Conventional Fuel Injection System in Two-Stroke Engines

摘要

Carburetted 2-stroke engines are a worldwide pandemic. There are over 50 million 2-stroke cycleengines in Asia alone, powering motorbikes, mopeds, “three-wheelers”, “auto-rickshaws”, “tuk-tuks”, and“tricycles”. These carbureted 2-stroke engines are characterized by high levels of hydrocarbon (HC), carbonmonoxide (CO), and particulate matter (PM) emissions. Direct injection is a technology that has shown agreat ability to reduce these emissions while at the same time improve fuel economy. A prototype kit has beendesigned for use in retrofitting existing carbureted two-stroke engines to direct injection. The kit was designedfor use on a TVS 50; a motorcycle from the INDIA that is commonly used as a transportation. It is however, arelatively common engine design and TVS manufactures similar models for sale all over the world. Theconventional fuel injection system kit incorporates the Orbital air blast direct injection system. This injectionsystem has been implemented in TVS 50. The design involved replacing the existing cylinder head with onedesigned to incorporate the direct injection valves as well as a modified combustion chamber. An externalcompressor was added to supply compressed air to the system. The carburettor was refined with a throttle bodyoutfitted with a position indicator, and an encoder system was added to provide speed and position feedback tothe engine control unit (ECU). Once design and manufacture of the system was complete, it was installed onthe motorcycle. The motorcycle was then mounted in a low inertia eddy current dynamometer test cell forcalibration. Calibration was done on the dynamometer for power and engine performance. The system wasalso tuned in real world road tests for drivability. When calibrations were complete emissions and fuelconsumption measurements were taken for the vehicle. The results showed an 88% reduction in hydrocarbonemissions and a 72% reduction in carbon monoxide emissions versus the baseline engine, while at the sametime virtually eliminating visible smoke. The CFI system also showed a 32% increase in fuel economy, and hadsimilar to better performance than the carbureted engine. The CFI system also showed improved cranking andidling characteristics over the carbureted engine.