Method of optimizing reductant addition to an SCR catalyst coupled to an internation combustion engine

摘要

A method for controlling reductant injection into a catalyst (14) coupled to an internal combustion engine (10), comprises determining NO_X conversion and ammonia concentration and if the post-catalyst ammonia concentration is less than an allowable fraction and level, the amount of reductant is increased as long as there is an increase in NO_X conversion and the post-catalyst ammonia concentration is kept below the allowable fraction and level. Otherwise, the amount of reductant injected is decreased until the post-catalyst ammonia concentration is below the allowable fraction and level.