Tire Tread Cutout Geometry and Rubber Layer Modulus
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Solution Overview
Problem
Current heavy-duty tires face issues with wear regularity in the transverse direction and increased rolling resistance due to longitudinal cutouts with hidden hollows, leading to irregular wear patterns and reduced fuel efficiency.
Innovation Solution
A tire design featuring a radial carcass reinforcement with a crown reinforcement comprising two working crown layers, a layer of rubber mixture between the layers, and a tread with longitudinal cutouts, where the depth of the cutouts is greater than 40% of the tread thickness and the ratio of the cutout width at the bottom to the surface width is greater than 2, along with a layer of circumferential reinforcing elements to manage shear stresses and maintain cohesion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If longitudinal cutouts with hidden hollows are introduced in the tread to improve grip performance, then grip performance is improved, but wear regularity deteriorates and rolling resistance increases
Solution Approach 1:
The patent specifies precise geometric parameters for the longitudinal cutouts: depth greater than 40% of tread thickness and width ratio (bottom width to surface width) greater than 2. These parameter optimizations balance grip performance with wear regularity and rolling resistance by controlling the deformation behavior of the tread during rolling
Solution Approach 2:
The cutouts are strategically positioned in the central part of the tread with specific dimensional characteristics that differ from other regions. This localized structural modification allows the central part to exhibit different mechanical properties compared to the axial outer parts, optimizing both grip and wear characteristics
2Loss of energy
If a layer of rubber mixture with low modulus of elasticity is used between working crown layers to reduce rolling resistance, then rolling resistance is reduced, but structural integrity may deteriorate
Solution Approach 1:
The rubber mixture layer is designed with specific mechanical properties: modulus of elasticity between 2 and 8 MPa and tan(δ) max less than 0.100. These parameter optimizations reduce hysteresis losses and rolling resistance while maintaining sufficient structural integrity through the controlled elastic response
Solution Approach 2:
The patent uses a composite rubber mixture composition containing specific elastomers (natural rubber, polyisoprene, polybutadiene, styrene-butadiene copolymer) in defined proportions, along with reinforcing fillers like carbon black and silica. This composite formulation achieves the desired balance between low rolling resistance and adequate strength
3Use of energy by moving object
If the modulus of elasticity of the rubber mixture layer is reduced to improve fuel efficiency, then fuel efficiency is improved, but wear regularity may deteriorate
Solution Approach 1:
The modulus of elasticity is optimized to a specific range (2-8 MPa) that minimizes energy losses during deformation while preventing irregular wear patterns. This parameter optimization ensures that the rubber mixture layer provides sufficient flexibility for fuel efficiency without compromising wear regularity
Solution Approach 2:
The tan(δ) max parameter serves as a feedback criterion to control the viscoelastic properties of the rubber mixture. By keeping tan(δ) max less than 0.100, the design ensures minimal energy dissipation as heat, directly improving fuel efficiency while maintaining stable wear characteristics
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
This design enhances wear regularity and reduces rolling resistance, contributing to improved fuel efficiency and extended tire life by controlling deformations and maintaining the structural integrity of the crown reinforcement during manufacturing and use.
Implementation Method 1
a layer C of rubber mixture being arranged between at least the ends of said at least two working crown layers, the modulus of elasticity under tension at 10% elongation of which is less than 8 MPa and the maximum value of tan(δ), denoted tan(δ) max, of which is less than 0.100
Implementation Method 2
the crown reinforcement comprising at least a layer of circumferential reinforcing elements
Implementation Method 3
said tread consisting of at least one central part extending to the less in the zone of the equatorial plane and two axially outer parts and having at least in said central part at least one cutout of longitudinal orientation, the depth, measured on a new tire in at least said central part, of said at least one cutout d longitudinal orientation being greater than or equal to 40% of the thickness of the tread
Data Source
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AI summary
The invention relates to a tire including a crown reinforcement consisting of at least two working crown plies (41, 43) of reinforcement elements, and at least one ply (42) of circumferential reinforcement elements, a ply C being arranged between the ends of the working crown plies. According to the invention, the tread has at least one longitudinal indentation (8), the depth, measured on a new tire, of said at least one longitudinal indentation being no less than 40% of the thickness of the tread, the ratio of the width measured at the bottom of said at least one longitudinal indentation to the width measured on the surface of the tread of said at least one longitudinal indentation being strictly greater than 2, and the modulus of elasticity under tension at 10% elongation of the ply C is less than 8 MPa, the maximum value of tan(8), denoted tan(8) max, of the ply C being less than 0.100. FIGURE 2