Pivoting Multi-Member Heel Strap for Hands-Free Sandal Entry
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Solution Overview
Problem
Existing sandals require users to bend down and use their hands to put them on or take them off, and existing easy-entry shoes do not provide a comfortable fit or are not cost-effective.
Innovation Solution
A sandal design featuring a heel strap with multiple strap members made of firm materials and elastic members that pivot and stretch to accommodate the foot without requiring manual adjustment, allowing hands-free entry and exit.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If traditional sandal straps are used requiring manual adjustment, then the sandal provides a secure fit, but the user must bend down and use hands to put it on and take it off
Solution Approach 1:
The heel strap assembly is designed to automatically pivot downward when the user's foot enters the sandal opening and automatically return to its original position when the foot is removed, eliminating the need for manual adjustment. The elastic members provide the restoring force that returns the strap to its initial position, creating a self-service mechanism that resolves the contradiction between ease of operation and device complexity.
Solution Approach 2:
The heel strap assembly is made dynamically movable through pivoting joints that allow the strap to move between different positions. The elastic members create a dynamic system that automatically adjusts to the user's foot entry and exit, transforming a static strap structure into a dynamic one that adapts to user actions without requiring manual intervention.
2Ease of operation
If easy-entry shoe mechanisms are used, then hands-free entry is enabled, but the fit is not comfortable or the production cost increases
Solution Approach 1:
The heel strap is divided into multiple separate members (medial strap member, lateral strap member, rear strap member) connected by elastic members. This segmentation allows each component to be manufactured independently using simple, cost-effective processes while collectively providing the hands-free entry function. The modular structure reduces production complexity compared to integrated mechanisms.
Solution Approach 2:
The elastic members change their physical parameters (length, tension) in response to foot entry, automatically adjusting the strap position without requiring complex mechanical structures. This parameter-based approach using material properties rather than complex mechanisms reduces production costs while maintaining hands-free entry capability.
3Ease of operation
If the heel strap is made flexible for easy entry, then hands-free placement is enabled, but the strap may deform under applied forces
Solution Approach 1:
The heel strap is designed as a dynamic structure that pivots on fixed points rather than deforming. The pivoting joints allow the strap to change position during foot entry while the firm material maintains the strap's structural integrity and prevents unwanted deformation. This dynamic positioning with structural stability resolves the contradiction between flexibility and shape stability.
Solution Approach 2:
Different parts of the strap system have different properties: the connection points use firm, stable materials to maintain structural integrity, while the elastic members provide localized flexibility where needed. This local differentiation of material properties allows the strap to be flexible where required for entry while maintaining overall shape stability.
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
Enables easy and comfortable hands-free entry and exit of sandals without bending down, while being cost-effective to produce.
Implementation Method 1
wherein when the heel strap is pivoted downward, the anterior medial elastic member and the anterior lateral elastic member are stretched, and wherein once the downward force is removed, the stretched anterior lateral elastic member draws the lateral strap member to pivot upward, the stretched anterior medial elastic member draws the medial strap member to pivot upward
Data Source
Figure 1A
Figure 1B
Figure 2
AI summary
A sandal (10) comprising an upper (11) and a heel strap (14) made of at least five members (23, 24, 29, 30, 31), including three firm members (23, 24, 29) and two elastic members (30, 31). The heel strap is allowed to pivot relative to the upper, wherein a rear part of the heel strap is allowed to further pivot relative to the anterior heel strap members. The sandal includes elastic members (19, 20) that are stretched while the heel strap pivots downward under a downward force on the heel strap while a foot slides into the sandal. The elastic members force the heel strap to pivot upward when the downward force is released.