Tyre Tread Cutouts and Zonal Rubber Moduli
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Solution Overview
Problem
Current heavy-duty tires face issues with wear regularity and rolling resistance, particularly when equipped with longitudinal and transverse cutouts featuring hidden hollows, which can lead to irregular wear patterns and increased fuel consumption.
Innovation Solution
A tire design with a radial carcass reinforcement incorporating a crown reinforcement structure, including at least two working crown layers with calendered rubber mixtures, a layer of circumferential reinforcing elements, and specific cutout configurations such as longitudinal and transverse cutouts with defined depth and width ratios, along with a layer of circumferential reinforcing elements to manage stress and deformation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If longitudinal and transverse cutouts with hidden hollows are introduced in the tread, then rolling resistance is reduced, but wear regularity deteriorates
Solution Approach 1:
The patent applies local quality by differentiating the properties of rubber mixtures in different zones of the tread. Specifically, it uses a first rubber mixture for the central part and a second rubber mixture for the lateral parts, with different moduli of elasticity. This local differentiation allows the central part to accommodate deformation from cutouts while maintaining wear regularity at the shoulders, thus resolving the contradiction between reduced rolling resistance and maintained wear regularity.
2Strength
If the modulus of elasticity of calendering rubber mixture is increased, then wear resistance is improved, but rolling resistance increases
Solution Approach 1:
The patent implements local quality by assigning different rubber mixture formulations to different radial zones of the tread. The central part uses a rubber mixture with higher modulus for wear resistance, while lateral parts use a different formulation optimized for flexibility and rolling resistance. This zonal approach allows simultaneous optimization of both wear resistance and rolling resistance that would be conflicting in a uniform structure.
Solution Approach 2:
The patent applies parameter changes by modifying the modulus of elasticity of rubber mixtures in different zones. By changing the physical-chemical parameters of the rubber compounds (different moduli: E1 for central part, E2 for lateral parts with E1 > E2), the patent achieves different mechanical behaviors in different zones, allowing the tread to simultaneously provide wear resistance where needed and flexibility where required for low rolling resistance.
Data Source
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Figure 2
Figure 3~4
AI summary
The invention relates to a tyre comprising a crown reinforcement formed by at least two working crown layers (41, 43) of reinforcing elements and at least one layer (42) of circumferential reinforcing elements. According to the invention, the tread includes at least one longitudinal notch (8) and at least one transverse notch (10), the depth of said at least one longitudinal notch and said at least one transverse notch, measured on a new tyre, being greater than or equal to 40% of the thickness of the tread. The ratio of the width of said longitudinal notches measured at the base thereof to the width of same measured at the surface of the tread is strictly greater than 1.2, while the ratio of the width of said at least one transverse notch measured at the base thereof to the width of same measured at the surface of the tread on a new tyre is strictly greater than 1. The tensile modulus of elasticity at 10% elongation of at least one skim coat of at least one working crown layer is greater than 9 MPa, and the maximum tan(δ) value, denoted tan(δ)max, of the at least one skim coat of at least one working crown layer is less than 0.100. Fig. 2