From glow tube to corona – challenges to the ignition systems of future SI engines

Whether being „the problem of the problems“, as Carl Benz called it, or the central, even eponymous component: The challenges as well as the chances of the ignition system have accompanied the past 150 years of SI engine development.Within this process the activities focused for a long time on the development of lowcost, robust and as maintenance-free as possible ignition components to assure, in context with the developments of the injection systems, a reliable engine operation under all climatic conditions. With rising awareness towards exhaust emissions and for this reason increasing legislative requirements, the functional demands on the ignition process increased considerably since the 1970’s. The legislative restrictions with respect to the emissions of pollutants – gaseous as well as particulate emissions- are continuously rising ever since. This is accompanied by the necessity of a continuously rising engine efficiency to meet the steadily more severe CO₂ fleet emission limits.The adaptations of the SI-engine combustion strategies as a consequence of these requirements, such as charge dilution or gas exchange strategies, often significantly impede the inflammability of the mixture. Thus, besides the measures for the generation of a higher level of charge motion, it is especially the optimization regarding the ignition systems, which allows an extension beyond the currently valid tolerance limits. Hereby, besides the stationary demands of the engine map, especially the necessities of the transient engine operation as well as the worldwide performance compliance have to be taken into account.Within our presentation the potentials as well as the limitations of various ignition innovations are discussed. We will look upon optimizations of the classical spark ignition, referring always to today´s serial solution, as well as upon alternative, spacious ignition systems. Besides the evaluation of the stationary potentials, especially the transient and realization relevant aspects will be illustrated. The resulting demands and potentials towards an automotive industrialization will be discussed.