Optimization of micro-texture in thermo plastic elasto-hydrodynamic lubrication for improving the start-up behavior of the piston/cylinder pair in axial piston pump

The piston/cylinder pair is a critical friction pair that serves to achieve suction and pressure oil functions, significantly influencing the performance of axial piston pumps and representing a major vulnerable point affecting their reliability and service life. This article presents an experimental study of axial piston pump internal leakage, revealing an abnormal increase in leakage during start-up condition. A thermo-fluid-solid oil film properties model is constructed for the start-up condition with plastic cumulative damage in the eccentric attitude of the piston/cylinder pair, and the oil film properties and wear leakage of the axial piston pump are analyzed in comparison under the start-up condition and steady condition, and the validity of the model is verified with the experimental leakage law. The results indicate that under start-up condition, the plastic accumulation of damage in the piston/cylinder pair and the leakage are significantly more severe, which is approximately 1.9 times of the leakage in the steady condition. Thus, a textured surface was developed on the piston. textured design induces a micro-dynamic pressure effect within the oil film throughout the oil suction process. This improvement enhances its load-bearing capacity, leading to a 20 % reduction in wear and a 22 % decrease in leakage. This design effectively enhances the tribological performance of the piston/cylinder pair.