JPS58184318A - Bearing unit - Google Patents

Abstract

PURPOSE:To enable application of pre-load without any deformation of a bearing by making a ring-like cage to encircle a bearing outer race and providing an engagement gap between the cage and a base. CONSTITUTION:A bearing 3b is forced into or bonded inside a ring-like cage 11 for settlement. The bearing is so designed that there is a fine gap between the cage 11 and a base 4 and an axial pre-load is applied to the cage 11, namely, the bearing outer race by a spring 7. The fine gap between the cage 11 and the base 4 is needed for application of the pre-load, however, it is not desirable that the gap is left after assembly from the view point of improvement of revolution accuracy. To dissipate the gap, a spring 8 axially pushes one point on the external periphery of the cage 11 via a metal fitting 15. The cage 11, at this time, may be formed in a shape to be held at three points 12-14.

Description

DETAILED DESCRIPTION OF THE INVENTION Object of the Invention The present invention relates to a bearing structure that improves the rotation accuracy of a spindle.

BACKGROUND OF THE INVENTION FIG. 1 shows an example of a spindle structure in a conventional disk drive device.

In FIG. 1, a plurality of magnetic disks 1 are fixed to a spindle hub 2. As shown in FIG. The spindle hub has 2 bearings (upper and lower) 3α+! It is rotatably attached to the base 4 via +h'&, and is rotationally driven around the shaft of the spindle hub by a drive motor composed of a motor magnet 5 and a motor winding 6. 1 between the inner and outer rings of bearings 3α and 5h to improve the rotational accuracy of the spindle.
It is necessary to remove the radial clearance. For this purpose, a minute clearance is provided between the outer ring of the bearing 3b and the base 4, and the spring 7 applies an axial preload to the outer ring of the υ bearing, resulting in the radial clearance of each bearing being reduced. removed. In order to prevent a decrease in rotation accuracy due to the clearance between the bearing outer ring and the base, a spring 8 presses a point on the outer ring of the bearing 3h in the radial direction to eliminate the clearance between the bearing outer ring and the base.

However, in this structure, the spring applies a radial force directly to the bearing outer ring in order to eliminate the gap between the bearing and the base, which tends to cause deformation of the bearing outer ring and reduce rotational accuracy. In addition, as shown in Figure 2, in the direction of the preload by the spring 8, the bearing and the base come into contact at two points 9 and 1°, leaving no gap, or there is a gap with no holding force in the direction perpendicular to the direction of the preload. This has the disadvantage that the spindle shaft tends to move easily, reducing rotational accuracy. Also, for the above reason, the bearing 5
Since the outer ring b is not positively fixed to the inner surface of the base 4, there is a possibility that the outer ring of the first bearing may also rotate during operation.

This causes a decrease in the rotation accuracy of the outer ring by 1 degree.

FIG. 3 shows an example of a spindle structure using a belt drive system. In this case, the motor is not directly installed on the hub 2, and the rotational force is applied to the belt 19. In the case of a belt-driven spindle structure, the operation is the same as in the previous example, except that the tension generated by the belt performs the same function as the spring 8 in the example shown in FIG.

OBJECTS OF THE INVENTION An object of the present invention is to eliminate the above-mentioned conventional problems, and to provide a preload without deforming the bearing;
Another object of the present invention is to provide a spindle structure that stably eliminates the gap between the fitting portion of the bearing and the base and enables highly accurate rotation.

A feature of the spindle structure of the present invention is that the outer ring of the bearing is surrounded by a ring-shaped retainer, and a fitting gap can be provided between the retainer and the base, making it possible to apply preload to the bearing. It is a matter of fact. In addition, a radial force is applied to the cage to remove the gap between it and the base, but the contact surface between the cage and the base is not a perfect circular surface. By forming the spindle into a shape such that the outer diameter surface is a curved surface that touches at three points, it is possible to obtain a spindle structure that has a stable holding force in all directions of the rotating shaft I.

Furthermore, a combination of concavities and convexities is provided on the fitting surface between the retainer and the base "Ij-" to serve as a rotation prevention mechanism for the outer ring of the bearing, and a spring for applying the preload to the retainer is guided so as to preload the retainer. 5. To prevent misalignment of the screws.

Next, embodiments of the present invention will be described in detail using the drawings. FIG. 4 is a sectional view of a spindle structure showing one embodiment of the present invention. Components with the same reference numerals indicate the same components as in the example of FIG. 1 above.

