Low-profile brushless DC motor esp. for fan - has magnetic field confined within housing by selection of ratio of pole width to axial length

摘要

The motor has the winding (5) of the stator permeated by the field of the axially magnetised rotor (10) on which the pole distribution (t) is related to the axial length (a) in such a way that the axial field between adjacent poles (10a, 10b) of opposite polarity in the circumferential direction (U) intersects the range of stator windings (5) within the housing of the motor, and does not extend to its cover (2). ADVANTAGE - With no closed loop of iron on the stator winding side turned away from the permanent-magnet rotor, min. stray field escapes from the motor housing.