JPH0729294A - Spindle motor - Google Patents

Abstract

PURPOSE:To prevent the damage and deformation of one bearing outer ring and to stably rotate a disk by absorbing the thermal shrinkage force after heating at the time of shrinkage fitting the one bearing to the inner periphery of a cylindrical part by plural slits formed at the front end of the cylindrical part of a bracket. CONSTITUTION:The plural slits 8 are formed in an axial line direction at the front end of the cylindrical part 4 of the bracket 2 and the one bearing 5 is fitted into the inner periphery of the thermally expanded cylindrical part 2. The cylindrical part 2 after the heating is gradually cooled to shrink and to surely fit the bearing 5. The thermal shrinkage force of this time is absorbed by the elasticity of the slits 8, by which the damage and deformation of the outer ring of the bearing 5 are prevented. Then, the bearing 5 and another bearing 6 are freely rotatably supported. A rotor consisting of a hub 10, yoke 12 and rotor magnet 13 fixed to a shaft 9 is stably rotated by a stator 14. As a result, the recording disk fixed to the rotor is stably rotated without run-out.

Description

Detailed Description of the Invention

[0001]

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

[0002]

2. Description of the Related Art In a conventional spindle motor of a shaft rotation type, a rotor shaft is rotatably supported inside a cylindrical portion of a bracket through a pair of bearings, and a stator is fixed to the outer periphery of the cylindrical portion. The rotor magnet of the rotor is arranged on the outside of the so as to face it. The pair of bearings are arranged at the upper and lower ends of the inside of the cylindrical portion, and in each case, an adhesive is applied to the inner peripheral surface of the cylindrical portion or the outer peripheral surface of the bearing to bond and fix both.

[0003]

In such a conventional structure, when the adhesive is unevenly applied, only the adhesive-applied portion of the outer ring of the bearing is produced when the adhesive is solidified. There is a problem that it is deformed by the shrinkage force of the adhesive. As a result, the roundness of the bearing changes,
The rotor or the recording disk mounted on the rotor rotates while swinging. Therefore, there is a problem that the head cannot normally read the information recorded on the recording disk.

The present invention has been made in view of the above problems of the prior art, and the purpose thereof is to effectively reduce the strain acting on the bearing due to the contraction of the adhesive. It is to provide a spindle motor.

[0005]

In order to achieve the above object, a spindle motor according to the present invention rotates a stator fixed to the outer circumference of a cylindrical portion of a bracket and a pair of bearings inside the bracket. In a spindle motor including a freely supported shaft, a rotor fixed to the shaft, and a rotor magnet arranged at a position of the rotor facing the stator, one of the bearings is fitted in the spindle motor. A plurality of axial slits are radially formed at the tip of the cylindrical portion, and the one bearing is shrink-fitted or press-fitted to the tip of the cylindrical portion. is there.

Further, another spindle motor of the present invention is
A stator fixed to the outer circumference of the cylindrical portion of the bracket, a shaft rotatably supported inside the bracket via a pair of bearings, a rotor fixed to the shaft, and the stator of the rotor facing the stator. In a spindle motor provided with a rotor magnet disposed at a position, a step portion for height regulation of the one bearing is provided at an upper portion of an inner circumference of the cylindrical portion into which the one bearing is fitted. An annular taper inner surface that expands from the step toward the tip side is formed, and an annular clip that encloses the one bearing and holds the one bearing between the step and the step is provided, While forming a plurality of axial slits on the clip,
The taper outer surface facing the taper inner surface is formed on the outer periphery of the clip, and the taper outer surface is adhesively fixed to the taper inner surface.

[0007]

In the former spindle motor of the present invention, in the former case, the outer ring of the bearing is damaged by the shrinkage force of the bracket after the shrink fitting of the cylindrical portion of the bracket and the bearing or the press fit. The slit provided at the tip of the cylinder absorbs the elasticity of the tip of the cylinder. Further, the elasticity of the tip of the cylindrical portion due to the slit allows the bearing to be fitted into the bracket more reliably than in the case without the slit.

In the latter case, with respect to the bearing sandwiched between the upper circumference of the cylindrical portion of the bracket and the clip, distortion due to thermal deformation of the bracket or uneven application of adhesive is caused by the elasticity of the clip due to the slit formed in the clip. Absorbed by
It is possible to prevent damage to the bearing due to these deformation force and strain force. Further, since the clip including the bearing and the cylindrical portion are bonded by the tapered surface, the bearing can be positioned concentrically with the cylindrical portion.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below based on the illustrated embodiments.

