Stator assembly made from a molded web of core segments and motor using same

• US 20040034988A1
• Filed: 03/05/2003
• Published: 02/26/2004
• Est. Priority Date: 03/02/2001
• Status: Active Grant

• Current Assignee: Intellectual Ventures II LLC (Intellectual Ventures LLC)
• Original Assignee: Encap Technologies, Inc. (Encap Holding Company)
• Inventors: Neal, Griffith D.
• Granted Patent: US 7,067,952 B2
• Time in Patent Office: Days
• US Class Current: 29/596
• 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 20 are linked together by a phase change material 22 enabling simplified winding and higher slot fill. Once wound this continuous structure can be formed into a toroidal core 17 for a stator assembly 40 used to make a motor 100. In a preferred embodiment, a monolithic body 42 of phase change material substantially encapsulates the conductors and holds the stator arc segments 20 in contact with each other in the toroidal core 17. Hard disc drives using the motor 100, and methods of constructing the motor 100 are also disclosed.

Claims

1. A stator assembly, comprising:

a) a plurality of discrete stator segments each at least partially encased with a phase change material, wherein the phase change material also comprises a bridge between adjacent segments to link adjacent segments into a continuous strip; and

b) the linked stator segments being arranged and secured together to form the stator assembly.

2. The stator assembly of claim 1 wherein the bridges produce such a continuous linkage between segments that the bridges may be used to orient and manipulate the segments during wire winding.

3. The stator assembly of claim 1 wherein wire having a packing density of greater than 80 percent is wound around the poles.

4. The stator assembly of claim 1 wherein the bridges between adjoining segments can be used to orient and position wire relative to the poles.

5. The stator assembly of claim 1 wherein the phase change material has a thermal conductivity of at least 0.4 watts/meter°

K. at 23°

C.

6. The stator assembly of claim 1 wherein the discrete stator segments are each made from a plurality of steel laminations.

7. The stator assembly of claim 1 wherein the phase change material comprises polyamide.

8. The stator assembly of claim 1 wherein the stator segments are held in a torodial shape by a retaining member.

9. The stator assembly of claim 8 wherein the retaining member comprises a metal band.

10. The stator assembly of claim 1 wherein the stator segments are held in a toroidal shape by an overmolded thermoplastic material.

22. The stator assembly of claim 1 where the stator arc segments are at least partially encapsulated in the phase charge material.

25. A motor made from the stator assembly of claim 1.

11. A method of making a stator assembly comprising:

a) providing at least two stator arc segments linked together by a phase change material and each constituting a pole and having a first side surface and a second side surface;

b) winding wire on the poles;

c) aligning said stator arc segments to form a toroidal core, wherein each said side surface of one segment is in contact with an opposing side surface of another segment; and

d) substantially encapsulating said toroidal core with a monolithic body of phase change material to form said stator assembly.

12. The method of claim 11 wherein the phase change material forming the monolithic body has a coefficient of thermal expansion of less than 2×

10<sup>−

5</sup> in/in/°

F. throughout the range of 0-250°

F.

13. The method of claim 11 wherein the phase change material forming the monolithic body has a coefficient of thermal expansion of less than 1.5×

10<sup>−

5</sup> in/in/°

F. throughout the range of 0-250°

F.

14. The method of claim 11 wherein the phase change material forming the monolithic body has a thermal conductivity of at least 0.4 watts/meter°

K. at 23°

C.

15. The method of claim 11 wherein the phase change material is filled with about 30% or more boron nitride.

16. The method of claim 11 wherein the phase change material is filled with about 30% or more aluminum oxide.

17. The method of claim 11 wherein the phase change material linking adjoining segments has a length X, wherein X is the length of uncoiled wire necessary to align said stator arc segments to form said toroidal core.

18. The method of claim 11 wherein said phase change material is selected from the group consisting of thermoplastics and thermosetting materials.

19. The method of claim 11 wherein prior to said substantially encapsulating, said toroidal core is clamped in an injection mold cavity to maintain the toroidal shape.

20. The method of claim 11 wherein said step of substantially encapsulating the core is performed by injection molding said phase change material around said toroidal core.

26. A motor made using a stator assembly made from the method of claim 11.

21. A method of making a stator assembly comprising:

a) providing at least two stator arc segments linked together by a phase change material and each providing a pole and having a first side surface and a second side surface;

b) winding wire on each pole of each arc segment;

c) aligning said stator arc segments to form a toroidal core, wherein each said side surface of one segment is in contact with an opposing side surface of another segment; and

d) placing a retaining member on the exterior of the toroidal core to unitize the structure.

23. The method of claim 21 where the retaining member comprises a metal band.

24. The method of claim 21 wherein each of said stator arc segments comprise a plurality of discrete steel laminations held together by the phase change material.

27. A motor made using a stator assembly made by the method of claim 21.

28. A combination of stator arc segments and a flexible carrier used to link said stator arc segments during a winding operation comprising:

a) a plurality of stator arc segments; and

b) a phase change material constituting said flexible carrier adhered to the stator arc segments which links said segments in a uniform and predetermined position with respect to one another.

29. The combination of claim 28 wherein the stator arc segments each comprise a plurality of steel laminations and wherein the steel laminations are electrically insulated from the wire applied during winding by a portion of the phase change material formed monolithically with the flexible carrier.

30. The combination of claim 29 where the phase change material has a dielectric strength of at least 250 volts per one thousandth of an inch of thickness.

31. A plurality of arc segments for a stator assembly, the arc segments connected to one another by a web of phase change material at least partially encapsulating the stator arc segments.

32. A series of discrete stator segments each substantially encapsulated with, and linked together by bridges made from, an injection molded thermoplastic material.