Electropneumatic rotary actuator having proportional fluid valving

Abstract

An electropneumatic rotary actuator has proportional fluid valving providing introduction and exhaust of pressurized fluid to and from a working chamber of the actuator. By control of the admission angle and venting angle of the fluid pressure and flow with respect to top dead center and bottom dead center of a working piston of the actuator both the torque level and gas consumption rates of the actuator may be controlled. Further by modulating the average working fluid pressure within the actuator the stiffness or resistance to backdriving of the actuator may be controlled. A proportional linear electrical solenoid is disclosed and employed in the actuator of the present invention to drive a double-acting closed-centered valve device. Because of its lightweight, relatively simplicity, high stiffness to backdriving, and relatively low gas consumption rate, the present actuator is expected to find application in airborne vehicles.