JPS6357871B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a magnetic disk device, and more particularly to a magnetic disk device comprising a spindle using a magnetic seal.

Conventionally, this type of magnetic disk device has a labyrinth structure with several stages on the opposing surface of the spindle hub part of the spindle that supports and rotates a group of magnetic disks and the housing that supports the spindle via a spindle bearing. This prevents dust from entering the disk enclosure from outside air through the bearing.

However, in the labyrinth structure, there always exists a state in which the resistance of the joint surfaces of the parts constituting the disk enclosure, the resistance of the breathing filter, and the resistance of the bearing are balanced, and dust from the outside air passes through the labyrinth. This has the disadvantage that there is a high possibility that a crushing accident of the magnetic head/magnetic disk will occur, which is fatal to the magnetic disk device.

As a means to solve the above drawbacks, a magnetic seal is provided in the housing above the upper bearing, facing the outer diameter of the spindle shaft, and a minute gap is provided between the outer diameter of the spindle shaft and the inner diameter of the magnetic seal, thereby creating a magnetic field between the two. By forming a magnetic fluid and applying magnetic fluid to the gap portion, external air containing dust passing through the bearing is blocked by the magnetic fluid portion, thereby eliminating any external air from flowing into the disk enclosure.

However, in this structure, the inner diameter of the magnetic seal is smaller than the outer diameter of the upper bearing, so the procedure involves assembling the magnetic seal, spindle shaft, and upper bearing, applying magnetic fluid to the cast, and press-fitting the spindle hub to the spindle shaft. Therefore, in the state of a spindle hub shaft in which the spindle hub and spindle shaft are integrally cast, it is impossible to assemble it, so it cannot be used, and the magnetic fluid application state falls into an unfavorable state due to the press-fit shrinkage fit of the spindle hub. There was a drawback that it was possible.

According to the present invention, the above drawbacks are solved by making the inner diameter of the magnetic seal larger than the outer diameter of the spindle upper bearing of the magnetic disk device, and by providing a tap through hole in the spindle hub that supports the magnetic disk group. However, it is possible to obtain a magnetic disk device in which there is no inflow of outside air into the disk enclosure.

Next, embodiments of the present invention will be described with reference to the drawings. In the magnetic disk device according to the embodiment of the present invention shown in the drawings, a spindle 22, a magnetic circuit 18, a carriage 23, and a cover 8 are mounted on a base plate 21.

The spindle 22 is composed of a spindle shaft 1, a housing 4, bearings 2 and 3, a spindle hub 5, a magnetic seal 6, a rotor 11, and a stator 12. A magnetic disk group 10 is stacked on the spindle hub 5 via a spacer ring 9. The magnetic disk group 10 is fixed to the spindle hub 5 by the clamp ring 7.

The magnetic seal 6 is fixed to the housing 4, and the inner diameter of the magnetic seal 6 is arranged to face the outer diameter of the shaft with a small gap.

A magnetic head 15 is rotatably mounted on the carriage 23, and a circulation filter 14 and a breathing filter 16 are attached to a cover 8 having a breathing hole 17.

The carriage 23 rotates and reciprocates due to the repulsive force between the magnetic field of the magnetic circuit 18 and the magnetic field generated by applying a current to a coil (not shown) connected to the magnetic head 15. The magnetic head 15 attached to the head is rotated and reciprocated.

On the other hand, a magnetic disk group 10 fixed to the spindle hub 5 by a clamp ring 7 is rotated by a motor comprising a stator 12 fixed to the housing 4 and a rotor 11 fixed to the spindle shaft 1.

In the embodiment of the present invention, the outer diameter of the outer ring of the upper bearing 2 whose inner ring is fixed to the spindle shaft 1 is
Because the magnetic seal 6 has a large inner diameter, the spindle hub 5
After the spindle shaft 1 and the spindle shaft 1 are integrally cast and the magnetic seal 6 is assembled into the housing 4, the spindle hub shaft with the upper bearing assembled can be easily assembled into the housing 4 from above.

Further, after the spindle hub shaft is assembled into the housing 4, the magnetic fluid 24 is provided at a location that approximately coincides with a gap portion of the spindle hub 5 where the outer diameter of the spindle shaft 1 and the inner diameter of the magnetic seal 6 form opposing magnetic fields. It can be easily injected through the tap through hole, and after injection, by inserting the set screw 19 and completely closing the tap hole, the base plate 21 and cover 8 where the magnetic disk group 10 and magnetic head 15 are located are sealed. Therefore, the atmosphere inside the disk enclosure 13, which is completely enclosed, is controlled by 24 parts of the magnetic fluid applied between the magnetic seal 6 and the opposing gap of the spindle shaft 1, which absorbs the outside air that is about to flow in through the bearings 3 and 2. Since it is completely shut off, the air is filled with clean air with almost no dust, which has the effect of eliminating crashes caused by dust, which are fatal to magnetic disk drives.

As explained above, the present invention has a simple structure in which the inner diameter of the magnetic seal is made larger than the outer diameter of the upper bearing and the spindle hub is provided with a tap through hole, which makes it easy to assemble the spindle. This has the effect of preventing outside air from entering the disk enclosure and preventing crashes of magnetic disk devices caused by dust.

[Brief explanation of the drawing]

The figure is a partially sectional front view showing an embodiment of the present invention. 1...Spindle shaft, 2...Upper bearing,
3... Lower bearing, 4... Housing, 5... Spindle hub, 6... Magnetic seal, 7... Clamp ring, 8... Cover, 9... Spacer ring, 1
0... Magnetic disk group, 11... Rotor, 12...
...Stator, 13...Disk enclosure,
14... Circulation filter, 15... Magnetic head, 1
6... Breathing filter, 17... Breathing hole, 18...
Magnetic circuit, 19... Set screw, 20... Tap hole, 21... Base plate, 22... Spindle, 23... Carriage, 24... Magnetic fluid, 2
5...Labyrinth.

Claims (1)

[Claims] 1 A magnetic disk group, a spindle rotation mechanism that supports and rotates the magnetic disk group, a housing that supports the spindle rotation mechanism via an upper bearing and a lower bearing, and a housing located above the upper bearing and provided in the housing. In a magnetic disk device comprising a magnetic seal and a magnetic head for recording and reproducing information, the inner diameter of the magnetic seal is larger than the outer diameter of the upper bearing, and the magnetic disk group of the spindle rotation mechanism A magnetic disk device characterized in that a spindle hub on which magnetic disks are laminated is provided with a tap through hole in the axial direction at a radial position communicating with the inner diameter of the magnetic seal.