1989-02-01

A New Spark Ignition System for Lean Mixtures Based on a New Approach to Spark Ignition 890475

The current perspective on spark ignition is that of an electrical energy source which is introduced into a combustion chamber to ignite a combustible mixture by electrically breaking down a spark gap and delivering electrical energy (current) to the gap. Topically, the spark gap is made up of two very closely spaced electrodes (of a spark plug) which are exposed to the mixture. Such a perspective is far too limited in that it ignores the electrical plasma nature of the initial flame and the influence that the local electric field and spark discharge have on the growth of the flame. Specifically, it ignores the development of the spark and hydrocarbon flame discharges as coexisting electrical phenomena competing for the electrical energy that is supplied by the ignition system. In so doing, it fails to consider or supply the required level and quality of energy to the mixture, rendering ignition of little value except in mixtures which are ordinarily easy to ignite.
On the other hand, a theory has been developed for including these phenomena in what is an expanded view of spark ignition. Moreover, an ignition system has been developed which implements the features of this theory. This ignition system is highly effective in igniting the very lean to ultra-lean mixtures necessary to make the lean burn engine practical to provide simplified emissions' control with excellent fuel economy.

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