A new coupled dynamic model to study the vibration and lubrication characteristics of slipper/swash-plate interface in an axial piston pump

A new integrated dynamic model is developed by examining the motion equations and kinematics of the slipper and piston, coupled with the lubrication properties of the oil film. This model simultaneously addresses the dynamic vibrations of the slipper and piston along with the characteristics of the oil film lubrication. To validate this model, a test apparatus is constructed. It is found that the power loss simulated from the slipper pair comprises approximately 20-65% of the measured power loss, while the simulated leakage flow rate generated by the slipper pair constitutes around 30-50% of the measured leakage flow rate. The vibration responses of the slipper and piston, as well as the oil film lubrication characteristics, are analyzed under various load pressures and speeds. The first several harmonics of the differences in the vibration responses of the piston and slipper and the central oil film thickness between the slipper and swash plate are in the magnitude of micrometer. The relative motions between the piston and slipper influence the oil film thickness, and the nonlinear attributes of the oil film impact the vibration behaviors of the piston and slipper. The dynamic central oil film thickness at harmonic frequencies decreases with increasing load pressure, while most harmonic-related oil film thickness increases with rising speed.