WO1997013985A1

WO1997013985A1 - Magnetic bearing device

Info

Publication number: WO1997013985A1
Application number: PCT/JP1996/002812
Authority: WO
Inventors: Yasushi Maejima
Original assignee: Seiko Seiki Kabushiki Kaisha
Priority date: 1995-10-11
Filing date: 1996-09-27
Publication date: 1997-04-17
Also published as: JPH09105412A

Abstract

A magnetic bearing device comprising a protective bearing that makes contact with a rotating shaft in the beginning to prevent vibrations so that the shaft speed may increase stably and reach a steady state. A frusto-conical portion (24) (tapered linearly or otherwise) is formed between a larger-diameter portion (21) and an intermediate-diameter portion (22) of the shaft (2). The surface of the frusto-conical portion (24) can freely make contact with an inner edge of the inner race (71) of the protective bearing (7). When the shaft (2) begins rotating, therefore, the surface of the frusto-conical portion (24) of the shaft (2) is brought into contact with the inner edge of the protective bearing (7). Accordingly, the shaft (2), the vibrations of the shaft (2) is absorbed by the protective bearing (7) via the surface of the frusto-conical portion (24), so that the vibrations of the rotary shaft (2) can be minimized.

Description

Magnetic bearing device Technical field

The present invention relates to a magnetic bearing device applied to a turbo molecular pump or a spindle of a machine tool. Background art

Conventionally, as a magnetic bearing device incorporated and used in a turbo molecular pump, for example, a three-axis control type as shown in FIG. 8 is known.

This magnetic bearing device has a cylindrical mounting frame 1 which is open at both ends, and a high frequency motor 3 for driving a rotating shaft 2 is disposed at the center of the mounting frame 1. The rotary shaft 2 is configured to magnetically support the radial direction by the radial bearing 4 and to axially support the axial direction by the thrust bearing 5. The radial bearing 4 is an inner periphery of the mounting frame 1. It is formed of a radial electromagnet 4 1 attached to the surface and a rotor core 4 2 attached to the rotary shaft 2 corresponding to the radial electromagnet 4 1. The thrust bearing 5 is attached to the inner peripheral surface of the mounting frame 1. The axial electromagnet 51, the armature disc 52 and the permanent magnet 53 integrally attached to the lower end of the rotary shaft 2, and the permanent magnet The permanent magnet 54 is formed to face the magnet 53. The upper inner circumferential surface of the mounting frame 1 and the inner circumferential surface of the axial electromagnet 51 are protected by a rolling bearing or the like to protect the radial bearing 4 or the thrust bearing 5 from abnormal rotation of the rotary shaft 2 or the like. Bearings 6, 7 are provided.

The rotating shaft 2 is composed of a large diameter portion 21, a medium diameter portion 22 inserted into the protective bearing 7, and a small diameter portion 23 for attaching a magnetic disc 52 and the like. These are a large diameter portion 21, The diameter is formed to be smaller in the order of the medium diameter portion 22 and the small diameter portion 23. Small diameter portion 2 3 of rotating shaft 2 The swinging of the rotating shaft is received by the rotating shaft runout suppressing bearing, and the swinging of the rotating shaft is suppressed. Brief description of the drawings

FIG. 1 is a cross-sectional view of a magnetic bearing device according to a first embodiment of the present invention.

FIG. 2 is a block diagram showing a configuration of a control system of the same magnetic bearing device.

FIG. 3 is a view for explaining the operation of the same magnetic bearing device.

FIG. 4 is a view showing another example of the frusto-conical portion of the same magnetic bearing device.

FIG. 5 is a cross-sectional view of a magnetic bearing device according to a second embodiment of the present invention.

FIG. 6 is a block diagram showing a configuration of a control system of the same magnetic bearing device.

FIG. 7 is a view for explaining the operation of the same magnetic bearing device.

