when a sensor detects a pressure of an air supply line and detects an upper limit set value during the load operation; The inverter stops the motor by the stop signal and closes the intake valve by turning off the solenoid valve; Performing a no-load operation by idling the motor and releasing compressed air of the receive tank to the site; And driving a motor by operating a pressure switch when a sensor senses a pressure of an air supply line and detects a lower set value while the no-load operation is performed.

In addition, in order to achieve the above object, the screw compressor control apparatus according to the present invention, the suction valve which is opened and closed by the operation of the solenoid valve and sucks or blocks the outside air, and the rotational force at a constant rotational speed with an applied power source A motor generated, a compressor for compressing and discharging air sucked through the suction valve by the rotational force of the motor, an oil separator for separating and discharging oil contained in the compressed air from the compressor, and the suction valve and the motor. Screw compressor including an air supply line for transferring the air piped to the compressor and the oil separator; A control box including a pressure switch switched according to a pressure of a pressure sensor installed in at least one air supply line piped to the screw compressor, and an inverter controlling the driving of the motor by switching of the pressure switch; And a receive tank for storing the compressed air introduced through the air supply line and supplying the compressed air to the site.

Here, a plurality of contacts are connected to the motor to control the driving of the motor by any one of a Y-Δ starting method, a pressure control method or a multi-speed control method through the inverter.

The present invention can selectively drive control by any one of the Y-Δ start method, pressure control method or multi-speed control method to supply the optimum air demand from the screw compressor in the field by the above solution means. It can cope with on-site working environment, work characteristics and other conditions, maximize the electric energy saving effect, and improve the function of screw compressor.

1 is a block diagram showing the overall configuration for controlling the drive of the screw compressor according to the present invention.

2 is an electric wiring diagram showing a part of the control box according to the present invention.

3 is a block diagram illustrating a switch connected to an inverter according to the present invention.

4 is a flowchart illustrating a method of controlling a screw compressor according to the present invention.

5 is a flowchart illustrating a method of controlling a screw compressor in a Y-Δ starting manner according to the present invention.

6 is a flowchart illustrating a method of controlling a screw compressor in a pressure control manner according to the present invention.

7 is a flowchart illustrating a method of controlling the screw compressor according to the present invention in a multi-step control method.

DETAILED DESCRIPTION Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art may easily implement the present invention. As those skilled in the art would realize, the described embodiments may be modified in various different ways, all without departing from the spirit or scope of the present invention. In the drawings, parts irrelevant to the description are omitted in order to clearly describe the present invention, and like reference numerals designate like parts throughout the specification.

Throughout the specification, when a part is said to "include" a certain component, it means that it can further include other components, without excluding other components unless specifically stated otherwise.

First, the apparatus for controlling the screw compressor of the present invention is different from the conventional way to operate in any one of the Y-Δ start method, pressure control method or multi-stage control method by combining only the advantages of the various operating methods To control the screw compressor. Moreover, it is possible to selectively apply the operation method according to the air demand required in the field.

The screw compressor 10 sucks air from the outside and then discharges the compressed air using a built-in screw compressor connected to the motor 13, and the control box 20 is a screw compressor 10. ), The receive tank 30 stores compressed air and discharges it to the facility in the field.

The suction valve 11 configured in the screw compressor 10 sucks or blocks external air by the operation of the solenoid valve opened and closed by an electrical signal. The suction valve 11 is provided at the front end of the air supply line 15. The motor 13 generates a rotating force at a constant rotational speed with an applied three-phase RST power supply. The motor 13 to be applied will vary depending on the capacity or size of the screw compressor 10 or the method of operation or rotational speed.

The compressor 12 compresses and discharges the air sucked through the suction valve 11 by the rotation of the screw by the rotational force of the motor 13. The oil separator 14 separates and discharges the oil contained in the compressed air in the compressor 12. The air supply line 15 is piped to the suction valve 11, the motor 13, the compressor 12, and the oil separator 14 to suck, transport, and discharge air. The air supply line 15 will vary in diameter, material or shape depending on the pressure between the corresponding components of the screw compressor 10.

