Patent ID: 8395293

Claim:
A permanent magnet rotor for a brushless electric motor of the kind having an internal stator, the rotor comprising a supporting structure made of molded plastic that includes an essentially disc-shaped portion to which a shaft is centrally connected, and the periphery of which is joined to an essentially cylindrical cage portion which extends coaxially around the shaft and in which there are disposed a plurality of yokes made of a magnetically conducting material and shaped as ring segments which as a whole form an essentially cylindrical wall, and a plurality of permanent magnets, likewise shaped as ring segments, respectively disposed astride the junction of a pair of adjacent yokes, wherein each yoke has a dimension which increases from the circumferential ends thereof towards its circumferentially intermediate portion, such that the cross-sectional area of the yoke in a radial plane correspondingly increases from the ends thereof towards its intermediate portion.