Pneumatic Tire Sidewall Concavity Lateral Stability
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Solution Overview
Problem
Conventional pneumatic tires lack stability under lateral forces due to their inability to bear in-plane compression, leading to collapse and reduced stability when subjected to vertical load or reduced air pressure, as the sidewalls tend to deform excessively.
Innovation Solution
A pneumatic tire design featuring an annular sidewall concavity with a non-stretchable tread and bead regions, incorporating a girth-limiting configuration and radial reinforcing structure to maintain the concavity, utilizing threads and radially aligned steel wires to limit radial flexing and enhance lateral stiffness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If a relatively thick and heavy sidewall structure is used to render most of the sidewall radially rigid, then lateral stability is maintained, but weight increases and heat generation/rubber fatigue occurs due to concentrated deflection
Solution Approach 1:
The sidewall is segmented into three distinct regions: a radially-rigid inner conical surface, a radially-compliant outer conical surface, and a transition region connecting them. This segmentation allows each region to perform its specific function - the inner cone provides structural rigidity for lateral stability, the outer cone provides compliance for heat dissipation and flexibility, and the transition region manages the stress distribution between them.
Solution Approach 2:
Different regions of the sidewall are given different mechanical properties. The inner conical surface is made radially rigid to maintain lateral stability, while the outer conical surface is made radially compliant to allow flexion and heat dissipation. The transition region has intermediate properties to smoothly connect these two extremes and distribute stresses.
2Stability of the object's composition
If a relatively thick and heavy sidewall structure is used to render most of the sidewall radially rigid, then lateral stability is maintained, but the sidewall structure becomes more complex and material consumption increases
Solution Approach 1:
The sidewall is segmented into three distinct regions: a radially-rigid inner conical surface, a radially-compliant outer conical surface, and a transition region connecting them. This segmentation allows each region to perform its specific function - the inner cone provides structural rigidity for lateral stability, the outer cone provides compliance for heat dissipation and flexibility, and the transition region manages the stress distribution between them.
3Adaptability or versatility
If the sidewall is made flexible to allow radial deflection under vertical load, then vertical loading is accommodated, but lateral stability is reduced
Solution Approach 1:
Different regions of the sidewall are given different mechanical properties. The inner conical surface is made radially rigid to maintain lateral stability, while the outer conical surface is made radially compliant to allow flexion and heat dissipation. The transition region has intermediate properties to smoothly connect these two extremes and distribute stresses.
Solution Approach 2:
The sidewall geometry is changed from a conventional cylindrical shape to a V-shaped cross-section with inner and outer conical surfaces. This geometric transformation creates the anisotropic mechanical behavior where the sidewall is rigid in the lateral direction (due to the wedging effect between cones) but compliant in the vertical direction (allowing radial deflection through the transition region).
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 tire maintains stability and reduces extreme deformation by distributing vertical displacement across multiple angles, providing enhanced lateral stiffness and resistance to lateral forces, even under reduced air pressure, while allowing for radial mobility and accommodating vertical loading.
Implementation Method 1
the '676 publication employs radially-rigid inner and outer conical surfaces (130, 150) which generate a wedging ('valve lock-up') effect between them
Implementation Method 2
a radial reinforcing structure associated with the first portion of each of the sidewalls and configured to limit radial flexing of the first portion of the sidewall
Implementation Method 3
a girth-limiting configuration associated with the first portion of each of the sidewalls and encircling the tire axis
Data Source
AI summary
A pneumatic tire has a non-stretchable tread (30) flanked by two shoulder regions (34), and two non-stretchable bead regions (36) for mounting the tire to a wheel, each bead region being connected via a sidewall to the corresponding bead region. Each sidewall has a first portion (38) extending inwardly relative to a width of the tire from one of the bead regions (36) to a deflection region (40), and a second portion (42) extending outwardly relative to the width of the tire from the deflection region (40) to a corresponding one of the shoulder regions (34). A non-stretchable girth-limiting configuration (44, 46, 56) and a radial reinforcing structure (48, 50, 52) are associated with the first portion (38) of each of the sidewalls, thereby limiting radial flexing of first portion (38) and maintaining an annular concavity between the bead region (36) and the shoulder region (34).