Valve operators

Abstract

A spring return valve operator for actuating a valve is comprised of a spring return actuator which is loadmatched to a valve load and extracts a large fraction of its spring energy storage capacity, and a controlled actuator which is load matched to the valve load and the spring return actuator retensioning load. Within the spring return actuator, the output of nested torsion springs is transformed into various torque outputs, particularly constant torque outputs and increasing torque outputs. Spring output is transformed by eccentric spool and flexible element mechanisms or by four bar mechanisms through changes in leverage produced by varying torque arms. The output of a controlled actuator can be transformed into torque outputs which are decreasing, increasing, etc., using eccentric spool and flexible element mechanisms or using four bar mechanisms in order to produce a loadmatch to the valve load. A pneumatic controlled actuator, comprised of a piston, push rod, concentric spool and flexible elements which oppositely wrap on the concentric spool and connect to the piston and the push rod, produces a constant torque output and no side thrusting of the piston, is not subject to fouling of the flexible element, and can be used as either a single or double acting actuator. A high fatigue life spooling cable connection, which is comprised of a self adjusting multiple leg cable, is used in the spring return actuator and the pneumatic controlled actuator.