Study on a Stratified Charge Spark Ignition Automotive Engine

Abstract

This paper is a synthesis of some theoretical and experimental researches done during several years, in order to find the most efficient and simple solutions for a spark ignition engines that function on inhomogeneous poor mixtures. There are numerous stratification solutions for the mixture, both in the unitary and divided combustion chambers. We have applied the divided combustion chamber concept, using a flame jet in order to ignite the lean air-fuel mixture, in the main combustion chamber. The secondary or auxiliary combustion chamber, placed inside the cylinder head was fueled by direct fuel injections, with a rich mixture.

Generally, gasoline direct injection imposes higher pressures than injection into the inlet manifold. Meanwhile, the injection pump should have a long service life while operating at high speeds. As a matter of fact, injection pump service life was one of the factors that have restricted the use of direct injection. Using mainly, the direct injection of gasoline, based on our own equipment we studied this procedures to producing and igniting the poor mixtures on an experimental engine. In the meantime, three types of spark plugs were tested.

The results experimental obtained on the test bed with this engine in homogeneous poor mixtures confirms the initial premises and proves the possibilities of the stratification procedure that was used.

The article also contains the experimental results, as the reduction of the specific fuel consumption for small partial loads, a domain in which the car engine is often used and the reduction of some noxious emissions, especially CO and HC.