JPH03255219A - Magnetic bearing device - Google Patents

Abstract

PURPOSE:To increase damping effect to the radial directional vibration by supporting the fixing part of a control-type magnetic bearing rigidly in the axial direction by means of a supporting member, and also supporting it softly in the radial direction by means of a viscoelastic damping member, and further by inserting a friction damper between the fixing part and the case. CONSTITUTION:In the lower part of a motor-stator 8, a permanent-magnet holder 10 to which a thrust-directionally attractive permanent magnet 9 is fitted is provided. An electromagnet 13 is fitted to the permanent-magnet holder 10 via a spacer 14. A stator unit consisting of the permanent-magnet holder 10, the electromagnet 13, the spacer 14, and an axial directional position sensor 17 is fitted to a case 2 by means of several steel wires 19. Between the stator unit and the case 2, a viscoelastic damping member 20 such as rubber is inserted. In this manner, since the fixing part consisting of the stator unit is rigidly supported in the axial direction, and is softly supported in the radial direction, and further, a friction damper consisting of a viscoelastic member is inserted between the fixing part and the case, damping effect to the vibration in the radial direction can be increased.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a magnetic bearing device, and in particular, in the radial direction, a passive magnetic bearing such as a permanent magnet is used,
The present invention relates to a magnetic bearing device that performs only one-axis control using a controlled active magnetic bearing in the thrust direction.

[Prior Art] Recently, in order to reduce manufacturing costs, three-axis control and one-axis control, which have fewer control axes than five-axis control, are being used in magnetic bearing devices for applications with less disturbance. . 1
In the case of axial control, passive bearings are used in the radial direction and only the axial direction is controlled. Such a single-axis control type magnetic bearing device has the simplest control circuit, and various improvements have been made to put it into practical use. However, in a single-axis controlled magnetic bearing device, almost no damping can be expected around the remaining four uncontrolled axes, so unless some kind of damping is provided, large vibrations will occur when the bearing passes through the natural vibration when the rotation is rising or falling. .

As a countermeasure to this problem, Japanese Patent Publication No. 59-7731 and Japanese Patent Publication No. 62-37246 disclose a technique for applying damping using an electrical damping method. There is also a method.

[Problems to be Solved by the Invention] However, the above-mentioned electrical damping method exhibits effective damping only when the natural frequency and rotation speed do not match, but when they match, that is, the natural vibration It is not practical because it does not produce any damping force when passing. In addition, in the case of a method using a mechanical damper, it is necessary to use two independent repulsion type radial magnetic bearings to elastically support one of the repulsion type radial magnetic bearings, and add a damper. The disadvantage is that it becomes complicated.

Therefore, the main object of the present invention is to provide a magnetic bearing device that is newly provided with a damper to enhance the damping effect against vibrations in the radial direction.

[Means for Solving the Problem] The invention according to the first claim supports a rotating shaft by a radial magnetic bearing that utilizes the repulsive force of a permanent magnet and a control type magnetic bearing that controls an axial magnetic force, This is a single-axis controlled magnetic bearing device that utilizes radial rigidity generated by axial attraction force, and includes a support member for rigidly supporting the fixed part of the controlled magnetic bearing in the axial direction, and a supporting member for rigidly supporting the fixed part of the controlled magnetic bearing. It is configured to include a viscoelastic damping member for soft support in the radial direction, and a friction damper made of an elastic body inserted between the fixed member and the case.

[Operation] The magnetic bearing device according to the present invention rigidly supports the fixed part of the control type magnetic bearing in the axial direction by the support member, supports it softly in the radial direction by the viscoelastic damping member, and further supports the fixed part of the control type magnetic bearing in the radial direction. By inserting a friction damper between them, it is possible to enhance the damping effect against vibrations in the radial direction.

[Embodiment of the invention] FIG. 1 is a longitudinal cross-sectional view of one embodiment of the invention, FIG. 2 is a cross-sectional view taken along the line ■-■ shown in FIG. 1, and FIG. FIG. 2 is a cross-sectional view taken along the line ■-■ shown in the figure.

Referring to FIGS. 1 to 3, a rotating shaft 1 rotates within a case 2, and a rotor 3 is attached to one end of the rotating shaft 1. As shown in FIGS. A permanent magnet 4 is provided on the inner surface of the rotor 3, and a permanent magnet 5 is provided on the outer surface of the case 2 facing the permanent magnet 4. These permanent magnets 4
and 5 constitute a repulsion type magnetic bearing 6. In addition,
An upper emergency bearing 7 is attached to the inner surface of the case 2 facing one end of the rotating shaft 1. A motor stator 8 for rotating the rotating shaft 1 is provided approximately in the center of the case 2 .

