Patent ID: 7341028

Claim:
A hydraulic engine valve actuation system comprising: a first hydraulic actuator configured to actuate an engine valve between an engine valve closed position and a first lift, the first lift being defined by a fixed stop associated with the first hydraulic actuator; a second hydraulic actuator configured to the engine valve between an engine valve closed position and a second lift, the second lift being defined by a fixed stop associated with the second hydraulic actuator, the second lift being greater than the first lift; first control valving coupled to the first hydraulic actuator to controllably hydraulically couple the first hydraulic actuator to a source of hydraulic fluid under pressure or to a hydraulic drain; second control valving coupled to the second hydraulic actuator to controllably hydraulically couple the second hydraulic actuator to a source of hydraulic fluid under pressure or to the hydraulic drain; a unidirectional dashpot operative only when engine valve approaches the second lift to limit engine valve velocity as the engine valve approaches the second lift; and a unidirectional dashpot operative only when engine valve approaches the closed position to limit engine valve velocity as the engine valve approaches the engine valve closed position from the second lift.