An Experimental Characterization for Injection Quantity of a High-Pressure Fuel Injector in GDI Engines

In GDI engine applications, high-pressure (H.P.) injectors typically require to be designed to be capable of rapid response for GDI engines in order to be driven in the rapid response with respect to magnetic actuators, allowing for example more precise air-fuel ratio control in the GDI engines. The H.P. fuel injector is a highly dynamic component requiring careful voltage and pressure input modulation to achieve the required fuel injection quantities of GDI engines. The accurate fuel injection curves are a key influence for this technology, therefore will require the estimation of the fuel flow rate to be realized. In this paper, a PIC microchip for programming injector drive circuits is implemented to improve the performance of a H.P. fuel injector and tested to verify its feasibility. In the proposed injector drive circuit, powers MOSFETs directly control the charging/discharging current by a dsPIC30F4011 microchip. Design and analysis of the proposed injector drive circuit are presented. Next, effects of total pulse width, injector supply voltage, fuel system pressure and PWM operation on fuel injection quantities of a H.P. fuel injector are measured. Also, the measured data of the H.P. fuel injector fed by the injector driving circuit are defined as the fuel injection curves. Finally experimental results are provided for verification of the proposed injector drive circuit.