JPH11325074A - Bearing structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide bearing structure to provide a bearing, reducing the generation of noise even during high speed rotation, having an increased life, and high reliability, at a low cost. SOLUTION: This structure is that one set or two sets of magnetic bearings 3 and 4 to radially support the rotor 1 side of a rotation device at two support points by a magnetic force are provided, the magnetic bearings 3 and 4 are arranged such that the thrust forces thereof are exerted in both forward and opposite axial directions, and a pivot 5a to support the shaft ends of the rotor 1 is arranged on the axis of the rotor 1 with the pivot deviated in an axial direction from a neutral position where a whole thrust force exerted on the rotor 1 is balanced.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a bearing structure which can provide low noise and long life at low cost from low speed to ultra-high speed rotation in a rotating device such as a motor. The present invention relates to a bearing structure of a device requiring low noise, long life, and high reliability.

[0002]

2. Description of the Related Art As a non-contact type bearing for supporting a high-speed rotating shaft, an air dynamic pressure bearing and a magnetic bearing have been put to practical use. The former supports the radial direction by the pressure of air interposed in the gap between the shaft and the sleeve.However, in the region where the rotational speed is low, the contact method is the same as that of the contact method. Remains. On the other hand, the magnetic bearing is configured to support the radial direction or the axial direction by utilizing the attraction force or repulsion force of the magnet.

[0003]

However, a radial magnetic bearing configured to obtain a radial centripetal force by utilizing a repulsive force of a magnet generates an eccentric force in an axial direction at the same time. Alternatively, an axial magnetic bearing configured to support an axial load by using an attractive force generates an eccentric force in the radial direction at the same time, so it is difficult to support both the radial and axial directions simultaneously with a combination of only permanent magnets. However, since it is necessary to perform excitation control of one of them using an electromagnet, there is a problem that the structure becomes complicated and the cost increases.

An object of the present invention is to provide a bearing structure for realizing a low-noise, long-life, high-reliability bearing at low cost even at high speed rotation.

[0005]

In order to solve the above-mentioned problems, a radial load of a rotor is supported through one or two sets of radial magnetic bearings, and axial forces generated by the bearings are mutually offset. Or to cancel out the force in the axial direction applied from the outside.

The bearing structure according to the present invention is provided with one or two sets of magnetic bearings that radially support the rotor side of the rotating device at two support points in a non-contact manner by magnetic force in a non-contact manner. A pivot is placed on the rotor axis that acts in both axial directions, positive and negative, and is deflected in the axial direction from the neutral position where all thrust forces acting on the rotor are balanced, and receives the rotor shaft end at one point. And configure.

This bearing structure is provided with a magnetic bearing arranged so that a thrust force acts in both positive and negative axial directions, and a pivot which is deviated from its neutral position and receives the shaft end of the rotor. Since a thrust force acts on the pivot in accordance with the deviation from the position, quasi-non-contact support is possible in the vicinity of the neutral position, and rotation with low friction and low noise can be performed over the entire speed range. Therefore, there is almost no wear of the pivot bearing, and it can sufficiently withstand ultra-high-speed rotation and no noise is generated. Furthermore, since the radial direction rotates in a non-contact state, the self-centering function works,
There is a great advantage that vibration is not generated by correcting the deviation of the dynamic balance by itself. Further, the structure becomes very simple, so that a low-cost and high-performance bearing can be realized.

By providing a stopper for restricting the axial deviation of the rotor within the deviation range in which the direction of the thrust force received by the rotor is the same, the thrust can be stably supported even by the axial operation of the rotor.

Since at least one of the support points of the rotor constitutes a suction type magnetic bearing, a large radial support rigidity can be obtained, so that the bearing structure can be downsized. The bearings comprise a fixed side and a movable side by arranging the two magnets, which are magnetized in the axial direction, in opposite directions and concentrically spaced apart from each other, and oppose each other to attract both in the axial direction. By doing so, a closed magnetic path without magnetic flux leakage is formed, so that a large radial rigidity due to a high-density magnetic flux can be obtained.

