The Vibration Characteristic Analysis Of Engine Valves

As the power plant of vehicle, Engine’s running state directly affects the workingcondition of the vehicle. If we can determine vehicle’s current status, ascertain the fault causesand elimination methods timely and accurately under the condition of the engine withoutdisassembly, which will greatly improve the reliability and security of the vehicles use. Thefault associated with abnormal valve clearance in engine’s failure accounted for a largeproportion of all sorts of types, so it is of great significance to diagnose this type of fault.In this thesis, based on the analysis of engine’s valve clearance, we test the vibrationsignal in the condition of different clearance under different rotating speed, throughresearching the method of vibration signal’s analysis in detail, we combine the time-frequencyanalysis and wavelet multi-resolution analysis to analyze the signal and successfully build aset of practical vibration signal test system.Using this test system which is build in the thesis, we summarize the influence degree ofthe engine rotating speed and different clearance for the fault characteristic signal; meanwhile,use wavelet analysis to point out different kinds of valve failure accurately. Through theexperiment of testing DA462engine, we prove that the diagnosis system of engine valvevibration fault which is based on the time-frequency analysis and wavelet analysis candiagnose the engine valve clearance fault effectively, and the diagnostic method has thesimple, accurate and practical characteristics.