Oval Snap Hook Belt Connector Anti-Disengagement
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Solution Overview
Problem
Existing snap hooks used in bags, such as shoulder bags and backpacks, face issues with disengagement due to their design, which results in reduced strength and usability, especially when the components are not aligned orthogonally.
Innovation Solution
The connector features a snap hook and belt connecting member with bulging portions and fitting holes of oval shape, allowing for increased engaging strength by varying the contacting area based on rotational positions, ensuring secure engagement and preventing unintentional disengagement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If circular-shaped enlarging portions and fitting holes are used in snap hooks, then the structure is simple and easy to manufacture, but the engaging strength is reduced and disengagement occurs easily when components are not orthogonally aligned
Solution Approach 1:
The patent applies asymmetry by changing the fitting hole shape from circular to oval. The oval shape has a major axis and minor axis that create directionally-dependent engagement characteristics. When the belt connecting member and snap hook body are orthogonally aligned, the oval shape maximizes contacting area and engaging strength. This asymmetric geometry prevents easy disengagement while maintaining manufacturability through standard molding processes.
Solution Approach 2:
The patent transitions from a two-dimensional circular cross-section to a three-dimensional oval configuration with distinct major and minor axes. This dimensional change allows the engaging portion and engaged portion to interact across multiple planes, increasing the effective contacting area when properly aligned. The oval geometry introduces a new dimension of engagement control that circular shapes cannot provide.
2Device complexity
If circular-shaped enlarging portions and fitting holes are used in snap hooks, then the structure is simple, but disengagement occurs easily when the holding member and hook main body are not orthogonally aligned
Solution Approach 1:
The oval-shaped fitting hole and engaging portion create asymmetric engagement characteristics that provide directional stability. The major axis of the oval aligns with the orthogonal position, creating maximum resistance to disengagement in that orientation. This asymmetric design naturally guides proper alignment and prevents accidental disengagement while maintaining relatively simple structure.
Solution Approach 2:
The oval geometry pre-establishes geometric constraints that prevent disengagement before it can occur. The shape itself creates inherent resistance to movement in directions other than the intended engagement axis, providing preliminary anti-action against unwanted disengagement without requiring additional locking mechanisms or complex structures.
3Strength
If oval-shaped bulging portions and fitting holes are used, then the contacting area varies with rotational position providing secure engagement, but the manufacturing precision requirements increase
Solution Approach 1:
The oval shape provides asymmetric geometry that naturally indicates the correct engagement orientation. The major and minor axes create a unique geometric signature that guides proper alignment during assembly. This asymmetric design reduces the need for high-precision manufacturing by providing self-aligning characteristics that tolerate reasonable variations in manufacturing tolerances.
Solution Approach 2:
The patent changes the geometric parameters of the fitting hole from circular (equal dimensions in all directions) to oval (different major and minor axis lengths). This parameter change creates a shape that is more tolerant to manufacturing variations while still providing the desired engagement strength when properly aligned. The oval geometry maintains functional performance across a wider range of manufacturing tolerances compared to circular designs.
Data Source
AI summary
To connect a belt connecting member (4) of a first member (1) with a snap hook (5) of a second member (2), a neck portion (21) having a circular cross section is provided so as to project from a connecting portion of the snap hook (5), a bulging portion (22) is provided on a tip end of the neck portion (21) so as to radially bulge to define an engaging portion (23), a fitting hole (13) is provided on a connecting portion of the belt connecting member (4) with an engaged portion (15) that is engageable with the bulging portion (22), the engaged portion (15) and the engaging portion (23) are formed in an oval shape having a long axis (L, L′) in a flush plane of the belt connecting member (4) and the snap hook (5) and a short axis (S, S′) in orthogonal planes of the belt connecting member (4) and the snap hook (5), and the engaging force can be largest when the snap hook (5) is in its most general state in use where the belt connecting member (4) and the snap hook (5) are orthogonal.