Research on Correction of Flow Characteristics in Ballistic Zone of GDI Engine Injector

High-pressure injectors are the key actuators of a GDI engine. However, manufacturing deviation leads to the inconsistency of flow characteristics in the ballistic zone, which affects the accuracy of fuel control. Based on the feedback signal of driving voltage of high-pressure injector, the algorithm of recognizing the opening and closing action characteristics of needle valve is studied, and the self-learning method of flow characteristics and the compensation method of injection driving pulse width are proposed. The test results show that the method can effectively improve the consistency of flow characteristics in the ballistic zone for different fuel injectors, reduce the deviation from 25% to 10%, and effectively improve the fuel injection accuracy, so that fuel rail pressure can be increased, injection splitting can be adopted or injection splitting times can be increased under more engine conditions, so as to improve emissions.