US Patent 7587268 Control system for internal combustion engine

A control system for an internal combustion engine, which is capable of ensuring excellent fuel economy of the engine and enhancing the responsiveness of the output of the engine when acceleration is demanded. The control system calculates a lift control input for controlling a variable valve lift mechanism, based on a cam phase of a variable cam phase mechanism, and calculates a demanded acceleration indicative of the degree of acceleration demanded of the engine. Further, the control system calculates a value of phase control input for controlling the variable cam phase mechanism with priority to the engine output, and calculates a value of the same with priority to fuel economy of the engine, and selects between the values of phase control input, based on the demanded acceleration.