JPH05106578A - Warming-up control method for screw type dry vacuum pump - Google Patents

Abstract

PURPOSE:To shorten the time for warming up a screw type dry vacuum pump, when it is started in the condition not evacuated, and reduce the power for warmup operation by throttling the discharge side or feeding back the discharged fluid via a shortcircuit passing the vacuum pump. CONSTITUTION:A chamber 2 is connected through a suction piping 3, which is fitted with a main valve 5, with the suction side of a screw type dry vacuum pump 1, while a discharge piping 4 is connected with its discharge side, to form a vacuum system, in which a throttle valve 6 is mounted on the discharge piping 42. In case this vacuum pump 1 is started in the condition not evacuated, it is started with the valve 6 throttled. Thereby the discharge pressure is applied to the vacuum pump 1, and its rotor, easing, etc., are warmed with the compression heat thus generated, and the warming-up is completed quickly. Otherwise a bypass piping is arranged so as to detour by the vacuum pump, and a bypass valve installed on the piping is opened, and the discharged fluid is circulated via the vacuum pump.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a warm-up operation control method for a screw type dry vacuum pump used in a vacuum system of a semiconductor manufacturing apparatus.

[0002]

2. Description of the Related Art FIG. 4 is a side sectional view showing a structural example of a screw type dry vacuum pump of this type. The screw type dry vacuum pump has a main casing 11 and a discharge casing 12.
In the space formed by and, the male rotor 17a and the female rotor 1
7b are rotatably supported by bearings 15a and 15b, respectively, and the bearing 15 is supported by shaft sealing mechanisms 16a and 16b.
It is sealed from the lubricating oils a and 15b. Male rotor 1
The shaft of 7a is directly connected to the shaft of the electric motor 22, and the female rotor 17b
Is rotated by the timing gears 20 and 20 with a slight gap from the male rotor 17a.

The gas sucked from the suction port 18a passes through the suction port 18b, is sucked into the tooth space formed by the inner wall of the rotor of the main casing 11 and the male and female rotors 17a and 17b, and is discharged through the compression process. The liquid is discharged from the discharge port 19a via 19b. Reference numeral 13 in the figure is a gear cover, and 14 is an electric motor casing.

[0004]

In the screw type dry vacuum pump having the above structure, the discharge temperature is high during evacuation, and the male rotor 17a and the female rotor 17b and the rotor and the main casing 11 are prevented from coming into contact with each other in that state. Since the gap is set, the ultimate vacuum is low in the cooling state of the pump, and it is necessary to perform warm-up operation for a long time to obtain a predetermined ultimate vacuum, which further increases the power during warm-up operation. There was a problem.

The present invention has been made in view of the above points, eliminates the above problems, and shortens the warm-up operation time,
Another object of the present invention is to provide a warm-up operation control method for a screw type dry vacuum pump, which can reduce power consumption during warm-up operation.

[0006]

In order to solve the above-mentioned problems, the present invention satisfies one of the following conditions or two or more conditions from the non-evacuated state of a screw type dry vacuum pump. The feature is that warm-up operation is performed in a closed state. A throttle valve is provided on the discharge side of the screw type dry vacuum pump, and the throttle valve is throttled. The screw type dry vacuum pump is provided with a bypass passage connecting the discharge side and the suction side, and the valve provided in the bypass passage is opened. The flow rate of the cooling fluid for cooling the screw type dry vacuum pump body is reduced, stopped, or partially stopped. A large amount of purge gas is made to flow into the pump from the suction side of the screw type dry vacuum pump.

Also, the suction pressure of the screw pump or the temperature of the pump casing is monitored to reduce or stop the flow rate of the cooling fluid for controlling the throttle valve, controlling the valve provided in the bypass passage, or partially It is characterized in that the purge gas flow rate control for stopping the control is automatically performed.

