JP2000002258A - Bearing unit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide the subject unit capable of restraining swinging of a rotation shaft and reducing an axial size. SOLUTION: This unit bearing 10 is provided with an inner bearing 14 and an outer bearing 15. An inner race 14 of the inner rearing 14 is directly fixed to a rotational shaft 100. An inner race inner diameter of an outer bearing 20 is made larger than an outer diameter of an outer race of the inner bearing 14. The outer bearings 20 is arranged outer than the inner bearing 14 in the radial direction so that both the bearings 14, 20 may be overlapped with each other in a radial plane. The inner race 21 of the outer bearing 20 is fixed to the rotational shaft 100 via a support member 12.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a bearing unit having a plurality of bearings, and more particularly, to a bearing unit that can be mounted on a spindle or the like of a disk drive.

[0002]

2. Description of the Related Art Conventionally, for example, a bearing unit is attached to a spindle or the like of a floppy disk drive. Japanese Unexamined Utility Model Publication No. 63-103018 discloses a bearing unit as shown in FIG.

[0003] As shown in FIG. 5, a bearing unit 80 comprises:
2 axially arranged in the cylindrical portion 82 of the housing 81
The rolling ball bearings 84 are provided. A collar 85 is fitted between the two bearings 84. A protrusion 8 having a circular hole 87 is provided on the outer peripheral edge of the flange portion 83 of the housing 81.
6 are formed at equal intervals in the circumferential direction. A circular hole 88 is also formed on the flange portion 83. A mandrel 89 is buried inside the flange portion, and screw holes 90 and 91 are provided in the mandrel 89 at positions corresponding to the circular holes 87 of the protrusions and the circular holes 88 on the flange portion, respectively. .

If the above-described bearing unit 80 is mounted on a rotating shaft (not shown), the rotating shaft can be supported at two locations in the axial direction by two bearings 84. Deflection of the rotating shaft can be suppressed.

[0005]

In the bearing unit 80 described above, since the bearings 84 are arranged in series in the axial direction in the housing 81, the dimensions in the axial direction are large, and the bearings 84 are mounted on a spindle or the like of a disk drive. In such a case, there is a problem that the apparatus becomes large. In addition, it is conceivable to arrange a rolling bearing and a sliding bearing in series in the housing in the axial direction. However, even in such a case, the axial dimension is large, and when two rolling bearings are used. This is not preferable because the deflection of the rotating shaft becomes large as compared with the above. Furthermore, it is conceivable to dispose only one bearing in the housing. However, in such a case, although the axial dimension is small, the run-out of the rotating shaft is considerably large, which is not preferable. An object of the present invention is to solve the above-described problems, and to provide a bearing unit that can suppress the run-out of a rotating shaft and has a small axial dimension.

[0006]

The object of the present invention is to provide a bearing unit having a plurality of bearings for supporting the same rotating shaft and a housing for supporting each outer ring of the plurality of bearings. At least one pair of the bearings is configured such that the inner diameter of the inner ring of one bearing is larger than the outer diameter of the outer ring of the other bearing, and the two bearings overlap in the radial plane, so that the one bearing is the other of the other bearings. This is achieved by a bearing unit which is disposed radially outward of the bearing, and wherein the inner ring of the one bearing is supported by a support member fixed to the rotating shaft.

[0007] Here, the degree of overlap between the one bearing and the other bearing is not particularly limited. For example, when the bearing width of one bearing is substantially equal to that of the other bearing, they overlap over half or more of the bearing width. Is preferred. Further, an outer diameter surface of the one bearing may be further provided with another bearing whose inner diameter surface overlaps. In this case, an inner ring of the another bearing is also supported by a support member fixed to a rotating shaft. Is done.

[0008] The support member is not particularly limited, but is preferably a member capable of applying a preload to the bearing to be supported.
A metal member formed in an appropriate shape, a resin member, or the like can be employed. The fixing of the support member to the rotating shaft may be performed by press fitting or may be performed via another member.

According to the bearing unit configured as described above, one of the bearings is arranged radially outward of the other bearing so that at least a pair of bearings overlap in the radial plane. The axial dimension of the bearing unit can be reduced. Further, since the rotating shaft can be supported at two points in the axial direction by the inner ring of the other bearing and the supporting member fixed to the inner ring of the one bearing, it is possible to suppress the run-out due to the rotation of the rotating shaft. Can be.

[0010]

Embodiments of the present invention will be described below in detail with reference to the drawings. The unit bearing 10 according to the first embodiment shown in FIG. 1 includes an inner bearing 14 and an outer bearing 20. The inner ring 15 of the inner bearing 14 is
It is directly fixed to the rotating shaft 100. And outer bearing 2
0 is disposed such that the inner diameter surface 21a of the inner ring 21 of the bearing is axially overlapped with the outer diameter surface 16a of the outer ring 16 of the inner bearing in the radial direction surface. 12 and is fixed to the rotating shaft 100.

Outer ring 16 of inner bearing 14 and outer bearing 20
Are supported by the resin housing 11, respectively. The housing 11 is engaged with an upper surface and an outer diameter surface 16a of the outer race 16 of the inner bearing 14 in the drawing, and has a cross section L
It has an L-shaped inner locking portion 11a and an L-shaped cross-section outer locking portion 11b that engages the lower surface and the outer diameter surface of the outer ring 22 of the outer bearing 20 in the drawing. Further, the support member 12 includes a locking portion 12a which engages with the upper surface and the inner diameter surface 21a of the inner race 21 of the outer bearing 20 in the drawing.