FIG. 1 is a sectional view showing a first embodiment of a spindle motor according to the present invention, and FIGS. 2 and 3 are a perspective view and a sectional view of a bracket and a bearing, respectively.

The bracket 2 fixed to the base 1 of the hard disk drive is composed of a collar portion 3 and a cylindrical portion 4 on the lower outer periphery. A pair of bearings 5, 6 are provided at the inner center of the cylindrical portion 4.
A step portion 7 for positioning the one bearing 5
Is fitted in the upper end of the cylindrical portion 4, and the other bearing 6 is fitted in the lower end of the cylindrical portion 4.

A plurality of axial slits 8 are radially formed at the upper end of the cylindrical portion 4 at equal intervals, and the outer ring of one bearing 5 is shrink fitted to the upper end of the cylindrical portion 4. It is fixed. The outer ring of the other bearing 6 is fixed to the lower end of the cylindrical portion 4 by press fitting, bonding, or a combination thereof.

Inside the cylindrical portion 4, a pair of bearings 5,
A shaft 9 is rotatably supported via 6. That is, the shaft 9 is inserted inside the inner races of both bearings 5 and 6, and these inner races are bonded and fixed to the shaft 9 by applying an appropriate preload.

A hub 10 made of aluminum or the like is fixed to the upper end of the shaft 9 so as to rotate together with the shaft 9. A magnetic disk (not shown) is mounted and mounted on the flange portion 11 of the hub 10 on the hub 10. A cylindrical iron yoke 12 is attached to the lower surface of the collar portion 11 of the hub 10 by shrink fitting, and a rotor magnet 13 is attached to the inner circumference of the yoke 12.

A stator 14 is fixed to the outer periphery of the cylindrical portion 4 of the bracket 2 so as to face the rotor magnet 13. Therefore, the stator 14 and the rotor magnet 13
The hub 10 rotates about the shaft 9 by the electromagnetic action between and, and the magnetic disk is rotated as required.

A cap 15 is disposed below the other bearing 6 so as to close the lower end opening of the cylindrical portion 4. This cap 15 can prevent dust from entering the hard disk. A labyrinth gap is formed over the entire circumference between the outer peripheral surface of the cylindrical portion 4 and the outer peripheral surface of the stator 14 and the lower and inner peripheral surfaces of the hub 10 and the inner peripheral surface of the rotor magnet 13. It has a sealing effect against grease splashing from and unclean air, and prevents these from entering the hard disk.

In the spindle motor having such a structure, when fixing one bearing 5 to the cylindrical portion 2, as shown in FIGS. 2 and 3, the inner periphery of the heated and expanded cylindrical portion 4 is attached. One bearing 5 is fitted. At this time, the height of one of the bearings 5 is regulated and positioned by the step portion 7 provided on the inner peripheral portion of the cylindrical portion 4. After heating, the cylindrical portion 4 gradually cools down and begins to contract, so that the fitted bearing 5 is firmly and surely fitted.

Although the outer ring of one of the bearings 5 may be damaged due to the heat shrinkage of the cylindrical portion 4 after the shrink fitting, the slit 8 formed at the distal end of the cylindrical portion 4 gives elasticity to this distal end. Therefore, the heat shrinkage force is absorbed, the outer ring of the one bearing 5 is not damaged, and stable rotation of the hub 10 is ensured. In the above-described embodiment, the case where one bearing 5 is shrink-fitted has been described, but one bearing 5 may be press-fitted and fixed to the tip portion of the cylindrical portion 4. In this case, the slit 8 can also be used to absorb damage to the outer ring of the one bearing 5 caused by press fitting.

FIG. 4 is a sectional view of a cylindrical portion 4 of a bracket 2 and one bearing 5 showing a second embodiment of a spindle motor according to the present invention.

In FIG. 4, a step portion 7 for defining the height of one of the bearings 5 is provided inside the tip portion of the cylindrical portion 4 of the bracket 2, and the step portion 7 is expanded from the step portion 7 toward the tip side. An annular tapered inner surface 16 is formed.

A clip 17 having the shape of a truncated cone that encloses one bearing 5 from the upper side is provided with a step portion 18 for engaging with the upper surface of the one bearing at the inner upper portion thereof, and the clip 1
7 is a taper outer surface 1 facing the taper inner surface 16
9 is formed. Furthermore, such a clip 17
A plurality of slits 20 in the axial direction are formed radially at equal intervals in a portion below the step portion 18 in.

