Diagnosis Research On The Abnormal Noise Of Engine Crank Bearing Breakdown

Vibration signals that bring by different crank bearing clearances are no stationary and time-variant. It is difficult to early detect and diagnose by means of traditional methods. This thesis first introduces the developing process and common methods on abnormal noise of engine crank bearing breakdown, and then, different clearances of crank bearing of previously designed on EQ6100 model gasoline engine, which vibration signals are got from crank bearing cover and engine block.Basing on the decomposition and reconstruction of wavelet packet to time-variant signal, a time-frequency analysis method based wavelet packet is developed in this paper. It has little disturbed and good time-frequency resolution. Through analyzing and contrasting the traditional signal analysis method of FFT, the result shows that it can reveal the change rules of crank bearing wears clearances and quantitative analysis.