Sandal Strap Attachment via Nested Stopper Mechanism

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Solution Overview

Problem

Conventional flip-flop sandal designs are fragile during intense movements due to high traction force at attachment points, leading to detachment of the upper from the sole, and existing solutions either fail to provide sufficient resistance or result in discomfort or increased production costs.

Innovation Solution

A structural arrangement with double fitting mechanism, where upper straps with hollow ends pass through cavities in the flexible sole, secured by rigid plastic stoppers with a central pin-shaped structure, providing dual resistance to removal and ensuring firm attachment during intense movements.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional attachment structures are used, then the sandal is simple to manufacture, but the upper detaches during intense movements

Engineering Contradiction:
Improveattachment resistanceVSAvoidattachment structure
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The attachment structure employs a nested configuration where the upper strap passes through a cavity in the sole and is retained by a stopper element positioned at the distal end. The stopper is received within the cavity, creating a nested arrangement that secures the upper to the sole while maintaining structural simplicity.

Inventive Principle:
Principle #7Nested doll (Nesting)

Solution Approach 2:

The attachment mechanism is divided into distinct functional segments: the cavity providing the retention space, the stopper element providing the securing function, and the upper strap providing the attachment medium. This segmentation allows each component to be optimized independently while maintaining overall simplicity.

Inventive Principle:
Principle #1Segmentation

2Reliability

If more attachment structures are added, then resistance to intense movements increases, but user comfort decreases

Engineering Contradiction:
Improveattachment resistanceVSAvoiduser comfort
Core Design Contradiction:
ReliabilityVSEase of operation

Solution Approach 1:

The attachment resistance is concentrated at the distal end of the cavity where the stopper is positioned, rather than distributing attachment points along the entire length of the upper. This localized quality provides sufficient resistance to intense movements while maintaining comfort by avoiding excessive attachment structures.

Inventive Principle:
Principle #3Local quality

3Object-generated harmful factors

If wider uppers are used, then friction and wear are reduced, but user comfort decreases due to excessive width

Engineering Contradiction:
Improvefriction and wearVSAvoiduser comfort
Core Design Contradiction:
Object-generated harmful factorsVSEase of operation

Solution Approach 1:

The cavity and stopper structure provides a cushioning effect by allowing controlled movement and absorption of forces before they reach the upper-sole interface. This beforehand cushioning reduces friction and wear without requiring wider uppers, thereby maintaining user comfort.

Inventive Principle:
Principle #11Beforehand cushioning (Prior cushioning)

Data Source

PatentEP3750443B1sandal
Publication Date: 2023.07.26 TESS IND E COMERCIO LTDA
  • EP3750443B1 patent drawingFigure 1
  • EP3750443B1 patent drawingFigure 2
  • EP3750443B1 patent drawingFigure 3

AI summary

The utility model relates to a structural arrangement for attaching flexible uppers to sandals such as flip-flops, consisting of an upper (2) comprising three longitudinal straps (7, 8 and 9) provided with, in the most distal regions thereof, an upper protuberance (10) in contact with an upper surface (5) of a sole (1), a lower protuberance (11) in contact with a lower surface (6) of said sole (1), and a hollow space (12) that passes through cavities (4) in the sole (1) and receives a stopper (3) made of rigid plastic, said stopper having both a region with a smaller diameter (13) and a region with a larger diameter (14), the latter covering the lower recess (11) of the most distal end of the upper (2), as well as a central hole (15) that connects the inside of the hollow space to the outside environment.