JPS60172777A - Seal device for rotary shaft, utilizing magnetic fluid - Google Patents

Abstract

PURPOSE:To prevent a magnetic fluid in a magnetic seal device from scattering, by communicating a space defined between a bearing and the magnetic fluid with the external space to obtain a pressure balance. CONSTITUTION:An annular permanent magnet 2 magnetizes the outer peripheral surface of a rotary shaft 1 supported to a housing 9 by means of bearings 7, 8, and magnetic fluids 5, 6 are constrained between the inner surfaces of magnetic pole pieces 3, 4 and the outer peripheral surface of the rotary shaft 1 under the magnetic force of the permanent magnet 2. Further, a pressure hole 10 formed in the housing 9 is opened at one end to the exterior and the other end to a space between the magnetic pole piece 3 and the bearing 8. Accordingly, the pressure in the magnetic seal area or the pressure in the space between the magnetic seal area and the mechanical support area may be prevented from varying in association with temperature variations, thereby it is possible to prevent the magnetic fluid from scattering.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a rotary shaft sealing device using magnetic fluid.

Conventionally, a rotating shaft to which this type of seal device is applied has been mechanically supported by a bearing. In order to prevent the bearing from being contaminated by the external environment, the outer periphery is fixed to the inner periphery of the outer race and the inner periphery is slightly spaced apart from the outer periphery of the inner race with a dustproof cover made of rubber or the like, or the inner periphery is covered with an inner periphery. It included a dustproof cover made of rubber or the like which was fixed to the outer periphery of the race and whose outer periphery was slightly spaced from the inner periphery of the outer race. However, in this case, after installing the outer race on the nozzle and the inner race on the rotating shaft, when assembling each other, the outer race and the inner race tend to be misaligned, and as a result, the free edge of the dustproof cover and the inner race tend to be misaligned. Alternatively, there was a problem in that the space between the bearing and the outer race was blocked by the grease placed inside the bearing.

If the free edge of the dustproof cover of the bearing is blocked in this way, when the pressure near the sealing device increases due to a rise in temperature, the magnetic fluid will be pushed outward from the restricted area, and as the rotating shaft rotates. It had the disadvantage that it was often scattered.

The object of the present invention is to provide a sealing device that eliminates the above-mentioned drawbacks and prevents magnetic fluid from being scattered.

Hereinafter, the sealing device of the present invention will be explained with reference to the drawings.

In the figure, (1) is a rotating shaft made of magnetic material, one end of which is normally connected to a rotational drive source, and the other end connected to a rotating body such as a computer disk placed in a clean room. (2) is an annular permanent magnet placed around the rotating shaft (11) apart from the surface of the rotating shaft (1), and is magnetized in the axial direction of the rotating shaft (1). Reference numerals 31 (4) denote annular magnetic pole pieces, each of which is in contact with both end faces Ka of the permanent magnet, and whose inner circumferential surface faces the circumferential surface of the rotating shaft (1) with a slight interval. (5M6) are magnetic fluids, which are restrained by the magnetic force of the permanent magnet (2) between the inner circumferential surface of the magnetic pole piece (3) (/l) and the circumferential surface of the rotating shaft (1). (7) and (8) are earrings that support the rotating shaft (1) on a non-magnetic housing (9)., (7AX7B) are made of Zam plastic or other appropriate material. The outer circumference of the dustproof cup 9- is fixed to the inner circumference of the outer race of the bearing (7), and the inner circumference is slightly spaced apart from the outer circumference of the inner race of the bearing (7).

(8A) and (8B) are other dustproof covers made of rubber, plastic, or other appropriate materials, the outer periphery of which is fixed to the inner periphery of the outer race of the bearing (8), and the inner periphery of which is fixed to the inner periphery of the outer race of the bearing (8). It is slightly spaced apart from the outer periphery of the inner race of the bearing (8). 00) is a pressure hole drilled in the No. 1 song (9), one end of which is open to the outside, and the other end of which is open to the space between the magnetic pole piece (3) and the bearing (8). ing.

In the sealing device of the present invention, when assembling the rotating shaft (1) into the housing (9), the bearing (force)
Misalignment occurs between the outer race and the inner race of 8), and as a result, the dust cover (7A), (713), (8A), (
8] Even if the air gap between any of the inner peripheral edges of item 1) and the inner race is blocked by grease, the space between the bearing (8) and the magnetic pole piece (3), that is, the rotating shaft (1), is closed by the pressure hole. ), the space between the mechanical support area and the magnetic seal area is communicated with the external space, so the pressure in the magnetic seal area or the pressure in the space between the magnetic seal area and the mechanical support area is affected by changes in temperature, etc. It is possible to avoid fluctuations caused by the magnetic fluid in the magnetic seal area (5
) (6) is not pressed in a direction that deviates from the restraint area. Therefore, according to the sealing device of the present invention, the magnetic fluid is not scattered, the sealed clean room is not contaminated, and the service life can be extended.

In the seal device of the present invention, there is no limit to the configuration of the magnetic seal area, and it is clear that a design change such as magnetizing the permanent magnet in the radial direction of the rotating shaft may be adopted. It will also be clear that even if the nozzle is made of a magnetic material, there is no problem with the sealing device of the present invention since the magnetic seal area or the rotating shaft can be modified appropriately.

In addition, in the sealing device of the present invention, 1. It is also clear that there are no particular limitations on the shape and configuration of the dustproof cover of the bearing f7) (8).

Furthermore, in the sealing device of the present invention, it is sufficient to connect the space between the mechanical support area of the rotating shaft and the magnetic seal area to the outside space to maintain pressure balance. It is clear that other communication configurations other than the hole aυ may also be used. It will also be clear that for example at least one pressure tube may be arranged between the bearing <7) (8) and the housing (9) to achieve said pressure balance. It is also clear that a plurality of pressure holes aυ may be provided.

Note that the sealing device of the present invention can also be used when a bearing without a dustproof cover is used.

That is, even if a bearing does not have a dustproof cover, the space between the inner race and the outer race may be blocked by grease or the like, making it impossible to maintain the pressure balance at both ends of the bearing.In order to eliminate this drawback, the present invention has been developed. It will be clear that other sealing devices may also be used.

[Brief explanation of the drawing]

The figure shows an embodiment of the sealing device of the invention. 1...Rotating shaft, 2...Permanent magnet, 3.4...
・Magnetic pole piece, 5, 6...Magnetic fluid, 7.8...Bearing, 7A, 7B, 8A, 8B...Dust-proof cover, 9
...Housing, 10...Pressure hole.

Claims (5)

[Claims] (1) A sealing device in which a rotating shaft mechanically supported by a bearing relative to a housing is sealed by a magnetic fluid restrained by the magnetic force of a permanent magnet at a penetrating portion of the housing, the bearing and the magnetic fluid. A sealing device characterized in that the space between the two is communicated with an external space to maintain pressure balance. (2) The sealing device according to claim 1, wherein the space between the bearing and the magnetic fluid is communicated with the external space through at least one pressure hole bored in the housing song. . (3) The space between the bearing and the magnetic fluid is communicated with an external space through at least one pressure pipe disposed between the bearing and the housing. The sealing device according to item 1. (4) The outer peripheral edge of the dustproof cover is fixed to the outer race of the bearing, and the inner peripheral edge is extended to the vicinity of the inner race, as described in any one of claims 1 to 3. sealing device. (5) The inner peripheral edge of the dustproof cover is fixed to the inner race of the bearing, and the outer peripheral edge is extended to the vicinity of the outer race, as described in any one of claims 1 to 3. sealing device.