Wind Turbine Rotor Blade Carrier Layout for Lower Pitch Bearing Loads
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Solution Overview
Problem
Large wind turbines face high bearing friction and costs due to the high loads on pitch bearings, which are exacerbated by the tilting moments caused by wind forces, and the complexity of rotor hub connections, limiting blade length and increasing production costs.
Innovation Solution
The rotor blade design features a carrier with a flange and a pitch bearing spaced towards the blade tip, reducing tilting moments by creating counteracting moments of area, allowing for smaller pitch bearings and drives, and increasing clearance between the rotor blades and the tower by angling the carrier axis relative to the pitch axis.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the pitch bearing is arranged directly at the blade root, then the connection structure is simplified, but the tilting moment on the pitch bearing increases significantly due to wind forces
Solution Approach 1:
The pitch bearing is relocated from the blade root (inner end) to an intermediate position along the blade span, changing the spatial dimension of the bearing's location. This dimensional change creates two opposing moments of area that partially compensate each other, reducing the net tilting moment on the pitch bearing while maintaining structural connection simplicity.
2Force
If larger pitch bearings are used to handle high tilting moments, then the bearing capacity is sufficient, but the bearing friction and required drive forces increase
Solution Approach 1:
The pitch bearing is positioned in advance at an optimized location along the blade span, before the blade root, where the geometry naturally creates counteracting moments. This preliminary positioning action reduces the tilting moment load on the bearing, allowing smaller bearing dimensions that generate less friction and require less drive force for pitch adjustment.
3Power
If the rotor blade length is increased to improve energy generation, then the power output increases, but the clearance between rotor blades and tower is reduced
Solution Approach 1:
The carrier axis is angled relative to the pitch axis, introducing a dimensional change in the blade's spatial orientation. This angular arrangement positions the blade tip further away from the tower in the horizontal direction, increasing the clearance between the rotating blades and the tower structure, thereby enabling longer blade lengths without compromising safety clearance.
4Manufacturing precision
If the rotor hub is precisely machined for accurate rotor blade fit, then the connection precision is improved, but the manufacturing complexity and costs increase
Solution Approach 1:
The rotor blade connection structure is segmented into a blade root portion and a separate carrier component. This segmentation allows the carrier to be designed and manufactured independently with optimized geometry, reducing the machining complexity requirements for the main rotor hub while maintaining precise connection through the modular interface between blade root and carrier.
Data Source
Figure 1
Figure 2a
Figure 2b
AI summary
The invention relates to a wind-turbine rotor blade (1, 1', 1"), comprising a blade root and a blade tip (5), a flange (7) arranged on the blade root side for fastening the rotor blade to a rotor hub of a wind turbine, and a pitch bearing (9b, 9a) for adjusting the angle of attack (β) of the rotor blade. According to the invention, the rotor blade has an unpitched carrier (11), on which the flange (7) is formed, wherein the pitch bearing (9b, 9a) is fastened to the carrier (11) and is spaced apart from the flange (7) toward the blade tip (5).