Concept of Interactive Development of a GDI System with High-Pressure Modulation

The potential of fuel direct injection regarding the performances of a SI engine is transformable in significant advantages only by an accurate control of the internal air/fuel mixture formation. A main control element is the adaptability of the injection law, respectively of the spray characteristics to the thermodynamic conditions within the combustion chamber for different load and speed. This paper presents a method for the effective implementation of GDI techniques to SI engines, which is exemplified by a system with injection law modulation by pressure. The method is based of the interactive optimization of the processes within the combustion chamber respectively within the injection system, by a feed-back strategy between separate numerical simulations of both systems. For both modules the calibration is ensured by appropriate experimental analysis. The design and the performances of a direct injection system developed with this method for automotive SI engines are presented as application example.