Method for operating a diesel engine

A method for operating a diesel engine having a cylinder, a piston guided in a longitudinally displaceable manner oscillating between an upper dead center position and a lower dead center position in the cylinder, and an injector including an injector valve configured to inject a fuel quantity into the cylinder, the method comprising the steps of:

• compressing combustion air in a compression cycle delimited by movement of the piston from the lower dead center position to the upper dead center position;
• injecting the fuel quantity in a working cycle delimited by movement of the piston from the upper dead center position to the lower dead center position, the injecting step beginning after the upper dead center position;
• abruptly opening the injector valve during the injecting step;
• injecting a pre-injection quantity of fuel during the compression cycle;
• opening the injector valve at a beginning of the pre-injection with a first opening gradient;
• closing the injector valve at an end of the pre-injection with a first closing gradient;
• injecting a main injection quantity of fuel, the injector valve being abruptly opened in the abruptly opening step at a beginning of the main injection with a second opening gradient;
• and
• closing the injector valve at an end of the main injection with a second closing gradient;
• wherein the second opening gradient is greater than the first opening gradient.