Calibration and Optimization of OBD Strategies for Selective Catalytic Reduction Systems for BSVI Application

The adoption of BSVI emission norms for Indian domestic market brought a very stringent window for pollutants. For CI engines, the major impact was in the reduction of NOx by 68% and PM by 82% from BSIV norms. Technologically advanced after treatment systems like SCR / DPF / LNT aid to meet the stringent emission norms. Implementation of high-end after treatment systems in vehicles, requires precise monitoring and fool proof feedback systems. On Board Diagnostics (OBD) makes this possible. OBD is used to monitor the performance of after treatment systems and warn the user in case of deterioration. The challenges in framing OBD strategy increases with more electronic hardware and complex algorithms taking control, to monitor precise information on system performance. For a fool proof OBD monitoring of the exhaust system, a complete understanding of the SCR system and its components in terms of hardware specifications and software functionality is critical. Correct OBD strategy ensures proper functioning of the SCR system to achieve the legislated emission limits for NOx and provide feedback on system performance. In this paper, the legislative requirements and implementation process of OBD strategy for various SCR components, SCR system performance and AdBlue quality for BSVI application is discussed. The SCR system On Board Diagnostics is calibrated and optimized to achieve a fool proof robust monitoring and feedback system. Methodology for calibration, monitoring and validation of the defined OBD strategy is explained with case studies.