Research And Development On Fault Diagnosis System Of Marine Diesel Engine

Diesel engine as the ship main power plant operation in harsh environmentalconditions, its running state not only directly affects the combat effectiveness of the ship,but also affects the personal security, task completion and huge economic benefits.Therefore, the diesel engine effectively condition monitoring and fault diagnosis technologyresearch is of great significance.This paper takes the16VPA6V-STC diesel engine as the research object, according tothe design concept of fault diagnosis expert system, combining with the application ofdatabase SQL Server2008software and interface programming tools VB2008, developingpractical diesel engine fault diagnosis expert system, realizing the real-time conditionmonitoring and trend prediction of diesel engine.The main work is as follows:1) Through analyzing the main failure forms of16VPA6diesel engine, and accordingto user’s requirements, proposing the each function module and interface design of faultdiagnosis expert system.2) Researching the knowledge database, inference mechanism and explain mechanismof expert system, determining the ways of knowledge acquisition, representation, interfaceinterpretation method, establishing the knowledge database of expert system, includingmonitoring parameters, facts, rules, countermeasures library and so on, and also establishingthe corresponding data table in the SQL database, and establishing the correspondinginterface interpretation mechanism at the same time.3) According to the thermodynamic parameters fault diagnosis technology, comparingthe diesel engine performance parameters with its threshold, establishing the real-timemonitoring and alarm module of diesel fuel system, lubricating system, cooling system,charging system and so on. Analyzing the corresponding relationships between the mainperformance parameters and the failure mode, according to the corresponding faultdiagnosis inference rules, establishing the fault diagnosis module based on thermodynamicparameters.4) For the cylinder head vibration signals collected by the sensors, synthetically usingthe theory of vibration signal analysis technique, through LABVIEW pretreatment,extracting the characteristic parameter of waveform, frequency spectrum, cepstrum andpower spectrum, establishing the fault diagnosis module based on vibration signal analysis. Through the analysis found that the diagnosis based on vibration signals of cylinder headcan effectively diagnose cylinder liner wear, valve leakage and so on.5) In order to better forecast the trend of diesel engine running state, this paper putforward the concept of health degree of diesel engine. Using the theory of analytic hierarchyprocess to establish diesel engine health assessment system，determining each evaluationcontents and its weight coefficients which affect the health state of diesel engine, weightedanalyzing to calculate the health degree of diesel engine system, and taking the time as theabscissa, mapping health trends.