Exhaust emission control apparatus for internal combustion engine and exhaust emission control method

摘要

In an exhaust emission control apparatus for an internal combustion engine (10), a state where a large amount of smoke is generated is predicted on the basis of an operation state of the internal combustion engine, that is, the internal combustion engine is in an acceleration state, and a combustion mode of the internal combustion engine is changed. Upon prediction of the aforementioned state, the fuel as the additive is forcedly added to the exhaust gas through an addition valve (46) having an injection hole (60) communicated with an exhaust passage (14). This makes it possible to maintain the addition valve (46) filled with the fuel upon generation of a large amount of smoke, thus preventing the smoke from intruding into the addition valve (46). Accordingly, clogging in the addition valve (46) owing to deposited smoke may be prevented.