JPH04244755A - Bearing structure and spindle motor - Google Patents

Abstract

PURPOSE:To reduce in size a bearing section, to simplify its assembly and to improve its rotating accuracy. CONSTITUTION:A first member 11, a second member 12, and spheres 2, 3 are provided. The member 11 has annular grooves 5, 7 on the outer periphery 4 and an axially orthogonal end face 6. The member 12 has a vessel shape for enclosing the member 11. Annular grooves 13, 15 are provided on the inner peripheral surface 10 of the cylindrical wall of the member 12 and the inner side flat surface 14 of a bottom wall 9. One spheres 2,... are rotatably interposed between the groove 5 of the periphery 4 of the member 11 and the groove 13 of the surface 10 of the member 12. The other spheres 3,... are rotatably interposed between the groove 7 of the end face 6 of the member 11 and the groove 15 of the surface 14 of the 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 structure and a spindle motor using the same.

0002

2. Description of the Related Art Conventionally, in spindle motors for rotationally driving magnetic disks, optical disks, etc., a structure in which two or three sets of radial ball bearings are arranged side by side along a shaft has been widely used.

0003

[Problems to be Solved by the Invention] Recently, there has been a demand for this type of OA equipment to be made thinner, as exemplified by the thinner (more compact) size of laptop personal computers and the like.

However, the above-mentioned ball bearings consist of a cylindrical inner ring, an outer ring, and a ball (sphere) inserted between them, and in order to maintain its rigidity, durability, etc. It is difficult to do so, and there is also the problem that when two (or three) sets of such ball bearings are installed side by side along the shaft as described above, the axial dimension will inevitably increase. .

The present invention solves these problems and achieves compactness (thinness) while maintaining the rigidity and durability necessary to prevent the rotation axis from wobbling and suppress the generation of vibration and noise. The purpose is to

[0006]

[Means for Solving the Problems] The present invention includes a spherical body, a first member having an annular groove in which the spherical body rolls formed in an outer peripheral surface and an end face perpendicular to the axis, and a first member that surrounds the first member. This bearing structure includes a second member in which an annular groove in which the sphere is arranged and in which the sphere rolls is recessed in the inner circumferential surface and a plane perpendicular to the axis.

Further, the spindle motor of the present invention has such a bearing structure, and further includes the first member and the second member.
One of the members is fixed to the rotor or forms part of the rotor, and the other is fixed to the bracket or forms part of the bracket.

[0008]

[Operation] The annular groove on the outer circumferential surface of the first member and the annular groove on the inner circumferential surface of the second member face each other, and a plurality of spheres are fitted in a rotatable manner between the annular grooves.

[0009] Furthermore, the end face perpendicular to the axis of the first member and the end face perpendicular to the axis of the second member are opposed to each other, and the annular grooves formed therein are opposite to each other, and a plurality of annular grooves are formed between the two annular grooves. The spheres are fitted in such a way that they can roll freely.

[0010] In this way, the radial and axial positions of the first member and the second member that rotate relative to each other around their axes are regulated, and the rotation side of the first member and the second member is regulated. Regulates the runout (vibration) of the shaft center.

Furthermore, since only one row of annular grooves and one row of spheres rolling in the annular grooves are disposed on the opposing circumferential surfaces of the first member and the second member, the axial dimension is extremely small. It's over.

Further, since an annular groove and a group of spheres rolling in the groove are arranged on the opposing end faces and the plane perpendicular to the axis of the first member and the second member, the thrust force can be reliably applied. I can receive it.

[0013] Therefore, the first member and the second member, or
The bracket and rotor of a spindle motor using this technology reliably suppresses wobbling of the axis of rotation during coaxial relative rotation, making it possible to reduce vibration and noise while achieving a compact and thin design.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be explained in detail below based on the illustrated embodiments.

FIGS. 1 and 2 show different embodiments of a spindle motor having a bearing structure 1 of the present invention, and illustrate a radial gap type motor for driving a magnetic disk.

In FIG. 1 or 2, the bearing structure 1 includes a first member 11 as a rotating shaft, a second member 12 in the shape of a cylinder with a bottom surrounding the first member 11, and a space between them. It is equipped with interposed spheres 2, 3, and so on.

The first member 11 has a solid short cylindrical shape, and has one annular groove 5 recessed in the outer circumferential surface 4 and an axially perpendicular end surface 6 formed perpendicular to the axial center C. Another annular groove 7 is recessed therein.

Each of the annular grooves 5 and 7 has an arcuate cross-sectional shape, and each of the annular grooves 5 and 7 is arranged in a circle centered on the axis C.

The second member 12 consists of a cylindrical wall portion 8 and a bottom wall portion 9.

The inner circumferential surface 10 of the cylindrical wall portion 8 faces the outer circumferential surface 4 of the first member 11 with a small gap therebetween, and one annular groove 13 is recessed in the inner circumferential surface 10 .

This annular groove 13 and the annular groove 5 face each other, and a group of spheres 2 are rotatably interposed between them.

Furthermore, an annular groove 15 is concentrically formed in a plane 14 perpendicular to the axis corresponding to the inner surface of the bottom wall portion 9 .

