Contact Fatigue Life of Yaw Drive Pinion Using e-PGS

The yawing system is a core component of a wind power generator and is driven by engaging several yaw reducers and a ring gear present on the outer periphery of the yaw bearing. However, the global competitiveness of domestic industries ranging from design to manufacture is poor with respect to MW-class large ring gears. To solve this problem, an external pinwheel gear set (e-PGS) system is introduced in this study as an alternative to the conventional yawing system. To obtain higher contact fatigue resistance in the pinion, we adopted a profile-shifted tooth profile. The contact forces were then determined and the Hertz contact stresses were investigated to estimate the surface fatigue life by varying the shape design parameters. Results of our proposed e-PGS system demonstrate that the fatigue design life of a yaw drive pinion can be extended significantly by increasing the profile shift coefficient. More specifically, we determined that an appropriate lifespan can be obtained only when this coefficient reaches or exceeds a certain level.