Patent ID: 6384504
Filing Date: 2002-05-07
Classification: H02K

Abstract:
An electric machine comprising a stator and an external circumferential rotor separated by a cylindrical air gap, said rotor having an axis, a head portion adjacent the air gap and a foot portion and being formed with a plurality of permanent magnet assemblies magnetized substantially in the circumferential direction, and a plurality of magnetic flux conducting piece assemblies, each magnetic flux conducting piece assembly being arranged between two permanent magnets;wherein each permanent magnet assembly has an increasing circumferential width from the head portion to the foot portion, and each said magnetic flux conducting piece assembly has a decreasing circumferential width from the head portion to the foot portion; wherein each conducting piece assembly is composed of a plurality of stacked metal sheets, the stacked sheet metal assembly being retained on the rotor by means of a bolt axially extending through the stacked sheet metal assembly; wherein each permanent magnet assembly is composed of a plurality of plate-like permanent magnets stacked in the direction of the rotor axis; and wherein said external rotor has a cup-shaped configuration and comprises a mounting portion, on only one side, axially beside the permanent magnet assemblies and the conducting piece assemblies, the permanent magnet assemblies and the bolt being mounted to the mounting portion of the rotor.