Study On The Identification Of Diesel Engine Valve Clearance Change Based On Vibration Characteristics

The working conditions of diesel valves and valve base are abominable.The valve collided with the valve base when the valve switch.The abrasion lead to valve clearance change.lt makes ventilation efficiency fall down,the diesel engine power,Service life and reliability reduction.Therefore,it is necessary to identify the abnormal change of the valve clearance of diesel engine at the early stage and eliminate the hidden trouble.This article takes valve clearance change of marine medium-sized diesel engine WD615 as the research object,secondary image analysis,pattern recognition technology as the basis for further research of diesel machine signal fault feature extraction recognition method.There are so many excitation source of vibration in diesel engine running process,and its frequency range is wide,various excitation source after transmission and coupling accordingly,make the surface vibration signal contains very complicated composition and contains rich state information.The characteristic parameters of vibration signals that can quantitatively depict vibration characteristics can be extracted effectively,and the working condition of diesel engines can be monitored without affecting the normal operation of diesel engines.In this paper,the local wave and independent component analysis method is applied to separate the impact response of the valve seat from the surface vibration response of the measured diesel engine to obtain a single excitation source response,combining the analysis of mechanism of diesel valve clearance anomalies,the internal relationship between the valve clearance and valve seating impact vibration characteristics is revealed,the diagnosis method of diesel engine valve clearance change is established,and a quantitative expression of clearance of diesel engine valve is constructed,The vibration characteristics of the cylinder head under different working conditions and the characteristic parameters and are discussed,time-frequency Spectrum of vibration signal from cylinder head of WD615 diesel engine received by continuous wavelet transform,Experiment shows that the characteristic parameters under clearance change working condition of diesel engine valve presents obvious difference,and the vibration signals of of diesel engine valve clearance change can be quantitatively represented by the above characteristics.The vibration signal is a typical non-stationary signal,and the direct link between the fault is difficult to determine.This article make use of probabilistic reasoning,fuzzy reasoning and other uncertainty theory to processing and analysis based on the probability density function.According to the principle of minimization of information entropy,the feature data is first subjected to multi-zone discretization processing Then,the relation between the eigenvalues is mapped to the difference between SPODE and the assumption of independence in traditional naive Bayes method.After Weigh the super 1-dependent classifier by the difference,The accuracy of identifying the clearance condition of the valve is improved by the new method based on the characteristic parameters of vibration response.