JP6940686B2 - Gas compressor - Google Patents

Description

The present invention relates to a gas compressor and relates to a gas compressor that reduces a driving load.

For example, in a gas compressor that sucks a gas such as air and generates a high-pressure compressed gas by a compression mechanism such as a positive displacement type or a turbo type, various operation control methods for reducing a drive load have been conventionally known.

In a constant-speed compressor that fixes the rotation of the drive source to a constant speed, when the discharge pressure reaches the target pressure desired by the user, the suction throttle valve installed in the intake passage of the compressor body is closed to reduce the amount of inflowing gas. No-load operation control that reduces the power load by limiting is known. In such no-load operation, the required power consumption can be reduced to about 70% of the rated power.

Further, in a variable speed controlled gas compressor that changes the rotation speed of a motor using a power conversion device such as an inverter, the power conversion device operates at a high rotation speed (full speed) until the target pressure is reached, and the discharge pressure is the same. When the pressure is exceeded, a power conversion device reduces the number of revolutions to reduce the power.

For example, if the amount of compressed gas used on the user (consumer of compressed gas) side is large and the discharge pressure on the user side is lower than the target pressure, the operation is performed at the maximum rotation speed at the rated speed, and eventually the amount used on the user side. When the discharge pressure on the user side exceeds the target pressure, the rotation speed is reduced to reduce the power. As a control for changing the rotation speed, a control method called P, PI or PID, which changes the rotation speed in proportion to the discharge pressure, is generally known.

Further, in the variable speed control gas compressor, as a technique for further reducing the power, a no-load operation method using a suction throttle valve and an air release valve in addition to the rotation speed control by the power conversion device is known. For example, Patent Document 1 is an air compressor, which performs PID control operation based on a target pressure (P0), but the amount of air used on the user side decreases, and the discharge pressure on the user side ranges from P0 to a predetermined pressure. When the pressure is increased, control is performed to reduce the rotation speed while maintaining the rotation speed in a predetermined pressure range of P0 or higher or higher than P0. More specifically, when the pressure rises to an upper limit pressure (P1) higher than P0, the suction throttle valve is closed, the rotation speed of the motor is lowered to the lower limit rotation speed to reduce the power, and the discharge port on the user side. This is an operation method in which compressed air on the upstream side is released to the atmosphere to reduce the load of the compressor body (load of the motor) and further reduce the power.

Further, in Patent Document 1, the upper limit pressure P1 is reached and the motor is operated at the lower limit rotation speed, but the amount of air used on the user side gradually increases, and the discharge pressure on the user side is a pressure between P0 and P1. Also disclosed is a control in which when the lower limit pressure (P2) is reached, the air release valve is closed and / or the suction throttle valve is opened while the rotation speed remains at the lower limit rotation speed, and a load operation is performed in which the pressure is increased until P1 is reached again. This is a technology that can reduce power while keeping the pressure on the user side within a certain range. The power consumption required during such no-load operation can be about 30% of the rated power.
It should be noted that the opening / closing control of the throttle valve and the air release are not necessarily used in combination, and either one of them has a considerable power reduction effect.

Japanese Unexamined Patent Publication No. 2001-280275

By the way, in Patent Document 1, during no-load and load operation, the number of revolutions of the motor is set as the lower limit to save energy, but the compressor causes pressure fluctuations with respect to changes in the usage state of compressed air. Even if the amount of discharged air is constant, the pressure also fluctuates if the amount of compressed air used changes. When a specific pressure (or more) is required for the compressed air pressure, if the amount used is too large, the compressed air may not be generated in time and may fall below the specific pressure. That is, the ability to follow changes in the amount used is reduced.

In response to such pressure fluctuations, in a gas compressor, the downstream pipe of the discharge port on the user side is generally connected to a gas tank (also referred to as a reservoir tank) for storing compressed gas, and each is connected from the gas tank via a pipe. The configuration is such that the compressed gas is supplied to the terminal equipment on the user side. That is, it can be said that various operation controls for reducing power as described above can be efficiently realized when the gas tank has a certain volume.

