Research On Gear Profile Modification Based On Stiffness Of Elastohydrodynamic Friction Pairs

For high-speed high-power transmission gear used in high-speed railway,ship,helicopter,megawatt wind turbine and other occasions,as well as for automobile and other transmission gear with high comfort requirements,modification has become an essential part of the gear design process.Proper gear modification can not only greatly reduce or even avoid the dynamic load,reduce the vibration and noise in the process of gear meshing,but also greatly improve the transmission accuracy and strength of gear.Used for high-speed trains,ships,helicopters,megawatt wind turbines,high-end gear such as cars,usually work in elastohydrodynamic lubrication state,elastohydrodynamic lubrication of the gear is closely related to modification of mutual influence and role,however,so far,about the gear modification and the modification gear elastohydrodynamic lubrication analysis is carried out respectively,when the gear modification has never considered the effect of lubrication.In this paper,the relationship between gear modification and elastohydrodynamic lubrication is established for the first time,and a new method of gear modification using the meshing stiffness of elastohydrodynamic friction pairs instead of the traditional gear meshing stiffness is proposed.The thesis mainly does the following work:(1)Based on the theory of elastohydrodynamic lubrication,the elastohydrodynamic oil film was simplified into linear spring damping,and the tribology-dynamics coupling model of linear contact friction pair was established.The stiffness of tooth surface elastohydrodynamic friction pair was obtained by numerical method.(2)The meshing stiffness definition of ISO gear was adopted to calculate the meshing stiffness of gear elastoflow friction pair,and the maximum modification amount was calculated based on the meshing stiffness of gear elastoflow friction pair to modify the gear shape.(3)The meshing models of standard gear,ISO gear and elasto-flow friction pair were established by Creo respectively.The dynamic meshing force,angular acceleration and transmission error of the three gear pairs were simulated and compared by Adams and Romax.The results show that the gear stiffness decreases obviously after considering the influence of elastohydrodynamic lubrication,leading to the increase of the maximum modification amount of gear,and the modification effect based on elastohydrodynamic friction pair stiffness is better than that of ISO method,and the gear dynamic performance and transmission performance are significantly improved.(4)Elastohydrodynamic lubrication of gears modified based on meshing stiffness of elastohydrodynamic friction pairs is compared with that modified based on ISO method.The results show that gear modification based on meshing stiffness of elastohydrodynamic friction pairs can further improve gear lubrication.