中文摘要：

齿轮轮齿发生早期裂纹时，裂纹故障信号卜分微弱。为了有效提取早期裂纹故障特征，文中提出基于经验模式分解（empirical mode decomposition，EMD）的早期故障诊断方法。该方法首先去除振动信号中的啮合基频及其谐波成分，得到残余信号，然后针对残余信号进行基于EMD解调分析和处理。仿真及工程实例分析结果表明，所提方法能成功地将齿轮早期裂纹故障信息从复杂的振动中提取出来，更有利于及早发现故障，并判断故障的严重程度。

英文摘要：

Gear tooth crack fault signal is very weak when the crack is in early stage. To extract early gear tooth crack fault feature effectively, an early fault diagnosis method is put forward based on the empirical mode decomposition （EMD）. In this method, the gear meshing harmonics are first removed from the vibration signal to generate the residual signal. The residual signal is then analyzed by using the EMD demodulation method. Simulation results and actual engineering diagnosis example demonstrate that the demodulation analysis method proposed can extract the early crack fault feature of gear from complicated vibration signals successfully. It is more favourable to detect the early fault and judge the fault degree.