Two-stroke cycle gasoline engine

摘要

A two-stroke cycle gasoline engine including at least one two-stroke cycle uniflow scavenging power cylinder-piston assembly which has a scavenging port configuration which consists of first, second, and third scavenging port configurations which are successively uncovered by the power piston as it moves from its top dead center to its bottom dead center, wherein the first scavenging port configuration has a substantially smaller opening area than the second or the third scavenging port configuration, and the first and the second scavenging port configurations give substantially stronger swirl to fuel-air mixture discharged therefrom than the third scavenging port configuration, which gives substantially no swirl to fuel-air mixture discharged therefrom, and the first and second port configurations are closed when the engine is operating at relatively low load above idling and below a predetermined delivery ratio, such as 0.4.