柴油机缸盖振动信号的小波包分解与诊断方法研究

研究了柴油机缸盖表面振动信号的时域、频域和循环波动特性，揭示了它的非平稳时变特点，提出了从振动信号的小波包分解系数中实现整循环征兆提取和故障识别的方法。实际及分析结果表明了该方法的可行性和有效性，这对其它复杂机械的振动诊断同样具有参考价值。

Fault Diagnosis for Diesel Engines by Wavelet Packets Analysis of Vibration Signal Measured on Cylinder Head

In the paper an unique technique for diesel engine diagnosis by wavelet packets （WP） analysis is proposed．The characteristics of the vibration signal in time-domain，frequency-domain and cycle-by-cycle fluctuation measured on the cylinder head are analyzed，revealing its essentially non-stationary and time-varying properties．An improved algorithm for WP decomposition is put forward，which overcomes the existing frequency aliasing．By using such algorithm，the diagnostic features are constructed easily from the decomposed WP coefficients of the vibration signal synchronously sampled during a full working cycle．The experimental results show that this technique is simple in implementaion and may provide practical utility for vibration diagnosis in diesel engines as well as in other complex machines．