Abstract
A recent trend in the making of automotive engines, where high efficiency and low emissions need to be considered, is to mount multiple parts around the motor in order to improve overall engine efficiency. As a result of modern technology, the engine head and surrounding space have an excessive amount of parts. To accommodate the congested engine compartment, it is desirable to reduce the size of the spark plug. Small spark plugs have the problem of poor resistance to carbon or fuel additive fouling and are subject to side sparks if carbon or fuel additive fouling occurs. This results from a reduced insulating gap between the center electrode and the housing achieved by reducing the size of the spark plug. By using visualization of the spark area and electric field strength analysis, we have conducted studies on insulator temperatures and spark behaviour in search of the optimal specifications. By doing so a new spark plug has been successfully developed, which performs as well as if not better than the conventional plug, even though its thread size has been reduced from M14 to M10.
Keywords:Spark plug, Miniaturization, Fouling resistance, Carbon, Fuel additive