Compression ignition engine system with diesel particulate filter coated with nox reduction catalyst and stable method of operation

摘要

An engine system (10) includes an electronically controlled compression ignition engine (11) configured to bum diesel fuel to produce an exhaust with a temperature and NOx to soot ratio. An aftertreatment system (12) is fluidly connected to the engine (11) and includes a diesel oxidation catalyst (13), a reductant supply (14), and a diesel particulate filter (13) coated with a NOx reduction catalyst (23) but not the diesel oxidation catalyst (13). A soot load density in the diesel particulate filter (15) is stabilized by oxidizing soot at about a same rate as the compression ignition engine (11) is supplying soot to the aftertreatment system (12) without active regeneration. A NOx reduction reaction is catalyzed by the NOx reduction catalyst (23) on the diesel particulate filter (15).