JP3201862B2 - 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 rotor hub which is rotatably supported on a fixed shaft via a rolling bearing, and a space between the fixed shaft and a rotating portion such as a rotor hub is sealed by an annular seal member. A spindle motor.

[0002]

2. Description of the Related Art A rotor hub b is rotatably supported on a fixed shaft c via a ball bearing a, and an annular seal is provided between the fixed shaft c and a rotating portion such as the rotor hub b. As a spindle motor that seals with a member, it is common practice to use a combination of a rotary seal member d and a fixed seal member e having complicated shapes as shown in FIG.

[0003] However, when a rotary seal member d and a fixed seal member e having such complicated shapes are used in combination, there are many complications in making and assembling the seal member. Only the rotary seal member f is fitted and fixed to the inner peripheral surface b1 of the rotor hub b, and the gap between the rotary seal member f and the fixed shaft body c is set smaller.

In this case, however, the concentricity between the inner peripheral surface of the inner race a1 externally fitted to the fixed shaft body c of the ball bearing a and the outer peripheral surface of the outer race a2 to which the inner peripheral surface b1 of the rotor hub b is externally fitted, In addition to the concentricity of the outer peripheral surface f1 of the rotary seal member f, which is fitted inside the inner peripheral surface b1 of the rotor hub b, and the inner peripheral surface f2 facing the outer peripheral surface of the fixed shaft body c, the inner peripheral surface of the rotor hub b b1
Of the rotor hub b and the outer peripheral surface f1 of the rotary seal member f are not made to have a remarkable loose fit or tight fit. Otherwise, the gap between the rotary seal member f and the fixed shaft member c cannot be set with high accuracy by accurately aligning the rotary seal member f with the fixed shaft member c. It was an obstacle.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems in the prior art, and has as its object to align a seal member with a fixed shaft body and to improve the alignment of the seal member. An object of the present invention is to provide a spindle motor capable of accurately and efficiently setting a radial gap between a circumference and an outer peripheral surface of a fixed shaft body.

[0006]

In order to achieve the above object, a spindle motor according to the present invention is arranged such that a rotor hub is connected to a fixed shaft by means of a pair of rolling bearings whose inner ring is externally fitted to the fixed shaft. A spindle motor rotatably supported, comprising at least one of the rolling bearings
The outer ring of the outer ring
A part of the annular portion of the inner peripheral surface of the
In the other annular portion of the outer peripheral surface of the outer ring, a small-diameter portion and a large-diameter
The large-diameter inner peripheral surface of an annular seal member having a peripheral surface is externally fitted.
Fixed , concentricity between the inner peripheral surface of the inner ring and the outer peripheral surface of the outer ring of the rolling bearing, and the large-diameter inner peripheral surface of the seal member
The concentricity with the inner circumference of the small inner diameter is sufficiently small,
The small inner diameter portion of the seal member is opposed to the outer peripheral surface of the fixed shaft via a slight radial gap.

[0007]

The concentricity between the inner peripheral surface of the inner ring of the rolling bearing and the outer peripheral surface of the outer ring, and the large-diameter inner peripheral surface fitted to the outer peripheral surface of the outer ring of the annular seal member and the outer peripheral surface of the fixed shaft body The concentricity with the inner circumference of the small inner diameter portion facing each other is sufficiently small .
Therefore, the rotor hub is fixed via a pair of rolling bearings.
It is rotatably supported on the fixed shaft body, and has a small number of rolling bearings.
At least one annular part that forms part of the outer peripheral surface of the outer ring
Externally fix a part of the inner circumference of the rotor hub
And a small inner diameter on the other annular portion of the outer peripheral surface of the outer ring.
Part of the annular seal member having a portion and a large-diameter inner peripheral surface.
By externally fixing the peripheral surface , the seal member can be accurately aligned with the fixed shaft body, and the radial gap between the small inner diameter portion of the seal member and the outer peripheral surface of the fixed shaft body can be precisely formed. Can be set.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a sectional view of a hard disk drive spindle motor as one embodiment of the present invention. Needless to say, the spindle motor of the present invention can be used for driving various recording media other than a hard disk.

The bracket 10 is provided with an annular recess 1 having an upper opening.
0a has a cylindrical portion 10b protruding up and down on the inner peripheral side, and has a flange portion 10c on the outer peripheral side of the annular concave portion 10a. The bracket can be formed integrally with the base of the hard disk drive, for example.

An inner peripheral lower portion of the stator core 12 is externally fitted and fixed to an outer peripheral portion of an upper end of the cylindrical portion 10b of the bracket 10. The stator core 12 includes a stator coil 1
4 is wound.

