Patent ID: 8146234

Claim:
A method for obtaining a permanent-magnet rotor for a synchronous motor comprising an external stator, a cylindrical central core defining an axis X-X and having an axial passage extending along said axis X-X, surrounded by a plurality of permanent magnets having an extrados and an intrados and side edges, wherein the method comprises the following steps: arranging a cup-like body, formed of a plastic material, and comprising a base end, an open end, and a side wall and having a plurality of longitudinal grooves formed on an outer side of the side wall and extending from the base end to the open end, a plurality of longitudinal bulges corresponding to said longitudinal grooves on an inner side of the side wall, and a plurality of positioning seats for a positioning of the magnets, said positioning seats being defined between one longitudinal bulge and the next along the inner side of the side wall; inserting the central core into the cup-like body and inserting the permanent magnets in the positioning seats between the central core and the inner side of the side wall of the cup-like body; injecting a plastic material around the cup-like body in order to obtain a cage-like structure, said plastic material filling volumes above and below the ends of the cup-like body to form opposite bottoms of the cage-like structure, said plastic material filling the longitudinal grooves of the cup-like body to form longitudinal columns that connect said opposite bottoms.