Anti-rotation Device for Large Nuts Using Overlapping Notches
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Solution Overview
Problem
Existing anti-rotation devices for large diameter nuts, such as those used in aircraft engines, are inadequate as they require internal components like ventilation tubes or fingers, which are not present in all male parts, limiting their applicability.
Innovation Solution
An anti-rotation device featuring a ring with a long finger housed in overlapping notches on both the nut and the male part, along with optional short fingers for balancing, allowing for stable positioning without internal components, optimizing the alignment and torque reduction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a self-locking device is used for nut anti-rotation, then the anti-rotation function is achieved, but the device is only suitable for small size nuts (4 to 15.875 millimeters in diameter)
Solution Approach 1:
The anti-rotation device is segmented into multiple independent components: a ring with multiple fingers (at least three fingers spaced around the circumference), each finger capable of independently engaging with corresponding notches on the male part. This segmentation allows the device to accommodate large diameter nuts by distributing the anti-rotation function across multiple points rather than relying on a single self-locking mechanism
Solution Approach 2:
The ring structure with multiple fingers serves multiple functions simultaneously: it provides anti-rotation capability, balances radial forces through symmetric finger distribution, and adapts to various male part geometries by having fingers that can engage with notches at different positions. This multi-functional design makes the device universally applicable to both small and large diameter nuts, as well as different male part configurations
2Reliability
If a finger is installed on a ventilation tube inside the turbine shaft, then the anti-rotation function is ensured, but the solution is not applicable when no internal part is present in the male part
Solution Approach 1:
The anti-rotation device is extracted from the internal configuration (finger on ventilation tube inside shaft) and repositioned to an external configuration where the ring with fingers engages directly with notches on the male part surface. This extraction eliminates the dependency on internal male part structures, allowing the device to function reliably whether or not ventilation tubes or other internal components are present
Solution Approach 2:
The ring acts as an intermediary element that mediates between the nut and the male part. Instead of requiring a direct connection between a finger and an internal male part structure, the ring with its multiple fingers serves as a mediator that can engage with notches on the male part surface, providing anti-rotation functionality without needing internal male part structures
3Stability of the object's composition
If multiple notches are created on the nut and male part, then the anti-rotation device can be optimized for stability and torque distribution, but the manufacturing complexity increases
Solution Approach 1:
The device utilizes asymmetric notch positioning on the male part combined with corresponding asymmetric finger arrangement on the ring. This asymmetric configuration optimizes the engagement geometry for stable anti-rotation while allowing the notches to be manufactured using standard machining operations. The asymmetry ensures proper force distribution and prevents premature disengagement without requiring complex manufacturing processes
Data Source
Figure 1~3
AI summary
The invention concerns an anti-rotation device (10) for a nut (11) in tightened position on a male part (12), said device (10) being characterised in that it comprises: ° a plurality of upper notches (13) provided on one end of the nut (11), said upper notches (13) extending along a longitudinal axis of the nut (11), ° a plurality of lower notches (14) provided in one peripheral zone (15) of the male part (12), said lower notches (14) extending along a longitudinal axis (X) of the male part (12), and said lower (14) and higher (13) notches at least partially overlapping when the nut (11) is in tightened position on the male part (12), ° a ring (16) comprising at least one locking means (17) accommodated both in one of the lower notches (14) of the male part (12) and in one of the higher notches (13) of the nut (11).