Motion planning for experimental air path control of a variable-valve-timing spark ignition engine

Air path control of a spark ignition engine without an EGR loop, equipped with variable-valve-timing (VVT) actuators, is addressed in this paper. VVT devices are used to produce internal exhaust gas recirculation, providing beneficial effects in terms of fuel consumption and pollutant emissions reduction. However, VVT actuators affect the fresh air charge in the cylinders. This has an impact on the torque output (leading to driveability problems) and on the fuel/air ratio (FAR) (leading to pollution peaks). To compensate for these undesirable effects, a new approach is proposed. Supportive experimental results show the relevance of this approach.