Research On Anti-eccentric Load Performance Of Hydrostatic Bearing Type Hydraulic Cylinder

Hydraulic-driven quadruped robot,as a typical bionic walking robot,has attracted much attention because of its high mobility,strong load capacity and smooth movement.As its power components and actuators,hydraulic cylinders require low friction,good lateral load resistance and high speed motion.Conventional hydraulic cylinders are usually sealed with seals,which not only increases the frictional resistance of the piston rod during movement,but also reduces the sealing effect of the seal when the piston rod is subjected to a certain radial load,and the control accuracy and stability of the hydraulic cylinder are affected.Therefore,according to the principle of hydrostatic bearing,the hydraulic cylinder with hydrostatic bearing technology has the performance of stable starting,low friction and large radial load.In this paper,the hydrostatic bearing structure of hydraulic cylinder and its anti-eccentric load performance are studied.The main work is as follows:Firstly,as the core component of the hydrostatic bearing structure cylinder,the guide sleeve is designed for its hydrostatic bearing structure.The anti-eccentric load capacity,friction and leakage of hydrostatic bearing are important indexes to measure the performance of hydrostatic bearing structure hydraulic cylinders.In this paper,the bridge method of the circuit is used to analyze the bearing principle of the hydrostatic bearing structure,and the mathematical model of the bearing capacity and oil film stiffness of the hydrostatic bearing guide sleeve is analyzed and derived.The friction and leakage of the hydrostatic bearing structure are analyzed.Secondly,the hydrostatic bearing oil film model of rectangular oil cavity and Ishaped oil cavity is proposed and established for the hydraulic cylinder guide sleeve structure.Based on the numerical simulation of Fluent,The pressure field performance of hydrostatic support oil film are analyzed,and the ability of the hydrostatic bearing guide sleeve to resist the displacement of the piston rod in the radial direction is analyzed.The performance of the oil film of the rectangular and Ishaped oil cavity of the hydrostatic bearing guide sleeve are analyzed and compared.The relationship between piston rod moving speed,eccentricity,oil flow rate and bearing capacity,friction and leakage of hydrostatic bearing seal is studied.Finally,aiming at the anti-eccentric load characteristic of hydrostatic bearing structure of hydraulic cylinder,a test bench was built to measure and analyze the eccentricity of piston rod.The eddy current sensor is used to measure the eccentric distance of the piston rod during the maximum stroke,and analysis of anti-eccentric load ability of guide sleeve of hydrostatic bearing.And then,the anti-eccentric load ability of rectangular oil cavity and I-shaped oil cavity under different eccentric load weight is analyzed to verify the accuracy and rationality of theoretical analysis and simulation.In this paper,through the research of the anti-eccentric load performance of hydrostatic bearing type hydraulic cylinder,the mathematical model of the hydrostatic bearing structure of the guide sleeve of the hydraulic cylinder is established,and the mechanism of the anti-eccentric load performance of hydrostatic bearing hydraulic cylinder is analyzed,which provides a theoretical reference for the research of the anti-eccentric load performance of hydrostatic bearing hydraulic cylinder.