Search Results

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 size spark plugs have the problem of poor resistance to carbon fouling and are subject to side sparks if carbon 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 flame growth and electric field strength analysis, we have conducted studies on insulator temperatures and spark behaviors in search of the optimal specifications.

In the field of automotive gasoline engines, new products aiming at greater fuel economy and cleaner exhaust gases are under development with the aim of preventing environmental destruction. Severe ignition environments such as lean combustion, stronger charge motion, and large quantities of EGR require ever greater combustion stability. In an effort to meet these requirements, an iridium plug has been developed that achieves high ignitability and long service life through reduction of its diameter, using a highly wear-resistant iridium alloy as the center electrode.(1)(2) Recently, direct injection engines have attracted attention. In stratified combustion, a feature of the direct injection engine, the introduction of rich air-fuel mixtures in the vicinity of the plug ignition region tends to cause carbon fouling. This necessitates plug carbon fouling resistance.