An investigation of optimal fuel injection conditions for the reduction in hydrocarbon emission

Growing international concern about environmental issues in recent years has led to new proposals for strengthening exhaust emission standards and fuel economy requirements throughout the world. To cope with these standards, a reduction of hydrocarbon (HC) emission is the most important thing for the automotive industry to address because HC emission levels are more severe than the emission levels of any other components. In this paper, an apparatus for visualizing the wall film flow in an intake port and a spark plug with optical fibre for detecting the signal from the diffusion flame are developed to investigate the HC formation mechanism. A high-speed camera system is also used to elucidate the correlation between wall film flow and the diffusion flame. Using these methods, the effects of fuel injection systems such as injection direction, spray angle, atomized injector and ambient temperature on HC emission levels are investigated. Consequently, the optimal fuel injection conditions for minimizing the wall film flow and reducing HC emissions are found through this research.