Towards a Better Understanding of Controlled Auto-Ignition (CAI™) Combustion Process From 2-Stroke Engine Results Analyses
Owing to its inherent high internal residual gas rate in partial load operation, the 2-stroke engine has been the first application to take benefit of the unconventional CAI™ (Controlled Auto-Ignition) combustion process. For a long time, the objective of the different research works on 2-stroke engines optimization was to eliminate its two main drawbacks leading to high emissions of unburned hydrocarbons and a poor fuel efficiency. The first one is the unstable running operation combined with incomplete combustion, especially at light load, The second one is fuel short circuit at medium and full load. From the end of seventies, an approach developed by Onishi from Nippon Clean Engine was to take benefit of an high amount of hot internal residual gases to help auto-ignition of the fresh charge. This solution has been further developed up to the industrialization on 2-stroke engines.