At least one of the support points of the rotor forms a repulsion type magnetic bearing, so that the rotor can be inserted in the axial direction from the bearing side and easily assembled.
The degree of freedom of the configuration can be ensured. Further, the repulsion type magnetic bearing has a fixed side and a movable side which are arranged linearly and separated from each other in the same direction with the magnetization directions of a plurality of ring-shaped magnets magnetized in the axial direction. By opposing each other to repel, a strong supporting force can be easily secured by one-step collective magnetizing process.

[0011]

1 to 3 show a first embodiment of the present invention in which an axial suction type is used for a radial magnetic bearing. FIGS. 4 to 6 show a second embodiment of the present invention in which a radial magnetic bearing is used as a radial magnetic bearing. In the following drawings, a stator, an armature, a load (a fan, a polygon mirror, and the like) and the like which are naturally mounted on a stator and a rotor are omitted. Hereinafter, a specific configuration example of the present invention will be described.

FIG. 1 is a longitudinal sectional view of a bearing structure showing a first embodiment of the present invention. This bearing structure is an example in which an axial direction attracting type radial magnetic bearing is used, and a rotor 1 is rotatably supported on a stator 2 by two magnetic bearings 3 and 4. A cylindrical movable magnet 3a magnetized in the axial direction is fixed to one end of the rotor 1,
Similarly, a cylindrical fixed magnet 3b magnetized in the axial direction is opposed to the movable magnet 3a with a gap G1 so as to attract each other, and is fixed to the stator 2 to constitute the radial magnetic bearing 3.

Similarly, a movable side magnet 4a fixed to the other end of the rotor 1 and a gap G2 (G
2> G1), the radial magnetic bearing 4 is constituted by the fixed magnet 4b fixed to the stator 2 side. Also rotor 1
5b and stator 2 provided concentrically with rotating shaft 7 on the end face of
Sphere 5a placed between it and pivot receiver 5c
Constitute the pivot bearing 5. Further, the gap G2 of the radial magnetic bearing 4 has a thickness G3 (G3
The ring-shaped spacer 6 of <G2) is mounted on the end surface of the fixed-side magnet 4b.

In such a configuration, the radial magnetic bearing 3 applies a radial centripetal force to the rotor 1 and an attractive force F1 to the left in the drawing. Similarly, the radial magnetic bearing 4 applies a radial centripetal force to the rotor 1 and also applies an attractive force F2 to the right in the drawing. F1 and F2 naturally depend on the dimensions and magnetic properties of the two radial magnetic bearings 3 and 4, but if they are the same, the respective gap G
1, G2. In this configuration example, G1 is greater than F2 because G2 is larger than G1, and the difference between F1 and F2 depends on the pivot bearing 5. Here, if G2 approaches G1,
That is, near the neutral position where the thrust force is balanced, the force applied to the pivot bearing 5 approaches zero, and a quasi-non-contact state can be realized.

In the case where a stationary external force F3 such as the own weight of the rotor itself or a reaction force due to the blowing of a fan is acting in the axial direction of the rotor 1, the dimensions, magnetic characteristics, gap of the radial magnetic bearings 3, 4 Are appropriately set, the vector sum (F1 + F2 + F3) of F1, F2 and F3 can be arbitrarily reduced.

Next, the role of the spacer 6 will be described. In the case of the above-mentioned quasi-non-contact state, if there is no spacer 6, the rotor 1 moves to the right by a small thrust force from the outside and G
2 <G1. As a result, the movable-side magnet 4a and the fixed-side magnet 4b are attracted, and the rotor 1 does not return to the original position even when there is no external force. Therefore, if a spacer 6 is provided as a stopper so that G1 + G2 <2G3, even if a temporary external force acts on the rotor 1, the rotor 1 returns to its original position if the external force disappears. In the case of a fan motor or the like having a thin configuration, the two movable magnets 3a and 4a in the above configuration are formed in the same body, and three magnets are formed as one set to generate a supporting force at both ends thereof. Since it is clear that the same operation can be achieved since the support at the places can be secured, the description thereof is omitted.

