JPH0542755B2 - - Google Patents

Description

[Detailed Description of the Invention] (a) Technical Field of the Invention The present invention relates to a magnetic disk device that performs recording and reproduction on a rotationally driven medium, and in particular, a magnetic disk device in which a magnetic seal is provided on the rotating shaft of a spindle unit that rotates the medium. Related to magnetic disk devices.

(b) Prior Art and Problems A magnetic disk device that selects a predetermined track to be recorded and reproduced on a rotating disk-shaped medium and performs recording and reproduction using a magnetic head is constructed as shown in FIG. There is. FIG. 1 schematically shows a conventional magnetic disk device; a is a perspective view, b is a side view, and c is a detailed view of a magnetic seal.

In a conventional magnetic disk device, as shown in a and b, disk-shaped media are mounted on hubs 5A and 5B fixed to rotating shafts 2A and 2B of a spindle section 2, which are rotated by the rotational drive of a DC motor 3. A plurality of media 4 are fixed at predetermined intervals, and the media 4 are
It is rotated about the axis in the direction shown by arrow A. The shaft 2A in case a is provided so as to pass through the cover 1A, and both ends are rotatably held by bearings 7 fixed to the cover 1A, and the rotating shaft 2B in case b is attached to the frame 10. It is rotatably held by fixed bearings 7A and 7B via a fixed bearing 11. bearing 7
B is the rotating shaft 2B to which the compressive force of the spring 12 is applied.
In order to prevent play from occurring in the locking of the rotating shaft 2,
An earth bar 15 for removing static electricity is in contact with the lower end of B.

Recording and reproduction of the medium 4 is carried out by rotating the medium 4 to levitate a magnetic head (not shown) fixed to the actuator mechanism, and to create a space between the recording surface of the medium 4 and the slider of the magnetic head by a predetermined distance. is formed and recording/reproduction is performed. This gap is designed to be as small as possible in accordance with high-density recording.

Therefore, it is important that the sealed chamber I in which the medium 4 is located has a completely sealed structure so that dust from outside air is not mixed in. In the case of a, the cover 1A has an integral structure, and a magnetic seal 6 is provided in the gap between the through hole of the cover 1A and the rotating shaft 2A, and in the case of b, the cover 1B is attached to the frame 10.
Similarly to the above, a magnetic seal 6 is provided in the gap between the bearing 11 and the rotating shaft 2B, and the sealed chamber I is formed to be shielded from the outside air.

Furthermore, fins 1A-1 and 1B-1 are provided on the outer peripheral surfaces of the covers 1A and 1B so that heat generated in the sealed chamber I due to the rotation of the medium 4 is radiated. Furthermore, in order to adjust the pressure in the sealed chamber I, for example b
As shown in FIG. 2, a breathing filter 13 and a breathing hole 14 are provided on the outer periphery of the cover 1B to take outside air into the sealed chamber I, and the outside air is filtered by the breathing filter 13 and taken in.

The magnetic seal 6 has N of the magnet 6A, as shown in c.
A ring-shaped yoke 6B with S polarity is connected to the rotating shaft 2.
The magnet 6A is fixed to the cover 1A or the bearing 11 by protruding and fixed to the outer periphery of the magnets A and 2B. A magnetic flux shown by an arrow G is formed by this magnet 6A, and by injecting a magnetic fluid 6C formed by mixing magnetic powder and oil into the middle of the yoke 6B, the magnetic fluid 6C flows along the magnetic flux. The outer periphery of the rotating shafts 2A, 2B and the yoke 6 are restrained.
A film is formed in the gap E between the tip of B and the tip. When such a film is formed, it blocks outside air from flowing into the sealed chamber I from the outside O as shown by arrows C and F.

This coating is formed so that it will not be destroyed by the viscosity of the magnetic fluid 6C and the binding force of the magnetic flux even if the rotating shafts 2A, 2B are rotated as shown by the arrow A.

However, when the temperature rises due to heat generation,
The viscosity of the magnetic fluid 6C becomes weaker, and if the rotating shafts 2A, 2B are left in a horizontal position for a long time as shown in c, the magnetic fluid 6C accumulates on the lower surface due to gravity, causing the rotating shafts 2A, 2B to become weaker. Arrow F when rotating 2B
This had the disadvantage that splashes of magnetic fluid 6C were generated as shown in FIG.

When droplets of magnetic fluid 6C are generated in this way,
There was a problem in that the splashed magnetic fluid 6C adhered to the recording surface of the medium 4, causing problems such as head crashes.

(c) Purpose of the Invention The purpose of the present invention is to prevent the magnetic fluid splashed from a magnetic seal from entering the sealed chamber in which the medium is placed, and to eliminate the above-mentioned problems, and to check the state of splashing and assemble it. This allows for later replenishment.

(d) Structure of the Invention An object of the present invention is to provide a frame having a cylindrical bearing protruding into a sealed chamber covered by a cover, and a cylindrical bearing provided on the inner periphery of the bearing in such a magnetic disk device. A rotating shaft that is rotatably held by a bearing and penetrates from the sealed chamber toward the outside of the frame, and a magnetic seal that blocks outside air flowing into the sealed chamber through a gap between the rotating shaft and the bearing. and a labyrinth structure formed between a hub that is locked to the rotating shaft and a presser fitting that is locked to the tip of the bearing, and the labyrinth structure, the bearing, and the magnetic seal. The labyrinth structure, the bearing, and the magnetic seal are arranged in this order along the penetrating direction of the rotating shaft.

With this configuration, the above-mentioned problems are solved.

(e) Embodiments of the Invention The present invention will be described in detail below with reference to FIG.
FIG. 2A is a side view of an embodiment of the magnetic disk device according to the present invention, and FIG. 2B is a detailed view of a magnetic seal.