FIG. 8 is a schematic cross-sectional view showing the configuration of a conventional magnetic bearing device, and hatching is omitted as appropriate in order to make the drawing easy to see. BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, embodiments of the present invention will be described in detail with reference to FIGS. 1 to 7. FIG. 1 shows the configuration of the thrust bearing 5 and the protective bearing 7 which are main parts in the magnetic bearing device of the first embodiment of the present invention. The magnetic bearing device of the first embodiment has substantially the same configuration as the magnetic bearing device described in FIG. 8 except for the thrust bearing 5 and the protective bearing 7 parts, so the same reference numerals are given to the same parts. The explanation is omitted appropriately.

In this magnetic bearing device, as shown in FIG. 1, a frusto-conical portion 2 4 having a tapered surface which linearly changes in the axial direction between the large diameter portion 2 1 and the medium diameter portion 2 2 of the rotating shaft 2. And the tapered surface of the second truncated conical portion 2 is formed so as to be in contact with the inner side edge of the inner ring 71 of the protective bearing 7. The contact surface (crop surface) of the frusto-conical portion 24 has a curvature, as shown in Fig. 4 (A), as in the frusto-conical portion 24 A or in Fig. 4 (B). It may be a contact surface that has a curved surface in the axial direction. Also, the contact between the frusto-conical portion 24 and the inner ring 7 1 of the protective bearing 7 may be in any configuration as long as it contacts at three or more points. The aim is to reach the numbers. Disclosure of the invention

In the present invention, the rotating shaft and the radial direction of the rotating shaft are magnetically supported.

A three-axis control type magnetic bearing device comprising: a radial bearing, a thrust bearing for magnetically supporting the axial direction of the rotating shaft, and a protective bearing for protecting the radial bearing and the thrust bearing; A control means is provided to form a contact between the rotary shaft and the protective bearing, and to control the rotary shaft to temporarily contact the protective bearing when the rotary shaft starts to rotate. Achieve the goal.

Further, in the magnetic bearing device according to the present invention, in the contact portion between the rotary shaft and the protective bearing, an inclined surface is formed on at least one of the rotary shaft and the protective bearing; The above object is achieved by bringing the shaft and the protective bearing into contact with each other.

Furthermore, in the present invention, a rotary shaft, a radial bearing that magnetically supports the radial direction of the rotary shaft, a thrust bearing that magnetically supports the axial direction of the rotary shaft, the radial bearing, and the thrust bearing. A three-axis control type magnetic bearing device provided with a protective bearing for protecting the bearing, and a rotational shaft runout suppressing bearing for suppressing the runout of the rotary shaft, and when the rotation of the rotary shaft rises, The object is achieved by providing a control means for controlling the rotational shaft runout suppressing bearing to temporarily support the rotational shaft.

By this, in the present invention, the control means controls the rotational shaft and the protective bearing to be in temporary contact with each other at the time of the rise of the rotation of the rotational shaft, so that the swing of the rotational shaft is received by the protective bearing. Rotation of the rotating shaft is suppressed. Further, in the present invention, when the rotation of the rotation shaft rises, the rotation shaft and the protective bearing are temporarily brought into contact with each other, and the rotation of the rotation shaft is received by the protection bearing, so that the rotation of the rotation shaft is suppressed.

Furthermore, in the present invention, the control means controls the rotational shaft runout suppressing bearing to temporarily support the rotational shaft at the time of start of rotation of the rotational shaft. The inner weight of the inner ring 71 does not cover the inner edge of the inner ring 71. Therefore, in the control circuit 12, the determined radial and axial positions of the rotary shaft 2 become the target positions, and the weight of the rotary shaft 2 is from the inner surface side edge of the inner ring 71. Control each exciting current of radial electromagnet 41 and axial electromagnet 51 so as not to be in the state.

Thus, when the high frequency motor 3 is energized, the rotary shaft 2 magnetically floated to the predetermined position is gradually accelerated from the stationary state and shifts to the rated rotation speed. However, when the rotation of rotation shaft 2 is started up, as described above, in the axial direction of rotation shaft 2, the tapered surface of its truncated conical portion 2 is in contact with the edge surface side edge of inner ring 7 1 of protective bearing 7. It is controlled to become. Therefore, even when the number of revolutions of the rotary shaft 2 reaches near the primary resonance point (the resonance point of the rigid mode) at the rise of the rotation of the rotary shaft 2, the swinging of the rotary shaft 2 is Since the tapered surface is received by the protective bearing 7, the rotary shaft 2 does not swing much.

