Gasoline i.c. engine with spark-ignition and auto-ignition in the same cylinder

摘要

A method of operating a gasoline internal combustion spark ignition engine is disclosed, which comprises first separating the gasoline into a lighter vapour fraction and a heavier liquid fraction. The two fuel fractions are supplied separately to the combustion chambers of the engine in such a manner as to achieve stratification of the charge in each cylinder at the instant of spark when the engine is operating at part load. The stratified charge includes a first ignitable mixture cloud lying in the vicinity of spark plug at the instant of the spark and containing the heavier liquid fraction of the gasoline, and a second mixture cloud lying at a distance from the spark plug at the instant of the spark and containing the lighter vapour fraction of the gasoline. The fuel-to-air ratio and the composition of the fuel in the second cloud are such that the second cloud undergoes auto-ignition subsequent to the instant of spark ignition of the first cloud, the auto-ignition being brought about by the increased temperature and pressure resulting from the burning of the fuel in the first cloud.