Elastic Hinge Projections Limit Rotational Play

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Solution Overview

Problem

Existing elastic hinges for eyeglass frames suffer from significant play in rotation due to the accumulation of mechanical play between the tenon and knuckle, and between the slide and housing, leading to potential breakage of the rod under bending forces and inadequate resistance to rotational forces.

Innovation Solution

An elastic hinge design featuring a housing with projections that engage between the flanges of the tenon to ensure direct mechanical coupling, limiting the angle of rotation and reducing lateral clearance, while using a spring mechanism to restore the slide to a retracted position, thereby eliminating unnecessary rotational movements and enhancing structural integrity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If the flanges are made larger to ensure effective guiding of the slide, then the guiding of the slide is improved, but the resistance of the tenon against rotational forces deteriorates

Engineering Contradiction:
Improveguiding precisionVSAvoidresistance to rotational forces
Core Design Contradiction:
Manufacturing precisionVSStrength

Solution Approach 1:

The patent divides the guiding function from the rotational resistance function by introducing a separate guide zone with guide surfaces. The flanges are no longer responsible for guiding the slide but only for providing rotational resistance through their connection to the tenon. This segmentation allows each component to be optimized for its specific function without compromise.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent introduces an intermediary guide zone with guide surfaces that mediate between the slide and the flanges. This intermediary structure handles the guiding function, allowing the flanges to focus on providing rotational resistance. The guide zone acts as a mediator that transfers guiding responsibilities away from the flanges.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Manufacturing precision

If the projections are made longer to ensure effective guiding, then the guiding is improved, but the rotational play increases

Engineering Contradiction:
Improveguiding accuracyVSAvoidrotational stability
Core Design Contradiction:
Manufacturing precisionVSStability of the object's composition

Solution Approach 1:

The patent segments the guiding function into a dedicated guide zone with guide surfaces, separate from the projections that connect to the flanges. The projections are shortened and only serve to engage with the flanges for rotational stability, while the guide zone handles guiding accuracy. This segmentation eliminates the conflict between projection length and rotational stability.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The guide zone with guide surfaces acts as an intermediary between the slide and the flange connection. It provides the necessary guiding accuracy without requiring long projections, thereby maintaining rotational stability while achieving precise guiding.

Inventive Principle:
Principle #24Intermediary (Mediator)

3Strength

If the mechanical coupling between tenon and slide is strengthened, then the resistance to rotational forces is improved, but the lateral clearance increases

Engineering Contradiction:
Improveresistance to rotational forcesVSAvoidlateral clearance
Core Design Contradiction:
StrengthVSManufacturing precision

Solution Approach 1:

The patent segments the mechanical coupling into two separate functions: rotational resistance provided by the flange-tenon connection, and lateral guidance provided by the guide zone with guide surfaces. This segmentation allows the mechanical coupling to be strengthened for rotational resistance without increasing lateral clearance, as the guide zone maintains precise lateral positioning.

Inventive Principle:
Principle #1Segmentation

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 reduces play in the hinge mechanism, enhancing the resistance to rotational forces and preventing the hinge from moving apart, thus ensuring a secure and stable connection between the temple and frame without compromising the slide's guidance.

Implementation Method 1

a return spring (19) for restoring the slide (2) to a retracted position towards the inside of the housing (12)

Methodology Applied
Scientific EffectElasticity: Elasticity

Data Source

PatentEP2109795B1Compact elastic hinge for spectacle frames
Publication Date: 2012.01.25 MAZZUCCHELLI INT
  • EP2109795B1 patent drawingFigure 1~3
  • EP2109795B1 patent drawingFigure 4~5
  • EP2109795B1 patent drawingFigure 6~7

AI summary

The invention relates to an elastic hinge for spectacle frames comprising: a tenon (3) comprising two parallel plates (31a, 31b) supporting a hinge pin (35), a casing (1) comprising a longitudinal housing (12) comprising a guide region (15), a runner (2) arranged in the housing (12), comprising a projecting part (25) which extends out of the housing and is sandwiched between the two plates by the hinge pin and a guided part (23) collaborating with the guide region (15), and elastic means (19) for returning the runner to a position in which it is retracted inside the housing. According to the invention, the casing (1) comprises at least one protrusion (13a, 13b) that does not guide the runner (2) and that extends from the casing in order to fit between the two plates (31a, 31b) so as to provide direct mechanical coupling between the casing and the tenon (3).