The injector of the Common Rail System contains the injection nozzle, a solenoid valve plus the hydraulic and electrical connections to trigger the nozzle module. An injector connected to the rail via a short high-pressure line is installed in each engine cylinder.The electro-hydraulic servo system in the injector receives control impulses from the EDC (Electronic Diesel Control) to open and close the nozzle module. It is triggered by a solenoid-valve. The short switching times of the solenoid permit pilot, main and secondary injections. In this way, fuel combustion can be designed to be efficient and clean at all operating points.In order to reduce the load on the high-pressure pump and to permit additional freedom when shaping the injection discharge rate, Bosch has developed innovations such as an injector with reduced leakage and an injector with a pressure converter that continues to further pressurize the fuel within the injector.
INJECTOR NOZZLE FUNCTION:
The injection nozzle consists of the nozzle body the cone of which protrudes into the combustion chamber. The injection orifices through which the fuel is injected are bored in the nozzle cone. The number, configuration, length and diameter of these injection orifices permit the shape of the injection spray to be formed in a way that is ideally matched to the engine cylinder.Inside the nozzle body is the nozzle needle which, when closed, blocks the injection orifices. For fuel injection, the nozzle needle is raised by the hydraulic servo system of the injector so that the injection orifices are opened. The faster the nozzle needle can be opened and re-closed, the more precisely the injection rate can be controlled.The injection rate and the shape of the injection spray have a decisive influence on fuel consumption and raw emissions from the engine.
INJECTOR PUMP FUNCTION:
The task of the high-pressure pump is to pressurize the fuel in the amounts required for the entire engine operating range. To do this, it constantly feeds fuel into the high-pressure accumulator (rail), thus maintaining the system pressure. The fact that pressure generation is not linked to engine speed means that the pressure required is already available at low engine speeds.Injection nozzles for diesel engines inject the fuel into the combustion chamber, atomize it and seal the combustion chamber by means of the nozzle needle. In the Common Rail System, the injection nozzle is part of the injector.