Minimizing Gasoline Direct Injection (GDi) Fuel System Pressure Pulsations by Robust Fuel Rail Design 2011-01-1225

Gasoline direct injection (GDi) engines have become popular due to their inherent potential for reduction of exhaust emissions and fuel consumption to meet increasingly stringent environmental standards. These engines require high-pressure fuel injection in order to improve the fuel atomization process and accelerate mixture preparation. To achieve a lower-cost system, a single-piston high-pressure fuel pump design is often employed due to its relative simplicity. However, pumps of this design are acknowledged as the source of high levels of fuel pressure fluctuations which can lead to audible noise, variations in the amount and spray quality of fuel delivery from cylinder to cylinder, compromised durability and consumer dissatisfaction.

In this paper, the design process for a high-pressure fuel rail assembly using Robust Engineering methodology is presented. Using quasi-one-dimensional simulation, three control factors are studied in determining the optimal design for an in-line 3-cylinder engine fuel rail assembly which produces the lowest feasible levels of fuel pressure pulsations while maintaining robustness to various noise factors such as uncontrollable design parameters and operating requirements. Noise factors which were studied include fuel type and temperature, engine rpm, and fuel injection parameters.