Patent ID: 9739190
Date: 2017-08-22
CPC Classifications: F01N,F02B,Y02T

Claim:
1. A method for controlling reductant injection into an exhaust gas feedstream of a lean-burning internal combustion engine, wherein the reductant is injected into the exhaust gas feedstream upstream of a selective catalytic reduction (SCR) device, the method comprising: determining an upstream NOx gas concentration in the exhaust gas feedstream upstream of the SCR device; determining a measured downstream NOx gas concentration in the exhaust gas feedstream based upon a signal output from a sensor configured to monitor NOx gas concentration downstream of the SCR device; determining an estimated downstream NOx gas concentration in the exhaust gas feedstream based upon an executable model operative to determine NOx gas concentration downstream of the SCR device; determining a first correlation between the upstream NOx gas concentration and the measured downstream NOx gas concentration; determining a second correlation between the upstream NOx gas concentration and the estimated downstream NOx gas concentration; executing a feed-forward proportional-integral control routine to generate an ammonia storage correction term based upon the first and second correlations; and controlling the reductant injection based upon the ammonia storage correction term.