Electro-hydraulic control actuator for turbine valves

Claim 1

Electro-hydraulic control actuator assembly for turbine valves, comprising a turbine valve having a valve cone being movable between an open and a closed position of said valve, a shaft connected to said valve cone, a valve housing, an integrated compact actuator unit disposed on said valve housing and combined with said valve, said actuator unit including an electro-hydraulic converter, a hydraulic control cylinder being connected to said electro-hydraulic converter and having a control piston connected to said shaft for moving said valve cone to said open position of said valve, a power spring connected to said shaft for absorbing movement of said valve cone into said open position of said valve and for resetting said valve cone for rapid closing be spring loading, and a hydraulic fluid supply system, said supply system including a hydraulic fluid reservoir, first and second fluid pumps each being fed from said fluid reservoir and each having a pressure side, first and second electric motors each driving a respective one of said pumps, a hydraulic pressure accumulator subdivided into at least two part-accumulators, and piping disposed in said actuator unit connecting said part-accumulators to said pressure side of said pumps and to said hydraulic control cylinder for providing hydraulic fluid for an opening motion of said valve, each of said part-accumulators having a hydraulic fluid storage volume sufficient for providing hydraulic fluid for at least one full opening motion of said valve even if one of said part-accumulators is inoperative, said fluid pump having a flow capacity being dimensioned for continuously replenishing leakage losses and for slowly filling said pressure accumulator, and said second fluid pump being operable when said first fluid pump is inoperative.