Load sharing and distributed on the gear flank of wind turbine planetary gearbox

In the design of wind turbine gearboxes, the most important objective is to improve the durability to guarantee a service life of more than 20 years. Planetary gearsets, commonly used in wind turbine gearboxes, should have good load distribution and load sharing among gears to improve the durability. This work investigates how the optimal helix modification influence both the load distribution over the gear tooth flank and the planet load sharing. A whole system model is developed to analyze a wind turbine gearbox (WTG) that consists of planetary gearsets. The model includes the nonlinear mesh stiffness of gears and the nonlinear stiffness of bearings as well as the flexibilities of the housing, planet carriers, and ring gears. The results presented state that if the optimal helix modification is applied, the edge loading of gear tooth ends will disappear and the contact pattern will improve significantly. This is why the face load factor will decrease and the gear safety factor will increase. However, the mesh load factor is decreased slightly after helix modification. This means that the helix modification is not directly related to the mesh load factor.