DI Diesel Emission Control by Optimized Fuel Injection

Control of NOx and PM from diesel engines is a key for enlarging its application in transportation field. To achieve this, many improvements have been done, for instance, the introduction of highly flexible common-rail injection system and cooled EGR system with advanced control strategy. In order to meet more stringent emission regulations in near future, research and development activities have been carried out energetically in the world. In this paper, a low emission combustion strategy is realized by combination of common-rail and cooled EGR. First of all, low soot combustion is approached by optimizing pilot and main injection, in which pilot is controlled to eliminate hot flame. Then, once low soot combustion achieved, higher EGR can be used to reduce NOx. As the application of this combustion concept, two diesel powered vehicles are tested on chassis dynamometer for both European and US regulations, the results confirmed that both US Tier2 Bin10 and half of EU Euro IV can be achieved without active NOx and soot after-treatment.