Fluid-Filled Chamber Bonding for Durable Midsole 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 longevity of the sole structure.
Innovation Solution
Incorporating a fluid-filled chamber with a tensile member having a first portion with greater compressibility than a second portion, where the tensile member is bonded between two layers of polymer material within a mold, allowing for enhanced bonding and retention of the chamber's shape under pressure, thereby maintaining the midsole's cushioning and support.
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 the conventional polymer foam midsole with a fluid-filled chamber that uses hydraulic principles. The fluid (liquid or gas) inside the chamber provides continuous cushioning and force attenuation without the cell structure deterioration that occurs in foam materials. The fluid transmits compressive forces uniformly, maintaining consistent performance over time and resolving the durability issue of conventional foams.
Solution Approach 2:
The invention changes the physical state and properties of the cushioning medium from solid foam cells to fluid under pressure. By adjusting fluid pressure, volume, and type (liquid vs. gas), the system maintains optimal cushioning characteristics throughout the product lifecycle, preventing the degradation seen in conventional foam materials.
2Weight of moving object
If a fluid-filled chamber is incorporated into the midsole, then mass is reduced and deterioration effects are decreased, but the chamber requires additional structural components (tensile members, bonding layers) to maintain shape and functionality
Solution Approach 1:
The patent applies local quality by creating a tensile member with a protrusion in a specific location where the chamber requires additional structural support. This localized reinforcement allows the chamber to maintain its shape and bonding integrity without adding complex structures throughout the entire chamber, thus minimizing overall device complexity while achieving the necessary structural performance.
Solution Approach 2:
The invention segments the chamber structure into distinct functional components: the fluid-filled chamber itself, the tensile member with differentiated portions (including the protrusion), and the bonding layers. This segmentation allows each component to be optimized independently for its specific function while keeping the overall system relatively simple.
3Ease of manufacture
If a tensile member with uniform structure is used in the fluid-filled chamber, then manufacturing is simplified, but the chamber cannot adequately restrain deformation in areas requiring different levels of support
Solution Approach 1:
The patent implements local quality in the tensile member by creating a protrusion in a specific area that requires additional shape restraint. This localized structural variation allows the tensile member to provide differential support - stronger in areas prone to deformation, and simpler in areas that require less support - thereby maintaining excellent shape retention without significantly complicating the manufacturing process.
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 maintains the midsole's compressibility and force attenuation characteristics over time, providing improved durability and performance by restraining deformation and maintaining the chamber's shape under pressure.
Implementation Method 1
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
Implementation Method 2
the combination of the chamber and the encapsulating polymer foam functions as the midsole... Suitable polymer foam materials for the midsole include ethylvinylacetate or polyurethane that compresses resiliently under an applied load to attenuate ground reaction forces
Implementation Method 3
The tensile member then restrains outward movement of opposite sides of the chamber when inflated with a pressurized fluid
Data Source
Figure 1
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Figure 3~4
AI summary
A fluid-filled chamber (40) may include an outer barrier (51, 52) formed from a polymer material and a foam tensile member (60) 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.