FIG. 2 is a sectional view of a main part showing another structure of the bearing structure of FIG. In the following, the same members as those described above are denoted by the same reference numerals, and description thereof is omitted. In the description so far, one radial magnetic bearing has one movable-side magnet and one fixed-side magnet facing each other, but this bearing structure is composed of a plurality of cylindrical magnets. By doing so, the radial rigidity can be increased.

The magnetization directions of the two movable magnets 3a, 3aa are arranged in the back yoke 31 concentrically with the magnetization directions opposite to each other. Similarly, the magnetization directions of the two fixed magnets 3b, 3bb are set in the opposite directions. Back yoke 3 concentrically
Arrange in 2. The magnetic flux forms a loop without leakage as shown by the arrow, and the magnetic flux density in the gap increases, so that the radial rigidity increases more than the effect of the pluralization.

FIG. 3 is a sectional view of a principal part showing still another bearing structure of FIG. This bearing structure comprises a movable-side magnet 3a and a fixed-side magnet 3b magnetized in the radial direction, and constitutes an axial-direction attraction-type radial magnetic bearing. With this configuration, the object can be achieved in the same manner as the above-described configuration in which the radial magnetic bearing is formed by the magnet magnetized in the axial direction.

FIG. 4 is a longitudinal sectional view of a bearing structure according to a second embodiment of the present invention. In this bearing structure, a cylindrical movable magnet 3a magnetized in the axial direction is fixed to one end of the rotor 1, and a cylindrical fixed magnet 3b similarly magnetized in the axial direction is radially connected to the movable magnet 3a. The radial magnetic bearing 3 is concentrically fixed to the stator 2 with a gap so as to repel each other. Similarly, a radial magnet bearing 4 includes a movable magnet 4a fixed to the other end of the rotor 1 and a fixed magnet 4b fixed to the stator 2 side.
Is configured.

Further, the movable magnet 3a is moved to the left by L1 with respect to the fixed magnet 3b, and the movable magnet 4a is fixed to the fixed magnet 4b.
Is shifted to the right by L2 (L2 <L1). Further, a pivot bearing 5 is constituted by a pivot 5a provided concentrically with the rotating shaft 7 on the end surface of the rotor 1 and a pivot receiving portion 5c provided on the stator 2 side. Further, a stopper surface 8 provided on the other end of the rotor 1 and a stopper surface 9 provided on the stator 2 are separated by a gap L3. However, the range of the deviation dimensions L1 and L2 is limited to a predetermined limit at which a radial support force can be effectively obtained.

In such a configuration using a radial magnetic repulsion type radial magnetic bearing, the radial magnetic bearing 3 applies a radial centripetal force to the rotor 1 and also applies a repulsive force F1 to the left in the figure. Similarly, the radial magnetic bearing 4
Applies a radial centripetal force to the rotor 1 and a repulsive force F2 to the right in the figure. F1 and F2 naturally depend on the dimensions and magnetic characteristics of both radial magnetic bearings, but if they are the same, they depend on the axial displacements L1 and L2 of the movable magnet and the fixed magnet, and L2 <L1
Therefore, F1 exceeds F2, and the difference between F1 and F2 depends on the pivot bearing 5. Here, if L2 is brought closer to L1, that is, in the vicinity of the neutral position where the thrust force is balanced, the force applied to the pivot bearing 5 approaches zero and a quasi-non-contact state can be realized.

When a stationary external force F3 such as the own weight of the rotor itself or a reaction force due to the blowing of a fan is acting in the axial direction of the rotor 1, the dimensions and magnetic characteristics of the two radial magnetic bearings and the movable magnet By appropriately setting the positional relationship between the motor and the fixed magnet, the vector sum (F1 + F2 + F3) of F1, F2, and F3 can be arbitrarily reduced.

