JPH11230167A - Magnetic bearing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enlarge adhering width of a magnetic body dust with keeping five axis control without specifically enlarging a magnetic bearing. SOLUTION: This bearing device is so constituted that a circulating fan 2 is installed in an airtight container l into which process gas 3 mixed with magnetic dust is filled and a rotor of the circulating fan 2 is supported by a five axis control magnetic bearing. In this case, radial magnetic bearings 4, 5 of the five axis control magnetic bearing is constituted with a passive type magnetic bearing having a stator side permanent magnet and a rotor side permanent magnet and an active type magnetic bearing having a stator side electromagnet and a rotor side magnetic pole, the active type magnetic bearing is installed on the airtight container 1 side, and clearance between a stator side electromagnet and the rotor side magnetic pole of the active type magnetic bearing is larger than clearance between the stator side permanent magnet and the rotor side permanent magnet of the passive type magnetic bearing.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a circulating fan for circulating a gas in a hermetically sealed container filled with a process gas having magnetic dust, and a rotor of the circulating fan is supported by a magnetic bearing. The present invention relates to a magnetic bearing device having a configuration.

[0002]

2. Description of the Related Art FIG. 3 is a diagram showing a configuration example of a conventional apparatus in which a circulation fan is installed in an airtight container. As shown in the drawing, the present apparatus has a circulation fan 2 installed in an airtight container 1 and a drive side rotor 2-1 and a non-drive side rotor 2-2 of the circulation fan 2 are connected to radial magnetic bearings 4, 5 and an axial magnetic field. The bearings 6 and 7 are rotatably supported by five-axis control type magnetic bearings.

[0003] A process gas 3 having a corrosive property required for various chemical processes and physical processes is sealed in a hermetic container 1 at a predetermined pressure, and the circulating fan 2 circulates the process gas 3 in the hermetic container 1. Thereby, a predetermined process is performed. Reference numeral 8 denotes a motor for driving the circulation fan 2.

[0004] An excimer laser device, for example, which utilizes the above-described device, uses a highly reactive halogen gas as the process gas 3. Therefore, the inside of the hermetic container 1 is resistant to the halogen gas. A highly corrosive Ni or a Ni-plated metal material is often used.

However, at the time of laser oscillation, the laser gas is excited by the discharge between the discharge electrodes, so that Ni or Ni-plated metal material in the laser tube is sputtered, and N gas chemically reacted with Ni powder or halogen gas in the laser gas.
i powder is generated. Since this Ni powder is a ferromagnetic material, it adheres to the magnets constituting the magnetic bearing, accumulates in the clearance between the rotor side and the stator side, and forms the drive side rotor 2-1 and the non-drive side rotor 2-2 of the circulation fan 2. There is a problem that hinders rotation. As a countermeasure against this, conventionally, the clearance between the rotor side and the stator side is made as large as possible so that rotation is not hindered even if magnetic dust adheres to the magnet constituting the magnetic bearing.

[0006]

However, in the above-mentioned conventional method, the clearance between the rotor and the stator of the magnetic bearing is increased as the dust allowance on the magnet constituting the magnetic bearing is increased. There is a disadvantage that the magnetic force of the magnet constituting the magnetic bearing must be increased.

In general, the magnetic force between the magnets decreases in proportion to the square of the clearance. Therefore, doubling the clearance requires a magnetic bearing having a magnetic force four times as large. One way to increase the magnetic force without changing the size of the magnetic bearing is to use permanent magnets, but this is a passive magnetic bearing that loses the control shaft and makes it difficult to control rotation and support. was there. Further, in the passive type magnetic bearing, since the magnetic force cannot be controlled, it is difficult to clean dust adhering to the magnetic bearing.

