Study On Flow-resistance Characteristics And Responsiveness Of Textured Directional Valve

In order to optimize the working performance of the reversing valve,Domestic and foreign scholars have carried out research on hydraulic clamping force,fluid force and friction of reversing valve,and proposed various optimization schemes.In this paper,the surface texturing technology is introduced into the reversing valve for optimization design,and the influence of micro-texture on the performance of the reversing valve is studied.The main research contents include:(1)Experimental research and numerical studies were carried out on the flow-resistance characteristics of the textured valve.Through the leakage experiment of the textured valve and the ordinary valve under different oil supply pressures,the influence of the textured surface of the spool on the leakage in the reversing valve was studied,and the viewpoint that the textured surface has the flow-resistance characteristic was proposed.Through the numerical study of the textured gap fluid domain,the flow-resistance mechanism of the textured surface is obtained,and the mechanism of the oil supply pressure affecting flow-resistance characteristic of the textured surface is explained.(2)Experimental studies and numerical studies have been carried out on the responsiveness of textured valve.Through the experimental study on the vibration characteristics of the textured valve and the ordinary valve under different oil supply pressures,the influence of the textured surface of the spool on the vibration characteristics of the reversing valve was studied.The idea that the textured surface can improve the responsiveness of the hydraulic system is proposed.Through the numerical study on the textured gap fluid domain,it is concluded that the textured surface affects the vibration of the spool by affecting the fluid resistance,frictional resistance and fluid stiffness of the reversing valve vibration system.Furthermore,the responsiveness of the reversing valve and the responsiveness of the hydraulic system are affected.(3)Numerical studies on the effects of micro-textures of different shapes and sizes on the flow-resistance characteristic and responsiveness of textured valves were carried out.The effects of three factors of shape,area ratio and width-height ratio of micro-texture on the leakage,dynamic pressure effect and near wall friction of the textured surface are analyzed,which provides an idea for the optimal design of the flow-resistance characteristic and responsiveness of the textured valve.Combining the experimental results with the numerical results,the following conclusions are drawn:(1)When the gap fluid domain reaches the micron level,the micro-texture,which placed on the near-wall surface of the textured spool,will cause the velocity of the fluid to oscillate and affects the entire fluid domain,thereby creating a flow-resistance action.However,as the oil supply pressure increases,the fluid becomes easily invaded into pits,and the flow-resistance action of the textured surface gradually weakens until it disappears.(2)The textured valve affects the friction damping,fluid damping and fluid stiffness during the vibration of the spool by changing the fluid resistance and flow force.Furthermore,by affecting the vibration amplitude and vibration stabilization time of the spool,the responsiveness of the reversing valve and even the responsiveness of the entire hydraulic system are affected.(3)The micro-texture of different shapes,width-height ratios and area ratios will cause leakage,dynamic pressure effect and near wall friction of the textured surface,which will affect the flow-resistance characteristics and responsiveness of the textured valve.As far as the shape of the micro-texture is concerned,it is not possible to conclude which shape of the micro-texture has a significant improvement in the flow-resistance characteristics and responsiveness of the textured valve.However,in terms of improving the flow-resistance characteristics and responsiveness of the texture valve,the introduction of the polygon is significantly better than the circular shape.In terms of the area ratio of the micro-texture,the area ratio of 25%to 36%has a significant advantage in improving the flow-resistance characteristics and responsiveness of the textured valve.In terms of the width-height ratio of the micro-texture,the aspect ratio of 0.4-0.6 has significant advantages in improving the flow resistance and responsiveness of the textured valve.