中文摘要：

该研究旨在解决液压缸内泄漏故障诊断中敏感故障特征的选择问题。分析了液压缸内泄漏故障的机理，阐明了泄漏对液压缸工作腔动态压力的影响，提出了一种通过调节旁路节流阀的开口度模拟液压缸内泄漏的实验方法。实验结果分析表明，采用小波包分解对液压缸工作腔的压力信号进行分析，最终确定用压力信号的小波包最低子带能量、小波包子带能量熵和小波包子带能量方差作为液压缸内泄漏故障的敏感特征量。研究结果对液压缸的泄漏故障诊断及健康状态评估具有理论指导意义。

英文摘要：

To solve the problem of sensitive characteristic parameter selection for the hydraulic cylinder internal leakage fault, the mechanism of the leakage fault is analyzed. And the effects of leakage on the dynamic pressure of the hydraulic cylinder working chamber are clarified. Then, a method is proposed to simulate the internal leakage of the hydraulic cylinder by adjusting the opening degree of the bypass throttle valve. The method of wavelet packet decomposition is used to analyze the pressure signals of the hydraulic cylinder working chamber. And the lowest sub-band wavelet packet energy, the wavelet packet sub-band energy entropy and the wavelet packet sub-band en- ergy variance of the pressure signals are ultimately determined as sensitive characteristic parameters for the internal leakage fault. The results have theoretical guidance for the leakage fault diagnosis and the health state assessment of the hydraulic cylinder.