JPH10234154A - Bearing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a bearing device which can maintain the surface runout, surface inclination, and surface height of a turntable surface with high accuracy with respect to a temperature change or a wide rotational speed change, has strength against an impact, even if it is of thin portable type, and is suitable for spindle motor used for thin-type high density disc storage device, in a spindle motor which is rotated with a disc placed on the turntable surface. SOLUTION: This thin spindle motor, which turns a disc, is provided with a rotating shaft 1, that is formed on rotator side and fixed at a thrust pad bush 3 to which a turntable 4 is fastened, and a fixed bearing 2 which is formed on stator side, involves a shaft-inserting hole in which the rotating shaft 1 is inserted, supported rotatably by inserting the rotating shaft 1 in the inserting hole, and involves a thrust-bearing end surface 2a for slide-supporting the thrust- receiving bush end surface 3a of the thrust pad bush 3.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a bearing structure for a thin disk motor which satisfies severe specifications of squareness and turntable surface deflection.

[0002]

2. Description of the Related Art Conventionally, a direct drive type spindle motor such as a record player, a CD player, a floppy disk drive, a hard disk drive, and an optical disk drive satisfies severe specifications of shaft perpendicularity and turntable surface runout. Needed.

There was no major problem when the thickness of the motor was large and the bearing span could be long, but at the stage when the drive unit was shifted to a small, thin, and portable type, the motor was extremely small, including a turntable, at 10 mm or less. Thin demands came out.

However, a thin motor can be made relatively easily with a motor that receives side pressure such as a belt or a gear. However, a disk motor receives a thrust load and prevents the turntable from oscillating, so that it does not fall down. Since it had to be maintained, it was difficult to make it thin.

FIG. 3 shows an example of a conventional spindle motor. In FIG. 3, 11 is a rotor shaft, 12 is a bearing, 13 is a rotor bush, 4 is a turntable, 5 is a rotor magnet, 6 is a stator coil, 7 is a motor mounting base, and 8 is a thrust bearing.

As shown in FIG. 3, the bearing of the spindle motor has a structure of, for example, two ball bearings, a sleeve metal, a combination of a ball bearing and a sleeve metal, and the like. The mainstream configuration is a multipoint receiver with a number of balls, or a point receiving configuration in which the shaft end face is formed as a convex spherical R surface and received on a flat surface or a concave spherical R surface.

The run-out accuracy of the turntable surface has been related to the relationship between the radial bearing span, the clearance between the shaft and the bearing, and the perpendicularity between the rotor rotating shaft and the turntable surface. Therefore, it has been difficult to maintain high precision runout accuracy when the bearing span is shortened. In addition, since the contact area of the thrust bearing has a small contact area, the thrust load is concentrated on a small area and a large pressure is applied.

With the increase in the density of the disk storage device, it has become an issue to reduce the run-out / fall-down / height tolerance of the turntable surface and maintain high accuracy. On the other hand, the bearing length is inevitably shortened with the reduction in thickness, and in the configuration related to the bearing length, the processing accuracy has exceeded the limit, and a configuration that can maintain high accuracy without relying on the bearing span has been desired. . In addition, it is compatible with multimedia, and spindle motor is 200rpm ~
For a wide range of rotation speeds such as 6000 rpm, it is required to maintain the accuracy of swing and fall.

Since the conventional bearing configuration is a point bearing, an indentation is apt to occur particularly against an impact load. The ball bearing is a multi-point bearing. Because of the rolling movement, large vibrations and abnormal noises appeared, and market complaints such as tracking errors occurred, resulting in a problem with the life. Also in the case of the shaft end face bearing, the partial indentation accelerates abrasion and causes the life to be remarkably deteriorated.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned drawbacks and to provide a thin disk motor bearing device with high turntable surface runout / fall / high accuracy.

More specifically, the present invention relates to a spindle motor for rotating a disk placed on a turntable surface. An object of the present invention is to provide a bearing device which is maintained with high precision against a change and is resistant to impact even in a thin portable type, and is suitable for a spindle motor for a thin high-density disk storage device.

[0012]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned conventional problems, and the invention according to claim 1 is provided on a rotor side of a thin spindle motor for rotating a disk. , The rotating shaft 1 fixed to the thrust receiving bush 3 to which the turntable 4 is fixed
And a shaft insertion hole which is provided on the stator side and into which the rotary shaft 1 is inserted. The rotary shaft 1 is inserted into the shaft insertion hole to rotatably support the shaft insertion hole. And a fixed bearing 2 having a thrust bearing end face 2a for slidably supporting 3a.

