Elliptical Braking Nut Structure for Multi-Cycle Torque Retention
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Solution Overview
Problem
Existing braking nuts for aeronautical fasteners face challenges in maintaining sufficient braking torque after multiple mounting and dismounting cycles, often requiring increased height or reduced key grip height, which can result in insufficient tightening torque.
Innovation Solution
A braking nut design featuring an elliptical braking skirt with a larger perimeter lower zone and a hexagonal upper zone, including through holes between first flats, allows for efficient torque transmission and flexible braking without increasing the nut's overall height, incorporating an enlarged base and specific flat configurations for enhanced torque application.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a cylindrical braking skirt is provided to maintain braking torque after multiple mounting/dismounting cycles, then braking reliability is improved, but the nut height increases or key grip height is reduced
Solution Approach 1:
The braking skirt is designed with an elliptical cross-section instead of a cylindrical shape, creating asymmetry that allows the skirt to deform and conform to the support surface more effectively. This asymmetric geometry enables the braking function to be achieved with a shorter nut height, as the elliptical shape provides better contact and friction engagement with the support surface during mounting and dismounting cycles.
2Reliability
If the key grip height is reduced to accommodate a braking skirt, then braking function is improved, but tightening torque transmission is compromised
Solution Approach 1:
The elliptical braking skirt creates an asymmetric geometry that allows the driving surface to maintain sufficient height for torque transmission. The asymmetry of the elliptical shape enables the braking skirt to be positioned such that it does not encroach on the key grip height, thereby preserving the force transmission capability while still providing effective braking function.
Solution Approach 2:
The braking function is achieved by utilizing the elliptical cross-sectional dimension rather than increasing the axial height. By changing from a cylindrical to an elliptical shape, the braking skirt engages the support surface through its width rather than its height, allowing the nut to maintain adequate key grip height for torque transmission while still providing effective braking through the elliptical geometry.
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
This design maintains effective braking torque through multiple cycles while minimizing the nut's height and allowing for efficient wire brake integration, ensuring secure locking without compromising the nut's structural integrity.
Implementation Method 1
The skirt is more flexible than the body of the nut and deforms elastically some times, unlike the body of the nut which is relatively more rigid.
Data Source
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AI summary
The present invention relates to a locking nut (10) comprising: a body (20) and a bore through said body along a principal axis, the body comprising: a bearing face (30); a drive surface (32); and at least one through hole (38), substantially perpendicular to the principal axis from the radial drive surface. The body further comprises an elliptical braking skirt (36); and the drive surface comprises an upper zone (50) and a lower zone (52), adjacent along the principal axis, the lower zone being located between the upper zone and the bearing surface; a perimeter of the lower zone around the principal axis being greater than a perimeter of the upper zone; the at least one through hole (38) extending from the upper zone (50).