Patent ID: 8593027
Filing Date: 2013-11-26
Classification: H02K,Y10T

Abstract:
1. A permanent magnet rotor for a brushless electric motor of the kind with an internal stator, the rotor comprising a carrier structure of molded plastic that includes a disc portion to which there is centrally fixed a shaft and whose periphery is joined to an essentially cylindrical cage portion coaxial with the shaft, in which portion there are disposed a magnetic flux conducting structure forming an essentially cylindrical wall which is coaxial with the shaft, and a plurality of permanent magnets shaped as ring segments, disposed at angular intervals within and adjacent to said flux conducting structure; wherein each magnet has its circumferentially terminal faces parallel with each other or converging in the outward direction, the cage portion of the carrier structure is overmolded onto the flux conducting structure and, on an internal surface of the flux conducting structure, forms a plurality of angularly spaced struts which are essentially parallel to the axis of the rotor and which protrude radially inwards; each of the struts having on its flanks respective containment surfaces which are essentially parallel to, or converge in the outward direction with respect to, corresponding containment surfaces of the adjacent struts, such that between the magnetic flux conducting structure and each pair of adjacent struts there is defined a respective seat configured to snugly assemble a respective permanent magnet thereto, and wherein along an axial direction of the shaft, the radial length of the strut becomes greater as it gets closer to the disc portion.