Optimization study of low lateral force in eccentric ball-piston pumps

Abstract

Eccentric ball piston pump is a high power density hydraulic component. In this paper, a low lateral force design method for an eccentric ball-piston pump is proposed to reduce the lateral force between the ball and the cylinder by slightly inclination of the cylinder, and a mathematical model of the method is established. An experimental platform of eccentric ball-piston pump for evaluating the performance of cylinder block slightly inclination was established to verify the effect of slightly inclined cylinder block on the volumetric efficiency and mechanical efficiency of the pump. According to the experimental results of the prototype, the tilting angle from 0° to 3°, the lateral force between the ball piston and the cylinder decreases and then increases, the volumetric efficiency of the pump increases and then decreases, and the mechanical efficiency improves continuously. 3° of cylinder tilting angle reduces the friction torque by 2.63 Nm compared with the un-tilted cylinder, and the mechanical efficiency improves by 7.12%. 2° of cylinder tilting angle reduces the leakage volume by 0.475 L/min compared with the un-tilted cylinder, and the volumetric efficiency improves by 3.67%. This study is instructive for the study of high efficiency of eccentric ball piston pumps.