JPS6216351B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field of the Invention The present invention relates to a magnetic fluid seal that seals between a fixed shaft and a rotating body of a device having a rotating body that rotates around a fixed shaft.

Prior Art and Problems Conventionally, this type of magnetic fluid seal, as shown in FIG. Clamp the permanent magnet 3 from both sides,
Annular yokes (hereinafter abbreviated as yokes) 4a and 4b having an outer diameter larger than the outer diameter of the permanent magnet 3 are attached, and the space between the fixed shaft 2 and the yokes 4a and 4b is made airtight using adhesive or an O-ring. , York 4
A rotating body 5 made of ferromagnetic material such as steel is inserted while maintaining a small gap between the outer circumferences of magnets a and 4b, and the permanent magnet 3→
Yoke 4a → rotating body 5 → yoke 4b → permanent magnet 3
By forming a magnetic circuit as shown in the figure and holding the magnetic fluids 6a and 6b filled in the minute gaps between the rotating body 5 and the yokes 4a and 4b, the rotating body 5 and the yokes 4a and 4b are It is designed to completely seal the gap between the two.

Since magnetic fluid is a colloidal solution in which magnetic powder is suspended in a solvent, the solvent evaporates and the sealing performance deteriorates after long-term use. Therefore, an impregnated material 7 impregnated with a magnetic fluid seal and serving as a replenishing magnetic fluid holding member is provided in the space formed between the outer periphery of the permanent magnet 3 and the side surfaces of the yokes 4a and 4b, thereby creating a self-replenishing type. . Porous sintered metal is used as the impregnating material.
Porous polymer materials, felt, etc. are used, but porous sintered metal is difficult to cut and must be fixed with adhesive to the yokes 4a and 4b during assembly, resulting in poor workability and assembly. In addition, there were drawbacks such as the adhesive part peeling off due to vibrations caused by rotation. Porous polymer materials have drawbacks such as poor dimensional accuracy and the risk of swelling and contact with rotating bodies when used for a long period of time. Felt also had drawbacks such as poor dimensional accuracy and its fibers separating and scattering around, causing contamination. On the other hand, instead of a self-replenishing type using such an impregnating material, there is also a type that replenishes magnetic fluid from the outside, but this has drawbacks such as a complicated structure, high manufacturing costs, and the need for periodic maintenance. It was hot.

Purpose of the Invention The present invention has been made to improve the above-mentioned drawbacks.The purpose of the present invention is to make it possible to easily assemble a magnetic fluid holding member for replenishment, and to prevent material change and deterioration over a long period of time. The purpose is to prevent this from occurring. Examples will be described in detail below.

Embodiment of the Invention FIG. 2 is a perspective sectional view showing essential parts of an embodiment of the invention, in which 11 is a fixed shaft, 12 is a cylindrical magnet member, and 13a and 13b are in close contact with both sides of the magnet member 12. The magnet member 12 and the yokes 13a, 13b are fixed to the fixed shaft 11 through a back plate 14 or directly in a sealed state. Also yoke 1
A rotating body (not shown) made of ferromagnetic material is inserted through the outer periphery of 3a and 13b through a minute gap similar to that shown in Fig. 1, and this minute gap is filled with magnetic fluid. be done. The magnet member 12 does not need to be made entirely of permanent magnets, as long as the magnetic flux passing through the minute gap between the yokes 13a, 13b and the rotating body is sufficient to hold the magnetic fluid in the minute gap. For example, it is possible to make a sandwich-shaped structure with a ferromagnetic material and a permanent magnet, and use only a part as a permanent magnet.
Further, the shape is not completely cylindrical, but may be a substantially cylindrical shape such as a regular polygon. Also 15
is a magnetic fluid-containing member made of a corrugated band-shaped plate of plastic, metal, etc., and is inserted into the space between the yokes 13a and 13b along the outer circumferential wall of the magnet member 12. Reference numeral 16 denotes a ring-shaped elastic body made of a band-shaped member of plastic (e.g., nylon), metal (e.g., stainless steel, phosphor bronze), etc., which has sufficient elasticity.
5 toward the center. When the annular elastic body 16 is elastically deformed and attached, the magnetic fluid containing member 15 is pressed against the outer peripheral wall of the magnet member 12,
It is firmly fixed in that position. After inserting the magnetic fluid containing member 15 in this way, the annular elastic body 1
It is extremely easy to assemble because it can be assembled by extending the parts 6 and fitting them together. When the magnetic fluid is filled between the outer circumferential wall of the magnet member 12 and the annular elastic member 16, the magnetic fluid seeps into the space formed by the magnetic fluid containing member 15 and stays there. That is, the magnetic fluid containing member 15
has the effect of holding the magnetic fluid.

