ROTARY ACTUATORS WITH MULTIPOLE RING MAGNETS

Rotary actuators are electromagnetic devices developing mechanical tor que with limited rotary motion. Because of their simplicity and low co st they are finding more and more applications, especially in the auto motive field. This paper describes a novel homopolar rotary actuator w ith a ring-type radially magnetized multipolar permanent magnet featur ing a high force density ''transverse flux'' configuration which perfo rms a spring action by developing electromagnetic torques with limited angular movement. Because of the magnetically complicated and nonsymm etrical rotary actuator configuration, the analysis of this actuators is based on 3-D finite element software. The analysis, which is well s upported by test results, shows that symmetrical magnetic forces in bo th directions of rotation were achieved with a stable equilibrium posi tion, satisfying all design requirements to enhance the basic hydrauli c power steering system of passenger vehicles.