Tyre Tread Longitudinal Cutouts and Viscoelastic Skim Coats
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Solution Overview
Problem
Current heavy-duty tires face issues with wear regularity in the transverse direction and increased rolling resistance due to longitudinal cuts with hidden hollows, leading to irregular wear patterns and reduced fuel efficiency.
Innovation Solution
A tire design with a radial carcass reinforcement featuring a crown reinforcement comprising two working layers, a layer of circumferential reinforcing elements, and a tread with longitudinal cutouts that have a depth greater than 40% of the tread thickness and a width ratio at the bottom to surface width greater than 2, along with calendering layers having a modulus of elasticity under tension at 10% elongation less than 8.5 MPa and a maximum tan(δ) value less than 0.100.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If longitudinal cuts with hidden hollows are introduced in the tread, then rolling resistance is reduced, but wear regularity in the transverse direction deteriorates
Solution Approach 1:
The patent applies local quality by differentiating the cutout characteristics across different regions of the tread. The first longitudinal cuts have specific depth and width ratio characteristics, while the second longitudinal cuts have different characteristics. This regional differentiation allows the tread to achieve low rolling resistance in some areas while maintaining wear regularity in others, resolving the contradiction between energy efficiency and wear uniformity.
2Stability of the object's composition
If the depth of longitudinal cutouts is increased to improve wear patterns, then tread flexibility is improved, but structural integrity of the tread deteriorates
Solution Approach 1:
The patent employs parameter changes by precisely controlling the depth and width ratio parameters of the longitudinal cutouts. The first set of cuts has a depth between 0.4-0.6 times the tread thickness and a width ratio between 0.5-1.5, while the second set has different parameters. This parametric optimization ensures the cutouts provide sufficient flexibility for wear management while maintaining the structural integrity needed to support load-bearing functions.
3Strength
If circumferential reinforcing elements are added to enhance load capacity, then tire strength is improved, but device complexity increases
Solution Approach 1:
The patent applies composite materials by combining circumferential reinforcing elements with the tread structure. The reinforcing elements are integrated into the crown reinforcement layer, creating a composite structure that enhances load capacity. This composite approach allows the tire to achieve higher strength requirements while the reinforcing elements are strategically positioned to provide maximum benefit with minimal added complexity.
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
This design enhances wear regularity and reduces rolling resistance, maintaining satisfactory endurance properties and cohesion of the rubber mixture, thereby improving fuel efficiency and extending tire lifespan.
Implementation Method 1
the modulus of elasticity under tension at 10% elongation of at least one calendering layer of at least one working top layer being less than 8.5 MPa and the maximum value of tan(δ), denoted tan(δ)max, of said at least one calendering layer of at least one working top layer being less than 0.100
Implementation Method 2
said tread consisting of at least one central part extending at least in the area of the equatorial plane and two axially outer parts and having at least in said central part at least one cutout of longitudinal orientation, the depth, measured on a new tire in at least said central part, of said at least one cutout of longitudinal orientation being greater than or equal to 40% of the thickness of the tread
Implementation Method 3
a crown reinforcement formed of at least two working crown layers, each formed of reinforcing elements inserted between two layers of rubber mixture calendering, the crown reinforcement comprising at least one layer of circumferential reinforcing elements
Data Source
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AI summary
The invention relates to a tyre comprising a crown reinforcement made up of at least two working crown layers of reinforcing elements and of at least one layer of circumferential reinforcing elements. According to the invention, the tread includes at least one longitudinal notch, the depth of said at least one longitudinal notch, measured on a new tyre, being greater than or equal to 40% of the thickness of the tread, and the ratio of the width of said at least one longitudinal notch measured at the base thereof to the width of same measured at the surface of the tread is strictly greater than 2. 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 at least one skim coat of at least one working crown layer is less than 0.100.