Liquid cooled rotor assembly

• US 20080272661A1
• Filed: 05/01/2007
• Published: 11/06/2008
• Est. Priority Date: 05/01/2007
• Status: Active Grant

• Current Assignee: Tesla Inc.
• Original Assignee: Tesla Motors Incorporated (Tesla Inc.)
• Inventors: Zhou, Peng, Cutler, Grant Dufresne, Kalayjian, Nicholas Robert, Augenbergs, Peteris Koch
• Granted Patent: US 7,489,057 B2
• Time in Patent Office: Days
• US Class Current: 310/61
• CPC Class Codes: H02K 9/197 in which the rotor or stator space is fluid-tight, e.g. to provide for different cooling media for rotor and stator

Abstract

A rotor assembly cooling system (100) and method of using same are provided. A portion of the rotor shaft (103) is hollow, the rotor shaft including an open end (107) and a closed end (105). A coolant feed tube (109) is rigidly attached to the rotor shaft (103) using one or more support members (111), thus causing the shaft and the feed tube to rotate at the same rate. Coolant is pumped through the feed tube until it exits the end of the feed tube and flows against the inside surface of the closed end of the rotor shaft causing the coolant to change direction and flow back through the coolant flow region, this region being defined as the space between the outer surface of the feed tube and the inner surface of the hollow rotor shaft.

Claims

1. An electric motor comprising:

a stator;

a rotor mounted within said stator, said rotor comprised of a shaft, wherein a portion of said shaft is hollow;

a coolant feed tube rigidly attached to said shaft and mounted within said hollow portion of said shaft, wherein a separation between an outer surface of said coolant feed tube and an inner surface of said hollow portion of said shaft defines a coolant flow region; and

means for pumping coolant into said coolant feed tube, wherein said coolant flows through said coolant feed tube in a first direction and flows through said coolant flow region in a second direction.

2. The electric motor of claim 1, said shaft further comprising an open first end and a closed second end, wherein said coolant feed tube passes through said open first end of said shaft, and wherein an inner surface of said closed second end reverses said coolant flow from said first direction to said second direction.

3. An electric motor cooling system comprising:

a rotor shaft, said rotor shaft comprised of an open end, a closed end and a hollow portion between said open end and said closed end;

a coolant feed tube positioned within said hollow portion of said rotor shaft, wherein a separation between an outer surface of said coolant feed tube and an inner surface of said hollow portion of said shaft defines a coolant flow region;

means for rigidly coupling said coolant feed tube to said rotor shaft; and

means for pumping coolant through a closed coolant circuit, said closed coolant circuit comprised of said coolant flowing in a first direction through said coolant feed tube, said coolant reversing direction at said closed end of said rotor shaft, and said coolant flowing in a second direction through said coolant flow region.

4. The electric motor cooling system of claim 3, wherein said pumping means is comprised of a coolant pump.

5. The electric motor cooling system of claim 3, wherein said means for rigidly coupling said coolant feed tube to said rotor shaft further comprises a plurality of support members.

6. The electric motor cooling system of claim 5, wherein each of said plurality of support members is comprised of a plurality of spokes.

7. The electric motor cooling system of claim 5, wherein each of said plurality of support members is comprised of a first ring proximate to and attached to said outer surface of said coolant feed tube, a second ring proximate to and attached to said inner surface of said hollow portion of said shaft, and a plurality of spokes rigidly coupling said first ring to said second ring.

8. The electric motor cooling system of claim 5, wherein each of said plurality of support members is comprised of a ring, wherein an inner edge of said ring is proximate to and attached to said outer surface of said coolant feed tube and wherein an outer edge of said ring is proximate to and attached to said inner surface of said hollow portion of said shaft, and wherein said ring is further comprised of a plurality of holes passing from a first side of said ring to a second side of said ring.

9. The electric motor cooling system of claim 8, wherein each of said plurality of holes is angled.

10. The electric motor cooling system of claim 5, wherein each of said plurality of support members is comprised of a ring, wherein an inner edge of said ring is proximate to and attached to said outer surface of said coolant feed tube and wherein an outer edge of said ring is proximate to and attached to said inner surface of said hollow portion of said shaft, and wherein said ring is further comprised of a plurality of slots passing from a first side of said ring to a second side of said ring.

11. The electric motor cooling system of claim 10, wherein each of said plurality of slots is angled.

12. The electric motor cooling system of claim 3, wherein said means for rigidly coupling said coolant feed tube to said rotor shaft further comprises a continuous support strut, said continuous support strut helically wrapped around and attached to said coolant feed tube, wherein an outer edge of said continuous support strut is proximate to and attached to said inner surface of said hollow portion of said shaft.

13. The electric motor cooling system of claim 3, wherein an inner surface of said closed end of said rotor shaft is shaped.

14. The electric motor cooling system of claim 3, wherein an inner surface of said closed end of said rotor shaft has a non-planar shape to promote said coolant reversing direction at said closed end of said rotor shaft.

15. A method of cooling an electric motor in an electric vehicle, said method comprising of the steps of:

rotating a rotor shaft of the electric motor at a shaft rotation rate;

rotating a coolant feed tube mounted within a hollow portion of said rotor shaft at a tube rotation rate, wherein said tube rotation rate is equivalent to said shaft rotation rate;

pumping a coolant in a first direction through said coolant feed tube; and

flowing said coolant in a second direction through a coolant flow region between an outer surface of said coolant feed tube and an inner surface of said hollow portion of said rotor shaft.

16. The method of claim 15, wherein said first direction is opposite said second direction.

17. The method of claim 15, further comprising the step of rigidly attaching said coolant feed tube to said hollow portion of said rotor shaft with a plurality of support members.

18. The method of claim 15, further comprising the step of rigidly attaching said coolant feed tube to said hollow portion of said rotor shaft with a continuous support strut helically wrapped around said coolant feed tube.

19. The method of claim 15, further comprising the step of redirecting said coolant from said first direction to said second direction, said redirecting step further comprising the step of pumping said coolant against an inner surface of a closed end of said rotor shaft.