Design of the Electrical Drive for the High-Pressure GDI Injector in a 500cc Motorbike Engine

Abstract

In order to meet future emission regulations, improve the power and reduce fuel consumption of an engine, a high-pressure GDI injector is gradually replacing the conventional port fuel injector as it is able to provide fuel injection with a more effective fuel spray atomization and tip penetration. Engine performance can therefore, be improved by using such a high-pressure swirl injector. In order to fully utilize the advantages of the GDI injector, the electric driving circuit is required to be designed with a faster response and finer precision control. In this paper, a programmable injector driving circuit for various high-pressure GDI injectors is designed and presented. A Comparison between two driving strategies of GDI injectors is summarized. Experimental tests for the designed electric driving circuit are investigated to verify its feasibility. The test of the electric driving circuit for the injection quantity of the GDI injector is under the conditions of 10 MPa fuel pressures, 1200-2000μs injection pulse duration and DC 70V executing power voltage. The GDI injector coils are driven under three pulse width (12/5/3A) peak and holding current waveforms to generate the electromagnetic force to draw back and hold the nozzle needle of the injector. Also, PWM control is introduced to the 3A holding current during the last pulse duration for quickening the cut-off response time of the GDI injector. Results show that this electric driving circuit is capable of operating stably and assures the accurate injection quantity of the gasoline direct injector.