JPH06284627A - Spindle motor - Google Patents

Abstract

PURPOSE:To provide a spindle motor in which distortion of ball bearing is absorbed to rotate a hub member smoothly and NRRO is reduced significantly to suppress vibration and noise. CONSTITUTION:The spindle motor comprises a hub member 3 for mounting a reproducing disc, a shaft 1, and a first ball bearing 2 interposed between the hub member 3 and the shaft 1, wherein the hub member 3 is rotary driven with respect to the shaft 1 and an annular groove 15 is made closely to the inner peripheral part of the hub member 3 press fitted with the first ball bearing 2 in order to absorb distortion thereof.

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 A conventional spindle motor for rotating a recording disk will be described with reference to FIG.
In FIG. 3, the illustrated spindle motor includes a shaft 1 which is a stationary member and a hub member 3 which is rotatable relative to the shaft 1.

The hub member 3 has a hat-shaped cross-section, and a magnet 5 is mounted on the inner peripheral surface of the hub member 3 with a yoke 4 interposed therebetween. The hub member 3 includes a base portion 3a and a base portion 3a.
It is composed of an extended portion 3b which is vertically provided on the outer periphery of the flange 3c, and a flange portion 3c which is provided at a lower end of the extended portion 3b. A plurality of magnetic disks are mounted on the upper side of the flange portion 3c. A first ball bearing 2 is interposed between the shaft 1 and the base 3a. A stator core 6 is arranged on the outer peripheral surface of the shaft 1 so as to face the magnet 5.
A coil 7 is wound around the stator core 6.

Inside the lower portion of the extension portion 3b of the hub member 3,
An annular bush 8 is mounted, and a second ball bearing 9 is interposed between the bush 8 and the shaft 1. The shaft 1 is provided with an insertion hole 10 through which a lead wire 13 for energizing the coil 7 is led out. And shaft 1
The magnetic fluid seal portions 11 are provided at the upper and lower ends of the.

[0005]

A ball bearing used in a spindle motor used in a magnetic disk device or the like has a dimensional error in the inner and outer rings and the ball itself due to a problem of machining accuracy. It is about 3-4 microns. When the roundness of the ball bearing is not 0, it appears as distortion of the ball bearing.
As a result, sufficient rotation accuracy cannot be obtained, and rotation fluctuation due to non-repetition, so-called NRRO (Non Repeat
There arises a problem that the active Run Out) becomes large. When this NRRO becomes large, the writing position and the reading position of the data on the recording medium are greatly different, which causes a problem such that erroneous data is read.
Further, the distortion of the ball bearing causes problems such as vibration and noise generation.

The present invention has been made in view of the above-mentioned problems existing in the prior art. The problem is to absorb the strain of the ball bearing and significantly reduce NRRO, An object of the present invention is to provide a spindle motor capable of suppressing vibration and noise.

[0007]

In order to achieve the above-mentioned object, in the spindle motor of the present invention, there is a strain absorbing member that opens axially outward in the vicinity of the inner peripheral portion of the hub member into which the ball bearing is press fitted. It has an annular groove.

The hub member is formed in a substantially hat shape having an open lower surface, the first ball bearing is interposed between the upper portion of the hub member and the stationary member, and the annular member is mounted inside the lower portion of the hub member. A second ball bearing is interposed between the bush and the stationary member, and annular grooves for strain absorption that are open outward in the axial direction are formed in the upper inner peripheral portion of the hub member and the inner peripheral portion of the bush, respectively. Is desirable.

In this case, the annular groove of the bush is formed wide, and the bracket or the base to which the stationary member is fixed is provided with an annular projection that is loosely inserted in the annular groove of the bush, and the inner surface of the annular groove and the annular projection are formed. A labyrinth gap may be formed between the outer surface and the outer surface of the portion.

Further, in the spindle motor of the present invention,
An annular groove for strain absorption, which opens inward and outward in the axial direction, is provided near the inner peripheral portion of the hub member into which the ball bearing is press fitted.