SUMMARY OF THE INVENTION The present invention has been made in view of the above points, and has as its object to provide a magnetic bearing device capable of increasing a dust allowance without increasing the size of a magnetic bearing and maintaining five-axis control. And

[0009]

According to a first aspect of the present invention, a circulating fan is installed in an airtight container filled with a process gas mixed with magnetic dust. A magnetic bearing device having a configuration in which a rotor is supported by magnetic bearings, wherein a radial bearing of the magnetic bearing includes a passive magnetic bearing including a stator-side permanent magnet and a rotor-side permanent magnet, a stator-side electromagnet, and a rotor-side magnetic pole. The active magnetic bearing is installed on the airtight container side, and the clearance between the stator-side electromagnet and the rotor-side magnetic pole of the active magnetic bearing is changed to the stator-side permanent magnet and the rotor of the passive magnetic bearing. The clearance is made larger than the clearance of the side permanent magnet.

[0010] The invention described in claim 2 is the same as the claim 1.
Wherein the current to the stator-side electromagnet of the active magnetic bearing is interrupted during cleaning.

[0011]

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 device having a circulation fan using the magnetic bearing device of the present invention. Note that, in FIG. 1, portions denoted by the same reference numerals as those in FIG. 3 indicate the same or corresponding portions.

In the present apparatus, a process gas 3 having a corrosive property required for various chemical processes and physical processes is sealed in a hermetic container 1 at a predetermined pressure, and the process gas 3 is filled in the hermetic container 1 by a circulation fan 2. The point that a predetermined process is performed by circulation is the same as that of the apparatus shown in FIG.

On both sides of the circulation fan 2, a driving rotor 2
-1 and the anti-drive side rotor 2-2 are attached. The driving-side rotor 2-1 is rotatably supported by a radial magnetic bearing 4 and an axial magnetic bearing 6, and the anti-driving-side rotor 2-2.
Are rotatably supported by a radial magnetic bearing 5 and an axial magnetic bearing 7. The drive-side rotor 2-1 is driven to rotate by a motor 8.

The drive side rotor 2-1 has a rotor side magnetic pole 4-1 of the radial magnetic bearing 4 and a displacement sensor target 4-2.
And the rotor-side permanent magnetic pole 4-3, the rotor 8-1 of the motor 8,
The displacement sensor target 6-1 of the axial magnetic bearing 6 and the rotor-side magnetic pole 6-2 are mounted. Similarly, the rotor 2-2 of the radial magnetic bearing 5, the displacement sensor target 5-2, the permanent magnet pole 5-3 of the rotor, and the displacement sensor target 7 of the axial magnetic bearing 7 are also provided on the non-drive side rotor 2-2. -1 and the rotor-side magnetic pole 7-2 are attached.

A drive casing 9 is provided on both sides of the airtight container 1.
And an anti-drive side casing 10. The drive-side casing 9 includes a casing body 9-1, a protective bearing housing 9-2, and a bearing cover 9-3. The casing body 9-1 includes a stator-side electromagnet 4-4 of the radial magnetic bearing 4, a displacement sensor 4-5, and a stator-side permanent magnet 4-
6 and a stator 8-2 of the motor 8 are accommodated. The protective bearing housing 9-2 houses the protective bearing 11. Further, the airtight container 1 of the casing body 9-1.
A can 14 is fixed to the inner peripheral end of the side and the inner peripheral end of the side plate 13 by welding or the like.

The non-drive side casing 10 comprises a casing body 10-1, a protective bearing housing 10-2, and a bearing cover 10-3. The casing body 10-1 houses the stator-side electromagnet 5-4 of the radial magnetic bearing 5, the displacement sensor 5-5, and the stator-side permanent magnetic pole 5-6.
The protective bearing housing 10-2 houses the protective bearing 12. A can 17 is fixed to the inner peripheral end of the casing body 10-1 on the airtight container 1 side and the inner peripheral end of the side plate 16 by welding or the like.

The stator magnetic pole 6-3 of the axial magnetic bearing 6 is mounted on the airtight container 1 side of the bearing cover 9-3, and a can 15 is welded to the outer surface of the stator magnetic pole 6-3. Is fixed. The displacement sensor 6-4 of the axial magnetic bearing 6 is provided on a thin partition wall of the bearing cover 9-3.

On the side of the airtight container 1 of the bearing cover 10-3,
A stator-side magnetic pole 7-3 of the axial magnetic bearing 7 is attached, and a can 18 is fixed to an outer surface of the stator-side magnetic pole 7-3 by welding or the like. The displacement sensor 7-4 of the axial magnetic bearing 7 is provided with a bearing cover 10-.
3 is installed in the thin partition.

