JPH02241999A - Driving device for dry vacuum pump - Google Patents

Abstract

PURPOSE:To secure starting of a driving device even if matter-sticking gas is exhausted in a pump by using ac power supply and high-frequency inverter for the driving power supply of a vacuum pump, and driving multiple electromagnetic switches for switching-over means of both power supplies by timers. CONSTITUTION:An alternating current electric motor IM for comprizing an inverter 7 and a driving unit 3 is connected to electromagnetic switches 13, 16, and 17, and to a coil 14. To turn on and off the electromagnetic switches 13, 16, and 17 in sequential order, setting times for a relay X and a timer relay T1 (b) contact, timer relays T2 and T3 for (a) contact, namely setting times for relays T1 to T3 are predetermined at t1 to t3, respectively. It the setting times t1 to t3 are determined in relation t1<t2<t3, when the motor is started, the first electromagnetic switch 13 is turned on, the first electromagnetic switch 13 is turned off, the second electromagnetic switch 16 is turned on, and the third electromagnetic switch 17 is turned on. Thus, after the ac motor IM is started by an ac power supply 8 through the coil 14, it is stopped once and, after switching over it to the inverter 7, it can be driven again.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a vacuum pump whose exhaust port is set to atmospheric pressure, and particularly relates to a vacuum pump drive device suitable for use as an exhaust pump in semiconductor manufacturing equipment. .

[Prior Art] In a conventional vacuum pump drive device, for example, as shown in FIG. 6, a vacuum pump 1 is divided into a pump section 2 and a drive section 3, and the drive section 3 is generally an induction motor or a synchronous motor. AC motors such as are used. The pump part 2 is
A rotating rotor (not shown) and a stationary stator (not shown) are built into a casing 6 having an intake port 4 and an exhaust port 5, and the gas sucked in from the intake port 4 is compressed and exhausted. It is discharged from port 4 to atmospheric pressure. Further, the pump section 2 has no liquid such as oil or water in its gas passage section, and such a pump is generally called a dry vacuum pump.

Various types of pump parts are used for the dry vacuum pump. For example, as a high-speed rotation type,
Turbo and screw types are used. Among these, the turbo type has the major characteristics of compactness and low temperature, and its details are disclosed in, for example, Japanese Patent Application Laid-Open No. 61-247899.
It is proposed in the Publication No.

Conventionally, such a high-speed rotation type dry vacuum pump uses a high-frequency motor for the drive section 3 as shown in FIG. Generally, the pump is rotated at high speed via the drive section 3 using high frequency waves generated by an inverter.

The reason why the inverter 7 is conventionally used as described above is that high speed rotation can be maintained, and the drive unit 3 can be made smaller and have lower noise.

[Problems to be Solved by the Invention] The above-mentioned conventional technology does not cause any problems when discharging gases such as air and nitrogen gas. There are pumps that handle condensable or sublimable gases, and in some cases, as in the turbo vacuum pump shown in FIG. 7, when the rotor 9 is rotating at high speed while maintaining a gap with the stator 10, Since the outer surface of 10 is cooled, substances that tend to adhere may adhere to the position indicated by reference numeral 11.

The above-mentioned substance fixes the rotor 9 when the vacuum pump is stopped, so even if an attempt is made to rotate the rotor 9 using the inverter, there has been a problem in that the rotor 9 cannot be started with the small starting torque provided by the inverter.

SUMMARY OF THE INVENTION An object of the present invention is to provide a dry vacuum pump driving device that can reliably start a vacuum pump even when discharging gas that may cause substances to adhere to the inside of the vacuum pump.

[Means for Solving the Problems] In order to achieve the above object, a dry vacuum pump drive device of the present invention includes an AC power source and a high-frequency inverter as a drive power source for an AC motor that drives the vacuum pump, and The power source and the high frequency inverter are configured to be switchable by a switching means.

Further, the switching means is composed of a plurality of electromagnetic switches in order to simplify the structure.

Further, in order to automate the switching means, a plurality of electromagnetic switches are each driven by a timer.

[Function] When driven by a high frequency power source using an inverter, it is possible to obtain a steady rotation speed of 10,000 revolutions per minute or more, so the rotating part of the vacuum pump can be downsized.

On the other hand, when a vacuum pump is directly driven by an AC power source such as a regular 501 (z or 607), the torque at startup is large, but the rotation speed at steady state is 3,000 to 3 per minute.
It stays at 600 rpm.

As mentioned above, if the rotating part is stuck due to deposits inside the vacuum pump, if the vacuum pump is directly driven by a normal AC power source, the large driving torque will remove the deposits and allow the vacuum pump to rotate.

Therefore, the present invention drives the vacuum pump with a normal AC power source to make it rotatable, then switches from the normal AC power source to a high frequency power source using an inverter, and uses the inverter to rotate the vacuum pump at high speed. .

Therefore, it is possible to downsize the vacuum pump and to start the vacuum pump reliably.

[Example] Hereinafter, a description will be given of FIG. 1 showing a drive device for a dry vacuum pump which is an example of the present invention.

As shown in FIG. 1, a drive device 12 is installed between the drive section 3 of the vacuum pump 1 and the AC power source 8.

The drive device 12 includes a circuit 15 that connects an AC power source 8 to the drive section 3 via a first switch 13 and a coil 14, and a second switch 16 and a third switch 17 on both sides of the AC power source 8. The circuit 18 is connected in parallel with the circuit 18 connected to the drive section 3 via the inverter 7.

