Locating the Main Conversion Period Exactly, Using a Newly Developed Characteristic Value of the Combustion Pressure in an SI Engine

This paper describes a new way to locate the position of the combustion process in a spark-ignited engine. This method uses a characteristic value which is calculated from indicated high pressure (Pmax). This calculation requires much less time than traditional methods and allows the on-board-management (OBM) system to predict misfire cycles, and therefore, to avoid them.

The new characteristic value correlates closely to given percentages of the rate of converted energy, and has been tested using high relative air/fuel ratios (λ), high rates of exhaust gas recirculation (EGR), and different fuels. Use of this method in the OBM system allows extremely sensitive adjustments of ignition timing (α_IG), which maximize efficiency and minimize pollutant emissions.