If the volume is large, the gas tank functions as a constant buffer for pressure fluctuations with respect to changes in the amount of compressed gas used at the end on the user side, and the ratio of differential pressure fluctuations required for the compressor body can be kept within a relatively small range. can. As a result, the compressor can reduce the frequency of changes in the number of revolutions, which also contributes to the reduction of power. In addition, the reduction of sudden pressure fluctuations also contributes to the prevention of hunting and tripping of drive sources such as motors.

As described above, the volume of the gas tank required to function as a buffer for pressure fluctuation is relatively large, and even if the compressor is miniaturized, it is necessary to secure an installation space in the configuration of the actual usage environment.

A technology for reducing power while maintaining the ability to follow pressure fluctuations is desired. Further, a technique for saving space in compressor equipment is desired.

In order to solve the above problems, for example, the configuration described in the claims is applied. That is, the compressor main body that sucks in gas and discharges the compressed gas, the pressure detection device that detects the discharge pressure of the compressed gas, the drive source of the compressor main body, and the drive source according to the detection value of the pressure detection device. A gas compressor having a control device for controlling at a variable speed, in which the rotation speed of the drive source becomes the full speed rotation speed when the discharge pressure is the set pressure P0, and the discharge pressure is the said. When the set pressure P0 rises to the upper limit pressure P1, the rotation speed of the drive source decreases from the full speed rotation speed to the lower limit rotation speed, and the full speed is relative to the discharge pressure from the set pressure P0 to the upper limit pressure P1. The configuration is such that the rotation speed of the drive source is controlled so that the rotation speed of the drive source from the rotation speed to the lower limit rotation speed is proportional.

According to the present invention, it is possible to improve the followability of the gas compressor to pressure fluctuations and reduce the power load. Furthermore, it also contributes to space saving of compressor equipment including a gas tank.

It is a block diagram which shows typically the structure of the air compressor according to Example 1 to which this invention was applied. It is a transition diagram which schematically shows the transition such as the pressure and the rotation speed of the air compressor according to Example 1. It is a block diagram which shows typically the structure of the air compressor by Example 2 to which this invention was applied. It is a transition diagram which shows typically the transition such as the pressure and the rotation speed of the air compressor according to Example 2.

Hereinafter, modes for carrying out the invention will be described with reference to the drawings.

FIG. 1 schematically shows the configuration of an air compressor 50 (hereinafter, may be referred to as “compressor 50”) which is an example of an embodiment to which the present invention is applied.

The compressor 50 mainly includes a compressor main body 1, an electric motor 2, a power converter 3, a control device 4, a gas-liquid separator 12, an air cooler 16, a pressure sensor 17, an oil cooler 21, and a fan device 25. It has a package type compressor structure in which the front, rear, left and right sides and the upper surface are surrounded by the panel 40.

The compressor main body 1 has a compression mechanism such as a positive displacement type or a turbo type, and compresses the air sucked from the suction filter 8. Lubricating oil is supplied to the compression operating chamber of the compressor main body 1 via an oil pipe 20, and a gas-liquid mixed compressed gas is discharged together with air.
In this embodiment, a rotary screw rotor will be described as being provided as a compression mechanism.

The electric motor 2 is a drive source for the compressor main body 1. An internal combustion engine can also be applied as the drive source. The electric motor 2 supplies the rotational force due to the electric power to the screw rotor of the compressor main body 1 by the same axis or via a belt or a gear. The power conversion device converts the frequency of the electric power supplied to the electric motor 2 based on the command from the control device 4 to change the rotation speed of the electric motor 2.

The control device 4 includes a semiconductor arithmetic unit such as an MPU and a CPU and a storage device, and realizes a functional unit that controls the entire compressor 50 in cooperation with a program. The control device 4 can also be configured from an analog circuit configuration and a combination thereof. The control device 4 receives input of a detection value from the temperature sensor 11 that detects the discharge gas temperature and the pressure sensor 17 that detects the pressure of the discharge gas, outputs a frequency command to the power conversion device 3, and outputs various valve bodies. It is designed to output open / close commands. Details will be described later.

