Modeling and Identification of a Gasoline Common Rail Injection System

The precision of direct fuel injection systems of combustion engines is crucial for the further reduction of emissions and fuel consumption. It is influenced by the dynamic behavior of the fuel system, in particular the injection valves and the common rail pressure. As model based control strategies for the fuel system could substantially improve the dynamic behavior, an accurate model of the common rail injection system for gasoline engines - consisting of the main components high-pressure pump, common rail and injection valves - that could be used for control design is highly desirable. Approaches for developing such a model are presented in this paper. For each key component, two models are derived, which differ in temporal resolution and number of degrees of freedom.

Experimental data is used to validate and compare the models. The data was generated on a test bench specifically designed and built for this purpose. The test bench consists of the relevant components of a current production four-cylinder gasoline engine which were slightly modified in order to mount sensors. The detailed setup of the test bench is also described in this paper. Validation measurements show that the proposed model provides a good approximation of the real fuel injection system.