JPH0320600B2 - - Google Patents

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to an oil supply amount control device suitable for an oil-free screw compressor that does not supply oil to a compression chamber and is equipped with a non-contact type shaft seal member. .

[Conventional technology]

As a conventional device of this kind, for example,
Publication No. 2481 describes how to reduce the amount of oil supplied to the compression chamber during no-load operation to reduce the amount of discharged compressed gas in a so-called oil-cooled screw compressor that supplies oil to the compression chamber to generate compressed gas. This is disclosed.

[Problem that the invention seeks to solve]

The conventional device described above reduces the amount of oil supplied to the compression chamber when there is no load, and there is no mention of the amount of oil supplied to bearings, etc. other than the compression chamber. It cannot be applied to the following problems in free screw compressors.

That is, in an oil-free screw compressor, the shaft seal member is composed of a carbon seal of a gas shaft sealing device and a visco seal of a bearing oil draining shaft sealing device. During operation, static pressure is generated in the visco seal due to the viscous effect of air due to the rotation of the rotor, which prevents waste oil from the rotor shaft bearing from entering the compression chamber. During rated operation (for example, at a discharge pressure of 7 atm), high-pressure air is generated especially in the shaft seal member on the discharge side, so the effect of preventing intrusion of waste oil becomes even greater.

On the other hand, when there is no load, the pressure difference acting on the shaft seal member on the suction side increases because the suction pressure in the compression chamber becomes negative pressure due to the intake blockage of the suction unloader, and the pressure difference that exceeds the static pressure of the visco seal increases. If this occurs, the possibility that waste oil from the bearing will enter the compression chamber increases. Since a certain amount of positive pressure acts on the shaft seal member on the discharge side even when there is no load, there is no risk of oil entering the compression chamber.

Furthermore, even if the power to the motor for rotating the rotor is turned off, the compressor continues to rotate for a certain amount of time due to inertia. At this time, the rotational speed of the rotor rapidly decreases, and the Visco seal is no longer able to generate static pressure. However, since the oil pump for oil supply is directly driven by a bull gear, there is a risk that oil will be supplied to the bearing as the oil pump rotates, passing through both the suction and discharge side shaft seal members and entering the compression chamber. be.

Furthermore, when starting up the compressor, a control sequence is adopted in which the suction unloader is kept close to fully closed in order to reduce the starting load.
The same danger as when no load occurs.

The purpose of the present invention is to prevent bearing waste oil from entering the compression chamber at low speeds when starting, stopping, and under no load, and to prevent the risk of oil from entering the compressed air.
An object of the present invention is to provide a highly reliable oil supply amount control device for an oil-free screw compressor that can supply clean air with a high degree of cleanliness.

[Means to solve the problem]

The above purpose is to provide a compressor body that is equipped with a male rotor and a threaded rotor having mutually parallel axes, a non-contact type shaft sealing device, and a pinion that is attached to one end of the male rotor that meshes with the pinion. An oil-free screw compressor is provided with a speed increaser including a bull gear, and an oil pump connected to and driven by the shaft of the bull gear to supply oil to a bearing portion of a compressor body, and a rotor rotation speed detection means is provided. and a continuous oil amount adjustment means that is interlocked with the detection signal of the rotation speed detection means and an ON-OFF type oil amount adjustment means that is interlocked with the load condition of the compressor, in the middle of the oil guide pipe of the oil pump. When the rotation speed increases or decreases during startup and stop, the amount of oil supplied to the compressor body is increased or decreased in accordance with the rotation speed using the continuous oil amount adjustment means, and when there is no load, the oil amount adjustment is performed using the ON-OFF method. This is achieved by reducing the amount of oil supplied to the compressor body using means and controlling the two oil amount adjusting means independently of each other.