The control box 20 is provided with one or more pressure sensors in the air supply line 15 piped to the screw compressor 10 in order to control the driving of the screw compressor 10. In particular, a plurality of pressure sensors are mounted for each of the necessary sections including the oil separator 14 in the compressor 12. In addition, the pressure sensor 21 is connected to the pressure sensor so that the pressure switch 21 is switched according to the pressure detected by the pressure sensor. Moreover, the inverter 22 which controls the drive of the motor 13 by the switching of the pressure switch 21 is comprised. The inverter 22 starts, stops or adjusts the speed of the motor 13 by the switching signal of the pressure switch 21.

The receiving tank 30 stores compressed air introduced through the air supply line 15 and supplies the compressed air to various devices or facilities installed in the field. The receiving tank 30 may have a different capacity depending on the screw compressor 10 or a different working capacity.

2 is an electrical wiring diagram showing a part of the configuration of the control box. The control box 20 is supplied with power on the RST 3 via a circuit breaker (MCCB). The inverters MI and MB for operating the motor 13 are connected in series and parallel to the inverter 22 mounted in the control box 20 via the circuit breaker MCCB. And a plurality of contacts (M, M-Δ, MY) to the motor 13 to control the driving of the motor 13 in any one of the Y-Δ start method, pressure control method or multi-step control method through the inverter 22 ) Is connected.

3 is a diagram illustrating a switch connected to an inverter. Inverter 22 is provided with a UVW that is supplied with the power of the RST three-phase is input for driving the motor 13. The inverter 22 includes a reset switch, an operation command (PID), and a switch for multi-stage speed input, and is provided with wirings for inputting DC power and analog output. An alarm line and an output line are provided for the alarm.

The apparatus for controlling the screw compressor of the present invention stores the compressed air generated by the motor 13 in the receive tank 30 via the oil separator 14. The receiving tank 30 or the air supply line 15 for supplying the compressed air is equipped with a plurality of pressure sensors having a set value for various compressed air, and each pressure sensor is connected to the corresponding pressure switch 21. . In addition, an inverter 22 for controlling the driving of the motor 13 according to the detection signals transmitted from the plurality of pressure switches 21 is provided. The inverter 22 is connected to the control box 20, the control box 20 includes a variety of operation switches required for the operator's operation.

The control method according to the screw compressor control apparatus of the present invention configured as described above will be described with reference to the flowchart of FIG. 4 and the flowcharts of FIGS. 5 to 7.

First, when the air demand is input through the control box 20 that controls the driving of the screw compressor 10 (S1), the control box 20 is Y-Δ start method, pressure control method or multi-step depending on the air demand One of the control methods is set (S2). When the control method is set in step S2, the control box 20 assigns the control method to the inverter 22 for driving the motor 13 (S3), and the upper and lower air pressures of the receiver tank 30 are controlled. Set (S4). The control box 20 selects an operation method selection switch connected to the inverter 22 (S5), and activates the screw compressor 10 in a corresponding control method (S6). During startup of the screw compressor 10, it is determined whether there is an input of another operation method selection switch (S7).

The detailed operation of the operation method for the operation of the screw compressor 10 will be described below.

The control box 20 sets the Y-Δ start method when the air demand exceeds 85%, sets the pressure control method when the air demand is in the range of 50 to 85%, and when the air demand is less than 50%. By setting a multi-step control method to control the operation of the screw compressor (10).

When the air demand from the screw compressor 10 exceeds 85%, it is operated by the Y-Δ starting method, which is the flow chart of FIG. That is, by turning on the start button provided in the control box 20 (S10) to start the inverter 22 (S11). The power is applied to the motor 13 by starting the inverter 22 (S12) to drive the motor 13 (S13). At the same time as driving of the motor 13, the solenoid valve is turned on to open the suction valve 11 to suck in air (S14). The compressor 12 is operated by the driving of the motor 13 to compress the sucked air and then perform a load operation for supplying air to the receive tank 30 through the air supply line 15 (15). When the sensor senses the pressure of the air supply line 15 during the load operation and detects the upper limit set value, the pressure switch 21 is operated to send a stop signal to the inverter 22 (S17). In response to the stop signal, the inverter 22 idles the motor 13 (S18), turns off the solenoid valve, and closes the intake valve 11 (S19). Therefore, no-load operation is performed by idling the motor 13 (S20), and releases the compressed air of the receive tank 30 to the site (S21). When the sensor detects the pressure of the air supply line 15 and detects the lower limit while the no load operation is performed, the pressure switch 21 is operated to re-drive the motor 13 (S22).

