Abstract
The reduction of engine out emissions has been more important to solve the global warming problem. Enhanced intake charge motion of the engine has an effect to the volume efficiency, combustion stability and stratification of a fuel in the cylinder. This effect can achieve the reduction of engine out emissions. In this study, emission characteristics at cold transient condition and idle condition with different intake charge motions by port masking schemes in the gasoline engine was investigated. Port masking schemes were modified with different intake flow way shapes and sections to make various amount of swirl and tumble flow. Time resolved in-cylinder HC and NOx emissions were measured by the fast response gas analyzer to examine their formation mechanism. Continuous distribution of PM (Particulate Matter) was also analyzed by fast PM analyzer (DMS500, Differential Mobility Spectrometer). As a result, in-cylinder HC decreased with improvement of combustion efficiency due to the enhanced intake charge motion. However, charge motion improvement caused an increment of combustion temperature thus in-cylinder NOx increased consequently. In addition, the application of port masking schemes lead to an enhancement of the combustion stability and PM emission decreased by this effect comparing with a base port. It was confirmed that enhanced intake charge motion has an influence on the PM reduction at idle speed condition after cold start.
Keywords: Particulate matter, Particle size distribution, Fast response FID, Fast response CLD, Differential Mobility Spectrometer, Port masking