Spark Ignition System for Direct-Injected Gasoline Two Stroke Engine

The purpose of this paper is to describe a novel ignition system for a direct-injected 2-cycle engine. This system was developed and is utilized on Bombardier Recreational Products' E-TEC™ engine platforms for marine outboard engines and snowmobiles. Traditionally, powersport products have relied on capacitor discharge ignition systems due to the relatively short secondary voltage rise time seen at the plug gap during initial ionization. This characteristic provides a robust spark resulting in ionization at the gap of a contaminated spark plug nose cone. In other words, an ignition spark with a short rise time can fire a fouled spark plug in most instances. The disadvantage of a capacitor discharge system is the relatively short arc duration at the gap. With tighter emission requirements and customer expectations, the combustion quality has become more important than ever. It is well-accepted in the industry that a relatively long arc duration in the gap results in the higher probability of a complete combustion event [1]. Most inductive-type ignition systems provide long arc duration at the gap, but traditionally have fallen short with the short rise time characteristic. This paper will outline an ignition system capable of providing sufficient energy and spark duration while maintaining a short secondary voltage rise time at the spark plug gap. Test results for the system will be included as well as a comparison to other ignition system types.