AN ELECTRICAL SERVO-ASSISTANCE UNIT

摘要

An electrical servo assistance unit for use in a power assisted steering system comprises a stator (10) comprising a plurality of coil windings arranged at spaced locations, a rotor (8) comprising a plurality of magnets at spaced locations around its axis, an input shaft (4) and an output shaft (6) connected by a deflection member (2) which permits relative rotation of the input and output shaft in response to application of a torsional load applied therebetween the rotor being fixed to the output shaft and sharing a common axis of rotation; a commutator (12) comprising at least two conductive portions, each of which provides an electrical connection to a different coil; and at least one brush (14a, 14b) which is adapted to contact the commutator and to selectively connect at least one contact portion and its coil to an electrical supply according to the relative angular position of the brush and commutator.