SCR urea metering system design and control strategy

Currently, energy-saving cars of the subject as a universal worldwide attention for the people, in order to reduce vehicle emissions of harmful gases endanger the environment, countries in the world have adopted a more stringent emission regulations.To meet the imminent implementation of the State Ⅳ standard, domestic R & D solutions. In this paper, catalytic reduction system (SCR) of the operating mechanism, through a combination of experimental and theoretical research methods, post-processing platform built SCR, based on independent innovation in the design of SCR's core components: exhaust after treatment urea solution and air mixture metering pump systems, is currently in performance testing and calibration phase. In addition, the author's major work done: 1. In the SCR on the basis of the platform, the control strategy and car auto diagnostic system (OBD) diagnostic strategy simulation designed to verify the rationality and effectiveness of the strategy. 2. The subject of using CAN bus for data communication and control, in order to make the engine electronic control unit (ECU), urea injection control unit (DCU), GROUDFUS urea metering pumps and other VDO NOx-Sensor data bus node effective interaction validation control node strategy is effective. J1939 CAN communication protocol for communication protocols and communication theory and computer simulation software in CANoe J1939 protocol development of in-depth study and research, in the simulation environment to create a consistent communication protocol J1939 virtual network, and complete use of the virtual network node of the actual testing, to achieve a practical hardware and virtual nodes and virtual instrument DCU communication nodes, communication test results are satisfactory, the development of communication module to meet the requirements of real-time communication. Shorten the development cycle and reduce development costs. 3. And the other members of Task Force set up a bench test system SCR, and conducted a preliminary test data analysis and calibration, test results show that the subject of solutions to meet the national stage Ⅳ emission regulations. 

Keywords: SCR, OBD, CAN bus, J1939 protocol, CANoe