Cummins Inc.
EXHAUST GAS RECIRCULATION FLOW CONTROL FOR REDUCING EMISSIONS WITH VARIABLE DISPLACEMENT INTERNAL COMBUSTION ENGINES

Abstract:

Managing firing fraction transitions of a variable displacement internal combustion engines by (a) avoiding transport delays in an Exhaust Gas Recirculation (EGR) feed by starting movement of an EGR valve position after a decision to transition to a new firing fraction has been made, but prior to the start of the transition and (b) adjusting the EGR valve as needed during the transition so as to maintain an EGR fraction within a predetermined range during the transition. By performing both (a) and (b), spikes of nitrous oxide (NO.sub.x) and/or hydrocarbon emissions are reduced or altogether eliminated during the transition.