Limited angle torque motor with high torque output multiple coils and

Abstract

Limited angle torque motor includes a rotor assembly having one or more permanent magnets which are magnetized in the diametrical direction and a stator assembly having a plurality of axially spaced pairs of stator pole pieces, each pair having a stator coil extending circumferentially therearound. Each stator pole piece includes a generally axially extending pole blade and a radially outwardly extending flange portion at one end only of each pole piece, said flange portions being at opposite ends of the pole pieces of each pair. One or more of the stator coils and associated pairs of pole pieces may be rotationally offset with respect to one or more other coils and associated pairs of pole pieces to provide for the reshaping or widening of the resulting magnetic reluctance and interaction of magnetic fields torques versus rotation characteristics for a given motor design. Also, additional magnetic stator pole pieces may be provided at one or both ends of the stator assembly, and the rotor assembly including its permanent magnet(s) may be extended beyond one or both ends of the stator assembly into the additional magnetic stator pole pieces in order to substantially increase the magnetic reluctance torque (centering spring rate) and thus the centering tendency and natural frequency of the motor rotor and output shaft.