Further, according to the present invention, the disk mounting surface 4a of the turntable 4 and the thrust receiving bush end surface 3a
, A parallelism reference surface is provided, and a thrust bearing end surface 2a of the fixed bearing 2 and a motor mounting surface 7a of the mounting base 7 fixed to the fixed bearing 2 are provided with a parallelism reference surface.
Runout is determined by the flatness of the thrust bearing end face 2a, the flatness of the thrust receiving bush end face 3a, and the parallelism between the thrust bearing end face 2a and the disc mounting face 4a, and the inclination of the disc mounting face 4a is reduced by the motor mounting face 7a. And the thrust bearing end surface 2a.

According to a third aspect of the present invention, the thrust receiving bush end face 3a and the thrust bearing end face 2a are in contact with each other through a ring surface via grease or oil, and the magnet 5 and the stator fixed to the turntable 4 are fixed. The rotor is rotated along the ring surface in the thrust direction by applying a thrust load sufficiently larger than the radial load by the attraction force with the magnetic attraction material on the side.

Further, in the invention according to claim 4, a dynamic pressure generating groove is provided on one of the sliding ring surfaces of the thrust receiving bush end face 3a and the thrust bearing end face 2a.

Further, in the invention according to claim 5, the sliding ring surfaces of the thrust receiving bush end face 3a and the thrust bearing end face 2a are mirror-finished and surface-treated to increase the hardness of only the surface.

[0017]

According to the bearing device of the first aspect, the thrust load receiver is not a conventional point bearing but a surface bearing.
By making it easier to reduce the thickness and increasing the contact area,
Vibration and abnormal noise caused by indentation due to impact load, which was a problem with spot receiving, are reduced, and runout accuracy is improved.

According to the bearing device of the second aspect, the thickness of the disk can be easily reduced by adopting a configuration in which the accuracy of the run-out / fall of the disk surface is determined by the plane parallelism without depending on the bearing length or clearance. Runout / fall / height dimensional accuracy is improved.

According to the bearing device of the third aspect, the rotor is rotated along the ring surface in the thrust direction by applying a thrust load that is sufficiently larger than the radial load. It can be managed on the thrust bearing surface without depending on the length or clearance.

According to the bearing device of the fourth aspect, since the dynamic pressure generating groove is provided on one of the sliding ring surfaces of the thrust receiving bush end surface 3a and the thrust bearing end surface 2a, frictional resistance during rotation is reduced. It is possible to reduce the wear, reduce the wear and extend the life.

According to the bearing device of the fifth aspect, the sliding ring surfaces of the thrust receiving bush end surface 3a and the thrust bearing end surface 2a are mirror-finished and surface-treated to increase the hardness of only the surface. Even materials that are easy to scratch are not easily scratched,
It is hard to wear and can extend the life.

[0022]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a sectional view illustrating a bearing device according to an embodiment of the present invention, and FIG. 2 is a diagram illustrating a dynamic pressure generating groove according to another embodiment of the present invention.

In the thin spindle motor for rotating a disk shown in FIG. 1, a turntable 4 to which a magnet 5 is fixed is fixed to a thrust receiving bush 3 on a rotor side.
Is inserted and fixed. The stator has a shaft insertion hole into which the rotary shaft 1 is inserted. The rotary shaft 1 is inserted into the shaft insertion hole to rotatably support the shaft. The thrust receiving bush 3 has a thrust receiving bush end face 3a. A fixed bearing 2 having a thrust bearing end face 2a for slidingly supporting the motor is fixed to a motor mounting base having a rotation drive coil 6.

In FIG. 1, the degree of parallelism between the disk mounting surface 4a of the turntable 4 and the thrust receiving bush end surface 3a is 1
Using a rotor controlled with a tolerance of 0.05 mm in height and height,
The thrust receiving bush end face 3a is provided with a recess as shown in FIG. 2 so that when the number of rotations increases, dynamic pressure acts to reduce the thrust pressure and not increase the PV value.

The thrust receiving bush end face 3a is subjected to a surface treatment to have a surface hardness of Hv 1000 or more. A stator was used in which the degree of parallelism between the motor mounting surface 7a and the thrust bearing end surface 2a was 1 minute and the height tolerance was 0.05 mm.

Further, the thrust bearing end surface 2a, which is the thrust receiving surface, and the thrust receiving bushing end surface 3a are brought into contact with each other by sandwiching grease, and grease lubrication is performed. With such setting, the clearance between the shaft 1 and the bearing 2 is set to 8
μm, bearing length 2mm, assembling with a perpendicularity of 5 minutes between shaft 1 and thrust receiving bushing end face 3a. As a result, turntable surface runout of 2 minutes or less, surface fall of 2 minutes or less, height variation of 0.1 or less. Performance was obtained stably. The life is related to surface roughness and surface hardness and can be easily set.

As described above, the thrust load is received on the flat ring surface, and the rotor rotates in the flat shape, whereby
A bearing device independent of bearing span, bearing clearance, and squareness can be configured. In this case, the following conditions are required.

That is, thrust load >> radial load.
The relationship between the bearing clearance, the bearing length, and the perpendicularity between the shaft and the thrust receiving surface of the bush is as follows: When the clearance between the shaft and the bearing is δ, the bearing length L, and the perpendicularity θ between the shaft and the turntable surface is δ / L. ≧ θ.

