Electronic fuel injection controller for natural gas vehicle motorcycle

Abstract

Smaller vehicles are a major source of both air pollution and congested roads. The use of natural gas is recommended by the United States Federal Clean Air Act Amendments of 1990, because it is environmentally friendlier than petrol engine. Therefore, this thesis presents the design and development of a low cost electronic fuel injection (EFI) for natural gas vehicle (NGV) motorcycle. The design consists of signal conditioning, microcontroller systems and the injector drive circuit. The output of this research is a prototype of EFI which has the capability to control output engine based on the given mapping table. Two types of mapping table are used to generate pulse width and timing injection. The first is injection pulse width corresponding to the rotation per minute (RPM) and manifold absolute pressure (MAP) and the second is RPM corresponding to encoder angle position. Both of these mapping tables are accessed concurrently within a single programming which reduces the use of extra microcontroller and memory. The EFI enables the mixing and combustion with 17.2:1 (by mass) air to fuel ratio (A/F). In injector measurement, the first large voltage of 35 V spike at 1.8 msec corresponds to the reduction in coil current from 4.5 A to 1 A. The pulse width resulted from the theoretical calculation can be used for the engine experiment between 3000 RPM and 8000 RPM. This is due to the air density value taken by the used formula.