A system and method for actuating one or more engine valves is provided.
In particular, systems and methods for providing variable valve actuation
to improve engine performance are provided. Embodiments of the present
invention may be used in conjunction with positive power, engine braking,
and/or exhaust gas recirculation operation of an internal combustion
engine. In one embodiment, the system comprises: a valve train element; a
housing disposed intermediate the valve train element and the engine
valve; an outer piston slidably disposed in a bore formed in the housing,
the outer piston having a cavity formed therein; an inner piston slidably
disposed in the outer piston cavity; and a valve in communication with
the outer piston cavity, the valve having more than one position, wherein
the position of the valve determines the timing of the engine valve
event.