[0008]

By performing the warm-up operation of the screw type dry vacuum pump as described above, the following actions can be obtained. When the throttle valve provided on the discharge side of the pump is throttled, the discharge pressure is applied to the pump, and the heat of compression accelerates warming up. When the valve provided in the bypass passage is opened, the discharged fluid returns to the suction side of the pump and circulates through the bypass passage. By repeating this circulation of the fluid, the temperature of the fluid gradually rises and the warming up is accelerated. When the flow rate of the cooling fluid is reduced, stopped, or partially stopped, heat dissipation is suppressed particularly in the casing of the rotor portion, so that warming up is accelerated. When a large amount of purge gas is flown into the vacuum pump from the suction side of, the warm-up is accelerated by the heat of compression of the purge gas.

Also, by monitoring the pump suction pressure or the pump casing temperature and automatically performing the above-mentioned control, it is possible to prevent the pump casing, the rotor, etc. from becoming too hot. Also, by controlling the number of revolutions, the power during warm-up operation can be reduced.

[0010]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a diagram showing a configuration example of a vacuum system used in a semiconductor manufacturing process or the like to which the warming-up operation control method of the present invention is applied. In FIG. 1, 1 is a screw type dry vacuum pump, a chamber 2 is connected to the suction side of the screw type dry vacuum pump 1 through a suction pipe 3, and a discharge pipe 4 is connected to the discharge side. The suction pipe 3 is provided with a main valve 5, and the discharge pipe 4 is provided with a throttle valve 6.

In the vacuum system having the structure shown in FIG. 1, when the screw type dry vacuum pump 1 is started from a state in which the vacuum is not evacuated, first the throttle valve 6 of the discharge pipe 4 is throttled and then the vacuum pump 1 is started. To do. As a result, a discharge pressure is applied to the vacuum pump 1, and the rotor of the vacuum pump, the casing, and the like are warmed by the heat of compression, which accelerates warming up.

FIG. 2 is a diagram showing another structural example of a vacuum system to which the warming-up operation control method of the present invention is applied. As shown in FIG. 2, in the present vacuum system, a bypass pipe 7 that connects the suction side and the discharge side of the screw type dry vacuum pump 1 is provided, and the bypass pipe 7 is provided with a bypass valve 8.

In the vacuum system having the structure shown in FIG. 2, when the screw type dry vacuum pump 1 is started from a state where the vacuum is not evacuated, the bypass valve 8 is opened to start the vacuum pump 1. As a result, the fluid discharged from the vacuum pump 1 returns to the suction side through the bypass pipe 7 and circulates. By repeating this circulation, the temperature of the fluid gradually rises and the warm-up is accelerated. In this vacuum system, the bypass pipe 7 of the screw-type dry vacuum pump 1 is provided, but it goes without saying that the bypass passage may be provided inside the vacuum pump 1 and the bypass valve may be provided in the bypass passage. .. In any case, it suffices that the fluid be circulated in the main body of the vacuum pump 1.

FIG. 3 is a diagram showing another configuration example of a vacuum system to which the warming-up operation control method of the present invention is applied. As shown in FIG. 2, in this vacuum system, a purge gas supply pipe 9 is connected to the suction pipe 3.

In the vacuum system having the structure shown in FIG. 3, when the screw type dry vacuum pump 1 is started from a state where the vacuum is not evacuated, the screw type dry vacuum pump 1 is supplied from the purge gas source through the purge gas supply pipe 9.
By injecting the purge gas into the inside, warm-up is accelerated by the heat of compression of the purge gas.

As a method for accelerating the warm air, for example, in the vacuum pump having the structure shown in FIG.
1 cooling jacket 11a and the discharge casing 12 cooling jacket 12a flow rate of cooling water is reduced or stopped or partially stopped (for example, the main casing 1).
Stop cooling water flowing to the cooling jacket 11a of No. 1). As a result, there is also a method in which heat release from the main casing 11 and the discharge casing 12 is suppressed to accelerate warming up.

