High speed spindle motor

• US 6,617,721 B1
• Filed: 12/22/1999
• Issued: 09/09/2003
• Est. Priority Date: 07/29/1999
• Status: Expired due to Term

• Current Assignee: Intellectual Ventures II LLC (Intellectual Ventures LLC)
• Original Assignee: Encap Motor Corporation
• Inventors: Neal, Griffith D.
• Primary Examiner(s): Lam, Thanh
• Application Number:
  US09/470,434
• Time in Patent Office: 1,357 Days
• Field of Search: 310/68.D, 310/43, 310/67.R, 310/254
• US Class Current: 310/68.00D
• 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 1/146 consisting of a generally annular yoke with salient poles
• CPC Class Codes: H02K 1/185 to outer stators
• CPC Class Codes: H02K 1/187 to inner stators
• CPC Class Codes: H02K 3/46 Fastening of windings on the stator or rotor structure
• CPC Class Codes: H02K 5/02 Casings or enclosures characterised by the material thereof
• CPC Class Codes: H02K 5/08 Insulating casings
• CPC Class Codes: H02K 5/1675 radially supporting the rotary shaft at only one end of the rotor H02K5/1677 takes precedence
• CPC Class Codes: H02K 5/1677 radially supporting the rotor around a fixed spindle; radially supporting the rotor directly
• CPC Class Codes: H02K 5/1735 radially supporting the rotary shaft at only one end of the rotor H02K5/1737 takes precedence
• CPC Class Codes: H02K 5/1737 radially supporting the rotor around a fixed spindle; radially supporting the rotor directly
• CPC Class Codes: H02K 7/085 radially supporting the rotary shaft at only one end of the rotor H02K7/086, H02K7/09 take precedence

Abstract

The present invention is directed to a high speed spindle motor comprising a stator assembly including a stator having multiple conductors that create a plurality of magnetic fields when electrical current is conducted by the conductors and a body of a phase change material such as a thermoplastic substantially encapsulating the stator. A rotatable hub having a magnet connected thereto is in operable proximity to the stator. The high speed motor also includes a shaft, a bearing surrounding the shaft and one of the bearing or shaft being fixed to the stator assembly and the other of the bearing or shaft being fixed to the rotatable hub. Hard disc drives using the motor, and methods of developing and constructing the motor and hard disc drives are also disclosed.

Claims

1. A high speed spindle motor comprising:

a) a stator assembly comprising;

i) a stator having multiple conductors that create a plurality of magnetic fields when electrical current is conducted by the conductors; and

ii) a body of a phase change material substantially encapsulating the stator so as to rigidly fix the stator and body together;

b) a rotatable hub having a magnet connected thereto in operable proximity to the stator;

c) a shaft;

d) a bearing around the shaft; and

e) one of the shaft or bearing being fixed to the stator assembly by the body of phase change material and being in contact therewith; and

the other of the shaft or bearing being fixed to the rotatable hub.

2. The high speed spindle motor of claim 1 wherein the body of phase change material is a monolithic body.

3. The high speed motor of claim 1 wherein the bearing is fixed to the stator assembly.

4. The high speed motor of claim 1 wherein the shaft is fixed to the stator assembly.

5. The high speed motor of claim 3 wherein the stator further comprises a core and the conductors induce magnetic fields in the core when current is conducted by the conductors.

6. The high speed motor of claim 5 wherein the core comprises steel laminations.

7. The high speed motor of claim 5 wherein the core has a plurality of poles and the conductors comprise windings around said poles.

8. The high speed motor of claim 1 wherein the conductors comprise a plurality of windings.

9. The high speed motor of claim 8 wherein the spindle motor comprises a pancake motor and the conductors comprise windings mounted on a circuit board.

10. The high speed motor of claim 1 wherein the conductors comprise electrical traces on a circuit board.

11. The high speed motor of claim 1 wherein the hub comprises a hard drive disc support member.

12. The high speed motor of claim 1 wherein the motor is able to operate at at least 10,000 rpm.

13. The high speed motor of claim 1 wherein the magnet connected to the hub is a permanent magnet.

14. The high speed motor of claim 1 wherein the bearing includes an upper bearing and a lower bearing.

15. The high speed motor of claim 14 wherein the body surrounds the upper bearing and the lower bearing.

16. The high speed motor of claim 1 wherein the stator assembly further comprises terminals for connecting the conductors to a power source external to the motor.

17. The high speed motor of claim 16 wherein the terminals are partially encapsulated within the body.

18. The high speed motor of claim 1 wherein apertures are formed within the body for mounting the high speed motor to a hard disc drive.

19. The high speed motor of claim 1 wherein the magnet is concentrically disposed around the stator.

20. The high speed motor of claim 1 wherein the bearing comprises ball bearings.

21. The high speed motor of claim 20 wherein the bearings comprise oversized bearings having an outer diameter of over 13 mm.

22. The high speed motor of claim 1 wherein the bearing is a hydrodynamic bearing.

23. The high speed motor of claim 1 wherein the stator concentrically surrounds the magnet.

24. The high speed motor of claim 1 wherein the phase change material comprises a material that changes from a liquid to a solid due to a change in temperature.

25. The high speed motor of claim 24 wherein the phase change material comprises a thermoplastic material.

26. The high speed motor of claim 24 therein the phase change material comprises a thermosetting material.

27. The high speed motor of claim 24 wherein the phase change material comprises a material that changes from a liquid to a solid due to a chemical reaction.

28. The high speed motor of claim 27 wherein the phase change material comprises an epoxy.

29. The high speed motor of claim 1 wherein the stator and magnet are generally coplanar.

33. The high speed motor of claim 1 wherein a first portion of a magnetic bearing is substantially encapsulated within the body and a second opposing portion of the magnetic bearing is attached to the hub.

34. The high speed motor of claim 33 wherein the body has been machined to provide precise tolerance between the first and second portions of the magnetic bearing.

39. The high speed motor of claim 1 wherein an enhancement magnet is substantially encapsulated within the body.

40. The high speed motor of claim 1 wherein a thermoplastic material is injection molded to form the body.

41. The high speed motor of claim 40 wherein the thermoplastic body is monolithic.

42. The high speed motor of claim 1 wherein the phase change material includes ceramic particles.

43. The high speed motor of claim 1 wherein the phase change 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.

44. The high speed motor of claim 1 wherein the phase change material has a coefficient of linear thermal expansion of less than 1.5×

10<sup>−

5</sup> in/in/°

F. throughout the range of 0-250°

F.

45. The high speed motor of claim 1 wherein the phase change material has a coefficient of linear thermal expansion of between about 0.8×

10<sup>−

5</sup> in/in/°

F. and about 1.2×

10<sup>−

5</sup> in/in/°

F. throughout the range of 0-250°

F.

46. The high speed motor of claim 1 wherein the bearing comprises steel, the hub comprising aluminum and phase change material has a coefficient of linear thermal expansion that is between the coefficient of linear thermal expansion of the steel and the coefficient of linear thermal expansion of the aluminum.

47. The high speed motor of claim 1 wherein the phase change material has a thermal conductivity of at least 0.7 watts/meter°

K at 23°

C.

48. The high speed motor of claim 1 wherein the phase change material comprises polyphenyl sulfide.

49. The high speed motor of claim 1 wherein the phase change material has a dielectric strength of at least 250 volts/mil.

50. The high speed motor of claim 49 wherein the phase change material has a thermal conductivity of at least 0.7 watts/meter°

K at 23°

C.

30. A high speed spindle motor comprising:

a) a stator assembly comprising;

i) a stator having multiple conductors that create a plurality of magnetic fields when electrical current is conducted by the conductors;

ii) a body of a phase change material substantially encapsulating the stator so as to rigidly fix the stator and body together; and

iii) a solid insert substantially encapsulated within the body;

b) a rotatable hub having a magnet connected thereto in operable proximity to the stator;

c) a shaft;

d) a bearing around the shaft; and

e) one of the shaft or bearing being fixed to the stator assembly and the other of the shaft or bearing being fixed to the rotatable hub.

31. The high speed motor of claim 30 wherein the insert provides structural rigidity to the stator assembly.

32. The high speed motor of claim 30 therein the insert enhances heat transfer away from the bearing and the stator.

35. The high speed motor of claim 30 wherein the insert enhances dampening of motor vibration.

36. The high speed motor of claim 30 wherein the insert enhances dampening of audible noise.

37. The high speed motor of claim 30 wherein the shaft is fixed to the body and the insert is positioned between the shaft and the bearing.

38. The high speed motor of claim 37 wherein the bearing comprises an oversized bearing having an outer diameter of over 13 mm.

51. A high speed spindle motor comprising:

a) a stator substantially encapsulated in a thermoplastic body so as to rigidly fix the stator and body together, the thermoplastic body having a cylindrical hole therein;

b) a bearing press fit into the cylindrical hole in contact with the thermoplastic body;

c) a shaft rotatably supported by the bearing; and

d) a hub having a magnet connected thereto, the hub being fixed to the shaft.

52. A motor comprising:

a) a stator assembly comprising;

i) a stator having at least one conductor and a plurality of magnetic fields when electrical current is conducted by the at least one conductor; and

ii) a body of a phase change material substantially encapsulating the stator so as to rigidly fix the stator and body together, the phase change material including ceramic particles;

b) a magnet in operable proximity to the stator;

c) a shaft having a rotational axis;

d) a bearing allowing rotation about the rotational axis of the shaft; and

e) one of the shaft or bearing being fixed to the stator assembly.

53. A motor comprising:

a) a stator assembly comprising;

i) a stator having at least one conductor and a plurality of magnetic fields when electrical current is conducted by the at least one conductor; and

ii) a body of a phase change material substantially encapsulating the stator so as to rigidly fix the stator and body together, the phase change material having a coefficient of linear thermal expansion of less than 2×

10<sup>−

5</sup> in/in/°

F. throughout the range of 0-250°

F.;

b) a magnet in operable proximity to the stator;

c) a shaft having a rotational axis;

d) a bearing allowing rotation about the rotational axis of the shaft; and

e) one of the shaft or bearing being fixed to the stator assembly.

54. A motor comprising:

a) a stator assembly comprising;

i) a stator having at least one conductor and a plurality of magnetic fields when electrical current is conducted by the at least one conductor; and

ii) a body of a phase change material substantially encapsulating the stator so as to rigidly fix the stator and body together, the phase change material having a thermal conductivity of at least 0.7 watts/meter°

K at 23°

C.;

b) a magnet in operable proximity to the stator;

c) a shaft having a rotational axis;

d) a bearing allowing rotation about the rotational axis of the shaft; and

e) one of the shaft or bearing being fixed to the stator assembly.

55. A motor comprising:

a) a shaft having a rotational axis;

b) a bearing allowing rotation about the rotational axis of the shaft;

c) windings acting as conductors; and

d) an injection molded thermoplastic with a thermal conductivity of at least 0.7 watts/meter °

K at 23°

C. encapsulating at least a portion of the windings.

56. The motor of claim 55 wherein the thermoplastic is filled with aluminum oxide.

57. The motor of claim 55 wherein a bearing is attached to and contacts the thermoplastic.

58. The motor of claim 55 wherein the shaft is attached to and contacts the thermoplastic.

59. A motor comprising:

a) At least one wire winding acting as a conductor;

b) at least one terminal which is electrically connected to the wire winding; and

c) an injection molded thermoplastic filled with aluminum oxide encapsulating at least a portion of the terminal at a point of its connection.

60. The motor of claim 59 where the linear coefficient of thermal expansion of the thermoplastic is less than 2.0×

10<sup>−

5</sup> in/in/°

F. throughout the range of 0-250°

F.

61. The motor of claim 59 where the terminal is a copper pad.