Multi-Material Tire Tread Sub-Layer for Rolling Resistance Balance
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Solution Overview
Problem
Current tire designs face a trade-off between dynamic drift thrust response and rolling resistance, where improving one often worsens the other, and existing sub-layer materials struggle to achieve a balance of performance properties.
Innovation Solution
A tire design featuring a sub-layer with a base layer and a covering layer of specific rubber compounds, where the stiffness of the base layer is less than the covering layer, and both are distinct from the tread, optimizing the dynamic shear modulus and tangent delta values to enhance cornering stiffness while minimizing rolling resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If sub-layer material with low dynamic shear modulus is used to minimize rolling resistance, then rolling resistance is reduced, but cornering stiffness deteriorates
Solution Approach 1:
The sub-layer is divided into multiple layers with different rubber compounds having different dynamic shear moduli. The first sub-layer (adjacent to crown reinforcement) has lower modulus for low rolling resistance, while the second sub-layer (adjacent to tread) has higher modulus for adequate cornering stiffness. This segmentation allows each layer to perform its specific function independently.
Solution Approach 2:
Different regions of the sub-layer are assigned different material properties. The first sub-layer uses a rubber compound with dynamic shear modulus of 0.5-2.0 MPa optimized for energy efficiency, while the second sub-layer uses a compound with dynamic shear modulus of 2.0-5.0 MPa optimized for mechanical strength and cornering performance. Each local region has quality tailored to its functional requirements.
2Strength
If sub-layer material with high dynamic shear modulus is used to improve cornering stiffness, then cornering stiffness is improved, but rolling resistance increases
Solution Approach 1:
The sub-layer is segmented into two functional layers. The second sub-layer (higher modulus) is positioned where cornering stiffness is needed, while the first sub-layer (lower modulus) is positioned where low rolling resistance is prioritized. This segmentation allows high stiffness only where mechanically necessary.
Solution Approach 2:
High dynamic shear modulus material is applied locally in the second sub-layer where cornering stiffness is required, rather than uniformly throughout the entire sub-layer. This local quality approach minimizes the volume of high-modulus material, thereby reducing overall hysteresis and rolling resistance while maintaining adequate cornering performance.
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
The design achieves a significant improvement in rolling resistance with only a modest reduction in cornering stiffness, providing better dynamic response and handling performance, suitable for passenger vehicles.
Implementation Method 1
sub-layer materials under the tread are used to improve the rolling resistance of the tire with a material of low hysteresis
Implementation Method 2
the dynamic shear modulus G* of the material of the base layer, measured at 23° C. and under an alternating shear stress at a frequency of 10 Hz and at 10% deformation
Data Source
AI summary
Tire (1) having a sub-layer (7) made up substantially of a base layer (71) disposed radially on the crown reinforcement (5) and axially between the median plane (CP) and a shoulder (60), said base layer (71) being made up of a rubber compound of given stiffness A, a covering layer (72) disposed radially on the base layer (71) and radially on the inside of the tread (6) and axially at least in sections situated between the median plane (CP) and the shoulder end (721), said covering layer (72) being made up of a rubber compound of given stiffness B, the stiffness A being less than the stiffness B, and the stiffness B being greater than the stiffness M.