A permanent magnet holder 10 to which a permanent magnet 9 for thrust direction attraction is attached is provided at the lower part of the motor stator 8 . A thrust plate 11 is provided on the rotating shaft 1 so as to face the permanent magnet holder 10, and a permanent magnet 12 is provided on the upper part of the thrust plate 11 so as to face the permanent magnet 9 for attraction in the thrust direction. An electromagnet 13 is provided at the bottom of the thrust plate 11, and this electromagnet 13 is attached to the above-mentioned permanent magnet holder IO via a spacer 14. The electromagnet 13 is controlled by a control circuit (not shown) so as to balance the axial attraction force generated between the permanent magnets 9 and 12.

A lower emergency bearing 15 is provided on the inner surface of the electromagnet 13 facing the rotating shaft 1, and an axial sensor target 16 is provided at the other end of the rotating shaft 1.

An axial position sensor 17 for detecting an axial position is fixed to the lower surface of the electromagnet 13 by a sensor mounting member 18 so as to face the axial sensor target 16 . A stator unit consisting of a permanent magnet holder 10, an electromagnet 13, a spacer 14, and an axial position sensor 17 is attached to the case 2 by several steel wires 19.

As a result, the stator unit is supported by the steel wires 19 to be rigid in the axial direction and soft in the radial direction.

As shown in FIG. 3, grooves are formed along the axial direction at several locations between the stator unit and the case 2, into which viscoelastic damping members 20 such as rubber are inserted. Damping is provided to the vibration of
It plays the role of preventing the stator unit from rotating.

By the way, when the rotor 3 having a large moment of inertia, such as a turbo molecular pump, is rotated at high speed, the natural frequency changes with the rotational speed due to the gyroscopic moment, and forward and rearward natural frequencies are generated. The rear natural frequency can be damped by the damping member 20 made of a viscoelastic material such as the rubber. However, this damping member 20 has low damping performance for high frequencies such as the front rotation natural frequency.

Therefore, in one embodiment of the present invention, a friction damper 21 as shown in FIG. 2 is inserted between the stator unit 8 and the case 2. The friction damper 21 shown in FIG. 2 is inserted between the stator unit and the case 2 by stacking several thin spring plates.

Thereby, the stator unit is pressed in the radial direction. By providing the friction damper 21 in this way, frictional force is generated between the stator unit and the leaf spring or between the leaf springs due to the vibration of the stator unit.
Vibration energy is absorbed by this frictional force, and vibration of the stator unit can be suppressed.

FIG. 4 is a sectional view of a main part showing another embodiment of the present invention. In the example shown in FIG. 4, a leaf spring 2 is attached to the bottom of the case 2.
2 is arranged, and a friction material 23 is inserted between the leaf spring 22 and the stator unit, and the friction material 23 and the leaf spring 22 are pressed in the axial direction. The vibration in the radial direction of the stator unit is caused by the vibration between the stator unit and the friction material 23.
damped by the frictional force of

[Effects of the Invention] As described above, according to the present invention, the fixed part consisting of the stator unit is supported rigidly in the axial direction and supported softly in the radial direction, and there is a viscoelastic bond between the fixed part and the case. Since a friction damper made of a body is inserted, it is possible to enhance the damping effect against vibrations in the radial direction.

[Brief explanation of drawings]

FIG. 1 is a longitudinal sectional view of an embodiment of the present invention. FIG. 2 is a cross-sectional view taken along line -H shown in FIG. FIG. 3 is a cross-sectional view taken along the line ■--■ shown in FIG. FIG. 4 is a longitudinal sectional view showing the main parts of another embodiment of the invention. In the figure, 1 is the rotating shaft, 2 is the case, 3 is the rotor, and 4
．． 5. 9. 12 is a permanent magnet, 6 is a repulsive magnetic bearing, 7 is an upper emergency bearing, 8 is a motor stator, 1
0 is a permanent magnet holder, 11 is a thrust plate, 13 is an electromagnet, 14 is a spacer, 15 is a lower emergency bearing, 16
is an axial sensor target, 17 is an axial position sensor, 18 is a sensor mounting member, 19 is a steel wire, 20
is a viscoelastic damping member, 21 and 23 are friction dampers, and 22 is a leaf spring.

Claims (3)

[Claims] (1) A single-axis control type that uses the radial rigidity generated by the axial attractive force to support the rotating shaft with a radial magnetic bearing that uses the repulsive force of a permanent magnet and a control type magnetic bearing that controls the axial magnetic force. In the magnetic bearing device, a support member for rigidly supporting the fixed portion of the control type magnetic bearing in the axial direction; and a viscoelastic damping member for supporting the fixed portion of the control type magnetic bearing soft in the radial direction. A magnetic bearing device comprising: a friction damper made of an elastic body inserted between the fixing portion and the case, the magnetic bearing device having an enhanced damping effect against vibrations in the radial direction. (2) The magnetic bearing device according to claim 1, wherein the friction damper is inserted in the axial direction at a plurality of locations between the fixed portion and the case. (3) The magnetic bearing device according to claim 1, wherein the friction damper is inserted between an end surface of the fixed portion and a bottom surface of the case.