Influence of injection parameters on pressure fluctuation amplitude inside the oil pipe of common rail system

Oil pressure fluctuation caused by last injection may lead to oil volume deviation during multi-injection of high pressure common-rail system. This paper conducted an experimental research on the relationships between pressure fluctuation amplitude and injection parameters including rail pressure and injection pulse width. Results show that the change of pressure fluctuation amplitude is not monotonic with the increase of either rail pressure or injection pulse width. One-dimensional pipe model taking into account of oil viscosity was built using the CFD method where inlet and outlet boundary conditions of the model use constant pressure and orifice respectively. The model was calculated by MacCormack+TVD finite difference method and the results well demonstrate the influencing mechanism of injector closing time on pressure fluctuation amplitude. The oil pressure fluctuation amplitude inside the pipe connecting common rail with injector changes periodically with the increase of injection pulse width, but it increases with the increase of rail pressure as a whole and oscillation occurs locally. The period of oscillation increases with the increase of rail pressure.