Variable Stiffness Shoe Sole Stabilizer for Pronation Control
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Solution Overview
Problem
Existing footwear technologies fail to precisely and smoothly control the motion of the foot along a foot strike path and provide a continuous transition in compression resistance, leading to issues with excessive pronation and supination that can result in injuries.
Innovation Solution
A stabilizing device with a continuously varying stiffness and cross-sectional area is integrated into the shoe sole, specifically designed to extend from the medial or lateral side across 20% to 35% of the shoe's width at the arch region, using thermoplastic materials to provide precise control over foot motion by adjusting stiffness from the rearfoot to the arch region.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If discrete rigid posts and plates or dual density midsole foams are used to control foot motion, then pronation and supination can be controlled, but the transition in compression resistance is discontinuous and limited to one direction
Solution Approach 1:
The patent applies parameter changes by varying the density of the foam material continuously along the longitudinal axis of the shoe. The foam density increases from the heel region toward the forefoot region, creating a continuous gradient in compression resistance. This resolves the contradiction by enabling smooth, continuous transition in stiffness while maintaining effective foot motion control throughout the gait cycle.
Solution Approach 2:
The patent implements local quality by creating regions of different foam densities within the same midsole structure. The heel region has lower density for cushioning, while the forefoot region has higher density for stability and propulsion. This spatial variation in material properties enables continuous transition in compression resistance while maintaining reliable pronation and supination control.
2Reliability
If medial posting systems use firmer density foam on the medial side, then pronation can be controlled, but the density and hardness control is difficult and manufacturing is more costly
Solution Approach 1:
The patent uses parameter changes by implementing a continuous density gradient throughout the foam structure rather than discrete density zones. This is achieved through controlled foaming processes that vary density continuously along the longitudinal axis, making the transition smoother and more predictable than traditional dual-density systems. This resolves the manufacturing difficulty while maintaining effective pronation control.
3Reliability
If dual density foam wedges are used to provide smoother transition, then pronation control is improved, but the positioning and thickness control is difficult during manufacturing
Solution Approach 1:
The patent merges the cushioning function and motion control function into a single integrated foam structure with continuous density variation. Instead of positioning separate wedge elements within the midsole, the density gradient is built into the foam itself, eliminating positioning errors and ensuring consistent thickness and transition characteristics throughout production.
Solution Approach 2:
The patent applies parameter changes by creating a continuous density gradient that eliminates the need for discrete wedge positioning. The foam density transitions smoothly from heel to forefoot, providing both cushioning and motion control in a single manufactured component with precise, repeatable geometry.
Data Source
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AI summary
The present invention provides a stabilizing device that helps to prevent over-pronation or over-supination and a shoe which includes such a stabilizing device. The stabilizing device is provided along a side of the midsole and preferably extends laterally between about 20% and about 35% of a width of the sole towards the opposite side thereof. The stabilizing device includes an elongated portion and a sidewall portion that extends transversely from the elongated portion. The sidewall portion forms part of an outer peripheral wall of the shoe. The sidewall portion has a stiffness which varies along the length of the stabilizing device to provide a predetermined support profile along the side of the sole. The elongated portion can also vary in stiffness along its length. The stabilizing device can be formed of a resilient material using an injection molding procedure or similar technique.