JPS6145099B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a magnetic fluid seal that seals between a movable rod that rotates or moves in an axial direction and a movable rod that penetrates a housing of a device or the like.

A conventional magnetic fluid seal of this type is shown in FIG. Magnet 3 and
An annular yoke 4a which clamps this permanent magnet 3 from both sides and has an inner diameter smaller than the inner diameter of the permanent magnet 3,
4b is attached, and the space between these yokes 4a and 4b is made airtight with adhesive etc., and the annular yoke 4 is attached.
Insert the movable rod 2 made of ferromagnetic material such as steel while maintaining a small gap between the inner circumferences of magnets 3 and 4b.
Yoke 4a → Movable rod 2 → Yoke 4b → Magnet 3
The minute gap between the movable rod 2 and the yokes 4a, 4b can be closed by forming a magnetic circuit and holding the magnetic fluid 5 filled in the minute gap between the movable rod 2 and the yokes 4a, 4b. It is designed to be completely sealed. Since magnetic fluid is a colloidal solution in which magnetic powder is suspended in a solvent, the solution evaporates and the sealing performance deteriorates after long-term use. Therefore, in order to prevent this, in the space formed between the inner circumference of the magnet 3 and the side surfaces of the yokes 4a and 4b,
An impregnated material 6 impregnated with magnetic fluid and serving as a replenishing magnetic fluid holding member is provided to provide a self-replenishing type. As the impregnating material 6, porous sintered metal, porous polymer material, felt, etc. have been used.
However, porous sintered metal is not easy to cut and has to be fixed with adhesive to the yokes 4a and 4b during assembly, resulting in poor workability and assembly.Porous polymer materials gradually swell during use, making it difficult to cut over time. It is not possible to maintain a constant shape and size for a long period of time, and the felt may come into contact with movable rods.Furthermore, the felt swells during use, and its fibers separate and scatter into the surrounding area, causing contamination. On the other hand, instead of a self-replenishing type using such an impregnating material, there is also a self-replenishing type that replenishes magnetic fluid from the outside, but this has a complicated structure, increases manufacturing costs, and requires periodic inspection. There were flaws.

In view of the above points, the present invention provides a self-replenishing magnetic fluid retaining member that is easy to process and assemble, maintains a predetermined shape for a long period of time, and is manufactured at low cost. The purpose of the present invention is to provide a magnetic fluid seal that is easy to operate and maintains accuracy for a long period of time, and will be described in detail below with reference to the drawings.

FIG. 2 shows a main part of an embodiment of the present invention, and 11
is a magnet member made of a cylindrical permanent magnet, 12a,
12b is an annular yoke disposed closely on both sides of the magnet member 11;
The yokes 12a and 12b are sealed in the holes of the housing directly or through rings made of other metal, as shown in FIG. A movable rod made of ferromagnetic material is inserted through the rod, and the minute gap is filled with magnetic fluid. The magnet member 11 does not have to be made entirely of permanent magnets, but can be formed into a single side arch-shaped structure made of a ferromagnetic material and a permanent magnet, as long as sufficient magnetic flux can be obtained through the minute gap between the yokes 12a and 12b and the movable rod. Only the portion may be made of a permanent magnet, and the magnet may not be completely cylindrical, but may be approximately cylindrical, such as a regular polygonal cylinder.
13 is a magnetic fluid-containing member made of a band-shaped plate of plastic, metal, etc. formed into a wave shape,
The magnet member 11 is inserted into the space between the yokes 12a and 12b along the inner peripheral wall thereof. Reference numeral 14 denotes a band-shaped elastic member made of a plate of plastic, metal, etc. with sufficient elasticity, and the magnetic fluid containing member 13
The magnetic member 13 is elastically deformed and charged so as to be rounded around the inner circumference of the magnetic member 11. Due to the elastic deformation, a force that spreads outward is constantly exerted, pressing the member 13 against the inner circumferential wall of the magnet member 11 and fixing it in that position. do. In this way, the magnetic fluid containing member 13 and the band-shaped elastic member 14
Assembling is extremely easy since it is only necessary to insert the parts in a rounded manner. A magnetic fluid (not shown) is filled between the inner peripheral wall of the magnet member 11 and the band-shaped elastic member 14 . The magnetic fluid seeps into the space formed by the magnetic fluid containing member 13 and is retained therein. That is, the magnetic fluid containing member 13 has the function of holding the magnetic fluid.

FIG. 3 shows the main part of another embodiment, in which a corrugated magnetic fluid containing member 13 is wound in a plurality of spirals, and a band-shaped elastic member 1 is wound along the inner circumference of the magnetic fluid containing member 13.
4 was elastically deformed and charged into a round shape.

FIG. 4 shows the main part of yet another embodiment, in which one turn of each magnetic fluid containing member 13 and a band-shaped elastic member 14 are alternately inserted.

5 to 9 show the magnetic fluid containing member 13.
5 shows an example in which grooves 15 are arranged in the width direction, FIG. 6 shows an example in which grooves 16 are arranged in the longitudinal direction, and FIG.
8 shows a structure in which a large number of recessed holes 18 are provided, and FIG. 9 shows a structure in which a large number of through holes 19 are provided.

The magnetic fluid containing member 13 is not limited to the above-mentioned example, and felt may also be used, as long as it has the function of retaining the magnetic fluid. Further, the number of layers of the magnetic fluid containing member 13 is as follows:
It is chosen appropriately so that it can hold only the required amount of magnetic fluid.

The magnetic fluid held by the magnetic fluid containing member 13 is distributed between the band-shaped elastic member 14 and the yokes 12a and 1.
2b, and is replenished into the minute gap between the inner circumference of the yokes 12a and 12b and the movable rod.
The magnetic fluid containing member 13 and the band-shaped elastic member can be manufactured very easily by pressing, etching, or the like.

As explained above, the present invention is characterized in that the magnetic fluid-containing member and the band-shaped elastic member that form the replenishing magnetic fluid-holding member are easy to process and assemble, and are excellent in mass production. Since the magnetic fluid-containing member is strongly pressed against the inner circumferential wall of the magnet member and firmly fixed, it will not lose its shape due to swelling or disturbance. Therefore, a magnetic fluid seal that is easy to manufacture and assemble and can maintain accuracy for a long period of time can be provided at a low cost.

[Brief explanation of the drawing]

FIG. 1 is a partially cutaway sectional view of a conventional magnetic fluid seal, FIG. 2 is a partially cutaway perspective view of an embodiment of the present invention, and FIGS. 3 and 4. 5, 6, 7, 8, and 9 are perspective views showing other different examples of the magnetic fluid containing member. It is. DESCRIPTION OF SYMBOLS 11... Magnet member, 12a, 12b... Yoke, 13... Magnetic fluid containing member, 14... Band-shaped elastic member.

Claims (1)

[Claims] 1 An annular yoke is provided in contact with both sides of a generally cylindrical magnet member, a movable rod passes through the inner periphery of both yokes and a minute gap, the minute gap is sealed with a magnetic fluid, and the magnet member A replenishment magnetic fluid holding member is disposed in a space formed between the member and both of the yokes, and the magnetic fluid held by the replenishment magnetic fluid holding member is replenished into the minute gap. In magnetic fluid seals,
The replenishing magnetic fluid holding member is made by inserting a magnetic fluid containing member along the inner peripheral wall of the magnetic member, elastically deforming and inserting a band-shaped elastic member around the inner circumference of the magnetic fluid containing member, and A magnetic fluid seal, characterized in that the magnetic fluid containing member is pressed and fixed toward the inner circumferential wall of the magnetic member by a restoring force against elastic deformation of the band-shaped elastic member.