The outer bearing 20 includes an outer locking portion 11b and a supporting member 12 of the housing 11 in which the inner locking portion 11a is engaged with the inner bearing 14 and movement of the housing 11 is restricted in a downward direction in the drawing.
And the locking portion 12a.

FIG. 2 shows a state in which the above-described first embodiment is attached to a motor for driving a floppy disk.
The bearing unit 10 is mounted on a rotating shaft 31 of the motor 30. At the tip of the support member 12 of the bearing unit 10, a bottomed cylindrical rotor case 32 having a rotor magnet 33 fixed to the inner peripheral surface is fixed. The drive coil 3 is provided at the tip of the housing 11 of the bearing unit 10.
5 is fixedly secured to the stator 34. The fixing of the rotor case 32 to the support member 12 and the fixing of the stator 34 to the housing 11 can be performed by conventional screw fastening or the like.

The bearing unit 10 as described above is
Outer diameter surface 16a of inner bearing 14 and inner diameter surface 2 of outer bearing 20
1a is arranged so as to overlap in the radial plane, so that the dimension in the axial direction is small. Therefore, by attaching the motor to a floppy disk drive motor or the like, the size of the motor or the like can be reduced. Also, the inner ring 1 of the inner bearing
5 and the supporting member 12 fixed to the inner ring 21 of the outer bearing, the rotating shafts 100 and 31 can be supported at two positions in the axial direction, so that the rotating shafts such as a motor for driving a floppy disk can be rotated. The accompanying axial runout (NRRO) of the floppy disk can be suppressed.

FIG. 3 shows a second embodiment of the present invention. In the bearing unit 40 of the present embodiment, the outer bearing 50
Of the rotating shaft 1 via a metal supporting member 42.
00. The support member 42 has a support portion 42a formed by bending the tip of the support member. Further, on the outer peripheral edge of the support member 42, preload portions 42b which contact the upper surface of the inner ring 51 of the outer bearing in the drawing and apply a preload to the bearing are formed at regular intervals in the circumferential direction.

To assemble the bearing unit 40,
First, while fixing the inner bearing 44 to the rotating shaft 100,
The housing 41 is attached to the inner bearing. Next, the outer bearing to which the support member 42 is attached is mounted on the housing 41. Finally, the fixing member 43 is attached to the rotating shaft 100 by press fitting, and the supporting member 42 is pressed down in the figure. At this time, the preload portion 42b applies a preload to the outer bearing 50.

In the bearing unit 40 configured as described above, since the support member 42 having the preload portion 42b is fixed to the rotating shaft 100 by the fixing member 43, the degree of press-fitting of the fixing member 43 is adjusted. , Preload part 42b
Thus, the preload applied to the outer bearing 50 can be adjusted. After the support member 42 is loosely fitted to the rotation shaft 100, the support member 42 is
, The assembling property is good.

FIG. 4 shows a third embodiment of the present invention. The third embodiment has a configuration in which the shape of the support member 42 in the second embodiment is changed and the fixing member 43 is omitted, and the other configuration is the same as that of the second embodiment. This bearing unit 60
Is provided with a press-fit portion 62c on the inner peripheral edge so that the support member 62 can be fixed to the rotary shaft 100 by press-fit.
According to such a bearing unit 60, the number of parts can be reduced, and the cost can be reduced.

The bearing unit of the present invention is not limited to the above-described embodiment, but can be appropriately modified and improved. For example, in the above-described embodiment, a ball bearing whose rolling element is a ball is described as a rolling bearing. However, the present invention is not limited to a ball bearing, and may be another rolling bearing such as a roller bearing. Further, it may be an angular bearing. Further, a configuration in which three or more bearings overlap in the radial plane may be employed.

[0020]

As described above, in the bearing unit of the present invention, one of the bearings is disposed radially outward of the other so that at least a pair of bearings overlap in the radial plane. The inner race of one bearing is supported by a support member fixed to the rotating shaft. Therefore, it is possible to reliably suppress the deflection of the rotating shaft and to obtain a bearing unit having a small axial dimension.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a first embodiment of the present invention.

FIG. 2 is a diagram in which the first embodiment is attached to a motor of a disk drive device.

FIG. 3 is a diagram showing a second actual machine mode of the present invention.

FIG. 4 is a diagram showing a third actual machine mode of the present invention.

FIG. 5 is a view showing a conventional bearing unit.

[Explanation of symbols]

 Reference Signs List 10 bearing unit 11 housing 12 support member 14 inner bearing (other bearing) 16a outer diameter surface 20 outer bearing (one bearing) 21a inner diameter surface

Claims (1)

[Claims] 1. A plurality of bearings for supporting the same rotating shaft,
In a bearing unit comprising a housing that supports each outer ring of the plurality of bearings, at least one pair of the plurality of bearings is configured such that an inner ring inner diameter of one bearing is larger than an outer ring outer diameter of the other bearing, One bearing is disposed radially outward of the other so that the two bearings overlap in the radial plane, and the inner ring of the one bearing is supported by a support member fixed to the rotating shaft. A bearing unit characterized in that: