High speed spindle motor for disc drive

• US 6,753,628 B1
• Filed: 12/22/1999
• Issued: 06/22/2004
• 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): Waks, Joseph
• Application Number:
  US09/470,428
• Time in Patent Office: 1,644 Days
• Field of Search: 310/43, 310/254, 310/89, 310/91, 310/90.5, 310/156, 310/49.R, 295/98
• 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 1/182 to stators axially facing the rotor, i.e. with axial or conical air gap
• CPC Class Codes: H02K 1/185 to outer stators
• CPC Class Codes: H02K 1/187 to inner stators
• CPC Class Codes: H02K 11/00 Structural association of dynamo-electric machines with electric components or with devices for shielding, monitoring or protection casings, enclosures or supports H02K5/00
• CPC Class Codes: H02K 11/33 Drive circuits, e.g. power electronics H02K11/38 takes precedence
• CPC Class Codes: H02K 15/10 Applying solid insulation to windings, stators or rotors
• CPC Class Codes: H02K 15/12 Impregnating, heating or drying of windings, stators, rotors or machines
• CPC Class Codes: H02K 15/14 Casings; Enclosures; Supports
• CPC Class Codes: H02K 15/16 Centering rotors within the stator; Balancing rotors
• CPC Class Codes: H02K 21/16 having annular armature cores with salient poles with homopolar co-operation H02K21/20
• CPC Class Codes: H02K 21/22 with magnets rotating around the armatures, e.g. flywheel magnetos
• CPC Class Codes: H02K 21/24 with magnets axially facing the armatures, e.g. hub-type cycle dynamos
• CPC Class Codes: H02K 2211/03 Machines characterised by circuit boards, e.g. pcb
• CPC Class Codes: H02K 3/38 around winding heads, equalising connectors, or connections thereto
• CPC Class Codes: H02K 3/46 Fastening of windings on the stator or rotor structure
• CPC Class Codes: H02K 3/47 Air-gap windings, i.e. iron-free windings
• 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 5/1672 : radially supporting the rotary shaft at both ends of the rotor H02K5/1677 takes precedence
• 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 5/1732 : radially supporting the rotary shaft at both ends of the rotor H02K5/1737 takes precedence
• 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 5/225 : Terminal boxes or connection arrangements specially adapted for submersible motors H02K5/132
• CPC Class Codes: H02K 5/24 : specially adapted for suppression or reduction of noise or vibrations
• CPC Class Codes: H02K 7/083 : radially supporting the rotary shaft at both ends of the rotor H02K7/086, H02K7/09 take precedence
• CPC Class Codes: H02K 7/085 : radially supporting the rotary shaft at only one end of the rotor H02K7/086, H02K7/09 take precedence
• CPC Class Codes: H02K 7/086 : radially supporting the rotor around a fixed spindle; radially supporting the rotor directly H02K7/09 takes precedence
• CPC Class Codes: H02K 7/088 : radially supporting the rotor directly
• CPC Class Codes: H02K 7/09 : with magnetic bearings
• CPC Class Codes: H02K 7/14 : Structural association with mechanical loads, e.g. with hand-held machine tools or fans with fan or impeller for cooling the machine H02K9/06
• CPC Class Codes: Y10T 29/49009 : Dynamoelectric machine
• CPC Class Codes: Y10T 29/49012 : Rotor

Abstract

A high speed spindle motor is constructed from 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 drive are also disclosed.

Claims

1. A motor comprising:

a) a shaft having a rotational axis;

b) a hub attached to the shaft and including a permanent magnet;

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

d) a stator comprising conductors;

e) a monolithically formed body that substantially encapsulates the stator conductors, wherein a thermoplastic material is injection molded to form the body and the body is configured to align the shaft, hub and bearing with respect to the stator, and mounting features are formed in the body to mount the motor to a device to be powered by the motor; and

f) an insert substantially encapsulated within the body, wherein the insert provides structural rigidity to the body.

2. The motor of claim 1 wherein the body surrounds the bearing.

3. The motor of claim 1 wherein the bearing comprises an upper bearing and a lower bearing.

4. The motor of claim 3 wherein the body substantially surrounds the upper bearing and the lower bearing.

5. The motor of claim 1 wherein the shaft is fixed relative to the body.

6. The motor of claim 1 wherein the shaft is freely rotatable relative to the body.

7. The motor of claim 1 wherein the mounting features are configured to allow the motor to be mounted to a hard disc drive.

8. The motor of claim 1 wherein the permanent magnet is concentrically disposed around the stator.

9. The motor of claim 1 wherein the stator concentrically surrounds the permanent magnet.

10. The motor of claim 1 wherein a second magnet is substantially encapsulated within the body.

11. The motor of claim 10 wherein the second magnet is an enhancement magnet.

12. The motor of claim 10 wherein the second magnet is part of a magnetic bearing.

13. The motor of claim 1 wherein the bearing is fixed to the body.

14. The motor of claim 1 wherein the hub comprises a disc support member and the shaft is fixed to the disc support member.

15. The motor of claim 1 wherein the stator further comprises a core and the conductors induce magnetic fields in the core when current is conducted by the conductors.

16. The motor of claim 15 wherein the core comprises steel laminations.

17. The motor of claim 15 wherein the core has a plurality of poles and the conductors comprise windings around said poles.

18. The motor of claim 1 wherein the bearing comprises ball bearings.

19. The motor of claim 18 wherein the motor comprises a high speed spindle motor and the bearings comprise oversized bearings having an outer diameter of over 13 mm.

20. The motor of claim 1 wherein the bearing is a hydrodynamic bearing.

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

22. The motor of claim 1 wherein the insert also enhances heat transfer away from the bearing and the stator.

23. The 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.

24. The motor of claim 23 wherein the body has been machined to provide precise tolerance between the first and second portions of the magnetic bearing.

25. The motor of claim 1 wherein the insert also enhances dampening of motor vibration.

26. The motor of claim 1 wherein the insert also enhances dampening of audible noise.

27. The motor of claim 1 wherein the shaft is fixed to the body and the insert is positioned between the shaft and the bearing.

28. The motor of claim 1 wherein the thermoplastic material includes ceramic particles.

29. The motor of claim 1 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.

30. The motor of claim 1 wherein the thermoplastic 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.

31. The motor of claim 1 wherein the thermoplastic 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.

32. The motor of claim 1 wherein the bearing comprises steel, the hub comprises aluminum and the thermoplastic 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.

33. The motor of claim 1 wherein the thermoplastic material comprises polyphenyl sulfide.

34. The motor of claim 1 wherein the shaft is fixed to the thermoplastic body by being molded with the stator in the thermoplastic body.

35. The motor of claim 1 wherein the bearing is fixed to the thermoplastic body with a press fit.

36. The motor of claim 1 wherein the insert is rigidly fixed to the stator by the body and is connected to the stator only through the thermoplastic material.

37. The motor of claim 36 wherein the shaft is fixed to the insert by being substantially encapsulated by the thermoplastic material.

38. The motor of claim 36 wherein the bearing is fixed to the insert by being substantially encapsulated by the thermoplastic material.

39. The motor of claim 1 herein said mounting features comprise apertures.

40. The motor of claim 1 wherein the shaft is attached to the insert.

41. A motor comprising:

a) a shaft;

b) a bearing surrounding the shaft;

c) windings acting as conductors; and

d) a monolithically formed body that substantially encapsulates at least a portion of the windings, wherein a thermoplastic material is injection molded to form the body, the material including aluminum oxide as a filler, the aluminum oxide comprising about 55% of the thermoplastic material.

42. The motor of claim 41 wherein the thermoplastic material comprises polyphenyl sulfide.

43. The motor of claim 41 wherein the thermoplastic material comprises nylon.

44. The motor of claim 41 wherein the thermoplastic material comprises polyester.

45. The motor of claim 41 wherein the thermoplastic material comprises a liquid crystal polymer.

46. A high speed spindle motor for a disc drive comprising:

a) a shaft having a rotational axis;

b) a disc support member attached to the shaft and including a permanent magnet;

c) a bearing allowing rotation of the disc support member about the rotational axis of the shaft;

d) a stator; and

e) a monolithically formed body that substantially encapsulates the stator, wherein a thermoplastic material is injection molded to form the body and the body is configured to align the shaft, disc support member and bearing with respect to the stator, and wherein the shaft is fixed to the body and an insert is substantially encapsulated within the body and is positioned between the shaft and the bearing.

47. A motor comprising:

a) a shaft having a rotational axis;

b) a hub attached to the shaft and including a permanent magnet;

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

d) a stator comprising conductors;

e) a monolithically formed body that substantially encapsulates the stator conductors, wherein a thermoplastic material is injection molded to form the body and the body is configured to align the shaft, hub and bearing with respect to the stator, and mounting features are formed in the body to mount the motor to a device to be powered by the motor; and

f) an insert substantially encapsulated within the body wherein the insert enhances heat transfer away from the bearing and the stator.

48. A motor comprising:

a) a shaft having a rotational axis;

b) a hub attached to the shaft and including a permanent magnet;

c) a bearing allowing rotation of the hub about the rotatable axis of the shaft;

d) a stator comprising conductors;

e) a monolithically formed body that substantially encapsulates the stator conductors, wherein a thermoplastic material is injection molded to form the body and the body is configured to align the shaft, hub and bearing with respect to the stator; and

mounting features are formed in the body to mount the motor to a device to be powered by the motor; and

f) an insert substantially encapsulated within the body wherein the insert enhances dampening of motor vibration.

49. A motor comprising:

a) a shaft having a rotational axis;

b) a hub attached to the shaft and including a permanent magnet;

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

d) a stator comprising conductors;

e) a monolithically formed body that substantially encapsulates the stator conductors, wherein a thermoplastic material is injection molded to form the body and the body is configured to align the shaft, hub and bearing with respect to the stator, and mounting features are formed in the body to mount the motor to a device to be powered by the motor; and

f) an insert substantially encapsulated within the body wherein the insert enhances dampening of audible noise.

50. A motor comprising:

a) a shaft having a rotational axis;

b) a hub attached to the shaft and including a permanent magnet;

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

d) a stator comprising conductors;

e) a monolithically formed body that substantially encapsulates the stator conductors, wherein a thermoplastic material is injection molded to form the body and the body is configured to align the shaft, hub and bearing with respect to the stator; and

mounting features are formed in the body to mount the motor to a device to be powered by the motor; and

f) an insert substantially encapsulated within the body, wherein the shaft is fixed to the body and the insert is positioned between the shaft and the bearing.

51. A motor comprising:

a) a shaft;

b) a bearing surrounding the shaft;

c) windings acting as conductors; and

d) a monolithically formed body that substantially encapsulates at least a portion of the windings, wherein a thermoplastic material comprising polyphenyl sulfide is injection molded to form the body, the material including aluminum oxide as a filler.