Fluid-Filled Midsole Chamber Bonding for Durable Cushioning
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Solution Overview
Problem
Conventional polymer foam midsoles in athletic footwear deteriorate with repeated compressions, leading to decreased compressibility and force attenuation due to the cell structure degradation, which affects the overall performance and comfort during ambulatory activities.
Innovation Solution
Incorporating a fluid-filled chamber within the midsole, where a tensile member with varying compressibility is bonded to polymer layers, and the assembly is molded to form a sealed enclosure that maintains pressure and shape, enhancing the midsole's durability and cushioning.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional polymer foam materials are used for the midsole, then the midsole provides initial cushioning and force attenuation, but the cell structure deteriorates with repeated compressions leading to decreased compressibility and force attenuation
Solution Approach 1:
The patent replaces conventional polymer foam with a fluid-filled chamber system where pressurized gas or liquid is contained within sealed chambers. This pneumatic/hydraulic system provides sustained force attenuation without the cell structure deterioration that plagues foam materials, as the fluid pressure can be maintained indefinitely without degradation
Solution Approach 2:
The patent utilizes the compressibility characteristics of gases versus liquids to create different midsole performance profiles. By selecting appropriate fill fluids and adjusting chamber pressure, the system can be tuned to provide desired cushioning characteristics that maintain their properties over time without the degradation seen in foam materials
2Weight of moving object
If a fluid-filled chamber is incorporated into the midsole, then the mass of the midsole is reduced and deterioration effects are decreased, but the chamber requires additional manufacturing steps and structural components
Solution Approach 1:
The patent employs thin-walled flexible polymer chambers that can be molded into complex three-dimensional shapes. These thin-film structures provide the necessary containment while minimizing added weight, and the flexibility allows the chambers to conform to the midsole geometry and deform under load for cushioning
Solution Approach 2:
The midsole is divided into multiple discrete fluid-filled chambers rather than using a single solid structure. This segmentation allows for weight reduction through strategic placement of chambers only where cushioning is needed, while also simplifying manufacturing by allowing chambers to be produced and assembled separately
3Shape
If tensile members are located within the chamber or reinforcing structures are bonded to the exterior, then the chamber is given shape and structural integrity, but the manufacturing process becomes more complex
Solution Approach 1:
The patent combines the tensile member reinforcement and chamber shaping functions into a single integrated molding operation. The tensile members are positioned within the chamber during the molding process, allowing both the chamber shape and reinforcement structure to be created simultaneously in one manufacturing step rather than requiring separate assembly operations
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
The fluid-filled chamber with a tensile member improves the midsole's ability to maintain cushioning and attenuate ground reaction forces, providing consistent performance and extended durability by distributing compressive forces effectively.
Implementation Method 1
The chambers are then encapsulated in the polymer foam of the midsole such that the combination of the chamber and the encapsulating polymer foam functions as the midsole
Implementation Method 2
compressing the tensile member, the first layer of the polymer material, and the second layer of the polymer material within the mold to (a) bond the first layer to a first surface of the tensile member, (b) bond the second layer to a second surface of the tensile member, and (c) bond the first layer and the second layer together around a periphery of the tensile member
Implementation Method 3
The tensile member has a first portion with greater compressibility than a second portion
Data Source
Figure 1
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AI summary
A fluid-filled chamber may include an outer barrier formed from a polymer material and a foam tensile member located within the outer barrier. In manufacturing the fluid-filled chamber, a mold may be contoured to substantially equalize compressive forces between the outer barrier and various portions of the tensile member, thereby providing substantially uniform bonding between the outer barrier and the tensile member. Surfaces of the tensile member may also be contoured to substantially equalize compressive forces. In some configurations, the outer barrier and tensile member may be formed from thermoplastic polymer materials that form a direct bond between the outer barrier and surfaces of tensile member.