JP5046659B2 - air compressor - Google Patents

Description

  The present invention relates to an air compressor, and more particularly to an air compressor capable of controlling a stable pressure to a desired value.

  The operating state of the air compressor can be broadly classified into five cases of “start-up”, “full load operation”, “partial load operation”, “no load operation”, and “stop”. Patent Document 1 discloses an example in which each operation is performed by using an intake control valve (suction throttle valve) and moving a valve body provided in the intake control valve.

Japanese Patent Laid-Open No. 2001-90683

  An air compressor using a three-phase induction motor often has a structure for transmitting the rotation of the motor to the compressor body through a transmission belt or a gear or a coupling. For example, in the case of an oil-cooled screw compressor that uses a motor driven by the star delta system as a power source, at the time of `` start-up '', a suction throttle valve is used using compressed air generated by the rotation of the compressor body immediately after the start of operation. By closing and preventing further air intake, the load on the motor is kept light, and after a suitable time has elapsed after the motor has fully accelerated and switched to delta operation, the intake throttle valve is opened and air is taken in Start compression.

  When the compression is started, in the “full load operation”, the suction throttle valve takes in air in a fully opened state. “Partial load operation” is a so-called suction unload operation in which the suction throttle valve is gradually closed in accordance with the amount of compressed air used to reduce the amount of air taken into the compressor. The “no-load operation” is a so-called integral unload operation in which the suction throttle valve is fully closed and the air in the oil case is discharged into the atmosphere to reduce power.

  In addition, when “stopping”, the air inside the compressor body or air that has already been compressed flows back to the suction side together with oil, so it is necessary to close the suction throttle valve immediately after the stop signal is input There is.

  As described above, in the air compressor, opening and closing of the suction throttle valve must be controlled in accordance with each operating state.

  As a request in each state, at the time of “start-up”, it is necessary to close the capacity control valve and then reduce the pressure in the oil case as much as possible to lighten the load on the motor and start it more smoothly. On the other hand, in the integral unload operation during “no-load operation” (operation in which the suction throttle valve is fully closed and then vented), the pressure inside the oil case is better as much as possible from the viewpoint of power reduction. If the pressure is too low, there is a problem that the pressure difference between the suction side of the compressor body and the discharge side after compression becomes small.

  Due to such a problem, for example, in a screw compressor, the rotor in the compressor body may not rotate stably and may generate a large noise. Therefore, too much emphasis is placed on power reduction during “start-up” and “no-load operation”, and if the pressure in the oil case is too low, the operation noise of the compressor body increases. For this reason, it is difficult to realize a desirable oil case internal pressure at the time of “start-up” and “no-load operation” by a single air discharge path.

  In the past compressors, considering the above-mentioned phenomenon, the oil case internal pressure is compatible with both smooth start-up of the motor at "start-up" and noise suppression at integral unload operation at "no-load operation". In many cases, the air route was configured to drive.

  The configuration of Patent Document 1 includes, as a path from an oil case, in addition to a discharge flow path, a plurality of branch paths branched from now on, a path different from the discharge flow path, and a bypass flow path communicating between a plurality of spaces However, conventional compressors have a single oil case pressure that achieves both smooth start-up of the motor during `` start-up '' and noise suppression during integral unload operation during `` no-load operation ''. In general, the engine is operated by an air discharge route, and there is a problem that it is difficult to operate at an ideal oil case internal pressure at the time of “start-up” and “no-load operation”.

  The present invention has been made in view of the above problems, and an object thereof is to provide an air compressor that can be operated while suppressing noise in each state.

Specific embodiments of the present invention for achieving the above object are as follows.
In the first aspect, the compressor main body that compresses the air sucked from the suction throttle valve, the oil case that is positioned in the discharge path of the compressed air discharged from the compressor main body, and the air that branches off from the discharge path and air release path for performing, at the time of no-load operation and a structure and a control unit for controlling the small city of so that sectional area of the startup sectional area of the air release path.

  In the first aspect, it is preferable that the control device changes a cross-sectional area of the air discharge path by controlling an electromagnetic valve provided in the air discharge path.

In the second aspect, the compressor main body compresses the air sucked from the suction throttle valve, the oil case located in the discharge path of the compressed air discharged from the compressor main body, and the branch from the discharge path. a gas release passage for performing air release, and a solenoid valve and an orifice provided in the air release path, during no-load operation to a small city of so that sectional area of the startup sectional area of the air release path And a control device for controlling the electromagnetic valve.

