Floating Nut Retainer for Anti-Rotation and Tolerance Alignment
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Solution Overview
Problem
In aeronautical applications, particularly in aircraft engines, it is challenging to screw or unscrew a nut that is difficult to access and must remain stationary to prevent rotation during screwing, while also allowing for adjustment of dimensional tolerances and using standard threaded members.
Innovation Solution
A retaining device for a threaded member, which includes an intermediate element and a body that provide radial clearance, allowing the threaded member to self-position relative to the part during screwing, while preventing rotation using a coupling mechanism without radial or rotational play.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a nut is pre-fixed in the appropriate position to prevent rotation during screwing, then the threaded member can be prevented from turning, but the dimensional tolerances of the part cannot be adjusted
Solution Approach 1:
The device is divided into two functional segments: a first element (body) that prevents rotation of the threaded member, and a second element (intermediate element with radial clearance) that allows radial movement for tolerance adjustment. This segmentation resolves the contradiction by separating the anti-rotation function from the tolerance accommodation function.
Solution Approach 2:
The second element acts as an intermediary between the threaded member and the first element. It provides radial clearance that allows the threaded member to move radially for tolerance adjustment while still being prevented from rotating by the first element, thus mediating between the conflicting requirements of rotation prevention and tolerance adaptability.
2Adaptability or versatility
If a standard threaded member is used, then interchangeability and approval are improved, but special nuts are required to prevent rotation while allowing freedom of self-positioning
Solution Approach 1:
The anti-rotation function is extracted from the threaded member (nut) itself and transferred to the retaining device consisting of the first and second elements. This allows the use of standard threaded members without special features, as the rotation prevention is provided by the separate retaining device structure.
Solution Approach 2:
The retaining device acts as an intermediary mechanism that enables standard threaded members to function in applications requiring rotation prevention. Instead of modifying the standard nut, the intermediary retaining device provides the necessary anti-rotation capability while maintaining compatibility with standard threaded members.
3Ease of operation
If radial clearance is provided between the intermediate element and the body, then freedom of positioning is improved, but rotational play may increase
Solution Approach 1:
The device provides different quality characteristics in different locations: radial clearance is provided in the radial direction to allow positioning freedom, while the coupling between elements maintains substantial without-play characteristics in the rotational direction. This local differentiation of quality resolves the contradiction between positioning freedom and rotational precision.
Data Source
Figure 1~3
Figure 4~5
AI summary
A nut (2) is prevented from turning during screwing by a body (12) attached to one of the parts to be tightened (6) by rivets (14). The body (12) prevents the nut (19) from rotating via a ring (19) coupled without clearance with the nut (19) and coupled with radial clearance to the body (12), in order to allow the nut to self-position itself along the axis (3) imposed on the screw (4) by the bores (9, 11) traversed by the screw. The nut can thus be a standard nut or a floating cage nut. Application to the retaining of nuts that are inaccessible and/or require a high level of security against unintentional unscrewing.