As described above, in the method of operating the screw compressor by the Y-Δ starting method, when the air pressure measured from the pressure switch 21 reaches the upper limit set value, no load operation is performed in which no compressed air is generated, and thus the motor 13 and the compressor 12 are operated. In between, idling occurs. When the air pressure measured from the pressure switch 21 reaches the lower limit set value, a load operation for generating compressed air is performed to substantially drive the motor 13 and the compressor 12.

Therefore, the Y-Δ start method is a load operation in which the compressed air is generated by driving the motor 13 while the inverter 22 operates as an input of the start button of the control box 20, opening the suction valve 11, If the air pressure measured from the pressure switch 21 during the generation of compressed air is the upper limit set value, the motor 13 is idling according to the command of the inverter 22, the intake valve 11 is closed, and the receiver tank 30 is Compressed air is released with no load operation. After that, if the air pressure measured from the pressure switch 21 is a lower limit set value, the motor 13 is normally driven again to perform a repeating operation. In the Y-Δ start method, the motor is idle at no load operation without generating compressed air, and a considerable amount of power consumption is expected.

Next, when the air demand from the screw compressor 10 is in the range of 50 to 85%, it is operated in a pressure control method, which is the flowchart of FIG. 6. That is, the reference pressure value is set in the control box 20 in consideration of the air demand (S30). The start button provided in the control box 20 is turned on (S31), the inverter 22 is started, and the reference pressure value is recognized (S32). And it adjusts the rotational speed of the motor 13 corresponding to the recognized reference pressure value (S33). The motor 13 is driven at the adjusted rotation speed (S34), and the solenoid valve is turned on to open the suction valve 11 to suck air (S35). After the compressor 12 is operated by the driving of the motor 13 to compress the sucked air, a load operation for supplying air to the receive tank 30 through the air supply line 15 is performed (S36). When the sensor senses the pressure of the air supply line 15 during the load operation and detects the upper limit set value (S37), the pressure switch 21 is operated to send a stop signal to the inverter 22 (S38). In response to the stop signal, the inverter 22 idles the motor 13 (S39), turns off the solenoid valve, and closes the suction valve 11 (S40). Therefore, no-load operation is performed by idling of the motor 13 (S41), and the compressed air of the receiving tank 30 is discharged to the site (S42). When the sensor detects the pressure of the air supply line 15 and detects the lower limit while the no load operation is performed, the pressure switch 21 is operated to restart the motor 13 (S43).

As described above, the screw compressor operating method using the pressure control method sets a reference pressure value having a constant value in consideration of the air demand and then controls the rotation speed of the motor corresponding to the reference pressure.

Therefore, in the pressure control method, when the start button is operated and the inverter 22 operates, the motor 13 is driven. At this time, the inverter 22 recognizes the preset pressure setting value and then drives the motor at a rotation speed corresponding to the pressure setting value. Then, the intake valve 11 is opened to perform a load operation in which compressed air is generated. If the air pressure measured from the pressure switch 21 during the generation of the compressed air by the load operation is the upper limit set value, the motor 13 is idling according to the command of the inverter 22, the intake valve 11 is closed, and the receive tank ( 30) A no load operation is performed to release the compressed air inside. After that, if the air pressure measured from the pressure switch 21 is a lower limit set value, the motor 13 is normally driven again to perform a repeating operation. The pressure control method can reduce the no-load operation time by setting the air pressure to be generated in advance and then drive the motor 13 at a rotational speed corresponding to the pressure set value, but it is difficult to apply a high rotational deceleration ratio. There is a limit to the effect of reducing the electrical energy.