  In any one of the above aspects, it is desirable that the air release path has a plurality of paths, and the control device controls opening and closing of one of the plurality of paths, and further, In order for the control device to control opening and closing of the one path, it is preferable to control opening and closing of an electromagnetic valve provided in the one path.

Further, as a third aspect, a compressor main body for compressing air sucked from the suction throttle valve, an oil case positioned in a discharge path for compressed air discharged from the compressor main body, and a branch from the discharge path. In an air compressor having an air release path for releasing air,
The air release path has a branch part and branches into a first air release path and a second air release path, and the second branch path is provided with an electromagnetic valve,
The electromagnetic valve is configured to include a control device that controls the air compressor to be opened when the air compressor is started and to be closed during no-load operation.

In any one of the first to third aspects, the control device includes:
It is desirable to control so that the pressure P in the oil case is higher than the upper limit pressure P _{0 in the} pressure region where the operation noise of the compressor body is large during no-load operation .

  According to the present invention, it is possible to provide an air compressor that can be operated while suppressing noise in each operation state.

  Embodiments of the present invention relate to means for controlling a stable pressure of an air compressor in each operating state to a desired value, and an air compressor with a stable pressure adjusting function will be described below with reference to the drawings.

  FIG. 1 is a diagram showing a system of an air compressor of the present embodiment. The power of the electric motor 2 that drives the compressor body 1 is transmitted by the transmission means 3. Examples of the transmission means 3 include a transmission belt, a gear, and a coupling. With this configuration, the air supplied into the compressor body 1 is compressed by being driven by the electric motor 2 via the transmission means 3. In the present embodiment, the starting method of the electric motor 2 will be described by taking the star delta method as an example, but the same applies to a direct insertion method and a soft start by an inverter.

  The air compressed by the compressor body 1 is sucked into the compressor body 1 via the suction filter 8 and the suction throttle valve 10. The air sucked into the compressor main body 1 is compressed to a predetermined pressure in the compressor main body 1, passes through the oil case 7, the heat exchanger 5, and the dehumidifier 6 located in the discharge path to the compressed air discharge port 9. Head to. Specifically, after being compressed by the compressor body 1 and removed through the oil case 7, the oil is cooled by the heat exchanger 5, further dehumidified by the dehumidifier 6, and then discharged from the compressed air discharge port 9. Is done.

  Next, the operation of the suction throttle valve 10 in each operation state of the compressor will be described with reference to FIG. FIG. 2 is a diagram showing a main part of the present embodiment. At the “start-up” of the air compressor, the compressed air generated in the compressor body 1 immediately after the start enters the operation chamber 13 of the suction throttle valve 10 through the oil case 7 and the discharge solenoid valve 11, and the piston 12 is Push to the air intake 15 side. A valve body 14 is attached to the tip of the piston 12 and moves to the left in the drawing (that is, the air intake 15 side) in accordance with the movement of the piston 12 and finally closes the air intake 15 of the suction throttle valve 10. .

  In this way, the air intake 15 is blocked by the valve body 14, so that the compressor body 1 continues to operate without taking in more air. The compressed air after entering the operation chamber 13 and pushing the piston 12 is connected to the primary side portion 17 of the suction throttle valve 10 from the operation chamber 13 through the orifice 16 (hereinafter referred to as an “air release route”). A), and two air discharges of the second air discharge path connected from the operation chamber 13 called the air discharge path B to the primary side portion 17 of the suction throttle valve 10 through the auxiliary electromagnetic valve 18 and the orifice 19. It is vented by the route.

  That is, the air release path in the present embodiment is a path that branches from the discharge path, passes through the air release electromagnetic valve 11 and the operation chamber 13, and extends from the air release paths A and B to the primary side portion 17. The primary side portion 17 of the suction throttle valve 10 is a portion corresponding to the air intake port 15, which is upstream of the valve body 14 on the air flow path and is at atmospheric pressure.

