Investigation on the validity region of online combustion and torque models of gasoline engines with retarded ignition

The recently proposed online mean-value thermodynamic combustion model suffers from its error-prone CA50 prediction. In an effort to improve the accuracy of CA50 prediction in the case of ignition retard, this chapter demonstrates the convergence of normalized IMEPH-CA50 predictions towards a unanimous characteristic curve indiscriminately for various gasoline engine selections, speeds and loads. For the first time, this chapter reveals the physical principle of a characteristic curve via an ideal-heat-release model and thereby formulates a validity region of the IMEPH-CA50 predictions. The predicted values outside of the region will then be corrected by a surrogate of the characteristic curve. In this way, ECUs successfully identify invalid CA50 predictions online and modulate them towards the actual values. Large-scale experiments have shown the developed method improves the accuracy in CA50 prediction, while preserving the high accuracy of IMEPH prediction. © 2013 Springer-Verlag Berlin Heidelberg.