基于模型的三元催化转化器故障诊断方法研究

Research on Model-Based Fault Diagnosis Method for Three-Way Catalytic Converter

催化器性能是车载诊断(on board diagnostics,OBD)系统必须监测的项目之一。根据催化器的储、放氧特性,分析催化器储、放氧的主要工作过程。根据双线性氧传感器信号,建立催化器的储、放氧模型,同时引入催化器的存储、释放氧气能力指数参数、催化器氧容量OSC、催化器存储、释放氧气速率μ等指标来对催化器性能进行评估。通过"浓稀法"试验,采用最小二乘法对模型的参数进行辨识。根据辨识结果,利用模型仿真对催化器性能参数进行估计,同时引入催化器老化因子ρ。研究结果表明:在催化器不同老化程度(ρ=1、0.8、0.6)下,催化器性能指标(、OSC、μ)均下降,能够有效反映催化器性能的变化,可用于催化器性能的在线估计。

Three-way catalyst performance is one of items which must be monitored by on-board diagnostics（OBD） system.Based on oxygen storage and release properties of three-way catalyst and analyzing its working process,a catalytic converter oxygen storage and release model was established on the basis of double linear oxygen sensor signals and a series of indexes,e.g.oxygen storage and release capacity index ,oxygen storage capacity OSC,oxygen storage and release rate μ etc.were introduced to evaluate catalytic converter performance.Based on the test of transition between ＂rich and lean＂ and adopting least square method to identify the model parameters,the performance parameters were estimated by using model simulation,and the catalytic converter aging factor ρ was introduced.Under different aging levels（ρ=1,0.8,0.6）,the catalyst performance indexes（、OSC and μ）decline,effectively reflecting the changes of converter performance,thus these indexes can be used for catalytic converter online estimation.