Tyre Crown Reinforcement with Thin Metal Wires
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Solution Overview
Problem
Heavy-duty tires face challenges in maintaining endurance and wear performance under varying road conditions, with increased rolling resistance leading to higher fuel consumption, and existing solutions often result in increased tire mass and manufacturing costs.
Innovation Solution
A tire design with a radial carcass reinforcement featuring at least three working crown layers of unitary metal wires with specific dimensions and elasticity properties, along with a reduced distance between reinforcing elements, to maintain endurance while reducing mass and rolling resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If traditional heavy-duty tire crown reinforcement is used with thick working layers and widely spaced cables, then the tire has sufficient strength and durability, but the tire mass increases and rolling resistance increases leading to higher fuel consumption
Solution Approach 1:
The patent changes the physical parameters of the reinforcing elements by using unitary metal wires with diameter less than 0.50 mm (typically 0.15-0.40 mm) instead of traditional thicker cables, and reduces the distance between elements to less than 1 mm (typically 0.3-0.8 mm). These parameter changes maintain the required strength while reducing the overall mass of the tire.
Solution Approach 2:
The patent uses composite construction combining multiple materials: unitary metal wires (steel or other alloys) embedded in rubber calendering layers. This composite structure provides both the mechanical strength of metal and the flexibility and damping of rubber, achieving high strength-to-weight ratio.
2Weight of moving object
If traditional tire design with fewer working layers and larger distance between reinforcing elements is used, then the tire mass is lower, but the endurance and wear performance deteriorate under heavy loads and high speeds
Solution Approach 1:
The patent divides the crown reinforcement into at least three separate working layers instead of using fewer thicker layers. Each layer contains unitary metal wires spaced closely together. This segmentation distributes the mechanical loads more evenly across multiple layers, improving durability and wear resistance while keeping each individual layer thin and lightweight.
Solution Approach 2:
The patent applies different properties to different parts of the reinforcement structure: unitary metal wires provide localized high-strength points spaced closely (less than 1 mm apart) throughout each layer, while the rubber calendering layers provide matrix support and flexibility. This local quality optimization ensures strength where needed while minimizing overall mass.
3Strength
If traditional calendering layers with high elastic modulus are used, then the structural rigidity is sufficient, but the rolling resistance increases and fuel consumption increases
Solution Approach 1:
The patent changes the elastic modulus parameter of the calendering layers by selecting rubber compounds with lower elastic modulus (softer rubber) compared to traditional designs. This parameter change reduces the energy losses during deformation cycles, thereby reducing rolling resistance and fuel consumption, while the closely spaced unitary metal wires compensate for the reduced rubber stiffness to maintain sufficient structural rigidity.
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 equivalent endurance and wear performance with reduced tire mass and manufacturing costs, improved rolling resistance, and enhanced circumferential rigidity, leading to potential fuel savings and extended tire lifespan.
Implementation Method 1
the modulus of elasticity under tension at 10% elongation of at least one layer of calendering of at least one layer of working crown is less than 8.5 MPa
Implementation Method 2
the maximum value of tan(δ), denoted tan(δ) max, of said at least one calendering layer of at least one top layer working pressure is less than 0.100
Data Source
Figure 1
Figure 2
AI summary
The invention relates to a tyre comprising a crown ply formed by at least three working crown layers of reinforcing elements. According to the invention, in a meridian plane, the thickness of the layers, measured in the equatorial plane, is less than 5 mm; the reinforcing elements are individual metal wires having a diameter of less than 0.50 mm; the distance between the reinforcing elements, measured along the normal to the direction of the centre line of the wire, is strictly less than 1 mm; the axial width of each of the layers is greater than 60% of the axial width of the tread; the tensile modulus of elasticity at 10% elongation of at least one skim coat of at least one working crown layer is less than 8.5 MPa; and the maximum tan(δ) value, denoted tan(δ)max, of the skim coat is less than 0.100.