JPH104665A - Spindle motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To effectively prevent the thermal deformation of a hub main body, caused by a temperature rise in a disk-mount section by providing projections on the hub main body and/or a yoke for producing a clearance between the hub main body and yoke. SOLUTION: An annular positioning projection 68 which protrudes downward is provided on the internal surface of the inner flange 66 of a yoke 40, and magnets 42 are mounted on the yoke 40, so that their upper surfaces can come into contact with the front end face of the projection 68. In addition, a projection 70 which is protrudes appreciably downward is provided on the lower surface of a disk-mount section 60. The projection 70 has a rectangular cross section and is formed into an annular state at the corner between the section 60 and an attaching projection 62. Because of the projection 70, an appreciable clearance 72 is formed between the lower surface of the section 60 and the upper surface of the inner flange 66 of the yoke 40. Therefore, even when a thermal stress is generated between the section 60 and flange 66, owing to a temperature rise in a motor, the stress is absorbed by the elastic deformation of the projection 70, and the thermal deformation of a hub main body can be prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a spindle motor for rotating a recording disk such as a magnetic disk.

[0002]

2. Description of the Related Art For example, a spindle motor for rotating a recording disk generally includes a bracket mounted on a base of a drive, a hub rotatable relative to the bracket, and a magnet mounted on the hub. And a stator disposed to face the magnet. The hub has a hub body to which a recording disk is attached,
A yoke to which a magnet is attached is provided, and the yoke is disposed below the hub body.

The connection between the hub body and the yoke is, for example, shown in FIG.
Is performed as shown in FIG. A disk mounting portion 4 on which a recording disk is mounted is provided at a lower portion of the hub main body 2, and a mounting projection 6 protruding downward is provided at a lower surface of the disk mounting portion 4. The yoke 8 has a cylindrical yoke main body 10 and an inner flange 12 projecting inward from an upper end of the yoke main body 10. The yoke 8 has an inner flange 12
The free end of the protruding projection 6 protruding from the inner flange 12 is positioned such that the upper surface of the protruding projection abuts against the lower surface of the disk mounting portion 12 and the inner peripheral surface of the inner flange 12 abuts the outer peripheral surface of the mounting projection 6. The portion is caulked to be mounted below the hub body 2.

[0004]

However, in this type of spindle motor, the hub body 2 and the yoke 8 are not provided.
In connection with the above-described combination, there are the following problems to be solved. That is, usually, the hub body 2 is formed from aluminum, and the yoke 8 is formed from iron.
When the temperature of the drive device equipped with the motor rises, the hub body 2 and the yoke 8 thermally expand, and the contact surface between them, that is, the lower surface of the disk mounting portion 4 and the inner flange 12 of the yoke 8.
Thermal stress is generated between the upper surface and the upper surface, and when the thermal stress increases, thermal deformation occurs in both. At this time, the hub body 2 made of aluminum is relatively easily deformed, so that the disk mounting portion 4 is particularly thermally deformed, and distortion occurs on the upper surface of the disk mounting portion 4. As a result, the recording surface of the recording disk placed on the disk
, The information recorded on the recording disk cannot be read accurately.

An object of the present invention is to provide a spindle motor capable of effectively preventing thermal deformation accompanying a rise in the temperature of a disk mounting portion of a hub body.

[0006]

SUMMARY OF THE INVENTION The present invention comprises a bracket, a hub rotatable relative to the bracket, a magnet mounted on the hub, and a stator disposed opposite the magnet. The hub includes a hub body on which a recording disk is mounted and a yoke on which a magnet is mounted, and a disk mounting portion on which the recording disk is mounted is provided at a lower portion of the hub main body, and is provided below the disk mounting portion. A spindle motor having a yoke mounted thereon, wherein the hub body and / or the yoke are provided with projections for creating a gap between the two. According to the present invention, since a projection for forming a gap is provided between the hub body and the yoke, even if a thermal stress occurs between the hub body and the yoke due to a temperature change, the thermal stress is absorbed by the elastic deformation of the projection. In addition, free thermal expansion is allowed in the gap between the two, and as a result, thermal deformation of the hub body, particularly the disk mounting portion, is prevented.

