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A high-frequency electrical resonance-based ignition concept is in development to replace conventional spark ignition functionality for gasoline engines employing various types of fuel injection methods. The concept provides the benefit of a continuous discharge phase and the electrical power of the discharge can also be adjusted to the needs of the combustion conditions. This concept employs an alternative method of generating high voltages, using inductors and capacitors trimmed such that the supplied energy steadily increases the output voltage. This configuration is widely known as Tesla transformer and has been engineered to operate in a modern gasoline engine combustion environment. This development allows very high break down voltages to be generated and the power into the spark itself can be influenced.

The success of stratified combustion is strongly determined by the injection and ignition system used. A large temporal and spatial variation of the main parameters - mixture composition and charge motion - in the vicinity of the spark location are driving the demands for significantly improved ignition systems. Besides the requirements for conventional homogeneous combustion systems higher ignition energy and breakdown voltage capability is needed. The spark location or spark plug gap itself has to be open and well accessible for the mixture to allow a successful flame kernel formation and growth into the stratified mixture regime, while being insensitive to potential interaction with liquid fuel droplets or even fuel film. For this purpose several different ignition concepts are currently being developed. The present article will give an ignition system overview for stratified combustion within Delphi Powertrain Systems.