Performance Degradation Assessment Method Of Hydraulic Pump Integrated With CEEMD And VPMCD

As the power source of the hydraulic system,the performance of the hydraulic pump will directly affect the reliability of the operation of the whole hydraulic system.Therefore,it is of great significance to monitor the running state and assess the performance degradation degree of the hydraulic pump.In order to better characterize the performance degradation of the hydraulic pump,this paper studied the hydraulic pump degradation feature extraction method and performance degradation assessment method.Before performance degradation assessment,the degradation characteristics of hydraulic pump should be extracted first.As the hydraulic pump vibration signal is nonlinear,non-stationary and low SNR,after comparing Empirical Mode Decomposition(EMD),Ensemble empirical mode decomposition(EEMD)and Complete Ensemble Empirical Mode Decomposition(CEEMD),this paper compared the performances of approximate entropy(ApEn),sample entropy(SampEn)and fuzzy entropy(FuzzyEn),and then a feature extraction method based on CEEMD,FuzzyEn was proposed.introduced into the hydraulic pump degradation state recognition.The VPMCD method was introduced to classify and identify the degraded feature information so that the performance degradation assessment of the hydraulic pump was realized.Firstly,the vibration signals of the hydraulic pump were decomposed into several IMF(Intrinsic Mode Function)with CEEMD.Secondly,the correlation between each IMF and the original signal was calculated,and the high correlation components were selected to obtain their fuzzy entropy,then the degradation characteristics were obtained.Thirdly,the VPMCD method was used to establish predictive model for all eigenvalues of training samples in each state,and then the test samples were identified.This method was verified by rolling bearing data published by Case Western Reserve University,and the recognition accuracy rate reached one hundred percent.Finally,the degradation process of the axial piston pump under different faults was simulated in the laboratory.The performance degradation of the hydraulic pump was evaluated by the method proposed in this paper,and the feasibility and effectiveness of the method were verified by the results.