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Magnetic fluid seal

Imported: 24 Feb '17 | Published: 06 Jan '04

Hiroshi Anzai

USPTO - Utility Patents

Abstract

A magnetic fluid seal with an excellent quality for reduction of leak of magnetic fluid. Among the projections of the pole pieces, the projections, that are nearest to the permanent magnet, are placed at positions intruding into the permanent magnet sides to hold the magnetic fluid in a space between the projections and the surface of the shaft.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic construction diagram showing a usage state of a magnetic fluid seal according to the first embodiment;

FIG. 2 is a schematic construction diagram showing a usage state of a magnetic fluid seal according to the second embodiment;

FIG. 3 is a schematic construction diagram showing a usage state of a magnetic fluid seal according to the third embodiment;

FIG. 4 is a schematic construction diagram showing a usage state of a magnetic fluid seal according to the fourth embodiment;

FIG. 5 is a schematic construction diagram showing a usage state of a magnetic fluid seal according to a conventional technique; and

FIG. 6 is a schematic construction diagram showing a usage state of a magnetic fluid seal according to another conventional technique.

Claims

1. A magnetic fluid seal for sealing a circular space between a shaft and a housing, comprising:

2. The magnetic fluid seal according to claim 1, wherein the holding projections, which are farthest from the magnetic force generating member among the holding projections of said magnetic pole members, are provided at positions that are placed inward from end surfaces in the shaft extending direction of main bodies of the magnetic pole members, and a distance between the shaft surface and wall surfaces, which oppose the shaft surface and exist at positions placed outward from the holding projections that are farthest from the magnetic force generating member, is longer than a distance from tips of the holding projections to the shaft surface and is shorter than heights of the holding projections.

3. The magnetic fluid seal according to claim 2, wherein the wall surfaces opposing said shaft surface are each formed as a tapered surface whose distance to the shaft surface is gradually reduced as directing from an outer side to an inner side.

4. A magnetic fluid seal for sealing a circular space between a shaft and a housing, comprising:

5. The magnetic fluid seal according to claim 4, wherein an intercepting seal for intercepting a space between said magnetic force generating member and a housing interior surface is provided between the holding projections that are nearest to said magnetic force generating member.

6. The magnetic fluid seal according to claim 4, wherein the holding projections, which are farthest from the magnetic force generating member among the holding projections of said magnetic pole members, are provided at positions that are placed inward from end surfaces in the shaft extending direction of main bodies of the magnetic pole members, and a distance between the housing interior surface and wall surfaces, which oppose the housing surface and exist at positions placed outward from the holding projections that are farthest from the magnetic force generating member, is longer than a distance from tips of the holding projections to the housing interior surface and is shorter than heights of the holding projections.

7. The magnetic fluid seal according to claim 6, wherein the wall surfaces opposing said housing interior surface are each formed as a tapered surface whose distance to the housing interior surface is gradually reduced as directing from an outer side to an inner side.

8. The magnetic fluid seal according to claim 7, wherein a taper angle of each of the wall surfaces opposing said housing interior surface is set at 45° or less.

9. The magnetic fluid seal according to claim 8, wherein the wall surfaces opposing said housing interior surface are each formed so that the taper angle is set in a range of from 5° to 30°.

10. A magnetic fluid seal for sealing a circular space between a shaft and a housing, comprising:

11. The magnetic fluid seal according to claim 10, wherein the wall surfaces opposing said shaft surface are each formed as a tapered surface whose distance to the shaft surface is gradually reduced as directing from an outer side to an inner side.