JPH03222150A - Magnetic disk driver - Google Patents

Abstract

PURPOSE:To shut off a foreign matter which falls naturally from outside and sticks on a magnetic fluid seal by providing an annular dust protective cover which is fixed to the hub of a magnetic disk at its one end, and holds a small clearance between the other end and a fixed shaft. CONSTITUTION:Two sheets of disk-shaped magnetic fluid seal plates 13 are fixed to the hub 2 as interposing a magnet 16 between. The magnetic fluid 14 is held in the magnetic loop-shaped clearance arranged between the seal plate 13 and the fixed shaft 10 by its magnetism, and a bearing member 15 is isolated perfectly from the side of the storage space of a disk 1. In this constitution, the outer circumference of the dust protective cover 12 holding the clearance in a height direction enough to keep itself not brought into contact with the magnetic fluid 14 is fixed to the hub 2. This cover 12 is annular, and its inner circumference holds the minimum clearance (a) to the fixed shaft 10. Thus, the falling and the sticking of the foreign matter from an upper part can be almost prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a magnetic disk drive device that rotatably supports a magnetic disk.

2. Description of the Related Art Conventionally, in a magnetic disk drive device that rotatably holds a magnetic disk, a button is used to separate dust generated from a bearing member that rotatably holds the magnetic disk from a storage space for the magnetic disk. A magnetic fluid seal is arranged between the storage space and the bearing member.

The magnetic fluid seal includes an annular magnetic fluid seal plate and a magnetic fluid held by a magnetic loop between a rotating part and a non-rotating part.

Problems to be Solved by the Invention However, if foreign matter gets mixed into the magnetic fluid seal during the assembly process, it may be scattered toward the outer periphery due to centrifugal force, or if it is thread-like, it may be dispersed by capillary action. there were.

These foreign substances are not dust that is generally generated from bearing members, but most of them are foreign substances that enter from the outside during the assembly process after injecting the magnetic fluid or during handling such as break-in operation.

The present invention aims to solve the above problems.

Means for Solving the Problems The magnetic disk drive device of the present invention has a hub that fixedly holds a magnetic disk and is rotatably held on a fixed shaft by a bearing member, and a space that accommodates the bearing member and the magnetic disk. an annular magnetic fluid sealing plate that rotates together with the hub and forms a magnetic fluid seal with the fixed shaft, and is located between the magnetic fluid sheet tvW material and the magnetic disk storage space; The present invention is characterized by comprising an annular dustproof cover, one end of which maintains an extremely small gap with the fixed shaft, and the other end of which is fixed to the knob.

Effect According to the above configuration, the magnetic fluid seal is isolated from the outside world by the extremely small gap formed between the magnetic fluid seal and the fixed shaft by attaching the dustproof cover after the magnetic fluid is injected, and is naturally isolated from the outside world. All the foreign matter that falls and adheres to this dust cover! ll will be blocked.

In particular, foreign matter carried by air convection generated by the rotation of the knob during break-in operation can be completely blocked by the labyrinth seal effect that occurs in the tiny gap between the dustproof cover and the fixed shaft.

Example An embodiment of the present invention will be described based on the drawings.

FIG. 1 is a sectional view of a magnetic disk drive device according to the present invention;
FIG. 2 is an enlarged sectional view of the vicinity of the magnetic fluid seal of the device.

In the drawing, two magnetic disks 1a and 1b are fixed to a disc press 2 by a disk holding plate 4 with an annular disk spacer 3 in between.

! In addition, the knob 2 is fixed to the outer ring 9 of a bearing member 15 which is rotatably held via two upper and lower ball rows 11 around a fixed shaft 10 fixed to the base 6, and rotates in the vertical direction. It is maintained so that it can rotate smoothly without any play.

An annular main magnet 7 is fixed to the inner circumferential side of the encased knob 2 via an annular knob yoke 6.
By energizing the armature 8 fixed to the pace 5 opposite to it, it becomes a motor.

The housing hub 2 has an outer ring 9. as shown in detail in FIG. Two disk-shaped magnetic fluid sealing plates 13 are adhesively fixed to the outside of the bearing member 15 constituted by the fixed shaft 10 and the ball row 11 (on the storage space side of the magnetic disk 1), with the magnet 16 sandwiched therebetween. The magnetic fluid 14 is magnetically held in the gap on the magnetic loop provided between the magnetic fluid sealing plate 13 and the fixed shaft 1o, and the magnetic fluid 14 is held in the gap on the magnetic loop provided between the magnetic fluid sealing plate 13 and the fixed shaft 1o. The side and the magnetic disk storage space side are completely isolated.

Further, on the side of the magnetic disk storage space formed by the magnetic fluid seal, a dustproof cover 12 is adhesively fixed to the 7.gage 2 with a gap in the height direction sufficient to prevent contact with the magnetic fluid.

This dustproof cover 12 has an annular shape, is adhesively fixed to the nozzle 2 on the outer peripheral end surface side, and has a fixed shaft 1o on the inner periphery.
In contrast, an extremely small gap a is maintained.

This gap a has a dimension of 1/3 or less of the plate thickness of the dustproof cover 12 and a dimension of 0.1 m/m or less, so it prevents foreign matter from falling and adhering to the magnetic fluid. All can be prevented.

Conventionally, this dustproof cover 12 was not attached, so foreign objects could be freely removed from the top (magnetic disk storage space side) of the magnetic fluid 14.
Most manufacturers carry out a break-in operation (aging) for several hours to stabilize the characteristics of the motor after it is mixed into the casing and assembled. 2 or the rotation of the magnetic disk 1, air convection occurs in the direction of the arrow.

That is, hub 2. Air near the contact surface of the magnetic disk 1 flows toward the outer periphery due to centrifugal force, circulates, and comes around near the center of the fixed shaft. At this time, if foreign matter is floating in the air, it adheres to the magnetic fluid.

In the dustproof cover 12 of this embodiment, the gap a generates a labyrinth seal effect to prevent foreign matter from entering due to air convection during such operation.

Effects of the Invention As described above, according to the present invention, it is possible to almost prevent the attachment of foreign matter due to natural fall of the button during operation after injecting the magnetic fluid.
The adhesion of foreign matter carried by air convection generated during disk rotation during break-in operation etc. can be completely prevented by the Rabinne seal effect created by the extremely small gap d between the dustproof cover and the shaft.

Due to the above two points, it is possible to prevent the scattering and diffusion of the magnetic fluid due to the contamination of foreign matter, and it is possible to eliminate problems with the magnetic disk and the head caused by this.

[Brief explanation of drawings]

FIG. 1 is a sectional view of a magnetic decoupling drive device according to an embodiment of the present invention, and FIG. 2 is an enlarged sectional view of a main part of the same embodiment. 1...Magnetic disk, 2...Hub, 10...
・Fixed shaft, 12...Dust-proof cover, 13...
・Magnetic fluid sill plate, 14...Magnetic fluid, 15...
・Bearing parts.

Claims (1)

[Claims] A hub fixedly holds the magnetic disk and is rotatably held on the fixed shaft by a bearing member, and is arranged between the bearing member and a space for storing the magnetic disk, rotates together with the hub, and is connected to the fixed shaft. an annular magnetic fluid sealing plate that forms a magnetic fluid seal therebetween; the magnetic fluid sealing plate is disposed between the magnetic fluid sealing plate and the magnetic disk storage space, and one end maintains an extremely small gap with the fixed shaft; What is claimed is: 1. A magnetic disk drive device comprising: a ring-shaped dustproof cover whose other end is fixed to the hub;