Electric machine having rotor and stator cooling assembly

1. A cooling assembly for an electric machine having a housing, a shaft rotatably supported within the housing, a rotor operatively coupled to rotate with the shaft, and a stator annularly surrounding the rotor, the cooling assembly comprising:

an axial passage formed along a longitudinal axis of the shaft and configured to direct cooling oil from a first end of the shaft towards a second end of the shaft opposite the first end of the shaft;

an angled passage fluidly connected to the axial passage at an oblique angle and configured to redirect the cooling oil towards a gap between an outer surface of a central region of an outer surface of the rotor and an inner surface of the stator; and

an arcuate groove formed along the outer surface of the rotor, the angled passage introduces cooling oil into an apex of the arcuate groove at the central region of the outer surface of the rotor, the arcuate groove extending from a first end of the rotor to a second end of the rotor and configured to sling the cooling oil to the opposing ends of the rotor.

2. The cooling assembly of claim 1 , wherein the angled passage is formed partially within the shaft and partially within the rotor.

3. The cooling assembly of claim 2 , wherein the angled passage extends from a point along the longitudinal axis of the shaft in between the first end of the shaft and a lengthwise center of the shaft to a point along the outer surface of the rotor at a lengthwise center of the rotor.

4. The cooling assembly of claim 2 , wherein the angled passage is formed at an angle of about 30-60° with respect to the longitudinal axis of the shaft.

5. The cooling assembly of claim 2 , wherein the angled passage includes a plurality of angled passages circumferentially spaced apart about the longitudinal axis of the shaft.

6. The cooling assembly of claim 1 , wherein the arcuate groove is formed, such that the cooling oil exits the arcuate groove at an angle of about 20-40° with respect to the longitudinal axis of the shaft.

7. The cooling assembly of claim 1 , wherein the arcuate groove includes a plurality of arcuate grooves circumferentially spaced apart around the outer surface of the rotor.

8. The cooling assembly of claim 1 , further including:

a first radial passage located at the first end of shaft and configured to sling the cooling oil radially outward towards ends of the rotor and the stator proximate the first end of the shaft; and

a second radial passage located at the second end of shaft and configured to sling the cooling oil radially outward towards ends of the rotor and the stator proximate the second end of the shaft.

9. The cooling assembly of claim 8 , wherein the first and second radial passages extend from the longitudinal axis of the shaft to an outer surface of the shaft.

10. The cooling assembly of claim 8 , wherein:

the first radial passage includes a plurality of first radial passages circumferentially spaced apart about the longitudinal axis of the shaft; and

the second radial passage includes a plurality of second radial passages circumferentially spaced apart about the longitudinal axis of the shaft.

11. The cooling assembly of claim 1 , further including an inlet port located at the first end of the shaft and configured to introduce the cooling oil to the axial passage.

12. A cooling assembly for an electric machine having a housing, a shaft rotatably supported within the housing, a rotor operatively coupled to rotate with the shaft, and a stator annularly surrounding the rotor, the cooling assembly comprising:

an axial passage formed along a longitudinal axis of the shaft and configured to direct cooling oil from a first end of the shaft towards a second end of the shaft opposite the first end of the shaft;

a plurality of angled passages fluidly connected to the axial passage at oblique angles and configured to redirect the cooling oil towards a gap between a central region of an outer surface of the rotor and an inner surface of the stator;

a plurality of arcuate grooves formed along the outer surface, the plurality of angled passages introduce cooling oil into an apex of the plurality of arcuate grooves at the central region of the outer surface of the rotor, the plurality of arcuate grooves extending from a first end of the rotor to a second end of the rotor and configured to sling the cooling oil to the opposing ends of the rotor;

a plurality of first radial passages located at the first end of shaft and configured to sling the cooling oil radially outward towards ends of the rotor and the stator proximate the first end of the shaft; and

a plurality of second radial passages located at the second end of shaft and configured to sling the cooling oil radially outward towards ends of the rotor and the stator proximate the second end of the shaft.

13. The cooling assembly of claim 12 , wherein each of the plurality of angled passages is formed partially within the shaft and partially within the rotor.

14. The cooling assembly of claim 13 , wherein each of the plurality of angled passages extends from a point along the longitudinal axis of the shaft in between the first end of the shaft and a lengthwise center of the shaft to a point along the outer surface of the rotor at a lengthwise center of the rotor.

15. The cooling assembly of claim 13 , wherein each of the plurality of angled passages is formed at an angle of about 30-60° with respect to the longitudinal axis of the shaft.

16. The cooling assembly of claim 12 , wherein each of the plurality of arcuate grooves is formed, such that the cooling oil exits the respective arcuate groove at an angle of about 20-40° with respect to the longitudinal axis of the shaft.

17. The cooling assembly of claim 12 , wherein each of the plurality of first and second radial passages extend from the longitudinal axis of the shaft to an outer surface of the shaft.

18. An electric machine, comprising:

a housing;

a shaft rotatably supported within the housing;

a rotor operatively coupled to rotate with the shaft;

a stator annularly surrounding the rotor; and

a cooling assembly including:

an axial passage formed along a longitudinal axis of the shaft and configured to direct cooling oil from a first end of the shaft towards a second end of the shaft opposite the first end of the shaft;

a plurality of angled passages fluidly connected to the axial passage at oblique angles and configured to redirect the cooling oil towards a gap between an outer surface of a central region of the rotor and an inner surface of the stator;

a plurality of arcuate grooves formed along the outer surface, the plurality of angled passages introduce cooling oil into an apex of the plurality of arcuate grooves at the central region of the outer surface of the rotor, the plurality of arcuate grooves extending from a first end of the rotor to a second end of the rotor and configured to sling the cooling oil to the opposing ends of the rotor;

a plurality of first radial passages located at the first end of shaft and configured to sling the cooling oil radially outward towards ends of the rotor and the stator proximate the first end of the shaft; and

a plurality of second radial passages located at the second end of shaft and configured to sling the cooling oil radially outward towards ends of the rotor and the stator proximate the second end of the shaft.