The gas-liquid separator 12 is a separator that firstly separates oil from the compressed gas of the gas-liquid mixture discharged from the compressor main body 1. In this embodiment, the swirl separation type that separates oil and air by centrifugal force by swirling the compressed gas in the inner cylinder is applied, but the collision separation type can also be applied. The separated oil is stored in the bottom of the gas-liquid separator 12, is conveyed to the oil cooler 21 via the oil pipe 20 by the air pressure in the gas-liquid separator 12 or the pump 23, and is cooled to a predetermined temperature. After that, it is returned to the compressor main body 1.

The secondary filter 13 is provided with, for example, a non-woven fabric or the like, and performs secondary separation of compressed air primary separated from oil by a gas-liquid separator 12. The secondarily separated compressed air flows to the discharge pipe on the downstream side and flows to the air cooler 16 via the check valve 15 that allows distribution to the downstream side.

Air cooler 16 is heat exchange換機, that the fan device 25 is driven, the outside air from the intake port 30 is sucked into the compressor 50 as cooling air is adapted to be discharged from the exhaust port 32 to the outside .. The fan device 25 is controlled at a variable speed according to the detection value of the temperature sensor 11. An electromagnetic three-way valve 22 and a bypass pipe 24 are arranged upstream of the oil cooler 21, and the control device 4 recirculates the lubricating oil flow from the gas-liquid separator 12 according to the detected value of the temperature sensor 11. It is designed to control the switching of the path and the driving state of the pump 23. Air cooler 16, by compressed air and the fan unit 25 heated to high temperature by the compression action is cooling air and heat exchange conversion for generating the compressed air predetermined temperature (e.g., 70 degrees) cooled to.
With these cooling systems, the cooling air cools the motor 2 and the compressor body 1 by air, and then flows to the air cooler 16 and the oil cooler 21 on the downstream side to exchange heat with each cooler.

A pressure sensor 17 is arranged on the pipeline from the outlet of the air cooler 16 to the external pipe 59 (or may be on the external pipe 59). The pressure sensor 17 is connected to the control device 4 so as to be capable of control communication, and outputs the pressure value of the compressed air discharged from the compressor 50 to the control device 4. The control device 4 monitors the input value from the pressure sensor 17 and outputs a frequency command and a valve body opening / closing command according to a set pressure, an upper limit pressure, and the like, which will be described later.

The compressed air cooled to a predetermined temperature by the air cooler 16 is then discharged from the compressor 50 via the external pipe 59. The external pipe 59 is connected to the gas tank 60. The gas tank 60 is a pressure vessel that stores compressed gas at a predetermined pressure. The compressed air is supplied from the gas tank 60 to the terminal equipment using the compressed air via a terminal pipe (not shown).

Further, a suction throttle valve 5 is arranged on the suction side of the compressor main body 1 (downstream of the suction filter 8). The suction throttle valve 5 is a valve body that permits / restricts the inflow of intake air from the suction port into the compression operation chamber of the compressor main body 1 according to the operating state of the compressor 50. In the present embodiment, the suction throttle valve 5 will be described as having a configuration in which the piston as a valve body opens and closes using the discharge pressure of the compressor main body 1 as an operating source, but an electromagnetic valve or another pressure may be used as an operating source. The opening and closing of the suction throttle valve 5 is executed by the control device 4.

One of the features of this embodiment is that the suction throttle valve 5 closes when the upper limit pressure P1 described later is reached. More specifically, the suction throttle valve 5 is fully open until the upper limit pressure P1 is reached, and is closed when the upper limit pressure P1 is reached.

Next, the control of the control device 4 will be described in detail.
FIG. 2 shows the discharge pressure, the rotation speed of the motor 2 (frequency of the power conversion device 3), and the state transition of the suction throttle valve 5 in chronological order according to this embodiment. In the figure, the set pressure is P0 and the upper limit pressure is P1, and 0.70 Mpa and 0.80 Mpa are taken as examples, respectively. The set pressure is an arbitrary setting input or an initial setting pressure from the user side, and is a pressure value targeted by the compressor 50 for discharge. The upper limit pressure is the maximum discharge pressure determined by the equipment rating specifications, and is the pressure value determined by equipment maintenance and various safety standards. In this embodiment, a pressure lower than the safety pressure according to the safety standard will be described as the upper limit pressure P1.

