Continuously Variable Cam Phaser Optimization for Spark Ignition Gasoline Engine: A Computational Methodology Approach

The future carbon dioxide regulations, which will go beyond the EURO IV, imply the development of more and more complex combustion systems. For this reason the activity was performed on a small gasoline engine equipped with a continuously variable cam phaser and a high turbulence combustion chamber. In order to reduce time and cost required by calibration and development activity due to this complex system an experimental/computational approach was applied. Overcoming one of the well-know limits of the 1-dimensional tools an empirical equation to predict the cyclic combustion stability was found. The prediction relationship is able to provide a preliminary cam phaser optimised position map based on the maximum combustion stability requirements. Besides it represents an internal/external EGR ‘tolerability’ related to the engine used. A quite satisfactory agreement between predicted and measured data was found.