If the clearance between the shaft and the bearing is small, the clearance is increased because the runout accuracy is determined by the bearing span, as in the conventional bearing configuration. However, if the clearance is too large, the shaft runout is deteriorated, so there is a limit. By receiving a thrust load on the flat ring surface, the load receiving area increases, which is good, but this increases friction resistance (increases bearing loss), and the faster the rotation, the greater the operating current, heat generation,
This leads to increased wear. When the rotation speed is high, the use of dynamic pressure reduces the pressure P when the rotation speed is increased, and prevents the PV value from being increased, which is effective in abrasion resistance. In addition, if surface hardness is increased by surface treatment and surface roughness is improved, indentations are less likely to occur, and even a material that is easy to process has an effect on abrasion resistance.

In this embodiment, since the bearing length has no effect on the run-out, the press-fit allowance has been shortened or the like in order to secure the bearing length, but the press-fit allowance can be sufficiently increased. And improved mechanical strength and impact resistance.

As described in detail above, in the configuration of the present invention, the runout / falling accuracy of the turntable surface is determined only by the thrust receiving surfaces on the rotor side and the stator side, and the radial bearing merely determines the position of the shaft. Since a radial bearing for maintaining the runout / falling accuracy is not required, the bearing span becomes longer and becomes a hindrance, and can be said to be a configuration suitable for thinning.

What is ultimately required is the parallelism between the mounting surface of the mounting base and the turntable surface. Conventionally, the perpendicularity on the stator side and the perpendicularity on the rotor side are strictly controlled.
Shaft outer diameter and bearing inner diameter were also strictly managed, and a contrivance was made to maintain parallelism through squareness and diameter.
Easy to manage. In addition, since the thrust receiver is a surface support, the contact area is increased, and indentations are less likely to be formed due to an impact or the like, thereby increasing market reliability.

[0033]

According to the present invention, as described in detail in the embodiments, the thrust load receiver is not a conventional point bearing but a surface bearing, and the accuracy of the disk surface runout / fall is determined by the bearing length and clearance. In this case, the thickness is easily reduced because of the plane parallelism, and the increased contact area reduces vibration and abnormal noise caused by indentation due to impact load, which was a problem with spot bearings. It is possible to provide a bearing device suitable for a spindle motor for a thin high-density disk storage device with improved fall and height dimensional accuracy.

[Brief description of the drawings]

FIG. 1 is a sectional view illustrating a bearing device for a thin disk motor according to an embodiment of the present invention.

FIG. 2 is a diagram illustrating a bearing device according to another embodiment of the present invention.

FIG. 3 is a cross-sectional view illustrating a conventional thin disk motor bearing device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Shaft 2 Bearing 2a Thrust bearing end face 3 Thrust receiving bush 3a Thrust receiving bush end face 4 Turntable 4a Disk mounting surface 5 Magnet 6 Coil 7 Mounting base 7a Motor mounting surface

Claims (5)

[Claims] In a thin spindle motor for rotating a disk, a shaft provided on a rotor side and fixed to a thrust receiving bush to which a turntable is fixed is provided, and the shaft is provided on a stator side and the shaft is inserted. A fixed bearing having a shaft insertion hole, the shaft being inserted into the shaft insertion hole, rotatably supporting the shaft, and having a thrust bearing end surface slidably supporting a thrust receiving bush end surface of the thrust receiving bush. A bearing device comprising: 2. A motor mounting surface of a mounting base fixed to a thrust bearing end surface of the fixed bearing and a fixed base, wherein a parallelism reference surface is provided on a disk mounting surface of the turntable and an end surface of the thrust receiving bush. Is provided with a parallelism reference surface, and the deflection of the disk mounting surface is determined by the flatness of the thrust bearing end surface, the flatness of the thrust receiving bush end surface, and the parallelism between the thrust bearing end surface and the disk mounting surface. 2. The bearing device according to claim 1, wherein the disc mounting surface is tilted by the parallelism between the motor mounting surface and the thrust bearing end surface. 3. An end surface of the thrust receiving bush and an end surface of the thrust bearing are in contact with each other via a ring surface via grease or oil, and an attraction force between the magnet fixed to the turntable and the magnetic attraction member on the stator side. Or wherein the rotor is rotated along the ring surface in the thrust direction by applying a thrust load sufficiently larger than the radial load by a preload means in the thrust direction by a spring material. 2. The bearing device according to 2. 4. The bearing device according to claim 1, wherein a dynamic pressure generating groove is provided on one of the sliding ring surface of the thrust receiving bush end surface and the thrust bearing end surface. 5. The end surface of the thrust receiving bush and the sliding ring surface of the end surface of the thrust bearing are mirror-finished and surface-treated to increase the hardness of only the surface. Or the bearing device according to 4.