Self-Tensioning Fastener Assembly for Stable Wind Turbine Preload
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Solution Overview
Problem
Mechanical fasteners used for tension connections, such as bolts or nuts, are prone to failure due to external loads and require regular maintenance, and existing tensioners are insensitive to external influences like weather, leading to inconsistent preload and potential self-loosening.
Innovation Solution
A fastener apparatus with a flange, lifting elements, and spacers that create a gap between the flange and support member, where spacers maintain tension forces after lifting elements are removed, providing a stable and maintenance-free connection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If mechanical tensioners are used to maximize preload on the fastener, then the target preload can be achieved, but the installation is prone to failures due to technician boredom or mistake and is susceptible not to assure accomplishment of target preload
Solution Approach 1:
The fastener system performs its own tensioning operation through the jack bolts that are integrated into the fastener structure. The jack bolts automatically apply the necessary preload when tightened, eliminating the need for external mechanical tensioners and technician intervention. This self-service mechanism ensures consistent preload application without human error.
Solution Approach 2:
The fastener is divided into functional segments including the main fastener body and separate jack bolts. The jack bolts are threadedly engaged with holes in the flange and can be independently torqued to apply precise compressive reaction forces on the support member, enabling controlled preload application without external equipment.
2Reliability
If external mechanical tensioners are used to provide preload, then tension connection can be established, but the tensioners are extremely insensitive to external loading and need to be maintained and inspected on a regular basis due to weather influences
Solution Approach 1:
The external mechanical tensioners are completely removed from the system. Instead, the preload function is integrated directly into the fastener structure through jack bolts that are threadedly engaged with the flange. This extraction of external components eliminates maintenance requirements while maintaining connection stability.
Solution Approach 2:
The jack bolts serve as intermediary elements that transfer the tightening force from the fastener to the support member. These jack bolts are protected within the flange structure, shielding them from weather influences while maintaining their load-bearing function, thus eliminating maintenance needs.
3Strength
If larger fasteners are used to provide stable tension connection, then connection strength is improved, but the weight and size of wind turbine components increase
Solution Approach 1:
The fastener system applies localized compressive forces through the jack bolts at specific points on the support member. This concentrated local action creates high compression forces in targeted areas, providing stable tension connection without requiring the fastener itself to be oversized or heavily weighted.
Solution Approach 2:
The jack bolts are pre-positioned within the flange structure and are ready to apply compressive forces immediately upon tightening. This preliminary arrangement of the tensioning mechanism within the fastener itself eliminates the need for additional weight in external tensioning devices, achieving strong connections with lighter overall fastener design.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The apparatus ensures a stable and reliable tension connection that is insensitive to external influences, reduces the need for maintenance, and allows for smaller, lighter wind turbine designs by minimizing external loads and self-loosening dynamics.
Implementation Method 1
Each lifting element is configured to engage in a hole of the plurality of holes, to extend from the holes and to abut against the support member under an applied torque in order to tension the fastener
Implementation Method 2
each spacer is configured to engage into the gap between the support member and the flange, such that tension forces applied on the fastener are maintained after the plurality of lifting elements are removed from the fastener
Data Source
Figure 1~2
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AI summary
The invention described herein relates to an apparatus (100) for providing a secure tension connection, the apparatus (100) comprising a fastener (101) with a flange (103) for interaction with a shank (105), a plurality of lifting elements (107, 109, 125, 127), and a plurality of spacers (111, 113). The invention further relates to a wind turbine (400) with such an apparatus (100), a tool (200) for securing an apparatus (100) and a method (300) for providing a secure tension connection.