High Frequency Ignition System for Gasoline Direct Injection Engines 2011-01-1223
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. Several new innovations in the areas of high frequency, high current, and high voltage electrical contacts were required, as well as new encapsulation methods and electronic controls to give good performance as an automotive ignition source.
The circuit topology for the concept is called a capacitive-loaded, quarter-wave transmission line and the resonating structure is dominated by a dedicated high frequency spark plug and a single wound coil. The electronic source which supplies this passive structure underwent several iterations before a preferred electronic solid state driver-amplifier configuration was identified.
The new ignition system concept and the latest engine results will be presented. The chosen design trade-offs will be discussed.