Camless engines with compression release braking

摘要

A camless internal combustion engine has electronically or computer controlled, electrically operated hydraulic actuators (40,50) for selectively opening the engine cylinder valves (20,30). The engine is capable of operating in either positive power mode or compression release engine braking mode. The pressure of the hydraulic fluid available for application to the hydraulic actuators (40,50) is automatically adjusted from a relatively low pressure during positive power mode to a relatively high pressure during compression release engine braking mode. The stroke lengths of the engine cylinder valves (20,30) may be automatically adjusted for various engine operating conditions using feedback loops that include sensors (64) for detecting the amount of opening of each engine cylinder valve (20,30) whose stroke length is to be controlled in this manner. The shapes of the valve opening and closing trajectories as a function of engine crank angle may similarly be varied in many other respects.