Shoe Assembly Snap-Fit Sole Connection
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Solution Overview
Problem
The existing shoe assembly with a snap-fit connection between the outer sole and the connecting sole is difficult and expensive to manufacture, and the fixation is not reliable, especially under side forces when stepping on the outer sole rim, requiring additional hook-and-loop-fasteners for stability.
Innovation Solution
A shoe assembly design featuring a first connecting means as an upwardly extending circumferential lug on the connecting sole and a second connecting means with a hook-shaped cross section at the free end of the outer sole's rim, allowing for a one-piece construction of both components and ensuring a strong, reliable snap-fit connection without additional fixing means.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the outer sole and connecting sole are constructed with complex multi-layer sponge rubber and recess-providing parts, then the snap-fit connection can be achieved, but the manufacturing cost and complexity increase significantly
Solution Approach 1:
The connecting sole is divided into three distinct layers: an upper layer, a middle layer with recesses, and a lower layer. This segmentation allows each layer to perform its specific function - the recesses in the middle layer engage with protrusions in the outer sole to create the snap-fit connection, while the upper and lower layers provide structural support and cushioning.
Solution Approach 2:
The recess-providing middle layer is nested between the upper and lower layers of the connecting sole. The recesses are formed within this intermediate layer, creating a nested structure where the connection mechanism is embedded within the sole construction rather than being a separate component.
2Ease of manufacture
If the outer sole rim is made with an upwardly protruding circumferential rim, then the snap-fit connection can be formed, but the connection releases under side forces when stepping
Solution Approach 1:
The circumferential rim is extended upwardly from the outer sole, adding a vertical dimension to the connection structure. This upward extension creates a taller engagement profile that resists side forces better than a flat rim would, while still maintaining the simplicity of a one-piece rubber component.
Solution Approach 2:
The circumferential rim is designed with a curved profile rather than a straight edge. The rounded shape distributes stresses more effectively and provides better mechanical engagement with the recess-providing layer, preventing the connection from releasing under lateral loads during stepping.
3Reliability
If additional hook-and-loop fasteners are added to ensure reliable fixation, then the connection stability improves, but the manufacturing complexity and cost increase
Solution Approach 1:
The snap-fit connection mechanism is integrated directly into the structure of the outer sole and connecting sole themselves. The circumferential rim with upward projection and the recess-providing middle layer work together as a unified mechanical interlocking system, eliminating the need for separate fastening components like hook-and-loop fasteners.
Solution Approach 2:
The outer sole and connecting sole are designed to self-lock through their geometric features. The upwardly protruding circumferential rim engages with the recesses in the middle layer to create automatic mechanical retention, and the undercut projection provides self-retaining engagement without requiring additional active fastening mechanisms.
Data Source
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AI summary
Shoe assembly (1) comprising an upper shoe part (2), an inner sole (3), a connecting sole (4) fixed to the inner sole (3) and an outer sole (5), which is fixed to the connecting sole (4) by means of a manually detachable snap-fit connection, wherein the snap-fit connection comprises first connecting means (8) provided at and upwardly protruding from the connecting sole (4), and second connecting means (9) provided at a free end of an upwardly protruding circumferential rim (10) of the outer sole (5) and encompassing the first connecting means (8), when the outer sole (5) is fixed to the connecting sole (4).