ELECTRIC MACHINE WITH V-RISER COMMUTATOR

1 . A rotor for an electric machine comprising:

a rotor core defining an axis of rotation;

a plurality of windings positioned on the rotor core; and

a commutator extending from the rotor core, the commutator including an elongated contact portion and a riser connected to an end of the elongated contact portion, the riser including a circumferential wall extending radially outward from the end of the elongated contact portion, the circumferential wall including a V-shaped top portion with a plurality of notches formed in the V-shaped top portion.

2 . The rotor of claim 1 , the commutator including an insulative base member and a plurality of separated conductive segments, each conductive segment including an elongated axial portion and a radial portion at the end of the elongated axial portion, the elongated contact portion of the commutator comprising the elongated axial portions and the riser portion of the commutator comprising the radial portions, each of the plurality of notches formed in a central location on the radial portion of each conductive segment.

3 . The rotor of claim 2 wherein an apex of the V-shaped top portion is positioned to a left side and to a right side of each notch and wherein a insulative strip between adjacent conductive segments is positioned adjacent to each apex.

4 . The rotor of claim 3 wherein each V-shaped portion includes a sloped proximate surface and a sloped distal surface, wherein the slope on the proximate surface is between thirty and sixty degrees relative to the axis of rotation.

5 . The rotor of claim 4 wherein the slope on the proximate surface is about forty-five degrees relative to the axis of rotation.

6 . The rotor of claim 3 wherein the sloped proximate surface and the sloped distal surface have substantially the same slope.

7 . The rotor of claim 1 wherein each of the notches extends about 3 mm in the axial direction.

8 . The rotor of claim 1 wherein the commutator further comprises a coupling portion, the riser positioned between the coupling portion and the elongated contact portion.

9 . The rotor of claim 8 wherein the V-shaped top portion includes a sloped proximate surface and a sloped distal surface, the sloped proximate surface closer to the coupling portion than the sloped distal surface, the sloped proximate surface and the sloped proximate surface meeting at an apex on the V-shaped top portion.

10 . The rotor of claim 1 further comprising a brush arrangement in contact with the elongated contact portion.

11 . A commutator for an electric machine comprising:

an insulative base member; and

a plurality of conductive segments circularly arranged at equal intervals around the insulative base member, each of the plurality of conductive segments including an elongated axial portion and a radial portion, each radial portion including a first apex portion, a second apex portion, and a notch formed between the first apex portion and the second apex portion.

12 . The commutator of claim 11 wherein the first apex portion and the second apex portion include a sloped proximate surface and a sloped distal surface, the sloped proximate surface meeting the sloped distal surface at an apex.

13 . The commutator of claim 12 wherein the slope on the sloped proximate surface and the sloped distal surface is between thirty and sixty degrees relative to an axis of rotation.

14 . The rotor of claim 13 wherein the sloped proximate surface and the sloped distal surface have substantially the same slope.

15 . The rotor of claim 11 wherein the notch extends about 3 mm an axial direction.

16 . A method of manufacturing an electric machine comprising:

providing a rotor core including a plurality of armature windings with conductor ends extending from the rotor core, the rotor core defining an axis of rotation;

inserting at least one of the plurality of conductor ends into one of a plurality of notches in a riser of a commutator, the riser including a circumferential wall extending radially outward from an end of an elongated contact portion, the circumferential wall including a V-shaped top portion with a plurality of notches formed in the V-shaped top portion;

placing a brazing material on the at least one of the plurality of conductor ends in the one of the plurality of notches; and

applying a heat source to the melt the brazing material in the slot.

17 . The method of claim 16 further comprising:

removing the heat source from the brazing material; and

rotating the rotor core and the commutator.

18 . The method of claim 16 wherein the brazing material is a silver/copper/phosphorus material.

19 . The method of claim 16 wherein an apex of the V-shaped top portion is positioned to a left side and to a right side of each of the plurality of notches and wherein a joint between adjacent conductive segments is positioned adjacent to each apex.

20 . The method of claim 16 wherein each of the notches extends about 3 mm in the axial direction.