JPS62147177A - Magnetic fluid sealing method using multipolar magnet and device thereof - Google Patents

Abstract

PURPOSE:To prevent demagnetization in a magnet, by forming at least one one magnet multipole-magnetized at all-round saturation, in a tubular shaft direction of a pole piece. CONSTITUTION:A multipolar magnet 70 is a permanent magnet formed into round tubular form to a shaft rod 1 and magnetizing four poles of N, S and N, S in the axial direction, and a magnetic fluid 5 is held between the multipolar magnet 70 and the shaft rod 1. A line of magnetic force of the multipolar magnet 70 flows as shown in 81-83, and since the magnetic fluid 5 is held between the shaft rod 1 and a magnetic pole part where the multipolar magnet is magnetized, a seal between the shaft rod and the multipolar magnet can be done. Therefore, the whole magnetic flux holdable by a magnetic material is increased and, what is more, a drop in coercive force is also prevented from occurring.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention uses a permanent magnet that magnetizes an integrally formed tubular or rod-shaped material to be magnetized in the axial direction all around it, and rotates it. The present invention relates to a magnetic fluid sealing method and apparatus using a multipolar magnet that obtains sealing properties by adhering magnetic fluid to a shaft or sliding shaft.

[Prior Art] Conventionally, rotary and sliding parts in external recording devices of computers, high pressure or high vacuum areas in clean rooms, etc. have been equipped with high dust generation prevention performance instead of oil seals or mechanical seals. , magnetic fluid seals with excellent sealing performance, ease of maintenance, etc. are used.

The basic structure of a conventional magnetic fluid seal will be explained with reference to FIGS. 2 and 3. In addition, in Figures 2 and 3,
The bearing and the case of the non-magnetic part are omitted.

FIG. 2 shows an example using one dipole magnet. In the figure, l is a shaft rod, 2 is a bipolar permanent magnet, 3 and 4 are pole pieces, and 5
is a magnetic fluid, 6 is the direction of magnetic field lines, and 7 is a seal edge. In FIG. 2, the magnetic fluid 5 is held in the gap between the sealing edge 7 and the shaft l by the lines of magnetic force 6 of the permanent magnet 2, and acts as a sealing material.

FIG. 3 shows an example in which four dipole magnets are combined.

In the figure, 21-24 are four dipole magnets, 31-35
is placed through the pole piece. In this case, the magnetic lines of force 41 flow between the dipole magnets 21 to 24 and the shaft rod 1,
The magnetic fluid 5 is connected to the seal edge 7 and the shaft rod 1 as in FIG.
It is held in the gap between the parts and acts as a sealing material.

[Problems to be Solved by the Invention] Conventional magnetic fluid seals all use bipolar magnets, and have several drawbacks as described below. That is, in the device shown in FIG. 2, the lines of magnetic force are densely present in the portions near the N and S poles, and the lines of magnetic force are fewer in the seal portion away from the poles. Therefore, the sealing effect at the periphery tends to be insufficient, and to compensate for this, a stronger magnet is required. Furthermore, in this case, the magnetic fluid accumulates excessively in the seal near the pole, resulting in disadvantages such as increased frictional resistance of the shaft and reduced durability.

- On the other hand, in the device shown in Figure 3, the same poles of the magnets are placed close to the IF, and the pole pieces between these must form an edge near the axis, so the diamagnetic force is strong. As a result, the overall magnetic flux decreases, and the effect remains much lower than the magnet's original ability. Furthermore, since it promotes demagnetization of the magnet, there is also a problem in durability.

It is an object of the present invention to provide a new method and device that improves on the drawbacks of the prior art.

[Steps to solve the problem] The magnetic fluid sealing method, which is the first invention of this application, magnetizes an integrally formed tubular or rod-shaped magnetized material in the axial direction with a total of m multipolar magnets. The rotary shaft or the sliding shaft is sealed with a magnetic fluid and a pole piece portion having at least -• magnets.

A magnetic fluid sealing device, which is a second invention of this application, is an apparatus for carrying out the method of the first invention, and includes a pole piece having a fixed tubular permanent magnet, and a magnetic fluid sealing device sealed inside the pole piece. A magnetic fluid sealing device for sealing a rotating shaft or a WJ moving shaft with magnetic fluid, characterized in that at least one magnet with saturated multipolar magnetization is formed on the entire circumference in the axial direction of the tubular shape of the pole piece. That is.

