JPH0648576B2 - Spindle motor - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a spindle motor for rotating a recording disk.

[0002]

2. Description of the Related Art Conventionally, a spindle motor for driving a recording disk has a fixing member, a hub rotatably supported by the fixing member via a pair of bearings, a rotor magnet mounted on the hub, and a fixing member. And a stator mounted on the. Then, a recording disk such as a magnetic disk is mounted on the hub as required, and the recording disk is rotated in a predetermined direction by the mutual magnetic action of the rotor magnet and the stator.

In this type of spindle motor, during rotation of the motor, dust generated in the motor is ejected to the outside by centrifugal force and adheres to the surface of the recording disk of the disk drive device, and accompanying rotation of the recording disk. Since it may collide with the fixed head means and damage the head means,
A dustproof seal structure is provided outside the pair of bearings to prevent damage.

For example, in a magnetic disk drive, the magnetic disk usually has a rotation speed of about 3600 rpm, so that the outer circumference of a 5.25-inch magnetic disk is about 90.
The speed will be km / hour. The dustproof seal structure includes a structure using a magnetic fluid and a structure applying a labyrinth effect.

[0005]

However, the dustproof seal structure (magnetic fluid seal structure) using the magnetic fluid is
Since the magnetic fluid itself is expensive, the cost is high, the shaft is long to install the magnetic fluid seal, it is necessary to improve the precision of parts to prevent the magnetic fluid from scattering, and the actual handling control items are There are many problems such as being troublesome.

On the other hand, in the structure using the labyrinth effect (labyrinth seal structure), gaps having complicated shapes are evenly distributed,
In addition, there are problems that it is necessary to form minutely, complicated processing and high assembly accuracy are required. Therefore, it takes a lot of time and labor for processing and assembling.

An object of the present invention is to provide an excellent spindle motor which can obtain a sufficient dustproof effect with a relatively simple structure.

[0008]

According to the present invention, the sealing means is provided on the outer side of one of the pair of bearings.
The other of the pair of bearings is a shielded bearing, a shield is provided on the outer ring of the other bearing, and a contact member is provided on the side surface of the inner ring of the other bearing so as to contact the contact ring. Extends from the inner ring side to the outer ring side and covers a part of the shield, and the relative rotation of the inner ring and the outer ring generates an air flow between the shield and the contact member. Are substantially sealed.

[0009]

In such a spindle motor, when the hub rotates in the predetermined direction, the outer ring and the inner ring of the shielded bearing rotate relative to each other, and a relatively high-speed air flow flows between the shield of the bearing and the contact member. Occurs.

As a result, due to the action similar to that of a so-called air curtain, dust inside the motor is prevented from going out from the shield of the bearing, and does not enter inside the recording disk drive.

The remaining bearings are reliably dust-proofed by the sealing means.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the spindle motor of the present invention will be described below with reference to the accompanying drawings.

FIG. 1 is a sectional view of a spindle motor for driving a recording disk in which a hub rotates.

The shaft 10 is vertically attached to a frame 12 of a recording disk drive unit by a collar 11 formed at one end, and constitutes a fixing member together with the frame 12.
A hub 13 is rotatably supported on the shaft 10 via a pair of ball bearings 14a and 14b.
As is clear from the drawings, the pair of ball bearings 14a and 14b are shielded bearings, and in the present invention, it is important that at least the shielded bearings be provided with the contact members to be described later.

A recording disk such as a magnetic disk (see symbol D in FIG. 2) is mounted on the outer periphery of the hub 13 and functions as a drive hub. The upper end of the hub 13 is open, and the cover 1 that forms a dust-proof seal structure by sealing the upper end opening of the hub in the opened opening.
5 is provided.

A stator 16 is provided in the middle of the shaft 10, and a rotor magnet 17 is provided on the inner circumference of the hub 13 facing the stator 16.

The washer 18 corresponds to the "contact member" in the claims, and is provided in close contact with the flange 11 and the side surface 19a of the inner ring 19 of the lower shielded ball bearing 14b. There is. 2, the shield is provided on the outer ring 21 of the ball bearing 14b and extends from the outer ring 21 toward the inner ring 19. The washer 18 extends from the inner ring 19 toward the outer ring 21, and the outer periphery thereof is the shield 20 of the ball bearing 14b.
To the side surface 20a of the inner ring 19 and the side surface 19a of the inner ring 19,
A small gap s is formed between the shield 20 and the side surface 20a.
(Usually 0.05 to 0.3 mm). In addition,
The outer diameter of the washer 18 is larger than the inner diameter of the shield 20 and does not hit the outer ring 21, but it is desirable that the outer diameter of the washer be equal to or larger than the pitch circle diameter of the bearing. Figure 2
Inside, 22 is a ball and 23 is a cage.

In the above structure, the hub 13 rotates at high speed around the shaft 10 by the action of the stator 16 and the rotor magnet 17. Accordingly, the outer ring 21 of the ball bearings 14a and 14b and the shield 20 fixed to the outer ring 21 also rotate at high speed. On the other hand, the inner ring 19 does not rotate because it is integral with the shaft 10.
Further, the washer 18 is also integral with the shaft 10 and therefore does not rotate.

