Research And Development Of Electronic Control EGR System Of Diesel Engine

Exhaust gas re-circulation (EGR), which is considered to be the most feasible and most effective method to reduce NOx emission, has been widely studied and successfully applied in production. Acceptable EGR rate control is the key technology in EGR, which is closely related to not only diesel engine system itself but also the EGR control system. In this study, the method of one-dimensional computer simulation is used to simulate working process of diesel engine EGR system, and based on the simulation results EGR electronic control system has been developed and EGR valve regulated by stepping motor has been designed.In this paper, a simulation model has been proven based on Turbocharged, Intercooled Vehicle Diesel Engine using AVL-Boost and calibrated using bench test results. After that, a new simulation model with EGR system has been designed and then the optimization of construction parameters has been done. The simulation studies under variable speed and load conditions were received and the simulation results provided a basis on studies of the influences of EGR rate on the combustion and emission characteristics of diesel engine.According to the working principle of EGR system the EGR electronic control system was designed in this paper including both hardware and software. In addition, the calibration software was developed. The hardware of the ECU used C8051F340 as CPU, collected the engine speed signal/load signal/water temperature signal to inquire the EGR control MAP to calculate the controlling amount. Finally the expected control of EGR rate is achieved. With the idea of modularization design method the software was designed with C language. The calibration software was developed to implement communication control, condition monitor, parameters modify and store and condition curve performance. Finally this paper made the simulation experiment and the results shows that the ECU can meet the requirements of the EGR control system.After one-dimensional simulation, this paper designed the EGR value driven by stepping motor and carried out optimization on value body using one-dimensional/three-dimensional coupling computational method. The boundary condition of inlet and outlet that three-dimensional simulation for value body needed can be got from one-dimensional results. We can use them to analyze the flow field of the EGR value. Finally, EGR value flow characteristic was studied by experiment and the results of experiment showed that the value meets the requirements of design. The comparison between the simulated result and the experiment result also proved the feasibility of the CFD simulation.