Next, the gap L3 between the stopper surfaces 8 and 9
Will be described. The stopper surfaces 8 and 9 are provided so that the rotor 1 does not separate from the stator 2, but in the quasi-non-contact state described above, the rotor 1 moves rightward with a slight thrust force from the outside, and L2 <L1. As a result, the stopper surface 8 comes into contact with the stopper surface 9, and the rotor 1 does not return to the original position even when the external force is lost. Therefore, if L3 is set so that L1−L2> 2L3, even if a temporary external force acts on the rotor 1, the rotor 1 returns to the original position again when the external force disappears.

FIG. 5 is a sectional view of a main part showing another structure of the bearing structure of FIG. This bearing structure is composed of two cylindrical movable magnets 3a, 3aa which are magnetized in the axial direction and are provided on the rotor 1 at an interval, and two cylindrical fixed magnets 3b, 3bb which are also provided on the stator. And In this way, by constituting each with a plurality of cylindrical magnets, in comparison with the above-described radial magnetic bearing in which one movable-side magnet and one fixed-side magnet are arranged concentrically, one step is achieved. Radial rigidity can be increased by a large magnetic force due to simple magnetization processing.

FIG. 6 is a sectional view of a principal part showing still another bearing structure of FIG. This bearing structure constitutes a radial repulsion type radial magnetic bearing including a movable magnet 3a and a fixed magnet 3b magnetized in the radial direction. With the configuration using the magnet magnetized in the radial direction, the radial magnetic bearing can achieve the object similarly to the configuration using the magnet magnetized in the axial direction. The repulsion type magnetic bearing is configured such that the inner diameter on the stator side is larger than the maximum diameter of the rotor, so that the rotor can be inserted from the bearing side. Can be secured.

FIG. 7 is a longitudinal sectional view of a bearing structure according to a third embodiment of the present invention, and FIG. 8 is a view showing a state of deflection by the bearing structure. In this bearing structure, instead of the spacer of the bearing structure of FIG. 1, pivot bearings 5 and 5 are formed at both shaft ends of a rotor 1 that supports a rotating mirror 11 and the like.
A gap having a length L is formed in the direction. This gap of length L is
A neutral position where the thrust forces of the two magnetic bearings 3 and 4 are balanced at a substantially intermediate position is set as small as possible within a range that can absorb the dimensional difference due to assembling and thermal expansion of each component member. With the above configuration, the forces acting on the pivot bearings 5, 5 can be minimized in any case, so that a quasi-non-contact state can be realized and the rotor 1
, The configuration accuracy in the direction of the axis 7 can be ensured. In the above description, the same kind is used for the two sets of radial magnetic bearings. However, it is needless to say that any kind of combination is possible.

[0028]

The bearing structure according to the present invention has the following effects. This bearing structure is provided with a magnetic bearing arranged so that the thrust force acts in both the positive and negative axial directions, and a pivot that is deviated from the neutral position and receives the shaft end of the rotor. Since a thrust force acts on the pivot in accordance with the deviation, quasi-non-contact support is possible in the vicinity of the neutral position, and rotation with low wear and low noise can be performed over the entire speed range. Therefore, there is almost no wear of the pivot bearing, and it can sufficiently withstand ultra-high-speed rotation and no noise is generated. Furthermore, since the radial direction rotates in a non-contact state, the self-aligning action works, and there is a great advantage that the deviation of the dynamic balance is corrected by itself and no vibration occurs. Further, the structure becomes very simple, so that a low-cost and high-performance bearing can be realized.

By providing a stopper for restricting the axial deviation of the rotor within the deviation range in which the direction of the thrust force received by the rotor is the same, the thrust can be stably supported even by the axial operation of the rotor.

Since at least one of the support points of the rotor forms a magnetic attracting type bearing, a large radial support rigidity can be obtained, so that the size of the bearing can be reduced. The bearings comprise a fixed side and a movable side by arranging the two magnets, which are magnetized in the axial direction, in opposite directions and concentrically spaced apart from each other, and oppose each other to attract both in the axial direction. By doing so, a closed magnetic path free of magnetic flux leakage is formed, so that a large radial rigidity due to high-density magnetic flux can be obtained.

