Numerical Simulation of a Slipper Model with Multi-Lands and Grooves for Hydraulic Piston Pumps and Motors in Mixed Lubrication

Toshiharu Kazama

doi:10.3390/lubricants7070055

Abstract

A theoretical model of a slipper with multi-lands and multi-grooves for swashplate type axial piston pumps and motors was established, including surface interactions. Further, a numerical simulation was conducted under an unsteady state and mixed lubrication conditions. Four model configurations were considered: A slipper with a single main land; a slipper with inner and main lands and a groove; a slipper with outer and main lands and a groove; and a slipper with inner, main, and outer lands with two grooves. Numerical solutions were obtained across a wide range of operating conditions in terms of center clearance, pad attitude, contact pressure, flow rate, friction torque, power loss, and stiffness. The motion and characteristics were differentiated into two groups: Slippers with a single-land and an annex inner-land; and slippers with an annex outer-land and a triple-land. The single-land and annex inner-land slippers exhibited smaller pad swing, whereas the triple-land and annex outer-land slippers reduced contact pressure and power loss.

Highlights

Hydraulic systems have the advantages of high power density and high frequency response, and they are used widely in areas such machinery construction, aeronautical equipment, and complex manufacturing
Hydraulic pumps and motors are positive displacement machines, which are prime components that play a role in the transformation of mechanical energy into fluid pressure, and vice versa
The effects of heat generation at the interface [14], e lastic deformation of the parts [15], changes in the fluid properties [16] have not been negligible for actual slippers in hydraulic piston machinery, this paper focused on multi-land slippers in mixed lubrication

Summary

Introduction

Hydraulic systems have the advantages of high power density and high frequency response, and they are used widely in areas such machinery construction, aeronautical equipment, and complex manufacturing. Hydraulic pumps and motors are positive displacement machines, which are prime components that play a role in the transformation of mechanical energy into fluid pressure, and vice versa. The swashplate type axial piston machine is a common hydraulic pump/motor because of its high pressure operation, high efficiency characteristics, and variable displacement mechanism. The swashplate axial piston pump/motor has three sliding parts: Interference between the pistons and cylinder bores; interference between the valve plate and cylinder block; and interference between the slippers and swashplate. The friction and leakage at parts having bearing and sealing functions strongly affect the efficiency and performance of the pump/motor. Wear and seizure at these parts influence reliability and durability; the tribological characteristics of the pump/motor are very important

Methods

Results

Discussion

Conclusion