The axially perpendicular plane 14 and the axially perpendicular end surface 6 of the first member 11 face each other with a small gap, and
The annular groove 15 and the annular groove 7 face each other.

Another group of spheres 3 are interposed between the annular grooves 15 and 7 in a freely rolling manner.

[0025] In cross-section, each of the annular grooves 13 and 15 has an arcuate shape, and is in a circular shape centered on the axis C.

Therefore, in the embodiment shown in FIG.
The contact angle of the sphere 3 and the contact angle of the sphere 3 are in the same direction, and the load direction line E of the sphere 2 and the load direction line G of the sphere 3 are both inclined toward the bottom wall 9 side with respect to the axis C. intersects with.

Moreover, as is clear from FIG. 1, between the groups of spheres 2 and 3, the component forces of the vectors in the direction parallel to the axis C are the same in magnitude but in opposite directions. A preload is applied to the

That is, the first member 11 receives a component of force in the downward direction in the figure from the group of spheres 2, and receives a component of force in the upward direction in the figure by the group of spheres 3. There is.

Of course, in the radial direction, the sphere 2...
Balanced within the group, and balanced within the other sphere 3...group. However, the first member 11 receives a radially inward component of force from the former, and receives a radially outward component of force from the latter.

Next, in the embodiment shown in FIG. 2, the contact angle of the sphere 2 and the contact angle of the sphere 3 are in different directions.

However, as in FIG. 1, the load direction line E of the sphere 2 and the load direction line G of the sphere 3 both intersect obliquely with respect to the axis C.

Also, in FIG. 2, the assembly is performed with preload applied, and there is a gap between the spheres 2 and 3 groups.
It is also the same as the previous embodiment in that a preload is applied so that the component force of the vector in the direction parallel to the axis C has the same magnitude but the direction is opposite.

However, in FIG. 2, the first member 11 receives a radially inward component force from both the spheres 2 and 3.

Next, a spindle motor using the bearing structure 1 shown in FIG. 1 or 2 will be explained.

Reference numeral 16 denotes a rotor, which is in the shape of an inverted shallow cap, and is fixed to the first member 11 serving as a rotating shaft.

That is, the small protrusion 18 of the first member 11 is inserted into the hole 17 of the boss portion at the center of the rotor 16 and fixedly connected.

An outer flange 19 is provided on the outer peripheral surface of the rotor 16 to receive a magnetic disk (not shown). A rotor magnet 20 has a ring shape or a segment shape corresponding to a predetermined number of magnetic poles, and is fixed to the inner peripheral surface of the rotor 16.

A case in which the first member 11 is fixed to the rotor 16 in this manner is shown.

On the other hand, 21 is a bracket flange portion, into which the second member 12 is inserted and fixed.

That is, the second member 12 and the bracket flange portion 21 constitute a bracket 23. In other words, in FIG. 1 or 2, the second member 12 is
This example shows a case in which it forms part of the

A stator 24 is fixed to the outer peripheral surface of the cylindrical wall portion 8 of the second member 12, which is a part of the bracket 23, and is disposed opposite to the rotor magnet 20.

Next, in another embodiment shown in FIG. 3, the structure of the bearing structure 1 is the same as that shown in FIG. The difference is that the member 11 is used on the stationary side and the second member 12 is used on the rotating side.

To explain in more detail, in FIG. 3, the small protrusion 18 of the first member 11 is inserted into the hole 22 of the bracket 23.
The bracket 23 is inserted into the bracket 23 and fixed thereto, and is erected on this bracket 23 as a fixed shaft of the motor. In this way, the first member 11 is fixed to the bracket 23.

On the other hand, the second member 12 forms a part of the rotor 16. That is, the rotor 16 has a rotor main body 28 consisting of an inner cylindrical portion 25, a flat wall portion 26, and an outer cylindrical portion 27.
and a second member 12 inserted and fixed into the hole 25a of the inner cylindrical portion 25.

The rotor magnet 20 has this inner cylindrical portion 25.
is fixed to the outer circumferential surface of the

[0046] The bracket 23 has a shaft concentrically with the axis C.
A cylindrical wall portion 29 is provided upright and faces the inner circumferential surface of the outer cylindrical portion 27 of the rotor 16 with a small gap therebetween.

A stator 24 is fixed to the inner surface of this cylindrical wall portion 29, and the inner circumferential surface of the stator 24 and the rotor magnet 20 are arranged to face each other.

Next, FIG. 4 shows a method of assembling the bearing structure 1.

First, in step (2), the spheres 3 are placed in the annular groove 15 of the bottom wall portion 9 of the second member 12.

In the next step (2), the first member 11 is replaced with the second member 1.
Insert it into 2.

In the subsequent step (2), the second member 12 is partially heated to deform it so that the opening side of the cylindrical wall portion 8 is expanded in diameter as shown by the imaginary line, and the spheres 2 are inserted. It is inserted between the annular grooves 5 and 13.

[0052] When the temperature of the second member 12, which has been raised once by the heating described above, decreases, a preload is automatically applied.

