Patent ID: RE40503

Claim:
A hybrid rotary actuator comprising: a housing; a stator having first and second pole pieces disposed in said housing; a rotor disposed in said housing between said first and second pole pieces of said stator, said rotor being rotatable relative to said stator between an unactuated position and an actuated position; said first pole piece of said stator having a first stator surface which faces toward and is spaced from a first rotor surface on said rotor by a first working air gap, said first stator surface on said first pole piece of said stator and said first rotor surface on said rotor being spaced apart by the same distance when said rotor is in the unactuated position as when said rotor is in the actuated position so that the extent of the first working air gap along the axis of rotation of the rotor remains constant during rotation of said rotor between the unactuated and actuated positions; said second pole piece of said stator having a second stator surface which faces toward and is spaced from a second rotor surface on said rotor by a second working air gap, said second stator surface on said second pole piece of said stator and said second rotor surface on said rotor being spaced apart by a smaller distance when said rotor is in the actuated position than when said rotor is in the unactuated position so that the extent of the second working air gap along the axis of rotation of the rotor decreases during rotation of said rotor between the unactuated and the actuated positions; and a coil which is disposed in said housing and extends around at least a portion of said actuator, said coil being energizable to provide magnetic flux which passes across the space between said first stator surface and said first rotor surface and which passes across the space between said second stator surface and said second rotor surface during at least a portion of the rotation of said rotor between the unactuated position and the actuated position, said flux biasing said rotor to move from said unactuated position towards said actuated position , wherein said first stator surface and said first rotor surface have flat configurations, said second stator surface and said second rotor surface have flat configurations and are inclined with respect to said first stator surface and said first rotor surface .