Spindle motor with encapsulated stator and method of making same

• US 6,844,636 B2
• Filed: 12/15/2000
• Issued: 01/18/2005
• Est. Priority Date: 12/17/1999
• Status: Expired due to Term

• Current Assignee: Intellectual Ventures II LLC (Intellectual Ventures LLC)
• Original Assignee: Encap Motor Corporation
• Inventors: Lieu, Dennis K., Neal, Griffith D.
• Primary Examiner(s): Waks, Joseph
• Application Number:
  US09/738,268
• Publication Number:
  US 20010045782A1
• Time in Patent Office: 1,495 Days
• Field of Search: 310/43, 310/64, 310/216, 310/179, 310/254, 310/51, 310/156.26, 295/96, 296/06, 264/272.19, 264/272.2
• US Class Current: 310/43
• CPC Class Codes: G11B 19/2009 Turntables, hubs and motors for disk drives; Mounting of motors in the drive means for clamping of disk to turntable G11B17/022 and subgroups
• CPC Class Codes: H02K 1/04 characterised by the material used for insulating the magnetic circuit or parts thereof
• CPC Class Codes: H02K 1/146 consisting of a generally annular yoke with salient poles
• CPC Class Codes: H02K 1/18 Means for mounting or fastening magnetic stationary parts on to, or to, the stator structures
• CPC Class Codes: H02K 1/185 to outer stators
• CPC Class Codes: H02K 1/187 to inner stators
• CPC Class Codes: H02K 15/12 Impregnating, heating or drying of windings, stators, rotors or machines
• CPC Class Codes: H02K 3/38 around winding heads, equalising connectors, or connections thereto
• CPC Class Codes: H02K 5/08 Insulating casings
• CPC Class Codes: H02K 5/10 with arrangements for protection from ingress, e.g. water or fingers
• CPC Class Codes: H02K 5/165 radially supporting the rotor around a fixed spindle; radially supporting the rotor directly H02K5/167, H02K5/173 take precedence
• CPC Class Codes: H02K 5/1737 radially supporting the rotor around a fixed spindle; radially supporting the rotor directly
• CPC Class Codes: Y10T 29/49009 Dynamoelectric machine
• CPC Class Codes: Y10T 29/49073 by assembling coil and core

Abstract

A spindle motor comprises a baseplate, a shaft supported by said baseplate, a stator assembly having windings, the stator being rigidly attached to said baseplate, injection molded thermoplastic material encapsulating said windings, and a hub supported on said shaft, said hub having a magnet connected thereto in operable proximity to the stator assembly. In one embodiment, the stator is coreless. In other embodiments, the stator has a core and the core is substantially encapsulated by the thermoplastic material. In preferred embodiments, the thermoplastic material secures the stator to the baseplate or forms the baseplate.

Claims

1. A hard disc drive comprising:

i) a read/write head and

ii) a spindle motor, the spindle motor comprising;

a) a baseplate;

b) a shaft supported by said baseplate;

c) a stator assembly comprising

i) a core having poles and

ii) windings around said poles;

iii) the stator core being rigidly attached to said baseplate;

d) injection molded thermoplastic material substantially encapsulating said windings and contacting the baseplate such that the windings, core and baseplate are rigidly fixed together, said thermoplastic having a modulas of elasticity of at least 1,000,000 psi at 25°

C.; and

e) a hub supported on said shaft, said hub having a magnet connected thereto in operable proximity to the stator assembly.

2. The hard disc drive of claim 1 wherein the baseplate is made of aluminum.

3. The hard disc drive of claim 1 wherein the stator assembly is rigidly attached to the baseplate by being rigidly attached to a support member secured to said baseplate.

4. The hard disc drive of claim 3 wherein the thermoplastic encapsulating the windings is adhered to said support member and said baseplate.

5. The hard disc drive of claim 1 wherein the thermoplastic used in the encapsulation has a vibratory dampening ratio of at least 0.05 in the range of 0-500 H_z.

6. The hard disc drive of claim 1 wherein the thermoplastic also encapsulates the stator core except where it is rigidly attached to the baseplate.

7. The hard disc drive of claim 1 wherein the hub is rotatably supported on said shaft by ball bearings interposed between the hub and the shaft.

8. The hard disc drive of claim 1 wherein the thermoplastic material provides a heat sink and heat conductive path from the stator assembly to the baseplate.

9. The hard disc drive of claim 1 wherein the shaft is rotatably supported by the baseplate and the hub is rigidly attached to the shaft.

