A Novel Approach to Real-Time Estimation of the Individual Cylinder Combustion Pressure for S.I. Engine Control 1999-01-0209

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. The chief advantage of this approach is that all the complexities of the actual physical system (combustion phenomena, engine dynamics) are self-extracted from the data in a “mapping” phase. Once this information has been pre-computed, the pressure estimation can be achieved in real-time with very few computational operations. This method has high potential for pressure-based engine control strategies, while eliminating the need for in-cylinder pressure sensors. An overview of its potential implementation in an engine control scheme will also be presented.