Abstract
Minimizing fuel consumption of passenger car vehicles can be achieved thanks to hybridization of the powertrain associated with innovative engine technologies. To feed the new high compression ratio combustion systems, air system cutting-edge technologies are used to manage air and EGR (Exhaust Gas Recirculation) quantities. Increasing EGR allows us to improve engine consumption in the high efficiency area, but it comes at the cost of a loss of stability. It is then of primary importance to be able to manage the engine near the stability limit to minimize fuel consumption. So far, the stability limit is managed in open-loop thanks to conservative calibration of the EGR quantity, implying efficiency losses. This paper addresses the combustion stability feedback control using in-cylinder pressure sensors. From this information, an indicator of stability is proposed, offering a more robust behavior in transient situations than state-of-the-art indicators. This indicator is then used to feed a controller that adapts the open-loop EGR target to go towards the stability limit. Experimental results obtained on a high efficiency gasoline engine stress the relevance of the approach in minimizing fuel consumption under real driving conditions.