JP2589522Y2 - Magnetic bearing - Google Patents

Description

[Detailed description of the invention]

[0001]

BACKGROUND OF THE INVENTION This invention relates to an improvement in a radial bearing utilizing a repulsive force of a permanent magnet.

[0002]

2. Description of the Related Art Radial magnetic bearings utilizing magnetic force are:
Since the bearings are supported in a non-contact manner, they have characteristics such as low sliding friction of the bearing, suitable for high-speed rotation, and long life. In particular, radial bearings utilizing the repulsive force of permanent magnets are widely used because of their very simple structure. This bearing is generally provided with annular permanent magnets having a rectangular cross section on the stationary side and the rotating side. The fixed and rotating magnets are magnetized in the axial direction, respectively, and the opposed magnets on the fixed and rotating sides are arranged to have the same polarity. It can be supported in a non-contact manner (for example, Japanese Utility Model Application Laid-Open No. 60-102522).

[0003]

However, in the prior art, since the ring-shaped permanent magnet is used as a ring or simply divided and used in a fan shape, it is not easy to manufacture it with high accuracy, or the diameter is small. There is a problem that a magnet having a shape suitable for each different one must be made. In particular, when the diameter of the ring is large, the thickness of the magnet is thinner than the diameter, so the strength is reduced, and the magnet is easily broken due to mishandling in the assembling process, and the production yield is poor. Was.

[0004]

In order to solve such a problem, the present invention comprises an annular stator magnet which is magnetized in the axial direction on a fixed side, and a rotating side inside the stator magnet. Has an annular rotor magnet magnetized in the axial direction,
In the magnetic bearing, the two magnets radially opposed to each other via an air gap are concentrically arranged so as to have the same polarity,
The cross section is a convex shape, and projections are formed on the left and right, and a plurality of prismatic stator magnet pieces forming the stator magnet are used, and one of the stator magnet pieces is fitted on the outer peripheral side of the bottom of the annular notch. A fixed-side housing having an annular groove formed so as to fit therewith, and an annular notch formed on the outer periphery of one end in the axial direction so that the other protrusion of the stator magnet piece fits therein. A holding ring fitted into the cutout portion of the fixed housing; a prism-shaped rotor magnet piece forming a rotor magnet by using a plurality of projections having a convex cross-section and forming a rotor magnet; and an annular step portion A stepped rotation shaft having an annular groove formed so that one of the protrusions of the rotor magnet piece is fitted on the inner peripheral side of the bottom of the rotor magnet piece, and the other end of the rotor magnet piece on the inner circumference at one axial end. Form an annular notch so that the protrusion fits, Peripheral is characterized in that and a retaining ring fitted to the stepped portion of the rotary shaft. Further, the length of the inner side of the side of the stator magnet is shorter than the length of the outer side thereof, and the length of the outer side of the side of the rotor magnet piece is longer than the length of the inner side. ,
It is characterized in that the fixed side is used as a rotating side and the rotating side is used as a fixed side.

[0005]

With such a configuration, the divided permanent magnet pieces are firmly fixed to the rotating side and the fixed side housings by the holding ring.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a partial sectional view of a radial bearing to which the present invention is applied. FIG. 2 is a cross-sectional view taken along the line AA ′ of FIG. 3A and 3B are diagrams showing the shapes of the permanent magnet pieces of the rotor and the stator, wherein FIG. 3A is a side view and FIG. 3B is a sectional view. In FIG. 1, reference numeral 1 denotes a rotating shaft, which is a stepped shaft having an annular groove 11 in a step portion at the shaft end. Numeral 2 denotes a prism-shaped rotor magnet piece, as shown in the cross-sectional view of FIG. 11 is slightly smaller than the depth. The magnetizing direction of the rotor magnet piece 2 is (b)
The cross-sectional view of FIG. Reference numeral 3 denotes a cylindrical pressing ring, and an annular cutout portion 31 having the same width as the width of the groove 11 and slightly deeper than the height of the projection 22 is provided on the inner diameter side at one end in the axial direction.
Are formed. As shown in FIG. 2, a large number (16 in the figure) of the rotor magnet pieces 2 are arranged on the step portion of the rotating shaft 1. One of the left and right protrusions 22 provided on the rotor magnet piece 2 is fitted in the groove 11, and the adjacent rotor magnet pieces 2 have the same magnetization direction. Adjacent rotor magnet pieces 2
Are in close contact with each other at the corners on the inner diameter side. The other stepped portion 21 provided on the rotor magnet piece 2 is fitted into the notch 31 of the holding ring 3. Also, presser ring 3
Are tightly fitted to the step portion of the rotating shaft 1 and the rotor magnet pieces 2
Are firmly fixed in the radial and axial directions. The rotation-side magnetic pole is configured as described above. Reference numeral 4 denotes a cylindrical stationary housing, which is provided with an annular notch 42 on the inner diameter side at one end in the axial direction, and an annular groove 41 at the bottom thereof.
Are formed. Reference numeral 5 denotes a prism-shaped stator magnet piece. As shown in the cross-sectional view of FIG.
2 are provided to form a stepped portion 51, and the height of the projection 52 is slightly smaller than the depth of the groove 41. The magnetizing direction of the stator magnet pieces 5 is the left-right direction in the cross-sectional view of FIG. Reference numeral 6 denotes a cylindrical pressing ring, which has an annular notch 61 formed on the outer diameter side at one end in the axial direction and having the same width as the width of the groove 41 and slightly deeper than the height of the projection 52. As shown in FIG. 2, a large number (16 in the figure) of the stator magnet pieces 5 are arranged in the notch 42. One of the projections 52 provided on the stator magnet piece 5 is fitted in the groove 41, and the adjacent stator magnet pieces 5 have the same magnetization direction. The adjacent stator magnet pieces 5 are in close contact with each other at the corners on the inner diameter side. The other stepped portion 51 provided on the stator magnet piece 5 is provided with the notch 6 of the holding ring 6.
1 is fitted. The holding ring 6 is tightly fitted in the notch 42 of the fixed housing 4, and the stator magnet piece 5 is firmly fixed in the radial direction and the axial direction. The fixed magnetic pole is configured as described above. Since the cross-sectional shapes of the rotor magnet piece 2 and the stator magnet piece 5 are prismatic, the adjacent stator magnet pieces 5 are located between the adjacent rotor magnet pieces 2 on the rotating magnetic pole surface and the adjacent stator magnet pieces 5 on the fixed magnetic pole back face.
There is a gap between them. Since the outer circumference of the rotating magnetic pole and the inner circumference of the fixed magnetic pole are polygonal, the size of the air gap cannot be said to be uniform, and the magnetic flux becomes non-uniform, which may cause cogging. However, the air gap can be made larger than the length of each of the magnet pieces 2 and 5, or the number of magnets can be increased by increasing the number of divisions so that the number of magnets can be made uniform, so that there is no practical problem. . FIGS. 4 and 5 are views showing the shape of the permanent magnet piece of the second embodiment. FIG. 4 is a drawing of the rotor magnet piece 2 and FIG. (A) is a side view and (b) is a cross-sectional view. In these figures, the difference from FIG. 3 of the first embodiment is that the left and right end faces in the side view (a) are inclined to form the tapered portions 23 and 53, whereby the side faces become trapezoidal. I have. With such a shape, by appropriately setting the inclination angle, when the rotor magnet pieces 2 are assembled in an annular shape, the tapered portions 23 of the adjacent rotor magnet pieces 2 can be brought into close contact with each other. The same applies to the stator magnet pieces 5, and when assembled into an annular shape, the tapered portions 53 of the adjacent stator magnet pieces 5 can be brought into close contact with each other. By doing so, the magnetomotive force can be increased and the structural strength can be increased. In the above two embodiments, the inner rotor type rotating shaft in which the rotor is arranged inside the stator is shown, but it is obvious that the rotor and the stator may be exchanged to form the outer rotor type. Further, the case where the stator magnet pieces 5 and the rotor magnet pieces 2 are located at the same position in the axial direction is shown. However, the arrangement may be such that they are axially shifted from each other to generate a repulsive force in the axial direction. Never. With the above-described configuration, it is possible to support in a non-contact manner in the radial direction by the magnetic repulsion, and to smoothly rotate the rotating shaft without a large loss.