After that, when the rotation speed of the rotation shaft 2 detected by the rotation speed sensor 16 passes the primary resonance point, the target position in the axial direction of the rotation shaft 2 is changed to the position of steady rotation. As shown in Fig. 3 (B), it rises from the state shown in Fig. 3 (A) and does not contact the protective bearing 7. When the rotary shaft 2 is elevated, the conical portion 24 has a tapered surface, so the elevation is performed quickly and smoothly. Thereafter, the rotational shaft 2 is controlled by the control circuit 12 so that the position in the axial direction becomes the position of steady rotation.

According to the first embodiment described above, the tapered surface of the frusto-conical portion 24 of the rotary shaft 2 is brought into contact with the inner end of the protective bearing 7 when the rotation of the rotary shaft 2 rises. Therefore, at the rise of the rotation of the rotary shaft 2, it is avoided that the protective bearing 7 and the rotary shaft 2 rotate together even after the resonance point, and the steady rotation speed can be reached.

In the first embodiment described above, the rotary shaft 2 is provided with a truncated cone portion 24 and the tapered surface of the truncated cone portion 24 is in contact with the end face of the inner ring 71 of the protective bearing 7 in a self-existent manner. I did. However, in the present invention, the rotary shaft 2 and the protective bearing 7 can be in contact with each other. FIG. 2 shows the configuration of the control system of the magnetic bearing device of FIG. The control system of this magnetic bearing device controls the magnetic levitation position of the rotary shaft 2 to the target position of the radial bearing 4 and thrust bearing 5 and suppresses the swinging of the rotary shaft 2 when the rotation of the rotary shaft 2 rises. In order to control the axial position of the rotary shaft 2, a control circuit 12 is provided.

That is, the radial direction sensor 10, the axial direction sensor 11 and the rotational speed sensor 16 for detecting the rotational speed of the rotary shaft 2 are connected to the input side of the control circuit 12, and the radius on the output side of the control circuit 12. Directional electromagnet 4 1 and axial electromagnet 5 1 are connected. Then, the control circuit 12 determines the position of the rotary shaft 2 based on the detection displacements of both the radial sensor 10 and the axial sensor 11 and compares the calculated position of the rotary shaft 2 with the target position. The excitation currents of the radial electromagnets 4 1 and the axial electromagnets 5 1 are controlled so that the rotation axis 2 is at the target position. Furthermore, in addition to the above control, control circuit 12 temporarily sets the tapered surface of frusto-conical portion 24 of rotation shaft 2 to the inner surface side edge of inner ring 71 of protection bearing 7 when rotation of rotation shaft 2 rises. Control to control the rotation of the rotary shaft 2 by making contact.

Next, the operation of the first embodiment configured as described above will be described.