In the above embodiment, the method for accelerating the warm air is shown individually. However, these methods are not used individually, but the configuration examples of FIGS. 1 to 3 and the flow rate of the cooling water are reduced or stopped. Alternatively, there is a method of combining two or more methods of partially stopping.

Further, the throttle control of the throttle valve 6 of FIG. 1, the opening / closing control of the bypass valve 8 of FIG. 2, the supply control of the purge gas from the purge gas supply pipe 9 of FIG. 3, and the cooling jackets 11a and 12a of FIG. The control for reducing, stopping, or partially stopping the flow rate of the cooling water is performed by monitoring the suction pressure of the vacuum pump 1 or the temperature of the pump casing and automatically performing the control so that the pump casing, the rotor, and the like have a higher temperature than necessary. It is possible to accelerate warming up while preventing from becoming.

Further, in the warm-up operation in which the screw type dry vacuum pump 1 is started from the state where the vacuum is not evacuated, the power is reduced by lowering the rotation number of the screw type dry vacuum pump 1 as compared with the case of vacuuming. Can be made Also, screw type dry vacuum pump 1
It is also possible to monitor the suction pressure or the temperature of the pump casing and automatically control the rotation speed of the vacuum pump.

[0020]

As described above, according to the present invention, it is possible to provide a warm-up operation control method for a screw type dry vacuum pump which can shorten the warm-up operation time and reduce the power during the warm-up operation.

[Brief description of drawings]

FIG. 1 is a diagram showing a configuration example of a vacuum system to which a warming-up operation control method of the present invention is applied.

FIG. 2 is a diagram showing another configuration example of a vacuum system to which the warming-up operation control method of the present invention is applied.

FIG. 3 is a diagram showing another configuration example of a vacuum system to which the warming-up operation control method of the present invention is applied.

FIG. 4 is a side sectional view showing a structural example of a screw type dry vacuum pump.

[Explanation of symbols]

 1 Screw type dry vacuum pump 2 Chamber 3 Suction pipe 4 Discharge pipe 5 Main valve 6 Throttle valve 7 Bypass pipe 8 Bypass valve 9 Purge gas supply pipe

Claims (5)

[Claims] 1. A warm-up operation of a screw-type dry vacuum pump, characterized in that warm-up operation is performed in a state in which the screw-type dry vacuum pump is not evacuated and satisfies any one of the following conditions. Operation control method. A throttle valve is provided on the discharge side of the screw type dry vacuum pump, and the throttle valve is throttled. A bypass passage connecting the discharge side and the suction side is provided in the screw type dry vacuum pump, and a valve provided in the bypass passage is opened. The flow rate of the cooling fluid for cooling the screw type dry vacuum pump body is reduced, stopped, or partially stopped. A large amount of purge gas is flown into the pump from the suction side of the screw type dry vacuum pump. 2. A warm-up operation control method for a screw type dry vacuum pump, characterized in that any two or more of the above conditions are combined and the warm-up operation is performed in a state where the conditions are satisfied. 3. The method for controlling the warm-up operation of the screw type dry vacuum pump according to claim 1 or 2, wherein the suction pressure of the screw type dry vacuum pump or the temperature of the pump casing is monitored, and A warm-up operation control method for a screw type dry vacuum pump, which is characterized by automatically controlling two or more conditions. 4. The claim 1, the claim 2, or the claim 3.
In the method for controlling warm-up operation of the screw type dry vacuum pump, the method for controlling warm-up operation of the screw type dry vacuum pump is characterized in that the pump rotational speed is lower than that at the time of vacuuming. 5. The method for controlling the warm-up operation of the screw type dry vacuum pump according to claim 4, wherein the suction pressure of the screw pump or the temperature of the pump casing is monitored, and the rotational speed control of the pump is automatically performed. A method for controlling warm-up operation of a characteristic screw type dry vacuum pump.