A method of operating a diesel engine system having LNT and SCR aftertreatment devices

摘要

A method of operating a diesel engine 10 having LNT 11 and SCR 13 aftertreatment devices arranged in series to receive exhaust gas from the engine is disclosed in which the engine is operated in a rich early injection mode to generate ammonia in the LNT for storage in the SCR located downstream from the LNT. This reduces the amount of soot produced permitting longer operation of the engine in rich early injection mode and further may reduce the use of PGM material in the LNT and increase the amount of ammonia for use in the SCR.