That is, as is clear from the above-mentioned FIG. 1 or FIG. 2, the positions of the annular grooves 7 and 15 and the annular grooves 5 and 13 are slightly shifted from each other. Axial and radial preload acts between the first member 11 and the second member 12 via the spheres 3 .

Note that in FIGS. 1 to 4, the illustration of a retainer similar to a normal ball bearing is omitted, but if desired, the spheres 2... group and the sphere 3 group... Used to maintain even distribution.

Further, in the illustrated embodiment described above, the illustration of a seal device/seal member for preventing lubricant from scattering is omitted, but it is preferable to use a labyrinth seal, a magnetic fluid seal, etc. as appropriate.

It should be noted that the present invention is applicable to designs other than the above-described embodiments. For example, the present invention can be applied to a spindle motor having a disk clamp section for an optical disk (magneto-optical disk) or a rotary bearing for other motors. The bearing structure of the present invention can be freely applied to any part.

Furthermore, in terms of the structure of the spindle motor, in addition to the radial gap type shown in the drawings, an axial gap type is also desirable (as it allows for further reduction in thickness).

Furthermore, the first member 11 serving as the shaft may be made hollow.

Furthermore, in FIG. 1 or 2, the first member 1
1 and the rotor 16 are integrally formed, or the second member 12
It may also be preferable to form the bracket flange portion 21 and the bracket flange portion 21 in one piece.

In FIG. 3, the first member 11 and the bracket 2
3 as an integral part, or the second member 12 and the rotor body 28
It is equally preferable to combine the two into one.

1 or 3, the hole 30 at the center of the bottom wall 9 allows the second member 12 to be inserted into the hole 22 of the bracket flange 21 (in the case of FIG. 1) or the rotor body 28. It is used when press-fitting into the hole 25a (in the case of FIG. 3).

That is, a small protrusion of a pressing jig (not shown), which is formed by forming a small protrusion with a small diameter with a stepped portion at the tip of a rod, is inserted into the hole 30 to release the second member 12. Press the center of the bottom wall portion 9 to press fit it into the holes 22, 25a.

[0063] As a result, the axis of the second member 12 is pressed, force is applied evenly, and damage to the bearing due to uneven pressure fitting can be prevented.

[0064] After that, the hole 30 is covered with a sealing member 31 to prevent the scattering of grease and the like.

Note that this hole 30 can also be omitted.

[0066]

Effects of the Invention The bearing structure of the present invention can securely hold the first member 11 and the second member 12 so as to be relatively rotatable around the axis C, and the bearing structure between the outer circumferential surface 4 and the inner circumferential surface 10 can be A group of spheres 2 and a sphere 3 between the end face 6 perpendicular to the axis and the plane perpendicular to the axis 14.
The group reliably restricts the wobbling of the rotation axis C in both the radial and axial directions, thereby significantly reducing vibration and noise.

Furthermore, the bearing structure of the present invention (without the inner and outer rings of conventional ball bearings) can be made thinner and more compact, and has excellent durability and rigidity. Moreover, it is easy to assemble.

The spindle motor of the present invention can be made thinner and more compact as a whole, and
It is possible to realize highly accurate rotation without causing vibration or the like of the rotation axis C, and with little vibration or noise.

Furthermore, if the bearing structure 1 is assembled into a unit in advance and then assembled into other parts such as the rotor 16 and the bracket 23 to form a spindle motor, assembly becomes easier.

[Brief explanation of the drawing]

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

FIG. 2 is a sectional view of another embodiment.

FIG. 3 is a cross-sectional view of another embodiment.

FIG. 4 is an explanatory diagram of an assembly method.

[Explanation of symbols]

1 Bearing structure 2 Sphere 3 Sphere 4 Outer peripheral surface 5 Annular groove 6 End face perpendicular to the axis 7 Annular groove 10 Inner peripheral surface 11 First member 12 Second member 13 Annular groove 14 Axis orthogonal plane 15 Annular groove 16 Rotor 23 Bracket C Axis center

Claims (2)

[Claims] 1. A first member 11 having spheres 2 and 3, annular grooves 5 and 7 in which the spheres 2 and 3 roll, which are recessed in an outer peripheral surface 4 and an end surface 6 perpendicular to the axis; an annular groove 13, 1 which is arranged to surround 11 and in which the spheres 2, 3 roll;
5 is recessed in the inner circumferential surface 10 and the plane perpendicular to the axis 14.
A bearing structure comprising a member 12. 2. A first member 11 having spheres 2 and 3, annular grooves 5 and 7 in which the spheres 2 and 3 roll, which are recessed in an outer peripheral surface 4 and an end surface 6 perpendicular to the axis; an annular groove 13, 1 which is arranged to surround 11 and in which the spheres 2, 3 roll;
5 is recessed in the inner circumferential surface 10 and the plane perpendicular to the axis 14.
The bearing structure has a bearing structure composed of the member 12, and further, one of the first member 11 and the second member 12 is fixed to the rotor 16 or forms a part of the rotor 16,
A spindle motor characterized in that the other end is fixed to a bracket 23 or forms a part of the bracket 23.