The bearing 3b is fixed by a ring-shaped retainer 11 or by adhesive. In this example it is a ball bearing. The structure 1 is such that a slight gap is provided between the cage 11 and the base 4, and an axial preload is applied to the cage, that is, the outer ring of the bearing, by the force of the spring 7. This axial preload causes the bearing 3α.

The radial clearance between the inner and outer rings of 5h is removed. Although this minute clearance between the retainer and the base is necessary to apply preload to the bearing, it is not desirable to leave it as is from the standpoint of improving rotational accuracy. Therefore, in order to absorb this gap, one place on the outer periphery of the cage was installed, and the bracket was
Although the bearing is pressed in the radial direction by the spring 8 via the bearing 5, the bearing is not pressed directly as in the conventional case, so there is little deformation of the bearing. Further, in this embodiment, FIG.

As shown in 4., the surface of the cage on the opposite side where the spring 8 acts is cut into a curved surface 16 having a radius of curvature slightly larger than the outer diameter of the cage. As a result, when a radial preload is applied by the spring 8, the retainer 12, 15
．． 14, and by the combined action of the forces acting at each point, it has a holding force against all external forces in the radial direction, including the direction of action of the spring 8, so it can be stably supported and has a high Accurate rotation can be achieved. Especially the fifth
In the figure, by setting the angle θ between the contact points 15 and 14 to 52 degrees with respect to the direction of action of the spring 80, a bearing support system having equal holding force in all radial directions can be constructed. Furthermore, for the reason mentioned above, the outer ring of the bearing 3b is not actively fixed to the base 4, so there is a possibility that it will rotate during operation.
There is. This rotation of the outer ring is also unfavorable in terms of improving rotation accuracy. For this purpose, a pin 17 is press-fitted into the retainer, and together with the retainer 15, constitutes a mechanism for preventing rotation of the outer ring of the bearing 3b. Further, the end face of the cage 11 is provided with a portion 19 covering the peripheral edge of the end face and seven flange 18 extending from the portion 19. The flange 18 has the function of defining the position of the spring 7 so that it does not shift in the radial direction, and the peripheral edge part 19 has the function of reinforcing the cage 11 against deformation in the radial direction. Even if the cage moves within the base due to impact or vibration, the spring 7 is guided so as not to hit the inner surface of the base 4, so that the cage returns to its original position with reproducibility.

FIG. 6 shows another embodiment of the invention. The difference from the above embodiment is that the outer diameter of the retainer 11 has a protrusion 19.2.
The only difference is that 0 is provided, and the rest is the same as the previous example.

With the configuration as described above, the following effects can be obtained in this embodiment.

1. By holding the outer ring of the bearing in a ring-shaped retainer and providing a fitting clearance between the retainer and the base, the preload can be maintained without deforming the bearing.
6゜11 2. By devising the shape of the outer diameter of the cage, the number of contact points between the base and the cage (i.e., the bearing outer ring) can be set to five, making it possible to create a stable bearing support structure.

3. The retainer and base can form a rotation prevention mechanism for the outer ring of the bearing.

4. Let the cage guide the preload spring,
By preventing contact between the preload spring and the base, even if the retainer moves, it can always be returned to a fixed position.

As described above, according to the present invention, a highly accurate bearing can be obtained.

[Brief explanation of drawings]

FIG. 1 is a vertical sectional view of the spindle structure of a conventional disk drive device, FIG. 2 is a sectional view taken along line A-A in FIG. 1, and FIG.
The figure is a vertical cross-sectional view of another conventional structure, FIG. 4 is a vertical cross-sectional view showing one embodiment of the present invention, FIG. Other embodiments of T0 are shown below. 1... Magnetic disk, 2... Spindle hub,
3α, 3h...Bearing, 4...Base 5...
・Motor magnet. 7・6...Motor winding, 7...Spring, 8...Spring, 9,1o...Contact point. 11...Cage, 12,15.14...Contact point. 15... Bracket, 16... Different diameter curved surface, 17
...Pin 18...Pulley, 19...
·belt. Representative Patent Attorney Susuki 1) Toshiyuki 8 ・ ) → Ihenyaku ΣΣ2 92 42 4b

Claims (1)

[Claims] 1. A bearing, a bearing holding member having a cylindrical portion that holds the peripheral surface of the bearing, a base member that holds the outer periphery of the bearing holding member, and a radial direction of the bearing holding member. a pressurizing means for applying pressure in one direction, and the outer periphery of the bearing holding member is shaped so as to contact the base member at a plurality of points outside the direction of the pressurization. Device. 2. The bearing device according to claim 1, wherein the bearing holding member and the pressing means have uneven portions that prevent rotation of the bearing holding member by engaging with each other. .