Rotor assembly and method for motor end winding cooling and bearing lubrication

1. A rotor/stator assembly for a motor, comprising:

a rotor shaft comprising a first internal channel;

a rotor core surrounding the rotor shaft;

end windings disposed adjacent to an end of the rotor shaft and an end of the rotor core;

a first end ring abutting a first end of the rotor core and surrounding the rotor shaft; and

a second end ring including an annular structure abutting a second end of the rotor core and surrounding the rotor shaft;

wherein the rotor shaft further comprises a first passage perpendicular to a rotor axis of the rotor shaft and passing through a wall of the rotor shaft at the end thereof, thereby forming a first path by which a cooling fluid is configured to pass from the first internal channel of the rotor shaft to the rotor core and to the end windings in response to a rotation of the rotor shaft; and

wherein the rotor shaft further comprises a second passage aligned non-perpendicular to the rotor axis and defines a second path passing through the wall of the rotor shaft axially beyond the first end ring or axially beyond the second end ring such that the end of the first internal channel is in fluid communication with the end windings in response to the rotation of the rotor shaft.

2. The rotor/stator assembly of claim 1 , wherein the end windings comprise:

a plurality of crown end windings disposed adjacent to the first end of the rotor core; and

a plurality of weld end windings disposed adjacent to the second end of the rotor core opposite from the first end.

3. The rotor/stator assembly of claim 1 , wherein the second passage is circumferentially offset from the first passage about the rotor shaft at the end thereof.

4. The rotor/stator assembly of claim 1 , wherein the first passage and the second passage define radially-arranged passages passing through the wall of the rotor shaft.

5. The rotor/stator assembly of claim 1 , wherein:

the first passage comprises a relatively smaller cross-sectional diameter, and

the second passage comprises a relatively larger cross-sectional diameter, thereby balancing flow of the cooling fluid through the first passage and the second passage in response to the cooling fluid being pumped into the first internal channel of the rotor shaft.

6. The rotor/stator assembly of claim 1 , wherein:

the rotor core comprises a second internal channel,

the first end ring comprising an outlet port,

the cooling fluid is configured to pass, via the second internal channel and the outlet port, from the first internal channel of the rotor shaft to the rotor core and to the end windings.

7. A motor assembly for a vehicle, comprising:

a rotor/stator assembly, comprising:

a rotor shaft comprising:

an internal channel,

a wall,

a first passage extending from the internal channel and passing through the wall, and

a second passage extending from the internal channel passing through the wall, the second passage circumferentially offset with respect to the first passage;

a rotor core disposed adjacent to the rotor shaft;

end windings disposed adjacent to an end of the rotor shaft and an end of the rotor core;

a first end ring abutting a first end of the rotor core and surrounding the rotor shaft; and

a second end ring abutting a second end of the rotor core and surrounding the rotor shaft;

wherein the first passage forms a first path by which a cooling fluid is configured to pass from the internal channel of the rotor shaft to the end of the rotor core and the end windings in response to rotation of the rotor shaft is rotated; and

wherein the second passage is aligned non-perpendicular to a rotor axis and defines a passage outlet in a radially exterior surface of the wall of the rotor shaft axially beyond the first end ring or axially beyond the second end ring such that the end of the internal channel of the rotor shaft is in fluid communication with the end windings in response to the rotation of the rotor shaft is rotated, as well as in fluid communication with a bearing disposed adjacent to the rotor core.

8. The motor assembly of claim 7 , wherein the end windings comprise:

a plurality of crown end windings disposed adjacent to the first end of the rotor core; and

a plurality of weld end windings disposed adjacent to the second end of the rotor core opposite from the first end.

9. The motor assembly of claim 8 , wherein the first passage is angled in a direction opposite a direction of the second passage.

10. The motor assembly of claim 7 , wherein the rotor shaft further comprises an additional passage that is aligned perpendicular to the rotor axis such that the cooling fluid passes from the internal channel of the rotor shaft to the end windings when the rotor shaft is rotated, wherein the second passage is circumferentially offset from the first passage by 90 degrees about the rotor shaft at the end thereof.

11. The motor assembly of claim 7 , wherein the first passage and the second passage define radially-arranged passages passing through the wall of the rotor shaft.

12. The motor assembly of claim 7 , wherein:

the first passage comprises a relatively smaller cross-sectional diameter, and

the second passage comprises a relatively larger cross-sectional diameter, thereby balancing flow of the cooling fluid through the first passage and the second passage in response to the cooling fluid being pumped into the internal channel of the rotor shaft.

13. The motor assembly of claim 7 , further comprising a heat exchanger, a pump, a filter, and a cooling fluid inlet tube coupled to the rotor shaft and the internal channel thereof.

14. The motor assembly of claim 13 , further comprising a cooling fluid sump coupled to the end windings, the cooling fluid sump adapted to collect the cooling fluid from the rotor shaft and the rotor core and recirculate the cooling fluid to the heat exchanger.

15. A method for cooling a rotor/stator assembly for a motor, comprising:

providing a rotor shaft comprising an internal channel and a non-perpendicular passage;

providing a rotor core disposed adjacent to the rotor shaft;

providing end windings disposed adjacent to an end of the rotor shaft and an end of the rotor core;

providing a first end ring abutting a first end of the rotor core and surrounding the rotor shaft;

providing a second end ring including an annular structure abutting a second end of the rotor core and surrounding the rotor shaft; and

rotating the rotor shaft and the rotor core and pumping, based on rotating the rotor shaft, a cooling fluid into the internal channel of the rotor shaft;

wherein the non-perpendicular passage passes through a wall of the rotor shaft at the end thereof, thereby forming a path aligned with the end windings and a bearing and by which the cooling fluid is configured to pass from the internal channel of the rotor shaft to the end of the rotor core and the end windings and to the bearing in response to a rotation of the rotor shaft.

16. The method of claim 15 , wherein the end windings comprise:

a plurality of crown end windings disposed adjacent to the first end of the rotor core; and

a plurality of weld end windings disposed adjacent to the second end of the rotor core opposite from the first end.

17. The method of claim 15 , further comprising a perpendicular passage, wherein the non-perpendicular passage is circumferentially offset from the perpendicular passage about the rotor shaft at the end thereof.

18. The method of claim 17 , wherein the perpendicular passage and the non-perpendicular passage define radially-arranged passages passing through the wall of the rotor shaft.

19. The method of claim 17 , wherein the perpendicular passage is angled in a direction opposite a direction of the non-perpendicular passage.

20. The method of claim 15 , wherein:

the perpendicular passage comprises a relatively smaller cross-sectional diameter, and

the non-perpendicular passage comprises a relatively larger cross-sectional diameter, thereby balancing the cooling fluid flowing through the perpendicular passage and the non-perpendicular passage in response to the cooling fluid being pumped into the internal channel of the rotor shaft.