Note that the first switch 12. An electromagnetic switch is used for the second switch 15 and the third switch 16, and when the coil 13 directly drives the drive unit 3 by the AC power supply 8,
It is installed to prevent the steady current from becoming too large, and its size is determined based on the rating of the drive unit 3.

Next, the operation will be explained.

When starting the vacuum pump 1, first turn off the second switch 15 and the third switch 16, and then turn on the first switch 12. The vacuum pump 1 rotates at 3000 revolutions per minute or 360 revolutions per minute.
Driven at 0 rotations.

At this time, even if the substance attached to the inside of the vacuum pump 1 is attached at the position indicated by the reference numeral 11 in FIG. Start.

When the rotor 9 starts rotating in this way.

After the first switch 12 is turned OFF to temporarily stop driving the drive unit 3, the second switch 15 and the third switch 1 are turned off.
6 is turned on, the vacuum pump 1 gradually increases its rotation speed due to the high frequency power generated by the inverter 7 and reaches a steady high speed rotation.

The torque at startup is proportional to the square of the applied voltage.

When driven by an inverter, the applied voltage at startup is low, but if this is set to 20V, for example.

Applied voltage 2 when driving part 3 directly with AC power supply 8
Since it is 1/10 of 00 V, its driving torque is 1
/100. Therefore, when the rotor 9 becomes stuck due to substances inside the vacuum pump 1,
Although it is not possible to overcome the sticking force and start up, the present invention has made it possible, as shown in Fig. 2.

That is, as shown in FIG. 1, if a voltage of 200 V is applied directly to the drive unit 3 from the AC power source 8, the current will be excessive, so the capacity of the drive unit 3 must be increased. Therefore, in FIG. 2, a transformer 19 is installed between the drive section 3 and the first switch 13 to lower the voltage to the drive section 3 to about 50V and supply it.

Next, the first switch 13 is first turned on in response to a start command signal from another device, and the first switch 13 is turned on within a short time.
2 is turned off, and then the second switch 16 and the third switch 17 are turned on in that order.
The vacuum pump 1 can be automatically accelerated to a steady rotation speed by the start command signal.

This is possible, for example, by configuring the activation device as shown in FIGS. 3 to 5.

That is, as shown in FIG. 3, the inverter 7, the AC motor IM and the electromagnetic switches 13, 16 .
17 and the coil 14 are connected.

In addition, as shown in Fig. 4, the electromagnetic switch 13.16°1
In order to turn ON and OFF 7 sequentially, use L/-X, timer relay T of the oscillator relay B contact (break contact), timer relay T of the oscillator relay A contact (make contact),
,T, and the setting time of the timer relay T1°T, ,T, 11.1. ．． 13, each set time ti, t! t
If t:l is set to the relationship t<tt<ti, startup → first
Magnetic contactor 13 ON → 1st magnetic contactor 13 OFF → 2nd
The electromagnetic contactor 16 ON → the third electromagnetic contactor 17 ON operates in this order, which causes a coil to be generated from the AC power supply, starts the AC motor IM via the AC power supply, then temporarily stops the AC motor IM, and switches to the inverter to start AC power again. Motor IM can be driven.

Note that FIG. 5 shows the timer shown in FIGS. 3 and 4 above,
This is a time chart of the times T□, T, and T3, and shows the operating order of the three electromagnetic contactors 13, 16, and 17.

The operating state of the AC motor IM is shown.

[Effects of the Invention] Since the present invention is constructed as described above, it is possible to supply current with a large starting torque from the startup standby AC power source to the drive unit of the vacuum pump, and when the vacuum pump starts rotating, the inverter Supplies high frequency power from to the drive unit,
Vacuum pumps can be driven at high speed.

Therefore, the vacuum pump can be downsized and can be driven reliably.

[Brief explanation of drawings]

Fig. 1 is a circuit diagram showing a vacuum pump driving device which is an embodiment of the present invention, Fig. 2 is a circuit diagram showing a vacuum pump driving device which is another embodiment of the invention, and Fig. 3 is a circuit diagram showing a vacuum pump driving device which is an embodiment of the present invention. A circuit diagram showing a vacuum pump driving device according to yet another embodiment of the present invention, FIG. 4 is a circuit diagram for sequentially opening and closing the electromagnetic contactor shown in FIG. 3, and FIG. Fig. 4 is a time chart of the electromagnetic contactor, Fig. 6 is a circuit diagram of a conventional vacuum pump drive device, and Fig. 7 is a case in which a substance adheres between the rotor and stator of a conventional vacuum pump. FIG. DESCRIPTION OF SYMBOLS 1... Vacuum pump, 2... Hump part, 3... Drive part, 7... Inverter, 8... AC power supply, 13.1
6.17...Switch, 14...Coil. Agent Patent Attorney Tadashi Akimoto Business Diagram

Claims (1)

[Claims] 1. A stator fixed within a casing having an intake port and an exhaust port, and a drive shaft rotatably supported within the casing and supporting a rotor, the drive shaft being driven by an AC motor. A dry vacuum pump that, when driven, discharges gas sucked in from the intake port to the atmosphere from the exhaust port without containing liquid, comprising an AC power source and a high-frequency inverter as a driving power source for the AC motor, and the AC power source A dry vacuum pump drive device configured to switch between the high-frequency inverter and the high-frequency inverter using a switching means. 2. A drive device for a dry vacuum pump, wherein the switching means according to claim 1 is constituted by a plurality of electromagnetic switches. 3. A drive device for a dry vacuum pump, wherein each of the plurality of electromagnetic switches according to claim 2 is configured to be driven by a timer.