Patent ID: 6765320
Filing Date: 2004-07-20
Classification: H02K

Abstract:
A claw pole type of actuator of a single phase structure, comprising:a stator yoke comprising a pair of substantially circular plane yokes formed of a soft magnetic material; a plurality of pole teeth which protrude from an inner peripheral edge of the respective plane yokes and which are disposed to face each other, extending in an axial direction; and a cylindrical ring provided on an outer peripheral edge of one of said plane yokes extending in a same direction as said pole teeth; an armature comprising an armature coil further comprising a magnet wire winding in a coil receiving section shaped like an annular recess formed by said plane yokes, said pole teeth, and said cylindrical ring of said stator yoke; a stator assembly which has flanges with bearings provided on both end surfaces of said armature and in which a rotor provided with a rotor magnet comprising a permanent magnet facing said pole teeth of said stator yoke with a minute gap provided therebetween, wherein the rotor magnet has a cylindrical shape, and magnetic pole peak positions of at least one of N and S poles thereof are shifted in a circumferential direction as a function of axial position thereof within a range of 20 to 60 degrees in terms of electrical angle; and, a stop mechanism comprising a first stop positioned at a first angle between 0 degrees and 90 degrees in terms of electrical angle and a second stop positioned at a second angle between 90 degrees and 180 degrees in terms of electrical angle, wherein said first and second angles are arranged such that a rotating position of said rotor magnet driven by excitation of the armature coil between 0 and 90 degrees or between 90 and 180 degrees in terms of electrical angle is maintained by a detent torque at said first angle or said second angle respectively thereof upon switching to non-excitation of the armature coil.