JPH0730792B2 - Magnetic bearing device - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a magnetic bearing device, and in particular, a passive magnetic bearing such as a permanent magnet is used in the radial direction.
The present invention relates to a magnetic bearing device that performs only uniaxial control using a controlled active magnetic bearing in the thrust direction.

[Prior Art] Recently, in order to reduce the manufacturing cost, three-axis control and one-axis control having a smaller number of control axes than five-axis control are about to be used for magnetic bearing devices for applications with less disturbance. In the case of uniaxial control, passive bearings are used in the radial direction, and only the axial direction is controlled. Such a uniaxial control type magnetic bearing device has the simplest control circuit and various contrivances have been made for practical use. However, since the uniaxial control type magnetic bearing device can hardly expect damping around the remaining uncontrolled four axes, unless some damping is applied, large vibration is generated when the natural vibration passes during rising or falling of rotation.

As such measures, Japanese Patent Publication No. 59-731 and Japanese Patent Publication No. 6
Japanese Patent Laid-Open No. 2-37246 discloses a technique of providing damping using an electric damping method, and there is also a method using a mechanical damper.

However, the above-mentioned electrical damping method shows effective damping only when the natural frequency and the rotation speed do not match, but when they match, that is, when the passing speed does not occur, a damping force is not generated, so it is practical. Not relevant. Further, in the case of the method using a mechanical damper, two independent repulsive radial magnetic bearings are used to control only the axial direction, but one repulsive radial magnetic bearing is elastically supported to form an attenuator. Has to be added, resulting in a very complicated structure.

Then, the inventors of the present application propose a magnetic bearing device in Japanese Patent Application No. 1-446324, which has a relatively simple structure and is capable of favorably attenuating vibration when passing through natural vibration during rising or falling of rotation. did.

FIG. 2A is a vertical cross-sectional view of the above proposed magnetic bearing device, and FIG. 2B is a horizontal cross-sectional view taken along the line IB-IB shown in FIG. 2A. Referring to FIGS. 2A and 2B, rotating shaft 1 rotates in case 2, and rotor 3 is attached to one end of rotating shaft 1. 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. A repulsive magnetic bearing 6 in the radial direction is formed by these permanent magnets 4 and 5.
Is configured. An upper emergency bearing 7 is attached to the inner surface of the case 2 facing one end of the rotary shaft 1. A motor stator 8 for rotating the rotating shaft 1 is provided at a substantially central portion of the case 2.

A permanent magnet holder 110 to which a thrust direction permanent magnet 109 is attached is provided below the motor stator 8. Thrust plate 1 facing the permanent magnet holder 110
1 is provided on the rotary shaft 1, and a permanent magnet 112 is provided above the thrust plate 11 so as to face the thrust direction permanent magnet 109 for attraction. An electromagnet 13 is provided below the thrust plate 11, and the electromagnet 13 is attached to the above-mentioned permanent magnet holder 110 by a spacer 14. The permanent magnet 13 is controlled by a control circuit (not shown) so as to balance with the axial attractive force generated between the permanent magnets 109 and 112.

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 on the other end of the rotating shaft 1. An axial position sensor 17 for detecting the 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. Then, the stator unit including the permanent magnet holder 110, the electromagnet 13, the spacer 14, and the axial direction 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 wire 19 so as to be strong in the axial direction and soft in the radial direction.

A plurality of damping members 20 are provided between the stator unit and the case 2.
Is inserted, and damping is applied to the vibration in the radial direction. Since the damping member 20 is exposed to vacuum for a long time, it is desirable to use silicone rubber.

In the magnetic bearing device configured as described above, the rotary shaft 1 has a radial magnetic repulsive force generated by the radial repulsive magnetic bearing 6 and a thrust plate formed by the electromagnet 13.
It is axially supported by the suction force with respect to 11, and is rotated by the rotational force of the motor stator 8. The stator unit is strongly supported in the axial direction by the steel wire 19, and the elastic member
Since it is supported softly in the radial direction by 20, the vibration can be satisfactorily damped when passing through the natural vibration when the rotating shaft 1 rotates up or down. The damping member 20 also serves as a rotation stop for the stator unit.

[Problems to be Solved by the Invention] According to the proposed magnetic bearing device described above, the fixed portion of the control magnetic bearing is rigidly supported in the axial direction by the support member, and is supported in the radial direction by the damping member. So
With a relatively simple structure, it is possible to satisfactorily damp vibrations when passing through natural vibrations when rotating or rising.

