Shut-off Plug with Automatic Locking for Vibration
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Solution Overview
Problem
Aircraft engine maintenance requires a stopper device that prevents untimely unscrewing due to vibrations, while existing solutions complicate manufacturing, assembly, and accessibility in cramped engine spaces.
Innovation Solution
A closure device with a plug featuring a central body and locking/unlocking means, where the cap has a skirt linked to the central body with guide means allowing radial movement, and a spring for elastic return, ensuring automatic locking against vibrations without requiring specific machining or tools.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If additional locking parts (locking washer, locking pin, or wire) are placed on the plug to prevent loosening, then the reliability against spontaneous unscrewing is improved, but the device complexity and difficulty of installation increase due to poor accessibility in engine spaces
Solution Approach 1:
The locking means are integrated directly into the plug structure, merging the locking function with the plug body. The plug includes a crown with teeth that engage with a fixed crown on the housing, eliminating the need for separate locking washers, pins, or wires. This integration reduces device complexity while maintaining reliability against vibration-induced loosening.
Solution Approach 2:
The locking system is automatically activated by the rotation and axial progression of the plug during screwing. The helical compression spring automatically pushes the crown teeth into engagement with the fixed crown, requiring no manual intervention or special tools for activation. The system serves itself by utilizing the screwing motion to trigger the locking mechanism.
2Reliability
If a crown with keys or flats is integrated into the plug to achieve rotary coupling, then the locking function is improved, but the manufacturing complexity increases due to specific machining requirements that can weaken the central body
Solution Approach 1:
The rotary coupling features (keys or flats) are extracted from the central body and transferred to the crown itself. The crown is given a non-circular periphery that directly engages with a corresponding feature on the housing, eliminating the need to machine keys or flats into the central body. This preserves the structural integrity of the plug while achieving the desired rotary coupling.
Solution Approach 2:
Instead of creating rotary coupling features on the central body and having the crown engage them, the invention inverts the approach by placing the coupling features on the crown's periphery. The crown's non-circular shape engages with a corresponding feature on the housing, reversing the traditional location of the coupling mechanism and simplifying manufacturing.
3Ease of operation
If the plug is designed with a compact structure to improve accessibility in cramped engine spaces, then the ease of operation is improved, but the available space for integrating locking mechanisms is reduced
Solution Approach 1:
The locking mechanism is nested within the plug structure itself. The crown with locking teeth is integrated into the plug body, with the helical compression spring housed within the plug's internal volume. The bearing zone allows the crown to move axially within the constrained space of the plug, enabling a compact design that accommodates the locking mechanism without increasing external dimensions.
Solution Approach 2:
The locking mechanism utilizes the axial dimension through the bearing zone, allowing the crown to move along the axis of the plug rather than requiring radial space. This dimensional approach enables the locking mechanism to be compact in the radial direction while providing sufficient space axially for the spring and crown movement, optimizing the plug's overall compactness.
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 solution effectively prevents untimely unscrewing, simplifies manufacturing and assembly, and maintains compactness, ensuring reliable operation even in poorly accessible engine spaces.
Implementation Method 1
cap means (helical compression spring pushing the crown integrated in the cap in the direction of the crown of the housing)
Data Source
Figure 1~2
Figure 3~5
AI summary
The invention relates to a shut-off device comprising a plug (1) intended to be placed over a threaded orifice (2) of a casing (3), or to be removed therefrom, by screwing and unscrewing respectively, the plug comprising a central body (4) bearing a screw thread (5), and locking and unlocking means that oppose the spontaneous unscrewing of the plug and that are activated automatically by the turning of the plug (1) and its corresponding progression in the direction of screwing along a longitudinal axis (X). The locking and unlocking means comprise two releaseable coupling members (7, 8), of which a first member (7) is coupled to and turns with the central body (4) via a protective skirt (10) and of which a second member (8) can be prevented from turning with respect to the casing (3) during screwing.