JP2892143B2 - Magnetic disk drive - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a magnetic disk drive that drives a magnetic disk to rotate.

(Conventional technology and its disadvantages)

In general, a conventional magnetic disk drive is configured as shown in FIG. That is, a magnetic disk (hereinafter, referred to as a magnetic disk)
The hub member 8 on which the disk 32 is mounted is the shaft member 1
It is rotatably supported via bearing members 3 and 4 fitted to the outside.

A rotor magnet 6 is provided inside the hub member 8, and the disk 32 is driven to rotate by relative rotation with respect to the stator 5 externally fitted to the bearing member 1. A predetermined number of disks 32, for example, four disks 32 are mounted on the hub member 8, and the spaces between the disks are held at predetermined intervals by the spacers 31. Then, the disc 32 is integrally fixed to the hub member 8 by screwing the clamp member 33 to the hub member 8 with the mounting screw 30.

Normally, the hub member 8 is made of an aluminum material which is easy to work out and which is easy to process.

Incidentally, in order to prevent the lubricating oil contained in the bearing members 3 and 4 and the unclean air retained inside the hub member 8 from flowing out into the disk chamber 10 and contaminating the same, as a sealing means, for example, a magnetic fluid seal is used. Mechanisms 9, 9 are provided.
This is composed of a magnetic fluid unit 94 filled and held in a gap between a magnetic circuit unit in which a donut-shaped magnet 92 is sandwiched between ferromagnetic pole pieces 91 and 93 and a shaft member 1,
The inside of the hub member 8 and the inside of the disk chamber 10 are partitioned by the magnetic fluid layer generated by the magnetic fluid 94. Reference numeral 90 denotes a protective cap for preventing the magnetic fluid from flowing out into the disk chamber 10 in the event of scattering.

However, among the magnetic fluid sealing mechanisms 9, 9, especially on the upper side, that is, on the mounting side of the clamp member 33, the magnetic flux B leaked from the magnetic circuit unit of the magnetic fluid sealing mechanism 9 passes through the hub member 8, and the magnetic flux B passes through the disk. It leaks to the 32 side, and as a result, causes a read / write failure of a magnetic head (not shown). In particular, in recent years, in addition to the miniaturization of the device and the tendency for the magnetic head to have a higher sensitivity with a higher capacity, the problem is unavoidable.

[Object of the invention]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and a main object of the present invention is to provide a highly reliable magnetic disk which suppresses magnetic flux leakage from a magnetic fluid seal mechanism and does not cause a read / write failure of a magnetic head. It is to provide a driving device.

[Summary of the Invention]

According to the present invention, a magnetic disk, a spindle motor for driving the magnetic disk to rotate in a predetermined direction, and a clamp member for attaching the magnetic disk to the spindle motor are provided. A hub member rotatably supported via the magnetic disk and mounted on the hub member, a rotor magnet mounted on the hub member, a stator disposed opposite to the rotor magnet, and grease from the bearing means And a magnetic fluid seal mechanism for preventing scattering of the magnetic fluid, wherein an annular magnetic shield means constituted by a part of the clamp member is provided radially outside the magnetic fluid seal mechanism. A magnetic disk drive is provided.

In the magnetic disk drive described above, the following magnetic circuit is formed separately from the magnetic circuit that functions as the original seal mechanism of the magnetic fluid seal mechanism. From the magnetic fluid seal mechanism to the hub member (transmitted by nonmagnetic) to the magnetic shield means (converged by ferromagnetic) to the hub member (transmitted by nonmagnetic) to the magnetic fluid seal mechanism. As a result, most of the leakage magnetic flux that spreads outward in the radial direction of the hub member from the magnetic fluid sealing mechanism is converged on this magnetic circuit. Accordingly, the magnetic flux does not substantially leak further outward in the radial direction than the magnetic shield means, and the magnetic field does not reach the area of the disk. That is, the magnetic head accessing the disk is not substantially affected by the magnetic field, so that normal operation can be maintained without causing a read / write failure.

〔Concrete example〕

Hereinafter, specific examples of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 shows a first embodiment of a magnetic disk drive according to the present invention.
FIG. 1 is a cross-sectional view of a magnetic disk drive in which four 3.5-inch magnetic disks are mounted, for example. In FIG. 1, the same members as those already shown in FIG. 3 are denoted by the same reference numerals. In FIG. 1, 1 is a shaft member, 2 is a bracket, 3 and 4 are bearing members (constituting bearing means), 5 is a stator, 6 is a rotor magnet, 7 is an auxiliary yoke, 8 is a hub member, and 9 is magnetic. Fluid seal mechanism, 30
Is a mounting screw, 31 is a spacer, 32 is a disk, 34 is a clamp member, 41 is a bush, and 51 is a lead wire.

The shaft member 1 is made of a ferromagnetic material such as carbon steel, for example, and has one end fixed to the bracket 2. Bearing members 3 and 4 are externally fitted to the shaft member 1, respectively, and a stator 5 is externally fitted and fixed to a substantially central portion of the shaft member 1. Then, the lead wire 51 led out from the stator 5 is guided and drawn out of the bracket 2, that is, the disk chamber outside 20 through the through hole 11 provided in the shaft member 1.

