Study On Oil Film Bearing Characteristics For Hydraulic Pump Slipper Pair In Wear Stage

Slipper pair is the pivotal and most vulnerable friction pair in hydraulic pump,oil contamination can lead to wear of slipper pair and then influence the performance of the hydraulic pump.The wear fault of slipper pair is often difficult to find in time because of the sealing of the hydraulic pump structure,due to the lack of knowledge about fault mechanism,the accuracy of fault diagnosis and condition assessment of hydraulic pump has been at a low level.Therefore,it is of great significance for the accurate diagnosis of the early failure of the hydraulic pump and the effective assessment of the health state to analysis the influence of wear fault of slipper pair on the performance of hydraulic pump and reveal the instability and failure mechanism of the hydraulic pump’s performance.In this paper,the method of combining theory,simulation and experiment is adopted to reveal the instability and failure mechanism of the hydraulic pump’s performance by researching the oil film bearing characteristics of slipper pair during wear process.The research work in this paper is carried out as follows:First,the theoretical model is established.The mathematical description equation of the wear quantity and the wear profile of the inner edge of the slipper are given by analyzing the form of wear fault in the actual working process of the slipper,then the structural parameters of the bottom of the slipper are defined and the wear model of the slipper pair is established.Combined with the wear model of slipper pair and the instantaneous change model of the piston chamber pressure,the oil film bearing characteristic equation of the wear process of the slipper pair is established.According to the oil film bearing characteristics of the slipper pair in wear fault process,the performance instability and the critical point of hydraulic pump are calculated.The corresponding relationship between the leakage flow of the hydraulic pump,the outlet pressure of the pump and the wear of slipper is obtained by numerical method.Then,the simulation verification is carried out.Taking the pressure change law of plunger cavity in the theoretical model as the boundary condition and carrying out the two-dimensional fluid simulation analysis method,the thickness of slipper pair oil film thickness corresponding to the different slipper wear quantity under the force balance condition is found.The three-dimensional simulation model of oil film thickness is established based on the two-dimensional simulation analysis.The oil film bearing characteristics and the change law of the leakage flow of the hydraulic pump are obtained by using the three-dimensional fluid simulation analysis method.The simulation results and theoretical results are analyzed,compared and verified.Finally,test and summary.According to the theoretical calculation and simulation analysis,the range of the wear threshold of the slipper pair is obtained,the parameters of the test sample are determined,and the experiment sample is made by the artificial fault simulation method.Through the test of the leakage flow of the hydraulic pump and the pressure of the pump outlet,the experimental results are compared with the theoretical and simulation results,the results of the study is proved to be correct.The research results can enrich the knowledge of the failure mechanism of hydraulic pump,and provide a scientific reference for the health assessment and fault diagnosis of hydraulic pump.