DEVELOPMENT OF A DIRECT INJECTION TWO-STROKE ENGINE FOR SCOOTERS 2001-01-1782
The new European legislation on two-wheeler pollutant emissions has forced two stroke engine manufacturers to study the direct fuel injection (DI) technology. The Piaggio “ET2 Injection” was the first DI engine in production, using the FAST system (Fully Atomized Stratified Turbulence) applied on a 50 cm3 engine.
Within the framework of the DOLCE project (Development Of innovative Low pollutant, noise and fuel Consumption two stroke spark ignition Engines for future vehicles for individual urban mobility) coordinated by Piaggio and supported by the European Commission, a 125 cm3 direct injection 2-stroke engine was developed. This paper presents the engine-related part of this work, which was concluded in March 2000.
The engine is equipped with the FAST system and the fuel metering is performed by means of a low-pressure electronic fuel injection system integrated in an Engine Management System (EMS) specially developed for this type of application.
Preliminary thermodynamic calculations were made for both one-dimensional as well as three-dimensional flow behavior. The layouts of the gas exchange parts (air cleaner, throttle body, reed valve, scavenge ports, exhaust ports and exhaust system) as well as the combustion system (combustion chamber, injector, spark plug) were optimized.
After a fine tuning of the EMS, the roller bench measured results produced values lower than those required by the future Euro 2 emission limits. The performed road tests confirmed a good driveability and a very flexible vehicle behavior in transient operation.