MODELLING OF DYNAMIC RESPONSES OF AN AUTOMOTIVE FUEL RAIL SYSTEM, PART II: ENTIRE SYSTEM

The computer model developed for calculating pressure fluctuations inside an automotive fuel injector (Hu et al. Journal of Sound and Vibration (submitted)) is extended to the entire fuel rail system, which consists of six injectors, a pressure regulator, pressure damper, fuel pump, and torturous fuel supply and return lines. Since the pressure fluctuations generated inside any injector can propagate throughout the entire fuel rail system, the responses of all injectors are coupled. The presence of a pressure regulator may also affect the dynamic responses of the fuel rail system. In Part II of this paper, formulations for describing pressure fluctuations inside the injectors, pressure regulator, and fuel rails are derived and solved simultaneously. The effect of twists and turns of the fuel lines on the losses of fluid kinetic energy, and that of wave propagation throughout the fuel rail system are taken into account. The computer model thus developed is validated experimentally. Measurements are conducted on a test bench that simulates a real engine with injectors fired in a particular order. The calculated pressure fluctuations inside different injectors and fuel lines are compared with the measured data under various working conditions. Favorable agreements are obtained in all cases.