柴油机Urea-SCR控制系统设计与试验  

Design and Test of Urea-SCR Control System for Diesel Engine

作　　者：胡杰[1,2] 王立辉[1,2] 王天田[1,2] 

机构地区：[1]武汉理工大学现代汽车零部件技术湖北省重点实验室,武汉430070 [2]武汉理工大学汽车零部件技术湖北省协同创新中心,武汉430070

出　　处：《农业机械学报》2016年第2期349-356,共8页Transactions of the Chinese Society for Agricultural Machinery

基　　金：国家自然科学基金项目(51406140);国际合作项目(2012DFA11180)

摘　　要：SCR后处理技术是目前降低柴油机NOx排放量的主流技术,首先基于自主开发的SCR控制系统,阐述了系统的组成、工作及反应原理。其次通过协调控制策略以确保系统内部各模块运转正常,通过原机排放模型和化学反应动力学模型作为前馈控制得到尿素基本供给量,通过排温修正模型进行瞬态排温修正,利用发动机排温和储氨量的对应关系对氨泄漏进行有效控制,根据OBD法规要求当发动机NOx排放量超标时进行报错。最后对系统中的各类传感器、执行器特性及原机排放MAP、目标转化效率MAP进行了标定。系统与某型号发动机匹配良好,经ESC循环测试NOx比排放量为1.52 g/(k W·h),ETC循环测试NOx比排放量为2.09 g/(k W·h),控制系统能够有效地降低NOx排放量,满足国Ⅳ排放法规。SCR after-treatment is the mainstream technology to reduce the NOxemission amount. The self-developed SCR system ＇s composition,operating and reactor mechanism were presented,and the coordinate control strategy was used to assure that the system＇s inner module was operated regularly,the original emission model and chemical reaction kinetics model were adopted to obtain the raw value of urea supply amount,the exhaust temperature correction model was introduced to fix the instantaneous emission temperature,the relation between exhaust temperature and amount of NH3 storage was used to effectively control the NH3 leak amount,and failure warning was made according to the OBD regulation when NOx emission exceeded the standard. Each operation point had a NH3 coverage ratio threshold which can ensure NH3 leakage volume ratio was less than 1. 0 × 10- 5during the rapid heating process and try to improve the NOxconversion efficiency. According to the research results of the NH3 coverage ratio and storage,the estimation model was established,and the leakage control strategy was put forward. The sensors and actuators of the system,original machine emission MAP and target conversion rate MAP were calibrated. The dosing control unit using above control strategy was adopted in the target engine. Test results showed that the brake specific emissions of NOxin ESC and ETC were 1. 52 g /（ k W·h） and2. 09 g /（ k W·h）, respectively, which indicated that the self-developed SCR control system can effectively reduce the NOxemission amount and reach the national Ⅳ emission regulation.

关 键 词：重型柴油机 SCR系统 控制策略 标定 

分 类 号：TK421.5[动力工程及工程热物理—动力机械及工程]