ELECTRIC MOTOR AND METHOD OF COOLING

• US 20120104884A1
• Filed: 11/01/2011
• Published: 05/03/2012
• Est. Priority Date: 11/01/2010
• Status: Active Grant

• Current Assignee: Mission Motor Company (Vayon Holdings Ltd.)
• Original Assignee: Mission Motor Company (Vayon Holdings Ltd.)
• Inventors: WAGNER, JON, SHERWOOD, MARK, KARPLUS, PAUL
• Granted Patent: US 8,970,074 B2
• Time in Patent Office: Days
• US Class Current: 310/54
• CPC Class Codes: H02K 1/32 with channels or ducts for flow of cooling medium
• CPC Class Codes: H02K 5/203 specially adapted for liquids, e.g. cooling jackets
• CPC Class Codes: H02K 7/003 Couplings; Details of shafts means for mounting rotors on shafts H02K1/28
• CPC Class Codes: H02K 9/19 for machines with closed casing and closed-circuit cooling using a liquid cooling medium, e.g. oil

Abstract

A system for cooling an electric motor, the electric motor including a stator disposed about a rotor, wherein cooling system includes a rotor assembly including a shaft with a shaft channel extending through the center of the shaft and radial channels extending radially from the shaft channel; a rotor with profiled rotor ends; and two guides, each coupled to a rotor end, that guides fluid from the shaft exterior to the rotor end. The system may additionally include interior channels that traverse through the rotor interior, wherein the interior channels fluidly couple the radial channels to a guide-rotor end pair. The system may also include stator cooling mechanisms, including cooling channels within the motor casing proximal to stator exterior surface and dispensing mechanisms that dispense working fluid to the stator coils.

Claims

1. A system for cooling an electric motor comprising:

a stator comprising stator coils;

a rotor assembly arranged within the stator, the rotor assembly comprising;

a shaft comprising;

a shaft channel extending coaxially through a portion of the shaft that is configured to receive a working fluid; and

a radial channel extending radially from the shaft channel that is configured to channel the working fluid from the shaft channel to the shaft exterior;

a rotor, rigidly coupled about the shaft, the rotor having a profiled rotor end that is configured to disperse working fluid from the shaft to the adjacent stator coils; and

a guide, extending from the shaft and arranged proximal the rotor end, that is configured to guide the working fluid against the rotor end.

2. The system of claim 1, wherein the shaft further includes an inlet fluidly coupled to the shaft channel.

3. The system of claim 2, wherein the inlet is an extension of the shaft channel through the shaft end.

4. The system of claim 2, wherein the electric motor further includes a cover that encapsulates the stator, wherein the cover includes a fluid flow path fluidly coupled to the inlet.

5. The system of claim 4, wherein the fluid flow path includes a fluid dispenser configured to dispense the working fluid on the stator coil surface distal the rotor.

6. The system of claim 5, wherein the fluid dispenser is a spray jet.

7. The system of claim 4, wherein the fluid flow path traces a portion of the stator radial surface.

8. The system of claim 7, wherein the fluid flow path is defined between the motor casing and the stator surface, such that the working fluid directly contacts the stator.

9. The system of claim 7, wherein the fluid flow path comprises a plurality of nested boustrophedonic channels terminating in a common inlet and outlet manifold, wherein the outlet manifold is fluidly coupled to the inlet.

10. The system of claim 1, further including an interior channel, extending along a portion of the rotor interior, that is configured to receive the working fluid from the radial channel and to direct the working fluid to the rotor end.

11. The system of claim 10, wherein the interior channel is defined between the shaft and the rotor.

12. The system of claim 1, wherein the shaft includes a plurality of radial channels arranged substantially evenly about the shaft circumference.

13. The system of claim 12, wherein the radial channels exit the shaft substantially near the rotor ends.

14. The system of claim 12, wherein the radial channels exit the shaft at a point substantially centered between the rotor ends.

15. The system of claim 14, wherein each radial channel is offset from another radial channel.

16. The system of claim 1, wherein the rotor end is profiled as an ogee, with a substantially flat inner radial portion transitioning into an overhanging convex outer radial portion, wherein the guide is nested underneath the outer radial portion.

17. The system of claim 16, wherein the guide is concave towards the rotor end.

18. The system of claim 17, wherein the angle of the guide edge proximal the rotor end and distal the shaft is acute.

19. The system of claim 16, wherein the inner radial portion is formed from a rotor steel end, and the outer radial portion is formed from a rotor winding end-piece.

20. The system of claim 15, wherein the system further includes a liquid collector configured to collect working fluid runoff.

21. A method of cooling an electric motor, the motor comprising a rotor assembly comprising a rotor rigidly coupled to a shaft;

the rotor comprising rotor windings terminating in two end-pieces and encircling a piece of rotor steel, the shaft comprising a shaft channel; and

a stator, with stator coils, disposed about the rotor assembly;

the method comprising the steps of;

a) cooling the rotor assembly interior with a working fluid;

b) directing the working fluid from the rotor assembly interior to a rotor end; and

c) dispersing the working fluid from the rotor end to the adjacent stator coils, wherein the rotor end is profiled to facilitate working fluid dispersion.

22. The method of claim 21, wherein step a) comprises the step of channeling the working fluid through the shaft channel.

23. The method of claim 22, wherein step a) further comprises the step of channeling the working fluid along the rotor interior.

24. The method of claim 23, wherein the step of channeling the working fluid along the rotor interior comprises the step of channeling the working fluid through a channel defined between the rotor and the shaft.

25. The method of claim 21, wherein step b) comprises the step of directing the working fluid flowing out of the rotor assembly interior against a rotor end by a guide.

26. The method of claim 21, wherein step c) comprises the sub-steps of:

drawing the working fluid up the rotor steel end by leveraging centrifugal force generated by rotor operation;

drawing the working fluid up the end-piece by leveraging the centrifugal force and the Coanda effect; and

dispersing the working fluid from the end-piece onto adjacent stator coils as the Coanda effect on the working fluid lessens;

wherein the end-piece overhangs the rotor steel end to form a profiled rotor end.

27. The method of claim 21, further including step d) cooling the stator coils distal the rotor with the working fluid.

28. The method of claim 27, wherein step d) occurs before step a), such that the working fluid cools the stator coils before flowing to the rotor assembly.

29. The method of claim 27, wherein step d) comprises the step of spraying a portion of the working fluid onto the stator coils.

30. The method of claim 27, wherein step d) comprises the step of flowing the working fluid through channels defined in a portion of the motor casing proximal the stator coils.

31. The method of claim 30, wherein the channels are defined between the motor casing and the stator coils.

32. The method of claim 30, wherein step d) further comprises the step of spraying a portion of the working fluid onto the stator coil ends.

33. The method of claim 32, wherein the channels terminate in a common inlet and a common outlet manifold, wherein the working fluid is sprayed from the inlet and outlet manifolds.