EXHAUST EMISSION CONTROL DEVICE OF INTERNAL COMBUSTION ENGINE

摘要

PROBLEM TO BE SOLVED: To prevent generation of bore flashing due to additional fuel injection. SOLUTION: A cylinder fuel injection valve 111 of each of cylinders is controlled by an electronic control unit(ECU) 30 of a diesel engine 1. An exhaust air-fuel ratio is made less than a stocchiometric air-fuel ratio by carrying out additional fuel injection to an expansion stroke or to an exhaust stroke in addition to main fuel injection from the cylinder fuel injection valve when releasing NOx absorbed from a NOx occluding reducing catalyst 70 arranged in an exhaust passage 3 by the ECU. Additional fuel injection is carried out once for every one cylinder stroke cycle in each of cylinders, the number of cycles to carry out additional fuel injection continuously with the one cylinder is limited to the number not to cause bore flashing, and a term of period to stop additional fuel injection for a period of time to sufficiently recover lubricating oil film thickness of a wall surface in the cylinder until following additional fuel injection is started after the additional fuel injection is continuously carried out is provided.