Patent ID: 7047730
Filing Date: 2006-05-23
Classification: F01N,F02B,F02D,Y02T

Abstract:
1. A method for de-sulfurizing a NO x adsorber catalyst in an exhaust system of a diesel engine that includes a diesel oxidation catalyst in upstream flow relation to the NO x adsorber catalyst, the method comprising: a) controlling certain aspects of engine operation to cause the temperature of exhaust gases passing from the diesel oxidation catalyst to increase from a temperature range that is too low to cause de-sulfurization of the NO b) continuing controlling those aspects of engine operation to maintain the temperature of exhaust gases passing from the diesel oxidation catalyst within the de-sulfurization temperature range; wherein steps a) and b) collectively comprise controlling the relationship between engine fueling and mass airflow through an intake system of the engine to cause the engine to operate at a desired air-fuel ratio slightly richer than stoichiometric by closed-loop controlling both an intake throttle that selectively restricts airflow passing through the intake system and post-injection fueling that occurs after a main fuel injection, and step b) further comprises maintaining the temperature of exhaust gases passing from the diesel oxidation catalyst within the de-sulfurization temperature range by closed-loop controlling the quantity of engine exhaust gas being recirculated through the engine.