Patent ID: 7685980

Claim:
A valve actuation system for controllably varying angular duration of an opening event of a combustion valve in an internal combustion engine with respect to rotation of an engine crankshaft, comprising: a) a rocker assembly pivotably disposed on a pivot shaft for opening and closing said valve, said pivot shaft having an axis of rotation in a fixed position relative to said engine; b) a first cam lobe disposed on an opening camshaft driven by said crankshaft of said engine and engaging said rocker assembly for controlling at least said opening event of said valve, said first cam lobe including a first nose portion configured to produce zero acceleration of said valve at maximum valve lift; and c) a second cam lobe disposed on a closing camshaft operationally connected to said opening camshaft via a cam phaser and selectively engaging said rocker assembly for variably controlling a closing event of said valve, said second cam lobe including a second nose portion configured to produce zero acceleration of said valve at maximum valve lift, wherein a shift in phase between said first cam lobe and said second cam lobe effected by said cam phaser on said closing camshaft changes a closing point of said valve, and wherein a transition point at which said second cam lobe takes control of said rocker assembly from said first cam lobe occurs when said first nose portion and said second nose portion are in contact with said rocker assembly.