Improvement of Fuel Economy Using a New Concept of Two-Stroke Gasoline Engine Applying Stratified-Charge Auto-Ignition 2009-28-0009

Aiming for improving fuel economy of vehicles, a new two-stroke gasoline engine utilizing stratified-charge auto-ignition has been designed and tested. The engine concept was to switch the combustion mode according to the engine operating load and speed, i.e., homogeneous-charge spark-ignition for the high-load range, homogeneous-charge auto-ignition for the mid- to low-load range, stratified-charge auto-ignition for the low-load low-speed range, and stratified-charge spark-ignition for idling. Using this engine concept, an experimental two-stroke engine was successfully operated free of irregular combustion throughout the range of operating loads. For small motorcycle applications, a great improvement in fuel economy and exhaust emissions was estimated from the experimental data.