EMISSION CONTROL SYSTEM FOR VEHICLES POWERED BY DIESEL ENGINES

摘要

An NOx emission system for diesel powered vehicles has a "Y" exhaust system with an NOx abdsorber catalyst (20A, 20B) in each leg (15, 16) and an oxidation catalyst (19) in the combined leg (18). One bank of cylinders sends exhaust gases to one of the "Y" legs (15) while a second bank of cylinders send exhaust gases to the other "Y" leg (16). Composition of the exhaust gases in each leg is independently controlled by the engine's ECU so that exhaust gases in one leg are rich for regenerating the NOx adsorber catalyst in that leg while exhaust gas composition in the other leg is lean so that the combined gas stream is always lean and reductant slip is oxidized in the oxidation catalyst (19).