Analisi del load sharing factor in rotismi epicicloidali = Load Sharing Factor analysis for epicyclic drivetrains

“A gear train is a mechanical system formed by mounting gears on a frame, so the teeth of the gears engage. Gear teeth are designed to ensure the pitch circles of engaging gears roll on each other without slipping, providing a smooth transmission of rotation from one gear to the next”. [1] “An epicyclic gear train (also known as a planetary gearset) consists of two gears mounted so that the center of one gear revolves around the center of the other. A carrier connects the centers of the two gears and rotates the planet and sun gears mesh so that their pitch circles roll without slip. An epicyclic gear train can be assembled so the planet gear rolls on the inside of the pitch circle of a fixed, outer gear ring, or ring gear”. [2] In the automotive field, epicyclic geartrains are adopted for the final drive of the half-axes (front and rear) to avoid tire slippage over the ground surface during cornering. They are mounted in between the half-axes, and their presence allows the transmission of torque from the drivetrain to the wheels. The torque can be evenly split or not, depending on the driving conditions. In the same way, wheel speeds can be differentiated to avoid tire slippage. Since the torque applied by the drivetrain on the epicyclic gearset can be quite high, matching gear teeth must undergo minimum deformations to ensure the proper working of the system. In this project, an investigation on the Load Sharing Factor has been carried out, both for the Sun-Planet and Planet-Ring matching, for different load conditions. The analysis was performed with the help of MatLab® software, from which both numerical and graphical data were retrieved. A dedicated part of the script was developed to achieve these results. The code concerns the writing of the stiffness matrix of the entire epicyclic drivetrain as function of the meshing positions during the contact phase. The evaluation of the Load Sharing Factor becomes possible by analysing the differences in input and output torques applied to the gearset, which are due to the contact teeth deformations.