Electronically Controlled High Pressure Unit Injector System for Diesel Engines

To achieve the future emissions regulations with low particulate and No_x levels, both the engine combustion system and the fuel injection equipment will have to be improved. For the fuel injection equipment, high injection pressure and variable injection timing as a function of engine speed, load, and temperature are of great importance. BOSCH is developing two different solutions:

• electronically controlled unit injector and single cylinder pump systems,
• high-pressure inline pumps with control sleeve and electronic control.

This paper describes:

• the unit injector and its high-pressure solenoid valve
• the requirements for the mounting of the unit injector in the engine
• the low-pressure system
• the electronic control unit and the metering strategy