JP2542227Y2 - Magnetic fluid bearing - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial application field) The present invention relates to a plain bearing type magnetic fluid bearing using a magnetic fluid as a lubricant.

(Prior Art) Conventional magnetic fluid bearings include, for example, those shown in FIG. This magnetic fluid bearing has a shaft 101 made of a non-magnetic material or a magnetic material to which a disk-shaped flange 100, which is a permanent magnet that is unipolarly magnetized in the axial direction, is fixed. and a magnetic fluid 103 interposed in the small gap a.
It is comprised by these. Here, the micro gap a has a magnetic field gradient such that the magnetic field becomes larger as it approaches the end face 100a of the flange 100, which is a permanent magnet, and the magnetic fluid 103 is attracted to the flange 100 by the magnetic field gradient. (Lifting force) acts, and the shaft 101 is supported.

(Problems to be Solved by the Invention) However, the above-described conventional magnetic fluid bearing has the following problems. That is, since the flange 100, which is a permanent magnet, is unipolarly magnetized in the axial direction, the average magnetic field gradient in the axial direction is large, but the average magnetic field gradient in the radial and circumferential directions is small, and only near the end of the flange 100. Increases the magnetic field gradient in the radial direction. Therefore, there is a problem that the magnetic pressure does not become too large and the load capacity is small. In addition, since the collar 100, which is a permanent magnet, is unipolarly magnetized in the axial direction, there is a problem that a large amount of magnetic flux leaks to the outside and a magnetic disturbance is given to the outside.

This invention is intended to solve the above-mentioned problem, and has an object to provide a magnetic fluid bearing which can form a large average magnetic field gradient also in a radial direction and a circumferential direction of a flange of a shaft and has a small leakage magnetic flux to the outside. And

(Means for Solving the Problems) In order to achieve the above object, the present invention is directed to a shaft having a disk-shaped flange which is a permanent magnet, and a non-magnetic shaft arranged with a minute gap between the outer peripheral surface and both end surfaces of the flange. In a magnetic fluid bearing composed of a housing made of a material and a magnetic fluid interposed in the minute gap, multi-pole magnetization is performed in the axial direction such that the magnetic poles adjacent to each other in the radial direction and the circumferential direction have different polarities. Characterized in that it is a permanent magnet.

Further, the shaft includes a shaft having a disk-shaped flange which is a non-magnetic material, a housing of a permanent magnet arranged with a minute gap between the outer peripheral surface and both end surfaces of the flange, and a magnetic fluid interposed in the minute gap. In the magnetic fluid bearing, the housing may be a permanent magnet multi-polarized in an axial direction on a surface facing both end surfaces of the flange so that adjacent magnetic poles in a radial direction and a circumferential direction are different from each other. Features.

(Effect) The present invention based on the above configuration is characterized in that, when a permanent magnet magnetized in the axial direction is used as a shaft flange or housing so that adjacent magnetic poles in the radial direction and the circumferential direction are different from each other, a flange is formed. Since a large magnetic field gradient is formed in the radial direction and the circumferential direction in addition to the magnetic field gradient in the axial direction on the outer circumference of the housing or the inner circumference of the housing, the generated magnetic pressure increases. Therefore, the load capacity increases.

In addition, the flange or housing made of a permanent magnet is multipolar magnetized so that adjacent magnetic poles are different from each other, so that the main magnetic flux flows between the adjacent different poles, and the leakage magnetic flux to the outside is reduced. .

(Example) Next, this invention is demonstrated based on an accompanying drawing.

 1 and 2 show a first embodiment.

In the figure, reference numeral 1 denotes a shaft, and the shaft 1 has a disk-shaped flange 2 which is a permanent magnet. Further, the outer peripheral surface 3 and both end surfaces 4 of the flange 2 are arranged with a small gap A with respect to the annular groove 6 of the housing 5 made of a non-magnetic material, and a magnetic fluid 7 is interposed in the small gap A. Let me do it.

The flange 2 is multipolarly magnetized in the axial direction such that adjacent magnetic poles in the radial direction and the circumferential direction have different polarities. That is, the magnetic poles are magnetized so that the paired north and south poles are in the axial direction, and the magnetic poles adjacent to each other in the radial direction and the circumferential direction are different in polarity. This Tsuba 2
Is magnetized to a single one in the illustrated embodiment, but is magnetized so that the paired north and south poles are in the axial direction, and the adjacent magnetic poles in the circumferential direction are different from each other. A plurality of ring-shaped permanent magnets (not shown) having multi-polarized magnets in the axial direction having different diameters are prepared, and these are arranged closely so that magnetic poles adjacent in the radial direction have different poles. May be configured.

