Individual Cylinder Combustion control based on Real-Time Processing of Ion Current Signals

The paper presents the main results of a research activity focused on the analysis, development, and real time implementation of a closed-loop, individual cylinder combustion control system, based on ion sensing technology. The innovative features of the proposed control system consist of extracting combustion quality related information from the ion current signal, and of using such information, together with pre-defined look-up-tables, for feedback control of the spark advance throughout the entire engine operating range. In particular, the ion current signal processing algorithm that is carried out in real-time, initially determines whether knocking is affecting or not the actual combustion process. Based on such evaluation, the closed-loop spark advance controller uses different signal processing algorithms to continuously determine individual cylinder spark advance deviations with respect to a pre-defined, base spark advance look up table, common to all the engine cylinders, and to store them in the Electronic Control Unit memory. The main result is therefore a spark advance controller that is continuously able to adapt its actuations both to engine/components variations (either due to ageing or to manufacturing component dispersion), as well as to varying external conditions (fuel quality, air temperature,…), in order to maximize torque production (or overall efficiency), cylinder by cylinder and combustion by combustion, even if the specific operating condition is affected by knock insurgence. The proposed control strategy has been successfully tested on a V12 6.0 liter and on a V12 6.2 liter high performance engines, and it is now part of the control system of V12 6 liter and V8 4 liter Ferrari engines.