Planetary Bearing Design (Plabed)
To meet the rising demands regarding reliability and profitability of wind turbine generators, optimal loadcapable design of all components is required. In order to do so, the applied loads as well as the load limits of all components need to be known. The failure of the gearbox of a wind turbine generator usually leads to a long downtime and also to expensive repair measures. About two-thirds of those failures are caused by bearing damages. Within the gearbox, the bearings carrying the individual planet gears are some of the most heavily stressed parts. Assembly situation and design of the bearing, elasticities of adjacent components and meshing forces of the planet gear are relevant parameters influencing the load distribution within the bearing of the planetary gear. Under load these parameters lead to displacements within the gearbox such as misalignments of the sun gear, planetary gears and ring gear as well as axial and tangential movement of bearing rings all of which can have negative influence on the local load distribution within the bearing. Typical consequences are bearing fatigue and smearing. Additionally, if ring movement occurs, fractures of the bearing ribs, wear at the bearing seats, or damage at the circlips can be found. Due to uncertainties in the calculation concerning both, the input loads of the gearbox as well as the calculation of bearing loads and deformations, the damages stated above cannot be completely ruled out in today’s design process. The goal of this project therefore is to extend the current calculation models so that all relevant parameters influencing the load distribution in the planetary bearings can be considered appropriately. In order to quantify the individual parameter’s influences, a bracing rig will be designed and built in the project which can actively apply the complex loading and deformation situations that occur in a gearbox. From this, knowledge on the complex interrelationships within the system planetary bearing will be obtained and used to formulate an extended design guideline for planetary bearings in wind turbine generators.
Novel planetary bearing test methods