The lower portion of a substantially cylindrical fixed shaft 16 is press-fitted and fixed to the cylindrical portion 10b. A screw hole 18 is provided in the upper part of the hollow part of the fixed shaft body 16, and a rubber ball 20 for sealing is fitted in the lower part. An adhesive holding groove 22 for holding an adhesive for fixing a ball bearing is provided on the entire outer circumference at two locations on the upper portion of the fixed shaft body 16.

The rotor hub 24 made of an iron-based material has a double cylindrical shape with a bottom. The inner periphery of the inner peripheral wall 24a is rotated on the outer periphery of the fixed shaft body 16 via upper and lower ball bearings 26 and 28. It is freely supported. The spacer portion 24b protruding on the inner peripheral side of the inner peripheral wall 24a is sandwiched between outer rings 26a and 28a of the upper and lower ball bearings 26 and 28. This place
Of the outer ring 26a of the upper ball bearing 26 on the lower side.
The annular portion has a space in the inner peripheral wall 24a of the rotor hub 24.
The annular inner peripheral surface adjacent to the upper side of the
Have been.

[0013] A bottom 24 located above the rotor hub 24
In (c), a hard disk (not shown) fitted to the outer peripheral wall 24d of the rotor hub 24 is used for fixing a clamper (not shown) for clamping the hard disk between the upper surface of the flange portion 24e and the hard disk. A screw hole 30 is provided. Screw hole 30
Is closed by a sealing member 32 adhered to the lower surface of the bottom portion 24c. Inner peripheral surface 24 of bottom 24c
c1 is slightly larger in diameter than the inner peripheral wall 24a. The inner upper corner of the bottom 24c is a chamfered inclined surface 24c2.
Is formed.

The flange portion 24e projects outwardly from the lower end of the outer peripheral wall 24d of the rotor hub 24, and approximately half its axial direction is inserted into the annular recess 10a.

The rotor magnet 34 has a cylindrical shape and is fixed and held on the inner peripheral portion of the outer peripheral wall 24d of the rotor hub 24.
The stator core 12 and the rotor magnet 34 face inward and outward with a radial gap therebetween. A spacer 3 is provided between the sealing member 32 and the upper end of the rotor magnet 34.
6 are interposed.

The annular seal member 38 includes a horizontal portion 38a.
And a hanging portion 38b located below the outer peripheral portion thereof,
The upper outer corner of the horizontal portion 38a is a chamfered inclined surface 38a.
1 is formed.

The concentricity between the inner peripheral surface of the inner ring 26b of the upper ball bearing 26 and the outer peripheral surface of the outer ring 26a, and the concentricity between the inner peripheral surface of the hanging portion 38b of the seal member and the inner peripheral surface of the horizontal portion 38a. ,
The outer ring 26a of the upper ball bearing 26 is sufficiently small.
And the clearance between the inner peripheral surface of the hanging portion 38b of the seal member 38 and the inner peripheral surface of the sealing member 38 are accurately processed so as to be sufficiently small, and the upper ring of the outer peripheral surface of the outer ring 26a is formed.
The inner peripheral surface of the depending portion 38b of the sealing member 38 in Jo portion (large diameter
The inner peripheral surface is externally fitted and fixed. And the sealing member 38
The inner peripheral surface of the horizontal portion 38a is opposed to the outer peripheral surface of the fixed shaft body 16 via a slight radial gap. Also, at least a portion of the fixed shaft body 16 where the inner ring 26b of the upper ball bearing 26 is fitted to the outside and a portion of the outer peripheral surface of the portion facing the inner peripheral surface of the horizontal portion 38a of the seal member 38 have sufficient roundness. It is processed with high precision to be small. The outer diameter of the hanging portion 38 b is equal to the inner peripheral surface 2 at the bottom 24 c of the rotor hub 24.
It is slightly smaller than the inner diameter of 4c1.

The inclined surface 3 of the horizontal portion 38a of the seal member 38
8a1 and the inclined surface 24c2 of the bottom 24c of the rotor hub are provided with the adhesive 40, so that the sealing member 38 is provided.
And the rotor hub 24 are sealed and fixed to each other. The angle between the two inclined surfaces 38a1 and 24c2 is set to an obtuse angle because the seal member 38 and the rotor hub 2
This is because the adhesive 40 can be prevented from peeling off as much as possible when there is a difference between the two due to the difference in the coefficient of thermal expansion of the adhesive.

