Patent ID: 8251033

Claim:
A system, comprising: a tappet assembly coupled to an intake valve of an engine, said tappet assembly including a first tappet body and a second tappet body within a guide housing, wherein an oscillation of the intake valve between an opening phase and a closing phase of the intake valve is based on a relative oscillation of said first tappet body and said second tappet body within the guide housing; a cam coupled to a shaft of the engine, said cam being engaged with said tappet assembly to initiate the relative oscillation of said first tappet body to said second tappet body; a hydraulic piston positioned within the guide housing and coupled to said first tappet body for selectively varying a duration of the relative oscillation of the first tappet body to the second tappet body based upon a parameter of a hydraulic fluid supplied to the hydraulic piston, to thereby selectively vary the duration of the closing phase of the intake valve; a hydraulic fluid pressure regulator to supply pressurized hydraulic fluid to the hydraulic piston at a selective pressure; and a controller coupled to the hydraulic fluid pressure regulator, wherein said controller is configured to selectively adjust the pressure of the hydraulic fluid supplied from the hydraulic fluid pressure regulator to the hydraulic piston, based on at least one of a speed and/or load of the engine.