JPS5824862B2 - magnetic disk drive - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a magnetic disk drive device that prevents lubricant, sealant, dust, etc. from entering between magnetic disk surfaces.

In order to record and reproduce information at high recording density on a magnetic disk, it is necessary to fly a floating head above the surface of the magnetic disk and maintain a submicron flying gap.

However, if particles such as dust get mixed into the air around the magnetic disk, there is a great risk that they will get stuck in the flying gap and damage the floating head and the magnetic disk.

Furthermore, lubricants such as grease are used in the bearings that rotatably support the magnetic disks, but this has the disadvantage that it scatters and sticks to the surface of the magnetic disks and the floating head, preventing the floating head from flying stably.

A structure conventionally used to eliminate this drawback is shown in FIG.

In FIG. 1, magnetic disks 1 are stacked via a spacing ring 3 having ventilation holes 2 and fixed to a bubble 4.

A filter 6 is installed in the bell-shaped portion 5 of this bubble 4, and this bubble 4 is rotationally driven by a spindle 8 supported by a bearing 7.

When the magnetic disk 1 rotates, the air on its surface rotates as the magnetic disk 1 rotates, causing an outward flow due to centrifugal force.

As a result, an outward flow is generated through the filter 6, so that dust and the like entering from the bearing 1 are captured by the filter 6.

However, at the rotation speed normally used for magnetic disks, ie, 2400 to 3600 revolutions per minute, the air flow in the bell-shaped portion 5 becomes quite turbulent.

Therefore, the flow inside the bell-shaped part mixes particles such as dust, and some of it also mixes with the outward flow at the bottom surface of the magnetic disk and enters the magnetic disk chamber 9 without passing through the filter 6. There is a drawback.

This flow is shown by the arrows in FIG.

This tendency becomes stronger as the filter is made narrower to capture even the finest particles.

This is because the air passage resistance of narrow-mesh filters is large.
This is because the flow rate passing through the filter decreases, and the outward flow at the bottom surface of the magnetic disk becomes relatively strong.

For this reason, in the conventional structure, only a rough filter mesh size of several tens of microns can be applied, and therefore, it is necessary to completely capture enough particles such as dust to safely maintain the floating head floating gap of submicron size. I couldn't do that.

In order to eliminate the drawbacks of the conventional example described above, the present invention provides a magnetic disk drive device having a structure in which fine particles from the bearing can be completely captured by a filter. Explain in detail.

FIG. 2 shows one embodiment of the present invention, in which 1 is a magnetic disk, 2 is a ventilation hole, 3 is a spacing ring, 4' is a bubble,
6 is a filter, 7 is a bearing, 8 is a spindle, 9 is a magnetic disk chamber, 10 is a magnetic fluid seal, 11 is a bearing...Using, 12 is a bearing...A fitting part between the Uzzing 11 and the Bu 4'. be.

The bub 4' of the present invention includes an end plate part 41 fixed to the spindle 8, a cylindrical part 42 on the outer periphery of which the spacing ring 3 and the magnetic disk are installed, and a narrow cylindrical gap on the outer periphery of the bearing nozzle 11. Did...Mating part 1 between Uzing and Bub
2, and a disk portion 43 for forming a

The cylindrical part 42 has a ventilation hole 4 through which air flows from the inside to the outside.
4 is installed so as to connect the spacing ring 30 with the ventilation hole 2.

There are no ventilation holes in the end plate part 41 and the disc part 43, and...
The air inflow passage into the interior of the knob 4' is limited to the fitting portion 12 between the housing and the knob.

In addition, bu 4' is rotationally driven by a spindle,
The narrow cylindrical gap between the fitting part 120 of the housing and the housing is maintained as is, and they do not come into contact with each other.

The first feature of the present invention lies in the installation location of the filter 6.

That is, it is installed inside the spacing ring 3...on the inside of the cylindrical surface of the tube 4'.

By doing so, the conventional bell-shaped portion is not necessary, and a filter with a large area can be used.

Furthermore, even if a centrifugal force due to rotation acts on the filter 6, the filter 6 can be prevented from deforming by simply being pressed against the cylindrical surface of the bub 4'.

The second feature is the fitting portion indicated by 12 between the bearing housing 11 and the housing 4'.

This fitting part maintains a narrow cylindrical gap, and...
Even if the air inside the tube 4' is turbulent, a laminar flow is formed in the gap so that the turbulent flow does not leak to the bottom surface of the magnetic disk.

The conditions for creating laminar flow in this gap are given by the following known formula.

Here, ν is the kinematic viscosity coefficient of the gas, ω is the angular rotational speed, and γ is the radius of rotation.

To give an example of a specific value of h, the working gas is air at normal temperature and pressure, the rotation radius is 10 c1n, and the rotation speed is 3000 r.
If it is pm, then h will be 0.34 mm.

Further, the magnetic fluid seal 10 is provided to prevent outside air containing dust from flowing into the inside of the tube 4' through the bearing 7.

