Abstract
KEYWORDS
4 stroke small engine, EMS, Carburetor, Port Injection, SCV, Emission.
ABSTRACT
Recently, engine management system (EMS) for automotive engines has been applied to motorcycle to meet the increasing need for enhanced fuel economy and emission characteristics. In this context, electronically controlled injection system has been preferred instead of carburetor system for fueling. In this paper, a new EMS system for small engine was developed. Port injection system was adopted instead of carburetor system, and the throttle body was modified. Also other components, such as ignition system and the shape of intake port, were optimized to get better performance. The experimental results of new EMS system showed better fuel consumption rate and emission characteristics compared to the carburetor system. In full load condition, maximum 14% reduction of brake fuel consumption was obtained with the new EMS. Due to enhanced control of air fuel ratio, amount of HC emission decreased, even though NOx increased. In the condition at part load, EMS with swirl control valve (SCV) showed lower fuel consumption rate and low HC emissions compared to that without SCV. The NOx emissions increased due to enhanced burning rate, but the exhaust gas temperature decreased due to enhanced heat transfer to the cylinder wall.