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We have achieved injection quantity range enhancement by using the current waveform control technique for direct injection (DI) gasoline injectors. In this study, we developed an injection quantity simulator to find out the mechanism of non-linear characteristics. We clarified the non-linear production mechanism by using the simulator. This simulator is a one-dimensional simulator that incorporates calculation results from both unsteady electromagnetic field analysis and hydraulic flow analysis into the motion equation of this simulation code. We investigated the relation between armature and the injection quantity by using the simulator. As a result, we clarified that the non-linearity was produced by the bounce of the armature in the opening action. Thus, we found that it is effective to reduce the armature bounce to improve the linearity of the injection quantity characteristics.

The demand for clean energy efficient transportation is rapidly increasing to meet greenhouse gas emissions reduction and promote sustainability. Gasoline direct injection engines (GDI) have high thermal efficiency thus low greenhouse gas emissions compared with conventional port fueled engines. However, during cold start conditions GDI engines produce harmful emissions, including nitrogen oxides, hydrocarbons, and particulate matter. Thus, high pressure fuel system development for direct injection of gasoline is being conducted to reduce emissions during engine cold start. This paper summarized the effect of high fuel pressure and multiple injections on cold catalyst light-off strategy for rapid heating of the catalyst. Experiments were carried out using light-duty four-cylinder engine at cold catalyst light-off conditions with coolant temperature at 30 °C.