Flexible Coupling for Wind Turbine Misalignment
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Solution Overview
Problem
Wind turbine power transmission systems face challenges with gearbox and bearing reliability due to unpredictable parasitic forces from varying loads, machine tolerances, and thermal expansions, which can lead to component damage, particularly in geared and direct-drive systems.
Innovation Solution
A power transmission system with a main shaft and gearbox design that includes a flexible coupling between the main shaft and gearbox input member, allowing translational and rotational degrees of freedom to accommodate misalignments and distribute forces, while the gearbox housing is suspended from the support structure, eliminating direct load paths to the tower.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a gearbox is used to increase rotational speed from rotor to generator, then the generator can operate at higher speed with smaller size, but parasitic forces from load variations and misalignments damage gearbox components and bearings
Solution Approach 1:
A flexible coupling element is introduced as an intermediary between the main shaft and gearbox input member. This coupling element absorbs misalignments and reduces parasitic forces through its flexibility, protecting the gearbox and bearings while maintaining power transmission functionality.
Solution Approach 2:
The patent changes the mechanical parameters of the connection between main shaft and gearbox by introducing degrees of freedom (translational and rotational) that allow the system to adapt to load variations and thermal expansions, reducing stress on critical components.
2Reliability
If direct-drive system is used without gear stage, then gearbox concerns are reduced, but main bearing and generator components suffer from parasitic loads and generator size increases
Solution Approach 1:
The flexible coupling serves as a mediator that protects generator components from parasitic loads without requiring a gear stage, enabling the use of smaller high-speed generators while maintaining reliability.
3Manufacturing precision
If rigid coupling is used between main shaft and gearbox input member, then alignment precision is maintained, but sensitivity to alignment mistakes and tolerances increases leading to parasitic forces
Solution Approach 1:
The coupling design changes from rigid to flexible by introducing translational and rotational degrees of freedom, allowing the system to tolerate manufacturing imperfections and operational misalignments without generating harmful parasitic forces.
4Stability of the object's composition
If gearbox housing is rigidly coupled to support structure, then structural stability is maintained, but load path through gearbox housing to tower increases complexity and potential damage points
Solution Approach 1:
The patent segments the load path by suspending the gearbox housing from the support structure rather than rigidly coupling it, creating a separate suspension system that simplifies the overall load path while maintaining structural stability.
Data Source
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AI summary
A flexible coupling for use in a wind turbine power transmission system to flexibly couple terminal portions of the wind turbine power transmission system to thereby accommodate misalignments in a radial and axial direction between the terminal portions. A coupling element of the flexible coupling interfaces with the terminal portions associated with a main shaft and a gearbox input member of the wind turbine power transmission system. Thereby a double-joint, namely two joints between the coupling element and the respective terminal portions, is defined. The joints permit relative rotation between the coupling element and the respective terminal portion around axes perpendicular to and relative translation along a main axis of the main shaft. Thereby the two joints can provide translational degrees of freedom in all directions and rotational degrees of freedom only about axes perpendicular to the main axis to accommodate radial, axial, and angular misalignments. A torsionally stiff coupling element may constrain relative rotation about the main axis.