Exhaust Pressure Estimation Using a Diesel Particulate Filter Mass Flow Model in a Light-Duty Diesel Engine Operated With Dual-Loop Exhaust Gas Recirculation and Variable Geometry Turbocharger Systems

This paper presents a novel method to estimate an exhaust pressure at 357 different steady-state engine operating conditions using a diesel particulate filter (DPF) mass flow model to precisely control the air quantity for a light-duty diesel engine operated with dual-loop exhaust gas recirculation (EGR) and variable geometry turbocharger (VGT) systems. This model was implemented on a 32 bit real-time embedded system and evaluated through a processor-in-the-loop-simulation (PILS) at two transient engine operating conditions. And the proposed model was validated in a vehicle. By applying Darcy's law, the DPF mass flow model was developed and shows a root mean square error (RMSE) of 3.7 g/s in the wide range of the DPF mass flow and above 99% linear correlation with actual values. With such reasonable uncertainties of the DPF mass flow model, the exhaust pressure was estimated via the application of a nonlinear coordinate transformation to the VGT model. The DPF mass flow based exhaust pressure estimation exhibits below 6% error of the exhaust pressure under steady-state conditions. The method was also validated through the PILS and the vehicle test under transient conditions. The results show a reasonable accuracy within 10% error of the exhaust pressure.