When fixing the one bearing 5, first, the one bearing 5 is fitted into the clip 17 from the slit opening direction of the slit 20, that is, from below. At this time, since the one bearing 5 has elasticity imparted to the clip 17 itself by the slit 20, it is easily and surely fitted into the clip 17, and damage to the outer ring of the one bearing 5 caused by this press-fitting is also caused by this slit. It is a mechanism that uses 20 to absorb. The clip 17 including one bearing 5 is provided with a taper inner surface 16 of the cylindrical portion 4 to which an adhesive is applied.
The taper outer surfaces 19 are opposed to each other and bonded.

One of the bearings 5 is sandwiched between the step portion 7 on the side of the cylindrical portion 4 and the step portion 18 on the side of the clip 17, and its position is defined. Even when the adhesive applied to the adhesive surface between the inner taper surface 16 and the outer taper surface 19 is solidified and the clip 17 is deformed, this deformation force is absorbed by the slit 20 of the clip 17 and The outer ring of the bearing 5 is not damaged, one bearing 5 is not directly affected, and the shaft can be stably rotatably supported.

Although the embodiment of the spindle motor according to the present invention has been described above, the present invention is not limited to this embodiment, and various modifications can be made without departing from the scope of the present invention.

[0025]

Since the present invention is constructed as described above, it has the following effects. In the spindle motor according to claim 1, in the case of shrink fitting, the slit formed at the tip of the cylindrical portion of the bracket is caused by heat shrinkage that occurs after heating when the cylindrical portion and one bearing are fitted. Since the strain force is absorbed, the damage given to the outer ring of one of the bearings can be eliminated, and the roundness of the outer ring of one of the bearings can be kept constant without changing and fixed to the rotor or rotor. The recording disk can be rotated stably without shaking.

In the spindle motor according to the second aspect of the invention, the slit formed in the clip absorbs the strain force to the outer ring of one of the bearings due to uneven application of adhesive or the like, and damages the outer ring. As described above, the circularity of the outer ring of one bearing can be kept constant, and the interaction between the taper outer surface of the clip and the taper inner surface of the cylinder portion causes one bearing to be It becomes possible to install it accurately on the shaft center of, and the assembling accuracy can be improved.

[Brief description of drawings]

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

FIG. 2 is an exploded perspective view of a cylindrical portion and one bearing in FIG.

3 is a cross-sectional view of FIG.

FIG. 4 is a cross-sectional view showing a second embodiment of the spindle motor according to the present invention when one bearing is assembled.

5 is a cross-sectional view of a portion of FIG. 4 after assembly.

[Code number]

 2 Bracket 4 Cylindrical part 5 One bearing 6 The other bearing 7 Step part 8 Slit 9 Shaft 10 Hub 13 Rotor magnet 14 Stator 16 Taper inner surface 17 Clip 19 Taper outer surface 20 Slit

Claims (2)

[Claims] 1. A stator fixed to the outer periphery of a cylindrical portion of a bracket, a shaft rotatably supported inside the bracket via a pair of bearings, a rotor fixed to the shaft, and a rotor of the rotor. In a spindle motor provided with a rotor magnet arranged at a position facing the stator, a tip end portion of the cylindrical portion into which the one bearing is fitted,
A spindle motor, wherein a plurality of axial slits are radially formed, and the one bearing is shrink-fitted or press-fitted and fixed to a tip end portion of the cylindrical portion. 2. A stator fixed to the outer periphery of a cylindrical portion of a bracket, a shaft rotatably supported inside the bracket via a pair of bearings, a rotor fixed to the shaft, and a rotor of the rotor. In a spindle motor provided with a rotor magnet arranged at a position facing the stator, a height of one of the bearings is defined at an upper portion of an inner circumference of the cylindrical portion into which the one bearing is fitted. A stepped portion and an annular tapered inner surface that widens toward the tip side from the stepped portion are formed, and an annular tapered inner surface that encloses the one bearing and sandwiches the one bearing between the stepped portion and the stepped portion. A clip is provided, a plurality of axial slits are radially formed in the clip, and a taper outer surface facing the taper inner surface is formed on the outer circumference of the clip, and the taper outer surface is in contact with the taper inner surface. Spindle motor, characterized in that fixed.