[Effect]

With the above configuration, at the rated rotation speed, the load acting on the bearing is reduced when there is no load, and the amount of heat generated is also reduced, so it is sufficient to supply less oil than when under full load. By turning off the adjustment means, the amount of oil supplied can be reduced. In addition, when the compressor starts and stops, there is no load on the compressor, so the ON-OFF type oil amount adjustment means is turned OFF, and the heat generation of the bearing changes with the 1.5 to 2 power of the rotation speed. Therefore, the continuous oil amount adjustment means can increase or decrease the amount of oil supplied in accordance with the increase or decrease in the rotational speed, and the amount of oil supplied can be maintained at the minimum necessary amount.

In addition, the ON-OFF type oil amount adjustment means is controlled only in response to the load, and the continuous oil amount adjustment means is controlled only in response to the rotation speed of the compressor, so each can be controlled independently, and the control system This simplifies the process.

〔Example〕

An embodiment of the present invention will be described below with reference to FIGS. 1 and 2. FIG. 1 is a block diagram of a single-stage oil-free screw compressor as a unit.

The compressor main body 20 is attached to a gear casing 50, and a suction unloader 90 is disposed above it. The rotor housed in the casing of the compressor main body 20 is driven by the motor 60.
It is driven via a motor sheave 60a, a V-belt 60b, a V-pulley 50a, and a bull gear 50b that is housed in the gear casing 50 and constitutes a speed increaser, and a pinion gear 11 that meshes with the bull gear 50b. FIG. 2 shows the structure of the compressor main body 20 mentioned above.

A male rotor 1 and a female rotor 2 are housed in a casing in a meshed state. The casings are suction casing 4, discharge casing 3, and end cover 5.
It becomes more. The discharge casing 3 accommodates both the rotors 1 and 2, and a suction casing 4 is disposed at the suction side end of the discharge casing 3. The suction side shaft 1 s and the discharge side shaft 1 d of the male rotor 1 and the suction side shaft 2 s and the discharge side shaft 2 d of the female rotor 2 are inserted into a shaft seal member 8 disposed in the shaft penetrating portion of the casing. Furthermore, both rotors 1 and 2 have a radial load supported by a bearing 6 and a thrust load supported by a bearing 7, respectively. A pair of timing gears 9 and 10 are attached to the ends of the discharge shafts 1d and 2d of the male rotor 1 and the female rotor 2 in a meshing state, and are arranged so that the two rotors rotate without contacting each other. There is.
Further, the aforementioned pinion 11 is attached to the shaft end of the suction side shaft 1s of the male rotor 1, and is driven by a bull gear 50b. When the rotational force is transmitted to the pinion 11, the pair of male rotor 1 and female rotor 2 rotate synchronously while maintaining a small gap by the timing gears 9 and 10. As a result, external air is sucked into the space formed by the tooth grooves of both rotors 1 and 2 through the suction unloader 90, and as both rotors 1 and 2 rotate, the volume of this space is gradually reduced, and the enclosing The device becomes compressed air,
It is discharged from a discharge port (not shown). This discharged air is precooled by a precooler 30 via a pressure impulse pipe 20a, and then is passed through a pressure impulse pipe 30a and a check valve 30b.
It is cooled down to room temperature by an aftercooler 40, flows out of the unit, and is used for various purposes. A gear 70a is disposed in mesh with a gear 50c disposed coaxially with the aforementioned bull gear 50b, and an oil pump 70 is connected to the shaft of this gear 70a for deceleration driving. An oil guide pipe 70c from the oil pump 70 is connected to a branch pipe 70d having a control valve 130 with a variable flow path area, which is a means for continuously adjusting the amount of oil supplied.
A branch pipe 70e having a solenoid valve 140, which is an ON-OFF type oil amount adjustment means, is branched, and then the oil guide pipe 1
50 and communicates with the inside of the gear casing 50 described above.

On the other hand, a sensor 110 for detecting the number of rotations of the pinion 11 is disposed above the gear casing.
This sensor 110 has lead wires 110a, 120
It is connected to the aforementioned control valve 130 via a converter 120 at point a.

