Influence Of Oil Properties On The Performance Of Axial Piston Pump And Fault Mechanism Of Port Plat Pairs

With the rapid,high-power,high-precisiondevelopment of hydraulic system,the piston pump is widely used into high-speed and high-pressure environment.Such special operation condition lead to the performance degradation and serious vibration,noise as well as leakage,which does not only affect the performance of pump,but also shortens the service life and restricts the application of pump.Therefore,developing the research of the mechanism of vibration and noise reduction is the hot issue and research focus in the field.The various operating states of the piston pump are shown by vibration and noise.The flow pulsation,as the key research content of vibration and noise reduction,is not only related to the structural parameters,the system parameters and the Operating parameters,but it is also changed by the oil proporties and running states of port plate pairs.With the development of computational fluid dynamics(CFD),CFD has been widely used in the internal flow-field simulation analysis of hydraulic components and hydraulic systems.Therefore,combined with the theoretical analysis,numerical simulation and testing,the influence of oil proporties on performance of pump and the fault mechanism of port plate pairs are stuied in this work,which provides the theoretical foundation for the research on the performance degradation,fault mechanism of the piston pump.The main contents of this work are shown as follows:(1)Based on the working principle of axial piston pump,the internal flow-field model of HPV-55 axial piston pump is established and simulated by Solidworks software,C language,Gambit software and FLUENT.By considering the nonlinear parameters of oil such as elastic modulus,viscosity and so on,the variation of the internal flow field and output characteristics of the axial piston pump are obtained.In addition,The simulation model of piston pump is validated by testing,which provides a model-simulation platform to research on the output characteristics of piston pump and the failure mechanism of port plate pairs.(2)The influence mechanism of the compressibility and viscosity of the oil on the volumetric efficiency of the plunger pump are studied.Under the assumption that the effective volume elastic modulus of the oil is constant,the mathematical model of the volumetric efficiency of the piston pump including the oil compressibility and viscosity is deduced.Moreover,the influence of the compressibility and the viscosity of the oil on the actual flow,the compressed flow and the leakage flow of the oil pump outlet are carried out under the same structural parameters.The effectiveness of the mechanism is validated by experiments,and the results show that the loss of compressed flow is enhanced with the increasement of speed and load.In particularly,the inflence of oil viscosity is the greatest one.In addition,when the load pressure exceeds a certain value,the oil pressure characteristics of the volumetric efficiency of the impact can not be ignored.(3)The influence of the different properties of oil on the flow pulsation of piston pump flow is studied.The effects of effective bulk modulus on the flow pulsation,leakage pulasation and compression flow are analyzed are studied when the effective bulk modulus is constant or variable.In additon,The influence of the compressibility,viscosity,gas content and flow state of the oil on the pulsation of the flow pulsation is taken into account.The simulation and test results show that the compressive loss of oil increased with the increase of gas content and temperature.The influence of oil compression,viscosity,gas content and flow rate on flow rate is 86.8%,9.45%,3.59% %,0.16%.(4)The influenc of port plate pairs fault on the output characteristics of the piston pump is studied.Based on the influence of the nonlinear variation of oil properties on the pump output characteristics,the failure evolution model of different distribution plate wear and different oil film thickness changes was established.The effects of speed and load on the flow rate of the flow Pulsating and noise.The simulation results show that the fluid noise of the piston pump increases with the increase of the wear degree of the distribution plate and decreases with the increase of the oil film thickness which is benefit to identify the fault characteristics of the distribution pair.