JPH0361072B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a method for maintaining a pressure difference between a first region and a second region or for preventing a flow of liquid or gas between the first region and the second region in a device having a rotating shaft. The present invention relates to a sealing device.

A conventional sealing device of this kind, for example, as shown in FIG. The structure is such that a magnetic fluid 6 is interposed in the gap between the rotating shaft 1 and the yokes 3 and 4, which are fixed together.

According to such a configuration, the rotating shaft 1 and the yoke 3,
If the concentricity with 4 is not achieved, the sealing pressure when the rotating shaft 1 rotates will decrease. In addition, in order to improve the sealing effect, the spacing between the magnetic shaft 1 and the yoke is set small, so that when assembling this device, that is, when inserting the rotating shaft 1 into the magnetic circuit, the magnetic fluid cannot be injected later. is often difficult. Therefore, as a result of inserting the rotating shaft 1 after applying the magnetic fluid into the magnetic circuit, the magnetic fluid ends up adhering to the rotating shaft 1. Therefore, it is often difficult to determine whether the amount of magnetic fluid present in the gap is appropriate until the device is actually operated, resulting in a decrease in reliability. In order to further improve the degree of sealing, it is possible to consider an apparatus that forms a plurality of voids, but this has the drawback of increasing the number of processing steps required to form the voids.

Therefore, a yoke facing both poles of a permanent magnet is installed with a small gap between it and a part of the moving body (or rotating body), and a porous body is provided between the opposing surfaces of the yoke. Devices impregnated with magnetic fluid are known (for example, Japanese Patent Application Laid-Open No. 55-30562).
However, since the permanent magnet is not in direct contact with the rotating body, etc., but via a yoke, the magnetic fluid between the yoke and the rotating body, etc. is retained by relying on the leakage magnetic flux of the permanent magnet. Therefore, in order to strengthen the retention of the magnetic fluid between the yoke and the rotating body, it is necessary to increase the magnetic force and size of the permanent magnet. but,
Depending on the mode of use, there are places where the permanent magnets are limited, and it is difficult to easily change the permanent magnets at such places.

In view of this, the present invention arranges a permanent magnet so as to be in direct contact with the thrust surface of a rotating body, etc., and improves the ability to retain the magnetic fluid interposed between the rotating body and the like without changing the permanent magnet. The main purpose is to propose a sealing device of this type that is designed to maximize the performance.

An embodiment of the present invention will be described in detail below with reference to the drawings.

FIG. 2 is a longitudinal sectional view showing an example of the present invention.
8 is a rotating shaft, and 10 is a housing. Rotating shaft 8
A disc-shaped protrusion 9 is formed integrally or separately. When forming the protruding portion 9 as a separate body, the protruding portion 9 is
Make sure to fix it to A side surface (thrust surface) of the protruding portion 9 is made to correspond to a side surface (thrust surface) of the housing 10. A ring-shaped permanent magnet 11 is fixed to the surface of the non-magnetic housing 10, and a predetermined gap C is formed between the permanent magnet 11 and the protrusion 9. In this case, the magnetic pole surface of the permanent magnet 11 is magnetized in an annular shape. The number of magnetizations can be one or more. A magnetic fluid is interposed in the gap C between the convex portion 9 and the permanent magnet 11.

When incorporating the rotating shaft 8 into the housing 10,
When a predetermined amount of magnetic fluid is applied to the magnetized surface of the permanent magnet 11, the magnetic fluid 12 adheres in a circular or concentric form, so that when the rotating shaft 8 is inserted thereafter, the magnetic fluid will not adhere to the rotating shaft 8. .

FIG. 3 is a longitudinal sectional view showing another example of the present invention. In this example, a yoke 14 made of a soft magnetic material is provided on the opposite side of the magnetic pole of the permanent magnet 11, and the housing 10 is
It is fixed at . Permanent magnets are effective when using magnets that are anisotropic in the thickness direction. By providing the yoke 14, the magnetic field strength in the gap C can be increased. In this case, by setting a plurality of permanent magnets 11 to be magnetized, and by setting a plurality of magnetizations to the magnetic fluid 12, the sealing effect of the magnetic fluid 12 can be further enhanced.