The hub member 8 is made of an aluminum material having high processing accuracy and easy processing, and has a substantially bell shape. At the upper part of the hub member 8, the outer peripheral surface of the outer ring of the bearing member 3 and the inner peripheral surface 83 of the hub member 8 are fixed, and at the lower end of the hub member 8, the outer peripheral surface of the outer ring of the bearing member 4 and the inner part of the hub member 8. Perimeter 84
Are fixed via a bush member 41 (spacer) and the auxiliary yoke 7. Thereby, the hub member 8 is rotatably supported relative to the shaft member 1 and the bracket 2. The rotor magnet 6 located inside the hub member 8 and provided on the inner peripheral surface of the auxiliary yoke 7
The hub member 8 is arranged so as to face the stator 5 fixed to the shaft member 1, and the hub member 8 is rotated by the relative rotation between the rotor magnet 6 and the stator 5. It has a so-called outer rotor type motor structure. The auxiliary yoke 7 is provided to prevent magnetic flux from leaking from the rotor magnet 6 to the outside of the hub member 8.

On the outer surface of the hub member 8, four disks 32 are stacked and mounted via spacers 31. Then, the disc 32 is integrally fixed to the hub member 8 by screwing the clamp member 34 into the screw hole 81 of the hub member 8 with the mounting screw 30.

Numerals 9 and 9 denote magnetic fluid seal mechanisms, which are arranged outside the bearing members 3 and 4 in the axial direction. Magnetic fluid seal mechanism 9,
Reference numeral 9 denotes a magnetic circuit unit in which a donut-shaped magnet 92 is sandwiched between ferromagnetic pole pieces 92 and 93, and a magnetic fluid 94. The donut-shaped magnet 92 is magnetized in the axial direction, for example, with N pole and S pole,
By sandwiching between the pole pieces 91 and 93, the corresponding pole pieces are magnetized with N pole and S pole.

When this magnetic circuit unit is disposed axially outside the bearing members 3 and 4 and the pole pieces 91 and 93 are opposed to and close to the shaft member 1 made of a ferromagnetic material, the magnetic circuit with the shaft member 1 is formed. It is formed. By filling and holding the magnetic fluid 94 in the minute gap between the pole pieces 91 and 93 and the shaft member 1, a magnetic fluid seal layer is generated, and the bearing members 3 and 4 and the space in the disk chamber 10 are partitioned. . In addition, the lubricating oil contained in the bearing members 3 and 4 and the unclean air retained inside the hub receiving member 8 are prevented from flowing out and diffusing into the space in the disk chamber 10.

Among the magnetic fluid seal mechanisms 9 and 9, in the magnetic fluid seal mechanism 9 located on the upper side in the axial direction of the hub member 8, the magnetic circuit unit has a protruding portion provided in a ring shape at the upper end of the hub member 8. It is fixed to the inner peripheral surface 83 of 82. In the specific example, the clamp member 34 is mounted on the radially outer side facing the inner peripheral surface 83 of the hub member 8, that is, on the outer side of the protruding portion 82 of the hub member 8.
35 (acting as a magnetic shield means) inner peripheral surface 36,
The entire circumference is in contact with the outer peripheral surface 85 of the projection 82.

By using a ferromagnetic material, for example, the clamp member 34 operates as follows. The magnetic flux B leaked from the magnetic circuit unit passes through the protruding portion 82 of the hub member 8 made of non-magnetic material aluminum, and then the clamp member
It is converged by the magnetic circuit formed by the bent portions 35 of 34 and does not diverge. The leakage magnetic flux B is applied to the bent portion 35.
Therefore, the magnetic field due to the leakage magnetic flux B is not generated to the outer side in the radial direction, that is, the area of the disk 32, and thus does not reach the movable area of the magnetic head (not shown). Thereby, stable read / write performance can be maintained. The bent portion 35 also functions as a guide for attaching the clamp member 34 to the hub member 8, and the clamp member 35
34 Alignment work becomes easy.

FIG. 2 shows a second embodiment of the magnetic disk drive according to the present invention.
FIG. 1 is a cross-sectional view of a magnetic disk drive in which, for example, two 3.5-inch magnetic disks are mounted. As in FIG. 1, the same members are denoted by the same reference numerals.

