A Threshold Adaptive Fault Diagnosis Method For Axial Piston Pump Under Varying Operation Condition

Hydraulic equipment plays an important role in applying into lots of fields such as construction machine,marine,aerospace and so on.The piston pump is the source of hydraulic system,and its performance relates to the safety and operation quality of equipment.Therefore,it is important to research on the fault diagnosis method of piston pump.However,because of oil pollution and running under terrible environment,the fault of piston pump generated frequently.Especially,during the varying operation condition,the fault features are more obvious,meanwhile it usually expresses non-stationary characteristics,which leads to uselessness of the traditional fault diagnosis method.This work studied the threshold adaptive fault diagnosis method.It is attempt to recognize the wear of port plate for piston pump under varying condition with the varying threshold that is altered as the operation condition.The achievement of the work is expected to provide effective method for the fault diagnosis of piston pump.The main contents of this work are presented as follows.(1)Combined with the construction and operation environment of piston pump,the generated mechanism of fault for piston pump is analyzed.Particularly,the changing regular of vibration signals derived from different fault is studied.The relevant results provide the theoretical foundation for the diagnosis of port plate wear.(2)Based on the variation of vibration signal of the piston pump under the constant operation condition and the shortcomings of the traditional fault diagnosis method under the varying operation condition,the quantitative calculation method of the piston pump fault sensitivity is put forward.In this paper,the linear correlation and stability of the time domain characteristics of the vibration signal and the sensitivity to the wear fault of the port plate are studied,and the dimensionless parameter index of the amplitudedomain is analyzed by envelope demodulation.According to the analysis,the RMS Xrms,margin factor CLf and kurtosis Kv of vibration acceleration signal are selected among several statistic features,which provides technical method to quantify the variable condition of piston pump port plate wear fault sensitivity.(3)Based on the experimental platform of fault diagnosis and data collection system using LabVIEW and IPC,the experimental data is captured from the fault pump with the style of Rexroth A10VG45.It is proposed to remove the interference in the collected signal by the method of hardware isolation and software filtering,then,according to the characteristics of the Chebyshev inequality,the fault threshold interval and adaptive threshold curve is set.Finally,the adaptive threshold method is validated by the experiments,and the results show that the proposed method is able to improve the diagnosis accuracy of piston pump with port plate wear under varying speed and changeable load.