基于AMESim的柴油机气助式SCR计量系统的仿真研究

Study on Simulation of Air-Assisted SCR Dosing System of Diesel Engine Based on AMESim

利用AMESim软件,建立了气助式SCR计量系统的模型,研究了喷射压力、进液管直径、进液管长度、喷射频率、占空比等参数对喷射压力波动和计量单元喷射量的影响。研究结果表明:喷射量与喷射压力、占空比成正比,与喷射频率成反比,进液管长度对其没有影响;进液管径小于4mm时喷射量迅速降低,大于4mm时喷射量变化不大;管长和占空比对喷射压力波动影响不大;喷射压力波动差值在进液管直径小于4mm时迅速减小,管径大于4mm时变化较为平缓;选择压差较小时的喷射频率作为计量单元的控制频率和采用变频控制可提高尿素喷射计量的精度。

A dosing model of air-assisted SCR system was developed based on AMESim to study influences of injection pressure, liquid inlet pipe diameter and length, injection frequency and duty ratio on injection pressure fluctuation and injection dose. Results show that, the injection dose is proportional to injection pressure and duty ratio,and inversely proportional to injection frequency. There is no influence of inlet pipe length on the injection dose. The injection dose reduces quickly when inlet pipe diameter is less than 4 mm and changes little when it. more than 4 mm. Inlet pipe length and duty ratio have little influence on injection pressure fluctuation. With inlet pipe diameter increase, injection pressure fluctuation magnitude diminishes quickly when inlet pipe diameter is less than 4 mm and changes gently when more than 4 mm. Injection precision of the dosing system can be improved if the injection frequency with rain. pressure difference and frequency conversion control mode are applied to the dosing system. These achievements are of significance for optimization of SCR dosing system design.