The concentricity between the inner peripheral surface of the inner ring 26b of the upper ball bearing 26 and the outer peripheral surface of the outer ring 26a, and the concentricity between the inner peripheral surface of the hanging portion 38b of the seal member 38 and the inner peripheral surface of the horizontal portion 38a. Are sufficiently small, and the outer ring 2 of the upper ball bearing 26
Since the gap between the outer peripheral surface of the outer ring 26a and the inner peripheral surface of the hanging portion 38b of the sealing member 38 is accurately processed so as to be sufficiently small, the hanging portion 38 is formed on the outer peripheral surface of the outer ring 26a.
The outer peripheral surface of the upper and lower ball bearings 26
The seal member 38 for the fixed shaft body 16 without machining the inner circumferential surface of the inner circumferential wall 24a of the rotor hub 24 and the inner circumferential surface 24c1 of the bottom portion 24c of the rotor hub 24 to be fitted on the outer circumferential surfaces of the outer races 26a. And a radial gap (for example, about 25 μm) between the horizontal portion 38a of the seal member 38 and the outer peripheral surface of the fixed shaft body 16 is uniformly and accurately set over the entire circumference. can do. Therefore, it is possible to easily enhance the sealing effect, effectively prevent the lubricant and the like of the upper ball bearing 26 from leaking outward, and avoid the contamination of the hard disk and the like.

A lower end of the inner peripheral wall 24a of the rotor hub 24 and an outer upper end of the cylindrical portion 10b of the bracket 10;
The lower ball bearing 28 is lubricated by the outer peripheral surface of the inner peripheral wall 24a, the inner peripheral surface of the stator core 12, the lower surface and the outer peripheral surface of the flanged portion 24e of the rotor hub 24, the bottom surface of the annular recess 10a of the bracket 10, and the inner peripheral surface of the outer wall. It exhibits a labyrinth seal-like effect of preventing agents and the like from scattering to the outside of the spindle motor.

FIG. 2 is a sectional view of a spindle motor for driving a hard disk as another embodiment of the present invention.

A stator core 52 is externally fitted and fixed at a vertically intermediate position of a substantially cylindrical fixed shaft body 50, and a stator coil 53 is wound around the stator core 52. An inner ring 54a of a lower ball bearing 54 is externally fitted and fixed to the lower portion of the fixed shaft body 50, and an inner ring 56a of an upper ball bearing 56 is externally fitted and fixed to the upper portion.

A substantially bowl-shaped rotor hub 58 having an opening at the center of the base 58a is rotatably supported on the fixed shaft body 50 via upper and lower ball bearings 56 and 54. An inner peripheral portion of a lower end of a peripheral wall 58b of the rotor hub 58 is supported on an outer peripheral side of an outer ring 54b of the lower ball bearing 54 via an annular member 60 fitted therein, and an inner peripheral portion of a base portion 58a of the rotor hub 58 has an upper ball bearing. 56 on the lower annular portion of the outer peripheral surface of the outer ring 56b.
It is externally fixed and supported. A rotor yoke 64 in which a rotor magnet 62 is internally fitted and fixed is fixed on an inner peripheral side of a peripheral wall 58b of the rotor hub 58, and the rotor magnet 62 faces the stator core 52 with a radial gap therebetween. A hard disk 66 externally fitted to the rotor hub 58 is provided on a base 58a of the rotor hub 58 by a peripheral wall 58b.
There is provided a screw hole 68 for fixing a clamper 67 for holding the pressure between the flange 58c and the lower portion 58c. A spacer 69 is interposed between the inner peripheral portions of the hard disk 66. Lead wire 53 from stator coil 53
“a” is drawn out below the fixed shaft body 50 through a drawing hole 70 that communicates the inside of the motor with the lower end surface of the fixed shaft body 50.

The upper portion of the inner peripheral portion of the base portion 58a of the rotor hub 58 is slightly enlarged in diameter, and the upper corner of the inner peripheral portion is formed as a cutout portion 58a1 having a substantially J-shaped cross section. In addition, the annular member 6
The lower portion of the inner peripheral portion of the O is slightly enlarged in diameter, and the lower corner of the inner peripheral portion is formed in a cutout portion 60a having a substantially J-shaped cross section.

The annular upper seal member 72 includes a horizontal portion 72a.
And a hanging portion 72b located below the outer peripheral portion thereof,
The upper outer corner of the horizontal portion 72a is formed as a cutout 72a1 having a substantially J-shaped cross section.

The degree of concentricity between the inner peripheral surface of the inner ring 56a of the upper ball bearing 56 and the outer peripheral surface of the outer ring 56b, and the concentricity between the inner peripheral surface of the hanging portion 72b of the upper seal member 72 and the inner peripheral surface of the horizontal portion 72a. The degree is sufficiently small so that the gap or interference between the outer peripheral surface of the outer ring 56b of the upper ball bearing 56 and the inner peripheral surface of the hanging portion 72b of the upper seal member 72 is sufficiently small. Of the outer ring 56b.
The inner peripheral surface (large-diameter inner peripheral surface) of the hanging portion 72b of the upper seal member 72 is externally fitted and fixed to the annular portion on the side of the upper part . The inner peripheral surface of the horizontal portion 72a of the upper seal member 72 is
With a slight radial gap. A portion of the fixed shaft body 50 in which at least the inner ring 56 a of the upper ball bearing 56 is externally fitted;
The outer peripheral surface of the portion facing the inner peripheral surface of the horizontal portion 72a is also accurately processed so that its roundness is sufficiently small. The outer diameter of the hanging portion 72b is equal to the base 58 of the rotor hub 58.
a is slightly smaller than the inner diameter of the inner peripheral upper part slightly enlarged.