[0011]

In the above spindle motor, an annular groove for strain absorption is formed in the vicinity of the inner peripheral portion of the hub member into which the ball bearing is press fitted, and the wall thickness of this portion is made extremely thin, thereby The strain of the bearing is absorbed by the strain absorbing annular groove, NRRO can be significantly reduced, and vibration and noise can be suppressed.

Further, by forming an annular groove for absorbing strain, which is open to the outside in the axial direction, in the inner peripheral portion of the upper portion of the hub member and the inner peripheral portion of the annular bush mounted inside the lower portion of the hub member, respectively, It is possible to absorb the respective strains of the ball bearings at the same time, significantly reduce NRRO, and suppress vibration and noise.

Furthermore, the labyrinth seal can be constructed by utilizing the strain absorbing annular groove by loosely inserting the annular protrusion of the bracket or the base into the annular groove of the bush to form the labyrinth gap.

On the other hand, by forming an annular groove for strain absorption that opens inward and outward in the axial direction in the vicinity of the inner peripheral portion of the hub member into which the ball bearing is press-fitted, the strains at both edges of the ball bearing are simultaneously absorbed. can do.

[0015]

EXAMPLES Examples will be described with reference to FIGS. 1 and 2. The same reference numerals as those used above denote the same or corresponding ones.

FIG. 1 shows a first spindle motor of the present invention.
And shows a spindle motor for rotationally driving a magnetic disk, for example.

In FIG. 1, the illustrated spindle motor comprises a shaft 1 which is a stationary member and a hub member 3 which is rotatable relative to the shaft 1.
For the hub member 3, it is desirable to use a non-magnetic material such as aluminum that is easy to process. The hub member 3 has a hat-shaped cross section, and a magnet 5 is attached to the inner peripheral surface of the hub member 3 with a yoke 4 interposed therebetween. Hub member 3
Is a base portion 3a and an extension portion 3 vertically provided on the outer periphery of the base portion 3a.
b and a flange portion 3c provided at the lower end of the extension portion 3b, and a plurality of magnetic disks are mounted on the upper side of the flange portion 3c.

A first ball bearing 2 is interposed between the shaft 1 and the base 3a. An annular groove 15 for strain absorption, which opens upward, is formed in the vicinity of the inner peripheral portion of the base portion 3a into which the first ball bearing 2 is press fitted. In this case, although the strength of the hub member 3 is reduced by forming the annular groove 15 for absorbing strain, the strength of the hub member 3 is prevented from being greatly reduced by reducing the radial length of the annular groove 15. ing. A stator core 6 is arranged on the outer peripheral surface of the shaft 1 so as to face the magnet 5, and a coil 7 is wound around the stator core 6.

An annular bush 8 is mounted inside the extension 3b of the hub member 3, and a second ball bearing 9 is interposed between the bush 8 and the shaft 1. Shaft 1
An insertion hole 10 for leading out a lead wire 13 for energizing the coil 7 is provided in the. A magnetic fluid seal portion 11 is provided on the upper end of the shaft 1. In the vicinity of the inner peripheral portion of the bush 8 into which the second ball bearing 9 is press-fitted, a wide annular recess 8a that opens downward is formed.

A bracket 14 to which the shaft 1 is press-fitted and fixed
Is provided with an annular projection 14a that is loosely inserted into the annular recess 8a. The labyrinth gap 12 is formed by the upper surface of the bracket 14, the outer surface of the annular projection 14a, and the inner surface of the annular recess 8a. It prevents the lubricant from scattering to the outside. The labyrinth gap 12 also serves as an annular groove for strain absorption of the ball bearing. The bracket 14 may be a base.

Next, a second embodiment of the spindle motor according to the present invention will be described in detail with reference to FIG. The spindle motor of the second embodiment is also a spindle motor that rotationally drives a magnetic disk, as in the first embodiment already described.

In FIG. 2, in the vicinity of the inner peripheral portion of the base portion 3a of the hub 3 into which the first ball bearing 2 is press-fitted, an annular groove 16 for strain absorption opened upward and a strain absorption groove opened downward are provided. An annular groove 17 is provided, and the annular grooves 16 and 17 absorb the strain of the first ball bearing 2.

