Four-Layer Tyre Crown Reinforcement with Individual Wires
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Solution Overview
Problem
Current heavy-duty tires face challenges in maintaining endurance and wear performance under various conditions while minimizing mass and manufacturing costs, with existing solutions either compromising on endurance or increasing tire weight.
Innovation Solution
A tire design featuring four working crown layers with individual metal wires of reduced diameter and closer spacing, along with a layer of rubbery mixture to distribute shear stresses, maintains equivalent endurance and wear performance while reducing mass and manufacturing costs by optimizing crown reinforcement architecture.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the crown reinforcement uses thicker cables or more layers to improve endurance and wear performance, then the tire mass increases
Solution Approach 1:
The crown reinforcement is divided into four distinct working layers, each with specific functions. The first and second layers form a first triangulated reinforcement, the third and fourth layers form a second triangulated reinforcement. This segmentation allows optimized stress distribution across layers, improving endurance without requiring excessive thickness in any single layer, thus controlling overall tire mass.
Solution Approach 2:
The patent uses a combination of metallic cables with specific extensibility characteristics (some elastic with ≥3% elongation, some inextensible with ≤0.2% elongation) combined with rubber compound. This composite structure allows the reinforcement to withstand both elastic deformation and rigid load-bearing, achieving superior wear and endurance performance while maintaining reasonable mass through material optimization.
2Weight of moving object
If the reinforcing elements are spaced further apart to reduce mass, then the structural strength and crack resistance decrease
Solution Approach 1:
The patent transitions from traditional parallel cable arrangements to a triangulated reinforcement structure where cables in adjacent layers are crossed at angles of 10°-45° relative to the circumferential direction. This dimensional reconfiguration creates a three-dimensional stress distribution network that enhances crack resistance and structural strength even with reduced cable spacing, thereby reducing mass while maintaining strength.
Solution Approach 2:
The triangulated reinforcement structure is designed to preemptively resist crack propagation by creating intersecting stress paths before cracks can develop. The crossed cable arrangements in adjacent layers establish a pre-formed geometric pattern that intercepts and redistributes stress concentrations, preventing crack initiation and propagation while allowing larger spacing between individual cables.
3Reliability
If additional reinforcement layers are added to improve endurance, then the manufacturing complexity and cost increase
Solution Approach 1:
Each of the four working layers serves multiple functions: the first and third layers provide circumferential reinforcement, the second and fourth layers provide radial reinforcement, and collectively they form two triangulated reinforcement systems. This multi-functionality allows the structure to achieve superior endurance with a standardized four-layer configuration rather than requiring complex additional reinforcement systems, simplifying manufacturing while improving reliability.
4Force
If the cable diameter is increased to improve load-bearing capacity, then the tire mass and manufacturing cost increase
Solution Approach 1:
Instead of using fewer thick cables, the patent segments the load-bearing function across four thinner cable layers. Each layer carries a portion of the total load, and the triangulated arrangement distributes stress efficiently across all layers. This segmentation allows the use of thinner individual cables (reducing mass) while maintaining or improving overall load-bearing capacity through the collective strength of the multi-layer system.
Solution Approach 2:
The patent combines cables with different extensibility characteristics (elastic and inextensible) within the four-layer structure. This composite cable system optimizes load distribution where elastic cables accommodate deformation and inextensible cables provide rigid load-bearing support. This material differentiation allows thinner cable diameters to achieve equivalent or superior load-bearing capacity compared to thicker uniform cables, reducing tire mass.
Data Source
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Figure 2
AI summary
The invention relates to a tyre comprising a crown ply formed by four working crown layers of reinforcing elements. According to the invention, in a meridian plane, the thickness of the four layers, measured in the equatorial plane, is less than 5 mm; the reinforcing elements of the four layers 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; and the axial width of each of the four working crown layers is greater than 60% of the axial width of the tread.