Long-life traveling spark ignitor and associated firing circuitry

Abstract

An ignitor and associated electronics for igniting a combustible mixture in a cylinder of an internal combustion engine are described. The ignitor includes at least two spaced-apart electrodes that define a discharge gap. The space between the electrodes is substantially filled with a dielectric material. The dielectric material is spaced-apart from at least one of the electrodes to provide an air gap over which an initial voltage breakdown between the electrodes will occur. The air gap serves to vary the location of the initial breakdown and as a barrier to a short circuit between the electrodes due to carbon and/or metal deposit buildup on the dielectric material. The associated electronics provide a first potential between the electrodes that generates a plasma between the electrodes. Then the volume of the plasma is increased by the application of a second potential that creates a current through the plasma. The plasma, as well as the current passing through, is swept outward due to the interaction of Lorentz and thermal expansion forces with the plasma. Also described are relative orientations of the electrodes that lead to greater plasma formation.