Retention cap for permanent magnet rotor

Patent metadata

Field	Value
Publication number	US-12255497-B2
Application number	US-202218051347-A
Country	US
Kind code	B2
Filing date	Oct 31, 2022
Priority date	Nov 3, 2021
Publication date	Mar 18, 2025
Grant date	Mar 18, 2025

Abstract

A rotor for an electric motor includes a core, a plurality of magnets, and a magnet retention cap. The core is rotatable about an axis and defines a plurality of magnet-receiving slots. Each of the magnets is received in a respective one of the magnet-receiving slots. The magnet retention cap is fixed relative to the core and includes a resiliently deformable magnet retention element configured to restrict axial movement of the magnets relative to the core.

First claim

What is claimed is:

1. A rotor for an electric motor, said rotor comprising:
a core rotatable about an axis and defining a plurality of magnet-receiving slots;
a plurality of magnets, each of said magnets being received in a respective one of said magnet-receiving slots; and
a magnet retention cap fixed relative to said core and including a resiliently deformable magnet retention element configured to restrict axial movement of the magnets relative to the core,
said magnet retention element including a plurality of resiliently deflectable fingers,
each of said fingers corresponding to one of said magnets,
said cap further including a body,
each of said fingers extending from said body in a cantilevered manner,
each of said fingers including a base extending from the body and a tip spaced from the base,
said base being broader than said tip such that said finger tapers from the base to the tip.

2. The rotor of claim 1 ,
said base presenting a base width,
said tip presenting a tip width,
said base width being at least one and one half times said tip width.

3. The rotor of claim 1 ,
said body defining a plurality of slots,
each of said fingers extending into a corresponding one of said slots.

4. The rotor of claim 1 ,
said body being spaced from the core and the magnets.

5. A rotor for an electric motor, said rotor comprising:
a core rotatable about an axis and defining a plurality of magnet-receiving slots;
a plurality of magnets, each of said magnets being received in a respective one of said magnet-receiving slots; and
a magnet retention cap fixed relative to said core and including a resiliently deformable magnet retention element configured to restrict axial movement of the magnets relative to the core,
said magnet retention element including a plurality of resiliently deflectable fingers,
each of said fingers corresponding to one of said magnets,
said cap further including a body,
each of said fingers extending from said body in a cantilevered manner,
each of said fingers including a main form and a nub extending from the main form,
said main form being spaced from the corresponding one of the magnets and including a base extending from the body and a tip spaced from the base,
said nub configured to engage a corresponding one of the magnets.

6. The rotor of claim 5 ,
said nub extending from said main form adjacent the tip.

7. The rotor of claim 5 ,
said body being spaced from the core and the magnets.

8. The rotor of claim 7 ,
said cap including a boss extending from the body and engaging the core.

9. A rotor for an electric motor, said rotor comprising:
a core rotatable about an axis and defining a plurality of magnet-receiving slots;
a plurality of magnets, each of said magnets being received in a respective one of said magnet-receiving slots; and
a magnet retention cap fixed relative to said core and including a resiliently deformable magnet retention element configured to restrict axial movement of the magnets relative to the core,
said cap further including a body,
said magnet retention element extending from said body,
said body being spaced from the core and the magnets,
said cap including a boss extending from the body and engaging the core,
said cap including a plurality of said bosses,
said bosses being arcuately spaced apart along the body and each engaging the core.

10. The rotor of claim 9 , said magnet retention element including a plurality of resiliently deflectable fingers, each of said fingers corresponding to one of said magnets.

11. The rotor of claim 10 ,
each of said fingers extending from said body in a cantilevered manner.

12. The rotor of claim 9 ,
one of said core and said cap defining an axially extending opening,
the other of said core and said cap defining an alignment element projecting into said opening to orient the cap relative to the core.

13. A rotor for an electric motor, said rotor comprising:
a core rotatable about an axis and defining a plurality of magnet-receiving slots;
a plurality of magnets, each of said magnets being received in a respective one of said magnet-receiving slots; and
a magnet retention cap fixed relative to said core and including a resiliently deformable magnet retention element configured to restrict axial movement of the magnets relative to the core,
said cap further including a body and a boss extending from the body,
said boss defining an aperture; and
a fastener extending through said aperture and into the core to secure the cap to the core and the boss against the core.

14. The rotor of claim 13 ,
said magnet retention element including a plurality of resiliently deflectable fingers,
each of said fingers corresponding to one of said magnets.

15. A rotor for an electric motor, said rotor comprising:
a core rotatable about an axis and defining a plurality of magnet-receiving slots;
a plurality of magnets, each of said magnets being received in a respective one of said magnet-receiving slots; and
a magnet retention cap fixed relative to said core and including a resiliently deformable magnet retention element configured to restrict axial movement of the magnets relative to the core,
said cap including a radially and circumferentially extending body and a circumferentially extending wall projecting from the body axially away from the core,
said wall having an axial wall height and presenting a contoured form such that the wall height varies circumferentially between maximum and minimum wall heights.

16. The rotor of claim 15 ,
said cap further including a second circumferentially extending wall projecting from the body axially away from the core,
said second wall being spaced radially from the first-mentioned wall,
said second wall having an axial second wall height and presenting a contoured form such that the second wall height varies circumferentially between maximum and minimum second wall heights, in correspondence with variations in the first-mentioned wall height.

17. The rotor of claim 15 ,
said rotor including a fastener extending through the body and into the core to secure the cap to the core,
said wall height being the maximum height adjacent the fastener.

18. The rotor of claim 17 ,
said rotor including exactly two of said fasteners,
each of said fasteners extending through the body and into the core,
said fasteners being diametrically opposed,
said wall height being the maximum height adjacent each of the fasteners.

19. The rotor of claim 17 ,
said cap further including a boss extending from the body and engaging the core such that the body is spaced from the core and the magnets,
said boss defining an aperture,
said fastener extending through said aperture and into the core to secure the cap to the core and the boss against the core.

20. The rotor of claim 15 ,
said magnet retention element including a plurality of resiliently deflectable fingers,
each of said fingers corresponding to one of said magnets.

Assignees

• Nidec Motor Corp

Inventors

• Corcoran Marc J
• Sherman Jeffrey Scott
• Bailey Daniel E
• Modi Chetan O
• Hussey John H

Classifications

• H02K1/2773

  consisting of tangentially magnetized radial magnets · CPC title

• H02K1/28 Primary

  Means for mounting or fastening rotating magnetic parts on to, or to, the rotor structures · CPC title