JP3383016B2 - Spindle motor - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a spindle motor mounted on, for example, an optical / magnetic disk device and used for rotating a recording disk. .5
The present invention relates to a spindle motor suitable for driving small recording disks such as inches and 2.5 inches. 2. Description of the Related Art A spindle motor used for driving a magnetic disk or the like has a function of mounting one or more disks as a load on a hub and rotating the hub. 2. Description of the Related Art In recent years, as optical and magnetic disk devices have become smaller and lighter, there has been a demand for smaller and lighter spindle motors. A spindle motor as shown in FIG. 3 is known as one that satisfies such a demand. The spindle motor 1 has a hub 7 having a bracket 2 composed of a base, a frame, and the like, and a central column 6 rotatably supported by a pair of bearings 4 and 5 inside an annular rising portion 3 provided on the bracket 2. And is composed of A known stator 8 is provided outside the annular rising portion 3 of the bracket 2.
Are fixedly arranged. An insulating sheet 9 made of resin is provided on the surface of the bracket 2 that receives the stator 8 to ensure insulation of the stator 8. Further, the hub 7 has a hanging portion 10 hanging down toward the bracket 2 on an outer peripheral portion thereof, and a flange portion 12 for supporting a disk 11 is formed on an outer peripheral edge thereof. A rotor magnet 13 is provided inside the hanging portion 10 at a position facing the stator 8.
Has been fixed. [0004] The disk 11 is disposed on the flange portion 12 of the hub 7, a clamp member 14 is disposed on the upper surface of the disk 11, and the clamp member 14 is fixed by a mounting screw 15 which is screwed into a screw hole provided in the hub 7. By doing so, the disk 11 is fixed to the hub 7. As a result, the disk 11 rotates together with the hub 7 at the same time as the hub 7 rotates. [0005] In the conventional spindle motor, the bracket 2 and the hub 7 are made of aluminum or iron, respectively, in order to reduce the size and weight.
And a material containing iron or aluminum as a main raw material, and the material is formed as thin as possible. As a result, the objective of reducing the size and weight of the initial spindle motor has been achieved to some extent. However, the spindle motor is too light and generates fine vibrations when the motor is driven. As a result, a new problem arises in that metallic noise, so-called pure tone, is generated. SUMMARY OF THE INVENTION [0007] In order to solve the above-mentioned problems, the present invention solves the above-mentioned problems.
And it intended to prevent the occurrence of pure tones by configuring the large brass material specific gravity than iron
is there. According to the present invention, the hub made of brass material having a large specific gravity presses the bracket from above, thereby preventing the bracket from vibrating. Hereinafter, the present invention will be described in detail with reference to the drawings. FIG. 1 is a sectional view of a spindle motor 20 showing an embodiment of the present invention. The structure of the spindle motor 20 is substantially the same as the known structure described in FIG. That is, the spindle motor 20 includes a bracket 22 formed of a base, a frame, and the like made of an iron or aluminum material , and a pair of bearings 26 fixed vertically above an annular rising portion 24 provided integrally with the bracket 22. , 28 and a hub 32 having a central post 30 rotatably supported by the hub. Wherein the hub 32 is made form <br/> by brass of density 8.65. A known stator 34 is fixedly disposed outside the annular upright portion 24 of the bracket 22. An insulating sheet 36 made of resin is provided on the surface of the bracket 22 that receives the stator 34 to ensure insulation between the stator 34 and the bracket 22. The hub 32 has a hanging portion 38 hanging down toward the bracket 22 on the outer peripheral portion thereof, and a flange portion 42 for supporting the disk 40 is formed on the outer peripheral edge thereof. The hanging part 38
A rotor magnet 44 is fixed at a position facing the stator 34 inside the rotor. The disk 40 is a flange 42 of the hub 32.
And the clamp member 46 is disposed on the upper surface of the disc 40, and the disc 40 is fixed to the hub 32 by fixing the clamp member 46 with a mounting screw 48 screwed into a screw hole provided in the hub 32. It is fixed. As a result, the disc 32
0 also rotates with the hub 32. The insulating sheet 36 has an annular shape as shown in FIG. 2, and can be inserted into the annular rising portion 24 of the bracket 22. Further, the insulating sheet 9 is provided with a plurality of punched holes 50 at substantially equal intervals in the circumferential direction. Therefore, before fixing the stator 34 to the annular upright portion 24 of the bracket 22, the insulating sheet 36 is inserted and arranged in the annular upright portion 24 of the bracket 22. Thereafter, the sheet 36 is pressed against the surface of the bracket 22. Next, an adhesive 52 is injected from the upper surface of the punched hole 50. The injected adhesive flows into the space between the sheet 36 and the bracket 22 through the hole 50 to join the two. At the same time, the adhesive 50 accumulated on the upper part of the hole 50
Are arranged in a raised state above the hole 50. Therefore, the insulating sheet 36 is completely fixed to the bracket 22 as if it were fixed by the eyelet member. If necessary, the portion of the adhesive 52 laminated on the upper surface of the insulating sheet 36 can be cut off by a member such as a knife. In the above embodiment, the present invention has been described as applied to a rotating shaft type motor. However, the present invention can be similarly applied to a fixed shaft type motor. In this case, the shaft member is fixed to the bracket, and the hub is rotatably mounted on the shaft member via a pair of bearings. According to the present invention, the specific gravity of iron is 7.
By configuring the hub with brass material having a specific gravity of 8.65 greater than 87, the hub presses the bracket from above by its own weight, thereby preventing the bracket from vibrating. For this reason, generation of a very unpleasant pure tone can be prevented .

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a sectional view of a spindle motor according to the present invention. FIG. 2 shows an insulating sheet used in the spindle motor according to the present invention, in particular, A is a plan view thereof;
B shows a sectional view thereof. FIG. 3 is a sectional view of a known spindle motor.

Continuation of the front page (56) References JP-A-5-68395 (JP, A) JP-A-4-355650 (JP, A) JP-A-4-304137 (JP, A) JP-A-4-208053 (JP) JP-A-3-268480 (JP, A) JP-A-2-276450 (JP, A) JP-A 61-48472 (JP, U) JP-A 4-131178 (JP, U) (58) Field surveyed (Int. Cl. ⁷ , DB name) H02K 29/00 H02K 5/24 H02K 21/22

Claims (1)

(57) [Claims 1] Formed from iron or aluminum material
And a bracket 22, located above the bracket 22
And a hub 32 rotatably supported by the bracket 22 via bearings 26 and 28, and a stator 34 is fixedly disposed on the bracket 22. The hub 32 covers the stator 34. As described above, the outer peripheral portion has a hanging portion 38 hanging down toward the bracket 11, and a flange portion 42 for supporting the disk 40 is formed on the outer circumferential edge thereof. The rotor magnet 44 is fixed at the opposed position,
And a hub 32 having a specific gravity greater than that of the material of the bracket 22.
A spindle motor formed of brass material .