Features of an Atkinson Two-Stroke Engine

A two-stroke Atkinson cycle engine is described. The engine has uniflow stratified mixture scavenging with a variably phased spherical rotary valve in the cylinder head and exhaust ports in the cylinder wall. These features combined in this configuration result in reduced fuel consumption, higher specific power output, less vibration, and smooth part load operation albeit increased size and cost compared to simple two-stroke engines used in power tools.