  At this time, since the compressor body 1 does not compress air as described above, new compressed air does not flow into the oil case 7 and the compressed air remaining inside passes through the air discharge paths A and B. The suction throttle valve 10 is discharged to the primary side portion 17. Therefore, the pressure inside the oil case 7 becomes low. Thereby, the load of the electric motor 2 which drives the compressor main body 1 is maintained in a light state, and it accelerates quickly and finishes starting.

  In “full load operation”, the compressed air entering the operation chamber 13 is shut off by switching the path in the discharge electromagnetic valve 11, and the action of pushing the piston 12 is lost. Instead, the operation of the compressor body 1 causes the secondary side portion 20 of the suction throttle valve 10 to become negative pressure, and the air intake 15 is opened by moving the valve body 14 to the right side in the figure, so that air enters the compressor body 1. Captured and compressed. The secondary side portion 20 of the suction throttle valve 10 is a portion closer to the compressor body 1 than the valve body 14 on the air flow path, and is a portion downstream of the primary side portion 17 described above.

  The suction unload operation during the “partial load operation” is an operation when the amount of compressed air used is reduced. At this time, the pressure inside the oil case 7 increases due to excess air. When the pressure rises to a certain value, the pressure adjustment valve 21 starts to open, and compressed air is supplied to the operation chamber 13 of the suction throttle valve 10. As a result, the piston 12 is gradually pushed to the left in the figure, and the distance between the valve body 14 attached to the tip of the piston 12 and the air intake 15 is reduced, so that the air taken into the compressor body 1 gradually decreases, and the power Is reduced. At this time, the path connected to the operation chamber 13 via the air release electromagnetic valve 11 is blocked, and the compressed air inside the oil case 7 is not supplied to the operation chamber 13. Therefore, the force that pushes the piston 12 is limited, and the air intake 15 is not closed by the valve body 14.

  In the integral unload operation during “no load operation”, a part of the air compressed by the compressor main body 1 enters the operation chamber 13 of the suction throttle valve 10 as in the “start-up” operation, and the piston 12 enters the left side in the figure. The air intake 15 is closed by the valve body 14 at the tip of the piston 12. The compressed air after entering the operation chamber 13 and moving the piston 12 is discharged to the primary side portion 17 of the suction throttle valve 10 via the discharge path A. However, at this time, unlike the “start-up”, the control device 4 performs control so as to block the air release path B. Specifically, the internal passage of the auxiliary electromagnetic valve 18 installed in the middle of the air release path B is switched, and the control device 4 controls the auxiliary electromagnetic valve 18 so that the air release path B is blocked.

  Therefore, the air release in the integral unload operation during the “no load operation” is performed only through the air release path A. In this way, the control device 4 controls the auxiliary electromagnetic valve 18 to reduce the air discharge amount, so that the pressure in the oil case 7 is kept high. As a result, the operation of the compressor body 1 is stabilized, and the conditions for generating noise and the like are eased.

  In other words, it is possible to achieve stable operation and noise suppression of the compressor body 1 by controlling the cross-sectional area of the air release path so as to change between startup and no-load operation. As a specific form for that purpose, the cross-sectional area of the air release path is changed by controlling the electromagnetic valve 18 provided in the air release path.

  FIG. 3 is a diagram showing the relationship between the operation sound of the compressor main body and the oil case internal pressure in the screw compressor during the integral unload operation, where the vertical axis represents the compressor main body operation sound S and the horizontal axis represents the oil case. The internal pressure P is shown respectively.

When the pressure in the oil case is high (in FIG. 3, for example, P = P ₁ ), the pressure difference between the suction side of the compressor body and the discharge side after compression is large. At this time, the compressor rotor rotates stably, and the operation sound is suppressed to a low level. However, when the pressure P in the oil case is increasing gas release amount gradually decreases, as the boundary a certain pressure P _0, the operating noise S rapidly increases. In the case where the oil case pressure is located in a region below P ₀ indicated by the hatched portion in FIG. 3, for example, at P = P ₂ , the pressure difference between the compressor suction side and the discharge side becomes small, and the rotor Stable rotation cannot be realized, and excessive noise is generated from the compressor body.

  That is, the control device 4 according to the present embodiment performs control so that the pressure in the oil case does not enter the excessive noise generation region indicated by the oblique lines in FIG. 3 during the integral unload operation. As a specific configuration for this purpose, a plurality of systems for releasing compressed air from the oil case 7 are provided (air release paths A and B), and the opening and closing of these paths is controlled according to each operation state. Thus, the pressure difference between the compressor suction side and the discharge side is suppressed from becoming small.

