Patent ID: 8551384

Claim:
A method for producing a rotor for an external rotor electric motor, wherein the method comprises the steps of: providing a cup-shaped rotor support structure having a bottom and a side wall; placing a plurality of magnetic poles in said cup-shaped rotor support structure, said magnetic poles arranged and distributed on said side wall in a circumferential pattern along said side wall, said magnetic poles being separated, along said circumferential pattern, by sections of predetermined width; inserting a cylindrical mold portion into the cup-shaped rotor support structure to define a mold volume of uniform thickness between the cylindrical mold portion and said side wall; inserting an elastomeric material in a liquid state into said mold volume to fill the sections of predetermined width between said magnetic poles; hardening said elastomeric material to form a substantially annular massive structure of uniform thickness with the magnetic poles, said annular massive structure being integral with said cup-shaped rotor support structure; and after hardening of said elastomeric material, removing said cylindrical core mold portion from said cup-shaped rotor support structure, such that said cup-shaped rotor support structure, said magnetic poles and said annular massive structure form the external permanent-magnet rotor.