| The compound planetary gearbox/reducer is a key component of the automotive transmission system,whose stability and reliability directly determine the driving quality and driving feeling.The compound planetary gear transmission system has the advantages of small size,high transmission ratio and good power splitting,and has been gradually applied to transportation fields such as vehicles,aviation and ships.Although the advantages of compound planetary gearbox/reducer are outstanding,contact characteristics and dynamic characteristics are susceptible to influence by various internal and external excitations(such as transmission error,tooth alignment error,load and speed)due to so many components of itself,which may result in degradation of its characteristics.In this thesis,the influence of meshing misalignment on the contact characteristics and dynamic characteristics of the compound planetary gear transmission is analyzed for the tooth misalignment,caused by the manufacturing and installation errors,during the gear meshing.The influence of meshing misalignment on the meshing stiffness,contact impression,transmission error and dynamic behavior of the transmission system is studied.The contact behavior and dynamic behavior of the compound planetary gear train with meshing misalignment were verified by single tooth torque test,contact print test,transmission error test and virtual prototype in ADAMS environment.The main research contents and results of the thesis are as follows:1.The influencing factors and influence mechanism of meshing misalignment are analyzed.According to the influence mechanism of different influencing factors,1)The mathematical relationship between error and misalignment under the condition that the shafting is not parallel and the shafting is staggered is established;2)The influence of the coaxiality deviation of the bearing hole on the misalignment of the mesh is analyzed,and the mathematical relationship between the two is established;3)The influence of bearing radial clearance on meshing misalignment is analyzed and the mathematical relationship between them is established;4)The influence of the bending and torsional deformation of the gear shaft on the meshing misalignment is analyzed,the mathematical relationship between the misalignment and the shafting load and structural parameters is established.Based on the influence mechanism and mathematical relationship,the guidelines of gearbox shaft structure design are obtained.2.In order to analyze the influence of meshing misalignment on gear meshing stiffness,contact impression and transmission error,a "waist drum" contact model is established for involute cylindrical gears.It is proposed that the misaligned waist drum model only affects the position of the contact center and does not affect the co ntact stress distribution regulation.Based on the assumption,the relationship between contact deformation/stress variation coefficient and misalignment is derived.It is agreed that based on this assumption,the bending and torsion model of the tooth und er the misalignment condition is proposed,where a simplified functional relationship between bending deformation and misalignment,and a simplified functional relationship between shear deformation and the misalignment are derived based on this model.3.Taking the meshing misalignment into consideration,the "translation-torsion" dynamic model of the compound planetary gear transmission system is established based on the centralized parameter method and the Lagrange equation,combined with the mathematical relationship between the clearance and the meshing misalignment.Comparing the changes of steady-state dynamics of the system before and after the meshing misalignment,the influence of meshing misalignment on the dynamic characteristics of compound planetary gearbox is analyzed based on the nonlinear dynamics theory of gear clearance.4.Based on the harmonic balance method,the influence of the variation of the meshing misalignment on the "vibration-shock" characteristics of the compound planetary transmission system is analyzed.Based on the bifurcation diagram,the phase-track line and the Poincaré section,the influence of the variation of the meshing misalignment on the periodic motion characteristics of the compound planetary transmission system is analyzed;the influence of the variation of the meshing misalignment on the shunt characteristics of the system load is analyzed.5.Through the single tooth pair static torque test,gear pair contact print test and transmission error test,the influence of mesh misalignment on meshing stiffness,contact characteristics and transmission accuracy is verified in Chapter 3.The test shows that: 1)The meshing misalignment will cause the equivalent meshing rigidity of the gear pair to decrease.In the elastic range,the stiffness decreases with the increase of the meshing misalignment,which is an approximate parabolic trend;2)The meshing misalignment causes a single-sided contact of the gear pair.As the amount of misalignment increases,the contact zone gradually moves toward one end,and the contact rate decreases;3)The peak-to-peak value and effective value of the transmission error increase with the meshing misalignment,and the internal excitation of the gear system is enhanced.6.The virtual prototype model was built in the ADAMS environment to verify the load sharing characteristics of the compound planetary gear train with meshing misalignment.The working conditions and problems of the target gear pair are analyzed,and the equivalent clearance amount introduced by the meshing misalignment is input.The meshing behavior of meshing pair was restored by ADAMS modeling.The influence of the meshing misalignment on the dynamic meshing force and the load sharing characteristics was analyzed.The calculated results were compared with the theoretical results to demonstrate the correctness of the theoretical analysis. |
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