Low-noise miniature electric motor

摘要

A low noise brushless dc motor has a rotor with a permanent magnet and a stator with a bearing system mounting a shaft for rotating the rotor. The bearing system includes at least one axially extending bearing surface that terminates in axially spaced apart ends defining the outer axial limits of the bearing surface. Magnetic components of the rotor and the stator define a magnetic circuit. the magnetic components have an eccentricity creating an asymmetry in the magnetic circuit that causes a resultant lateral magnetic force to be applied on the shaft at a point axially inside the outer axial limits of the bearing surface, whereby the shaft exerts a pressure along the bearing surface between both ends of the bearing surface in a direction perpendicular to the rotor axis.