This paper reports on a spark plug electrode geometry which promotes spark discharge on the periphery of the electrodes. A notched center electrode promotes reduced heat loss from the flame kernel and results in a stronger kernel, with subsequent faster growth.
Some typical operating parameters affected by the approach were examined. Test data are presented which demonstrate the potential for improving ignition of lean air/fuel mixtures, cold weather performance, and fuel consumption, while maintaining durability characteristics comparable to conventional spark plugs.
The ignitability and durability tests were carried out on a stock V8 spark ignited gasoline engine in an engine dynamometer test cell. Varying the mass air/fuel ratio under idling conditions indicated that the test plug can idle significantly leaner than the baseline (conventional electrode) plugs while maintaining similar misfire characteristics. Durability testing consisted of 60 hours operation at rated power. The initial indication is that this approach is comparable to the baseline spark plugs in terms of sustaining required firing voltage and gap growth.
Cold performance and fuel consumption tests were carried out on a stock light duty van with a V8 spark ignited gasoline engine, running on a chassis dynamometer. The test plugs exhibited superior antifouling performance under simulated cold weather starting and stopping conditions. Fuel consumption tests indicated the potential for improved economy under idling conditions.