Patent ID: 7593805

Claim:
A control system for an internal combustion engine, comprising: a variable valve lift mechanism that changes a valve lift which is a lift of an intake valve of the engine by driving a movable part thereof, and includes a restriction part for having said movable part abut thereagainst, for thereby restricting the valve lift such that the valve lift does not exceed a predetermined limit lift; a variable intake air amount mechanism that changes an intake air amount of the engine; operating condition-detecting means for detecting an operating condition of the engine; abutment determination means for determining whether or not said movable part is in abutment with said restriction part; control means for controlling said variable intake air amount mechanism based on the detected operating condition of the engine, when said abutment determination means determines that said movable part is in abutment with said restriction part; valve lift-detecting means for detecting the valve lift; target valve lift-determining means for determining a target valve lift; and control input-calculating means for calculating a control input for controlling said variable valve lift mechanism with a predetermined control algorithm such that the detected valve lift follows up the determined target valve lift; wherein said predetermined control algorithm includes a disturbance suppression parameter for suppressing influence of disturbance applied to said variable valve lift mechanism, and wherein said control input calculating means includes disturbance suppression parameter-setting means for setting the disturbance suppression parameter such that a degree of suppression of the influence of the disturbance by the disturbance suppression parameter is made smaller when a determination that said movable part is in abutment with said restriction part is made than before the determination is made.