Fuel Rail Pressure Control Characteristics of a GDI High-Pressure Fuel Pump Using a Newly Developed Experimental System Controlled with a Microcontroller

Abstract

An experimental system was developed to evaluate the fuel injection parts of a gasoline direct injection engine. An AC motor and an inverter were used to rotate the camshaft in the engine cylinder head. A single plunger high-pressure fuel pump (HPFP) driven by a square cam at the end of the camshaft was used in the gasoline direct injection engine. The rotation position of the square cam was measured by a rotary encoder. The developed system allows control of the camshaft rotation speed, the HPFP pressure control valve (PCV) opening and closing timing, and the fuel injection duration, which are three important factors affecting the fuel rail pressure (FRP). It is confirmed that the fuel rail pressure can be made to vary wit different combinations of these three factors. By using the experimental system developed in this study, the fuel rail pressure can be effectively controlled in the range of 3 MPa to 20 MPa. The most influential factor for control of the fuel rail pressure was the HPFP PCV opening and closing timings. With the proposed using the experimental system, the rail pressure, fuel rail pressure wave characteristics, and the injector drive characteristics can all be assessed under various fuel injection conditions.