| The research subject of the dissertation stems from some type transfer case product development, the supporting projects of a high-power automatic transmission, aiming at independently developing design of a high-power automatic transmission transfer case.The transfer case is an important part of automatic transmission,which is the transmission equipment making a role in distributing automatic transmission output power to each drive axle, decelerating and increasing torsion. Also, it is a key component for the multi-axis driving transmission system, its quality and performance directly affect the transmission and dynamic performance of automatic transmission. It is a heavy load gear transmission equipment with high torque load under working condition of complex mechanical properties, is one of the weaknesses for the multi-axis driving transmission system. Currently, in terms of design and manufacturing technology of high-power transfer case, most of the domestic manufacturers is still at the stage absorbing the foreign design technology, result in the domestic high-power transfer case has high failure rate. Therefore, gear meshing characteristic analysis and gear Modification of Transfer Case, which will improving the capacity of independent design and development for high-power transfer case and reducing the failure rate, plays an important role to promote localization of high-power transfer case.The main contents of this dissertation are shown as follows:①The main structure forms and transmission characteristics and transmission principles of transfer cases are introduced. The development tendency and present situation of research on transfer cases at home and abroad are reviewed. A 3D model(2 grade parallel axle + a planetary gear train) studied in this paper is established by using Romax, and virtual assembly and interference checking are done.②The basic principle of gear tooth profile modification and lead modification are introduced, the gear modification model is modeling based on transfer case 3D model, considering the gear meshing system comprehensive deformation, using addendum long curve tooth profile modification and the helix angle with drum shape and end relief lead modification, and analyses the influence of modification parameters on gear meshing characteristics.③The transfer case modification gears meshing model in condition of error and load coupling are established with use of the finite element method, and load tooth contact analysis is done. The effect of installation’s and manufacture’s error and external load are researched on gear bearing tooth contact dot, flash temperature distribution on tooth lead and profile, transmission error and mesh misalignment etc, and evaluate parameters’ sensitivity. The transfer case gears composite modification parameters are optimized based on LTCA, the gears meshing performance are comparative analysed before and after modification.④ The transfer case performance is comparative analysed before and after modification. The strength of key components of the transfer case are analysed in the extreme conditions, obtaining the housing stress and deformation nephogram, bearing and gear static strength respectively; Gears contact fatigue strength, bending fatigue strength and bearings fatigue life in transmission system are checked in the rated condition, verifying the correctness of composite modification parameters. |
