Tire Crown Reinforcement with Circumferential Elements
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Solution Overview
Problem
Heavy-duty tires face endurance and wear issues due to shear stresses and temperature increases at the ends of the crown reinforcement, leading to cracking and reduced mileage, despite existing solutions that improve performance but not consistently across all conditions.
Innovation Solution
A tire design with a radial carcass reinforcement featuring working crown layers with specific skim coats of elastomeric mixtures and a layer of circumferential reinforcing elements, which reduces shear stresses and temperature increases, maintaining endurance and wear performance while improving rolling resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If a layer of circumferential reinforcing elements is added to improve rolling resistance, then fuel efficiency is improved, but the complexity of the tire structure increases
Solution Approach 1:
The circumferential reinforcing elements are integrated within the existing crown reinforcement structure, nesting the new functional layer between the working crown layers. This allows the tire to gain improved rolling resistance characteristics while maintaining a compact, organized structure that does not significantly increase overall complexity.
Solution Approach 2:
The circumferential reinforcing elements serve multiple functions: they reduce rolling resistance to improve fuel efficiency, provide additional structural support, and work synergistically with the diagonal crown layers to distribute stresses. This multi-functionality justifies the added structural element.
2Productivity
If the tire is designed for high speed and long distance travel, then productivity is improved, but the endurance of the crown reinforcement deteriorates due to shear stresses and temperature increases
Solution Approach 1:
The crown reinforcement is divided into distinct functional layers: working crown layers for primary load bearing, circumferential reinforcing elements for stress distribution, and protective layers for durability. This segmentation allows each layer to be optimized for its specific function, improving overall endurance under high-speed, long-distance conditions.
Solution Approach 2:
The circumferential reinforcing elements act as intermediary components between the working crown layers and the protective layers. They mediate the transmission of stresses, distributing shear forces and reducing temperature increases by providing an additional thermal and mechanical buffer zone, thereby protecting the crown reinforcement from degradation.
3Strength
If the skim coat uses elastomeric mixture with high tensile modulus to reduce deformation, then strength is improved, but the loss factor increases leading to higher rolling resistance
Solution Approach 1:
The patent optimizes the parameters of the elastomeric mixture in the skim coat, specifically adjusting the tensile modulus to a range that provides sufficient strength while controlling the loss factor. By carefully selecting and balancing the compositional parameters, the design achieves an optimal trade-off between strength and energy loss, preventing excessive rolling resistance.
Solution Approach 2:
The skim coat is designed with specific local properties at the crown layer interface, using elastomeric mixtures with tailored mechanical characteristics. This localized optimization ensures that the area most subject to stress and deformation has the appropriate balance of strength and flexibility, minimizing energy losses while maintaining structural integrity.
Data Source
AI summary
A tire comprising a crown reinforcement formed from at least two working crown layers of reinforcing elements and at least one layer of circumferential reinforcing elements, wherein, the tensile modulus of elasticity at 10% elongation of at least one skim coat of at least one working crown layer is greater than 9 MPa and the maximum value of tan(δ), denoted tan(δ)max, of said skim coat is less than 0.100.