Tyre with Low Sulfur Bridge Density in Crown Zones
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Solution Overview
Problem
Heavy-duty tires face endurance issues due to increased operating temperatures, leading to shear stresses and crack formation in the rubber at the ends of the crown reinforcement layers, which reduces the tire's lifespan and the effectiveness of elastomeric mixtures.
Innovation Solution
A tire design with a radial carcass reinforcement featuring a crown reinforcement comprising at least two working layers, where the relative density of sulfur bridges in specific zones is less than 5%, utilizing elastomeric mixtures based on diene elastomers like polybutadienes and isoprene copolymers, and a unique distribution of crosslinking densities to enhance resistance to temperature-induced aging.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional elastomeric mixtures with high sulfur content are used in the crown reinforcement zones, then the rubber provides good initial strength and bonding, but the endurance and resistance to temperature-induced aging deteriorate due to shear stresses and crack formation
Solution Approach 1:
The patent applies local quality by differentiating the sulfur content in different zones of the tire. Specifically, the elastomeric mixture in the crown reinforcement zones (where cracks typically form) has a reduced sulfur content (relative density of sulfur bridges less than 5%) compared to traditional formulations. This localized modification addresses the specific problem of temperature-induced aging and crack propagation in high-stress areas without compromising the overall tire performance.
Solution Approach 2:
The patent changes the chemical parameter of the elastomeric mixture by reducing the sulfur content and adjusting the crosslinking density. The relative density of sulfur bridges is controlled to be less than 5% in specific zones, which fundamentally alters the aging behavior and thermal resistance of the rubber in those areas, thereby improving endurance under high temperature conditions.
2Object-affected harmful factors
If the sulfur content in elastomeric mixtures is reduced to improve aging resistance, then the resistance to temperature-induced degradation improves, but the initial strength and bonding properties may deteriorate
Solution Approach 1:
The patent applies local quality by differentiating the sulfur content in different zones of the tire. Specifically, the elastomeric mixture in the crown reinforcement zones (where cracks typically form) has a reduced sulfur content (relative density of sulfur bridges less than 5%) compared to traditional formulations. This localized modification addresses the specific problem of temperature-induced aging and crack propagation in high-stress areas without compromising the overall tire performance.
Solution Approach 2:
The patent uses composite materials by combining elastomeric mixtures with different sulfur contents in different zones. The crown reinforcement zones use low-sulfur mixtures for aging resistance, while other zones may use traditional formulations, creating a composite structure that optimizes both initial strength and long-term durability.
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 reduced sensitivity to temperature-related aging, with enhanced resistance to degradation and increased mileage, while maintaining reduced hysteresis values for improved rolling resistance.
Implementation Method 1
the relative density of sulfur bridges measured according to the equilibrium swelling method being less than 5% in at least 30% of the elastomeric mixtures present in the surface of at least one zone S
Data Source
Figure 1
AI summary
The invention concerns a tyre having a radial carcass reinforcement (2), comprising a crown reinforcement (3) comprising at least two working crown layers of reinforcing elements, itself radially hooded by a tread layer (4), said tread layer being joined to two beads via two sidewalls. According to the invention, the relative density of sulfur bridges measured according to the equilibrium swelling method is less than 5% in at least 30% of the elastomeric mixtures present in the surface of at least one area S in a meridian plane, said elastomeric mixtures being compositions made from at least one diene elastomer chosen from the group of diene elastomers consisting of polybutadienes (abbreviated as "BR"), synthetic polyisoprenes (IR), natural rubber (NR), isoprene copolymers, butadiene copolymers with the exception of nitrile butadiene copolymers (NBR), excluding diene elastomers carrying carboxyl functions, and the mixtures of said diene elastomers.