The regeneration process of a Diesel Particulate Filter (DPF) consists of an increase in the engine exhaust gas temperature by using post injections and/or exhaust fuel injection during a period of time in order to burn previously trapped soot. The DPF regeneration is usually performed during a real drive cycle, with continuously changing driving conditions. The quantity of post injection/exhaust fuel to use for regeneration is calculated using a combination of an open loop term based on engine speed, load and exhaust gas flow and a closed loop term based on an exhaust gas temperature target and the feedback from a number of sensors. Due to the nature of the system and the slow response of the closed loop term for correcting large deviations, the authority of the fuel calculation is strongly biased to the open loop. However, the open loop fuel calculation might not be accurate enough to provide adequate temperature tracking due to several disturbances in the system.
This paper discusses a novel methodology for temperature control of the DPF during regeneration. A correction factor, which is a function of fuel computed by open loop and closed loop methods, is defined. This factor is used to generate an adaptive fuel correction map which updates during every regeneration event. At the end of the drive cycle, the map is stored within the Non Volatile Memory of the engine control unit, for use in the next regeneration cycle.
The strategy is validated using rapid prototyping tools. This control strategy results in improved temperature control during regeneration of the DPF which will increase the average quality of the regeneration events.