According to the present invention, the yoke has a cylindrical yoke main body and an inner flange projecting radially inward from an upper end of the yoke main body. The protrusion is provided on the hub main body, and is provided on an upper surface of the inner flange. It is characterized by contact. According to the present invention, since the projection is provided on the hub body, the projection is easily elastically deformed, and the thermal deformation of the disk mounting portion can be effectively prevented.

Further, the present invention is characterized in that the projection is provided annularly on the lower surface of the disk mounting portion and abuts on the inner peripheral edge of the inner flange of the yoke. According to the present invention, since the projection is annular, it can be easily formed, and acts on the inner peripheral edge of the inner flange of the yoke, so that thermal deformation of the disk mounting portion can be more effectively prevented. it can.

[0009]

FIG. 1 is a sectional view showing an embodiment of a spindle motor according to the present invention. In FIG. 1, a spindle motor of the illustrated form includes a bracket 22 and a hub 2 which is rotatable relative to the bracket 22.
4 is provided. The bracket 22 has a circular bottom wall 26.
A side wall 28 extending upward from an outer peripheral edge of the bottom wall 26;
It has a flange 30 extending radially outward from the upper end of the side wall 28, and the flange 30 is fixed to a base (not shown) of the disk drive by, for example, a fixing screw (not shown). A shaft member 32 is fixed to the bottom wall 22 of the bracket 22, and a tip end thereof extends substantially vertically upward from the bottom wall 26. The hub 24 is rotatably supported by the shaft member 32 via a pair of bearings 34 and 36 which are arranged at intervals in the vertical direction. Hub 24
Is composed of a hub body 38 and a yoke 40 mounted on the hub body 38. The configurations of the hub body 38 and the yoke 40 will be described later in detail.

A ring-shaped magnet 42 is mounted on the inner peripheral surface of the yoke 40. A stator 44 is disposed facing the magnet 42. The stator 44
A stator core is formed by stacking a plurality of core plates, and the stator core is mounted on an outer peripheral surface of an annular wall protruding from the bottom wall of the bracket. A coil 50 is wound around the stator core 46 as required. Therefore, the coil 50
, A magnetic interaction occurs between the stator 44 and the magnet 42, which causes the hub 24 to rotate in a predetermined direction.

A magnetic fluid sealing means 52 is provided outside one of the bearings 34, and a cap member 54 is further provided outside the sealing means 52. The sealing means 52 and the cap member 54 are attached to the hub body. 38. A labyrinth member 56 is provided outside the other bearing 36. The magnetic fluid sealing means 52 and the labyrinth member 56 prevent grease particles used for the bearings 34 and 36 from scattering outside. Further, the cap member 54 prevents the magnetic fluid of the magnetic fluid sealing means 52 from scattering to the outside.

Next, the hub body 38 and the yoke 40 will be described with reference to FIG. 2 together with FIG. At the lower portion of the hub body 38, a disk mounting portion 60 protruding outward in the radial direction is integrally provided. The recording disk (not shown) is attached to the hub body 38, and the lowermost recording disk is mounted on the upper surface of the disk mounting portion 60. The hub body 38 is formed from aluminum or an aluminum alloy. On the lower surface of the disk mounting portion 60,
An annular mounting projection 62 projecting downward is provided integrally,
The disk mounting portion 60 and the mounting protrusion 62 define a corner that opens to the lower right in FIG.

The yoke 40 is formed of iron, for example, and has a cylindrical yoke main body 64 and an inner flange 66 protruding inward from the upper end of the yoke main body 64. The yoke 40 has an upper surface of the inner flange 66 and the disk mounting portion 6.
0 is located at the corner so that the inner peripheral surface of the inner flange 66 is in contact with the outer peripheral surface of the mounting projection 62 and the free end protruding from the inner flange 66 of the protruding projection 62. The peripheral portion is caulked to be plastically deformed, so that it is attached below the hub body 38, that is, below the disk mounting portion 60.

