Emission constrained multiple-pulse fuel injection optimisation and control for fuel-efficient diesel engines

With the application of multiple-pulse fuel injec- tion profiles, the performance of diesel engines is enhanced in terms of low fuel consumption and low engine-out emission levels. However, the calibration effort increases due to a larger number of injection timing parameters. The difficulty of controlling the combustion phase also increases because of coupling between individual fuel injection pulses. In the pursuit of more efficient diesel engines, each fuel injection pulse needs to be optimised and actively controlled against component ageing, ambient condition changes and fuel variations. This paper presents an off-line method to compute the optimal multiple- pulse fuel injection profile with explicit considerations of both torque output and engine-out emission requirements. A multi- input multi-output feedback controller is designed to regulate the entire fuel injection profile against disturbances. Numerical simulation results are given based on a heavy-duty truck engine model.