JPS5828059A - Magnetic fluid seal - Google Patents

Abstract

PURPOSE:To facilitate machining and assembling of a retaining member for a supply magnetic fluid by pressing and fixing a magnetic fluid containing member disposed along the inner peripheral wall of a magnet member by elastic restoring force of a beltlike elastic member mounted on the inner periphery of the magnetic fluid containing member. CONSTITUTION:A magnetic fluid containing member 13 conprising a wavy beltlike plate formed of plastics, a metallic material or the like is disposed in a space between yokes 12a, 12b along the inner peripheral wall of a magnet member 11. A beltlike elastic member 14 comprising a plate formed of plastics, a metal or the like which has enough elasticity is elastically deformed in a circle to be put along the inner periphery of the magnetic fluid containing member 13. Thus, the member 13 is pressed against the inner peripheral wall of the magnet member 11 by restoring force of the beltlike elastic member 14 to be fixed at that position.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a magnetic fluid seal that seals between a rotatable or axially movable rod and a movable rod in a portion where the rod passes through a housing of a device or the like.

This type of conventional magnetic fluid seal is shown in Figure 1.
A permanent magnet 3 having a generally cylindrical shape such as a perfect cylinder or a regular polygon is sandwiched from both sides in a hole drilled in a portion of the housing 1 through which the movable rod 2 is to pass. An annular yoke 4a having an inner diameter smaller than the inner diameter of No.3.

4b is attached, and the space between these yokes 4a l 4b is made airtight with adhesive or the like, and the annular yoke 4a.

Insert the movable rod 2 made of a ferromagnetic material such as steel while maintaining a small gap between the inner circumference of the rod 4b and the magnetic circuit as follows: magnet 3 → yoke 4a → movable rod 2 → yoke 4b → magnet 3. By holding the magnetic fluid 5 formed and filled in the minute gap between the movable rod 2 and the yokes 4a + 4b within this gap, the minute gap between the movable rod 2 and the yokes 4a and 4b is completely sealed. This is how it was done. 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, to prevent this, the inner circumference of the magnet 3 and the yoke 4a.

An impregnated material 6 impregnated with a magnetic fluid and serving as a replenishing magnetic fluid retaining member is disposed in a space formed between the magnetic fluid and the side surface of the magnetic fluid 4b, thereby providing 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, so It cannot maintain a constant shape and size for a long period of time, and may come into contact with a movable rod.Furthermore, the felt also swells during use, and its fibers separate and scatter around, causing contamination. On the other hand, instead of using a self-replenishing type that uses such an impregnated material, there are some that replenish the magnetic fluid from the outside, but the structure is complicated, the manufacturing cost is high, and regular inspections are required. There was a drawback.

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

FIG. 2 shows the main parts of an embodiment of the present invention, in which 11 is a magnet member υ such as a cylindrical permanent magnet, and 12a and 12b are annular yokes disposed closely on both sides of the magnet member 11. These magnet members 11 and yokes 12a and 12b
is sealed in the hole of the housing directly or through a ring made of other metal, similar to that shown in FIG. A movable rod is inserted,
The tiny gap is filled with magnetic fluid. Magnet member 11
is the yoke 12a.

If sufficient magnetic flux can be obtained through the minute gap between 12b and the movable rod, even if only a part of the magnetic flux is made of permanent magnets, it is not necessary to form the entire part with permanent magnets. In most cases, it may not be perfectly cylindrical, but may be approximately cylindrical, such as a regular polygonal cylinder. 13 is a band-shaped plate of plastic, metal strip, etc. formed into a wave shape.
A magnetic fluid containing member comprising a yoke 12a,
The magnet member 11 is inserted into the space between the magnet members 12b along the inner circumferential wall thereof. Reference numeral 14 denotes a band-shaped elastic member made of a plate of plastic, metal, etc. having sufficient elasticity, which is elastically deformed and inserted into the inner circumference of the magnetic fluid containing member 13 so as to be elastically deformed. In particular, an outwardly extending force always acts, pressing the member 13 against the inner circumferential wall of the magnet member 11 and fixing it in that position. As described above, since the magnetic fluid containing member 13 and the band-shaped elastic member 14 can be inserted in a rounded manner, assembly is extremely easy. Magnet member 1
A magnetic fluid (not shown) is filled between the inner circumferential wall of 1 and the band-shaped elastic member 14. The magnetic fluid is magnetic fluid containing member 1
It seeps into the space formed by 3 and is retained therein. That is, the magnetic fluid containing member 13 has the function of holding the magnetic fluid.

FIG. 6 shows the main part of another embodiment, in which a corrugated magnetic fluid containing member 13 is spirally wound in a plurality of turns, and a band-shaped elastic member 14 is elastically deformed so as to be rounded along the inner circumference thereof. This is what was charged.

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

5 to 9 show other different examples of the magnetic fluid containing member 13, FIG. 5 shows one in which grooves 15 in the width direction are arranged in a row, and FIG. 6 shows one in which grooves 16 in the longitudinal direction are arranged. A list of
7 shows a structure in which a large number of mound-shaped protrusions 17 are provided, FIG. 8 shows a structure in which a large number of concave 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 appropriately selected so that only the required amount of magnetic fluid can be retained.

The magnetic fluid held by the magnetic fluid containing member j3 passes through the gap between the band-shaped elastic member 14 and the yokes 12a, 2b, and is replenished into the minute gap between the inner periphery of the yokes 12a, 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 replenishing magnet 4, the magnetic fluid containing member forming the fluid retaining member, and the band-shaped elastic member are easy to process and assemble, and are excellent in mass production.
Further, since the band-shaped elastic member and the magnetic fluid-containing member are strongly pressed against the inner circumferential wall of the magnet member and firmly fixed, the shape will not be deformed 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 drawings]

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. 6 and 4. 5, 6, 7, and 8 are sectional views of main parts of other different embodiments, respectively.
FIG. 9 and FIG. 9 are perspective views showing other different examples of the magnetic fluid containing member. DESCRIPTION OF SYMBOLS 11... Magnet member, 12a, 12b... Yoke, 13... Magnetic fluid containing member, 14... Band-shaped elastic member half 4 figure 30

Claims (1)

[Claims] An annular yoke is provided in contact with both sides of a roughly cylindrical magnet member, and a movable yoke penetrates through the inner periphery of both yokes and a minute gap, and the minute gap is sealed with a magnetic fluid. A replenishment magnetic fluid holding member is disposed in a space formed between the magnet member and both yokes, and the magnetic fluid held by the replenishment magnetic fluid holding member is replenished into the minute gap. In the magnetic fluid seal made as follows,
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.