Patent ID: 6698191
Filing Date: 2004-03-02
Classification: B01D,F01N,F02D,Y02T

Abstract:
A system for controlling reductant addition into lean exhaust gases discharged from an internal combustion engine, the reductant being added upstream of a catalyst coupled to the engine, comprising:an injector for adding the reductant into the exhaust gases; and an engine controller operably connected to the engine and said injector which actuates said injector to supply the reductant in response to an indication that temperature of the catalyst is greater than a predetermined temperature, provides an estimate of a quantity of reductant stored in the catalyst, and when said quantity exceeds a predetermined quantity, substantially discontinues said addition of reductant wherein the catalyst comprises active sites and inactive sites on which reductant is stored and said estimate of a quantity stored in the catalyst is based on an estimate of reductant stored on active sites.