Abstract
The Common Rail System represents nowadays a standard technology used in Diesel Engines. Currently, the third Common Rail generation, featuring piezoelectric injectors, is capable of achieving injection pressures over 200MPa. Being a mecatronic system, it can be fully integrated within the vehicles electronics and programmed to optimize the performance and energetic parameters of the engine. Modern Common Rail systems enable multiple injections, achieving up to four injection sequences in order to achieve amongst others the NOx emission targets. The goal of this paper is to present a calculation method, based on a 1-D simulation tool, for injection timing. The simulated model has been calibrated using experimental data from a diesel prototype engine. The calculation has been done for a multiple injection strategy, with 1, 3 and 4 injection sequences: pre pilot, pilot, main and post injection. The input parameters for the calculation are the geometric dimensions of the Common Rail system, rail pressure, engine speed, injected fuel quantity and the start point of the main injection. The output parameters are the injection durations for all three sequences. The developed calculation method is a fast and cost effective procedure. The results can be used as reference parameters for the programming of the Common Rail controller unit.
Keywords: Injection, Common-rail, Simulation, Timing, Amesim