Development of carburetors and element parts of fuel injection system for motorcycles

摘要

With the increasing requirements of environmental conservation in recent years, reduced exhaust emissions and increased fuel-efficiency are in high demand for smaller size motorcycles popular in the Asian region. In order to meet such demand, the optimum design of the fuel supply system is the most effective method. In the carburetor, the core component of the fuel supply system used on a majority of current models, a 25% improvement in the accuracy of air-fuel ratio fluctuation, as well as a 15% reduction in size, have been achieved in comparison with past models. On the other hand, in fuel injection systems, the use of which is gradually expanding, it is essential that the components be highly functional with high performance, while at the same time being of a compact size. In regards to the injector, optimum spray form and a 30% reduction in size have been realized by utilizing injection simulation techniques. As for the fuel pump, a unit capable of operating with an electrical current of less than 1 amp has been developed by optimizing the design of the pump rotor. For the throttle body, the number of sensor components has been reduced by 21 while at the same time stable control at minute airflow volumes has also been achieved. In regards to the ECU, with the use of integrated-function custom IC components and high-density surface mounting, both a reduction in size and also an increase in possible function range have been realized. As a result of these activities, system components to constitute a fuel injection system easily installed in and suitable for the wide range of engine frames and engine characteristics of small size engines have been developed.