Bistable Spectacles Knuckle Reducing Hinge Fatigue
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Solution Overview
Problem
Existing eyeglass hinges based on elastic deformation suffer from rapid fatigue and non-reversible elongation, leading to joint play and potential rupture, and require delicate handling during assembly.
Innovation Solution
A bistable hinge system comprising a monolithic elastomer body with bulges and metal cages, allowing movement between open and folded positions without torsional stress, and enabling easy assembly with reduced material bending and improved durability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If an elastic hinge based on torsional deformation of a plastic element is used, then the hinge provides elastic deformation and movement between positions, but the plastic element suffers rapid fatigue and non-reversible elongation leading to joint play and potential rupture
Solution Approach 1:
The patent changes the deformation mode from torsional to flexural/bending. The elastic element is designed to deform primarily through bending along its length rather than twisting, which fundamentally alters the stress distribution and fatigue characteristics of the material.
Solution Approach 2:
The elastic element is segmented into multiple zones with different functions: a central deformation zone that flexes, and end zones that engage with the hinge components. This segmentation allows the critical deformation to occur in a controlled region away from the connection points, reducing stress concentration and fatigue at the joints.
2Ease of operation
If an elastic element is used in the hinge, then the hinge allows movement between open and closed positions, but the element requires delicate handling during assembly due to tension requirements
Solution Approach 1:
The elastic element is pre-formed with the correct curvature and deformation characteristics before assembly. The bending zones are pre-configured to engage properly with the hinge components, eliminating the need for delicate tensioning operations during assembly. The element can be installed in a relaxed state and will automatically assume its functional shape.
3Ease of operation
If a conventional joint is used, then the arm can oscillate freely from open to closed position, but the joint lacks bistability and cannot maintain fixed positions
Solution Approach 1:
The hinge transitions from a passive conventional joint to an active bistable system. The elastic element's flexural properties create two stable equilibrium positions (open and closed) with an unstable intermediate position. The system dynamically switches between these states while maintaining stability at each extreme position without requiring external forces or mechanisms.
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 provides a durable and easy-to-assemble hinge system that maintains stability without oscillation, reduces material fatigue, and ensures secure fit without the need for precise tensioning during assembly.
Implementation Method 1
The hinge element (300) comprises a monolithic body made of an elastomer and having a longitudinal axis, extending along said longitudinal axis between two ends and comprising a central part and two ends, each of said ends comprising a bulge
Data Source
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AI summary
The invention concerns a bistable knuckle element for a spectacles frame, comprising a brachial cage having a bottom extended laterally by two lateral longitudinal walls defining a housing opening on a proximal transverse face by an opening having a U-shaped cross-section, and a solid body elastically deformable along the longitudinal axis, having a central portion, with a cross-section corresponding to the transverse cross-section of said U-shaped openings, extended at each end by a bulging of a cross-section complementary to the transverse cross-section of said housings of the brachial and facial cages.