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With the introduction of common rail fuel injection system enabling multiple injections per stroke and stringent pollutant emission standards, the optimization and calibration of modern compression ignition direct injection (CIDI) engines become more complex. Thus, a simple and efficient tool for CIDI combustion simulation with arbitrary fuel injection profile is required today. A crank-angle resolved combustion model was developed and validated by using a fuel injection rig and an engine dynamometer for the parameterization. With the calibrated models, accurate prediction of the in-cylinder pressure and NOx and also a virtual dynamometer mapping are possible. The results from these virtual mappings can be used to calibrate the black-box combustion models in control-oriented, dynamic Mean Value Models (MVM).

Over the last decade, many methods have been proposed for estimating the in-cylinder combustion pressure or the torque from instantaneous crankshaft speed measurements. However, such approaches are typically computationally expensive. In this paper, an entirely different approach is presented to allow the real-time estimation of the in-cylinder pressures based on crankshaft speed measurements. The technical implementation of the method will be presented, as well as extensive results obtained for a V-6 S.I. engine while varying spark timing, engine speed, engine load and EGR. The method allows to estimate the in-cylinder pressure with an average estimation error of the order of 1 to 2% of the peak pressure. It is very general in its formulation, is statistically robust in the presence of noise, and computationally inexpensive.