JPH0355178Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a spindle motor, and particularly to a spindle motor for a disk.

[Conventional technology and its problems]

Conventional spindle motors have different coefficients of thermal expansion due to differences in the materials of their component parts, resulting in dimensional differences during use, resulting in deviations in the theoretical center of rotation. The shaft collapsed. As a result, bearings may be damaged, rotational vibration may occur, and in particular, an off-track phenomenon of the magnetic disk may occur. In particular, conventional spindle motors that have these problems cannot be used as spindle motors for recent high-density magnetic disks.

[Means for solving problems]

The present invention forms a concave groove in a part of the motor shaft, fits an elastic member such as a leaf spring into the groove, and connects the inner ring of the bearing to the groove into which the elastic member is fitted. It was fitted externally to close it.

[Effect]

When distortion occurs due to thermal expansion differences in the mating parts, etc., the elastic member in the groove elastically presses the inner ring of the bearing in a fixed direction, so the motor shaft does not swing. It only falls in a certain direction. If the direction of this fall is set in a direction where off-track is less likely to occur, the off-track phenomenon can be prevented. Furthermore, since the inner ring of the bearing is always elastically pressed against the motor shaft in a fixed direction, damage to the bearing, vibration, and noise can be prevented.

〔Example〕

The illustrated embodiment will be described in detail below.

In FIG. 6, reference numeral 1 denotes a bracket, and a pair of bearings 3 and 4 are fitted and held on the inner circumferential surface of a cylindrical boss portion 2 of the bracket, and a motor shaft 5 is centered through both bearings 3 and 4. It is rotatably supported. In addition, 6 is a stator and is fixed to the outer peripheral surface of the cylindrical boss part 2. A hub 7 is fixed to one end of the motor shaft 5, and a magnetic recording disk 8 is mounted on this hub 7. The hub 7 is approximately in the shape of an inverted spatula, and a magnetic shielding material 9 is fitted inside the hub 7, and a permanent magnet 10 is fitted inside the hub 7.

As shown in FIGS. 6, 7, and 8, one of the bearings 3 has an inner ring elastic pressing mechanism W that elastically presses the inner ring in a predetermined radial direction B at all times. attached.

That is, in FIGS. 6 to 8 and FIGS. 1 to 4, a recessed groove 11 is formed in a part of the motor shaft 5, and a resilient member having a leaf spring portion 12 in this recessed groove 11 is shown. 13
At the same time, insert the inner ring 3a of the bearing 3.
is externally fitted so as to close the groove 11 into which the elastic member 13 is fitted.

To explain more specifically, the resilient member 13 is
It is composed of a substantially arc-shaped ring main body part 14 with a partially cut out part, and a leaf spring part 12 with a part of the center thereof standing up in the shape of an "E" shape. The concave groove 11 of the motor shaft 5 is easily formed by cutting by machining, but the small diameter portion 15 is formed by cutting out a flat portion 16 in a part as shown in FIGS. 4 and 8. A corresponding flat portion 14a is also formed on the other ring main body portion 14. This prevents the resilient member 13 from rotating.

As shown by the imaginary line in FIG. 1, the outermost diameter end of the leaf spring portion 12 protrudes beyond the outer circumferential surface of the motor shaft 5 in the free state, but when the bearing 3 is fitted onto the outside, the outermost end of the leaf spring portion 12 protrudes beyond the outer peripheral surface of the motor shaft 5, as shown by the solid line. The inner ring 3 is elastically deformed in the inner diameter direction.
A is constantly pressed elastically in the radial direction B.

As shown in FIG. 5, two parallel surfaces 17, 17 are formed on the small diameter portion 15, and
It is also preferable that the open ends of the ring main body 14 are formed into two parallel pieces 18, 18 and crimped onto the two surfaces 17, 17 to prevent rotation.

In addition, in FIG. 6, the inner ring and outer ring of the upper bearing 4 are fixed to the motor shaft 5 and the cylindrical boss part 2, respectively, but the lower bearing 3 has only the outer ring 3b fixed to the cylindrical boss part 2. The inner ring 3a is loosely fitted onto the motor shaft 5 in a movable state (race), and is configured such that the springing force of the inner ring springing and pressing mechanism W in the direction of arrow B acts effectively.

In FIGS. 7 and 8, the angle β formed between the radial direction B on which the above-mentioned elastic biasing force acts, that is, the arrangement position of the leaf spring portion 12, and the movement direction A of the magnetic head 19. is preferably set at approximately 90°.
In other words, an internal stress absorption radial direction B in which internal stress due to thermal expansion is absorbed by the inner ring elasticity pressing mechanism W;
A phase difference of approximately 90° is provided between the magnetic head 19 and the moving direction A of the magnetic head 19.