An adhesive 74 is provided in a generally U-shaped recess formed by the notch 72a1 of the upper seal member 72 and the notch 58a1 of the base 58a of the rotor hub 58.
Thus, the upper seal member 72 and the base 58 of the rotor hub 58
a and the two are fixed. Since the intersection angle between the two notches 72a1 and 58a1 is obtuse, the adhesive 74 can be separated as much as possible when a difference occurs between the upper seal member 72 and the rotor hub 58 due to a difference in the coefficient of thermal expansion. Can be prevented.

The concentricity between the inner peripheral surface of the inner ring 56a of the upper ball bearing 56 and the outer peripheral surface of the outer ring 56b, and the concentricity between the inner peripheral surface of the hanging portion 72b of the upper seal member 72 and the inner peripheral surface of the horizontal portion 72a. The degree is sufficiently small so that the gap or interference between the outer peripheral surface of the outer ring 56b of the upper ball bearing 56 and the inner peripheral surface of the hanging portion 72b of the upper seal member 72 is sufficiently small. Since the inner peripheral surface of the hanging portion 72b is externally fixed to the outer peripheral surface of the outer ring 56b, the upper ball bearing 5
6, the inner peripheral surface of the base 58a of the rotor hub 58, which is externally fitted to the outer peripheral surface of the outer ring 56b and is located on the outer peripheral side of the hanging portion 72b, is not machined with high precision so that its roundness is sufficiently small. The center of the upper seal member 72 with respect to the fixed shaft body 50 can be accurately aligned, and the radial gap between the horizontal portion 72a of the upper seal member 72 and the outer peripheral surface of the fixed shaft body 50 extends over the entire circumference. Can be set evenly and accurately. Therefore, it is possible to easily enhance the sealing effect, effectively prevent the lubricant or the like of the upper ball bearing 56 from leaking outside, and avoid the contamination of the hard disk or the like.

The annular lower seal member 76, annular member 60, and adhesive 78 have the same configuration as the upper seal member 72, the base 58a of the rotor hub 58, and the adhesive 74, and perform the same operations.

The vertical positional relationship in the description of each embodiment described above is merely for convenience of description based on the drawings, and does not limit the actual use state and the like.

[0031]

According to the spindle motor of the present invention, unlike the prior art, the sealing member for the fixed shaft body is independent of the processing accuracy of the inner peripheral surface of the rotor hub or the like fitted to the outer peripheral surface of the outer ring of the rolling bearing. Can be accurately performed, and the radial gap between the small inner diameter portion of the seal member and the outer peripheral surface of the fixed shaft body can be accurately set, so that the manufacturing process can be simplified while enhancing the sealing effect. It is very effective in increasing manufacturing efficiency.

[Brief description of the drawings]

FIG. 1 is a sectional view of a spindle motor for driving a hard disk.

FIG. 2 is a cross-sectional view of another hard disk drive spindle motor.

FIG. 3 is a sectional view of a main part of a conventional spindle motor.

FIG. 4 is a sectional view of a main part of a conventional spindle motor.

[Description of sign]

 16 Fixed shaft body 26 Upper ball bearing 26a Outer ring 26b Inner ring 38 Seal member 38a Horizontal portion 38b Hanging portion 50 Fixed shaft body 56 Upper ball bearing 56a Inner ring 56b Outer ring 72 Upper seal member 72a Horizontal portion 72b Hanging portion 76 Lower seal member

Continuation of the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) H02K 5/10 H02K 5/173

Claims (1)

(57) [Claims] An inner ring is externally fixed to a fixed shaft body.Pair ofThis
The rotor hub rotates with respect to the fixed shaft via a rolling bearing.
A spindle motor rotatably supported,Outer ring outer periphery on at least one of the rolling bearings
A part of the inner peripheral surface of the rotor hub is
The annular portion is fitted and fixed to the outside, and the outer peripheral surface of the outer ring is
An annular part with a small inner diameter part and a large diameter inner peripheral surface on the other annular part
The large-diameter inner peripheral surface of the seal member is externally fitted and fixed,  Concentricity between the inner peripheral surface of the inner ring and the outer peripheral surface of the outer ring of the rolling bearing
Degrees andA large-diameter inner peripheral surface and a small-diameter portion of the seal member
The concentricity with the inner periphery of each is sufficiently small, and the small inner diameter portion of the seal member is
It is characterized by being opposed via a slight radial gap
Spindle motor.