On the other hand, the uniaxial control type magnetic bearing device has a defect that the rigidity is small in addition to the above-mentioned defect that the damping force is small. This is because the remaining uncontrolled four axes utilize the repulsive force of the permanent magnets 4 and 5 or the tangential centripetal force of the axial attraction between the permanent magnets 109, 112 and the electromagnet 13. As described above, the uniaxial control type magnetic bearing device has a drawback that the damping force is small and a stiffness is small. Among them, the damping force can be solved by the method proposed by the present inventors. However, with respect to rigidity, there has been no means for effectively solving the problem. Further, when the radial rigidity is low, it is difficult to mount the spindle horizontally and use it.

The present invention has been made to solve the above problems, and an object of the present invention is to provide a magnetic bearing device having a large radial rigidity as compared with a conventional one and having a freely attachable position.

[Means for Solving the Problems] The magnetic bearing device according to claims 1 and 2 is a radial device that is provided at an upper portion and uses the repulsive force of a pair of permanent magnets that are arranged to face each other at substantially the same axial position. A single-axis control type magnetic bearing device in which a rotating shaft is axially supported by a magnetic bearing and a control type magnetic bearing provided in a lower portion, and a magnetic attraction force in an axial direction is controlled. And the second
And a cylindrical permanent magnet. The first cylindrical permanent magnet is mounted on the fixed portion of the controllable magnetic bearing substantially concentrically with the shaft. The second cylindrical permanent magnet faces the first cylindrical permanent magnet, and is mounted concentrically with the shaft by shifting the axial direction substantially concentrically. It is configured to have the same polarity as that of the first cylindrical permanent magnet and generate a repulsive force between the first cylindrical permanent magnet and the first cylindrical permanent magnet.

[Operation] In the magnetic bearing device according to the first and second aspects, the set of permanent magnets constituting the radial magnetic bearing provided in the upper part is arranged so as to face each other at substantially the same axial position without shifting the position in the bearing direction. Since the first cylindrical permanent magnets and the second cylindrical permanent magnets provided in the lower portion are configured to be displaced only in the axial position, a pair of permanent magnets facing each other at the same axial position are provided in the upper portion. Strong radial rigidity is obtained due to the strong radial repulsive force of the magnet. At the lower part, the radial centripetal force of the axial attractive force of the electromagnet and the radial component force of the repulsive force of the first and second cylindrical permanent magnets are A strong radial rigidity is obtained by the sum of. As a result, a strong radial rigidity can be obtained for the magnetic bearing device as a whole. Further, the axial component force of the repulsive force of the first and second cylindrical permanent magnets is balanced with the attractive force of the electromagnet, so that the electromagnet can control the axial direction. That is, since the first and second cylindrical permanent magnets have two roles, that is, the role of increasing the radial rigidity and the role of enabling the axial direction control by the electromagnet, the present invention enables the axial direction control with a simple structure. However, strong radial rigidity can be obtained for the magnetic bearing device as a whole.

Embodiment of the Invention FIG. 1 is a vertical sectional view of a magnetic bearing device showing an embodiment of the present invention. Referring to FIG. 1, the rotating shaft 1 is a case 2
The rotor 3 rotates inside, and a rotor 3 is attached to one end of the rotating shaft 1. 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 form a radial repulsive magnetic bearing 6. An upper emergency bearing 7 is attached to the inner surface of the case 2 facing one end of the rotary shaft 1. A motor stator 8 for rotating the rotating shaft 1 is provided at a substantially central portion of the case 2.

Below the motor stator 8, a permanent magnet holder 10 having a repulsive permanent magnet 9 mounted substantially concentrically with the rotary shaft 1 is provided. A thrust plate 11 is provided on the rotary shaft 1 so as to face the permanent magnet holder 10, and an upper portion of the thrust plate 11 faces the repulsive permanent magnet 9 and is displaced in the axial direction to repel the permanent magnet 12. Is provided. Thrust plate 11
An electromagnet 13 is provided in the lower part of the, and the electromagnet 13 is attached to the above-mentioned permanent magnet holder 10 by a spacer 14. The electromagnet 13 is controlled by a control circuit (not shown) so as to balance with the attractive force in the axial direction generated between the repulsive permanent magnets 9 and 12. The repulsive permanent magnets 9 and 12 generate a radial repulsive force in addition to the axial attractive force. This radial repulsive force acts as a radial uncontrolled bearing. As a result, the repulsive force radial generated by the repulsive permanent magnets 9 and 12 is larger than that of the conventional uncontrolled radial magnetic bearing that utilizes the radial centripetal force of the axial attractive force of the permanent magnet and the electromagnet. The radial stiffness can be increased only by the directional component.

