Research On Drag And Noise Reduction Of Key Friction Pairs With Non-smooth Surface Of Water Hydraulic Motor

In order to meet the increasing requirements of environmental protection,water hydraulic transmission technology has become an important research direction.Water hydraulic motor,an important executive element of hydraulic transmission,takes fresh water or sea water as working medium.However,water,having poor lubricity and high gasification pressure,makes water hydraulic motors more prone to wear,vibration and noise.To solve this problem,the non-smooth surface is introduced friction pairs of the water hydraulic motor.The main contents of the paper are as follows:Firstly,according to the theory of tribology and dynamics,the wear,vibration and noise of water hydraulic motor is analyzed.The results show that the wear,vibration and noise of water hydraulic motor mainly occur between two friction pairs,piston pair and valve pair clearance.Improving the lubricity of friction pair clearance is the key to reduce resistance and noise.Secondly,the mechanical model of piston pair is established through force analysis,which provides theoretical basis for analyzing the friction force of piston pair.The cylindrical pit surface is designed on the piston,and the finite element analysis model of the piston pair with smooth and non-smooth surface is established according to the actual size and motion of the plunger.The finite element analysis results show that the existence of pit makes the stress distribution more uniform.Then,according to the valve pair model,the corresponding friction pair samples are made,and three different types of pits(hemispheric pit,triangular prism pit and ellipsoid pit)are designed on the end face of the friction pair.The friction and wear experiments are carried out by soaking the sample in seawater.The experimental results show that the existence of the pit can capture the abrasive in the friction process,reduce the abrasive wear and improve the lubrication state of the friction pair.Different pit types have different effects on the friction and wear of the sample,and the wear resistance effect of the ellipsoid pit is the best.At the same time,the finite analysis model is established according to the sample model.The simulation results show that there will be stress concentration near the edge of the pit,which will exacerbate the wear.Finally,in order to further explore the mechanism of drag reduction and noise reduction for non-smooth surfaces,the simplified water film model of valve pair clearance under full lubrication is established,and the flow field,sound field and fluid-solid coupling of water film are simulated by ANSYS.The simulation results show that the non-smooth surface can improve the carrying capacity and stability of the water film,thus reducing the resistance and noise.