Tire Design with Segmented Tread and Underlayer for Rolling Resistance
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Solution Overview
Problem
Current tire technologies face challenges in reducing rolling resistance while maintaining or improving other essential performance characteristics such as wear resistance, grip, and road behavior.
Innovation Solution
A tire design featuring a specific dimensioning as 'tall and narrow' with a special crown geometry and tread pattern, utilizing rubber compositions with controlled tan δ values and Shore A hardness, and a radial carcass reinforcement, along with an underlayer and tread design that satisfies specific diameter-to-width ratios and tread pattern characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If low-hysteresis materials are used to reduce rolling resistance, then energy consumption is reduced, but wear resistance and grip may deteriorate
Solution Approach 1:
The tire is divided into multiple functional zones with different rubber compositions: the tread uses low-hysteresis material for reduced rolling resistance, while the underlayer and shoulder regions use high-hysteresis material for enhanced grip and wear resistance. This segmentation allows each zone to optimize its performance independently.
Solution Approach 2:
Different regions of the tire are assigned different material properties: the central tread area uses soft, low-hysteresis compound for energy efficiency, while the shoulders and underlayer use harder, high-hysteresis compound for mechanical durability and wet surface grip. This local differentiation resolves the contradiction between rolling resistance and wear resistance.
2Loss of energy
If low-hysteresis materials are used to reduce rolling resistance, then energy consumption is reduced, but grip on wet surfaces may deteriorate
Solution Approach 1:
The tread is segmented into central and shoulder regions with different rubber compositions. The shoulder regions use high-hysteresis material that provides superior wet surface grip, while the central region uses low-hysteresis material for reduced rolling resistance.
Solution Approach 2:
High-hysteresis rubber composition is specifically applied to the underlayer and shoulder regions where wet surface contact occurs, providing local enhancement of grip performance without compromising the overall rolling resistance benefits of the low-hysteresis tread material.
3Loss of energy
If the tire mass is reduced by reducing material thicknesses and densities, then rolling resistance is reduced, but structural strength and durability may deteriorate
Solution Approach 1:
The tire uses composite construction with multiple rubber compositions having different properties: soft low-hysteresis material in the tread for rolling resistance, harder high-hysteresis material in the underlayer for structural support, and reinforced bead areas for durability. This composite approach achieves mass reduction while maintaining strength through strategic material placement.
Solution Approach 2:
Different material densities and thicknesses are applied locally: thinner, lighter material in the tread center for reduced rolling resistance, and thicker, denser material in the underlayer and bead regions for structural strength. This local differentiation maintains overall durability while reducing total mass.
4Quantity of substance
If the tire dimensions are reduced overall, then mass is reduced, but rolling resistance reduction may be limited and other performance characteristics may deteriorate
Solution Approach 1:
Instead of uniformly reducing all dimensions, the invention changes specific parameters: using low-hysteresis material in the tread, optimizing the tread pattern geometry, and adjusting the underlayer thickness to 20-40% of tread thickness. These parameter changes achieve rolling resistance reduction and mass reduction simultaneously without compromising 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
This design achieves reduced rolling resistance while enhancing wear resistance and grip, particularly on wet surfaces, and improving cornering stiffness, as demonstrated by comparative calculations and tests.
Implementation Method 1
the tread is made from at least one first rubber composition having a maximum value of tan δ at 23° C. and 10 Hz, determined by scanning the shear strain rate, greater than or equal to 0.1 and less than or equal to 0.4, and a Shore A hardness that is greater than or equal to 55 and less than or equal to 65
Implementation Method 2
the maximum value of tan δ at 23° C. and 10 Hz, determined by scanning the shear strain rate, of this second rubber composition being less than that of the said at least one first rubber composition from which the tread is made
Implementation Method 3
the average depth of the tread pattern, in an axial zone of the tread having a width equal to two thirds of the axial width of the tread and being centred about the median plane, is greater than or equal to 4.5 mm and less than or equal to 7 mm, and is preferably less than or equal to 6.5 mm, and the voluminal cavity ratio of the tread pattern is greater than or equal to 15% and less than or equal to 25%
Implementation Method 4
at least one radial carcass reinforcement extending from the beads across the sidewalls as far as the crown. The tire has an outer diameter OD and a nominal section width SW
Implementation Method 5
two beads intended to enter into contact with a mounting rim, each bead comprising at least one annular reinforcement structure defining a median plane perpendicular to the axis of rotation of the tire
Implementation Method 6
an under layer extending over the whole of the axial width of the tread and arranged radially between the tread and the crown reinforcement, the average radial height of the under layer being greater than or equal to 20% of the average radial height of the tread, the under layer being made from a second rubber composition, the maximum value of tan δ at 23° C. and 10 Hz, determined by scanning the shear strain rate, of this second rubber composition being less than that of the said at least one first rubber composition
Data Source
AI summary
Tire having a load index LI, as defined in the ETRTO Standards Manual 2010, lying in the range between 65 and 105. The tire comprises a tread and an under layer (48) extending over the whole width of the tread and having an average radial height greater than 20% of the average radial height of the tread and a maximum value of tan δ at 23° C. and 10 Hz less than the corresponding value of the tread. Radial carcass reinforcement (60) extends from the beads across the sidewalls as far as the crown. The tire has an outside diameter OD and a nominal section width SW, as defined in the ETRTO Standards Manual 2010, that satisfy the following inequality: OD/SW>−0.00082641 LI2+0.11266 LI−0.185.