尿素箱水加热电磁阀失效模式及监测方法的研究

随着国家对环境污染问题的日益重视,对于汽车尾气排放的要求也越来越严格。目前,国内消除尾气中的NOX(氮氧化物)主要技术路线是通过SCR(选择性催化还原)技术,利用尿素的还原性将NOX还原成N2。针对尿素低温结晶特性,尿素箱水加热电磁阀控制发动机冷却水对尿素箱进行加热,其失效会使尿素溶液过加热,导致尿素溶液性能下降,从而发生SCR转换效率过低问题。本文主要从尿素箱水加热电磁阀工作原理、控制逻辑出发,研究市场常见的失效模式,并提出一种监测方法,便于高效的判断故障点,避免引起后处理故障。

With the increasing attention of the country to the problem of environmental pollution,the requirements for automobile exhaust emissions are more and more strict.At present,the main technical route to eliminate NOX(nitrogen oxide)in exhaust gas in the domestic is to reduce NOX to N2 through SCR(selective catalytic reduction)technology,using the reducibility of urea.According to the characteristics of low temperature crystallization of urea,the cooling water of the engine is heated by the solenoid valve of the water heating in the urea tank.The failure of the valve will make the urea solution overheated,which leads to the deterioration of the performance of the urea solution and the low SCR conversion efficiency.Based on the working principle and control logic of the water heating solenoid valve in the urea tank,this paper studies the common failure modes in the market,and puts forward a monitoring method,which is convenient to judge the fault points efficiently and avoid causing post-processing faults.