Study of Shrink Disc for 5 MW Class Offshore Wind Turbine

摘要

A shrink disc is a shaft coupling device that connects the rotor shaft and an input shaft of a speed-increasing gearbox of a wind turbine. The shrink disc connects the two shafts using the coupling friction force between a tapered external sleeve and an internal sleeve. In the present study, a structural analysis was performed to investigate the shape design of a single type shrink disk for a 5 MW class offshore wind turbine. The shrink disk was used to connect the main shaft and the input shaft of a speed-increasing gearbox. In addition, to precisely estimate the vertical force applied by the bolt axial force, an experiment was performed to calculate the torque coefficient, which represents the relationship between the axial force and the clamping force of the bolts that generate the vertical force between a friction plate and a steel plate. The experiment showed that the torque coefficient was 0.17. Considering the maximum transmissible torque and the yield strength of the material, the optimal draft angle of the single type shrink disc for a 5 MW class offshore wind turbine was 2°. In addition, a structural analysis conducted with various numbers of clamped bolts showed that the valid minimum number of bolts was 32. The analysis of the fatigue lifetime of the shrink disc showed that safety was secure for at least 20 years.