基于特征参数和功率谱分析的液压滑阀内漏声发射检测实验研究

内泄漏直接影响液压系统的工作效率,常用的检测方法主观性强、效率低。以5组通径16 mm的三位四通换向滑阀为研究对象,设计并搭建了液压滑阀内泄漏声发射检测实验台。对比声发射信号的幅值域参数大小和响应时间,确定了最佳测量点。结合实验数据,找到了压力、间隙高度对幅值域特征参数的影响规律。运用AR功率谱提取信号的特征频率,发现滑阀内漏的声发射信号基频为40 kHz,泄漏量越大,特征频率越向低频方向偏移;特征频率呈现倍频的关系,内漏滑阀的功率谱曲线有小幅波动,正常滑阀功率谱曲线光滑。所得实验数据和结论对构建滑阀内漏诊断数据库具有重要意义。

Experimental Study Based on Characteristic Parameters and Power Spectrum Analysis for Acoustic Emission Detection of Hydraulic Spool Valve Internal Leakage

Internal leakage directly affects efficiency of hydraulic system, and common detection methods are subjective and inefficient. Five groups of 16 mm diameter three-position four-way directional slide valves are taken as the research object, and an acoustic emission (AE) test rig for detecting internal leakage of hydraulic slide valves is designed and built. Comparing amplitude range parameter and response time of AE signal, we determine the best measuring point. Combined with the experimental data, the influence rule of pressure and clearance height on amplitude domain characteristic parameters is found. The AR power spectrum is used to extract the characteristic frequency of the signal. It is found that the fundamental frequency of the AE signal is 40 kHz, and the larger the leakage, the more the characteristic frequency shifts to the low frequency. The characteristic frequency shows the relation of frequency doubling, and the power spectrum curve of leaky slide valve has a slight fluctuation, and the normal slide valve power spectrum curve is smooth. The experimental data and spectrum analysis conclusions are of great significance for construction of diagnostic database for spool valve leakage.