ELECTRIC MOTOR STATOR HOUSING INTERFERENCE GAP REDUCING METHOD AND APPARATUS

• US 20140197701A1
• Filed: 01/17/2013
• Published: 07/17/2014
• Est. Priority Date: 01/17/2013
• Status: Active Grant

• Current Assignee: BorgWarner Incorporated
• Original Assignee: Remy Technologies LLC (BorgWarner Incorporated)
• Inventors: Hossain, Noman, Chamberlin, Bradley D.
• Granted Patent: US 9,246,370 B2
• Time in Patent Office: Days
• US Class Current: 310/52
• CPC Class Codes: H02K 1/185 to outer stators
• CPC Class Codes: H02K 5/203 specially adapted for liquids, e.g. cooling jackets
• CPC Class Codes: H02K 9/19 for machines with closed casing and closed-circuit cooling using a liquid cooling medium, e.g. oil
• CPC Class Codes: H02K 9/223 Heat bridges
• CPC Class Codes: Y10T 29/49009 Dynamoelectric machine

Abstract

A cooling system of an electric machine includes a stator core, a housing, and a thermal interfacial material interposed between complementary mating surfaces of the stator core and the housing for substantially eliminating air gaps therebetween. A method of cooling an electric machine having a housing and a stator includes placing a thermal interfacial material onto a heat transfer interface between the stator and the housing, whereby the thermal interfacial material reduces contact resistance at the heat transfer interface. A method of cooling a stator of an electric machine includes heating a housing having a radially inner surface, coating a radially outer surface of the stator and/or the radially inner surface of the housing with a thermal interfacial material, and inserting the stator into the heated housing, whereby the thermal interfacial material is interposed between the inner surface of the housing and the outer surface of the stator.

Claims

1. A cooling system of an electric machine, comprising:

a stator core;

a housing; and

a thermal interfacial material interposed between complementary mating surfaces of the stator core and the housing for substantially eliminating air gaps therebetween.

2. The cooling system of claim 1, wherein the housing includes a cooling jacket wall, and wherein the thermal interfacial material is interposed between complementary mating surfaces of the stator and the cooling jacket wall.

3. The cooling system of claim 2, further comprising seals at axial ends of the thermal interfacial material for enclosing the material between the complementary mating surfaces.

4. The cooling system of claim 3, wherein the seals include epoxy.

5. The cooling system of claim 3, wherein the enclosed thermal interfacial material comprises liquid.

6. The cooling system of claim 1, wherein the complementary mating surfaces have an interference fit.

7. The cooling system of claim 1, wherein the thermal interfacial material has a nominal thickness between 0.02 mm and 0.5 mm.

8. The cooling system of claim 1, wherein the thermal interfacial material is substantially uncurable thermal grease.

9. The cooling system of claim 1, wherein the respective mating surfaces of the stator core and the housing are substantially annular.

10. A method of cooling an electric machine having a housing and a stator, comprising placing a thermal interfacial material onto a heat transfer interface between the stator and the housing, whereby the thermal interfacial material reduces contact resistance at the heat transfer interface.

11. The method of claim 10, further comprising:

heating and thereby expanding the housing;

cooling and thereby shrinking the stator;

installing the cooled stator within the heated housing; and

cooling the housing so that the stator is interference fit therein.

12. The method of claim 10, wherein the housing comprises a cooling jacket having a radially inner surface that abuts a radially outer surface of the stator to form the heat transfer interface.

13. The method of claim 10, further comprising, prior to the placing of the thermal interfacial material, machining a radially outer surface of the stator to substantially reduce surface irregularities.

14. A method of cooling a stator of an electric machine, comprising:

heating a housing having a radially inner surface;

coating at least one of a radially outer surface of the stator and the radially inner surface of the housing with a thermal interfacial material; and

inserting the stator into the heated housing;

whereby the thermal interfacial material is interposed between the inner surface of the housing and the outer surface of the stator.

15. The method of claim 14, further comprising sealing the stator to the housing, thereby enclosing axial ends of the thermal interfacial material.

16. The method of claim 15, wherein the sealing comprises curing the thermal interfacial material.

17. The method of claim 15, wherein the sealing comprises applying a bead of epoxy.

18. The method of claim 15, wherein the sealing comprises filling a space of the electric machine with potting material.

19. The method of claim 14, further comprising machining the outer surface of the stator to thereby substantially remove surface irregularities.

20. The method of claim 14, wherein the coating includes radially biasing the thermal interfacial material against the surface being coated.