Abstract: A lost motion engine valve actuation system and method of actuating an engine valve are disclosed. The system may comprise a valve train element, a pivoting lever, a control piston, and a hydraulic circuit. The pivoting lever may include a first end for contacting the control piston, a second end for transmitting motion to a valve stem and a means for contacting a valve train element. The amount of lost motion provided by the system may be selected by varying the position of the control piston relative to the pivoting lever. Variation of the control piston position may be carried out by placing the control piston in hydraulic communication with a control trigger valve and one or more accumulators. Actuation of the trigger valve releases hydraulic fluid allowing for adjustment of the control piston position. Means for limiting valve seating velocity, filling the hydraulic circuit upon engine start up, and mechanically locking the control piston/lever for a fixed level of valve actuation are also disclosed.

Abstract: Systems and methods for actuating engine valves are disclosed. The systems may include primary and auxiliary rocker arms disposed adjacent to each other on a rocker arm shaft. A rocker arm coupling assembly may be disposed between the auxiliary rocker arm and the primary rocker arm. The coupling assembly may include a piston having a curved surface disposed in a bore formed in the primary rocker arm, and a slot having a second radius of curvature formed in the auxiliary rocker arm. The piston may be selectively hydraulically locked into an extended position between the primary and auxiliary rocker arms so as to selectively transfer one or more auxiliary valve actuation motions from the auxiliary rocker arm to the primary rocker arm.