Application of structural topology optimisation for planetary carrier design

A planetary gear train is very common in automatic gearboxes nowadays as well as in manual gearboxes for a low range or reduces. The main advantage of this gear train is compactness with a connection to a high possible gear ratio. Additional advantages such as a possibility to change of the gear ration and direction of rotation with a straightforward method by stopping one of three main components of the gear train can be found. Of course, the planetary gear train has disadvantages like a complex design that requires precise gears and a planet carrier with high torsional stiffness.
The presented work concerns an essential part of the planetary gear train, namely, design of the planet carrier. An application of heavy-duty commercial gearboxes is selected because large torque levels dominate in this application and then the design of the carrier is crucial. One of the most important parameters of the plant carrier is its torsional stiffness, which has a direct influence on stress level gears. The low stiffness leads to uneven contact between the gears during loading, which reduces pitting resistance of the gears. The next important parameter is the stress level in the planet carrier, because of varying torque the planet carrier is exposed to fatigue failure. These two parameters are taken in the design process as the main factors.