Tyre Bead Elastomer Mixtures for Thermal Degradation Resistance
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Solution Overview
Problem
Heavy-duty tires face challenges in endurance under excessive loads and inflation pressures, leading to damage such as cracking in the bead area due to insufficient protection of the carcass reinforcement.
Innovation Solution
A tire design with a radial carcass reinforcement featuring a crown reinforcement and bead areas with specific elastomeric mixtures having a relative sulfur bridge density less than 5% in defined zones, combined with reinforcing elements oriented at angles less than 45°, provides enhanced protection and resistance to deformation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional elastomeric mixtures with high sulfur bridge density are used in the bead area, then the tire provides adequate protection against mechanical damage during assembly and disassembly, but the tire exhibits cracking and premature wear under excessive loads and inflation pressures due to insufficient resistance to temperature rises
Solution Approach 1:
The patent applies different elastomeric compositions to different zones of the tire bead area. Specifically, the first and second elastomeric mixtures with low sulfur bridge density (less than 5%) are used in zones subject to high temperature rises (near the carcass reinforcement and stiffening elements), while traditional mixtures may be used in other areas. This local differentiation allows the tire to resist thermal degradation in critical zones without compromising overall structural integrity.
Solution Approach 2:
The patent fundamentally changes the chemical composition parameters of the elastomeric mixtures by reducing sulfur bridge density to less than 5% in specific zones. This parameter change transforms the material's thermal stability and resistance to temperature-induced cracking, enabling the tire to withstand excessive loads and inflation pressures that generate high temperatures in the bead area.
2Strength
If the carcass reinforcement is anchored by turning around a rod in the bead area, then the tire structure gains strength and stability, but the elastomeric mixtures in this area are susceptible to cracking and damage under excessive use conditions
Solution Approach 1:
The patent applies elastomeric mixtures with specific low sulfur bridge density characteristics specifically in the zones adjacent to the carcass reinforcement and stiffening elements in the bead area. This localized application ensures that the most vulnerable regions (where cracking typically occurs under excessive use) are protected by material with superior resistance to thermal and mechanical degradation.
Solution Approach 2:
The patent uses composite elastomeric formulations combining specific polymers (such as polybutadiene, synthetic polyisoprene, or natural rubber) with controlled sulfur content and complementary additives. These composite materials provide both the structural compatibility needed for carcass reinforcement anchoring and the enhanced durability required to resist cracking under excessive loads and inflation pressures.
3Ease of manufacture
If traditional elastomeric mixtures are used throughout the tire, then the manufacturing process is simple and cost-effective, but the tire shows premature wear and reduced endurance in the bead area under heavy-duty conditions
Solution Approach 1:
The patent implements a zoned approach where elastomeric mixtures with low sulfur bridge density are applied only in specific critical zones (defined by radial and axial dimensions around the bead area), while other areas may use conventional mixtures. This selective application maintains manufacturing simplicity through targeted material placement rather than complete redesign of the entire tire structure.
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 exhibits improved endurance and resistance to aging, particularly during excessive use, with reduced sensitivity to temperature rises and improved rolling resistance, leading to extended tire life and performance.
Implementation Method 1
The tire exhibits improved endurance and resistance to aging, particularly during excessive use, with reduced sensitivity to temperature rises
Implementation Method 2
reduced sensitivity to temperature rises and improved rolling resistance, leading to extended tire life and performance
Implementation Method 3
provides enhanced protection and resistance to deformation
Implementation Method 4
the carcass reinforcement being anchored in each of the beads by turning around a rod
Data Source
Figure 1
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AI summary
The invention relates to a tyre having radial carcass reinforcement (2) consisting of a layer of reinforcing elements anchored in each of the beads by turning up around a bead wire (4), said turn-up of the carcass reinforcement being reinforced by at least one layer of reinforcing or stiffening elements (8). According to the invention, the relative density of sulphur bonds measured according to the method for inflation to equilibrium is lower than 5 % in at least 30 % of the elastomer mixtures contained in the surface of at least one area Z in a meridian plane, said elastomer mixtures being compositions based on at least one diene elastomer selected from the group of the diene elastomers consisting of the polybutadienes (in the abstract "BR"), the synthetic polyisoprenes (IR), natural rubber (NR), isoprene copolymers, butadiene copolymers except for the butadiene-nitrile copolymers (NBR), excluding the diene elastomers having carboxyl functions, and the mixtures of said diene elastomers.