Research On Fault Diagnosis System Of Vehicular TWC

With the rapid economic development, China's commercial vehicles and the family car is in a sharp increase, However, urban air pollution problem has become increasingly prominent. In motor vehicle emission control technology,the three-way catalyst (TWC) is more effective purification technologies. TWC also reduced the influence of vehicle emission to atmosphere quality in cities. But lots of TWC in actual use were invalid before they got to the deadline, so it's significant to research the fault diagnosis system for TWC.By physical and chemical void mechanisms, a complete fault diagnosis system of TWC is established in this thesis. This system can detect and calculate the conversion efficiency of TWC which has chemical invalidation and the air flow characteristic in front and back of TWC which has physical invalidation. In this thesis, the practical tester is designed and strategy of fault diagnosis system for TWC is proposed.The fault diagnosis system of TWC contains hardware and software components in this study. The main function of hardware component is to obtain the signals of pressure sensor signal, oxygen sensor signal and the front and back emission components of catalytic converters. And the real-time transmission of data to computers. The main function of software component is to analysis the data from hardware,to extract failure feature vector of TWQand to diagnose the failure state of TWC.This thesis is focus on the study which includes the feasibility of the diagnosis system and the method of diagnosis for TWC. It is shown by many data and the testing result that the valid method of diagnosis for TWC has been found and the changing law of characteristic parameter is obtained. Meanwhile, it is also shown that it is feasible to judge the status of TWC by using the diagnosis parameter andthe purpose of study is gained. The system which was discussed made a foundation for consummating the TWC's diagnosis system and the further studying. The practical detecting system proposed here is innovative, practicable and economical, and it fits to service company and institution of vehicle detecting.