A magnetic fluid seal device, which is the third invention of this application, is a device for carrying out the method of the first invention, in which a multipolar magnet is installed on a rotating shaft or a sliding shaft, and a pole piece is attached to a fixed part. It is characterized by being installed in

As described above, the feature of the present invention lies in the use of a multi-pole magnet in which a tubular or rod-shaped integrally formed magnetized material is saturation magnetized all around, in the magnet bronch part of the magnetic fluid seal. More specifically, the present invention relates to the use of a multipolar magnet in which the multipolar magnetization pattern is controlled to a desired and suitable shape and strength. Such a multipolar magnet can be manufactured by the method described in Japanese Patent Application Laid-Open No. 107809 and Japanese Patent Application No. 60-221952, which were previously filed by the present inventors.

In other words, the second aspect of the multipolar magnet used in the present invention is a circular tube-shaped magnetic material that surrounds a shaft that rotates or slides with a minute gap, and has a magnetic material that extends in the axial direction on the inner surface. It has a magnetically multi-stage ring structure in which there are a plurality of poles, and the same poles with equal magnetic flux density are separated in the direction perpendicular to the axis. Or, conversely, place a bipedal magnet on the axis,
It has a structure in which magnetic poles are arranged in a multi-stage annular shape.

[Sakukawa] The multipolar magnet used in the present invention has N and S magnetic poles that alternate in the axial direction, and unlike conventional bipolar magnets, magnetic poles of the same polarity are not adjacent to each other. This prevents the diamagnetic force that occurs when magnets with the same polarity are placed close together.
The 'BtC magnetism of the magnet can also be suppressed.

As mentioned above, the present invention is characterized by using a multipolar magnet that is saturated magnetized all around the magnet block of the magnetic fluid seal, and the number of poles, configuration, etc. are according to the embodiments shown below. It is not limited to.

[Example] An example of the present invention is shown in FIG. In FIG. 1, l is a shaft rod, which indicates a rotating shaft or a sliding shaft. Further, 70 is a multipolar magnet (pole piece). Multipolar magnet 7
0 is a permanent magnet having a cylindrical shape and magnetized with four poles N, S, N, and S in the axial direction with respect to the shaft l, and a magnetic fluid 5 is placed between this multipolar magnet and the shaft. is being held.

According to the above configuration, the lines of magnetic force of the multipolar magnet 70 range from 81 to 81 in the figure.
83, and the magnetic fluid 5 is held between the shaft l and the magnetized magnetic pole part (N or S) of the multipolar magnet, thereby sealing the gap between the shaft rod and the multipolar magnet f7J1. be able to.

Furthermore, when a multi-pole magnet that is saturated magnetized all around is used for a magnetic fluid seal, the magnetic flux density of each individual pole can be arbitrarily controlled during magnetization, and the desired magnetic strength (magnetic flux density) can be set for each pole. ) can be obtained by ′j.

FIG. 4 shows another embodiment of the invention. This embodiment is an example in which a multipolar magnet 71 is installed on an l1lI rod l, and a magnetic fluid 5 is sealed in a gap between it and a wall surface 8 surrounding the outer periphery. In FIG. 4, the shaft rod 1 itself can be magnetized to form a multipolar magnet.

Note that in the present invention, it is not essential to provide the edge portion 7 shown in FIGS. 2 and 3, but the present invention can also be achieved by providing such an edge portion Yes, it does not prevent its installation.

[Effects of the Invention] As explained above, according to the present invention, the total magnetic flux that the magnetic material can have is increased, the efficiency of its utilization is greatly improved, and the coercive force is reduced (demagnetization phenomenon). is also prevented. Further, the production of the magnet block (and pole piece) can be simplified, and a compact magnetic fluid seal device with a simple structure can be easily manufactured.

[Brief explanation of drawings]

FIG. 1 is a block diagram of a magnetic fluid seal device according to the present invention, FIGS. 2 and 3 are block diagrams of a conventional device, and FIG. 4 is a block diagram of another magnetic fluid seal device according to the present invention. ■... Axial rod, 5... Magnetic fluid, 70.71... Multipolar magnet.

Claims (1)

[Scope of Claims] 1) A rotating shaft is formed by a pole piece portion having at least one magnet in which an integrally molded tubular or rod-shaped magnetized material is saturated and multipole magnetized all around in the axial direction, and a magnetic fluid. Or a magnetic fluid sealing method using a multipolar magnet characterized by sealing a sliding shaft. 2) A magnetic fluid sealing device that seals a rotating shaft or a sliding shaft with a pole piece having a fixed tubular permanent magnet and a magnetic fluid sealed inside the pole piece,
A magnetic fluid sealing device using a multipolar magnet, characterized in that at least one magnet that is saturated multipolar magnetized all around the pole piece is formed in the axial direction of the tubular shape of the pole piece. 3) A magnetic fluid seal device using a multipolar magnet, characterized in that a multipolar magnet is installed on a rotating shaft or a sliding shaft, and a pole piece is installed on a fixed part.