The Car Catalytic Converter Fault Diagnosis Model

In recent years, with the progress of the society, the automobile in our country increases rapidly, and auto emission really becomes main pollution sources of urban air. In order to reduce emission, our country will implement the GBIII in July of this year, so the researching in auto emission control is very important in modern auto industry.It is one of the most effective ways to put three way catalyst on the vehicle. However the three way catalyst is apt to present the damage, poisoned, overheat wears out and normal wears out, etc in the auto goes, causes the efficiency of transforming to drop, and then makes the catalysis lose efficiency. So, the transformation efficiency of the catalysis should be monitored , the GBIII requires each one to dispatch from the car factory should have On-Board Diagnose(OBD) system, and the catalysis on board diagnosis is one of the most important departments of the OBD.When the assemble exhaust coming from the engine pass the catalyst, the air fuel ratio (AFR) changes because of catalysis. This paper on the basis of researching of catalysis principle and the thesis of engineers national and abroad choose the storage dominated model as diagnosis model, the model is simple and suitable for online real-time processing of data, etc. The model's parameter estimating is the key to guaranteeing the precision of models, so estimate the parameters of the model with AFR analysis and experimental data, based on estimating the oxygen storage level indirectly and recursive weighted least squares. Model simulation and experimental result show the structure of model is suitable and parameter identification is feasible, the storage dominated model has wide application prospects in the catalysis on-board diagnosis.