1 Top dead center
2 Pressure curve without pilot injection
3 Combustion pressure in the cylinder
4 Pressure curve with pilot injection
5 Injector needle lift
6 Injector needle lift for pilot injection
7 Injector needle lift for main injection
8 Crank angle
The pilot injection brings about a preconditioning of the combustion chamber and has the following effects on this:
• The compression pressure is raised slightly by the initial reaction or partial combustion process, as a result of which the ignition lag for main injection is shortened and the combustion pressure rise is reduced (softer combustion).
These effects diminish the combustion noise and the NOX emission.
