GASOLINE INTERNAL COMBUSTION ENGINE

摘要

The invention relates to a gasoline internal combustion spark ignition engine having a fuel fractioning system that separates the gasoline fuel by boiling point into at least two, preferably three, fractions. The different fuel fractions are separately supplied to the combustion chamber of the engine in such a manner as to achieve in each cylinder a two-zone stratification of the charge at the instant of spark when the engine is operating at low and medium loads. The two-zone stratification consists of two contiguous mixture clouds, a first of the two clouds lying in the vicinity of the spark plug and containing a higher concentration of the higher boiling point fuel fraction than the second cloud lying at a distance from the spark plug. The average composition of the fuel and the fuel-to-air ratio 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 of the second cloud is brought about by the increased temperature and pressure resulting from the advancing flame front in the first cloud and the timing of the auto-ignition of the second cloud occurs at a predetermined time delay after the instant of spark ignition of the first cloud.