Research On Lubrication Characteristic Of Cylinder/valve Plate Pair In The Axial Piston Pump

Due to its high power density,flexible components and other advantages,hydraulic transmission is a main form of fluid transmission.So hydraulic transmission is widely used in mobile machinery and equipment.And axial piston pump is the core components of hydraulic transmission system.Cylinder/valve plate pair is the friction pair with the largest contact area,resulting in the most prone to wear and leak.Cylinder/valve plate pair is one the most critical friction pair in axial piston pump,it plays an important role in its work performance.Based on this background,the cylinder/valve plate pair in the axial piston pump is taken as the research object in this paper,aiming to study the method of slowing down wear and the attitude of the cylinder.For the cylinder/valve plate pair in the axial piston pump prone to wear,the auxiliary support belt is machined rectangular groove to in order to improve the oil film support characteristic.The dynamic pressure support characteristics with the grooved flow distribution face of cylinder/valve plate in the axial piston pump is studied in this paper.A theoretical dynamic pressure model is established.By applying the finite volume method to numerical discretization according to the law of conservation of flow,the distribution law of dynamic pressure and the effect of support with the grooved face are analyzed,the change law of the friction coefficient under the whole film lubrication condition is obtained as well.A test rig is built to verify the test results.The traditional design method ignores the influence of the dynamic pressure in the cylinder/valve plate pair.The motion of the cylinder relative to the distribution plate can't be intuitively reflected,the characteristic easy to wear of the cylinder/valve plate pair can't be solved either.The motion of the cylinder which is lack of constraints in the axial piston pump is analyzed.The complex lubrication of the cylinder/valve plate pair is simplified into a three-free stiffness-damping cylinder dynamic system.A three-degree-of-freedom cylinder dynamic model is established.The effects of dynamic pressure,working speed,working pressure and oil temperature on the lubrication of the cylinder/valve plate pair are discussed.Finally,the leakage and friction characteristics of the distribution pair are analyzed too.In the structure design of the cylinder/valve plate pair,different structural parameters to the lubrication of the cylinder/valve plate pair is unknown.Three different structural parameters of cylinder distribution face are given.The dynamic behavior of the cylinder distribution face in steady state is analyzed by using the existing cylinder dynamics model and the experiment.So the lubrication performance of the different cylinder distribution faces are studied.The results show that when the plunger diameter and the plunger indexing circle are determined,the neutral structure cylinder distribution face has good characteristics on its lubrication performance and leakage characteristics.Neutral structure cylinder distribution face can be considered when designing the distribution structure under certain conditions.Finally,the influencing factors of the structure in the cylinder/valve plate pair is given,which provides the theoretical guidance for the optimization of the cylinder/valve plate pair structure design.