Fuel-assisted in-cylinder oxygen fraction transient trajectory shaping control for diesel engine combustion mode switching

This paper presents a method for shaping the transient trajectory of in-cylinder oxygen fraction at intake valve closing (IVC) when combustion mode is switched from one to another in Diesel engines. To achieve this purpose, based on a non-equilibrium transient trajectory shaping (NETTS) control method, the fuel injection amount was adjusted within a given range (accommodated by adjusting fuel injection timing accordingly). Through air-path and fuel-path cooperative control, the transient trajectory of in-cylinder oxygen fraction can be bounded by a series of shaped-boundaries during tracking error converging. The dwell time between two consecutive combustion mode switching events can be effectively reduced. To evaluate the control algorithm, co-simulations were conducted using a GT-Power (a high-fidelity industry standard 1-D computational engine model software package) engine model and Matlab/SIMULINK.