Patent ID: 6813883
Filing Date: 2004-11-09
Classification: F01N,F02D,F02M,Y02T

Abstract:
A method for controlling an air-fuel mixture in an internal combustion engine, comprising:determining a temperature of a downstream emission control device, said downstream emission control device located following an upstream emission control device; oxidizing hydrocarbons stored in said downstream emission control device when said temperature of said downstream emission control device is greater than a predetermined temperature by providing an air amount in a location following said upstream emission control device and before said downstream emissions device, where said air amount is provided by an air pump, and wherein said oxidizing hydrocarbons is accomplished by adjusting said air pump to provide a varying amount of air mass to said downstream device to oxidize hydrocarbons without lowering said temperature of said downstream device below a predetermined threshold; and adjusting the air/fuel ratio in the engine rich of stoichiometry during oxidation of said hydrocarbons.