| 摘要 |
The invention relates to a method for operating a direct-injection Diesel engine that comprises at least one piston, reciprocating in a cylinder, whereby the internal combustion engine is operated in such a manner that the fuel is substantially combusted at a local temperature below the Nox formation temperature and at a local air ratio above the soot formation limit. Fuel injection is started in a crank angle range of between 2 DEG before the upper dead center and up to approximately 10 DEG after the upper dead center of the compression phase and exhaust gas is returned, the exhaust gas return rate amounting to approximately 20 % to 40 %. The aim of the invention is to achieve particularly low nitrogen oxide and soot emissions. For this purpose, at least one piston (27) is provided with a squish area (34) and a toroid piston recess (28) and a necking (29) in the transition area between the squish area (34) and the piston recess (28). When the piston (27) moves upward a squish flow is produced which flows from the outside to the inside of the piston recess (28) and a turbulent swirl (43, 43a) within the piston recess (28) is initiated. At least the major portion of the fuel is injected into the toroid piston recess (28) and is transported along the piston recess wall (31) and/or the piston head (32) while at least partially evaporating. |
