A Methodology for the Definition of Optimal Control Strategies of a VVT-Equipped SI Engine

A theoretical-experimental analysis of a VVT engine and a methodology for the definition of its control map is presented. The analyses are based on the employment of a very accurate engine code, developed by the authors, which belongs to the category of the wave propagation models. The code is validated by comparison with experimental data collected on a traditionally fixed- and a variable-valve timing engine as well. The model is also linked to an efficient optimization procedure, which is able to select - for each assigned operating condition - the most appropriate values of control parameters (spark advance, intake/exhaust valve opening/closing, and valve lift), with the objective of pursuing torque or BSFC improvements, idle stability and emission control.