Exhaust purifying apparatus and exhaust purifying method for internal combustion engine

摘要

An exhaust purifying apparatus estimates an accumulation amount of particulate matter trapped about a catalyst in an exhaust system. When the estimated accumulation amount is equal to or more than a permissible value, the apparatus executes PM elimination control for supplying unburned fuel component to the catalyst. The apparatus sets the estimated accumulation amount to zero at the completion of the PM elimination control. When execution of the PM elimination control becomes possible after suspension of the control, the apparatus resumes the PM elimination control even if the accumulation amount is less than the permissible value. Therefore, The estimated accumulation amount is prevented from being significantly deviated from the actual accumulation amount due to suspension.