《三元催化转化器应用与检测》-毕业论文（设计）.doc

PAGE 摘 要 社会发展，汽车保有量迅速增加，随之而来汽车尾气造成的环境污染问题也日趋严重。三元催化转化技术是目前应用最广泛，效果也最显著的发动机尾气机外净化技术。三元催化转化器可以使发动机尾气中的有害排放物如CO、HC、NOx同时降低90%以上，使汽车尾气污染得到有效控制。 许多车辆在实际使用过程中，由于使用不当造成三元催化转化器早期失效、损坏，致使它失去了减排的作用并造成发动机故障。本文分析三元催化转化器的结构、性能的特点，研究车辆使用特性对三元催化转化器性能的影响。研究表明,要使三元催化转化器正常使用,应使用规定级别或以上的润滑油、高品质的无铅汽油，保持发动机机械方面良好的工作状态，发动机电控系统也必须正常，还有车辆不宜长时间怠速等。 在使用特性研究的基础上,分析了三元催化转化器的故障形式,研究了不同故障的检测方法。三元催化转化器的故障可分为三类，机械损伤、堵塞和转化性能变差或失效。机械损伤可以通过简单的人工观察来检查。三元催化转化器堵塞的测试方法有真空测量法、排气背压检测法和进气管碳氢化合物浓度测量法等。对于三元催化转化器转化性能变差或失效的检测则有转化器出入口温差法、双氧传感器信号电压波形分析法和怠速试验法与快怠速试验法相结合等手段。 关键词：三元催化转化器，结构性能，使用，检测 Three-Way Catalytic Converter Application and Testing ABSTRACT Living standards development makes life better and better. More and more people tend to have their own vehicles to meet transportation needs in daily life, which also brings up a deteriorating environmental pollution problem. 3-way catalytic converter is the most popular and efficient engine emission clean-up technology.3-way catalytic converter can reduce harmful CO, HC and NOx emissions by more than 90%, thus effectively curb the pollution brought up by emissions. Many 3-way catalytic converters in vehicles may suffer an early failure and get broken due to improper use, and thus lose the function of emission reduction and cause engine damage. We must be careful about the following items in the daily use of the vehicle, primarily using qualified or high-graded lubricants and lead-free gasoline in engine, keeping engine working in a sound status both mechanically and electronically, and avoid long-time idling speed. Failure to understand and attach enough importance on 3-way catalytic converter in service work often leads to judgment error and getting half the result with twice the effort. So we must not ignore the 3-way catalytic converter during troubleshooting the engine. The malfunction can be categorized into 3 kinds, mechanical damage, obstruction and weakening or disabled converting ability. Mechanical damage can be inspected by simple obse