Application of Different Cylinder Pressure Based Knock Detection Methods in Spark Ignition Engines

The primary objective of this paper is to compare different methods of knock detection based on cylinder pressure data, with special regard to identifying knocking cycles and detecting the onset of knock. These investigations have resulted in the development of a new knock detection method based on high-pass filtered heat release. Different signal characteristics have been considered. The model has been developed on the basis of experimental data for a four-valve production engine, and verified over a wide range of operating conditions. For the purpose of thermodynamic investigations, the new knock detection algorithm allows the determination of the engine operating points that correspond to the knock limit, and their mean crank angle of knock onset.

The thermodynamic properties of the end gas at knock onset have been discussed using a zero-dimensional two-zone model. Existing empirical autoignition delay correlations implemented in the heat release model and derived by matching an Arrhenius function to recorded data on autoignition times, have been applied and compared to a modified autoignition model based on the “Franzke Knock Criterion” [1]. The prediction of knocking operation has been compared with measured data.