Study On Lubrication Characteristics And Efficiency Of The Textured Tripod-ball Cage Universal Joint Drive Shaft System

In order to respond to the call of national energy conservation and emission reduction and improve the tribological performance of automobile transmission shaft system,micro-grooves are designed on the main friction surface of the tripod universal coupling and the ball cage universal coupling respectively.The hydrodynamic lubrication characteristics and transmission efficiency of the textured tripod-ball cage universal coupling drive shaft system applied to a small car are simulated and studied.The main research contents are as follows:（1）A micro-groove was designed on the surface of the sliding rod of the tripod universal coupling,and the unsteady hydrodynamic lubrication theoretical model of the sliding rod-sleeve hole contact pair was established,and the oil film thickness and oil film pressure on the textured surface are solved by numerical programming.Taking the friction coefficientμas the index,the influence of the mesh density of the control unit and the error limit in the overrelaxation iteration process on the calculation results is studied.Finally,the number of meshes in the control unit is 128×128,and the order of magnitude of the calculation error limit in the overrelaxation iteration process is 10^-5.（2）Based on the theoretical model of the second chapter,combined with the actual gear parameters of a small car,the unsteady hydrodynamic lubrication characteristics of the sliding rod-sleeve hole contact pair of the textured tripod universal coupling under different road conditions are studied.The results show that the appropriate increase of texture depth h_p,texture radius r_p and texture area ratio s_p is beneficial to the improvement of lubrication performance on the smooth road straight driving,from one to five gears.In the process of smooth road turning,the appropriate increase of texture depth h_p,texture radius r_p,texture area ratio s_p and texture depth to diameter ratio e is beneficial to the improvement of lubrication performance.In the process of bumpy road straight driving,an appropriate increase of texture depth h_p,texture radius r_p,texture area ratio s_p and texture depth to diameter ratio e can improve the lubrication state.In the process of turning on a bumpy road surface,increasing texture radius r_pand texture area ratio s_p is beneficial to lubrication.Under different road conditions,the influence of different parameters such as the viscosity of lubricating oilηand the radius of rotation R₀ of the sliding rod on the lubrication characteristics of the sliding rod-sleeve hole contact pair is also different.（3）A micro-groove was designed on the surface of the tripod of the tripod universal coupling.The unsteady hydrodynamic lubrication model of the joint bearing-tripod contact pair of the micro-groove textured tripod universal coupling was numerically solved.Combined with the actual gear parameters of a small car,the influence of working condition parameters and texture parameters on the hydrodynamic lubrication characteristics of the joint bearing-tripod contact pair under different road conditions was studied.The results show that the increase of texture depth h_p,texture radius r_p,texture area ratio s_p and texture depth-to-diameter ratio e will enhance the hydrodynamic pressure effect between the joint bearing-tripod contact pair to varying degrees in the process of smooth road straight driving,from one to five gears,which is beneficial to lubrication.The increase of the viscosity of the lubricating oilηand the radius of rotation of the sliding rod R₀ will increase the film thickness,but the friction f and the friction coefficientμwill show an upward trend,which is not conducive to lubrication.For the increase of the shaft angle?,the improvement of the lubrication performance is not great.In the process of smooth road turning and bumpy road straight driving and turning,the increase of texture depth h_p,texture radius r_p,texture area ratio s_p and texture depth to diameter ratio e is beneficial to the improvement of lubrication performance,while the viscosity of lubricating oilηand the radius of rotation of sliding rod R₀ needs to be selected according to the actual situation.（4）A micro-groove was designed on the inner surface of the bell-shaped shell of the ball cage universal coupling,and a steady-state hydrodynamic lubrication model of the bell-shaped shell-steel ball contact pair was established.Combined with the actual gear parameters of a small car,the effects of working condition parameters and texture parameters on the lubrication characteristics of the textured ball cage universal coupling under different road conditions were studied.The results show that the texture depth h_pshould not be too large in the process of smooth road straight driving,from one to five gears,otherwise it is easy to cause the hydrodynamic effect to weaken,which is not conducive to lubrication.The increase of texture radius r_p and texture area ratio s_p will increase the thickness of the lubricating oil film and reduce the friction between friction pairs,which is conducive to the improvement of lubrication performance.The increase of the radius of rotation R₀ of the slider will lead to a sharp increase in the entrainment speed of lubricating oil in the contact area,which will reduce the friction f and improve the lubrication performance.In the process of smooth road turning and bumpy road straight driving and turning,increasing the texture radius r_p,texture area ratio s_p and slide rod rotation radius R₀ is beneficial to the improvement of lubrication performance,while the texture depth h_p,texture depth ratio e and lubricating oil viscosityηare not conducive to the improvement of lubrication performance.（5）The transmission efficiency equation of the textured tripod-ball cage universal coupling drive shaft system is established,and it is numerically solved by MATLAB programming to study its transmission efficiency when applied to a small car.The results show that the average transmission efficiency of the transmission shaft system can be improved by increasing the rotary radius R₀ and texture radius r_p of the sliding rod and reducing the shaft angle?and the radius r of the three fork rod in the process of driving on a smooth road,from one to five gears,while the texture depth h_p needs to be reasonably selected according to the actual situation.In the process of smooth road turning and bumpy road straight driving and turning,increasing the rotary radius R₀ and texture radius r_p of the sliding rod and reducing the radius r of the trigeminal rod are beneficial to improve the average transmission efficiency of the transmission shaft system,while the texture depth h_p needs to be reasonably selected according to the actual situation.