Fault Diagnosis For Axial Piston Pumps Based On Signal De-noising And Teager Energy Operator Demodulation

Many kinds of signals carry a great deal of information representing the axial piston pump’s health conditions.However,in the working condition,the useful information are often contaminated and modulated by the presence of heavy background noises and periodic impulses which are caused by inherent working mode of piston pumps.To solve this problem,the method of signal de-noising and Teager energy operator(TEO) demodulation is proposed to detect several kinds of faults in axial piston pumps.The main contributions and research contents are given as follows:1.Aiming at the fault feature extraction for weak damages,based on the Walsh transform and soft-threshold de-noising principle,a method called Walsh transform soft-threshold de-noising is proposed.This de-noising method can effectively weaken the background noise and improve the accuracy of fault diagnosis.Compared with the de-noising method of wavelet transform and the ensemble empirical mode decomposition(EEMD),this method is faster to calculate.Because the TEO has a higher resolution than Hilbert envelope demodulation and can extract weak fault features effectively.After de-nosing,TEO is used to demodulate the amplitude-modulated signal.2.The fault characteristics of axial piston pump will be polluted not only by the background noise but also by the natural periodic pulse interference caused by inherent working mode of axial piston pump.Aiming at this problem,the improved clustering-based segmentation and L-Kurtosis de-noising method is proposed.Unlike the traditional clustering-based segmentation method,the improved version is a two-cycle one,combining the TEO demodulation,fault features are extracted out of the background noise and nature periodic impulses efficiently.3.The engineering application researches for the fault diagnosis of axial piston pump are carried out.The fault diagnosis experimental system for axial piston pump is established relying on an internship company.Through a large number of experimental and applied research,two specific methods based on signal de-noising and TEO demodulation are applied to the faults diagnosis of several types of parts in axial piston pumps.