Research on the Influence of Piston Pair Wear on Pump Output Characteristics of Axial Piston Pump Under Multiple Working Conditions

To clarify the nonlinear degradation of volumetric performance caused by piston–cylinder wear in axial piston pumps under multiple operating conditions, this study develops an integrated framework linking local wear-induced leakage to whole-pump output characteristics. A mathematical model incorporating piston kinematics, eccentric-clearance leakage, chamber-pressure dynamics, and whole-pump flow was established and implemented in Amesim. A four-factor mixed-level orthogonal design and analysis of variance were then employed to quantify the effects of wear clearance, eccentricity, load pressure, and shaft rotational speed. The results show that their contributions to volumetric efficiency follow the order: motor rotational speed > load pressure > wear clearance > eccentricity, whereas load pressure is the dominant factor affecting pressure ripple. A wear clearance of approximately 0.1 mm marks the onset of pronounced leakage-induced performance degradation. At this clearance and a load pressure of 20 MPa, increasing the rotational speed from 500 to 3000 r/min improves the volumetric efficiency from 67.48% to 94.44%, with an average increase of 5.39 percentage points per 500 r/min. Comparative experiments on normal and artificially worn pumps were conducted to validate the model. The measured motor-speed slip under high-load conditions was incorporated to correct the theoretical displacement and distinguish speed-induced flow reduction from internal leakage. After correction, the maximum relative error between the simulated and experimental results was below 3.7%. The proposed framework integrates mechanism-based leakage modeling, multi-factor contribution analysis, and speed-corrected experimental validation, providing a theoretical basis for the wear assessment, piston–cylinder clearance design, and flow compensation of axial piston pumps under variable operating conditions.