JPH0434277Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a magnetic fluid seal used as a sealing means between a shaft and a housing supporting the shaft.

(Prior Art) A magnetic fluid seal as illustrated in FIG. 6 is widely used as a sealing means for a gap formed between a shaft and a housing supporting the shaft.

The magnetic fluid seal in the figure is, as shown in figure a,
The housing 2 has N and S poles arranged in the axial direction.
The structure is shown in Fig. b, in which magnetic pole pieces 3 made of a magnetic metal material and made into a substantially snake-eye shape are attached to both sides of the magnet 1 attached to the magnet 1 to form a minute gap with the circumferential surface of the shaft 4. As shown in FIG.
A magnetic pole piece 3 made of a magnetic metal material in the shape of a perforated dish is attached to form a small gap with the circumferential surface of the shaft 4, and a gap between the inner end and the magnet 1. The magnetic fluid 5 injected into the gap formed between the circumference of the magnetic pole piece 3 and the shaft 4
- The magnetic circuit formed through the pole piece 3 and the shaft 4 is retained to maintain the sealing function between the housing 2 and the shaft 4.

(Problems to be Solved by the Invention) In the magnetic fluid seal described above, since it is necessary to hold the magnetic fluid 5 that provides the sealing function in a minute gap between the circumferential surfaces of the magnetic pole piece 3 and the shaft 4,
In addition to setting the distance as narrow as possible, the concentricity between the housing 2 and the shaft 4 and the housing 2
Since it is necessary to accurately maintain the concentricity between the magnetic pole piece 3 and the magnetic pole piece 3, it is necessary not only to set the accuracy of the engagement of the magnetic pole piece 3 to the housing 2 and the holding accuracy of the shaft 3 by the housing 2 to be high, but also to maintain the concentricity between the magnet 1 and the magnetic pole piece 3. 3
When assembling the shaft 4 into the housing 2, or attaching the shaft 4 to the magnetic pole piece 3.
This requires extreme care when inserting into the machine, leading to increased processing costs and damage to component parts.

Furthermore, since the magnet 1 and the magnetic pole piece 3 are both made of metal materials, the fitting system must be adjusted in order to maintain the sealing function when the two members 1 and 3 are fitted with the housing 2. needed to be set high.

The purpose of the present invention is to provide a structure of a magnetic fluid seal that does not require high precision in the concentricity between the housing and the shaft or the concentricity between the housing and the magnetic pole piece, and can maintain a strong sealing function. It is something to do.

(Means for Solving the Problems) In consideration of the problems in the magnetic fluid seals according to the conventional technology described above, the present invention has developed a magnet that is attached to a magnet attached to a housing and is placed between the circumferential surface of the shaft and the The magnetic pole piece, which forms a gap and into which a magnetic fluid is injected, is made of a magnetically permeable elastomer or a magnetically permeable plastomer in which magnetic powder is dispersed in an elastomer and a plastomer. It is what you do.

If the fluid to be sealed has positive or negative pressure and pressure acts on the magnetic pole piece, a magnetically permeable metal plate is used inside or on the side of the magnetic pole piece made of magnetically permeable elastomer or magnetically permeable plastomer. A reinforcing member is added.

Furthermore, a magnetic pole piece made of a magnetically permeable plastomer or a magnetically permeable elastomer is formed into an annular body having a substantially U-shaped cross-sectional shape or a substantially L-shaped cross-sectional shape, so that the outer circumferential side of the magnet is covered by the cylindrical portion of the magnetic pole piece. It is also possible to have a structure.

(Function) The magnetic fluid seal according to the present invention having the above-mentioned configuration is made of magnetically permeable elastomer or magnetically permeable plastomer, and is attached to a magnet to hold the magnetic fluid between it and the circumferential surface of the shaft. The magnetic pole pieces elastically contact the outer circumference with the inner circumference of the housing to ensure the sealing of the mating part with the housing, and when eccentricity occurs between the housing and the shaft, the elasticity of the inner circumference It shows the function of absorbing eccentricity between the housing and shaft due to deformation and protecting the shaft circumferential surface from damage.

