Direct Injection Gasoline Engines - Combustion and Design

The charge motion controlled combustion concept for SI engines with direct fuel injection exhibits an excellent fuel economy and emission potential in comparison with other DI combustion concepts. It realizes a stable combustion behavior all over the engine map. Because injection and ignition timing has little bearing on emission and ignition safety, the new concept can be easily applied under DI specific operational conditions. The combination of fired engine tests and optical investigations with CFD calculations enables an efficient process optimization under the boundary conditions as imposed by the respective design. The high EGR tolerance enables a large reduction of NOx emission, which is the expected basic requirement to meet future emission standards. In addition to favorable part load behavior, the new combustion concept also displays all of the characteristics for a good full load behavior. Its compact central combustion chamber design perfectly meets the requirements of homogeneous operation. Further, the use of roller finger followers enables a favorable cylinder head design, meeting all requirements of the combustion concept and ensuring minimal valve train friction.