Now, when the power is turned on, the rotating shaft 2 of the magnetic bearing device is magnetically levitated by the radial electromagnets 4 1 and the axial electromagnets 5 1. The control circuit 12 receives the radial displacement of the rotary shaft 2 detected by the radial sensor 10 and the axial displacement of the rotary shaft 2 detected by the axial sensor 11. The control circuit 12 determines the radial and axial positions of the rotary shaft 2 based on the detected displacement, compares the calculated position of the rotary shaft 2 with the target position, and achieves the target position in the radial direction. Control each exciting current of electromagnet 4 1 and axial electromagnet 5 1. By the way, when the rotation of the rotation shaft 2 rises (when it starts), the target position of the rotation shaft 2 in the radial direction is the center position of the radial bearing 4. The target position in the axial direction of the rotary shaft 2 is the position where the tapered surface of the truncated cone 24 comes into contact with the inner edge of the inner ring 7 1 of the protective bearing 7 as shown in FIG. 3 (A). And the axis of rotation 2 FIG. 6 shows the structure of the control system of the magnetic bearing device of FIG. In the control system of this magnetic bearing device, the magnetic levitation position of the rotary shaft 2 is controlled to the target position of the radial bearing 4 and thrust bearing 5, and the swing of the rotary shaft 2 is In order to suppress this, a control circuit 14 for controlling the axial position of the rotational shaft runout prevention bearing 13 is provided. That is, the radial direction sensor 10, the axial direction sensor 11 and the rotational speed sensor 16 for detecting the rotational speed of the rotary shaft 2 are connected to the input side of the control circuit 14. The radial electromagnet 4 1 is connected to the output side. A solenoid 15 is connected to reciprocate the axial electromagnet 51 and the rotary shaft runout suppressing bearing 13 as described above. Then, the control circuit 14 obtains the position of the rotary shaft 2 based on the detected displacements of the radial sensor 10 and the axial sensor 1 1, and compares the calculated position of the rotary shaft 2 with the target position, The excitation currents of the radial electromagnet 41 and the axial electromagnet 51 are controlled so that the rotation shaft 2 is at the target position. Furthermore, in addition to the control described above, the control circuit 14 is configured such that the rotation shaft 2 is temporarily supported by the rotation shaft runout suppression bearing 13 when the rotation of the rotation shaft 2 rises. The position of the anti-rotation bearing 1 3 is controlled.

Next, the operation of the second embodiment configured as described above will be described.

Now, when the power is turned on, the rotating shaft 2 of the magnetic bearing device is magnetically levitated by the radial electromagnets 4 1 and the axial electromagnets 5 1. The control circuit 14 receives the radial displacement of the rotary shaft 2 detected by the radial sensor 10 and the axial displacement of the rotary shaft 2 detected by the axial sensor 11. The control circuit 14 determines the radial and axial positions of the rotary shaft 2 based on the detected displacement, compares the calculated position of the rotary shaft 2 with the target position, and achieves the target position in the radial direction. Control each exciting current of electromagnet 4 1 and axial electromagnet 5 1. Since the control circuit 14 excites the solenoid 15 prior to the start of the rotation of the rotary shaft 2, the rotary shaft runout suppressing bearing 13 is in the position shown in FIG. 7 (A).

The rotating shaft 2 thus magnetically levitated to the target position is moved to the high frequency motor 3. The configuration is the same regardless of its form, for example, the rotary shaft 2 is configured as in FIG. 8 so that the lower end edge of the large diameter portion 21 of the rotary shaft 2 can contact the inner ring 71 of the protective bearing 7 Alternatively, the inner surface side of the inner ring 71 may be formed in a funnel shape. Further, the rotary shaft 2 and the protective bearing 7 may be in surface contact with each other when the rotary shaft 2 rotates. In this case, the inner surface side of the inner ring 71 of the protective bearing 7 is formed into a funnel shape so that the truncated cone portion 24 of the rotation shaft 2 is in surface contact. Next, the magnetic bearing of the second embodiment of the present invention The apparatus will be described. The magnetic bearing device of the second embodiment has substantially the same structure as the magnetic bearing device described in FIG. 1 except for the thrust bearing 5 and the protective bearing 7, so the same reference numerals are given to the same parts. And the description is omitted as appropriate.

FIG. 5 shows the configuration of the thrust bearing 5 and the protective bearing 7 in the magnetic bearing device of the second embodiment.

In this magnetic bearing device, as shown in FIG. 5, the permanent magnet 53 attached to the lower end of the rotary shaft 2 is faced downward by a frusto-conical portion 5 31 having a tapered surface that linearly changes in the axial direction. The conical portion 5 31 is configured to be supported by the rotary shaft runout suppressing bearing 13 for suppressing the runout of the rotary shaft 2 when the rotation of the rotary shaft 2 rises. Be done. The contact surface (taper surface) of the frusto-conical portion 51 1 may not only change linearly in the axial direction, but also may change in a curve in the axial direction, that is, a contact surface having a curvature.