  In the present embodiment, the specific configuration is not particularly limited as long as the control is performed so that the pressure in the oil case 7 does not enter the excessive noise generation region. Therefore, a sensor for monitoring the pressure in the oil case may be provided, and the discharge electromagnetic valve 11 and the auxiliary electromagnetic valve 18 may be controlled in a pattern set in advance depending on the operation state.

  According to the embodiment described above, since the stable pressure (pressure in the oil case) in each operation state of the compressor can be individually controlled, the motor can be started more smoothly and the integral unload operation during no-load operation can be performed. It is possible to achieve both suppression of compressor main body noise. Moreover, from the viewpoint of power reduction, since it is better that the stable pressure during no-load operation is low, there is an effect that a lower limit pressure at which main body noise is not generated can be set.

  At the time of “stop”, the compressed air is supplied to the operation chamber 13 and the air intake 15 is closed by the valve body 14 in the same manner as at the time of “start-up”. Prevent leakage of compressed air and oil. At this time, the air discharge paths A and B are both in a state where a path connected to the primary side 17 of the suction throttle valve 10 is secured, and the compressed air inside the oil case 7 is quickly discharged.

  Note that the operations of the air release electromagnetic valve 11 and the auxiliary electromagnetic valve 18 that control the opening and closing of the air release paths A and B are controlled by the control device 4 of the compressor. It controls the parts necessary for machine operation.

The figure which shows the system | strain of the air compressor of a present Example. The figure which shows the principal part of a present Example. The figure which shows the relationship between the driving sound of a compressor main body, and the oil case internal pressure.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Compressor main body, 2 ... Electric motor, 3 ... Transmission means, 4 ... Control apparatus, 5 ... Heat exchanger, 6 ... Dehumidifier, 7 ... Oil case, 8 ... Suction filter, 9 ... Compressed air discharge port, 10 DESCRIPTION OF SYMBOLS ... Suction throttle valve, 11 ... Exhaust solenoid valve, 12 ... Piston, 13 ... Operation chamber, 14 ... Valve body, 15 ... Air intake, 16 ... Orifice, 17 ... Primary part, 18 ... Auxiliary solenoid valve, 19 ... Orifice, 20 ... secondary side part, 21 ... pressure regulating valve, A ... air release path A, B ... air release path B.

Claims (7)

A compressor body that compresses air sucked from the suction throttle valve, an oil case that is positioned in a discharge path of compressed air that is discharged from the compressor body, and an air discharge path that diverges from the discharge path and discharges air , no-load air compressor and a control device for controlling the small city of so that the cross-sectional area than the cross-sectional area of the startup of the gas release path during operation.   The air compressor according to claim 1, wherein the control device changes a cross-sectional area of the air discharge path by controlling an electromagnetic valve provided in the air discharge path. A compressor body that compresses air sucked from the suction throttle valve, an oil case that is positioned in a discharge path of compressed air that is discharged from the compressor body, and an air discharge path that diverges from the discharge path and discharges air the air release is provided in the path and an electromagnetic valve and the orifice, the control device at the time of no-load operation for controlling the solenoid valve than in the small city of so that the cross-sectional area of the startup sectional area of the air release path And an air compressor.   The air compressor according to any one of claims 1 to 3, wherein the air discharge path has a plurality of paths, and the control device controls opening and closing of one of the plurality of paths. .   5. The air compressor according to claim 4, wherein the control device controls opening and closing of an electromagnetic valve provided in the one path in order to control opening and closing of the one path. A compressor body that compresses air sucked from the suction throttle valve, an oil case that is positioned in a discharge path of compressed air that is discharged from the compressor body, and an air discharge path that diverges from the discharge path and discharges air In an air compressor with
The air release path has a branching portion and branches into a first air release path and a second air release path, and the second branch path is provided with an electromagnetic valve,
The air compressor provided with the control apparatus which controls that the said solenoid valve opens at the time of starting of the said air compressor, and closes at the time of a no-load driving | operation. The controller is
The pressure P in the oil case is controlled so as to be higher than the upper limit pressure P _{0 in the} pressure region where the operation noise of the compressor body becomes large during no-load operation. The air compressor according to any one of 6.

Images