Oil film lubrication state analysis of piston pair in piston pump based on coupling characteristics of the fluid thermal structure

The axial piston pump will be seriously damaged when the poor oil film lubrication. Therefore, considering the influence of hydraulic oil viscosity on oil film pressure and oil film temperature, oil film heat transfer to the piston and elastic deformation caused by piston thermal expansion, a fluid thermal structure coupling model of piston pair of axial piston pump was established. An experimental platform was built to measure the oil film characteristic data throughout the cycle, and the multi-physical field test, including temperature, pressure and thickness at multiple locations of the oil film of the piston pair was realized. The effects of oil temperature, spindle speed and load pressure on the lubrication of piston pair were studied and analyzed. The working condition parameter range corresponding to the significant reduction of oil film lubrication performance was obtained, which provides a basis for predicting the lubrication failure of the piston pump.