Dual Layer Pneumatic Tire Tread Design
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Solution Overview
Problem
Pneumatic tire treads experience deformation, leading to increased rolling resistance and unsatisfactory stiffness, which affects tire performance and road contact.
Innovation Solution
A pneumatic tire design featuring a tread with two distinct rubber compounds: a softer outer cap layer for rolling resistance and wet grip, and a stiffer inner cap layer with reinforcement zones extending to the tread surface, using a diene-based elastomer with high surface area carbon black and specific additives for improved stiffness and durability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a single tread compound is used, then manufacturing is simple, but tread deformation occurs leading to increased rolling resistance and reduced stiffness
Solution Approach 1:
The tread is divided into two distinct layers: a first tread layer with a first rubber compound and a second tread layer with a second rubber compound. This segmentation allows each layer to have optimized properties - the first layer provides flexibility and comfort while the second layer provides stiffness and structural support, thereby reducing tread deformation without requiring complete redesign of the entire tread structure.
Solution Approach 2:
Different regions of the tread are assigned different rubber compounds with specific properties. The first rubber compound is formulated with certain filler content and composition for flexibility, while the second rubber compound has different filler content and composition for enhanced stiffness. This local differentiation of material properties allows the tread to exhibit both flexibility where needed and stiffness where required, resolving the contradiction between manufacturing simplicity and structural performance.
2Strength
If tread reinforcement is added to reduce deformation, then stiffness improves, but rolling resistance increases due to heat buildup
Solution Approach 1:
The reinforcement function is segmented from the wear-resistant function by placing the stiffer second rubber compound in the second tread layer specifically positioned to provide structural support and reduce deformation, while the first tread layer maintains optimized composition for lower hysteresis and reduced heat generation. This functional segmentation allows stiffness enhancement without proportionally increasing rolling resistance.
Solution Approach 2:
The rubber compounds in the two layers have different compositional parameters, particularly in filler content and type. The second rubber compound has higher filler content for stiffness, while the first rubber compound has optimized parameters for reduced energy loss. By carefully controlling these compositional parameters in each layer, the patent achieves improved stiffness while minimizing the increase in rolling resistance that would occur with uniform reinforcement throughout the tread.
3Strength
If groove reinforcement is applied, then tire stiffness improves, but manufacturing complexity increases
Solution Approach 1:
The reinforcement function is merged into the second tread layer itself, which is formulated with a stiffer rubber compound. Rather than adding separate reinforcement elements or structures, the patent combines the reinforcement function with the tread layer structure, using the second rubber compound's inherent stiffness properties to provide both structural support and deformation resistance. This merging approach improves stiffness while avoiding the manufacturing complexity of multi-component reinforcement systems.
Data Source
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AI summary
A pneumatic tire is disclosed comprising a carcass and a tread (10) located radially outward of the carcass and extending between the tire sidewalls. The tread (10) provides a radially outermost tread running surface (12) and comprises a first tread layer (14) comprising a first rubber compound and a second tread layer (16) comprising a second rubber compound. The second tread layer (16) is located radially adjacent to the first tread layer (14). The first rubber compound is compositionally distinct from the second rubber compound. The second tread layer (16) comprises one or more integrally formed extensions of the second tread layer (16) extending radially outwardly toward the tread running surface (12). Each of the integrally formed extensions of the second tread layer (16) comprises or forms or encloses a circumferentially continuous groove (20) and at least one reinforcement zone (24, 26) disposed on only one or on both lateral sides of the groove (20). The first rubber compound comprises 100 parts by weight of at least one diene based elastomer, and from 1 to 150 phr of silica. The second rubber compound comprises a diene base elastomer, from 50 to 120 phr of a filler, wherein at least 20 phr of the filler is a carbon black having an iodine adsorption number of at least 100 g/kg, from 1 to 45 phr of a methylene acceptor, from 1 to 25 phr of a methylene donor, and from 1 to 30 phr of at least one additive selected from the group consisting of carbamic resins, liquid diene based polymers having a number average molecular weight in a range of from 1000 to 25000, and aromatic hydrocarbon resins.