中文摘要：

介绍了采用Hilbert—Huang Transform（HHT）信号分析方法提取柴油机缸盖振动信号中气阀漏气特征的试验研究。通过气阀漏气的故障模拟试验，测量了柴油机气阀不同状态下的缸盖振动信号，分析确定了缸盖振动信号的分析段；运用HHT分析方法提取了气阀漏气时频域故障特征参数。研究发现：当气阀处于正常状态时其振动信号能量主要集中于上止点附近；当气阀处于漏气状态时能量向压缩冲程转移，分布更为均匀。表明：表征能量分布均匀程度的时频熵可以作为气阀漏气故障特征参数。

英文摘要：

Using Hilbert-Huang Transform （HHT） analysis method, the experimental research on extracting the characteristics of valve leakage from the vibration signals of a diesel engine＇s cylinder head is present. The valve leakage faults were simulated, the vibration signals on the cylinder head in the different valve conditions were measured, the analysis sections of the vibration signals were identified, and the characteristic parameters of the valve leakage faults were extracted by using HHT analysis method in frequency domain. It is found that when the valves are in good condition, the vibration signal energies are concentrated in the vicinity of the top dead center （TDC） ; while in the leakage condition, the vibration signal energies are transferred to the compression stroke and the energy distribution is more equal. It is also found that the time-frequency entropy which characterizes the uniformity of the vibration energy dis- tribution can be treated as the characteristic parameters to diagnose the fault of valve leakage.