A hub 25 is fixed to one end of the rotating shaft 22A of the spindle part 22, a rotor 23A of a DC motor 23 is fixed to the other end, and a cylindrical bearing 11 whose one end is fixed to the frame 20 is provided in the middle part. It is rotatably held by bearings 7A and 7B.

A plurality of media 4 are fixed to the hub 25 at predetermined intervals, and a coil 23B is attached to the outer periphery of the rotor 23A.
is fixed. The inner side of the bearings 7B, 7B provided in the bearing 11 is press-fitted into the rotating shaft 22A, and the outer side of the bearing 7B is held by a presser fitting 29 fixed to the bearing 11 and the compressive force of the spring 12, so that they are engaged. It has been stopped. A ring-shaped groove is formed in this holding fitting 29, and when it is locked to the tip of the bearing, it matches the ring-shaped protrusion provided on the inner wall of the hub 25, forming a labyrinth structure. The airflow flowing between the hub 25 and the hub 25 meanderes due to the minute gaps between the grooves and the protrusions, and is formed to provide a predetermined flow resistance. In addition, magnetic seal 6
is fixed between the fixed location of the bearing 7A and the fixed location of the rotor 23. Cover 21 is medium 4
The outer periphery of the cover 21 includes a heat dissipation fin 21A, a breathing filter 13 and a breathing hole 14 that take in outside air, and a desiccant that absorbs the humidity inside the sealed room I. A case 21B is provided in which is housed.
Further, an earth bar 28 for removing static electricity is provided at the tip of the rotating shaft 22A.

Therefore, the medium 4 is rotated by rotating the rotor 23A in the direction of arrow A around the DD axis.
It is constructed so that recording and reproduction are performed by the aforementioned magnetic head.

As the medium 4 is rotated, the air in the sealed chamber I is blown by centrifugal force from the vicinity of the rotating shaft 22A to the outer periphery of the medium 4, and the blown air is pressed against the inner wall of the cover 21. A portion of the pressed air flows into the vicinity of the rotating shaft 22A, and is further circulated so as to be blown around the outer circumference of the medium 4. Therefore, the pressure is high at the outer circumference of the medium 4, and the rotation shaft 22
The pressure is low near A. Furthermore, it is necessary to adjust the difference between the internal pressure of the sealed chamber I and the pressure of the outside air, which is caused by the temperature difference between the outside air and the sealed chamber I. This adjustment is performed by taking in outside air into the sealed chamber I or by discharging air from the inside of the sealed chamber I to the outside. For this intake or discharge, the gap between the rotating shaft 22A and the bearing 11 is shielded by the magnetic seal 6 so that the outside air does not flow in or discharge as shown by the arrow C, so the breathing hole 14 and a respiratory filter 13.

With this configuration, when the difference between the internal pressure and the external pressure of the sealed chamber I suddenly changes, air that is about to flow into the gap between the inner circumference of the bearing 11 and the outer circumference of the rotating shaft 22A is prevented. The flow is suppressed by the holding fitting, and it is possible to prevent pressure from being applied to the magnetic seal 6 due to the sudden air flow, and it is possible to prevent the magnetic fluid 6C from being splashed as much as possible as described above. Even if the magnetic fluid 6C is splashed, as shown in b, the magnetic fluid 6C splashed in the direction of arrow _F1 will be blocked by the bearing 7A, and the magnetic fluid 6C splashed in the direction of arrow _F2 will be blocked by DC.
Since it is on the motor side, the magnetic fluid 6C is prevented from being scattered inside the sealed chamber I.

(f) Effect of the Invention As explained above, the present invention provides the bearings 7A and 7B that rotatably hold the rotating shaft 22A and the magnetic seal 6 that shields the gap E fixed to the bearing 11. The fixed location of the bearing 7A is located on the outside of the sealed chamber I from the fixed location of the bearing 7A, and the labyrinth structure is designed to suppress airflow flowing through the gap between the bearing 11 and the rotating shaft 22A. This is what I did.

Therefore, the magnetic fluid 6C of the magnetic seal is prevented from being splashed as much as possible, and even if it is splashed, it is blocked by the bearing 7A and is no longer scattered inside the sealed chamber I as in the conventional case. Therefore, problems such as head crushing can be prevented and the practical effect is great.

[Brief explanation of the drawing]

FIG. 1 shows an outline of a conventional magnetic disk device; a is a perspective view, b is a side view, and c is a detailed view of a magnetic seal; FIG. 2 a is an embodiment of a magnetic disk device according to the present invention. Side view, b shows a detailed view of the magnetic seal. In the figure, 1A, 1B, 21 are covers;
2, 22 are spindle parts, 2A, 2B, 22A are rotating shafts, 3, 23 are DC motors, 4 is a medium, 5A,
5B, 25 is a hub, 6 is a magnetic seal, 7, 7A,
7B is a bearing, 28 is an earth bar, 29 is a holding fitting, 11 is a bearing, 12 is a spring, 13 is a breathing filter, and 14 is a breathing hole.

Claims (1)

[Claims] 1. A frame having a cylindrical bearing protruding into a sealed chamber covered by a cover, and a frame that is rotatably held by a bearing provided on the inner periphery of the bearing. A rotating shaft that penetrates from the sealed chamber toward the outside of the frame, a magnetic seal that blocks outside air flowing into the sealed chamber through a gap between the rotating shaft and the bearing, and a hub that is locked to the rotating shaft. a labyrinth structure formed between a presser fitting fixed to a tip of the bearing, and each of the labyrinth structure, the bearing, and the magnetic seal extends along the penetrating direction of the rotating shaft. A magnetic disk device characterized in that the labyrinth structure, the bearing, and the magnetic seal are arranged in this order.