The reason for this is that as the temperature changes, relative thermal strain occurs between each component, and internal stress is generated in each component. Strain and stress are absorbed in a concentrated manner, and the axial center of the motor shaft 5 is slightly tilted in the radial direction B. However, even if such a tilting of the shaft occurs, the amount of off-track due to the relative positional deviation in the radial direction between the track drawn on the disk 8 and the magnetic head 19 that reads it is minimized at β.
In the case of ≒90°.

Next, FIG. 9 shows another embodiment in which a fixed motor shaft 5 is erected on a bracket 1, a bearing 4 at a lower position with both inner and outer rings fixed, and an inner ring 3.
Only the outer ring 3a is movable (loose) in the axial direction, and the outer ring 3b is fixed to the inner circumferential surface of the hub 7. 7 is rotatably supported. 20 is a preload elastic member such as a disc spring;
Only the inner ring 3a is resiliently biased downward in the figure. The stator 6 is fixed to the fixed motor shaft 5, and the permanent magnet is fixed to the hub 7 at an intermediate position between the upper and lower sides.

Therefore, the motor shaft 5 is connected to the upper loose inner ring 3.
A concave groove 11 is provided at the fitting position with a, and the resilient member 13 as described above is fitted into this to constitute the inner ring resilient pressing mechanism W. In this case as well, as shown in FIG.
and the direction of motion A of the magnetic head 19, the angle β
Set to approximately 90°.

Next, as shown in FIGS. 10 and 12, no notch is formed in the ring body portion 14 of the resilient member 13,
It is also preferable to extend a part of the upper end edge upward and then bend it downward, so that the letter-shaped plate spring portion 12 has a long dimension. Further, the concave groove 11 is composed of a circumferential groove and a rotation stopper notch 21 which is partially cut out in the axial direction, and the extension part 22 is engaged with the notch 21 as shown in FIG. do.

Furthermore, as shown in FIG.
It is also preferable to have two or more sheets. In addition, in FIG. 10 or FIG. 11, it is also possible to use means other than those shown in FIG. 12 to prevent rotation, for example, the groove 1
1 is a circumferential groove, and a flat portion 16 and two surfaces 17, 17 as shown in the cross section of FIG. 4 or 5 are cut out in a part.

Note that the present invention can be freely applied to spindle motors of various shapes and structures other than the illustrated embodiment, and the resilient member 13 may be the concave groove 11 of the motor shaft 5.
Leaf springs of other shapes, as long as they can be fitted into
It is free to use coil springs, rubber or plastic blocks, and other various materials.

[Effect of idea]

The present invention has the following significant practical effects due to the above-described configuration.

It can prevent off-track phenomenon and realize high-density rotation.

In particular, thermal strain caused by temperature changes can be effectively absorbed by the resilient member 13.

This prevents damage to the bearing 3 and extends its life.

In terms of manufacturing, the shaft is easy to process, the groove 11 can be easily formed, and the cost is low.

Minute vibrations generated by the motor are effectively absorbed, resulting in quiet rotation, and the volume of the conventional motor can be maintained as is.

[Brief explanation of the drawing]

Fig. 1 is an enlarged partial sectional view of the main parts showing an embodiment of the present invention, Fig. 2 is a perspective view of the main parts, Fig. 3 is a perspective view of the main parts, and Fig. 4 is a sectional plan view of the main parts. FIG. 5 is a cross-sectional plan view of the main part of the modified example, FIG. 6 is a front cross-sectional view of the whole, FIG. 7 is a perspective view explaining the operation, FIG. 8 is a cross-sectional plan view, and FIG. 9 is a cross-sectional plan view of another embodiment. Cross-sectional view shown, 1st
FIG. 0 and FIG. 11 are perspective views showing a modification example replacing FIG. 2, and FIG. 12 is an enlarged partial sectional view of the main part. 3... Bearing, 3a... Inner ring, 5... Motor shaft, 11... Concave groove, 13... Resilient member.

Claims (1)

[Scope of utility model registration request] A groove 11 is formed in a part of the motor shaft 5, and a resilient member 13 such as a leaf spring is fitted into the groove 11.
A spindle motor characterized in that an inner ring 3a of a bearing 3 is fitted onto the outside so as to close the groove 11 into which the resilient member 13 is fitted.