Slide Fastener With Curved Elements for Lower Coupling Force

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Solution Overview

Problem

Conventional slide fasteners require significant force for coupling fastener elements, making them difficult for physically weak individuals such as infants or the elderly to operate.

Innovation Solution

The slide fastener design features a unique configuration of fastener elements with bent or curved shapes and specific protrusions and recesses that reduce interference between elements, allowing for easier coupling with reduced force.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If conventional straight fastener elements are used, then structural integrity is maintained, but the force required to couple elements becomes too large for physically weak individuals

Engineering Contradiction:
ImproveForce required to couple fastener elementsVSAvoidCoupling strength of fastener elements
Core Design Contradiction:
Ease of operationVSStrength

Solution Approach 1:

The fastener elements are designed with bent or curved shapes instead of straight configurations. This curvature reduces the interference between adjacent elements during coupling, allowing the slider to move more easily while maintaining coupling strength through proper engagement geometry of the curved surfaces.

Inventive Principle:
Principle #14Spheroidality (Curvature)

Solution Approach 2:

The fastener element is divided into distinct functional portions: a base portion for attachment to the fastener tape and a terminal portion with engagement features. This segmentation allows optimization of each portion's geometry independently, with the terminal portion designed for easy coupling and the base portion for secure attachment.

Inventive Principle:
Principle #1Segmentation

2Area of stationary object

If fastener elements are arranged with narrow spacing, then the fastener width is reduced, but the interference between elements increases coupling force requirement

Engineering Contradiction:
ImproveWidth of fastenerVSAvoidForce required to move slider
Core Design Contradiction:
Area of stationary objectVSEase of operation

Solution Approach 1:

The bent shape of the fastener elements creates clearance between adjacent elements even when tightly spaced, as the curved terminal portions follow a path that avoids direct interference with neighboring elements, enabling narrow fastener width without increasing coupling force.

Inventive Principle:
Principle #14Spheroidality (Curvature)

Solution Approach 2:

The engagement features utilize three-dimensional curved surfaces rather than planar contacts. This dimensional approach allows elements to engage through controlled surface contact that reduces lateral interference, enabling tighter spacing while maintaining ease of operation.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

Data Source

PatentEP3643194B1Slide fastener
Publication Date: 2025.07.09 YKK CORP
  • EP3643194B1 patent drawingFigure 1
  • EP3643194B1 patent drawingFigure 2~3
  • EP3643194B1 patent drawingFigure 4

AI summary

A slide fastener (100) comprising: a pair of left and right fastener stringers (10) wherein each fastener stringer (10) includes a fastener tape (15) and a plurality of fastener elements (20) attached to the fastener tape (15), each fastener element (20) including a base portion (21) secured to the fastener tape (15) and a terminal portion (22) positioned opposite to the base portion (21); and at least one slider (40) for opening and closing the pair of left and right fastener stringers (10), wherein each of the fastener elements (20) at the left and right sides has an intermediate portion (23) including bent or curved portion between the terminal portion (22) and the base portion (21), the intermediate portion (23) has an engaging protrusion (24) and an engaged recess (25) which are respectively protruded and recessed on an axis (CL) that matches a movement direction of the slider (40), and the fastener element (20) at one side of the left and right sides has at least one displacement-restricting portion (30) that prevents displacement, along an up-down direction, of the fastener element (20) at the other side of the left and right sides.