Influence of hydraulic oil physical property parameters on the lubrication characteristics of piston pairs

SUN Guangming; SUN Jian; LI Guoxiang; BAI Shuzhan; ZHENG Liang; SHI Guangqiang

doi:10.19471/j.cnki.1673-6397.2025.06.005

Abstract：To investigate the effects of hydraulic oil physical property parameters on the oil film pressure,surface elastic deformation,viscous friction,and hydraulic oil leakage of the piston pair,an axial piston pair oil film pressure equation and thickness equation are established.The oil film is discretized using the staggered grid method,and the oil film pressure,thickness,and surface elastic deformation of the piston pair are solved using MATLAB and Abaqus software,respectively.Python programming is used for real-time data exchange between MATLAB and Abaqus,achieving fluid solid coupling calculation of the piston pair oil film.A simplified stiffness model and Roelands viscosity temperature viscosity pressure equation for piston pair oil are established,and the influence of piston pair oil stiffness and viscosity on the lubrication characteristics of piston pair oil film are analyzed.The results show that the oil film stiffness has a significant impact on the oil film pressure of the piston pair.The oil film stiffness increases from 29 420 N/mm to 46 667 N/mm,and the average peak pressure of the piston pair oil film in the oil discharge are increases from 208.24 MPa to 259.93 MPa.However,the effect of the oil film stiffness on the surface elastic deformation,axial viscous friction force,and leakage of the piston pair is relatively small.The viscosity of hydraulic oil has a significant impact on the oil film pressure,viscous friction force,and leakage rate of the piston pair,but has little effect on the elastic deformation of the piston pair surface.The viscosity of hydraulic oil increases from 0.009 4 Pa·s to 0.022 5 Pa·s,and the average peak pressure of the piston pair oil film in the oil discharge are increases by 28.4％.The axial peak viscous friction force in the oil suction are increases by 154.8％,and the peak leakage rate in the oil discharge are decreases by 66.8％.