Needle lift of fuel injector nozzle and pressure curve in the cylinder without pilot injection
1 Combustion pressure in the cylinder
2 Needle lift
3 TDC (Top Dead Center)
4 Needle lift for simple main injection
5 Crank angle
In the case of diesel engines with a distributor-type fuel injection pump (for example in the Transit 2000.5), the fuel injection on the pump-side is via simple main injection.
The fuel is then injected mechanically into the combustion chamber by the injector nozzles in two seamlessly integrated stages (two-spring nozzle carrier principle).
In the pressure curve, the combustion pressure increases only slightly in the phase before TDC, corresponding to compression, but increases very sharply at the start of combustion.
The steep pressure rise intensifies the combustion noise.