Combustion Pressure Deviation at Intake and Exhaust Throttling in DI Diesel Engines

Abstract

Throttling of intake and exhaust ports in DI diesel engines are often used to get high EGR rate and to rise exhaust gas temperature at light load. However, cylinder-to-cylinder deviations in the combustion and the exhaust emission are not clear during the throttling process. This study attempts to investigate correlations between cylinder-to-cylinder deviations in the fuel injection characteristics and combustion and THC emission when intake and exhaust ports are throttled at idling. It is concluded that cylinder-to-cylinder deviations in THC emissions are larger at intake port throttling, but is not significant at exhaust port throttling. Cylinder-to-cylinder deviation in combustion is responsible for the deviations in THC but that is not dominating factor. Deviations in the in-cylinder conditions such as carbon deposits and in-cylinder gas flow are thought to play a larger role in THC deviations.