In this way, dust in the outside air can be blocked, but due to evaporation and scattering of the magnetic fluid, fine particles of the magnetic fluid...
Flowing into the inside of the tube 4' is unavoidable.

A turbulent flow is generated inside the knob 4', and the turbulent flow mixes with the air therein.

However, as mentioned above, the bearings...Using 11 and Bushing 4
If the gap at the fitting part with the knob 4' is set to a small value to satisfy the laminar flow conditions, the turbulence of the air inside the knob 4' will be blocked by the gap, and the air containing fine particles will be No leakage to the bottom surface of the magnetic disk occurs due to turbulence components.

Further, the outward flow between the magnetic disks is directed from the bottom surface of the magnetic disk to the fitting portion 1 between the bearing housing 11 and the knob 4'.
2 and into the inside of the knob 4', so as long as a laminar flow is formed within the gap, the flow from the inside of the knob 4' to the bearing 11 and... Air does not flow backward toward the lowermost surface of the magnetic disk through the fitting portion 12 with the disk 4'.

In this way, a flow is created in which all particles entering the knob 4' are captured by the filter 6.

Therefore, the air passage resistance of the filter 6 can be considerably larger than that of the conventional filter.

Further, as described above, according to the present invention, a filter having a larger area than conventional filters can be used, and therefore, a fine-mesh filter capable of trapping submicron particles can be used.

Although a magnetic fluid seal is used in this embodiment, it may be omitted if the cleanliness of the outside air with respect to dust is quite high. Also, scattered particles of lubricant from the bearing 7 are completely captured by the filter.

If the outside air contains a considerable amount of dust, clogging of the filter becomes a problem, but to solve this problem, a structure using a magnetic seal as shown in the embodiment shown in Figure 2 is recommended. Alternatively, it may be constructed as in another embodiment shown in FIG.

In Fig. 3, the fitting portion 12 between the magnetic disk 1, ventilation hole 2, spacing ring 3,... 4', filter 6, bearing 7, bearing 17, and... 4 is shown in Fig. 2. This is the same as the embodiment shown, but a drive motor 13 is attached to the spindle 8, and a closed case 15 is provided to isolate the motor chamber 14 from the outside air.

In this way, there is no flow of outside air into the inside of the tube 4', and the filter 6 only needs to capture the scattered particles of bearing lubricant, which solves the problem of filter clogging. In addition to being installed inside the bubble as in the embodiments shown in FIGS. 2 and 3, the same effect can be achieved by installing it inside the spacing ring.

As explained above, according to the present invention, the air flow becomes laminar at the fitting portion between the bearing and the housing,
All dust and lubricant particles from the bearing pass through the filter installed in the bubble or spacing ring, and since it is possible to use a fine-mesh filter as the filter, submicron particles can be completely removed by the filter. It is possible to realize a high-recording-density magnetic disk drive device in which the floating head can be captured stably, thereby reducing the risk of damage to the floating head or the magnetic disk, and in which the floating head can fly stably.

[Brief explanation of drawings]

Figure 1 is a sectional view of a conventional magnetic disk drive;
The figure is a cross-sectional view of one embodiment of the present invention, and FIG. 3 is a cross-sectional view of another embodiment of the present invention. 1... Magnetic disk, 2... One ventilation hole,
Total... Spacing ring, 4,4'-...P, 41...End plate of b4', 42...
... Cylindrical part of Bu 4', 43... Bu 4'
Disc part, 44... Ventilation hole installed in the cylindrical part 42 of 4', 6... Filter, 7...-
...Bearing, 8...Spindle, 9...
Magnetic disk chamber, 10...Magnetic fluid seal, 1
DESCRIPTION OF SYMBOLS 1---Bearing housing, 12---Bearing fitting part between housing, 13---Drive motor, 14---Motor chamber, 15・−・・−・
Closed case.

Claims (1)

[Scope of Claims] 1. A magnetic disk drive device in which a plurality of magnetic disks are stacked via spacing rings each having a ventilation hole and are attached to a bubble, and the bubble is rotationally driven by a spindle, comprising: the magnetic disks and the spacing ring; a cylindrical part having a ventilation hole that connects with the ventilation hole of the spacing ring when installed on the outer periphery; an end plate part fixed to one end of the cylindrical part with a spindle;
The other end of the cylindrical portion is provided with a bearing consisting of a housing and a disk portion that fits with a gap, and the air inflow passage into the inside of the bubble is formed by fitting the disk portion with the gap. In the department,
The air outflow passage is limited to the vent hole of the bubble, and the cylindrical space in that area is stratified at the clearance fitting part between the bearing housing and the disc part of the bubble. What is claimed is: 1. A magnetic disk drive device characterized in that the magnetic disk drive device is configured with a minute gap so as to form a flow, and a dust trapping filter is installed inside the spacing ring or inside the gap inscribed in the spacing ring. 2. The magnetic disk drive device according to claim 1, wherein the spindle is provided with a magnetic fluid seal.