ABSTRACT−Injection rate shape control is one feature of a diesel fuel injection system that is strongly desired at this
time. In the conventional common rail system, it is difficult to control the injection rate since the fuel pressure is constant
during the injection period, resulting in a nearly rectangular rate shape. In order to look into possible injection
modulations, injectors equipped with standard and geometrically modified control valves were investigated in detail by
means of computer modelling and simulation. Experiments were carried out to validate the feasibility of such a shaping.
The results of this study show a noteworthy dependence of the fuel rate on geometrical modifications in the piloting stage
of the injector
