Stratified Scavenging Applied to a Small Capacity Two-Stroke Scooter for the Reduction of Fuel Consumption and Emissions 1999-01-3271
The advantages of high power to density ratio and low manufacturing costs of a two-stroke engine compared to a four-stroke unit make it currently the most widely used engine type for 50cc displacement 2-wheelers. This dominance is threatened by increasingly severe exhaust emissions legislation, forcing manufactures to develop their two-stroke engines to comply with the legislation. This paper describes a simple solution to reduce these harmful emissions in a cost effective manner, for a scooter application. The method of stratified scavenging is achieved by delivering the fuel into the rear transfer passage from a remote mechanical fuel metering device, operated by intake manifold pressure. Air only is delivered into the cylinder from the remaining transfer passages which are directed towards the rear transfer port, thus impeding the fuel from reaching the exhaust during the scavenging process. An experimental evaluation of the concept has shown a reduction in unburned hydrocarbons of 65% and a reduction in brake specific fuel consumption of 20%.
Citation: Mc Elligott, S., Douglas, R., Kee, R., and Glover, S., "Stratified Scavenging Applied to a Small Capacity Two-Stroke Scooter for the Reduction of Fuel Consumption and Emissions," SAE Technical Paper 1999-01-3271, 1999, https://doi.org/10.4271/1999-01-3271. Download Citation
S. Mc Elligott, R. Douglas, R. J. Kee, S. Glover
The Queen's University of Belfast, Ricardo Consulting Engineers
Small Engine Technology Conference & Exposition
Proceedings of the 1999 SAE Small Engine Technology Conference-P-348, SAE 1999 Transactions - Journal of Engines-V108-3