FIG. 3 is a cross-sectional view of a main part of another embodiment of the present invention, in which a corrugated magnetic fluid-containing member 15 is wound in a plurality of spirals, and a ring-shaped elastic member 16 is elastically deformed along the outer circumference thereof. This is what was charged.
FIG. 4 is a sectional view of a main part of still another embodiment of the present invention, in which each magnetic fluid containing member 15 has one turn.
and ring-shaped elastic bodies 16 are inserted alternately. In FIGS. 3 and 4, the same reference numerals as in FIG. 2 represent the same parts.

5 to 9 are perspective views showing other different examples of the magnetic fluid containing member 15, and FIG.
The figure shows a case with grooves 17 arranged in the width direction, Fig. 6 shows a case with grooves 18 arranged in the length direction, Fig. 7 shows a case with a large number of mound-shaped protrusions 19, and Fig. 8 shows a case with grooves 18 arranged in a row. FIG. 9 shows one in which a large number of through holes 21 are provided. Incidentally, the magnetic fluid containing member 15 is not limited to the above-mentioned example, and may be any member as long as it has the function of holding a magnetic fluid, and felt or the like may also be used. Further, the number of layers of the magnetic fluid containing member 15 may be appropriately selected so that only the required amount of magnetic fluid can be held. The magnetic fluid-containing member 15 and the annular elastic body 16 can be manufactured extremely easily by pressing, etching, or the like.

When the magnetic fluid held in the gap between the rotating body and the yokes 13a and 13b evaporates into the outside air, leakage magnetic flux in the gap increases, and the magnetic fluid is held by the magnetic fluid-containing member due to the force of the magnetic lines of force. Replenishment magnetic fluid is drawn into the gap. Since the replenishing magnetic fluid is automatically supplied to the seal portion in this way, perfect sealing performance can be maintained for a long period of time even if the magnetic fluid evaporates.

Effects of the Invention As explained above, the present invention provides a magnetic fluid-containing member inserted along the outer peripheral wall of a magnet member,
Since the replenishing magnetic fluid retaining member is constituted by a ring-shaped elastic body that presses the magnetic fluid containing member against the outer peripheral wall of the magnet member and firmly fixes it, it will not lose its shape due to swelling or disturbance. do not have. In addition, the magnetic fluid containing member and the annular elastic body are processed,
Since assembly is easy, there is an advantage that a magnetic fluid seal that can maintain accuracy for a long period of time can be easily produced.

[Brief explanation of the drawing]

FIG. 1 is a perspective sectional view of a conventional example, FIG. 2 is a perspective sectional view of an embodiment of the present invention, FIGS. 3 and 4 are sectional views of other different embodiments of the present invention, and FIG.
9 to 9 are perspective views showing different shapes of magnetic fluid-containing members, respectively. 1 is a housing, 2 and 11 are fixed shafts, 3 is a permanent magnet, 4a, 4b, 13a, 13b are yokes, 5
is a rotating body, 6a and 6b are magnetic fluids, 7 is an impregnated material,
12 is a magnet member, 14 is a back plate, 15 is a magnetic fluid containing member, and 16 is an annular elastic body.

Claims (1)

[Scope of Claims] 1. Annular yokes are disposed facing each other in contact with both ends of a magnet member fixed to the fixed shaft, and an inner wall is formed into a cylindrical shape with a minute gap interposed between the outer periphery of the annular yoke and the oppositely disposed annular yokes. A rotating body is disposed, the minute gap is sealed with a magnetic fluid, a replenishment magnetic fluid holding member is disposed in the space formed between the magnet member and the annular yoke, and the replenishment magnetic fluid is In the magnetic fluid seal configured such that the magnetic fluid held by the holding member is supplied to the minute gap, the replenishing magnetic fluid holding member inserts the magnetic fluid containing member along the outer peripheral wall of the magnetic member. A ring-shaped elastic body is elastically deformed and inserted around the outer periphery of the magnetic fluid-containing member, and the magnetic fluid-containing member is pressed along the outer wall of the magnet member by the restoring force of the elastic body against the elastic deformation. A magnetic fluid seal characterized in that it is configured in a fixed manner. 2. The magnetic fluid seal according to claim 1, wherein the magnetic fluid containing member is a band-shaped member having an uneven surface.