Generally, the stress of strain of a ball bearing is highest at the upper end and the lower end, and becomes smaller as it goes to the central portion, but the annular grooves 16 and 17 for strain absorption are provided at both the upper and lower portions of the base 3a. By providing, the stresses at both the upper end and the lower end of the first ball bearing 2 can be absorbed, and the strain can be absorbed more effectively than in the first embodiment.

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 and corrections 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, an annular groove for strain absorption is formed in the vicinity of the inner peripheral portion of the hub member into which the ball bearing is press fitted,
Since the wall thickness of this part is extremely thin, the strain of the ball bearing can be absorbed by the strain absorbing annular groove, stable rotation of the hub can be obtained, NRRO can be significantly reduced, and vibration and noise are generated. Can be suppressed.

According to a second aspect of the present invention, in the spindle motor for strain absorption, the upper inner peripheral portion of the hub member and the inner peripheral portion of the annular bush mounted inside the lower portion of the hub member are respectively opened to the outside in the axial direction. Since the annular groove is formed, the strains of the upper and lower ball bearings can be absorbed simultaneously, and more stable rotation of the hub can be obtained.

In the spindle motor according to the third aspect of the invention, since the labyrinth gap is formed by loosely inserting the annular projection of the bracket or the base into the annular groove of the bush, the labyrinth seal is utilized by utilizing the annular groove for strain absorption. Can be configured, a structure that combines strain absorption and sealing is obtained,
The structure is simple.

According to another aspect of the spindle motor of the present invention, the annular groove for strain absorption that opens inward and outward in the axial direction is formed in the vicinity of the inner peripheral portion of the hub member into which the ball bearing is press fitted. It is possible to absorb the strains at both edges of the bearing at the same time.

[Brief description of drawings]

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

FIG. 2 is a sectional view showing an essential part of a second embodiment of the spindle motor according to the present invention.

FIG. 3 is a cross-sectional view showing a conventional spindle motor.

[Explanation of symbols]

 1 Shaft 2 1st ball bearing 3 Hub member 8 Bushing 8a Annular recess 9 2nd ball bearing 12 Labyrinth gap 14 Bracket 14a Annular protrusion 15 Annular groove 16 Annular groove 17 Annular groove

Claims (4)

[Claims] 1. A hub member on which a recording disk is mounted,
A stationary member; and a ball bearing interposed between the hub member and the stationary member, wherein the hub member is a spindle motor that is rotationally driven relative to the stationary member, A spindle motor, wherein an annular groove for strain absorption that opens outward in the axial direction is provided in the vicinity of the inner peripheral portion of the hub member into which the ball bearing is press-fitted, and the strain of the ball bearing is absorbed. 2. The hub member is formed in a substantially hat shape having an open lower surface, a first ball bearing is interposed between an upper portion of the hub member and a stationary member, and the hub member is mounted inside a lower portion of the hub member. A second ball bearing is interposed between the annular bush and the stationary member, and a strain absorbing ring that is opened outward in the axial direction at the upper inner peripheral portion of the hub member and the inner peripheral portion of the bush. The spindle motor according to claim 1, wherein a groove is formed. 3. The annular groove of the bush is formed to be wide, and an annular protrusion that is loosely inserted in the annular groove of the bush is formed on a bracket or a base to which a stationary member is fixed, and an inner surface of the annular groove and the annular shape. The spindle motor according to claim 2, wherein a labyrinth gap that forms a labyrinth seal is formed between the outer surface of the protrusion and the labyrinth seal. 4. A hub member on which a recording disk is mounted,
A stationary member; and a ball bearing interposed between the hub member and the stationary member, wherein the hub member is a spindle motor that is rotationally driven relative to the stationary member, An annular groove for strain absorption that opens inward and outward in the axial direction is provided in the vicinity of the inner peripheral portion of the hub member into which the ball bearing is press-fitted, and the strain of the ball bearing is absorbed. Spindle motor.