In FIG. 2, an outer rotor type motor structure similar to that shown in the first specific example is provided, and the hub member 8 is driven to rotate. The hub member 8 is integrally formed of an aluminum material of a non-magnetic material, and the magnetic fluid sealing mechanism 9 is positioned on the inner peripheral surface of a ring-shaped projection 82 provided on the upper side of the hub member 8 in the axial direction. It is fixed. The clamp member 34 is made of a ferromagnetic material, for example, an electromagnetic steel plate, is formed in an inverted U-shaped cross-section, and has an outer peripheral end provided with an operating portion 34a acting on the magnetic disk 32. An annular shield portion 35 for shielding magnetic flux is provided at the peripheral end as described later. The clamp member 34 is mounted by screwing the mounting screw 30 to the hub member 8 therethrough. By attaching the clamp member 34, the magnetic disk 32 is fixed to the hub member 8 as required. When the clamp member 34 is thus mounted, as shown in FIG. 2, the annular shield portion 35 is located in the annular concave portion 89 provided outside the projecting portion 82 of the hub member 8, so that the following operation and effect are obtained. Is achieved. That is, the magnetic flux B leaking from the magnetic circuit unit of the magnetic fluid seal mechanism 9 is
The light passes through the protruding portion 82 and is converged by a magnetic circuit formed by the annular shield portion 35 (acting as a magnetic shield means), and therefore does not reach the disk 32. Also, the second
In the embodiment, the annular shield portion 35 extends inward in the axial direction of the hub member 8, and therefore reduces the height dimension of the hub member 8 as compared with the first embodiment, and also includes a mounting screw. 30
The effective length of the screw hole of the hub member 8 can be substantially increased. Further, in the second specific example, a labyrinth seal mechanism is employed at the lower end side of the hub member 8 without using a magnetic fluid seal mechanism. The seal mechanism at this portion is not limited to a magnetic fluid seal mechanism, a labyrinth seal mechanism, and the like. In this specific example, as a labyrinth seal mechanism, a ring-shaped protruding portion 23 provided on the inner surface of the bracket 2 and a concave groove 44 provided on the outer surface (lower surface) of the bush 41 over the entire circumference are arranged close to each other. It is arranged. Further, the lower side surface 86 of the flange portion of the hub member 8 and the inner side surface 22 of the bracket 2
Similarly, the lubricating oil and the like are disposed close to each other, thereby substantially preventing the lubricating oil or the like scattered from the bearing member 4 from flowing into the disk chamber 10.

The specific examples of the magnetic disk drive according to the present invention have been described above. However, the present invention is not limited to such specific examples, and various modifications and modifications can be made without departing from the scope of the present invention.

For example, the hub member 8 uses an aluminum material as the non-magnetic material, but may use stainless steel, a resin material, or the like. The location of the hub member 8 interposed between the magnetic circuit unit of the magnetic fluid seal mechanism 9 and the annular shield portion 35 of the clamp member 34 has been described using the projection 82, but the projection 82 is a hub member. The shape and dimensions are not limited in any way as part of FIG.

Further, the clamp member 34 is not limited to the above-described material as long as it is a ferromagnetic material, and can be arbitrarily selected. Since the annular shield 35 of the clamp member 34 substantially shields the magnetic flux B leaking from the magnetic circuit unit, at least the annular shield 35 may be made of a ferromagnetic material.
The shapes of the clamp member 34 and the annular shield portion 35 are also arbitrary. Further, an annular ring member constituting the magnetic shield means may be formed separately from the clamp member, and the annular ring member may be housed in the annular recess 89 of the hub member 8.

In addition, the shape and combination of the magnetic fluid sealing mechanism, the number thereof, the configuration method of the bearing member, the dimensions of the disk, and the number of mounted disks can be freely designed.

〔The invention's effect〕

The present invention has the above-described configuration, and has the following effects.

The magnetic flux leaking from the magnetic fluid seal mechanism is shielded by the magnetic shield means, so that the magnetic flux can be read / read by the magnetic head.
Do not interfere with writing. Therefore, it is possible to obtain a highly reliable magnetic disk drive which maintains a predetermined magnetic fluid sealing performance, does not contaminate the disk chamber, and has a stable performance of the magnetic head.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a first specific example of a magnetic disk drive according to the present invention. FIG. 2 is a sectional view of a magnetic disk drive showing a second specific example according to the present invention. FIG. 3 is a sectional view showing a conventional magnetic disk drive. DESCRIPTION OF SYMBOLS 1 ... Shaft member 2 ... Bracket 3, 4 ... Bearing member 5 ... Stator 6 ... Rotor magnet 8 ... Hub member 9 ... Magnetic fluid sealing mechanism 30 ... Mounting screw 32 ... Magnetic disk 34 ... Clamp member

Claims (2)

(57) [Claims] A magnetic disk; a spindle motor for rotating the magnetic disk in a predetermined direction; and a clamp member for attaching the magnetic disk to the spindle motor. A hub member rotatably supported and having the magnetic disk mounted thereon, a rotor magnet mounted on the hub member, a stator disposed facing the rotor magnet, and grease from the bearing means. And a magnetic fluid seal mechanism for preventing scattering, wherein a magnetic magnetic shield means comprising a part of the clamp member is provided radially outward of the magnetic fluid seal mechanism. A magnetic disk drive, which is provided. 2. The end wall of the hub member has an annular recess formed on the outer side thereof opposite to the portion where the magnetic fluid sealing mechanism is provided, and the clamp member has an annular recess located in the annular recess. 2. The magnetic disk drive according to claim 1, further comprising an annular shield portion for shielding magnetic flux from the magnetic fluid sealing mechanism.