The inner surface of the inner flange 66 of the yoke 40 (FIG. 2)
(A lower surface in FIG. 2) is provided with an annular positioning projection 68 protruding downward, and the magnet 42 is mounted on the yoke 40 such that the upper surface of the magnet 42 comes into contact with the distal end surface of the projection 68.

In the embodiment, the lower surface of the disk mounting portion 60 is provided with a projection 70 projecting somewhat downward.
The projection 70 has a substantially rectangular cross section and is provided in an annular shape at the corners of the disk mounting portion 60 and the mounting projection 62. The lower surface of the disk mounting portion 60 and the yoke 40 A slight gap 72 is created between the inner flange 66 and the upper surface. It is desirable that the width of the projection 70 in the radial direction is small so that it is somewhat elastically deformed as described later.

In the spindle motor having such a configuration, since the projection 70 is provided on the lower surface of the disk mounting portion 60, the distortion absorption between the lower surface of the disk mounting portion 60 and the upper surface of the inner flange 66 of the yoke 40. There is a gap 72 for Therefore, even if the temperature of the motor rises and a thermal stress is generated between the two, the thermal stress is absorbed by the elastic deformation of the projection 70, and the portion above the inner flange 66 of the yoke 40 The lower surface of the disk mounting portion 60 and the upper surface of the inner flange 66 of the yoke 40 are not substantially pressed against each other except for the portion where the projection 70 exists. As a result, substantially no thermal stress is generated in the disk mounting portion 60 of the hub body 38, and thermal deformation thereof is prevented.

In the embodiment, the protrusions are provided annularly on the lower surface of the disk mounting portion 60. Instead of providing the protrusions annularly, for example, a plurality of hemispherical protrusions are provided at intervals in the circumferential direction. It may be. In addition, the disc mounting unit 6
Instead of or along with the lower surface of
A projection may be provided on the upper surface of the inner flange 66 of the yoke 40. Note that the projection 70 is preferably provided on the hub body 38 rather than the yoke 40 so that the projection 70 is easily elastically deformed. Further, the projection 70 can be provided on the lower surface of the disc mounting portion 60 so as to act on an arbitrary portion such as the inner peripheral edge portion (embodiment) of the inner flange 66, the outer peripheral edge portion, or an intermediate portion thereof. It is preferable that the thermal stress acts on the inner peripheral edge of the inner flange 66 as shown in FIG. 2 so that the thermal stress acts on the projection 70 in the axial direction.

FIG. 3 shows another embodiment of the spindle motor of the present invention. In this embodiment, the structure of the hub and the location of the protrusions are changed,
The other structure is substantially the same as the embodiment shown in FIGS. In order to facilitate understanding, the same members as those shown in FIGS. 1 and 2 will be described with the same reference numerals.

In FIG. 3, in the illustrated spindle motor, the hub body 80 includes a disk mounting portion 82 and a support sleeve portion 84. Support sleeve part 84
Is formed from a material such as iron, for example, while the disc mounting portion 82 can be formed from aluminum or an aluminum alloy. The inside diameter of both ends of the support sleeve portion 84 is larger than the inside diameter of the middle portion, and the large inside diameter portions 86 and 88 are rotatably supported by the shaft member 32 via bearings 34 and 36, respectively. Further, annular concave portions 90 and 92 are provided on the outer peripheral surfaces of both ends of the support sleeve portion 84. In the embodiment, annular concave portions 90 and 92 are provided inside the large inner diameter portions 86 and 88. Such an annular recess 9
Reference numerals 0 and 92 denote intermediate portions of the support sleeve portion 84 (the annular concave portions 9).
0, 92) due to thermal deformation of the bearing 34,
Desirably, the width and depth are such that they are not substantially transmitted to 36. The outer diameter of the intermediate portion of the support sleeve portion 84 is set slightly larger than the outer diameters of both end portions thereof, and the intermediate portion is connected to the inner peripheral surface of the disc mounting portion 82 by, for example, shrink fitting. . Such hub body 8
At 0, when a relatively large thermal stress is generated at the joining portion between the disc mounting portion 82 and the intermediate portion of the support sleeve portion 84 due to the temperature rise, the portion defining the concave portions 90 and 92 of the support sleeve portion 84 due to the thermal stress. Is somewhat elastically deformed (elastic deformation is allowed by the presence of the concave portions 90 and 92), and thermal stress is absorbed by the elastic deformation. In addition, the presence of the concave portions 90 and 92 allows thermal deformation of the intermediate portion 84 in the axial direction. Therefore, a large thermal stress due to a rise in temperature does not act on the bearings 34, 36, and damage to the bearings 34, 36 due to an excessive load is prevented.

