Self-Locking Plug With Flexible Beam Fingers
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Solution Overview
Problem
Existing self-locking borescope plugs in aircraft engines are prone to loosening and require special tools or knowledge for operation, and they often have sharp edges, loose parts, or complex designs.
Innovation Solution
A self-locking plug design featuring a body component with a flange and flexible beam fingers, an annular detent ring, and a biasing component, which provides a secure locking mechanism without sharp edges or loose parts, and can be easily assembled and rotated to prevent loosening, using a wave spring for biasing force and tabs for anti-rotation features.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional secondary locking features (safety wire, tab washers, cotter clips) are used, then the plug can be secured against loosening, but the design becomes complex and requires special tools or knowledge for operation
Solution Approach 1:
The plug incorporates self-locking features that automatically engage and lock the plug in place without requiring external tools or special knowledge for operation. The locking mechanism is integrated into the plug body itself, allowing it to secure against loosening through its own structural features rather than requiring separate locking components.
Solution Approach 2:
The invention combines the sealing function and locking function into a single integrated plug design. The flexible beam fingers serve both as sealing elements and as locking features that engage with the engine case, eliminating the need for separate locking components like safety wire or tab washers.
2Reliability
If traditional secondary locking features are used, then the plug can be secured, but sharp edges and loose parts are introduced that may cause damage
Solution Approach 1:
The plug uses flexible beam fingers made of elastomeric material that provide both sealing and locking functions. These flexible elements eliminate sharp edges by using compliant, rounded surfaces that engage with the engine case, and prevent loose parts by integrating the locking function into the flexible beam structure itself rather than using separate metal locking components.
3Reliability
If a self-locking mechanism is implemented, then reliability is improved, but the plug design becomes more complex
Solution Approach 1:
The plug is divided into distinct functional segments: the body component for threading and sealing, the flexible beam finger component for locking and sealing, and the biasing component for maintaining force. This segmentation allows each component to be optimized for its specific function while keeping the overall design relatively simple and manufacturable.
Solution Approach 2:
The flexible beam fingers are designed to be dynamically compliant rather than rigid, allowing them to flex during installation and operation. This dynamic flexibility provides the locking force needed for reliability while using simple elastomeric material rather than complex mechanical spring systems.
4Reliability
If multiple components are used for self-locking, then reliability improves, but manufacturing complexity and weight increase
Solution Approach 1:
The biasing component is nested within the body component, and the flexible beam finger component is integrated with the body flange. This nesting arrangement allows multiple functional components to be assembled in a compact configuration that reduces overall complexity and facilitates manufacturing while maintaining the self-locking reliability.
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 design ensures the plug remains securely seated, is resistant to failure, and is compact and lightweight, with a simple, tool-free operation that enhances reliability and maintainability.
Implementation Method 1
the plurality of flexible beam fingers travel across the plurality of detents to cause elastic deformation of the flexible beam fingers when the body component is rotated about the central, longitudinal axis, A, of the self-locking plug
Implementation Method 2
the plurality of flexible beam fingers travel across the plurality of detents to cause elastic deformation of the flexible beam fingers when the body component is rotated about the central, longitudinal axis, A, of the self-locking plug
Data Source
AI summary
A compact, highly-reusable, self-locking includes a body component, a flexible beam finger component with a plurality of axially-oriented flexible beam fingers and one or more outwardly extending tabs, an annular detent ring component including a plurality of detents in radial alignment with the plurality of flexible beam fingers, and a biasing component engaging the flange of the flexible beam finger component and the annular detent ring component for providing a biasing force to urge the flexible finger beam component in a direction of a central, longitudinal axis of the self-locking plug. The flexible beam finger component moves relative to the annular detent ring component when the body component is rotated about the central, longitudinal axis, A, of the self-locking plug, thereby causing the plurality of flexible beam fingers to travel across the plurality of detents and cause elastic deformation of the flexible beam fingers.