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 on the other end of the rotating shaft 1. An axial position sensor 17 for detecting the 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. Then, the stator unit including the permanent magnet holder 10, the electromagnet 13, the spacer 14, and the axial direction 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 wire 19 so as to be strong in the axial direction and soft in the radial direction.

A plurality of damping members 20 are inserted between the stator unit and the case 2 to give damping to vibration in the radial direction.

As described above, in the present embodiment, the repulsive permanent magnets 9 and 12 are opposed to each other and are axially offset from each other so that the repulsive permanent magnets 9 and 12 are axially attracted to each other to balance the electromagnet. In addition, since a radial force is generated due to the repulsive force, it is possible to construct a bearing having a sufficiently large radial rigidity as compared with the radial bearing action by the conventional electromagnet.

[Advantages of the Invention] As described above, according to the first and second aspects of the present invention, the axial position of one set of permanent magnets constituting the upper radial bearing is not displaced and the lower first cylindrical type is used. By configuring the permanent magnet and the second cylindrical permanent magnet to be displaced in the axial position only, to obtain a strong radial rigidity by the strong radial repulsive force of a pair of permanent magnets facing each other at the same axial position in the upper part. At the bottom, strong radial rigidity can be obtained by the sum of the radial centripetal force of the axial attractive force of the electromagnet and the radial component force of the repulsive force of the first and second cylindrical permanent magnets. . Thereby, strong radial rigidity can be obtained in the magnetic bearing device as a whole. As a result, the mounting position is also free, and it can be sufficiently used even when placed horizontally. Also, the first
Also, the axial component force of the repulsive force of the second cylindrical permanent magnet is configured to be balanced with the attractive force of the electromagnet, so that the electromagnet can control the axial direction. As described above, the first and second cylindrical permanent magnets serve to enhance the radial rigidity and to enable axial control by the electromagnet, so that the present invention has a simple structure and enables axial control. It is possible to obtain strong radial rigidity as the entire magnetic bearing device.

[Brief description of drawings]

FIG. 1 is a vertical sectional view of a magnetic bearing device showing an embodiment of the present invention, FIG. 2A is a vertical sectional view of a magnetic bearing device proposed by the inventors of the present application, and FIG. 2B is shown in FIG. 2A. It is a cross-sectional view taken along line IB-IB. In the figure, 1 is a rotating shaft, 2 is a case, 3 is a rotor, and 4
Is a permanent magnet, 5 is a permanent magnet, 6 is a repulsive magnetic bearing in the radial direction, 7 is an upper emergency bearing, 8 is a motor stator, 9 is a repulsive permanent magnet, 10 is a permanent magnet holder, 11 is a thrust plate, 12 Is a repulsive permanent magnet, 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, and 20 is a damping member. is there. In the drawings, the same reference numerals indicate the same or corresponding parts.

Claims (2)

[Claims] 1. A radial magnetic bearing utilizing the repulsive force of a pair of permanent magnets provided at the upper part and arranged to face each other at substantially the same axial position, and an attractive magnetic force in the axial direction provided at the lower part. Is a single-axis control type magnetic bearing device in which a rotary shaft is axially supported by a control type magnetic bearing that is controlled by a first cylindrical type. The permanent magnet and the first cylindrical permanent magnet are opposed to the first cylindrical permanent magnet, and are mounted concentrically with each other by shifting the axial position integrally with the shaft, and the polarities of the surfaces facing the first cylindrical permanent magnet are set. A magnetic bearing device comprising: a second cylindrical permanent magnet that has the same polarity as that of the first cylindrical permanent magnet and generates a repulsive force between the first cylindrical permanent magnet and the first cylindrical permanent magnet. 2. The magnetic bearing device further comprises a support member for rigidly supporting at least the fixed portion of the control type magnetic bearing in the axial direction, and a damping member for supporting at least the radial direction of the control type magnetic bearing. The magnetic bearing device according to claim 1, further comprising: