Stator assembly made from a plurality of toroidal core segments and motor using same

• US 7,036,207 B2
• Filed: 03/02/2001
• Issued: 05/02/2006
• Est. Priority Date: 03/02/2001
• 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): Compton, Eric
• Application Number:
  US09/798,511
• Publication Number:
  US 20020135263A1
• Time in Patent Office: 1,887 Days
• Field of Search: 295/96, 295/98, 295/97, 296/05, 296/06, 297/32, 310/214, 310/216, 310/45, 310/154, 310/156, 310/218
• US Class Current: 29/597
• 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 1/148 Sectional cores H02K1/141 takes precedence
• CPC Class Codes: H02K 15/022 with salient poles or claw-shaped poles
• CPC Class Codes: H02K 15/095 by laying conductors around salient poles
• CPC Class Codes: H02K 15/12 Impregnating, heating or drying of windings, stators, rotors or machines
• CPC Class Codes: H02K 2203/06 Machines characterised by the wiring leads, i.e. conducting wires for connecting the winding terminations
• CPC Class Codes: H02K 3/522 for generally annular cores with salient poles
• CPC Class Codes: H02K 5/08 Insulating casings
• 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 29/49011 Commutator or slip ring assembly
• CPC Class Codes: Y10T 29/49012 Rotor
• CPC Class Codes: Y10T 29/49073 by assembling coil and core
• CPC Class Codes: Y10T 29/53143 Motor or generator

Abstract

A plurality of stator arc segments form a toroidal core for a stator assembly used to make a motor. In a preferred embodiment, a plurality of magnetic fields is created when electrical current is conducted through wire wound around poles on the toroidal core. A monolithic body of phase change material substantially encapsulates the conductors and holds the stator arc segments in contact with each other in the toroidal core. Hard disc drives using the motor, and methods of constructing the motor and hard disc drives are also disclosed.

Claims

1. A stator assembly, comprising:

a) a plurality of individual stator arc segments forming a toroidal core, wherein each said stator arc segment has two end surfaces and a plurality of poles with wire wound around said poles forming the toroidal core; and

b) a monolithic body of injection molded thermoplastic material substantially encapsulating the stator arc segments and the wire wound around the poles, wherein said thermoplastic material bonds the arc segments together to hold the arc segments in a toroidal shape, the monolithic body of thermoplastic material being the sole structure functioning to secure the arc segments in the toroidal shape.

2. The stator assembly of claim 1 wherein the packing density of the wire around the poles is between about 60 percent and about 80 percent.

3. The stator assembly 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.

4. The stator assembly 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.

5. The stator assembly 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.

6. The stator assembly of claim 1 wherein the thermoplastic material has a thermal conductivity of at least 0.7 watts/meter°

K at 23°

C.

7. The stator assembly of claim 1 wherein the thermoplastic material comprises polyphenyl sulfide.

20. A motor comprising the stator assembly of claim 1.

21. The motor of claim 20 wherein said motor comprises said stator assembly, a shaft, a base, bearings, a rotor, at least one permanent magnet and a hub.

22. An electronic device including the motor of claim 20.

23. A motor and disc assembly including the motor of claim 20.

27. The stator assembly of claim 1 wherein said end surfaces of adjacent stator arc segments are in contact with one another.

8. A method of making a stator assembly for a motor comprising:

a) providing at least two individual stator arc segments each having a first end surface and a second end surface and a plurality of poles with wire wound around said poles;

b) aligning said stator arc segments to form a toroidal core; and

c) substantially encapsulating said toroidal core, including said windings, with a monolithic body of injection molded thermoplastic material to form said stator assembly, wherein said 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. and bonds the arc segments together to hold the arc segments in a toroidal shape.

9. The method of claim 8 wherein the poles extend inwardly from a base of each of said stator arc segments.

10. The method of claim 9 wherein prior to said step of aligning, the wire is wound around said poles of said stator arc segments.

11. The method of claim 10 wherein said stator arc segments are placed in a carrier that holds and supports said stator arc segments while the wire is wound around said poles.

12. The method of claim 11 wherein said carrier has a plurality of cavities to hold and support said stator arc segments.

13. The method of claim 12 wherein said cavities are spaced apart a distance X, wherein X is the length of uncoiled wire necessary to align said stator arc segments to form a toroidal core.

14. The method of claim 8 wherein said windings provide multiple conductors that create a plurality of magnetic fields when electrical current is conducted through the conductors.

15. The method of claim 8 wherein prior to said substantially encapsulating, said toroidal core is clamped in an injection mold cavity to maintain the toroidal shape.

16. The method of claim 8 wherein said thermoplastic material is injected into a mold at temperature of between about 200°

F. and about 700°

F.

17. The method of claim 8 wherein said thermoplastic material is injected into a mold at a temperature of between about 550°

F. to about 650°

F.

24. The method of claim 10 wherein the packing density of the wire around the poles is between about 60 percent and about 80 percent.

26. The method of claim 8 wherein the thermoplastic material has a thermal conductivity of at least 0.7 watts/meter°

K at 23°

C.

28. The method of claim 8 wherein said end surfaces of adjacent stator arc segments are in contact with one another.

18. A method of making a motor comprising:

a) providing a plurality of individual stator arc segments, wherein each stator arc segment has a first end surface and a second end surface and three poles with wire wound around said poles;

b) aligning said stator arc segments to form a toroidal core;

c) substantially encapsulating said toroidal core, including said windings, with a monolithic body of thermoplastic material, wherein said substantially encapsulating is by injection molding said thermoplastic material around said toroidal core to form a stator assembly, wherein said thermoplastic material bonds the arc segments together to hold the arc segments in a toroidal shape, the monolithic body of thermoplastic material structurally functioning to secure the core in the toroidal shape; and

d) constructing the stator assembly into a motor.

19. The method of claim 18 wherein each of said stator arc segments comprise a plurality of steel laminations.

25. The method of claim 18 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.

29. The method of claim 18 wherein said end surfaces of adjacent stator arc segments are in contact with one another.