Further, the full speed rotation speed of the motor 2 is 6000 rpm / min, and the lower limit rotation speed is 800 rpm / min as an example. The full speed rotation speed is the maximum rated rotation speed of the motor 2, and the lower limit rotation speed is a predetermined rotation speed lower than this. For example, it is the minimum rotation speed that can be taken when driving a compressor such as load operation and no-load operation shown in Patent Document 1.
In the figure, for the sake of simplicity, the transition of pressure and rotation speed is schematically shown, and the present invention is not necessarily limited to the numerical values shown.

First, the control device 4 is adapted to perform PID control with a target of a predetermined set pressure P0 input by, for example, a user or the like. That according to the fluctuation of the discharge pressure, by changing the frequency value output from the power converter 3, a control to increase or decrease the discharge amount of air of the compressor body 1. In addition, P or PI control may be applied.

When the compressor 50 starts operation at the time t0 to t1 of FIG. 2, the control device 4 outputs a frequency command value to the power conversion device 3 so that the motor 2 operates at the rated full speed at a predetermined acceleration rate. , The operation is performed by PID control so that the input value from the pressure sensor 17 becomes P0. At this time, the suction throttle valve 5 is open.

Then, at time t1 to t2, when the amount of compressed air used on the user side decreases (for example, the amount used is about 20%) and the discharge pressure is higher than the set pressure P0, the control device 4 rotates at full speed. A command of a predetermined frequency between the number and the lower limit rotation speed is output to the power conversion device 3 (full speed rotation frequency> predetermined frequency> lower limit rotation). More specifically, as the discharge pressure rises from P0, the predetermined frequency is gradually reduced to reduce the rotation speed of the motor. In this embodiment, in the pressure band higher than the set pressure P0 and less than the upper limit pressure P1, the corresponding rotation speed is proportional to the pressure value, but the higher the discharge pressure, the lower the rotation speed. The discharge pressure and the corresponding rotation speed may be biased by increasing the ratio or increasing the decrease ratio of the rotation speed as the discharge pressure is lower. Further, the frequency may be changed stepwise by increasing or decreasing a predetermined number of revolutions for each predetermined pressure width in the pressure band.

In this way, when the discharge pressure exceeds the set pressure P0, the control device 4 operates the compressor main body 1 with frequency control in which the rotation speed is higher than the lower limit rotation speed and lower than the full speed. It has become like. Further, from t1 to t2, the suction throttle valve 5 is fully open.

Then, at time t2-, when the amount of compressed air used is further reduced, the discharge pressure is further increased and eventually reaches the upper limit pressure (P1). When the discharge pressure reaches the upper limit pressure P1, the controller 4 outputs the frequency command value as the lower limit rotation speed to the power converter 3 also a suction throttle valve 5 outputs a control command to close (C lose). As a result, the pressure rise of the pressure sensor 17 is stopped.

That is, as one of the features of this embodiment, when the discharge pressure is between the set pressure P0 and the upper limit pressure P1, the compressor main body 1 is operated at a rotation speed less than the full speed rotation speed and higher than the lower limit rotation speed. .. That is, in the case where the discharge pressure is higher than P0 and lower than P1, since the operation is performed at a rotation speed higher than the lower limit rotation speed, the discharge pressure fluctuates more than when operating at the lower limit rotation speed in the pressure band. On the other hand, it has the effect of improving followability.

