Remote Combustion Sensing Methodology for PCCI and Dual-Fuel Combustion Control

The increasing request for pollutant emissions reduction spawned a great deal of research in the field of innovative combustion methodologies, that allow obtaining a significant reduction both in particulate matter and NOx emissions. Unfortunately, due to their nature, these innovative combustion strategies are very sensitive to in-cylinder thermal conditions. Therefore, in order to obtain a stable combustion, a closed-loop combustion control methodology is needed. Prior research has demonstrated that a closed-loop combustion control strategy can be based on the real-time analysis of in-cylinder pressure trace, that provides important information about the combustion process, such as Start (SOC) and Center of combustion (CA50), pressure peak location and torque delivered by each cylinder. Nevertheless, cylinder pressure sensors on-board installation is still uncommon, due to problems related to unsatisfactory measurement long term reliability and cost. In order to overcome the issues related to in-cylinder pressure measurement, this paper demonstrates that the indicated quantities used in closed-loop control strategies can be accurately estimated using low-cost reliable sensors, such as accelerometers or crankshaft speed sensors. In this paper, an overall methodology for indicated quantities estimation has been applied both to PCCI and Dual-Fuel combustion. These innovative combustion methodologies have been performed using a light-duty Common-Rail Diesel engine. The algorithms proved to be suitable for real-time indicated quantities estimation in both cases.