HYDRAULIC VALVE ACTUATOR FOR ACTUATING A GAS EXCHANGE VALVE

An hydraulic valve actuator for actuating a gas-exchange valve in a combustion cylinder of an internal combustion engine has an operating piston delimiting two pressure chambers, of which the lower pressure chamber acting in the valve-closing direction is permanently charged with fluid pressure via which an intake and return line can be charged by, or relieved of, fluid pressure. To brake the gas-exchange valve in the final phase of the closing procedure to reduce the set-down speed, the return line of the upper pressure chamber is split between two discharge openings, which are connected to one another and arranged in the housing with axial clearance, the upper discharge opening being coupled to a restrictor and the lower discharge opening being displaceable relative to the operating piston and disposed in its displacement path such that it may be closed thereby at a defined distance, prior to reaching its upper limit position.