10. The hard disc drive of claim 1 wherein the baseplate of the motor also constitutes the baseplate of the hard drive housing.

11. The hard disc drive of claim 1 wherein the thermoplastic material has a modulas of elasticity of at least 2,000,000 psi at 25°

C.

12. The hard disc drive of claim 1 wherein the thermoplastic material has a modulas of elasticity of at least 3,000,000 psi at 250°

C.

13. A hard disc drive comprising:

i) a read/write head and

ii) a spindle motor, the spindle motor comprising;

a) a baseplate;

b) a shaft supported by said baseplate;

c) a stator assembly comprising

i) a core having poles and

ii) windings around said poles,

the baseplate and stator assembly not being in direct contact with one another but rather the stator assembly being spaced from the baseplate;

d) a hub supported on said shaft, said hub having a magnet connected thereto in operable proximity to the stator assembly; and

e) a thermoplastic material secured to the baseplate and substantially encapsulating the stator windings, the thermoplastic material joining the stator assembly to the baseplate in the space between the stator assembly and the baseplate, filling in the space between them such that the windings, core and baseplate are rigidly fixed together.

14. The hard disc drive of claim 13 wherein the baseplate has a plurality of holes through it and the thermoplastic material is secured to the baseplate by filing in said holes.

15. The hard disc drive of claim 14 wherein the holes are enlarged on the side of the baseplate opposite to the stator assembly in order to lock the thermoplastic to the baseplate.

16. The hard disc drive of claim 13 wherein the magnet is located inside of the stator assembly.

17. The hard disc drive of claim 13 further comprising upper and lower bearings and wherein the hub comprises an outer member having an inside aperture and a ferrule fixed inside said aperture and connected directly to the bearings.

18. The hard disc drive of claim 17 wherein the magnet is attached to the ferrule.

19. The hard disc drive of claim 17 wherein bearings are interposed between the shaft and the ferrule.

20. The hard disc drive of claim 17 wherein the hub outer member is comprised of aluminum and the ferrule is comprised of steel.

21. The hard disc drive of claim 20 wherein the steel ferrule acts as flux return ring for the motor.

22. The hard disc drive of claim 13 wherein the core comprises steel laminations.

23. The hard disc drive of claim 13 wherein the hub comprises a hard drive disc support member.

24. The hard disc drive of claim 13 wherein the thermoplastic material includes ceramic particles.

25. The hard disc drive of claim 13 wherein the thermoplastic material has a coefficient of linear thermal expansion of less than 2×

10<sup>−

5</sup> in/in/°

F. throughout the range of 0-250°

F.

26. The hard disc drive of claim 13 wherein the thermoplastic material has a thermal conductivity of at least 0.7 watts/meter °

K at 23°

C.

27. The hard disc drive of claim 13 wherein the thermoplastic material has a dielectric strength for at least 250 volts/mil.

28. The hard disc drive of claim 13 wherein the thermoplastic material has a vibration dampening ratio of at least 0.05 in a frequency range of 0-500 Hz and a modulas of elasticity of at least 1,000,000 psi at 25°

C.

29. The hard disc drive of claim 13 wherein the baseplate comprises a stiff thermoplastic material, having a modulas of elasticity of at least 1,000,000 psi, and a metal plate substantially encapsulated in the stiff thermoplastic material.

30. The hard disc drive of claim 29 wherein the stiff thermoplastic material is the same material as is used to encapsulate the windings.

31. The hard disc drive of claim 13 wherein the magnet is adjacent an inside diameter of the stator.

32. The hard disc drive of claim 13 wherein the thermoplastic used in the encapsulation has a vibratory dampening ratio of at least 0.05 in the range of 0-500 Hz.

33. The hard disc drive of claim 13 wherein the thermoplastic material has a modulas of elasticity of at least 2,000,000 psi at 250°

C.

34. The hard disc drive of claim 13 wherein the thermoplastic material has a modulas of elasticity of at least 3,000,000 psi at 25°

C.

35. A spindle motor comprising:

a) a baseplate made of stiff thermoplastic material, having a modulas of elasticity of at least 1,000,000 psi at 25°

C., and a metal plate substantially encapsulated by the stiff thermoplastic material;

b) a shaft supported by said baseplate;

c) a stator assembly comprising

i) a core having poles and

ii) windings around said poles;

d) a hub supported on said shaft, said hub having a magnet connected thereto in operable proximity to the stator assembly; and

e) a vibration dampening thermoplastic material encapsulating the stator windings, the vibration dampening thermoplastic material having a vibration dampening ratio of at least 0.05 in the range of 0-500 Hz and joining the stator assembly to the baseplate.

