Fluid-Filled Chamber Bonding for Durable Footwear 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 their cell structure, which affects the overall performance and longevity of the sole structure.
Innovation Solution
Incorporating a fluid-filled chamber with a tensile member having varying compressibility into the midsole, where the tensile member is bonded to the polymer layers to restrain deformation and maintain the chamber's shape under pressure, enhancing the midsole's durability and cushioning properties.
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 deteriorating polymer foam cell structure with a fluid-filled chamber that uses hydraulic principles to provide force attenuation. The fluid (water or other incompressible liquid) transmits pressure forces uniformly throughout the chamber, maintaining consistent cushioning performance over time without the degradation issues of foam materials. The chamber is sealed and pressurized to provide reliable, durable force attenuation.
Solution Approach 2:
The patent changes the material parameter from compressible polymer foam to incompressible fluid, fundamentally altering how force attenuation is achieved. The fluid's incompressibility ensures that the chamber maintains its volume and pressure characteristics even after repeated compressions, preventing the deterioration seen in foam materials. This parameter change enables long-term reliability without loss of cushioning performance.
2Duration of action of stationary object
If a fluid-filled chamber is incorporated into the midsole to reduce mass and decrease deterioration effects, then the chamber improves durability, but the chamber requires additional structural components (tensile members or reinforcing structures) to maintain shape
Solution Approach 1:
The patent applies local quality by using tensile members with varying compressibility - the first portion has greater compressibility than the second portion. This allows different regions of the chamber to have different mechanical properties, enabling the chamber to maintain its shape while accommodating localized deformation needs. The varying compressibility distributes stresses more effectively throughout the chamber structure.
Solution Approach 2:
The patent creates a composite structure combining the fluid-filled chamber with tensile members made of foam or textile materials. This composite construction integrates the durability benefits of the sealed fluid chamber with the shape-maintaining properties of the tensile members. The combination achieves both extended service life and proper structural form without requiring overly complex designs.
3Ease of manufacture
If the tensile member has uniform compressibility, then the manufacturing process is simpler, but the compressive forces are not evenly distributed leading to potential deformation
Solution Approach 1:
The patent implements local quality by creating a tensile member with non-uniform compressibility - the first portion has greater compressibility than the second portion. This variation in material properties allows different regions to compress by different amounts, evenly distributing the compressive forces throughout the chamber. The mold protrusion works with this varying compressibility to ensure uniform bonding and proper shape maintenance during operation.
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 attenuate ground reaction forces and maintain cushioning over time, extending the footwear's lifespan and performance by evenly distributing compressive forces and preventing deformation.
Implementation Method 1
The tensile member has a first portion with greater compressibility than a second portion... compressing the tensile member, the first layer of polymer material, and the second layer of polymer material within the mold to bond the layers to the tensile member
Implementation Method 2
The mold has a protrusion in an area that contacts the first layer adjacent to the first portion of the tensile member... compressing the tensile member, the first layer of polymer material, and the second layer of polymer material within the mold to bond the first layer to a first surface of the tensile member
Implementation Method 3
In order to pressurize the chamber, a nozzle or needle connected to a fluid pressure source is inserted into a fill inlet formed in the chamber... the fluid-filled chamber with a tensile member improves the midsole's ability to attenuate ground reaction forces and maintain cushioning over time
Data Source
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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.