Tire Crown Reinforcement Angles for Stony-Ground Endurance
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Solution Overview
Problem
Heavy-duty tires face challenges in endurance when driving on stony ground due to increased operating temperatures leading to cracks and reduced performance, while existing solutions to enhance endurance either increase tire mass or manufacturing costs.
Innovation Solution
A tire design with a radial carcass reinforcement featuring two working crown layers with angles greater than 8° relative to the circumferential direction, combined with a circumferential reinforcing element layer, optimized to reduce stress and maintain lightweight construction by adjusting the angles and layer configurations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If additional layers of reinforcing elements are added to improve endurance, then the tire's resistance to cracking and corrosion improves, but the tire mass increases
Solution Approach 1:
The patent removes the protective layer of circumferential reinforcing elements from the crown reinforcement structure, retaining only the two working crown layers. This extraction eliminates unnecessary mass while preserving the essential load-bearing and stress-distributing functions, thereby improving the reliability-to-weight ratio without compromising endurance performance.
Solution Approach 2:
The patent optimizes the angular parameters of the working crown layers, specifying that they form angles between 10° and 45° with the circumferential direction. By carefully selecting these angular parameters, the design achieves effective stress distribution and resistance to cracking without requiring additional protective layers, thus maintaining lightweight construction while ensuring durability.
2Reliability
If the number of reinforcing layers is increased to improve shock resistance, then the tire's durability against impacts improves, but the manufacturing cost increases
Solution Approach 1:
The patent eliminates the protective layer of circumferential reinforcing elements, simplifying the crown reinforcement structure to essentially two working crown layers. This reduction in the number of layers directly lowers manufacturing complexity and cost while maintaining sufficient durability through optimized angular configuration and material properties of the remaining layers.
Solution Approach 2:
The patent employs composite material strategies by using steel cords or steel wire strands with specific construction configurations (e.g., 7x7, 19x7 constructions) and optimal angular arrangements. This allows the two working crown layers to achieve composite-like performance that provides shock resistance and durability equivalent to or exceeding traditional multi-layer designs, thereby reducing manufacturing costs.
3Reliability
If operating temperature is reduced to prevent cracking, then the tire's resistance to crack propagation improves, but the tire's performance under heavy loads decreases
Solution Approach 1:
The patent specifies that the working crown layers form angles between 10° and 45° with the circumferential direction, with at least one layer forming an angle greater than 20°. This angular parameter optimization enables effective stress distribution that reduces thermal stress concentrations and crack propagation risk, while simultaneously maintaining load-bearing capacity through the geometric configuration of the reinforcing elements.
Solution Approach 2:
The patent uses steel cords or steel wire strands with specific constructions (e.g., 7x7, 19x7) that provide both thermal stability and mechanical strength. The composite structure of these reinforcing elements, combined with optimized angular arrangement, creates a crown reinforcement system that resists cracking under thermal stress while maintaining high load-bearing capacity for heavy-duty applications.
Data Source
Figure 1
AI summary
The invention relates to a pneumatic tire comprising a crown reinforcement (4) made up of two working crown plies (41, 42) of reinforcing elements and at least one ply (43) of circumferential reinforcing elements. According to the invention, the two working crown plies (41, 42) and the at least one ply of circumferential reinforcing elements (43) exclusively form the crown reinforcement (4) over at least 80 % of the width of the tread (5), the absolute value of the difference between the absolute values of the angles ᾳ2 et ᾳ1 is greater than 4°, the absolute value of ᾳ2 is greater than that of ᾳ1, the mean angle ᾳ satisfies the relation 14+131 * exp(-L/100) < ᾳ < 28+110 * exp(-L/100), and the ratio (R=(dC-dE)/dS) is such that 0.05< R < 3.