[0007]

As described above, according to the present invention, the radial bearing is assembled using magnet pieces having a simple shape, so that the manufacture and assembly of the magnet are facilitated and the yield is improved. In addition, it is easy to accommodate different diameters,
A radial bearing having a large diameter can be easily obtained without being limited by the diameter of the annular magnet. Therefore, it has been difficult to apply a permanent magnet type magnetic bearing to a rotating machine having a large diameter so far, but the present invention makes it easier to apply the magnetic bearing, and there is a large contribution to the industry.

[Brief description of the drawings]

FIG. 1 is a partial sectional view showing an embodiment of the present invention.

FIG. 2 is a cross-sectional view taken along the line A-A ′ of FIG. 1;

3A and 3B are diagrams showing the shape of a permanent magnet piece, wherein FIG. 3A is a side view, and FIG.

FIGS. 4A and 4B are diagrams showing a shape of a rotor magnet piece of a second embodiment, wherein FIG. 4A is a side view and FIG.

5A and 5B are diagrams showing the shape of a stator magnet piece according to a second embodiment, wherein FIG. 5A is a side view, and FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Rotation shaft 11, 41 Groove 2 Rotor magnet piece 21, 51 Stepped part 22, 52 Projection 23, 53 Tapered part 24, 54 Short side 25, 55 Long side 3 Pressing ring 31, 61 Notch part 4 Fixed side housing 5 Stator magnet piece 6 Holding ring

Claims (3)

(57) [Scope of request for utility model registration] 1. A fixed side is provided with an annular stator magnet which is magnetized in the axial direction, and a rotating side inside the stator magnet is provided with an annular rotor magnet which is magnetized in the axial direction. In the magnetic bearing, wherein the two magnets radially opposed to each other via a gap are concentrically arranged so as to have the same polarity, a cross-section is formed in a convex shape, and projections are formed on the left and right, and a plurality of the stator magnets are used. A stator magnet piece having a prismatic shape, a fixed side housing having an annular groove formed on the bottom outer peripheral side of the annular notch so that one of the protrusions of the stator magnet piece fits therein, and an outer periphery at one axial end, Forming an annular notch so that the other protrusion of the stator magnet piece fits,
A press ring whose outer periphery fits into the notch of the fixed side housing; a prism-shaped rotor magnet piece that forms a rotor magnet by using a plurality of protrusions having a convex cross section and forming a rotor magnet; A stepped rotating shaft having an annular groove formed on the inner peripheral side of the bottom of the step so as to fit one of the protrusions of the rotor magnet piece; Forming an annular notch so that one of the protrusions fits,
A pressure ring having an inner periphery fitted to the step portion of the rotary shaft. Wherein the outer of said stator magnet pieces is shorter than the length of the outer peripheral side length of the inner periphery of the side surface, the rotor magnet pieces side surface
2. The magnetic bearing according to claim 1, wherein the length on the circumferential side is longer than the length on the inner circumferential side. 3. The magnetic bearing according to claim 1, wherein the fixed side is used as a rotating side, and the rotating side is used as a fixed side.