FIG. 4 is a longitudinal sectional view showing still another example of the present invention. In this example, a yoke 14 fixed to a permanent magnet 11 is used.
is formed to have an L-shaped cross section. In other words, it is formed into a cylindrical shape extending from the outer periphery of the yoke, which is a soft magnetic pole piece.
A surface that is the same as the thrust surface of the permanent magnet 11 is formed. Therefore, a magnetic circuit of the protruding portion 9, the permanent magnet 11 and the yoke 14 is formed,
The magnetic fluids 12 and 17 are present in the gap between the protrusion 9 and the permanent magnet 11 and in the gap C between the protrusion 9 and the yoke 14. A reserve amount of the magnetic fluids 12, 17 can be stored in an annular recess 13 formed between the permanent magnet 11 and the yoke 14.

FIG. 5 is a longitudinal sectional view showing still another example of the present invention. In this example, a permanent magnet 11 and a yoke 14 are installed between a fixed central shaft 21 and a rotating housing 22 in the same manner as described above.
For example, this is a suitable example for application to an outer rotor motor. Of course, there are rotating housings 22 other than those shown.
The permanent magnet 11 and the yoke 14 can be fixed to the structure.

FIG. 6 is a sectional view showing still another example. 23
is a concentric annular groove 2 on the surface corresponding to the convex portion 9 side.
3a indicates a permanent magnet formed of one or more. A magnetic pole is formed on each convex surface 23b formed between the annular grooves 23a. Similar to the example in FIG. 5, the magnetic fluid 12 can be stored in the annular groove 23a. Of course, yokes can also intervene.

As explained above, according to the present invention, a permanent magnet fixed to the rotating body or the non-rotating body is provided between the thrust surface of the rotating body and the thrust surface of the non-rotating body, and the permanent magnet It has a magnetic pole face that directly faces the surface, and a magnetic fluid is interposed in the gap between the rotating body or non-rotating body and the permanent magnet, so the permanent magnet does not face the rotating body through the yoke as in the conventional case. The holding ability of the magnetic fluid is much greater than that of a configuration in which the permanent magnet has the same ability as that of a permanent magnet, and even if the magnet itself is set small, the holding ability of the magnetic fluid can be sufficiently exhibited. Therefore, even if there is a disturbance object that disturbs the closed magnetic path that holds the magnetic fluid in the vicinity of the sealing device, the disadvantage that the magnetic flux of the closed magnetic path changes and the magnetic fluid leaks can be overcome. Furthermore, since the degree of sealing can be maintained without minimizing the difference in diameter between the rotating body and the permanent magnet, there is no need to make the inner diameter of the hole for penetrating the shaft of the permanent magnet unnecessarily strict. It is possible to reduce the number of processing steps.

In addition, to increase the degree of sealing, it is necessary to use multiple stages, but the magnetization of the permanent magnet can now be done using a plane magnetization method, and this can be easily solved by using an anisotropic magnet that is magnetized in the thickness direction. obtain.

Furthermore, when trying to fit the rotating body and the non-rotating body,
There is no loss of magnetic fluid, and therefore the degree of sealing can be faithfully expressed by calculating the amount of inserted magnetic fluid, making it possible to obtain this type of highly reliable sealing device. Further, since adhesion of magnetic fluid does not occur, the fitting operation can be facilitated.

[Brief explanation of drawings]

FIG. 1 is a diagram for explaining the conventional technology, FIG. 2 is a cross-sectional view showing one example of the present invention, and FIGS. 3, 4, 5, and 6 are cross-sectional views showing other examples of the present invention, respectively. It is a diagram. 8...Rotating shaft, 9...Protrusion, 10...Housing, 11...Permanent magnet, 12...Magnetic fluid, 1
4... Yoke, 21... Fixed shaft, 22... Rotating housing.

Claims (1)

[Claims] 1. A permanent magnet fixed to the rotating body or the non-rotating body is provided between the thrust surface of the rotating body and the thrust surface of the non-rotating body, and the permanent magnet is directly opposed to the thrust surface. 1. A thrust bearing sealing device, characterized in that the thrust bearing sealing device has a magnetic pole surface that is symmetrical, and a magnetic fluid is interposed in a gap between the rotating body or the non-rotating body and the permanent magnet. 2. The thrust bearing sealing device according to claim 1, wherein the magnetic pole faces of the permanent magnet are formed in a plurality of annular shapes. 3. The thrust according to claim 1 or 2, wherein a soft magnetic pole piece is provided between the rotating body or non-rotating body and the permanent magnet fixed to the rotating body or non-rotating body. Bearing sealing device. 4. The soft magnetic pole piece is extended to be flush with the permanent magnet, and the magnetic fluid is also interposed in the gap between the soft magnetic pole piece and the rotating or non-rotating body. The thrust bearing sealing device according to item 3.