Research Of OBD Control Strategy And Calibration Optimization On Common Rail Diesel Engine

According to the requirements of HJ437-2008 regulation, heavy/medium-duty truck in CHINA IV phase must be installed the OBD system, engine and vehicle emissions related components in real-time monitoring and diagnosis by OBD system. A good OBD control strategy is the important prerequisite to judge whether the OBD system is mature and reliable. The mature control strategy can monitoring the emissions system more accurate, adapt to more complex environment and realize higher OBD calibration efficiency and quality. To carry out the research work of OBD control strategy has the significant academic value and application prospect.In this paper, the author has carried on the detailed research on the OBD control strategy of BOSCH EDC17 SW platform, including the logical architecture of diagnosis module, the sensors, actuators work principle and diagnosis strategy analysis, mainly studies the after-treatment of SCR NOx control limit monitoring strategy and the fault indicator, fault code and torque limiter calibration strategies, the author has carried out the OBD calibration work in the engine test bench and hardware in the loop (HIL) simulation system on the C A4DK-22E4 engine, make the engine meets the OBD2+NOx control regulations, smoothly to get the announcement and pass the witness test.Summed up the research work:1. Research the overall architecture and logical strategy of diagnosis module in EDC17 platform software. Detailed analysis the diagnosis strategy of the temperature sensor, pressure sensor, accelerator pedal sensor, speed sensor, NOx sensor and fuel injector, urea pump actuator, has studied common failure of the sensors, actuators, and system reaction during sensor failure, also the reasonable OBD calibration process were summarized. Implement more effective NOx conversion efficiency monitoring by subdivided work point according to engine exhaust temperature and quantity. Research on treatment mechanism to avoid long-term error faults active during engine/vehicle factory end-of-line session.2. Designed OBD calibration workflow based on EDC 17 platform, had done the sensors and actuators diagnostic calibration combining CA4DK-22E4 engine in the actual engine test bench and the HIL system, optimized the calibration of NOx conversion efficiency monitoring. Finally completed the higher quality of OBD calibration work.