Patent ID: 8336300

Claim:
A system for processing particulate matter of a gasoline engine, comprising: a gasoline engine having an exhaust system; a device including at least an oxidation catalyst and a particulate filter that is disposed in said exhaust system, said oxidation catalyst absent of an oxygen storage medium, said device an aftertreatment device located farthest upstream in said exhaust system; a three-way catalyst disposed in said exhaust system downstream of said device; a first oxygen sensor disposed in said exhaust system at a location downstream of said device and upstream of said three-way catalyst, said oxygen sensor being a farthest upstream located oxygen sensor in said exhaust system; and a controller adjusting fuel delivered to at least a cylinder of said gasoline engine to increase oxidation of soot held by said particulate filter while maintaining a substantially stoichiometric mixture of exhaust gases flowing through said three-way catalyst, and retarding spark and increasing air flow to said gasoline engine when a temperature of said particulate filter is less than a threshold and when an amount of soot held by said particulate filter exceeds a threshold soot amount.