Arrangement for cooling an electric machine with a layer of thermally conducting and electrically insulating material

• US 9,559,569 B2
• Filed: 02/13/2012
• Issued: 01/31/2017
• Est. Priority Date: 02/13/2012
• Status: Active Grant

• Current Assignee: GE Aviation Systems LLC (GE Aerospace)
• Original Assignee: GE Aviation Systems LLC (GE Aerospace)
• Inventors: Huang, Hao, Jia, Xiaochuan, Wirsch, Paul James Jr.
• Primary Examiner(s): GONZALEZ QUINONES, JOSE A
• Application Number:
  US13/371,657
• Publication Number:
  US 20130207395A1
• Time in Patent Office: 1,814 Days
• Field of Search: 310/58, 310/198, 310201-203, 310/206, 310/215, 310/260, 310/270
• US Class Current: 1/1
• CPC Class Codes: H02K 2213/03 Machines characterised by numerical values, ranges, mathematical expressions or similar information
• CPC Class Codes: H02K 3/24 with channels or ducts for cooling medium between the conductors
• CPC Class Codes: H02K 3/30 Windings characterised by the insulating material
• CPC Class Codes: H02K 3/325 for windings on salient poles, such as claw-shaped poles
• CPC Class Codes: H02K 3/38 around winding heads, equalising connectors, or connections thereto
• CPC Class Codes: H02K 5/203 specially adapted for liquids, e.g. cooling jackets
• CPC Class Codes: H02K 9/227 Heat sinks

Abstract

An assembly for a gas turbine engine includes a S/G having a rotatable shaft, a main machine, a PMG, and an exciter wherein at least one of the main machine, PMG, and exciter includes a rotor mounted to the shaft and having multiple rotor poles, a stator having multiple stator poles and at least one of the rotor poles and stator poles being formed by a core with a post and wire wound about the post to form a winding, with the winding having at least one end turn, and a layer to increase cooling capabilities of a portion of at least one of the stator and the rotor.

Claims

1. An electric machine comprising:

a rotor having a set of rotor poles;

a stator having a set of stator poles;

at least one rotor pole in the set of rotor poles being formed by a rotor core with a post and wire wound about the post to form a rotor winding, with the rotor winding having at least one end turn;

at least one stator pole in the set of stator poles being formed by a stator core with a post and wire wound about the post to form a stator winding, with the stator winding having at least one end turn;

a liquid cooling conduit passing through the at least one rotor core, proximate to the at least one winding;

a layer of thermally conducting and electrically insulating material encircling the rotor winding and provided between a thermally conductive cooling fin and the rotor winding, and the thermally conductive cooling fin encircling the insulating material and provided between the insulating material and the conduit,

wherein the insulating material abuts both the rotor winding and the thermally conductive cooling fin to increase the thermal conduction from the rotor winding to the liquid cooling conduit whereby liquid coolant passing through the liquid cooling conduit will dissipate heat from the rotor winding, and the thermally conductive cooling fin is mounted to a portion of the liquid cooling conduit, and the layer of thermally conducting and electrically insulating material has a conductivity equal to or greater than about 0.75 W/mC;

a cooling system having at least one cooling passage passing through a jacket surrounding the stator core;

at least one coil support mounted between the cooling passage and the at least one end turn of the stator core, wherein the coil support is conform-coated with a layer of thermally conducting and electrically insulating material to exchange heat from the end turn through the coil support to the cooling passage without wetting the stator winding.

2. The electric machine of claim 1 wherein there are multiple end turns and the layer of thermally conducting and electrically insulating material is provided between each of the end turns of stator winding and the at least one coil support.

3. The electric machine of claim 2 wherein there are multiple windings, with each winding having at least one end turn to form the multiple end turns.

4. The electric machine of claim 3 wherein each of the multiple windings has multiple end turns.

5. The electric machine of claim 4 wherein the layer comprises a mixture including boron nitride.

6. The electric machine of claim 1 wherein the layer has a minimum dielectric strength of 250 V/mil.

7. The electric machine of claim 1 wherein the layer comprises boron nitride.

8. The electric machine of claim 7 wherein the layer comprises a mixture including boron nitride.

9. The electric machine of claim 8 wherein the winding is coated with the mixture.

10. The electric machine of claim 1 wherein the rotor further comprises a rotatable shaft.

11. The electric machine of claim 10 wherein the stator defines an interior through which the rotatable shaft extends.

12. The electric machine of claim 1 wherein the electric machine is one of a main machine, an exciter, and a permanent magnet generator.

13. An assembly for a gas turbine engine comprising:

an accessory gearbox;

a starter/generator mechanically mounted to the accessory gearbox, comprising;

a rotatable shaft;

a main machine carried by the shaft;

a permanent magnet generator (PMG) carried by the shaft;

an exciter carried by the shaft;

wherein at least one of the main machine, PMG, and exciter comprises;

a rotor mounted to the shaft and having at least one rotor pole, and

a stator having at least one stator pole,

the at least one rotor pole being formed by a rotor core with a post and wire wound about the post to form a rotor winding, with the rotor winding having at least one end turn, and

the stator pole being formed by a stator core with a post and wire wound about the post to form a stator winding, with the stator winding having at least one end turn;

a liquid cooling conduit passing through the rotor core, proximate to the winding;

a layer of thermally conducting and electrically insulating material encircling the rotor winding and provided between a thermally conductive cooling fin and the winding, the thermally conductive cooling fin encircling the insulating material and provided between the insulating material and the conduit;

wherein the insulating material abuts both the rotor winding and the thermally conductive cooling fin to increase the thermal conduction from the rotor winding to the liquid cooling conduit whereby liquid coolant passing through the liquid cooling conduit will dissipate heat from the rotor winding, the thermally conductive cooling fin is mounted to a portion of the liquid cooling conduit, and the layer of thermally conducting and electrically insulating material has a conductivity equal to or greater than about 0.75 W/mC;

a cooling system having at least one cooling passage through a jacket surrounding the stator core;

at least one coil support mounted between the cooling passage and the at least one end turn of the stator core, wherein the coil support is conform-coated with a layer of thermally conducting and electrically insulating material to exchange heat from the end turn through the coil support to the cooling passage without wetting the stator winding.

14. The assembly of claim 13 wherein the layer has a minimum dielectric strength of 250 V/mil.

15. The assembly of claim 14 wherein the layer comprises boron nitride.