Application of flexible pin for planetary gear set of wind turbine gearbox

Ho-Gil Yoo,Young-Jun Park,Beom-Soo Kim,Woo-Jin Chung,Su-Chul Kim,Geun-Ho Lee

doi:10.1038/s41598-022-05828-1

Ho-Gil Yoo, Young-Jun Park + Show 4 more

Open Access

https://doi.org/10.1038/s41598-022-05828-1

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Abstract

Wind turbines are eco-friendly energy sources that generate electricity from wind power. Among their various components, gearboxes constitute the most critical loss owing to their longest downtime. To guarantee their durability, a flexible pin was designed based on the original straddle-mounted pin for enhanced tooth load sharing and distribution in the planetary gear set (PGS) of a wind turbine gearbox (WTGB). The improved durability was evaluated by calculating the mesh load factor and face load factor for contact stress and comparing these values with those of the original straddle-mounted pin. The mesh load factor decreased from 1.37 to 1.08, whereas the maximum face load factor decreased slightly, moderating the overall safety factor variation. Furthermore, the structure of the proposed flexible pin model was analyzed and verified that no static failure or interference occurred. Additionally, microgeometry optimization was applied to improve the load distribution. Therefore, it was verified that a flexible pin applied to a single helical-geared PGS, thus far considered impossible, enhances the durability of WTGBs by improving the load sharing and distribution of a PGS. Consequently, the possibility of designing single helical-geared planetary gearboxes with flexible pins to take advantages of both helical gears and flexible pins was shown analytically.

Highlights

Increasing the number of planet gears effectively increases the power density of a planetary gear set (PGS)
Montestruc designed a tapered flexible pin model and compared the finite element analysis (FEA) results with those reported by Hicks and Fox and Jallat, emphasizing that the maximum stress and load sharing performance vary with the pin g eometry[22]
Fox and Jallat reported that applying a flexible pin to a single helical-geared PGS can deteriorate the load distribution on the tooth surface owing to the axial component of the gear mesh force causing tilting moments and gear body m isalignment[21]

Summary

Introduction

Increasing the number of planet gears effectively increases the power density of a PGS. 40 years later, Fox and Jallat patented a revised flexible pin model exhibiting a better load sharing performance than that of Hicks, under high loads due to the self-aligning effect They reported that spur gears are preferred over helical gears in designing flexible pins because even a small helix angle can generate thrust forces causing overturning moments, which may not achieve optimal c ompliance[20,21]. Existing studies primarily focused on flexible pins in the design stage as they improve the load sharing performance of PGSs. Fox and Jallat reported that applying a flexible pin to a single helical-geared PGS can deteriorate the load distribution on the tooth surface owing to the axial component of the gear mesh force causing tilting moments and gear body m isalignment[21]. Thereby, the advantages of both helical gears and flexible pins could be exploited and the applicability of the proposed flexible pin was demonstrated to a single helical-geared PGS

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