Research On Key Technologies Of Fault Diagnosis For High Pressure Common Rail Diesel Engine

With the development of electronic control engine,the increasing complexity of electronic devices,the increasing application of software and mechatronics,the risk of systematic failure and random hardware failure gradually increases.As for the input components of engine system,the emission regulation National VI requires that the OBD system shall at least monitor circuit failure and rationality failure.At the same time,in terms of functional safety,the automotive electronics industry standard Iso26262 requires to avoid unreasonable risks caused by automobile electronic system failures.At present,the research and development of the fault diagnosis system of high pressure common rail engine is not very mature.Therefore,it is urgent to develop a fault diagnosis system to adapt to emission regulations and systems.This paper analyzes the development and research hotspot of fault diagnosis system and key component diagnosis methods of high-pressure common rail diesel engine at home and abroad,and studies the working principle and fault mechanism of different components in detail,so as to select different monitoring strategies for different components combined with their functional requirements.After the monitoring module reports the fault information,the fault management module selects the buffeting method according to the diagnosis requirements.After the completion of the buffeting,the fault inspection module sets the fault status to enter the fault priority scheduling module,processes the fault according to the priority order,sends out the suppression function,and stores the fault event.Based on this architecture,the fault diagnosis system strategy is built with MATLAB \ Simulink as the modeling tool.For the coolant temperature sensor,accelerator pedal position sensor,rail pressure sensor,crankshaft position sensor,fuel metering unit,battery voltage,ADC module and other components,the over limit detection strategy model and partial rationality detection model are built;for the no signal fault and error signal fault of crankshaft position sensor,the fusion diagnosis strategy of model diagnosis and logic diagnosis is adopted It can identify the fault accurately and quickly when there is no fault input interference.In the process of rail pressure control,two strategies,rail pressure sensor and fuel metering unit,are adopted to monitor rail pressure gradient and regulator respectively,and the monitoring model is built and simulated.For misfire fault,AMESim software is used to simulate the fault and collect data,so as to extract fault features for fault diagnosis,and simulation verification is carried out.The verification results show that the fault can be accurately identified.Connect the established fault diagnosis strategy model with the overall engine control strategy,download the generated code to the target ECU,select some sensors diagnosis strategy for offline simulation,and verify the diagnosis procedure by simulating the fault.The simulation and test results verify the correctness and feasibility of the fault diagnosis system built in this paper,which indicates that the fault diagnosis system can effectively realize the fault diagnosis of diesel engine.