In this case, the lower ball bearing 14b
Since the shield 20 rotates at a high speed and the washer 18 is stopped, a high-speed air flow is generated in the gap s between them and the inside and outside of the ball bearing 14b are blocked.

Generally, the high speed rotation of the outer ring 21 causes the grease in the ball bearings 14a and 14b to fly out from the gap between the shields 20 and to be atomized by the centrifugal force to be scattered in the recording disk drive. In the lower ball bearing 14b, the grease flow is prevented by the air flow in the gap s. or,
In the upper ball bearing 14a, since the upper end of the hub 13 is sealed by the cover 15, the grease that is atomized and ejected from the gap of the shield 20 will not be scattered to the outside of the hub 13.

In order to prove the above, FIGS. 5 to 8 show how much grease is actually atomized in the hub with and without the dustproof seal structure of the present invention. 13 is a graph in which it is measured as dust if scattered to the outside.

In each case, the vertical axis represents the numerical value (n) obtained by inhaling the air around the motor at 1 cubic foot (1 ft ³ ) per minute and counting the dust contained therein, and the horizontal axis represents the time (minutes). ) Is shown.

In the measurement, the motor was repeatedly rotated and stopped, and the number of dust particles was counted every minute.

FIG. 5 shows the number of dust particles having a particle size of 0.5 to 5.0 μm around the motor alone without the seal structure of the present invention, and FIG. 6 shows the number of dust particles having a particle size of 5.0 μm or more under the same conditions. Are shown respectively.

FIG. 7 has a cover 15 but a washer 18
0.5 to 5.0 μm around the motor without
8 shows the number of dusts of the same size, and FIG. 8 shows the number of dusts of the same size when the washer 18 is provided in addition to the cover 15. In these cases, the count of dust having a particle size of 5 μm or more was zero.

Comparing these figures, it was found that the number of dust around the motor having the shield structure of the cover 15 and the washer 18 was extremely small and was almost zero.

FIG. 3 shows another embodiment of the present invention. Grease scattered from the upper bearing 14a is blocked by the conventional magnetic fluid sealing means 30 as a sealing means, and scattered from the lower bearing 14b by a washer 18. It has been blocked. According to this type, the shaft 10 can be projected upward.

FIG. 4 shows still another embodiment, in which the flange 11 of the shaft 10 instead of the washer 18 is closely attached to the side surface 19a of the inner ring 19 of the lower ball bearing 14b.
The same effect as the first embodiment is produced. In this case Tsuba 11
Corresponds to the “contact member” in the claims.

In the embodiment described above, the shaft 10
, The inner ring 19 of the bearing fixed to the shaft 10 does not rotate, and the outer ring 21 fixed to the hub 13 rotates. However, the outer ring is fixed and the inner ring together with the shaft is fixed. Of course, it can be applied to the case of rotating.

Further, in the above-mentioned embodiment, the grease scattered in the form of mist from the ball bearing has been described as dust, but it naturally has a dustproof sealing effect against other dust generated in the motor.

Further, the bearing may be a roller bearing other than the ball bearing as long as it has a shield.

[0032]

As described above, according to the spindle motor of the present description, it is possible to reliably prevent dust generated in the motor from scattering to the outside with a simple structure. Therefore, the cost can be reduced by reducing the number of parts and relaxing quality control.

Since the axial dimension of the motor can be shortened, a thin motor can be realized.

On the other hand, if the dimension of the motor in the axial direction is the same as that of the conventional one, the shaft interval can be made longer, so that the runout accuracy is improved.

[Brief description of drawings]

FIG. 1 is a sectional view of a spindle motor according to a first embodiment of the present invention.

FIG. 2 is a partially enlarged view of FIG.

FIG. 3 is a diagram corresponding to FIG. 1 of another embodiment of the present invention.

FIG. 4 is a partially enlarged cross-sectional view of still another embodiment of the present invention.

FIG. 5 is a graph of measurement results of dust around a motor having no seal structure according to the present invention.

FIG. 6 is a graph of measurement results of dust around a motor having no seal structure according to the present invention.

FIG. 7 shows a case where only a cover is provided.

FIG. 8 is a graph showing measurement results of dust around the motor when the dustproof seal structure of the present invention is provided.

[Explanation of symbols]

 10 shaft 11 collar (contact member) 13 frame 14a, 14b bearing 15 cover 18 washer (contact member) 19a inner ring side surface 20 shield 30 magnetic fluid seal

Claims (1)

[Claims] 1. A fixing member, a hub rotatably supported by the fixing member via a pair of bearings, on which a recording disk is mounted, a rotor magnet mounted on the hub, and a rotor magnet mounted on the fixing member. In the spindle motor including the stator, a sealing means is provided on the outer side of one of the pair of bearings, the other of the pair of bearings is a shielded bearing, and the outer ring of the other bearing has a shield. A contact member is provided on the side surface of the inner ring of the other bearing so as to contact the inner ring, and the contact member extends from the inner ring side to the outer ring side to cover a part of the shield. The relative rotation of the inner ring and the outer ring causes an air flow between the shield and the contact member, and the air flow substantially seals the inside and the outside of the other bearing. A spindle motor characterized in that