成都纺织高等专科学校机械工程学院
毕业论文
课题名称： 柴油机后处理系统常见故障分析与检修 班级 ： 层次：?本科 ?专科 学生学号：20130 指导老师： 杨 学生姓名：杨 学生专业：汽车检
成都纺织高等专科学校机械工程学院
2016年3月17日
成都纺织高等专科学校毕业论文 中文摘要
摘 要
随着改革开放以来我国经济飞速发展的同时环境也受到了相应的污染，为了我们子孙后代的的环境安全国家也不断进行政策管制。大气污染就是其中一种，污染的气体来自工业和汽车尾气，所以为了减少汽车有害气体排放国家制定了货车的国三 国四排放标准，相应的就有了货车后处理系统。
油机后处理柴系统的作用是对柴油发动机尾气的处理，该系统配的柴油车是国三和国
四系统的货车；而这个系统有两种方法分别对应国三的EGR+DPF（Exhaust Gas
Recirculation+ Diesel particle filter；废气再循环+柴油机颗粒捕捉器）与国四的SCR（Selective Catalytic Reduction 选择性催化还原）。
柴油发动机排出的尾气很多污染气体而后处理的系统就是用于对污染气体进行处理，处理的办法是将有害气体或污染气体进行转化为清洁气体，该系统的发明就是响应世界的减少大气污染号召；所以该系统的发明就是对大气的保护。
下面介绍一些后处理方法：1、SCR：selective catalytic reduction （ 选择性还原 ） 主要处理NO化合物。
2、DOC：Diesel oxidation catalyst （ 氧化催化器 ）主要用处理HC 、CO化合物。 3、 POC: Partial oxidation catalyst （ 部分颗粒氧化催化器）主要用来处理PM。 4、DOC：Diesel particle filter （柴油机颗粒捕捉器）主要用来处理PM。
5、EGR：exhaust gas recirculation( 废气再循环) 该技术将发动机废气引入进气管，降低进入气废气再循环该技术将发动机废气引入进气管，降低进入气从 缸的氧气浓度 ， 控制燃烧速度 ， 降低燃烧温度, 从而降低NO化合物的生成和排放。
以上就是后处理的一些方式，该篇论文会针对以上方法进行工作原理讲解，而对于该片论文的重点是尿素系统的讲解，其他只作为了解！
关键词： 选择性还原 氧化催化器 柴油机颗粒捕捉器 废气再循环 尿素系统
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成都纺织高等专科学校毕业论文 英文摘要
ABSTRACT
With the rapid development of economy in our country since the reform and opening to the outside environment is polluted by the corresponding at the same time, in order to our future generations of national environmental safety also ongoing policy regulation. Air pollution is one of them, from industrial and automobile exhaust gas pollution, so in order to reduce automobile harmful gas emissions country made the three countries of truck four emissions standards, the corresponding have truck post-processing system.
Oil machine processing wood processing system is used on diesel engine exhaust, forward of the truck diesel is four countries sanhe system; And this system has two kinds of methods corresponding to the three EGR + DPF (Exhaust Gas Recirculation + Diesel particle filter; Exhaust Gas Recirculation + Diesel particulate trap) and the four SCR (Selective Catalytic Reduction of Selective Catalytic Reduction).
Here are some post-processing methods: 1, SCR, selectivecatalytic reduction (reduction) Main processing NO compounds.
2, DOC: Diesel oxidation catalyst (oxidation catalysts) mainly use the HC, CO compounds. 3, POC: Partial oxidation catalyst (Partial oxidation catalysts particles) is mainly used to deal with PM.
4, DOC, Diesel particle filter (Diesel particulate trap) is mainly used to deal with PM. 5, EGR, exhaust gas recirculation (exhaust gas recirculation) the technology to the introduction of the engine exhaust gas inlet pipe, decrease in the gas exhaust gas recirculation the technique, introduces the engine exhaust gas inlet pipe, reducing oxygen concentration in the gas from the cylinder, control the burning speed, the lower combustion temperature, thus reducing the generation of NO compounds and emissions.
