Study On Performance Of Slipper Bearing In Hydraulic Axial Piston Pump In High-pressure And High-speed

In order to improve work performance of slipper bearings in axial piston pump, thecenter shallow oil cavity in the same order of magtitude as the film thickness was appliedon the lower surface of slipper bearing to improve the lubrication condition by the strongerhydrodynamic effect of step surface, the pressure distribution and hydrodynamic momentwas improved by the circle shape of the center shallaow oil cavity. The new slipper bearingwas named as “combined cavity” slipper bearing. Through theoretical analysis andnumberical calculation, the work performances of common slipper bearing and combinedcavity slipper bearing have been studied, which includes lubricant characteristics,hydrostatic supporting adaptativity and the work pose of slipper bearing.Through analysis on the key calcaulation thought of the pressure distributioncalculation methode such as the finite volume metod and the finite difference metod basedon Reynolds equation, the coincidence in mathematical form between flow chargecalculation model of the representative volum in classical method and the the pressuredifference-flow model of parallel plat gap was found, then based on liquid resistance theory,the “equallent hight” was proposed, classical calculation of pressure distribution wasimproved through the flow charge model conducted based on the “equallent hight”.Pressure distribution calculated by classical method and the improved method weredcompared to indicate the improved method reasonal and more precise, and effects onpressure by squeezing effect of lubricant film, providing oil pressure, tilting angle andsliding speed were studied through numberical simulation. The result indicated that effectbetween hydrostatic and hydrodynamic was almost little in the present numbericalcalculation, pressure distribution was affected less by providing oil pressure and apparentlygreater by squeezing effect of lubricant film, tilting angle and sliding speed.The hydrostatic supporting adaptativity model was developed through combining theimproved numberical model of pressure distribution and the pressure difference-flow modelof little hole damp based on the mass conservation principle, by which the pressure ofcenter cavity and pressure distribution in seal area can be calculated in the meanwhile.Through real-time calculating the pressure of center cavity, the hydrostatic supportingadaptativity was studied, and through the hydrostatic supporting adaptativity model, thechange law of the pressure of center cavity with center film thickness, damp-hole diameter, providing oil pressure, oil viscosity, titing and pump speed was studied. The study indicatedthat the mass conservation principle was the key law of the hydrostatic supportingadaptativity, which was realized by real-time changing of pressure difference at the twoends of little hole; the pressure in center cavity changed in real time to maitaine the balancebetween the lift force and the load force; the hydrostatic supporting was the importantperformance of the hydrostatic supporting system, the range and sensity of pressurechanging in center cavity was the important indexes and evaluating standard.The “combined cavity” slipper bearing was made through applying the center shallowoil cavity in the same order of magtitude as the film thickness on the lower surface ofslipper bearing. Through the above mathematical model, the pressure field cgaracteristicsand the hydrostatic supporting adaptativity were calculated, in which the black-weightapproach was applied to deal with the incoincidence of mesh and the shallow cavityboundary. It was included that the pressure distribution and the hydrostatic supportingadaptative had to been improved to improve performance of slipper, applying of theshallow cavity improved hydrodynamic and moment, anti-overturning ability and thehydrostatic supporting adaptativity were improved.Finally, through the study on the effect of the depth and radius on the pressuredistribution of the “combined cavity” slipper bearing, the radius of the deep cavity, theshallow cavity and the outside of the “combined cavity” slipper bearing were determined asthe preparative optimization variables. And then dynamic equilibrium model of slipper wasdetermined as constraint conditions, loss of power was determined as objective function,the standard PSO was applied to optimazed the preparative optimization variables. To savecost of time and reduce workload, several representative work position of slipper wereselected to optimization calculate, and the range of the preparative optimization variableswas given baed on the calculation results.