Electro-hydraulic controlled valve actuator system

A hydraulic valve actuator comprising a generally cylindrical housing defining a piston cylinder, piston means mounted for reciprocation within said piston cylinder, compressible resilient means yieldable biasing said piston means in one direction, means in said cylinder for receiving a valve shaft rotatively mounted on a first side of said piston means, yoke means connecting said piston means for rotating said valve shaft in response to said reciprocation of said piston means, said reciprocating piston means defining a variable volume hydraulic fluid reservoir in said cylinder, said cylinder further having a pair of ports for connection with conduit means for selectively delivering hydraulic fluid between opposite sides of said piston means for effecting, together with said resilient means, said reciprocation of said piston means.

An electro-hydraulic controlled valve actuator comprising:

• an actuator member including a cylinder, piston means mounted for reciprocation within said cylinder, and means responsive to said piston means for selectively rotating a valve shaft, a hydraulic pump joined with said cylinder for selectively pumping hydraulic fluid for reciprocating said piston means in said cylinder in a first direction to rotate said valve shaft in a first corresponding direction, and a valve for selectively joining conduit means connected with said cylinder at opposite sides of said piston means, compressible resilient means yieldably biasing said piston means in a second direction opposite said first direction to rotate said valve shaft in a second corresponding direction in the absence of sufficient opposing hydraulic pressure supplied by said pump, and control means for selectively energizing said valve or said hydraulic pump for rotating said valve shaft as required to achieve and maintain a desired flow rate through the valve.