An exhaust emission control system having improved ability to regenerate an exhaust emission control device

摘要

PPROBLEM TO BE SOLVED: To provide an exhaust emission control device for an internal combustion engine capable of learning a deposit ratio and an evaporation rate, and more appropriately adding fuel according to the geometric machine difference of a vehicle and fuel property. PSOLUTION: The exhaust emission control device for the internal combustion engine includes: a NOx storage reduction catalyst 34 provided in an exhaust flow passage 26 from the internal combustion engine 1 to purify exhaust gas and also regenerating an emission control function; and a fuel adding valve 21 adding fuel to the exhaust flow passage 26 upstream of the NOx storage reduction catalyst 34. An air-fuel ratio sensor 58 is provided for detecting an air-fuel ratio in the exhaust flow passage 26 downstream of the NOx storage reduction catalyst 34. The evaporation rate is calculated based on a reaching fuel estimated mode using two pairs of displacement, air-fuel ratio and cylinder injection quantity detected at time intervals after the fuel is added, and also the deposit ratio is calculated based on the minimum peak value of the air-fuel ratio by the air-fuel ratio sensor 58 after the fuel is added, displacement at that time, and a cylinder injection quantity (S170-S210). The amount of fuel added from the fuel adding valve 21 to the exhaust flow passage 26 is calculated based on the calculated deposit ratio and evaporation rate. PCOPYRIGHT: (C)2010,JPO&INPIT