36. The spindle motor of claim 35 wherein the stiff thermoplastic material is the same material as the vibration dampening thermoplastic material.

37. The spindle motor of claim 35 wherein the vibration dampening material has a vibration dampening ratio of at least 0.1 in the range of 0-500 Hz.

38. The spindle motor of claim 35 wherein the vibration dampening thermoplastic material has a vibration dampening ratio of at least 0.3 in the range of 0-500 Hz.

39. The spindle motor of claim 35 wherein the vibration dampening thermoplastic material has a vibration-dampening ratio of at least 0.5 in the range of 0-500 Hz.

40. The spindle motor of claim 35 wherein the stiff thermoplastic material has a modulas of elasticity of at least 2,000,000 psi at 25°

C.

41. The spindle motor of claim 35 wherein the stiff thermoplastic material has a modulas of elasticity of at least 3,000,000 psi at 25°

C.

42. The spindle motor of claim 35 wherein the hub is rotatably supported on the shaft and the shaft is rigidly attached to the baseplate.

43. A hard disc drive including the motor of claim 35.

44. A hard disc drive comprising:

i) a read/write head and

ii) a spindle motor, the spindle motor comprising;

a) a baseplate made of stiff thermoplastic material, having a modulas of elasticity of at least 1,000,000 psi at 25°

C., and a metal plate substantially encapsulated by the stiff thermoplastic material;

b) a shaft supported by said baseplate;

c) a stator assembly comprising

i) a core having poles and

ii) windings around said poles;

d) a hub supported on said shaft, said hub having a magnet connected thereto in operable proximity to the stator assembly; and

e) a vibration dampening thermoplastic material encapsulating the stator windings, the vibration dampening thermoplastic material having a vibration dampening ratio of at least 0.05 in the range of 0-500 Hz and joining the stator assembly to the baseplate.

45. The hard disc drive of claim 44 wherein the stiff thermoplastic material is the same material as the vibration dampening thermoplastic material.

46. The hard disc drive of claim 44 wherein the vibration dampening material has a vibration dampening ratio of at least 0.1 in the range of 0-500 Hz.

47. The hard disc drive of claim 44 wherein the vibration dampening thermoplastic material has a vibration dampening ratio of at least 0.3 in the range of 0-500 Hz.

48. The hard disc drive of claim 44 wherein the vibration dampening thermoplastic material has a vibration-dampening ratio of at least 0.5 in the range of 0-500 Hz.

49. The hard disc drive of claim 44 wherein the stiff thermoplastic material has a modulas of elasticity of at least 2,000,000 psi at 250°

C.

50. The hard disc drive of claim 44 wherein the stiff thermoplastic material has a modulas of elasticity of at least 3,000,000 psi at 25°

C.

51. The hard disc drive of claim 44 wherein the hub is rotatably supported on the shaft and the shaft is rigidly attached to the baseplate.

52. A spindle motor comprising:

a) a baseplate;

b) a shaft supported by said baseplate;

c) a stator assembly comprising

i) a core having poles and

ii) windings around said poles,

the baseplate and stator assembly not being in direct contact with one another but rather the stator assembly being spaced from the baseplate;

d) a hub supported on said shaft, wherein the hub comprises a hard drive disc support member, said hub having a magnet connected thereto in operable proximity to the stator assembly; and

e) a thermoplastic material secured to the baseplate and substantially encapsulating the stator windings, the thermoplastic material joining the stator assembly to the baseplate in the space between the stator assembly and the baseplate, filling in the space between them such that the windings, core and baseplate are rigidly fixed together.

53. A spindle motor comprising:

a) a baseplate comprising a stiff thermoplastic material, having a modulas of elasticity of at least 1,000,000 psi, and a metal plate substantially encapsulated in the stiff thermoplastic material;

b) a shaft supported by said baseplate;

c) a stator assembly comprising

i) a core having poles and

ii) windings around said poles,

the baseplate and stator assembly not being in direct contact with one another but rather the stator assembly being spaced from the baseplate;

d) a hub supported on said shaft, said hub having a magnet connected thereto in operable proximity to the stator assembly; and

e) a thermoplastic material secured to the baseplate and substantially encapsulating the stator windings, the thermoplastic material joining the stator assembly to the baseplate in the space between the stator assembly and the baseplate, filling in the space between them such that the windings, core and baseplate are rigidly fixed together.

54. The spindle motor of claim 53, wherein the stiff thermoplastic material used in the baseplate is the same material as is used to encapsulate the windings.