JPS5891967A - Magnetic fluid seal - Google Patents

Abstract

PURPOSE:To obtain a magnetic fluid holding member for supply easy to be assembled by arranging wire held by the restoring force against its own elastic deformation alongside the inner wall of a magnet member. CONSTITUTION:In a hollow space provided between the inner circumference of a magnet member 11 and yokes 12a and 12b on both sides, an elastic wire 13 wound up several times is fitted. Gaps 14 between the inner circumference of the magnet member 11 and the wire 13 and gaps 15 between wire rods when wound up in multiple layers, are filled with magnetic fluid 16 for supply.

Description

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

The conventional Muno@0 magnetic fluid seal is as shown in Figure 1.
A completely cylindrical or polygonal permanent magnet 5, such as a completely cylindrical or polygonal one, is inserted into the hole drilled in the part of the housing 1 where the movable rod 2 is to pass, and the permanent magnet 3 is sandwiched from both sides. Annular l- having an inner diameter smaller than the inner diameter
(hereinafter abbreviated as yoke) 4a and 46 are installed, and these eyes are 4g.

4b is airtight with an adhesive cape, and an annular cape is used.
Insert the movable rod 2 made of a ferromagnetic material such as steel while maintaining a small gap with the inner circumference of the permanent magnet 3 and the permanent magnet 3.
48 → Movable rod 2 → Magnetic circuit 4b → Permanent magnet 5.
By holding the magnetic fluid 5 filled in the minute gap between the movable rod 2 and the eyes 4a, 4 in this gap,
There is also a model O'c that completely seals the space between it and 6.

Since magnetic fluid is a colloidal solution in which magnetic powder is suspended in a solvent, the solvent evaporates during long-term use and the performance of the magnetic fluid deteriorates. Therefore, the inner circumference of the permanent magnet 3 and the uniformity 4a, 4
An impregnated material 6 impregnated with magnetic fluid and serving as a replenishing magnetic fluid retaining member is disposed in the space formed between the side surface of the magnetic fluid and the side surface of b, thereby making it self-replenishing. Porous sintered metals, porous polymer materials, felt, etc. are used as impregnating materials.
Porous sintered metal is difficult to cut, and must be fixed with adhesive to the seals 4a and 4b during assembly, resulting in poor workability and poor dimensional accuracy. When used for a long period of time, there is a risk that it will swell and come into contact with the movable rod, and felt has poor dimensional accuracy and its fibers will separate and scatter around the circumference 11, causing contamination. . On the other hand, there are self-replenishing models using such impregnated materials that replenish magnetic fluid from the outside, but these have complicated structures, high manufacturing costs, and require periodic inspection. There were drawbacks.

The present invention is an attempt to improve the above-mentioned drawbacks, and its purpose is to make it possible to easily assemble a replenishing magnetic fluid holding member, and to make it durable for a long period of time.

The goal is to prevent material deterioration and deformation over time. Examples will be described in detail below.

FIG. 2 is a perspective sectional view showing a main part of an embodiment of the present invention, in which 11 is a cylindrical magnet member, 12G, 12 & are annular yokes disposed closely on both sides of the magnet member 110. The outer peripheries of the magnet member 11 and the yokes 128, 126 are sealed in the holes of the housing directly or through other metal ring members, similar to those shown in FIG. A movable rod made of ferromagnetic material passes through the inner periphery of the yokes 12a and 126 through a minute gap, and this minute gap is filled with a magnetic fluid. Further, reference numeral 13 denotes an elastic wire installed in a space formed between the yokes 128, 126 on both sides and the inner periphery of the magnet member 11, and is elastically deformed by being attached to the inner periphery of the magnet member 11. hand,
It is a ton that is rolled into multiple rolls and charged. This wire must be made of metal (for example) in order to obtain long-term reliability.

It is preferable to use phosphorized copper, stainless steel, etc., but a polymeric material (for example, Naipun, etc.) may be used as long as the material is less likely to deteriorate due to swelling or the like. Since a force that spreads outward acts on the wire rod 13 charged in this way, it presses the inner circumferential wall of the magnet member 11 and is firmly fixed at a position along the inner circumferential wall. The gap 1 formed between the inner circumference of the magnet member 11 and the wire rod
! 114, and gaps 15 formed between the wires when wound in multiple layers are filled with replenishing magnetic fluid.

FIG. 3 is a detailed cross-sectional view of the magnetic fluid seal of the present invention.The replenishing magnetic fluid 16 filled in the fixed gaps percolates into these gaps due to its surface tension and remains there. The number of winding layers of the wire rod does not limit the scope of the present invention, but if space is available, multi-layer winding is preferable because it allows filling of a large amount of replenishing magnetic fluid.

When the magnetic fluid 5 held in the gap between the movable rod 2 and the rings 12g and 126 evaporates into the outside air, the leakage magnetic flux in the gap increases, and the force of the magnetic lines of force causes the replenishing magnetic fluid 16 to evaporate into the outside air. is drawn into the void.

Since the replenishing magnetic fluid is automatically supplied to the seal portion in this way, complete sealing performance can be maintained for a long period of time even if the magnetic fluid evaporates.

As explained above, since the replenishment magnetic fluid holding member of the present invention is formed of an elastic wire, it is excellent in mass production, and can be easily produced by the spring force in the spreading direction of the elastic wire itself. Since it is firmly fixed to the inner circumferential wall of the magnet member, it has the advantage of being easy to assemble and not being deformed by external disturbances. Furthermore, the structure is simple and reliable, and therefore, there is an advantage that a highly reliable self-replenishing magnetic fluid seal can be easily manufactured.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a configuration diagram of a conventional example, FIG. 2 is a perspective sectional view showing a main part of an embodiment of the present invention, and FIG. 3 is a partially detailed view of FIG. 2. 1 is the housing, 2 is the movable rod, 3 is the permanent stone, 4g
, 4M, 12a, 126 are aluminum, 5, 16 are magnetic fluids, 6 is an impregnated material, 11 is a magnet member, 13 is a wire rod, 14.1
The town is a gap. Patent applicant Nippon Telegraph and Telephone Corporation

Claims (1)

[Claims] #1 has annular yokes facing each other in contact with both ends of a cylindrical magnet member, and a movable rod penetrates through the inner periphery of the facingly arranged cubic yoke through a minute gap, and the movable rod penetrates through the minute gap. A replenishment magnetic fluid holding member is disposed in a space sealed with a magnetic fluid and formed between the magnet member and the annular hole, and the magnetic fluid held by the replenishment magnetic fluid holding member is In a magnetic fluid seal configured to be supplied to a minute gap, the replenishing magnetic fluid holding member is made of elastic wire or material deformed along the inner circumferential wall of the magnet member, and is A magnetic fluid seal characterized in that a magnet member is fixed to an inner circumferential wall of a magnet member by a restoring force.