Calibration and optimization of the electronic control of a SCR after-treatment system for a Common Rail Off-Road Diesel engine

Over the past decade Off-Road emissions legislation framework becomes more stringent. For this reason, OEMs decided to radically change their internal combustion engines, by adopting new technologies able to reduce pollutant emissions. The core of the work is focused on the description of the Closed Loop electronic control of a SCR (Selective Catalytic Reduction) system based on NH3 storage model and its calibration procedure. NH3 storage tests have been carried out on a real test bench with the aim of characterizing the SCR storage capacity as a function of Space Velocity and SCR inlet temperature. SynGas tests results have been taken as a reference. To better control the SCR ageing also injection adaption and NH3 slip detection strategies have been calibrated in the ECU. Finally, results have been validated over homologation cycles and on worst-case maneuvers, refining the calibration when needed. At the end of the activity, the engine was ready to be homologated, being compliant with the EU Stage V requirements.