THE TRANSITION OF WEAR AND LEAKAGE CHARACTERISTICS OF THE CYLINDER BLOCK/VALVE PLATE INTERFACE IN A WIDE RANGE OF OPERATING CONDITIONS

In order to take full advantage of the servo motor-driven pump, it usually demands that the axial piston pumps work in a wide range of operating conditions. It inevitably leads to a great change in performance due to the transition of wear and leakage characteristics. In this paper, a mixed lubrication model of the cylinder block/valve plate is established which fully considers the asperity contact and its effect on the lubricating oil flow. The load-bearing and lubrication characteristics such as film thickness, tilt behavior, and leakage flow are investigated under different operating conditions. The simulation results show that the cylinder block/valve plate mainly operates in the mixed lubrication regime. The wear represented by the maximum PV value shows a gradual transition process that varies with the operating conditions. It is more severe under high discharge pressure and high rotating speed. While the leakage flow shows a strong dependence on the tilting angle under low discharge pressure and high rotating speed conditions. It sharply increases with the increase of rotating speed which will lead to an abrupt failure of the axial piston pump.