As described above, the flange 2 is multipolarly magnetized in the axial direction so that the magnetic poles adjacent in the radial direction and the circumferential direction are different from each other.
Is used, a large magnetic field gradient is formed in the radial direction and the circumferential direction in addition to the axial magnetic field gradient. Therefore, the magnetic pressure acting on the housing 5 by the magnetic fluid 7 increases, and the load capacity supporting the shaft 1 increases. In addition, since the flange 2 is constituted by the multi-polarized permanent magnets, the main magnetic flux flows between adjacent different poles. Therefore, an effect is obtained that the leakage magnetic flux to the outside is small and magnetic disturbance can be prevented.

Next, FIGS. 3 and 4 show a second embodiment of the present invention.
In this embodiment, both end surfaces 6a of an annular groove 6 of a housing 5 which are opposed to both end surfaces 4 and an outer peripheral surface 3 of a flange 2 made of a non-magnetic material via a small gap A are adjacent to each other in a radial direction and a circumferential direction. The magnetic poles are constituted by permanent magnets that are multipolar magnetized in the axial direction so that the magnetic poles are different from each other. The rest is configured similarly to the first embodiment. Although a single housing 5 made of this permanent magnet is used in the illustrated example, it is constituted by closely arranging a plurality of annular permanent magnets having different diameters as in the first embodiment. May be. Also, the entire housing 5 does not necessarily need to be a permanent magnet,
Only the portion facing the both end surfaces 4 of the flange 2 made of a non-magnetic material may be a permanent magnet multi-polarized in the axial direction, and the other outer portion may be made of a non-magnetic material or a magnetic material. The operation and effect of the second embodiment are the same as those of the first embodiment (except that the magnetic pressure by the magnetic fluid 7 acts on the flange 2).
Therefore, the description is omitted.

In each of the first and second embodiments described above, the permanent magnets in which the rows of magnetic poles adjacent in the radial direction are radial in the radial direction are used. However, the permanent magnets are not necessarily radial, and are twisted in the circumferential direction. (Not shown) or meandering (not shown).

In the first and second embodiments described above, the permanent magnets are multipolar magnetized so that the number of poles is 5 in the radial direction and 24 in the circumferential direction. However, the number of magnetic poles is not limited to this. is not.

(Effects of the Invention) Since the invention is configured as described above, a large magnetic field gradient is formed in the radial and circumferential directions in addition to the axial magnetic field gradient, and the generated magnetic pressure increases. Therefore, the load capacity increases. In addition, since the main magnetic flux flows between adjacent different poles, the leakage magnetic flux to the outside decreases,
Magnetic disturbance can be prevented.

[Brief description of the drawings]

1 is a sectional view showing a first embodiment of a magnetic fluid bearing according to the present invention, FIG. 2 is a sectional view taken along line A'-A 'of FIG. 1, and FIG. 3 is a magnetic fluid bearing according to the present invention. FIG. 4 is a sectional view taken along the line BB of FIG. 2, and FIG. 5 is a sectional view showing a conventional magnetic flux bearing. DESCRIPTION OF SYMBOLS 1... Shaft 2... Flange 3... Outer periphery of flange 4. Both ends of flange 5. Housing 6... Annular groove 6 a. Fluid A: minute gap

Claims (2)

(57) [Scope of request for utility model registration] A shaft having a disk-shaped flange which is a permanent magnet;
In a magnetic fluid bearing comprising a housing made of a non-magnetic material and a magnetic fluid interposed in the minute gap with the outer peripheral surface and both end surfaces of the flange interposed therebetween with a minute gap, the flange has a radial direction and a circumferential direction. A magnetic fluid bearing, wherein the magnetic fluid bearing is a permanent magnet which is magnetized in the axial direction so that adjacent magnetic poles are different from each other. 2. A shaft having a disk-shaped flange made of a non-magnetic material,
In a magnetic fluid bearing comprising a housing of a permanent magnet disposed with a minute gap between the outer peripheral surface and both end surfaces of the flange, and a magnetic fluid interposed in the minute gap, the housing is adjacent in a radial direction and a circumferential direction. A magnetic fluid bearing, wherein the magnetic fluid bearing is a permanent magnet that is multipolarly magnetized in the axial direction on a surface facing both end surfaces of the flange so that matching magnetic poles are different from each other.