For example, when the discharge pressure exceeds P0 due to the decrease in the amount of compressed air used, the amount of discharged air in the compressor body 1 is reduced with the rotation speed as the lower limit, but then the amount of compressed air used increases again. think.
The pressure in the gas tank 60 decreases as the amount of air used increases again, but even if full-speed operation is restarted from the lower limit rotation speed in order to increase the amount of discharged air in the compressor body 1 in response to the decrease. There will be a time lag before the number of revolutions reaches full speed. That is, it is difficult to operate beyond the acceleration rate in order to avoid trips due to inertia of the motor 2 and the compressor body 1 and to maintain the power conversion device 3 by outputting a sudden overcurrent. Therefore, there is a time lag until the compressor main body 1 discharges an amount of air equal to or greater than the re-increased amount of air used, and if the amount of increased air used is larger, the compressed air pressure on the user side sets the set pressure P0. It may be lower.

On the other hand, in this embodiment, when the discharge pressure is higher than the set pressure P0 and is lower than the upper limit pressure P1, the compressor main body 1 is operated at a rotation speed less than the full speed rotation speed and a rotation speed higher than the lower limit rotation speed. Therefore, when the amount of air used is increased again as described above, the time for returning the operation of the compressor main body 1 to the one at the full speed rotation speed can be relatively shortened.

Further, since the rotation between the set pressure P0 and the upper limit pressure P1 is lower than the full speed rotation, the effect of reducing the power consumption by that amount can be expected, and further, the power required for boosting can be reduced. You can also expect the energy saving effect.

For example, in the conventional suction throttle valve control, the suction throttle valve is gradually closed between the set pressure P0 and the upper limit pressure P1 (the ratio of the amount of air used decreases), so that the intake pressure of the compressor also gradually decreases. Then, when fully closed, the pressure drops to almost the vacuum pressure. That is, the compressor main body 1 is driven by a pressure difference of a vacuum pressure on the suction side and an upper limit pressure P1 on the discharge side.
On the other hand, in this embodiment, the suction throttle valve 5 remains fully open even if the ratio of the amount of air used decreases. Therefore, the intake pressure of the compressor main body 1 remains substantially atmospheric pressure. That is, as the intake pressure of the compressor main body 1 decreases toward the upper limit pressure, the boosting amount increases, but in the case of this embodiment, the boosting amount for reaching the upper limit pressure is sufficient, and the energy saving effect increases accordingly. ..

Further, when the gas tank 60 is provided as in this embodiment, the volume of the gas tank 60 can be reduced. Generally, the gas tank 60 has a role of alleviating pressure fluctuations due to an increase or decrease in the amount of air used. In other words, since the pressure is often due to fluctuations in the amount of air, by storing a certain amount of compressed air in advance with respect to the amount used, it functions as a buffer to reduce the range of pressure fluctuations associated with use. be able to. In this embodiment, since the followability to the pressure fluctuation is improved, the volume of the gas tank 60 can be reduced accordingly.

Hereinafter, the effect of improving the followability and the effect of making the volume of the gas tank 60 smaller can be described with reference to the present embodiment.
For example, when the working air volume ratio is 100%, the air volume is 6 m3 (cubic meter) / min, the volume of the gas-liquid separator 12 is 30 L, the discharge air temperature is 80 ° C., the set pressure P0 is 0.7 MPa, and the upper limit pressure P1 is 0. It is set to 0.8 MPa. When the working air amount ratio is around 0%, the pressure in the gas-liquid separator 12 becomes the upper limit pressure P1 (0.8 MPa). After that, it is necessary to operate the compressor main body 1 so that the set pressure (0.7 MPa) can be secured even when the air amount ratio on the user side becomes 100%.

Here, the time t at which the pressure in the gas-liquid separator 12 (detected value of the pressure sensor 17) drops from 0.80 MPa to 0.70 MPa is calculated by the following mathematical formula 1 to be about 0.3 seconds.

The target pressure P0 cannot be secured unless the time for returning to full speed rotation is set to 0.3 seconds or less. If the motor 2 has a specification that requires 6 seconds to accelerate from stop to full speed, and the power consumption ratio at the upper limit pressure P1 is 65%, the time required to reach full speed is about 2 seconds, which is 1.7 seconds. Is lower than the target pressure P0. Therefore, in this embodiment, in order to maintain the target pressure P0, an air tank of about 0.2 m3 is required downstream of the compressor 50.

