Rotor including anti-rotation feature for multi-pole structure

1. A permanently magnetizable rotor having a central rotor structure including a rotor shaft supporting a cylindrical backiron, the rotor further including a multi-pole structure comprising circumferentially alternating pole elements, and a rotor cover extending longitudinally over the multi-pole structure, the rotor further comprising:

an endcap including an engagement surface positioned in engagement with an end of the backiron, the endcap defining first and second anti-rotation features for preventing circumferential rotation of one or more of the pole elements about the backiron;

wherein the first anti-rotation feature is configured differently than the second anti-rotation feature and each anti-rotation feature defines a torque transmitting feature for transmitting a torque from different locations on the multi-pole structure; and

wherein the endcap includes a peripheral surface, and the first anti-rotation feature comprises discrete indentations extending into the peripheral surface alternating circumferentially along the peripheral surface with non-indented portions, and engaged by a plurality of circumferentially spaced corresponding discrete portions of an end of the rotor cover that extend in a radial direction inwardly past the non-indented portions of the peripheral surface of the endcap.

2. The rotor of claim 1 , wherein the rotor cover comprises a thin metal member that is formed into the discrete indentations of the first anti-rotation feature and is further formed to conform around radially extending contours on the multi-pole structure.

3. The rotor of claim 1 , wherein the second anti-rotation feature comprises tabs that extend axially from the engagement surface of the endcap and engage in spaces defined in at least an end portion of the multi-pole structure.

4. The rotor of claim 3 , wherein the tabs have a radially facing outer surface, and the outer surface is located aligned with a circumferential outer edge of the endcap.

5. The rotor of claim 4 , wherein the tabs define a triangular cross-section, including two sides that taper toward each other in a radially inward direction toward a center of the endcap.

6. The rotor of claim 4 , wherein the multi-pole structure has a length dimension in the axial direction, and the tabs have a length in the axial direction that is less than the length of the multi-pole structure.

7. The rotor of claim 1 , including an interengagement structure comprising an element of the endcap having a predetermined shape and a cooperating element on the central rotor structure having a complementary shape preventing relative rotation between the endcap and the central rotor structure, and wherein:

the second anti-rotation feature comprises tabs that extend axially from the engagement surface of the endcap and engage in spaces defined in at least an end portion of the multi-pole structure.

8. The rotor of claim 7 , wherein the pole elements comprise separate elements, each pole element including a radially inner side that is adhesively affixed to the backiron.

9. The rotor of claim 7 , wherein the interengagement structure comprises endcap posts extending from the engagement surface into the backiron and preventing relative rotation between the endcap and the backiron.

10. A permanently magnetizable rotor having a central rotor structure including a rotor shaft supporting a cylindrical backiron, the rotor further including a multi-pole structure comprising circumferentially alternating pole elements and spaces that extend generally longitudinally between adjacent pole elements, and a rotor cover extending longitudinally over the multi-pole structure, the rotor further comprising:

an endcap including:

an engagement surface positioned in engagement with an end of the backiron;

a peripheral surface located at a circumferential edge of the endcap;

an interengagement structure comprising an element of the endcap having a predetermined shape and a cooperating element on the central rotor structure having a complementary shape preventing relative rotation between the endcap and the central rotor structure; and

an anti-rotation feature for preventing circumferential rotation of one or more of the pole elements about the backiron, the anti-rotation feature comprising discrete indentations extending into the peripheral surface alternating circumferentially along the peripheral surface with non-indented portions, and engaged by a plurality of circumferentially spaced corresponding discrete portions of an end of the rotor cover that extend in a radial direction inwardly past the non-indented portions of the peripheral surface of the endcap for transmitting a torque from a location of the spaces between adjacent pole elements to circumferential locations along the circumference of the endcap.

11. The rotor of claim 10 , wherein the rotor cover comprises a thin metal member that is formed into the discrete indentations of the anti-rotation feature.

12. The rotor of claim 11 , wherein the pole elements each include a pair of longitudinally extending edges, wherein the spaces are defined between longitudinal edges of adjacent pole elements, and the rotor cover is further formed into at least a portion of the spaces between the longitudinal edges of the pole elements.

13. The rotor of claim 10 , including an additional anti-rotation feature comprising tabs that extend axially from the engagement surface of the endcap and engage in the spaces between adjacent pole elements.

14. A permanently magnetizable rotor having a central rotor structure including a rotor shaft supporting a cylindrical backiron, the rotor further including a multi-pole structure comprising circumferentially alternating pole elements, the rotor further comprising:

an endcap including:

an engagement surface positioned in engagement with an end of the backiron;

an interengagement structure comprising an element of the endcap having a predetermined shape and a cooperating element on the central rotor structure having a complementary shape preventing relative rotation between the endcap and the central rotor structure;

an anti-rotation feature for preventing circumferential rotation of one or more of the pole elements about the backiron, the anti-rotation feature comprising tabs that extend axially from the engagement surface of the endcap and engage in spaces defined in at least an end portion of the multi-pole structure for transmitting a torque from a location on a longitudinal end of the multi-pole structure to circumferential locations along the circumference of the endcap;

a rotor cover extending longitudinally over the multi-pole structure and engaging in spaces between adjacent pole elements; and

an additional anti-rotation feature comprising discrete indentations extending into a peripheral surface of the endcap alternating circumferentially along the peripheral surface with non-indented portions, and engaged by a plurality of circumferentially spaced corresponding discrete portions of an end of the rotor cover that extend in a radial direction inwardly past the non-indented portions of the peripheral surface of the endcap.

15. The rotor of claim 14 , wherein the tabs have a radially facing outer surface, and the outer surface is located aligned with a circumferential outer edge of the endcap.

16. The rotor of claim 14 , wherein the tabs define a triangular cross-section, including two sides that taper toward each other in a radially inward direction toward a center of the endcap.

17. The rotor of claim 14 , wherein the multi-pole structure has a length dimension in the axial direction, and the tabs have a length in the axial direction that is less than the length of the multi-pole structure.