Wind Turbine Gearbox Coupling for Parasitic Load Isolation
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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 variable loads, machine tolerances, and thermal expansions, which can damage components, and direct-drive systems face issues with larger generators and rare earth material limitations.
Innovation Solution
A power transmission system with a flexible coupling between the main shaft and gearbox input member, allowing translational and rotational degrees of freedom, and a suspended gearbox housing to distribute forces, reducing sensitivity to alignment mistakes and load deformations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If a gearbox is used to increase rotational speed, then the generator can operate at higher speed with smaller size, but the reliability of gearbox components deteriorates due to parasitic forces from load deformations, thermal expansions, and tolerance variations
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 parasitic forces that would otherwise be transmitted to the gearbox components, protecting them from damage while allowing the gearbox to function effectively.
Solution Approach 2:
The system allows for changes in relative position and orientation parameters between the main shaft and gearbox input member through the flexible coupling. The coupling element can accommodate radial, axial, and angular misalignments, enabling the system to adapt to thermal expansions, load deformations, and tolerance variations without compromising reliability.
2Device complexity
If direct-drive system is used to eliminate gearbox, then component count is reduced, but main bearing reliability deteriorates due to parasitic loads and generator size increases requiring rare earth materials
Solution Approach 1:
The flexible coupling serves as a mediator that protects the main shaft and bearings from parasitic loads even in direct-drive configurations. By absorbing misalignments and isolating the bearing system from harmful forces, the coupling maintains bearing reliability while allowing the simplified direct-drive architecture.
Solution Approach 2:
The flexible coupling extracts and isolates the parasitic load paths from the main bearing system. By taking out the harmful force transmission path through the coupling element, the main bearings are protected from damages that would otherwise require oversized generators and rare earth materials.
3Manufacturing precision
If rigid coupling is used between main shaft and gearbox input member, then alignment precision is improved, but sensitivity to tolerance variations and thermal expansions worsens causing parasitic forces
Solution Approach 1:
The flexible coupling enables parameter changes in relative position and orientation between the main shaft and gearbox input member. It accommodates radial, axial, and angular misalignments, allowing the system to adapt to tolerance variations and thermal expansions without generating harmful parasitic forces.
Solution Approach 2:
The coupling element provides dynamic adaptability between the main shaft and gearbox input member. Rather than maintaining a fixed rigid connection, the flexible coupling allows real-time adjustment to misalignments caused by thermal expansions, load deformations, and manufacturing tolerances, preventing the generation of parasitic forces.
Data Source
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AI summary
A power transmission system for increasing the rotational speed from a rotor of a wind turbine comprises a main shaft configured to be driven by the rotor, a support structure, and a gearbox. The support structure includes at least one bearing supporting the main shaft for rotation about the main axis, with no other degrees of freedom between the main shaft and support structure. The gearbox includes a gearbox housing rigidly coupled to the support structure and a gearbox input member coupled to the main shaft. The gearbox housing supports the gearbox input member for rotation about the main axis without any other degrees of freedom, and the gearbox input member is coupled to the main shaft with translational degrees of freedom in all directions and rotational degrees of freedom about axes perpendicular to the main axis. This coupling comprises a main-shaft terminal portion, an input-member terminal portion, and a coupling element, together defining two joints.