Tire Crown Reinforcement with Circumferential Elements
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Solution Overview
Problem
Current heavy-duty tires face challenges in maintaining endurance and wear resistance, especially under high-speed and long-distance conditions, due to shear stresses and increased operating temperatures, which lead to cracks and reduced performance.
Innovation Solution
A tire design featuring a radial carcass reinforcement with a crown reinforcement structure that includes a first layer of rubber compound with a low elastic modulus and high dispersion coefficient, a second layer of polymer compound extending to the tread, and circumferential reinforcing elements, which decouples shear stresses and enhances cohesion and cornering stiffness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional crown reinforcement structure is used, then load bearing capacity is maintained, but shear stresses cause cracks and reduce endurance under high-speed conditions
Solution Approach 1:
The crown reinforcement is divided into multiple layers with different orientations: working layers (10-45°), triangulation layer (45-90°), and circumferential layer (≤2.5°). This segmentation allows each layer to specifically address different stress components, with the circumferential layer specifically targeting shear stress reduction to improve endurance
Solution Approach 2:
The patent uses composite reinforcement structures combining different types of cords (metallic and textile) and different layer orientations. The triangulation layer uses inextensible cords at high angles to form a triangulated reinforcement that resists shear forces, while working layers use extensible cords for load bearing, creating a composite system that maintains strength while reducing shear-induced cracking
2Productivity
If high-speed operation is maintained, then productivity increases, but operating temperature rises causing crack formation
Solution Approach 1:
The crown is segmented into multiple functional layers that distribute thermal and mechanical stresses. The triangulation layer with inextensible cords provides thermal stability and crack resistance, while the working layers handle dynamic loads, allowing high-speed operation without temperature-induced cracking
Solution Approach 2:
The triangulation layer acts as a preventive measure against thermal cracking by providing a stable, heat-resistant framework before thermal damage occurs. This layer cushions against the harmful effects of high operating temperatures that result from high-speed operation
3Loss of energy
If circumferential reinforcing elements are added, then rolling resistance and fuel consumption are improved, but device complexity increases
Solution Approach 1:
The crown is divided into specialized layers including a circumferential layer with cords oriented at ≤2.5° to the circumferential direction. This segmentation reduces rolling resistance by optimizing cord orientation for minimal deformation, while the modular layer structure makes the complexity manageable through clear functional differentiation
Solution Approach 2:
The circumferential layer uses cords with specific orientation parameters (≤2.5° angle) and specific material properties (extensibility ≥3%) to optimize rolling resistance. By changing the orientation parameter of this specific layer while maintaining other layers' parameters, energy loss is reduced without requiring complete redesign of the entire reinforcement system
Data Source
AI summary
Tire comprising a crown reinforcement formed of at least two working crown layers of reinforcing elements. First layer C of rubber compound is placed between ends of the two working crown layers. Second layer S of polymer compound is in contact with at least one working crown layer and with the carcass reinforcement. The crown reinforcement includes at least one layer of circumferential reinforcing elements. The elastic modulus under tension at 10% elongation of first layer C is less than 8 MPa, the maximum value of tan(δ) of first layer C is less than 0.100. The second layer S is made up of a filled elastomer blend having a macro dispersion coefficient Z greater than or equal to 65 and a maximum tan(δ) value less than 0.100, and its complex dynamic shear modulus G*, measured at 10% and 60° C. on the return cycle, is greater than 1.35 MPa.