The Influence of Variable Valve Actuation on the Part Load Fuel Economy of a Modern Light-Duty Diesel Engine

An investigation has been carried out to identify how variable valve actuation (VVA) can be used to improve the part load fuel economy of a modern light-duty diesel engine. The base engine examined employed a variable geometry turbo-charger (VGT) with air to air inter-cooling, cooled exhaust gas re-circulation (EGR) and common rail fuel injection. The VVA system investigated was of the variable duration type, controlling primarily exhaust valve opening and intake valve closing events.

This paper describes how the fuel economy of the base engine was affected by the interactions of the VGT and EGR systems. It then presents simulation data that shows the methods by which fuel economy can be improved by the use of VVA, explains the phenomena that lead to this improvement and quantifies the extent to which it can be improved: Indicated and brake specific fuel consumption improvements of up to 6% and 19% respectively, were found during the course of this work.