Optimized Soot Monitoring by Ammonia Injection in a sDPF System for BS6.2 Application

The BS6 norms (phase 1) were implemented in India from April 1, 2020 and replaced the previous BS4 norms. Phase 2 of the BS6 norms, which came into effect on April 1, 2023. In accordance with the regulation requirement, effective performance of after treatment systems like DPF and SCR demands critical hardware implementation and robust monitoring strategies in the extended operating zone. Effective OBD monitoring of DPF, which is common to all BSVI certified vehicles, such that the defined strategy detects the presence or absence of the component is imperative. A robust monitoring strategy is developed to detect the presence of the DPF in the real world incorporating the worst possible driving conditions including idling, and irrespective of other environmental factors subject to a location or terrain. The differential pressure sensor across the DPF is used to study the actual pressure drop across the DPF. Additional for BS 6 (phase 2) PM sensor becomes an important part to keep the soot under monitoring. PM sensor is a costly affair, and it impacts the overall cost of the system.

This paper briefs about the PM sensor removal in a sDPF system. The soot monitoring will be enabled by extra ammonia injection and detecting the NH3 slip. The performance parameters, methodology derived for evaluation of key parameters and validation of the calibration in chassis dynamometer, on road at various altitude and temperature zones with empty and loaded DPF sample which serves to overcome the challenges in OBD monitoring with respect to DPF. Validation results assure zero misdetections in the field to avoid inconvenience to the customer. By using this approach, we could do soot monitoring of sDPF with existing architecture without adding PM sensor which will save rupees of 3,000 per vehicle. This strategy detects robustly a normal sDPF as good part and detects robustly a defect sample as defect sample. We could see clear gap between WPA sample and BPU sample which shows the robustness of the strategy followed for soot monitoring of sDPF. This strategy has potential to reach higher IUPR ratio with 95% detection accuracy and without any misdetection.