Engine including system and method for reducing oil pull-over in combustion chamber

摘要

An engine assembly may include an engine structure, a piston, a first valve and a first valve actuation assembly. The engine structure may define a combustion chamber and a first port in communication with the combustion chamber. The piston may be located within the combustion chamber and be reciprocally displaceable between a top dead center position and bottom dead center position. The first valve may selectively open and close the first port. The first valve actuation assembly may be engaged with the first valve and be operable in first and second modes. The first valve actuation assembly may be operated in the first mode when fuel is provided to the combustion chamber and operated in the second mode when fuel is cutoff from the combustion chamber. The first mode and second modes may provide different opening durations of the first valve in order to reduce vacuum in the combustion chamber.