In addition, when the air demand from the screw compressor 10 is less than 50% is operated in a multi-speed control method, which is the same as the flow chart of FIG. That is, by turning on the start button provided in the control box 20 (S50) to start the inverter 22 (S51). When power is applied to the motor 13 by starting the inverter 22 (S52), the motor 13 is driven (S53). At the same time as driving of the motor 13, the solenoid valve is turned on and the suction valve is opened to suck air (S54). After the compressor 12 is operated by the driving of the motor 13 to compress the sucked air, a load operation for supplying air to the receive tank 30 through the air supply line 15 is performed (S55). When the sensor senses the pressure of the air supply line 15 during the load operation and detects the upper limit set value (S56), the pressure switch 21 is operated to send a stop signal to the inverter 22 (S57). In response to the stop signal, the inverter 22 stops the motor 13 (S58), turns off the solenoid valve, and closes the intake valve 11 (S59). Therefore, no-load operation is performed by idling of the motor 13 (S60), and the compressed air of the receiving tank 30 is discharged to the field equipment (S61). When the sensor detects the pressure of the air supply line 15 and detects the lower limit while the no load operation is performed, the pressure switch 21 is operated to restart the motor 13 (S62).

As described above, in the screw compressor operating method using the multi-stage control method, when the air pressure measured from the pressure switch 21 reaches the upper limit value, no load operation is performed without generating compressed air to stop the operation of the motor 13. When the air pressure measured from the pressure switch 21 reaches the lower limit set value, a load operation without generating compressed air is performed to re-drive the motor 13 to repeat the operation.

Therefore, in the multi-stage control method, the inverter 22 is operated as an input to the start button to drive the motor 13, and load operation is performed to generate compressed air by opening the intake valve 11. When the air pressure measured from the pressure switch 21 is the upper limit set value while the compressed air is generated by the load operation, the motor 13 is stopped according to the instruction of the inverter 22, and the intake valve 11 is closed. , The compressed air in the receiving tank 30 is carried out a no-load operation is discharged to the on-site equipment. After that, when the air pressure measured from the pressure switch 21 is a lower limit set value, it is restarted again and repeated operation is performed. Since the multi-step control method stops the operation of the motor 13 during no load operation without generating compressed air, there is no loss of electrical energy due to the stop of the motor. However, if the measured air pressure is a lower limit value, the motor 13 There is some loss of electrical energy due to the need to restart).

As such, in order to control the screw compressor of the present invention, the Y-Δ starting method, the pressure control method, or the multi-step control method, in which the electric and electronic circuits for controlling the single compressor, can be selectively set. According to the driving method, for example, when the air demand exceeds 85%, in the range of 50 to 85%, or less than 50%, an operation method suitable for each air demand may be automatically or manually selected. Therefore, instant and optimal operation can be applied in one screw compressor system even in the field characteristics or environment, which can change from time to time, thereby maximizing the electric energy saving effect according to the operation of the screw compressor.

Moreover, the air demand of the screw compressor can be changed in various ways depending on the characteristics of the field workplace, the environment, and the type of air use by the operator.

Therefore, the control method of the screw compressor of the present invention proposes a variety of operation methods that can be selected to solve the disadvantage that does not meet the predictable demand by using a predetermined screw compressor in one operation method.

The foregoing description of the present invention is intended for illustration, and it will be understood by those skilled in the art that the present invention may be easily modified in other specific forms without changing the technical spirit or essential features of the present invention. will be. Therefore, it should be understood that the embodiments described above are exemplary in all respects and not restrictive.

The scope of the present invention is shown by the following claims rather than the above description, and all changes or modifications derived from the meaning and scope of the claims and their equivalents should be construed as being included in the scope of the present invention. do.