On the other hand, with a compressor equivalent to a discharge air amount of 6 m3 / min, a constant speed machine and a variable speed machine that gradually close the suction throttle valve with the rotation speed as the lower limit rotation speed between the target pressure P0 and the upper limit pressure P1. The gas tank required for this is as follows.

・ Constant speed machine ≒ 0.7m3 (3.5 times that of this example)
-Variable speed machine ≒ 0.4 m3 (twice as much as this example)
As described above, it can be seen that this embodiment exerts a remarkable effect in improving the followability to pressure fluctuations and downsizing the gas tank.

Next, Example 2 to which the present invention is applied will be described.
FIG. 3 schematically shows the configuration of the compressor 100 according to the second embodiment. The same reference numerals may be used for the configurations common to those in the first embodiment, and detailed description may be omitted.
The main difference from the compressor 50 of the first embodiment is that the compressor 100 of the second embodiment does not include the suction throttle valve 5. Further, the compressor 100 includes an air release valve 14 between the check valve 15 and the secondary filter 13 in the discharge pipe 10.

The air release valve 14 is an air release means for releasing compressed air from the compressor main body 1 to the check valve 15 to the atmosphere, and is composed of a valve body. For example, it is composed of a solenoid valve and the like, and is opened and closed by a control command of the control device 4. It may be composed of a mechanical valve body that opens at a predetermined pressure by a force of force such as a spring. In this embodiment, the predetermined pressure is the upper limit pressure P1.
Although not shown, the air release valve 14 is connected to the suction side (between the suction filter 8 and the suction port) of the compressor main body 1 to release compressed air. Not limited to this, air may be directly released to any space inside the package or to the outside.

In this embodiment, the control device 4 opens the air release valve when the detection value of the pressure sensor 17 detects the upper limit pressure P1. That is, from the set pressure P0 to the upper limit pressure P1, the control device 4 drives the motor 2 at a frequency in a range lower than the full speed and higher than the lower limit rotation speed, as in the first embodiment. One of the features is that when the upper limit pressure P1 or more is reached, the air release valve 14 is opened to reduce the power load.

FIG. 4 shows the discharge pressure according to the second embodiment, the rotation speed of the electric motor 2 (frequency of the power conversion device 3), and the state transition of the air release valve 14 in chronological order. The numerical values such as the set pressure P0 and the upper limit pressure P1 are the same as those in FIG. 2 of the first embodiment.

At the time t0 to t1 of FIG. 4, the controller 4 drives the motor 2 so that the motor 2 operates at the rated full speed at a predetermined acceleration rate so that the input value from the pressure sensor 17 becomes P0. Operate under PID control. At this time, the air release valve 14 is closed.

Then, at time t1 to t2, when the amount of compressed air used on the user side decreases (for example, the amount used is about 20%) and the discharge pressure is higher than the set pressure P0, the control device 4 rotates at full speed. A command of a predetermined frequency between the number and the lower limit rotation speed is output to the power conversion device 3 (full speed rotation frequency> predetermined frequency> lower limit rotation).

Then, at time t2-, when the amount of compressed air used is further reduced, the discharge pressure is further increased and eventually reaches the upper limit pressure (P1). When the discharge pressure reaches the upper limit pressure P1, the control device 4 outputs a frequency command value, which is the lower limit rotation speed, to the power conversion device 3 and outputs a control command for opening the air release valve 14. As a result, the pressure rise of the pressure sensor 17 is stopped, and the pressure upstream from the check valve 15 is reduced.
Although not shown, the discharge pipe 10 is provided with a pressure holding valve, and is provided with a valve body that releases air for safety when the safety pressure becomes higher than the upper limit pressure P1.

According to the second embodiment, as in the first embodiment, the effects of improving the followability to the pressure fluctuation and downsizing the gas tank can be expected. Further, it is possible to reduce the power consumption by the amount of rotation at a rotation speed lower than the full speed rotation, such as between t1 to t2.

Although the embodiment for carrying out the present invention has been described above, the present invention is not limited to the above-mentioned various examples, and various modifications and substitutions can be made without departing from the spirit of the present invention.

