A Method of Torque Estimation Utilizing Ionization Sensing Technology in Internal Combustion SI Engines

This paper describes a method of torque estimation by using in-cylinder ionization sensing technique in a internal combustion SI engine. Through the characterization of the ion current signal measured across the spark plug electrode with four parameters, two peaks of ionization signal were investigated and used to build the relationship between the net torque of engine and the ion current signal. From the experiment results, a conclusion can be drawn that the averaged ionization signal over 20 consecutive combustion cycles is well correlative with the variation of torque, especially in the case of higher torque conditions. The intensity and position of the second peak of this signal are most sensitive to the change of torque.