FIG. 2 is a view showing a detailed structure of the radial magnetic bearing 4 and the motor 8 of the drive side casing 9. Stator-side electromagnet 4-4 of radial magnetic bearing 4 and displacement sensor 4
-5, the stator-side permanent magnetic poles 4-6, and the stator 8-2 of the motor 8 are fixed to the casing body 9-1 in a state where their relative positions are determined by the spacers 19-1, 19-2, 19-3, and the side plate 13. Is housed.

On the other hand, the drive-side rotor 2-1 is provided with a rotor-side magnetic pole 4-1, a displacement sensor target 4-2, a rotor-side permanent magnetic pole 4-3, a rotor 8-1 of the motor 8, and the like. Then, the stator-side electromagnet 4-4, the displacement sensor 4-
5. The thin cylindrical can 14 is inserted into the inner peripheral surface of the stator-side permanent magnet 4-6 and the stator 8-2 of the motor 8, and both ends are fixed by welding or the like.

Here, the clearance d2 between the rotor-side magnetic pole 4-1 and the stator-side electromagnet 4-4 located closest to the hermetic container 1 is changed by the rotor-side permanent magnet 4-3 and the stator-side permanent magnet 4-6. (D2> d1). The magnetic force is set to be stronger between the rotor side magnetic pole 4-1 and the stator side electromagnet 4-4 than between the rotor side permanent magnet 4-3 and the stator side permanent magnet 4-6.

Although not shown, the detailed configuration of the radial magnetic bearing 5 is the same as that of the radial magnetic bearing 4. The clearance between the rotor-side magnetic pole 5-1 and the stator-side electromagnet 5-4 at a position close to the hermetic container 1 of the radial magnetic bearing 5 is set between the rotor-side permanent magnet 5-3 and the stator-side permanent magnet 5-6. Is larger than the clearance. Also, the magnetic force between the rotor-side permanent magnet 5-1 and the stator-side electromagnet 5-4 is made stronger than that between the rotor-side permanent magnet 5-3 and the stator-side permanent magnet 5-6.

By adopting the above configuration for the radial magnetic bearings 4 and 5, the magnetic substance dust contained in the process gas 3 in the airtight container 1 is adsorbed by the stator-side electromagnets 4-4 and 5-4. It does not penetrate deeper. That is,
Rotor-side permanent magnets 4-3, 5 constituting passive magnetic bearing
-3, the stator-side permanent magnets 4-6 and 5-6, and the axial magnetic bearings 6 and 7 are free of magnetic dust.

As described above, the radial magnetic bearings 4 and 5
, That is, passive magnetic bearings composed of active magnets (rotor-side magnetic poles 4-1 and 5-1 and stator-side electromagnets 4-4 and 5-4) each composed of an electromagnet and permanent magnets Since the active magnetic bearings are arranged on the side of the hermetic container 1 as the (rotor-side permanent magnets 4-3, 5-3 and the stator-side permanent magnets 4-6, 5-6), the magnetic dust is reduced to the active magnetic bearing. It is adsorbed only by the passive magnetic bearing and the axial magnetic bearings 6 and 7.

Although the magnetic dust is attracted to the active magnetic bearing, the clearance between the rotor side and the stator side of the active magnetic bearing (rotor-side magnetic poles 4-1 and 5-1 and stator-side electromagnet 4). -4 and 5-4) between the rotor side and the stator side of the passive magnetic bearing (the rotor-side permanent magnets 4-3 and 5-3 and the stator-side permanent magnets 4-6 and 5-5). 6) and the allowance for the adhesion of the magnetic substance dust is increased, so that the rotation of the rotor is not hindered even if the magnetic substance dust adheres.

Since each of the radial magnetic bearings 4 and 5 is divided into an active magnetic bearing and a passive magnetic bearing, the clearance between the rotor side and the stator side of the active magnetic bearing alone is increased. Radial magnetic bearings 4 and 5
Is smaller than the clearance between the same rotor side and the same stator side with the active magnetic bearing alone. Further, since each of the radial magnetic bearings 4 and 5 has an active magnetic bearing, 5-axis control can be maintained, and stable control of the circulation fan 2 can be easily performed.

