Modelling and control of a common-rail system for diesel multiple injections

An AMESim model of the injection system has been developed introducing an automatic conversion of an experimental current signal into the force generated by the solenoid. The simulator realizes five multiple injections with different pauses. Using a dedicated current input, with faster rising and falling times, it was possible to realize smaller dwells between injections, optimizing the Bosch Common-Rail (C-R) system timing, without any mechanical modification. Using a commercial injector and an appropriate injection current trend, all the simulation results have been confirmed experimentally. Photographic sequences of a five holes mini-sac nozzle making five consecutive injections at 400, 800 and 1200 bar respectively were taken at ambient pressure and temperature. They showed that both spray penetration and cone angle at all operative conditions are very uniform and stable. Good agreement between experiments and simulations of needle lift has been obtained.