Pneumatic Tire Tread Layout for Rolling Resistance and Durability
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Solution Overview
Problem
Existing pneumatic tires face a challenge in reducing rolling resistance while maintaining tire durability performance.
Innovation Solution
A pneumatic tire design featuring a carcass layer, cross belts, a layered tread rubber with a cap tread and undertread, and specific groove and land portion configurations, where the undertread in the center land portion has a low loss tangent and thick maximum gauge, and the undertread in the shoulder land portion has a thin maximum gauge, optimizing heat dissipation and durability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the undertread gauge is increased to suppress heat build-up and reduce rolling resistance, then tire rolling resistance performance is improved, but the cap tread gauge available for durability is reduced
Solution Approach 1:
The patent applies local quality by differentiating the undertread gauge across different tread regions. Specifically, the center land portion has a larger undertread gauge (0.15≤UT_ce/Ga_ce<0.30) to suppress heat build-up and reduce rolling resistance, while the shoulder land portion has a smaller undertread gauge (0.05≤UT_sh/Ga_sh<0.15) to preserve cap tread gauge for durability. This spatial differentiation of material properties resolves the contradiction between rolling resistance and durability.
2Reliability
If the undertread gauge is decreased in the shoulder land portion to preserve cap tread gauge for durability, then tire durability is improved, but heat build-up suppression capability is reduced
Solution Approach 1:
The patent addresses this contradiction by locally optimizing the undertread gauge for each region's specific functional requirements. The shoulder land portion uses a smaller undertread gauge ratio (0.05≤UT_sh/Ga_sh<0.15) to preserve cap tread material for durability, while the center land portion uses a larger ratio (0.15≤UT_ce/Ga_ce<0.30) for heat suppression. This localized quality differentiation ensures each region performs its primary function effectively.
3Temperature
If a uniform thick undertread is used across the entire tread, then heat build-up is suppressed, but the cap tread gauge is insufficient for preventing cracks and fractures in shoulder regions
Solution Approach 1:
The patent resolves this contradiction by implementing non-uniform undertread gauge distribution across the tread. The center land portion features a thicker undertread (larger UT_ce/Ga_ce ratio) for heat build-up suppression, while the shoulder land portion has a thinner undertread (smaller UT_sh/Ga_sh ratio) to preserve cap tread strength for crack and fracture prevention. This spatial variation in material thickness allows simultaneous optimization of thermal and mechanical 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 effectively suppresses heat build-up and cracks, enhancing both tire rolling resistance and durability performance.
Implementation Method 1
the loss tangent tanδ_ut of the undertread at 60°C has a relationship tanδ_ut <0.10
Data Source
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AI summary
This pneumatic tire (1) includes a carcass layer (13), a pair of cross belts (141, 142) disposed on an outer side of the carcass layer (13) in a radial direction, and a tread rubber (15) including a cap tread (151) and an undertread (152) that are layered, the tread rubber (15) being disposed on the outer side of the cross belts (141, 142) in the radial direction. Additionally, the loss tangent tanδ_cap of the cap tread 151 at 60°C has the relationship tanδ_ut < tanδ_cap with respect to the loss tangent tanδ_ut of the undertread 152 at 60°C. In addition, a maximum gauge (UT_ce) of the undertread (152) in center land portions (32, 34) has the relationship 1.20 ≤ UT_ce/UT_sh ≤ 2.50 with respect to a maximum gauge (UT_sh) of the undertread (152) in ground contact regions of shoulder land portions (31, 35).