This article covers an investigation into the potential of a corona ignition system in comparison with a conventional ignition system for the HCCI combustion process. As a first step, a variation in the ignition timing was carried out for a representative engine operating point. Both ignition systems proved to be principally capable of influencing the autoignition process. However, equal ignition timings resulted in significantly advanced MFB50 timings for the corona ignition system compared with the conventional ignition system. The effect of varying the ignition energy was investigated next. For this purpose, the energy stored in the ignition coil was varied using the conventional ignition system. However, no significant differences could be found between the minimum and maximum ignition energies that could be realized with the ignition system employed. The dependences for the corona ignition system turned out to be different. The corona ignition system allowed the combustion timing to be influenced both by an increase in the ignition voltage and by an extension of the ignition duration. These measures affected the combustion in two positive ways. On the one hand, retarded IPs were possible for identical MFB50 timings with an increase in the supplied energy. On the other hand, for identical MFB50 timings the STDMFB50 decreased with the corona ignition system. Further investigations were carried out on the sensitivity of the ignition systems with respect to the trapped RGF. In this context, the corona ignition system proved to compensate more robustly for the changed boundary conditions because of a significantly leaner mixture. Finally, this increased robustness could be explained by the increased stability of the initial flame kernel formation observed in an optically accessible engine. Overall, the investigations proved that the corona ignition system offers significant benefits for the HCCI combustion process in terms of the combustion stability and MFB50 control in comparison with a conventional ignition system. Owing to its functional principle, the corona ignition system allows a significantly increased initial fuel conversion rate. It is thus possible to condition the unburned mixture fraction in the combustion chamber to the required temperature for autoignition even with comparatively late ignition times. The reason for this behaviour can be found in the larger flame kernel originating from the initial inflammation. With a conventional ignition system, on the contrary, similar effects in the autoignition timing can only be reached by a significant increase in the spark advance. However, this increases the duration of the initial deflagrative combustion period, which is subject to numerous influencing parameters. This, in turn, drastically increases the cyclical variations in the inflammation process and reduces the combustion stability.


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    Title :

    Investigation of the potential of corona ignition to control gasoline homogeneous charge compression ignition combustion


    Contributors:
    Suess, M. (author) / Guenthner, M. (author) / Schenk, M. (author) / Rottengruber, H.S. (author)


    Publication date :

    2012


    Size :

    12 Seiten, 13 Bilder, 1 Tabelle, 22 Quellen




    Type of media :

    Article (Journal)


    Type of material :

    Print


    Language :

    English