The rotational shaft runout suppressing bearing 13 is formed of a rolling bearing or the like, and the inner surface side of the inner ring 1 31 is formed in a funnel shape so that the truncated conical portion 5 31 of the permanent magnet 5 3 can be inserted and received. Be done. Further, the rotary shaft runout suppressing bearing 1 3 is configured to be able to reciprocate between the position shown in FIG. 5 and a predetermined position lower than the position by using a solenoid (not shown) or the like. Be done.

In addition, as described above, the conical portion 5 31 is formed on the permanent magnet 5 3 side, and the rotation shaft runout suppressing bearing 13 corresponding to this is formed into a funnel shape as described later. This is to allow the smooth operation of the shaft runout suppressing bearing 13 when it ascends and descends. The scope of the claims

1. A rotary shaft, a radial bearing that magnetically supports the radial direction of the rotary shaft, a thrust bearing that magnetically supports the axial direction of the rotary shaft, the radial bearing and the thrust bearing are protected In a three-axis control type magnetic bearing device provided with

Forming the contact between the rotary shaft and the protective bearing,

A magnetic bearing device comprising: a control unit configured to control the rotating shaft and the protective bearing to be in temporary contact with each other at the time of start of rotation of the rotating shaft.

2. At the contact portion between the rotary shaft and the protective bearing, an inclined surface is formed on at least one of the rotary shaft and the protective bearing, and the rotary shaft and the protective bearing are brought into contact with each other. The magnetic bearing device according to claim 1, characterized in that: 3. A rotary shaft, a radial bearing that magnetically supports the radial direction of the rotary shaft, a thrust bearing that magnetically supports the axial direction of the rotary shaft, the radial bearing and the thrust bearing are protected In a three-axis control type magnetic bearing device provided with

A rotation shaft runout suppression bearing for suppressing the runout of the rotation shaft is provided, and the rotation shaft runout suppression bearing is controlled so as to temporarily support the rotation shaft when the rotation of the rotation shaft rises. A magnetic bearing device characterized by comprising:

When energization is performed, the motor is gradually accelerated from the stationary state and shifts to the rated speed. However, when the rotation of the rotary shaft 2 is started up, as described above, the frusto-conical portion 5 31 of the permanent magnet 5 3 integral with the rotary shaft 2 is temporarily inserted into the rotary shaft runout suppression bearing 13. Be supported. Therefore, when the rotation speed of the rotation shaft 2 reaches the vicinity of the primary resonance point (the resonance point of the rigid mode) at the rising of the rotation of the rotation shaft 2, the rotation of the rotation shaft 2 is Since the taper surface of 5 3 1 is received by the rotary shaft runout suppressing bearing 13, large swinging of the rotary shaft 2 is suppressed.

After that, when the rotational speed of the rotary shaft 2 detected by the rotational speed sensor 16 passes the primary resonance point, the control circuit 14 releases the excitation of the solenoid 15 so that the rotational shaft runout suppression bearing 1 3 is lowered from the position shown in Fig. 7 (A) to the specified position as shown in Fig. 7 (B) and is in non-contact with the frusto-conical portion 5 3 1 of the permanent magnet 53, maintaining that state Do. Thereafter, the rotary shaft 2 is controlled by the control circuit 14 so as to be at the target position.

According to the second embodiment described above, at the rising of the rotation of the rotary shaft 2, the frusto-conical portion 5 31 of the permanent magnet 5 3 integral with the rotary shaft 2 is temporarily used in the rotary shaft runout suppressing bearing 13. Was made to be bearing. Therefore, at the rising of the rotation of the rotary shaft 2, the protective bearing 7 and the rotary shaft 2 are prevented from moving together even after the resonance point, so that the steady rotation speed can be reached. Industrial applicability

As described above, according to the magnetic bearing device of the present invention, the runout of the rotary shaft is suppressed at the time of rising of the rotation of the rotary shaft, so even if the protective bearing and the rotary shaft pass the resonance point, It can be avoided to rotate and can reach a steady speed.