Experimental Study On The Ambient Temperature Field Of FAI EFI System Applied To Motorcycles

Confronted with the increasingly severe air pollution and energy shortage problems, Chinese motorcycle manufacturers have begun to adopt the electronic fuel injection (EFI) system to replace the carbureted fueling system for reduced pollutant emissions and improved fuel economy. The Free Armature Injection (FAI) system has been developed to meet the demands of the motorcycle industry. The FAI system features simple and compact construction, low power consumption, non-sensitivity to fuels with different qualities, and minimum modifications to the original vehicle, etc. Its successful application to four-stroke motorcycles proves it to be a simple and highly efficient EFI solution.The unit-type FAI injector which only employs low pressure fuel lines, however, suffers from the"bubble"problem when operated under high engine temperatures, resulting in inaccurate fuel metering. Consequently, to further improve the performance of the FAI system, the temperature of the injector and its surrounding fuel pipes must be effectively reduced.This thesis reports the experimental study and analysis of the inside-the-vehicle temperature field when the motorcycle is equipped with the FAI system.A temperature-data-acquisition system was developed. Temperature distributions of the EFI components and the environment were acquired, then displayed on the screen of and saved on the PC through a serial interface; analysis was then made based on the obtained temperature information. Evaluation of adaptability of the FAI injector and the fuel line to different type of vehicles (water-cooled and air-cooled, motorcycles and mopeds) was conducted. The conclusions were used to make an optimal design of the structure and the settlement position of the FAI injector when applied to a specific vehicle. Validation experiments were also performed, and the results demonstrated that these improvements had effectively eliminated the fuel bubble problem.