The Research Of Fault Diagnosis Strategy For Diesel Particulate Filter Of Heavy Duty Diesel Engine

Compared with gasoline vehicles,because of the outstanding advantages in power and economy,diesel vehicles have been more widely used in Heavy duty locomotive field.With the development of the emission law,Diesel Particulate Filter(DPF)will be an indispensable component in after-treatment system.The national regulations HJ437 stipulate explicitly that vehicles meeting the requirements of China IV must be equipped with OBD systems.In our country,the OBD system research of DPF started late,The technology is incomplete,relied on the mature technology of foreign.So it is necessary to analyze the fault diagnosis strategy of DPF.In the first part,the paper summarizes the disadvantages of the research about fault diagnosis of DPF based on the current study at home and broad.Refer to the emission regulations and national standards,the functional requirement,Emission requirements and communication requirements of the diagnostic system are analyzed.And on the basis of that,the OBD system and the united simulation system are designed.Then,the mathematical model of working process are established based on the working mechanism of DPF,including the pressure drop model,the soot load model based on flow resistance,the soot load model based on simulation,the regeneration model.The models are the basis for diagnosis.In the third part,the paper analyze the influence to engine operation of the fault,formulate the fault diagnosis strategy and diagnosis logic based on the fault characteristics of DPF.The fault code is defined according to the SAE 2012 standard.Based on regulatory requirement,the fault manage strategy are formulated,including the control of fault code,MIL fault indicator and torque limiter.In the last part,DPF diagnostic module is developed on Matlab/Simulink simulation platform.This paper put forward an united simulation system as the development,debugging and validation system.The system including DPF control system and diagnostic module based on Matlab/Simulink and stateflow,DOC+DPF after-treatment system based on AMEsim,Diagnosis interface based on Labview.The diagnostic module is debugged and verified based on united simulation system.