Patent Document ID: 9752548
Application ID: 14272980
Patent Flag: 1

Claim One:
1. A method of real-time evaluation of at least pressure in a combustion chamber of an electronically controlled spark plug ignition engine by sensing an ionization current flowing through a spark plug, the method comprising: refining a mathematical model of the electronically controlled spark plug ignition engine and the combustion chamber through a calibration campaign of tests conducted on a test engine equipped with specific sensors of combustion chamber pressure, and a first engine parameter by iteratively testing interactive performance of correlation coefficients of related terms of a mathematical expression of the mathematical model and comparing an estimated pressure value generated by the mathematical model with a pressure value as measured by a sensor; storing in a matrix or look-up table a set of time invariant correlation coefficients of the terms when a residual mismatch between the estimated pressure value generated by the mathematical model compared with the measured value remains within a maximum spread; and sensing the ionization current in the electronically controlled spark plug ignition engine when the electronically controlled spark plug ignition engine is running, measuring or calculating at least one or more significant features of a waveform of the sensed ionization current and processing the at least one or more significant features of the waveform together with the matrix or look-up table and with a set of actual values of parameters of the electronically controlled spark plug ignition engine when the electronically controlled spark plug ignition engine is running for producing an evaluated value of the combustion chamber pressure.