In this embodiment, the projection 94 is provided on the lower surface of the outer peripheral edge of the disc mounting portion 82. Protrusion 9
4 has a substantially rectangular cross-section, and the tip surface (lower surface) acts on the upper surface of the outer peripheral edge of the inner flange 66 of the yoke 40. Also in this embodiment, the presence of the projections 94 causes a minute gap 96 between the lower surface of the disk mounting portion 60 and the upper surface of the inner flange 66 of the yoke 40. When a large thermal stress acts on the gap 94, the elastic deformation of the projection 94 is allowed, and
In this case, free thermal deformation of the yoke 40 and the disc mounting portion 60 is allowed, and therefore, the same operation and effect as the embodiment of FIGS. 1 and 2 are achieved.

[0021]

According to the present invention, the projection for creating a gap between the hub body and the yoke is provided.
Even if a thermal stress is generated between the two due to a temperature change, the thermal stress is absorbed by the elastic deformation of the projection and the space between the yoke and the hub body, so that the hub body, especially the disk mounting portion, is prevented from being thermally deformed.

Further, according to the present invention, since the projection is provided on the hub body, the projection is easily elastically deformed.
Thermal deformation of the disk mounting portion can be effectively prevented.

Further, according to the present invention, since the projection is annular, it can be easily formed, and acts on the inner peripheral edge of the inner flange of the yoke, so that the thermal deformation of the disk mounting portion can be more effectively prevented. Can be prevented.

[Brief description of the drawings]

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

FIG. 2 is an enlarged sectional view showing the vicinity of a joint between a hub body and a yoke in the spindle motor of FIG. 1;

FIG. 3 is a sectional view showing another embodiment of the spindle motor of the present invention.

FIG. 4 is an enlarged sectional view showing the vicinity of a joint between a hub body and a yoke in a conventional spindle motor.

[Explanation of symbols]

 2, 38, 80 Hub body 4, 60 Disk mounting part 8, 40 Yoke 10, 64 Yoke body 12, 66 Inner flange 22 Bracket 24 Hub 34, 36 Bearing 42 Magnet 44 Stator 70 Projection 72 Gap

Claims (3)

[Claims] 1. A vehicle comprising: a bracket; a hub rotatable relative to the bracket; a magnet mounted on the hub; and a stator disposed facing the magnet. The hub includes a hub body on which a recording disk is mounted and a yoke on which the magnet is mounted. A disk mounting portion on which the recording disk is mounted is provided at a lower portion of the hub main body, and below the disk mounting portion. A spindle motor having the yoke mounted thereon, wherein the hub body and / or the yoke are provided with protrusions for creating a gap between the two. 2. The yoke has a cylindrical yoke main body and an inner flange protruding radially inward from an upper end of the yoke main body. The spindle motor according to claim 1, wherein the spindle motor contacts an upper surface. 3. The spindle motor according to claim 2, wherein said projection is provided annularly on a lower surface of said disk mounting portion, and abuts on an inner peripheral edge of said inner flange of said yoke.