Tire Crown Reinforcement with Rubber Layer for Wear and Rolling Resistance
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Solution Overview
Problem
Current heavy-duty tires face issues with wear regularity and rolling resistance, particularly with oblique cutouts on the tread, leading to irregular wear patterns and increased fuel consumption due to inefficient stress distribution and cohesion of rubber mixtures.
Innovation Solution
A tire design featuring a radial carcass reinforcement with a crown reinforcement structure, including a layer of circumferential reinforcing elements and a rubber mixture layer between the working crown layers, with specific dimensions and properties to enhance stress distribution and cohesion, reducing shear stresses and improving wear regularity and rolling resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If oblique cutouts are introduced on the tread to improve water evacuation and grip, then tread performance is improved, but wear regularity deteriorates due to irregular stress distribution
Solution Approach 1:
A layer of rubbery compound is introduced as an intermediary element between the working crown layers, positioned to bridge the gap created by oblique cutouts. This intermediary layer distributes stresses more uniformly across the tread, preventing the irregular wear patterns that would otherwise result from the cutout geometry while preserving the water evacuation and grip benefits.
Solution Approach 2:
The tire crown reinforcement is constructed as a composite structure combining working crown layers with a rubbery compound layer having specific viscoelastic properties. This composite design allows the stiffer working layers to provide structural integrity while the more compliant rubbery layer absorbs and distributes shear stresses, maintaining wear regularity despite the presence of oblique cutouts.
2Reliability
If the crown reinforcement structure is strengthened to improve durability, then endurance is improved, but rolling resistance increases due to higher energy losses
Solution Approach 1:
The rubbery compound layer is designed with specific viscoelastic parameters - a loss factor tan(δ) less than 0.100 and modulus of elasticity between 5-20 MPa - that optimize the balance between durability and energy efficiency. These parameter selections ensure the layer provides sufficient reinforcement for endurance while minimizing hysteresis losses during deformation cycles, thereby reducing rolling resistance.
Solution Approach 2:
The rubbery compound layer is positioned specifically between the working crown layers where shear stresses are most critical, rather than uniformly throughout the entire tire structure. This localized application provides reinforcement exactly where needed for durability while minimizing the overall material volume and associated energy losses, thus reducing rolling resistance.
3Reliability
If a layer of rubbery compound is introduced between working crown layers to reduce shear stresses, then wear regularity is improved, but device complexity increases
Solution Approach 1:
The crown reinforcement is segmented into distinct functional layers: working crown layers for structural integrity and a separate rubbery compound layer for stress distribution. This segmentation allows each layer to be optimized for its specific function and simplifies the manufacturing process by enabling independent production and assembly of each layer, despite the increased functional complexity.
Solution Approach 2:
The rubbery compound layer uses specific parameter ranges (modulus of elasticity 5-20 MPa, loss factor tan(δ) < 0.100, thickness 2-10 mm) that balance performance benefits with manufacturing feasibility. These parameter selections ensure the layer provides adequate stress distribution to improve wear regularity while maintaining practical dimensions for production and assembly.
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 design achieves improved wear regularity and reduced rolling resistance, maintaining endurance and performance even after partial wear, contributing to lower fuel consumption and extended tire life.
Implementation Method 1
a layer C of rubber compound being disposed between at least the ends of said at least two working crown layers
Implementation Method 2
The loss factor tan(δ), noted tan(δ)max, of layer C is less than 0.100
Data Source
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AI summary
TIRE HAVING IMPROVED WEAR PROPERTIES AND IMPROVED ROLLING RESISTANCE The invention relates to a tire including a crown reinforcement formed of at least two working crown layers (41, 43) of reinforcing elements and at least one layer (42) of circumferential reinforcing elements, a layer C being placed between the ends of the working crown layers. In accordance with the invention, the tread has at least one diagonally oriented cut (7), the depth, measured on a new tire, of said at least one diagonally oriented cut being greater than or equal to 40% of the thickness of the tread, the ratio of the width measured at the bottom of said at least one diagonally oriented cut to the width measured on the surface of the tread of said at least one diagonally oriented cut being greater than 1.2, the tensile modulus of elasticity at 10% elongation of the layer C being greater than 9 MPa, and the maximum value of tan(8), denoted tan(8)max, of the layer C being less than 0.100. FIG. 2