JPS6145098B2 - - 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
By forming a magnetic circuit as shown in the figure and holding the magnetic fluid 5 filled in the minute gap between the movable rod 2 and the yokes 4a and 4b within this gap, the gap between the movable rod 2 and the yokes 4a and 4b is completely closed. It was designed to be sealed tightly. 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 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 a magnetic fluid and serving as a replenishing magnetic fluid retaining member is provided to create 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 when assembling the yoke 4
It has to be fixed with adhesive to a and 4b, making it difficult to process.
It is difficult to assemble, the porous polymer material has poor dimensional accuracy and may come into contact with moving rods, and the felt also has poor dimensional accuracy, and its fibers separate and scatter into the surrounding area, causing contamination. It was hot. 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 type magnetic fluid seal in which the dimensional accuracy of the replenishing magnetic fluid holding member can be easily increased and assembly is simplified. will be explained in detail.

FIG. 2 shows a main part of an embodiment of the present invention, and 11
12a and 12b are annular yokes disposed closely on both sides of the magnet member 11, and the magnet member 11 and the yoke 12a,
The outer periphery of the yokes 12b is attached to the hole of the housing directly or via a ring member made of other metal in a sealed state, similar to that shown in FIG. A movable rod made of ferromagnetic material is inserted through the rod, and this minute gap is filled with magnetic fluid. Reference numeral 13 denotes a band-shaped plate made of elastic plastic, metal, etc., which is inserted into the space formed between the yokes 12a and 12b on both sides and the inner periphery of the magnet member 11. It is elastically deformed by rolling it into a circular shape along the
The strip member 13 charged in this way is applied with a force that spreads outward, presses the inner peripheral wall of the magnet member 11, and is firmly fixed at a position along the inner peripheral wall. . A gap 10 between the inner periphery of the magnet member 11 and the outermost strip plate 13, and a gap 10' formed between each strip plate are filled with magnetic fluid (not shown). The magnetic material seeps into these gaps due to its surface tension and remains there. 1
4 is a large number of small through holes arranged in the band-like plate body,
Since the magnetic fluid remains in these small holes 14, the amount of magnetic fluid that can be held increases. However, if the required amount of magnetic fluid can be retained without providing the small holes 14, the strip plate may be a smooth plate, and the number of layers may be selected appropriately.

In order to wind the elastic band plate 13 in multiple layers, it may be wound concentrically as shown in FIG. 3, or it may be wound spirally as shown in FIG.

In the example shown in FIG. 2, a large number of through holes 14 are provided in the elastic strip plate 13 in order to increase the amount of magnetic fluid that can be held, but instead of providing the through holes 14, It is also possible to have recessed holes, as shown in FIG. Horizontal groove 16
one in which a large number of small protrusions 17 are arranged on an elastic band-like plate body 13 as shown in FIG.
Alternatively, as shown in FIG. 8, the elastic band-shaped plate 13 may be formed into a wave shape. Although several examples have been shown above, the shape of the unevenness for increasing the amount of magnetic fluid retained is not limited to the above examples.

The overall length and width of the elastic band-like member can be easily and accurately processed by press working or etching, and its uneven shape can also be easily formed by the same means.

Note that the magnet member 11 does not have to be perfectly cylindrical, and may have a shape such as a regular polygon, as long as it has a generally cylindrical shape as a whole. Alternatively, it may be divided into a plurality of pieces in the circumferential direction. Yet another yoke 12
If sufficient magnetic flux can be obtained through the gap between a, 12b and the movable rod, only a part of the rod may be composed of permanent magnets, such as a sandwich-like structure in which a permanent magnet and a magnetic material are combined in the axial direction. It's okay.

As shown in FIG. 2, when small through holes 14 are provided in the elastic band-shaped plate 13, these small through holes 14,
The inner periphery of the yokes 12a, 12b passes through the gap between the strip plate 13 and the yokes 12a, 12b, or if there is no through hole, the gap between the strip plate 13 and the yokes 12a, 12b. The small gap between the rod and the movable rod is sequentially replenished.

As described above, in the present invention, since the member for holding the replenishing magnetic fluid is formed of an elastic band-like plate, the dimensional accuracy of the elastic band-like plate can be easily increased, and it is also suitable for mass production. Moreover, since it is firmly fixed to the inner circumferential wall of the magnet member by the spring force of the elastic band-shaped plate itself in the direction in which it spreads, assembly is easy and the shape does not deform due to external disturbances. Therefore, a magnetic fluid self-replenishing type magnetic fluid seal that is highly accurate and easy to manufacture can be provided at a low cost.

[Brief explanation of the drawing]

Fig. 1 is a partially cutaway perspective view of a conventional magnetic fluid seal, Fig. 2 is a perspective cross-sectional view showing the main part of an embodiment of the present invention, and Figs. 3 and 4 are elastic band-shaped plates. FIGS. 5, 6, 7, and 8 are perspective views showing different examples of winding methods when winding the body in multiple layers. It is a perspective view which shows each different example. 11... Magnet member, 12a, 12b... Yoke, 13... Elastic band-shaped plate body.

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 replenishing 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 magnetic fluid holding member is replenished into the minute gap. In the seal, the replenishing magnetic fluid retaining member elastically deforms an elastic band-like plate along the inner circumferential wall of the magnet member, and presses the inner circumferential wall of the magnet member with the restoring force against the elastic deformation, so that the inner circumferential wall A magnetic fluid seal characterized in that it is formed by a magnetic fluid seal provided so as to be fixed along.