Is the way of the post processing of the above, the paper will be in view of the above methods are working principle, and for the interpretation of the thesis focuses on the urea system, just as other understand!
Keywords: selective reduction oxidation catalysts diesel particulate trap Exhaust gas recirculation system of urea
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成都纺织高等专科学校毕业论文 目录
目录
1 目录 .................................................................................................................................... 1
1.1柴油车尾气有哪些有害气体 ............................................................................................ 1
第一章 后处理系统工作原理 ............................................................................. 3
1.1 DOC后处理器工作原理 ............................................................................................... 3 1.2 POC原理 ....................................................................................................................... 3 1.3 DPF后处理器工作原理 ................................................................................................... 4 1.4 EGR工作原理 ................................................................................................................... 6
第二章 SCR工作原理 .................................................................................................. 7
2.1 两种技术路线的实现原理 ............................................................................................... 8 2.2 SCR组成 .................................................................................................................... 8 2.2.1尿素控制单元 ............................................................................................................ 9 2.2.2尿素泵 ................................................................................................................... 10 2.2.3尿素喷嘴 .................................................................................................................. 17 2.2.4催化消声器 ............................................................................................................ 18 2.2.5 添蓝罐 ................................................................................................................... 19 2.2.6 NOX传感器 ........................................................................................................... 21 2.2.7 催化器前后温度传感器 ........................................................................................ 26 2.2.8 加热电磁阀 ............................................................................................................. 27 2.2.9 尿素管 .................................................................................................................. 27 2.2.10 尿素箱加热管路 ................................................................................................. 28
第三章 后处理常见故障检测与维修 ................................................................... 29
3.1电控发动机国四整车电子网络架构 ............................................................................... 29 3.2后处理单元电气原理介绍 ............................................................................................ 29 3.3尿素压力建立失败 ....................................................................................................... 31 3.4 尿素消耗少 .................................................................................................................. 33
成都纺织高等专科学校毕业论文 目录
3.5 OBD 扭矩限制与不可清除代码 ............................................................................. 34 3.6 OBD灯亮 ..................................................................................................................... 43 3.7 尿素加热不放行 .......................................................................................................... 43 3.8 NOX转化效率低 ......................................................................................................... 45 3.9闻到一股氨气味 ................................................................................................................ 46 3.10 尿素结晶 .................................................................................................................... 47
第四章 后处理部分零件检测及故障排除 ...................................................... 48
4.1 DCU及尿素泵总成 ...................................................................................................... 48 4.2 尿素泵接口定义及检测方法 ....................................................................................... 49 4.3 尿素喷嘴 ...................................................................................................................... 52 4.4 排气温度传感器 （前排温） ..................................................................................... 53 4.5 氮氧传感器 .................................................................................................................. 54 4.6 尿素液位及温度传感器 ............................................................................................... 55 4.7 大气温度传感器 .......................................................................................................... 56
第五章 故障诊断维修 .................................................................................................... 58
5.1 诊断过滤器 ....................................................................................................................... 58 5.2 诊断尿素喷嘴 ............................................................................................................... 59 5.3 诊断尿素泵 .............................................................................................................. 60 5.4 诊断 T形接头 ......................................................................................................... 61 5.5 诊断尿素压力传感器 .................................................................................................. 62 5.6 诊断排气温度传感器 .................................................................................................. 63 5.7诊断氮氧传感器 ............................................................................................................ 64 5.8 诊断外部尿素管路 ...................................................................................................... 64 5.9 诊断内部尿素管 .......................................................................................................... 65 5.10 诊断加热电磁阀 ........................................................................................................ 67 5.11 诊断尿素泵总成 ......................................................................................................... 68 5.12 诊断 DCU .............................................................................................................. 68 5.13 CAN通讯问题 ........................................................................................................... 68 5.14 诊断尿素箱总成 ........................................................................................................ 69