Patent ID: 7055311

Claim:
A system for treating exhaust gases emitted from a vehicle comprising: a) a multi-cylinder diesel engine having a first exhaust manifold in fluid communication with a first plurality of cylinders and a second exhaust manifold in fluid communication with a different second plurality of cylinders; b) a first NOx adsorber catalyst in a first exhaust leg in fluid communication with said first manifold; c) a second NOx adsorber catalyst in a second exhaust leg in fluid communication with said second manifold; d) a common exhaust leg having an inlet in fluid communication with said first and second exhaust legs downstream of said first and second NOx catalysts, said common exhaust leg having an oxidation catalyst therein through which exhaust gases from said first and second legs pass after being combined in said common exhaust leg; and, e) ECU means controlling the composition of exhaust gases in said first exhaust manifold independently of the composition of exhaust gases in said second exhaust manifold in accordance with a programmed routine, to periodically produce rich gases in one exhaust manifold and lean gases in the other exhaust gas manifold and controlling the quantities of combustible gases present in said rich gas and the quantities of oxygen present in said lean gas to produce a combined gas stream in said common exhaust leg upstream of said oxidation catalyst to have a lambda of at least 1.0, and further including NOx sensors upstream and downstream of each NOx adsorber catalyst and lambda sensors upstream and downstream of each NOx adsorber catalyst, said ECU means sensing said NOx sensors to determine the start of said routine and sensing said lambda sensors to determine the end of said routine wherein said ECU means periodically switches the generation of said rich and lean gases from one exhaust manifold to the other.