For example, in the first embodiment, closing the intake Komishibo Riben 5 reaches the upper limit pressure P1, has been opened Hokiben 14 In Example 2, it is also possible to and controlled with both these .. At the upper limit pressure P1 or higher, the energy saving effect of both can be further expected.

Further, in Examples 1 and 2, the suction throttle valve 5 was closed or the air release valve 14 was opened at the upper limit pressure P1, but after that, the amount of compressed air used increased and the pressure became lower than P1. If it may be adapted to close the opening or Hokiben 14 suction Komishibo Riben 5. Further, when the upper limit pressure P1 continues for a predetermined time, the driving of the compressors 50 and 100 may be automatically stopped. As the predetermined time, the duration of the upper limit pressure P1 and the load factor (ratio of the operation duration at the full speed rotation speed to the operation time at the rotation speed lower than the full speed) in the predetermined time until immediately before can be raised. In addition to these, the compressors 50 and 100 may be stopped in consideration of the minimum operating time (maintenance driving time) after starting.

Further, in the above embodiment, the air compressor is taken as an example, but the present invention can be applied to other gas compressors as long as the gist is not deviated.

Further, in the above embodiment, a package type air compressor is taken as an example, and the gas tank 60 is arranged separately from the compressors 50 and 100, but the tank mount type compressor and the gas tank are integrated. It may be configured or may have a configuration in which a gas tank is built in the package.

Further, in the above embodiment, the refueling type compressor is taken as an example, but the refueling type compressor may be used to supply another liquid such as water to the compression operation chamber. Furthermore, it can be applied to a liquid-free gas compressor. In the case of the compressor body and the multi-stage configuration, location of Hokiben 14 is not limited to the high-pressure stage, the intermediate stage air may be a position where the air release.

1 ... Compressor body, 2 ... Electric motor, 3 ... Power converter, 4 ... Control device, 5 ... Suction throttle valve, 7 ... Suction port, 8 ... Suction filter, 10 ... Discharge piping, 11 ... Temperature sensor, 12 ... Gas Liquid separator, 13 ... secondary filter, 14 ... air release valve, 15 ... check valve, 16 ... air cooler, 17 ... pressure sensor, 20 ... oil piping, 21 ... oil cooler, 22 ... three-way valve, 23 ... pump, 24 ... Bypass piping, 25 ... Fan device, 30 ... Intake port, 32 ... Exhaust port, 40 ... Panel, 50/100 ... Compressor, 59 ... External piping, 60 ... Gas tank

Claims (3)

The compressor body that sucks in gas and discharges compressed gas, the pressure detection device that detects the discharge pressure of the compressed gas, the drive source of the compressor body, and the drive source can be used according to the detection value of the pressure detection device. A gas compressor having a control device for controlling shifting.
In the control device , when the discharge pressure is the set pressure P0, the rotation speed of the drive source becomes the full speed rotation speed, and when the discharge pressure rises from the set pressure P0 to the upper limit pressure P1, the rotation of the drive source The number decreases from the full speed rotation speed to the lower limit rotation speed, and the rotation speed of the drive source from the full speed rotation speed to the lower limit rotation speed is proportional to the discharge pressure from the set pressure P0 to the upper limit pressure P1. A gas compressor that controls the rotation speed of the drive source. The gas compressor according to claim 1.
A suction throttle valve for controlling the amount of intake gas is provided on the suction side of the compressor body.
Wherein the controller, when the discharge pressure is above the upper limit pressure P1, the closes the intake Komishibo Ri valve, the discharge pressure is higher than the set pressure P0, when less than the upper limit pressure P1, the A gas compressor that fully opens the suction throttle valve. The gas compressor according to claim 1.
An air release valve for releasing the compressed gas is provided on the downstream side of the compressor body.
Wherein the controller, when the discharge pressure is above the upper limit pressure P1, opens the air release valve, the discharge pressure is higher than the set pressure P0, when less than the upper limit pressure P1, the air release A gas compressor that closes the valve.

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