Fuel Pressure Modelling in a Common-Rail Direct Injection System
The fuel pressure is one of the central control variables of a modern commonrail
injection system. It influences the generation of nitrous oxide and particulate
matter emissions, the brake specific fuel consumption of the engine and the power
consumption of the fuel pump. Accurate control of the fuel pressure and reliable
diagnostics of the fuel system are therefore crucial components of the engine
management system. In order to develop for example control or diagnostics algorithms
and aid in the understanding of how hardware changes affect the system,
a simulation model of the system is desirable.
A Simulink model of the XPI (Xtra high Pressure Injection) system developed
by Scania and Cummins is developed. Unlike the previous models of the system
available, the new model is geared towards fast simulations by modelling only the
mean flow and pressure characteristics of the system, instead of the momentary
flow and pressure variations as the engine rotates. The model is built using a modular
approach where each module represents a physical component of the system.
The modules themselves are based to a large extent on the physical properties of
the components involved, making the model of the system adaptable to different
hardware configurations whilst also being easy to understand and modify.
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Last updated: 2019-08-05