Footwear Heel Spring Mechanism for Hands-Free Entry in Soft Uppers

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Solution Overview

Problem

Traditional footwear requires the use of one or both hands to stretch the ankle opening and hold the rear portion during foot insertion, especially in soft uppers without a heel counter.

Innovation Solution

A heel spring device with a control bar and base that allows hands-free foot entry by storing elastic energy, enabling the foot to be slid into a foot-receiving cavity, and automatically returning to its original position, thus facilitating easy insertion.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If a soft upper without heel counter is used, then comfort and flexibility are improved, but ease of insertion deteriorates requiring manual assistance

Engineering Contradiction:
Improvecomfort and flexibilityVSAvoidease of insertion
Core Design Contradiction:
Adaptability or versatilityVSEase of operation

Solution Approach 1:

The heel spring device is pre-loaded during foot insertion, storing elastic energy that automatically performs the action of opening the ankle opening and holding the rear portion, eliminating the need for manual assistance

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The heel spring device uses the insertion force itself to activate the spring mechanism, which then automatically returns to its original position to secure the foot, making the system self-servicing without external manual intervention

Inventive Principle:
Principle #25Self-service

2Ease of operation

If hands-free foot entry is enabled, then ease of operation is improved, but device complexity increases due to spring mechanism

Engineering Contradiction:
Improvehands-free foot entryVSAvoidspring mechanism structure
Core Design Contradiction:
Ease of operationVSDevice complexity

Solution Approach 1:

The heel spring device serves multiple functions: it acts as a structural support element, an energy storage mechanism, and an automatic positioning system, all within a single integrated component that attaches to the footwear upper

Inventive Principle:
Principle #6Universality (Multi-functionality)

Solution Approach 2:

The control bar and base are designed as slender, flexible elements that can elastically deform during insertion and recovery, achieving the required functionality with minimal material and structural complexity

Inventive Principle:
Principle #30Flexible shells and thin films

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 hands-free foot entry into footwear by using the heel spring device to store and release elastic energy, allowing the foot to be easily inserted without manual assistance.

Implementation Method 1

The control bar is biased to an unloaded position with the center segment a first distance from the base, and elastically bends under an applied force to a loaded position with the center segment a second distance from the base less than the first distance. The device stores potential energy, such as elastic energy and/or spring energy, that returns the control bar to the unloaded position upon removal of the applied load.

Methodology Applied
Scientific EffectElastic energy storage: Elasticity

Data Source

PatentEP3984400B1Footwear heel spring device
Publication Date: 2025.08.06 NIKE INNOVATE CV
  • EP3984400B1 patent drawingFigure 1~2
  • EP3984400B1 patent drawingFigure 3~4
  • EP3984400B1 patent drawingFigure 5~6

AI summary

A device configured to surround a portion of a foot-receiving cavity at a heel region of an article of footwear comprises a control bar having a center segment, a first side arm extending from the center segment, and a second side arm spaced from the first side arm and extending from the center segment. The control bar may include a series of slats. A base supports the control bar and is connected to the first side arm and the second side arm. The control bar is biased to an unstressed position with the center segment a first distance from the base, and elastically bends under an applied force to a loaded position with the center segment a second distance from the base less than the first distance. The device stores potential energy that returns the control bar to the unloaded position upon removal of the applied load.