Spindle motor

Abstract

The invention relates to a spindle motor having a fluid dynamic bearing system used particularly for driving the storage disks of hard disk drives, having a baseplate, a stationary bearing bush disposed in an opening in the baseplate, a shaft rotatably supported in an axial bore in the bearing bush by means of the fluid dynamic bearing system, a hub connected to the shaft, and an electromagnetic drive system. In order to increase the stiffness of the motor system, according to the invention the bearing bush is provided with a flange that is fixed in the opening in the baseplate and whose outside diameter is distinctly larger than the outside diameter of the bearing bush. Instead of a flange at the outer diameter of the bearing bush there can be provided a sleeve at the base plate which receives the bearing bush at least partly.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a section through a first embodiment of a spindle motor having a widened, flange-like bearing bush.

FIG. 2 shows a section through a second embodiment of a spindle motor having a flange ring between the bearing bush and the baseplate.

FIG. 3 shows a section through a third embodiment of a spindle motor having a widened, flange-like bearing bush and inserted damping elements.

FIG. 4 shows a section through a fourth embodiment of a spindle motor having a flange ring between the bearing bush and the baseplate and a damping element at the outside diameter of the flange ring.

FIG. 5 shows a section through a fifth embodiment of a spindle motor having a flange ring between the bearing bush and the baseplate and damping elements at the inside and at the outside diameter of the flange ring.

FIG. 6 shows a section through a sixth embodiment of a spindle motor having a flange ring between the bearing bush and the baseplate and a damping element at the conically tapered outside diameter of the flange ring.

FIG. 7 shows a comparison of the vibration transfer function of a spindle motor according to the prior art and a spindle motor according to the invention in accordance with FIG. 1.

FIG. 8 shows a comparison of the vibration transfer function of a conventional spindle motor and a spindle motor according to the invention in accordance with FIG. 3 without a damping element and with damping elements of different thicknesses.

FIG. 9 shows a section through a seventh embodiment of a spindle motor having a damping element between a substantially cylindrical bearing bush and the base plate.

Claims

1. A spindle motor (10; 110) having a fluid dynamic bearing system used particularly for driving the storage disks of hard disk drives, having a baseplate (12), a stationary bearing bush (14; 114) disposed in an opening in the baseplate, a shaft (18) rotatably supported in an axial bore in the bearing bush by means of the fluid dynamic bearing system, a hub (22) connected to the shaft, and an electromagnetic drive system (30, 32), characterized in that the bearing bush (14; 114) has a flange (16; 116) that is fixed in the opening in the baseplate (12) and whose outside diameter is substantially larger than the outside diameter of the bearing bush, and that a damping element (34; 134) is disposed at a joint between a flange (16; 116) and the baseplate (12) and/or the flange (116) and the bearing bush (14; 114).

2. A spindle motor according to claim 1, characterized in that the outside diameter of the flange (16; 116) is at least 1.5 times the outside diameter of the bearing bush.

3. A spindle motor according to claim 1, characterized in that the outside diameter of the flange (16; 116) is substantially the same as the outside diameter of the hub (22).

4. A spindle motor according to claim 1, characterized in that the flange (16) is integrally formed with the bearing bush (14).

5. A spindle motor according to claim 1, characterized in that the flange comprises a flange ring (116) connected to the bearing bush (114).

6. A spindle motor according to claim 5, characterized in that at least one interface between the flange (16; 116) and the baseplate (12) and/or between the flange ring (116) and the bearing bush (114) is conical in shape.

7. A spindle motor according to claim 1, characterized in that the flange (16; 116) is made of a material having an elasticity module E>=70 GPa.

8. A spindle motor according to claim 1, characterized in that the flange (16; 116) is made either of metal, of a metal alloy, of a ceramic material or of a plastic.

9. A spindle motor according to claim 5, characterized in that the damping element (34) is disposed between the outside diameter of the flange ring (116) and the inside diameter of the opening in the baseplate (12).

10. A spindle motor according to claim 5, characterized in that the damping element (134) is disposed between the inside diameter of the flange ring (116) and the outside diameter of the bearing bush (114).

11. A spindle motor according to claim 1, characterized in that the damping element (34) is disposed between the outside diameter of the flange (16) and the inside diameter of the opening in the baseplate (12).

12. A spindle motor according to claim 1, characterized in that the damping element (34; 134) has a thickness of between 10 and 100 μm.

13. A spindle motor according to claim 1, characterized in that the damping element (34; 134) is made of a viscoelastic material.

14. A spindle motor according to claim 13, characterized in that the damping element (34; 134) is made of a viscoelastic polymer foil.

15. A spindle motor according to claims 1, characterized in that the damping element (34; 134) is connected to a flange or a flange ring and the baseplate or the bearing bush (14) by means of bonding.

16. A spindle motor (410) having a fluid dynamic bearing system used particularly for driving the storage disks of hard disk drives, having a baseplate (412), a stationary bearing bush (414) disposed in an opening in the baseplate, a shaft (418) rotatably supported in an axial bore in the bearing bush by means of the fluid dynamic bearing system, a hub (422) connected to the shaft, and an electromagnetic drive system (430, 432), characterized in that the baseplate (412) has a sleeve (436) which supports the bearing bush (414), wherein the connection length V between the bearing bush (414) and the sleeve (436) is at least one third of the overall length L of the bearing bush (414), and that a damping element (434) is disposed at a joint between the bearing bush (414) and the sleeve (436).

17. A spindle motor according to claim 16, characterized in that the damping element (434) has a thickness of between 10 and 100 μm.

18. A spindle motor according to claim 16, characterized in that the damping element (434) is made of a viscoelastic material.

19. A spindle motor according to claim 18, characterized in that the damping element (434) is made of a viscoelastic polymer foil.

20. A spindle motor according to claims 16, characterized in that the damping element (434) is connected to the bearing bush (414) and the sleeve (436) by means of bonding.