Pneumatic Tire Bead Area Dual-Layer Rubber Structure
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Solution Overview
Problem
Tubeless pneumatic tires face challenges in maintaining effective sealing and resisting damage during mounting and dismounting, particularly at the bead area where the tire meets the rim, due to inadequate sealing and stress concentrations.
Innovation Solution
The implementation of a dual-layer rubber structure within the bead area, where a first layer with lower modulus of elongation provides tackiness and a second layer with higher modulus of elongation offers enhanced rigidity and tear resistance, extending across the full width of the bead ring to distribute stress and prevent damage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a single-layer rubber structure is used in the bead area, then the structure is simple and easy to manufacture, but the resistance to mounting and dismounting damage is insufficient and stress concentrations occur
Solution Approach 1:
The bead area rubber structure is segmented into two distinct layers: a first layer with lower modulus of elongation and a second layer with higher modulus of elongation. This segmentation allows each layer to perform its specific function - the first layer provides flexibility and stress distribution while the second layer provides tear resistance and structural integrity, thereby improving overall damage resistance without excessive complexity
Solution Approach 2:
The invention uses composite material construction by combining two rubber materials with different modulus of elongation properties in the bead area. This composite structure leverages the complementary strengths of each material - the softer first layer for stress distribution and the stiffer second layer for tear resistance - achieving superior performance compared to single-material constructions
2Strength
If the rubber material has high modulus of elongation throughout, then tear resistance is improved, but stress-strain concentrations occur during mounting and dismounting
Solution Approach 1:
The invention applies local quality by giving different regions of the bead area different material properties. The first layer with lower modulus of elongation is positioned to absorb and distribute mounting stresses, while the second layer with higher modulus of elongation is positioned to provide tear resistance where needed, optimizing both stress distribution and tear resistance locally
3Reliability
If the sealing portion is made more rigid to maintain sealing, then sealing capability is improved, but resistance to mounting damage decreases
Solution Approach 1:
The invention changes the material parameter (modulus of elongation) across different layers of the sealing portion. The first layer uses rubber material with a lower modulus of elongation to provide flexibility and resistance to mounting damage, while the second layer uses rubber material with a higher modulus of elongation to maintain sealing capability, achieving both objectives through parameter variation
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
This configuration improves the tire's resistance to mounting and dismounting damage by reducing stress-strain concentrations and maintaining effective sealing, ensuring better retention of the pressurized inflation atmosphere and increased durability.
Implementation Method 1
a first layer of rubber material is arranged radially inward from both the bead ring radial inner side and the carcass ply
Implementation Method 2
the carcass ply comprising an array of reinforcements arranged within a matrix of elastomeric material
Data Source
AI summary
A pneumatic tire having a pair of annular bead areas (12), a pair of sidewalls, and a crown portion wherein a carcass ply (22) wraps around a radial inner side (RSj,2o) of each bead ring (20), for each bead area (12) a first layer of rubber material (30) is arranged radially inward from both the bead ring radial inner side (RSi,2o) and the carcass ply (22) and a second layer of rubber material (40) is arranged radially inward from the first layer of rubber material (30), each of the first layer of rubber material (30) and the second layer of rubber material (40) extending substantially across a full width (W20) of the corresponding bead ring (20), each of the first and second layer of rubber material (30, 40) having a modulus of elongation, where the modulus of elongation of the second layer of rubber material (40) is equal to or greater than substantially 125% of the modulus of elongation of the first layer of rubber material (30).