At least one of the support points of the rotor forms a repulsion type magnetic bearing, so that the rotor can be inserted in the axial direction from the bearing side and easily assembled.
The degree of freedom of the configuration can be ensured. Further, the repulsion type magnetic bearing has a fixed side and a movable side which are arranged linearly and separated from each other in the same direction with the magnetization directions of a plurality of ring-shaped magnets magnetized in the axial direction. By opposing each other to repel, a strong supporting force can be easily secured by one-step collective magnetizing process.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of a bearing structure according to a first embodiment of the present invention.

FIG. 2 is a sectional view of a main part showing another configuration of the bearing structure of FIG. 1;

FIG. 3 is a sectional view of a main part showing still another bearing structure of FIG. 2;

FIG. 4 is a longitudinal sectional view of a bearing structure according to a second embodiment of the present invention.

FIG. 5 is a sectional view of a main part showing another configuration of the bearing structure of FIG. 4;

FIG. 6 is a sectional view of a main part showing still another bearing structure of FIG. 5;

FIG. 7 is a longitudinal sectional view of a bearing structure according to a third embodiment of the present invention.

FIG. 8 is a longitudinal sectional view showing a state of deflection by the bearing structure of FIG. 7;

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 rotor 2 stator 3 radial magnetic bearing at one end 3a, 3aa movable magnet at one end 3b, 3bb fixed magnet at one end 4 radial magnetic bearing at the other end 4a movable magnet at the other end 4b at the other end Fixed magnet 5 Pivot bearing 5a Pivot 7 Rotation axis (axis)

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[Procedure amendment]

[Submission date] June 17, 1999

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0024

[Correction method] Change

[Correction contents]

Next, the gap L3 between the stopper surfaces 8 and 9
Will be described. The stopper surfaces 8 and 9 are provided so that the rotor 1 does not separate from the stator 2, but in the quasi-non-contact state described above, the rotor 1 moves rightward by a small thrust force from the outside and L1 <L2 . As a result, the stopper surface 8 comes into contact with the stopper surface 9, and the rotor 1 does not return to the original position even when the external force is lost. Therefore, if L3 is set so that L1−L2> 2L3, even if a temporary external force acts on the rotor 1, the rotor 1 returns to the original position again when the external force disappears.

Claims (7)

[Claims] 1. One or two sets of magnetic bearings for radially supporting the rotor side of a rotating device in two contact points in a non-contact manner by magnetic force in a non-contact manner are provided. Bearing which is arranged so as to act in the axial direction, and is deflected in the axial direction from a neutral position where all thrust forces acting on the rotor are balanced, and a pivot which receives the shaft end of the rotor at one point is arranged on the axis of the rotor. Construction. 2. A stopper for restricting axial displacement of the rotor in a displacement range in which the direction of the thrust force received by the rotor is the same.
The bearing structure described. 3. The bearing structure according to claim 1, wherein at least one of the support points of the rotor forms a magnetic bearing of an attraction type. 4. The attraction-type magnetic bearing comprises a fixed side and a movable side by concentrically spaced apart from each other by inverting the magnetization directions of two ring-shaped magnets magnetized in the axial direction, 4. The bearing structure according to claim 3, wherein both are opposed to each other so as to be sucked in the axial direction. 5. The bearing structure according to claim 1, wherein at least one of the support points of the rotor forms a repulsion type magnetic bearing. 6. The repulsion type magnetic bearing comprises a plurality of ring-shaped magnets magnetized in the axial direction having the same magnetization direction and being linearly separated from each other to constitute a fixed side and a movable side, respectively. 6. The bearing structure according to claim 5, wherein the bearing structures oppose each other so as to repel in a radial direction. 7. The bearing structure according to claim 1, wherein pivots are provided at both ends of the rotor, and a neutral position where the total thrust force is balanced is disposed at a substantially intermediate position of a gap in the axial direction. .