The control valve 130 is controlled to be fully closed when the pinion 11 is under a certain rotational speed or higher, at full load and under no load, and when the motor 60 is turned off and the rotational speed of the pinion 11 begins to decrease, its rotation is closed. The opening degree is increased according to the speed, and it is controlled so that it is fully open when it is completely stopped. Further, the electromagnetic valve 140 is open when there is no load and is closed when the load is full. Further, the pinion 11 is in an open state when the rotational speed is below the rated speed.

Therefore, at startup, the oil pump 70
Most of the amount of oil supplied from the bearings is bypassed to the gear casing 50 via the control valve 130 and the solenoid valve 140, so that only the minimum necessary amount of oil is supplied to the bearings and the like. As the rotational speed of the pinion 11 increases, the opening degree of the control valve 130 decreases in proportion to the speed, and the amount of oil supplied to the bearings etc. gradually increases, and when the rated operation begins and the full load is reached, the control valve 130 opens. 130 is fully closed, and the solenoid valve 140 is closed, resulting in 100% oil supply.

When the compressor is under no load, the solenoid valve 140 opens and the amount of oil supplied decreases by the amount bypassed by the gear casing 50.

Furthermore, when the power to the motor 60 is turned off, the solenoid valve 140 opens and the opening degree of the control valve 130 increases as the rotation speed of the pinion 11 increases, so the amount of oil supplied decreases rapidly, and when the pinion 11 completely stops, the amount of oil supplied decreases. The quantity also becomes zero.

As mentioned above, when there is no load, the pressure difference acting on the shaft seal member on the suction side increases, and even if it exceeds the static pressure of the Visco seal, the amount of oil supplied to the bearing also decreases, so there is a risk of oil getting into the compression chamber. It can prevent sex.
Furthermore, even during the time when static pressure is not generated in the visco seal due to insufficient rotational speed of the rotor at startup, the amount of oil supplied is smaller than when the engine is fully loaded, so it is possible to prevent oil from entering the compression chamber. Furthermore, the same effect is obtained when the compressor is stopped as when it is started, and it is possible to prevent oil from entering the compression chamber.

〔Effect of the invention〕

As described above, according to the present invention, it is possible to prevent waste oil from the bearing from entering the compression chamber during startup, at low speeds when stopping, and when there is no load, thereby preventing the risk of oil from entering the compressed air. There is an effect.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of the present invention applied to a single-stage oil-free screw compressor, and FIG. 2 is a structural diagram of the compressor main body in FIG. 1. 20...Compressor body, 30...Blowout precooler, 40...Aftercooler, 50...Gear casing, 70...Oil pump, 70c...Oil guide pipe, 7
0d, 70e...branch pipe, 110...sensor, 1
30...Control valve, 140...Solenoid valve.

Claims (1)

[Scope of Claims] 1. A compressor body comprising a male rotor and a female rotor having mutually parallel axes and a non-contact shaft sealing device, a pinion attached to the male rotor and one end thereof, and a compressor body having a non-contact type shaft sealing device; An oil-free screw compressor comprising a speed increaser including a meshing bull gear, and an oil pump connected to and driven by a shaft of the bull gear to supply oil to a bearing portion of a compressor body, wherein the compressor includes: A rotor rotation speed detection means is provided, and a continuous oil amount adjustment means interlocked with the detection signal of the rotation speed detection means is provided in the middle of the oil guide pipe of the oil pump, and an ON-OFF type that is interlocked with the load condition of the compressor. An oil amount adjusting means is provided, and the continuous oil amount adjusting means is used when increasing and decreasing the rotation speed at startup and stop.
The amount of oil supplied to the compressor body is increased or decreased in accordance with the rotation speed, and when there is no load, the amount of oil supplied to the compressor body is reduced using the ON-OFF type oil amount adjustment means, and the two oil amount adjustment means are An oil supply amount control device for an oil-free screw compressor, characterized in that the oil supply amount is controlled independently of each other.