Patent ID: 7482717

Claim:
An electrically-powered linear actuator assembly, the linear actuator assembly comprising: a housing, the housing having a first housing end, a second housing end, and a longitudinal housing axis, the housing axis extending intermediate the first and second housing ends; a thrust assembly, the thrust assembly comprising a screw shaft, a nut, and a nut axis of rotation, the nut being threadably received upon the screw shaft and rotatable about the nut axis of rotation for axially displacing the screw shaft relative to the nut, the screw shaft being axially displaceable intermediate a retracted, relaxed position and an actuated, loaded position; a commutatable motor assembly, the motor assembly comprising a rotor assembly, a stator assembly, and a longitudinal motor axis, the motor axis being collinear with the nut axis of rotation, the rotor assembly being coupled to the nut for imparting rotational motion thereto, the stator assembly being axially fixed relative to the housing axis, the rotor assembly being axially displaceable relative to the stator assembly along the motor axis for automatically varying the back electromotive force therebetween, the variable back electromotive force for enabling high speed-low force shaft displacement adjacent the relaxed position and for enabling low speed-high force shaft displacement adjacent the loaded position; and rotor-position-encoding means, the rotor-position-encoding means for sensing rotor assembly position and governing motor assembly commutation.