Friction Consumption and Leakage Performance of Step Piston in a Novel Synchronous Lubrication Radial Piston Pump

Abstract To alleviate the wear caused by insufficient lubrication of the slipper and piston pair due to the expansion of the piston pump speed range, a novel synchronous lubrication structure with step piston was proposed, which can generate high-pressure oil to lubricate the friction pair while discharging the working medium synchronously. However, the step structure inevitably influences the film's characteristics and has unclear effects on friction and leakage performance. Therefore, the lubrication and deformation model of the step piston, verified by comparison with classical literature, is established by combining the finite difference method and the finite element method. The influence of load pressure, shaft speed, and step parameters on its tribological characteristics was further analyzed. The results show that the local step-bearing effect is produced near the piston step, but at the expense of the decreased upstream fluid pressure. The matching length reduction caused by the step piston does not aggravate the piston eccentricity but alleviates the eccentricity and leakage. The friction consumption and leakage are positively correlated with the load pressure and shaft speed; the step-bearing effect and the piston anti-capsizing ability can be significantly improved with a smaller step height, which is also conducive to reducing leakage but increasing friction consumption. There is an optimal step height to increase the pump efficiency.