At the time of cleaning, the electromagnets (stator side electromagnets 4-4 and 5-
By interrupting the current to 4), the magnetic force of the active magnetic bearing disappears, so that cleaning of the magnetic dust becomes easy.

In the above-described embodiment, an excimer laser device has been described as an application example of the magnetic bearing device. However, the present invention is applied to a magnetic bearing device in which magnetic substance dust is present in the gas circulated by the circulation fan 2. Obviously it is good.

Further, in the above-described embodiment, a description has been given of a 5-axis control type magnetic bearing as an example, but the present invention is not limited to a 5-axis control type magnetic bearing.

[0030]

As described above, according to the first aspect of the present invention, the radial bearing is formed of a passive magnetic bearing having a permanent magnet on the stator side and a permanent magnet on the rotor side, an electromagnet on the stator side, and a magnetic pole on the rotor side. The active magnetic bearing is provided on the airtight container side, and the clearance between the stator-side electromagnet and the rotor-side magnetic pole of the active magnetic bearing is set on the stator-side permanent magnet and the rotor side of the passive magnetic bearing. Since the clearance is made larger than the clearance of the permanent magnet, the following excellent effects can be obtained.

Since the magnetic dust adheres only to the active magnetic bearing, the rotation of the circulating fan is hindered even if the magnetic dust adheres to the large magnetic dust even if the radial magnetic bearing is not enlarged. There is no. As a result, the maintenance interval becomes longer, and the device can be operated continuously for a long time.

Further, since the radial bearing is divided into an active magnetic bearing and a passive magnetic bearing, the number of control shafts can be maintained at 5, and a stable control system can be easily obtained.

According to the second aspect of the present invention, the magnetic force of the active magnetic bearing disappears by cutting off the current to the electromagnet constituting the active magnetic bearing at the time of cleaning. Cleaning becomes easier.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration example of a device having a circulation fan using a magnetic bearing device of the present invention.

FIG. 2 is a view showing a detailed structure of a radial magnetic bearing and a motor of a drive-side casing of FIG. 1;

FIG. 3 is a diagram illustrating a configuration example of a device including a circulation fan using a conventional magnetic bearing device.

[Explanation of symbols]

 Reference Signs List 1 airtight container 2 circulation fan 3 process gas 4 radial magnetic bearing 4-1 rotor-side magnetic pole 4-2 displacement sensor target 4-3 rotor-side permanent magnet 4-4 stator-side electromagnet 4-5 displacement sensor 4-6 stator-side permanent magnet Reference Signs List 5 Radial magnetic bearing 5-1 Rotor-side magnetic pole 5-2 Displacement sensor target 5-3 Rotor-side permanent magnet 5-4 Stator-side electromagnet 5-5 Displacement sensor 5-6 Stator-side permanent magnet 6 Axial magnetic bearing 7 Axial magnetic bearing 8 Motor 9 Drive side casing 10 Non-drive side casing 11 Protective bearing 12 Protective bearing 13 Side plate 14 Can 15 Can 16 Side plate 17 Can 18 Can

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Takeshi Kawamura 11-1 Haneda Asahimachi, Ota-ku, Tokyo Inside Ebara Corporation

Claims (2)

[Claims] 1. A magnetic bearing device having a configuration in which a circulation fan is installed in an airtight container filled with a process gas mixed with magnetic dust and a rotor of the circulation fan is supported by a magnetic bearing. The radial bearing of the magnetic bearing is composed of a passive magnetic bearing having a stator-side permanent magnet and a rotor-side permanent magnet, and an active magnetic bearing having a stator-side electromagnet and a rotor-side magnetic pole, and the active magnetic bearing is hermetically sealed. And a clearance between the stator-side electromagnet and the rotor-side magnetic pole of the active type magnetic bearing is made larger than a clearance between the stator-side permanent magnet and the rotor-side permanent magnet of the passive type magnetic bearing. 2. The magnetic bearing device according to claim 1, wherein a current to the stator-side electromagnet of the active magnetic bearing is interrupted during cleaning.