Tyre Carcass Reinforcement with High Resistivity Elastomer
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Solution Overview
Problem
Heavy-duty tires face endurance issues due to 'fatigue-fretting' and 'fatigue-corrosion' phenomena, leading to reduced lifespan and increased manufacturing costs, particularly under severe driving conditions.
Innovation Solution
A tire design with a radial carcass reinforcement featuring a layer of metallic elements between elastomeric mixture calendering layers, utilizing carbon black as a reinforcing filler with specific elastic modulus and electrical resistivity properties to minimize corrosion and heat generation, thereby enhancing endurance without increasing costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the thickness of the rubber layer is increased to improve airtightness and reduce corrosion, then the durability of the carcass reinforcement is improved, but the manufacturing cost increases
Solution Approach 1:
The invention changes the electrical resistivity parameter of the rubber compound from conventional values (log(ρ) < 8) to high resistivity values (log(ρ) ≥ 8). This parameter change allows the rubber layer to act as an electrical barrier, preventing electrochemical corrosion of the metallic reinforcement even at reduced thickness, thereby maintaining durability while reducing manufacturing costs.
Solution Approach 2:
The invention uses a composite rubber compound combining specific elastomers (natural rubber, polyisoprene, or synthetic diene elastomers) with carbon black filler in optimized proportions. This composite material provides both the mechanical properties needed for structural integrity and the high electrical resistivity (log(ρ) ≥ 8) required to prevent corrosion, eliminating the need for thicker rubber layers.
2Duration of action of moving object
If smaller diameter wires are used in carcass reinforcement cables to improve flexibility and bending endurance, then the flexibility and bending resistance are improved, but the cables become more permeable to corrosive agents
Solution Approach 1:
The invention introduces a high electrical resistivity rubber compound as an intermediary barrier between the metallic reinforcement cables and the external environment. This intermediary layer with log(ρ) ≥ 8 blocks the passage of corrosive agents through the cable structure, protecting the smaller diameter wires that provide flexibility and bending endurance.
Solution Approach 2:
The invention changes the electrical resistivity parameter of the protective rubber layer to high values (log(ρ) ≥ 8), which fundamentally alters its barrier properties. This parameter change enables the rubber to effectively block corrosive agents even when the cable structure itself remains permeable, allowing the use of smaller diameter wires for improved flexibility.
3Ease of manufacture
If conventional rubber compounds are used in calendering layers, then the manufacturing process is simple and cost-effective, but the cables are susceptible to fatigue-fretting-corrosion under severe driving conditions
Solution Approach 1:
The invention modifies the electrical resistivity parameter of the rubber compound from conventional levels (log(ρ) < 8) to high resistivity levels (log(ρ) ≥ 8). This single parameter change transforms the rubber's protective function, enabling it to prevent electrochemical corrosion without complicating the manufacturing process or significantly increasing costs.
Solution Approach 2:
The invention applies high electrical resistivity specifically to the calendering layers that are in direct contact with the metallic reinforcement cables. This localized quality enhancement provides targeted corrosion protection where it is most needed, while maintaining conventional rubber properties in other tire components where high resistivity is not required.
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 manufacturing costs by limiting corrosion and heat in stressed areas, maintaining performance across various driving conditions.
Implementation Method 1
at least said calendered layer closest to the internal cavity of at least the frame reinforcement layer closest to the internal cavity having a volume electrical resistivity ρ such that log(ρ) is greater than 8
Implementation Method 2
the modulus of elasticity under tension at 10% elongation of at least the calendered layer closest to the internal cavity of at least the carcass reinforcement layer closest to the internal cavity being less than 8,5 MPa
Data Source
Figure 1
AI summary
The invention relates to a tyre having a radial carcass reinforcement, consisting of at least one layer of metal reinforcing elements inserted between two calendering layers of an elastomeric compound comprising a reinforcing filler consisting of at least carbon black. According to the invention, the tensile modulus of elasticity at 10% elongation of at least the calendering layer closest to the inner cavity of at least the carcass reinforcement layer closest to the inner cavity is less than 8.5 MPa, and at least said calendering layer closest to the inner cavity of at least the carcass reinforcement layer closest to the inner cavity has an electrical resistivity per unit volume ρ such that log(ρ) is greater than 8.