A Study on a Spark Plug for Charging of Stratified Mixture in a Local Area

This study proposes a new stratified charge system for low emission and ultra lean burn. Combustible mixture was induced around sparkplug using a spherical piston cavity and up-right straight port in the general method of stratified charge. A new method of stratified charge is proposed using an injector-type spark plug in this study. This system injects fuel of extremely small quantities and ignites the mixture around the spark plug gap. The injector-type spark plug was fixed in a visualized constant volume chamber. The combustion characteristics were compared with that of the conventional ignition method. The combustion characteristics and lean combustible limits were examined, and then a photograph of flame luminosity was taken by a high speed camera with an equivalence ratio. As a result of this study, in the case of using the injector-type spark plug, initial flame propagation speed increased and total combustion period was reduced in the over lean burn in the same equivalence ratio. These phenomena occurred clearly under the conditions of low equivalence ratio. Furthermore, the lean combustible limit of the mixture was extended by using the injector-type spark plug.