Removable Ski Boot Sole Using Low-Density PPE Foam
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Solution Overview
Problem
Current ski boots fail to balance mechanical support, thermal insulation, and comfort while being lightweight and cost-effective, with existing solutions either compromising on force transmission, thermal insulation, or increasing complexity and weight.
Innovation Solution
A ski boot with a removable shell sole made from a single block of Expanded Polypropylene (PPE) material with a density less than 120 g/l, featuring a heel block and metatarsal plate, which can be adjusted in thickness and equipped with ribs for improved stability and thermal insulation, allowing adaptation of the interior volume and serving as a water drainage system.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a rigid material is used for the removable sole to adapt the interior volume, then the interior volume can be adjusted, but the force transmission between the boot and ski deteriorates and thermal insulation is reduced due to thermal bridges
Solution Approach 1:
The patent changes the material parameter (density) of the removable sole to less than 120 g/l, specifically using expanded polypropylene (PPE). This parameter change allows the sole to provide thermal insulation while maintaining adequate mechanical support for force transmission, resolving the contradiction between interior volume adaptation and force transmission reliability.
Solution Approach 2:
The patent uses expanded polypropylene (PPE), a composite material with air pockets distributed throughout the structure. This composite structure provides both the rigidity needed for interior volume adaptation and the thermal insulation properties that prevent thermal bridges, while maintaining force transmission capabilities.
2Strength
If a rigid material with high density is used for the removable sole, then mechanical support and force transmission are improved, but thermal insulation deteriorates and weight increases
Solution Approach 1:
The patent specifies a density parameter of less than 120 g/l for the removable sole material. This parameter change creates a material that is light enough for thermal insulation but still provides adequate mechanical support through the expanded foam structure's inherent rigidity.
Solution Approach 2:
The patent employs expanded polypropylene (PPE), a porous material with air pockets distributed throughout. The porous structure provides thermal insulation by trapping air while the expanded foam structure maintains mechanical support properties, resolving the contradiction between strength and thermal insulation.
3Adaptability or versatility
If two separate parts are assembled to form the sole, then modularity is achieved, but the weight and complexity of the boot increase
Solution Approach 1:
The patent merges the heel block and metatarsal plate into a single integrated removable sole made of expanded polypropylene. This merging reduces the total weight compared to two separate parts while maintaining modularity through the removable design, and simplifies the assembly process.
Solution Approach 2:
The use of expanded polypropylene as a composite material allows the entire sole structure to be manufactured as a single lightweight piece with integrated features, reducing weight while maintaining the adaptive functionality previously requiring separate components.
4Stability of the object's composition
If ribs are added to the removable sole for structural support, then mechanical stability is improved, but thermal bridges are created that reduce thermal insulation
Solution Approach 1:
The patent uses expanded polypropylene with a porous structure that provides mechanical stability through the foam's inherent rigidity rather than dense ribs. The porous structure maintains thermal insulation by trapping air throughout, avoiding the thermal bridge effect that solid ribs would create.
Solution Approach 2:
The patent changes the material density parameter to less than 120 g/l, creating a material where the expanded foam structure itself provides the necessary mechanical stability without requiring additional rib structures that would compromise thermal insulation.
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 solution provides a lightweight, robust, and thermally insulated ski boot with excellent force transmission and adjustable volume, enhancing user comfort and reducing production complexity and costs.
Implementation Method 1
the removable sole has a particularly low weight and excellent properties in terms of thermal insulation
Implementation Method 2
the ribs function as thermal bridges which cool the foot
Data Source
Figure 1a
Figure 1b
Figure 2a~2b
AI summary
The boot (10) has a shell (1), an internal slipper (4) and a removable shell bottom sole (5) that includes a heel pad (5.1) and a metatarsal plate (5.2). The pad and the plate are formed from a single block of material e.g. expanded poly propylene, having density lower than 120 grams per liter. The pad has thickness (5.1.1) greater than 10 mm preferably greater than 15 mm. The metatarsal plate has thickness (5.2.1) lower than the thickness of the pad and greater than 4 mm, preferably greater than 5 mm. The material has hardness greater than 65 Shore A.