(Embodiment) In the embodiment shown in FIG. 1a, magnetic powder is dispersed in an elastomer or plastomer on both sides of a magnet 1 mounted on a housing 2 with N and S poles arranged in the axial direction. A magnetic pole piece 3 made of a magnetically permeable elastomer or magnetically permeable plastomer and having a substantially snake-eye shape is attached, and the magnetic pole piece 3 and the shaft 4 are attached to each other.
The magnetic fluid 5
is injected.

In the embodiment of FIG. 1b, a magnetic pole piece made of magnetically permeable elastomer or magnetically permeable plastomer in the shape of a perforated dish is attached to the side surface of the magnet 1 in which the north and south poles are arranged in the radial direction. 3 is attached, and a magnetic fluid 5 is held in a minute gap formed between the magnetic pole piece 3 and the circumferential surface of the shaft 4.

In the embodiments shown in FIGS. 2a and 2b, in order to strengthen the pressure resistance of the pole piece 3 made of a magnetically permeable elastomer or a magnetically permeable plastomer, the pole piece 3 is made of a magnetically permeable metal plate material. A reinforced reinforcing member 6 is embedded inside the magnetic pole piece 3.

In the embodiment shown in FIG. 3a, the magnetic pole piece 3 is made into an annular body having a substantially U-shaped cross section and covers the outer peripheral surface and both side surfaces of the magnet 1, and in the embodiment shown in FIG. In this case, the magnetic pole piece 3 is made into an annular body having a substantially L-shaped cross section, and covers the outer circumferential surface of the magnet 1 and the outer portion of one side surface.

In the embodiment of FIGS. 4a and 4b, the outer peripheral surface of the magnet 1 and the pole piece 3 made of a magnetically permeable elastomer or a magnetically permeable plastomer is attached to a cylindrical member made of a non-magnetic elastomer. Twisted and covered.

In the embodiment of FIGS. 5a and 5b, inside the magnet 1 and the pole piece 3 made of a magnetically permeable elastomer or a magnetically permeable plastomer, a reinforcement made of a magnetically permeable plate material is provided. A member 6 is embedded.

In the embodiments shown in FIGS. 2 and 5, the reinforcing member 6 is embedded inside the magnetic pole piece 3; It is also possible to attach it to one side or both sides of the piece 3.

(Effects of the invention) As described above, the magnetic fluid seal of the invention has
A magnetic pole piece that is attached to a magnet attached to the housing and forms a minute gap with the circumferential surface of the shaft, and holds the magnetic fluid injected into the minute gap, transfers the magnetic powder into the elastomer or plastomer. Since the magnetically permeable elastomer or magnetically permeable plastomer is dispersed in the housing, the elastic contact of the outer circumferential part of the magnetic pole piece with the inner circumferential surface of the housing allows the contact between the magnet and the magnetic pole piece and the housing. Not only is the sealing function of the joint firmly maintained, but when eccentricity occurs between the housing and the shaft, the inner circumference of the magnetic pole piece elastically deforms to absorb the eccentricity between the housing and the shaft. Since damage to the circumferential surface of the shaft is protected, the machining precision required in conventional magnetic fluid seals is not required, and moreover, normal sealing function is maintained over a long period of time.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of one embodiment of the present invention, FIGS. 2 to 5 are sectional views of other embodiments of the present invention, and FIG. 6 is a sectional view of a magnetic fluid seal according to the prior art. It is a sectional view of an example. DESCRIPTION OF SYMBOLS 1... Magnet, 2... Housing, 3... Magnetic pole piece, 4... Shaft, 5... Magnetic fluid, 6... Reinforcement member.

Claims (1)

[Scope of utility model registration request] A magnet 1 attached to a housing 2 and a magnetically permeable elastomer or a magnetically permeable plastomer made by dispersing magnetic powder in an elastomer or plastomer are made into a substantially snake-eye shape, and attached to the magnet 1 is a shaft 4. A magnetic fluid seal comprising a magnetic pole piece 3 forming a minute space between the circumferential surface of the magnetic pole piece 3 and a magnetic fluid 5 injected between the magnetic pole piece 3 and the circumferential surface of the shaft 4.