Claims

a) when the air demand is input through the control box for controlling the operation of the screw compressor, the control box sets a control method of any one of a Y-Δ starting method, a pressure control method or a multi-step control method according to the air demand;

b) when the control method is set, the control box assigns the control method to the inverter for driving the motor and sets the upper limit air pressure and the lower limit air pressure of the receiver tank;

c) the control box selecting a driving mode selection switch connected to the inverter to start the compressor in a corresponding control method; And

d) determining whether there is an input of another operation mode selection switch during startup of the compressor;

Screw compressor control method comprising a.
The method of claim 1,

The control box sets the Y-Δ starting method when the air demand exceeds 85%, sets the pressure control method when the air demand is in the range of 50 to 85%, and multi-steps when the air demand is less than 50%. Screw compressor control method to set the control method.
The method of claim 1, wherein the Y-Δ start method,

Starting the inverter by turning on a start button provided in the control box;

Driving the motor by applying power to the motor by starting the inverter;

Concurrently driving the motor to turn on the solenoid valve and open the suction valve to suck air;

Performing a load operation of supplying air to the receive tank through an air supply line after the compressor is operated by the motor to compress the sucked air;

Transmitting a stop signal to the inverter by operating a pressure switch when a sensor detects a pressure of an air supply line and detects an upper limit set value during the load operation;

Closing the intake valve by turning off the solenoid valve at the same time as the inverter idles the motor by the stop signal;

Performing a no-load operation by idling the motor and releasing compressed air of the receive tank to the site; And

When the sensor detects the pressure of the air supply line during the no load operation and detects the lower limit set value, driving the motor by operating the pressure switch.

Screw compressor control method comprising a.
The method of claim 1, wherein the pressure control method,

Setting a reference pressure value in the control box in consideration of the air demand;

Starting the inverter by turning on a start button provided in the control box and recognizing a reference pressure value;

Adjusting a rotational speed of the motor corresponding to the reference pressure value;

At the same time as driving the motor at the regulated rotational speed, turning on the solenoid valve to open the suction valve to suck air;

Performing a load operation of supplying air to the receive tank through an air supply line after the compressor is operated by the motor to compress the sucked air;

Transmitting a stop signal to the inverter by operating a pressure switch when a sensor detects a pressure of an air supply line and detects an upper limit set value during the load operation;

Closing the intake valve by turning off the solenoid valve at the same time as the inverter idles the motor by the stop signal;

Performing a no-load operation by idling the motor and releasing compressed air of the receive tank to the site; And

When the sensor detects the pressure of the air supply line during the no load operation and detects the lower limit set value, driving the motor by operating the pressure switch.

Screw compressor control method comprising a.
According to claim 1, The multi-step speed control method,

Starting the inverter by turning on a start button provided in the control box;

Driving the motor by applying power to the motor by starting the inverter;

Concurrently driving the motor to turn on the solenoid valve and open the suction valve to suck air;

Performing a load operation of supplying air to the receive tank through an air supply line after the compressor is operated by the motor to compress the sucked air;

Transmitting a stop signal to the inverter by operating a pressure switch when a sensor detects a pressure of an air supply line and detects an upper limit set value during the load operation;

The inverter stops the motor by the stop signal and closes the intake valve by turning off the solenoid valve;

Performing a no-load operation by idling the motor and releasing compressed air of the receive tank to the site; And

When the sensor detects the pressure of the air supply line during the no load operation and detects the lower limit set value, driving the motor by operating the pressure switch.

Screw compressor control method comprising a.
A suction valve which is opened and closed by the operation of the solenoid valve to suck or block external air, a motor which generates rotational force at a predetermined rotational speed with an applied power source, and compresses the air sucked through the suction valve by the rotational force of the motor And a compressor including a compressor, an oil separator for separating and discharging oil contained in the compressed air from the compressor, and an air supply line piped to the suction valve, the motor, the compressor, and the oil separator for transferring air. Compressor;

A control box including a pressure switch switched according to a pressure of a pressure sensor installed in at least one air supply line piped to the screw compressor, and an inverter controlling the driving of the motor by switching of the pressure switch; And

Receive tank that stores the compressed air introduced through the air supply line and supplies to the site

Screw compressor control device comprising a.
The method of claim 6,

Screw compressor control device characterized in that a plurality of contacts are connected to the motor to control the driving of the motor by any one of the Y-Δ start method, pressure control method or multi-speed control method through the inverter.