High Ratio Gearbox with very low Bearing Loads: New single-stage planetary gear arrangement with stepped planets

摘要

This contribution introduces a gear-concept shown in Fig.1 with a planetary gear-set with stepped planets, within which the overlay of the forces in the planet gears results to very low bearing load on the planet bearings. Therefore this gearbox needs only a low number of bearings with very low loads. The gears in this gear concept have big helical angles and small tooth heights. In total that leads of a self-adjusting system with high efficiency. Preferably such a gearbox is suitable for the speed- and torque transmission between a rotor of a wind turbine and a medium-fast operating generator. Even with medium-fast operating generators gearboxes in wind turbines need ratios of i_(total)=30...40 between generator and rotor. According to the state of the art the input sided slow running gear sets in "wind gearboxes" are designed as planetary gear sets. There the big torques lead to big tooth forces. In simple planetary gear sets with three shafts at sun, ring and carrier and negative stationary ratios this leads to very big loads on the planet-bearings. Then especially at low loads in such bearings roller slip and cage slip can happen. In fact bearing damages caused by such slip effects have already been reported several times. The concept of the "balanced" gear presented in this paper avoids these disadvantages.