Nonlinear characteristics of fuel injection quantity for a high-pressure common rail fuel injector

Based on a validated AMESim simulation model of the high-pressure common rail injector, the nonlinear characteristics of the fuel injection quantity were investigated in this article. The nonlinear relationship between the fuel injection quantity and the fuel injection pulse width was described quantitatively through the definition of the fuel injection quantity nonlinearity (FIQN). D-optimal experimental design and partial least squares regression were employed to construct response surface models for the FIQN under varying rail pressures. Then the analysis of variance (ANOVA) was conducted based on these predictive models to determine the significance of all factors by evaluating whether their p-values were less than 0.05. Additionally, correlation analysis was performed to reveal the degree and trend of influence each factor has on the FIQN. The results indicate that, under identical working conditions, single-factor effects are more significant on the FIQN compared to the interaction factors. The interactions of parameters themselves contribute little to the FIQN. While some parameter interactions do influence the nonlinear characteristics of the fuel injection quantity, the leading interaction factors vary across different rail pressures. Specifically, at 60 MPa rail pressure, the correlation coefficient of the interaction between the inlet orifice diameter and outlet orifice diameter is 0.50, which is the only interaction factor strongly related to the FIQN. When the inlet orifice diameter is at a high level and the outlet orifice diameter is at a low level, the nonlinear relationship between the fuel injection quantity and injection pulse width can be significantly improved.