Pneumatic Tire Dual-Layer Sidewall Rolling Resistance
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Solution Overview
Problem
Heavy-duty pneumatic tires face a challenge in reducing rolling resistance while maintaining durability, as extending low heat generating rubber to bead portions increases strain and potentially reduces durability.
Innovation Solution
A tire design with a dual-layer sidewall structure, where the inner layer has a lower loss tangent and complex elastic modulus than the outer layer, allowing the inner layer to be extended to the bead portion without compromising durability by adjusting the interfacial position between the outer layer and the chafer, and incorporating a turned-up carcass ply and fillers for enhanced durability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the inner layer made of low heat generating rubber is extended to the bead portions, then rolling resistance is reduced, but strain in the bead portions increases and durability is reduced
Solution Approach 1:
The patent applies local quality by creating a dual-layer sidewall structure where the inner layer (made of low heat generating rubber with low loss tangent) is extended to the bead portions, while the outer layer provides protective coverage. This localized application of low heat generating rubber to specific regions (sidewalls and bead portions) reduces rolling resistance without compromising overall durability, as the rubber composition is optimized for each specific location's functional requirements.
2Loss of energy
If the proportion of low heat generating rubber is increased to further reduce rolling resistance, then fuel efficiency improves, but the complex elastic modulus decreases and strain protection capability is reduced
Solution Approach 1:
The patent segments the sidewall into two distinct layers with different rubber compositions and properties. The inner layer uses low heat generating rubber with low loss tangent for energy efficiency, while the outer layer uses rubber with higher complex elastic modulus for strength and protection. This segmentation allows each layer to perform its specialized function optimally without compromising the other, resolving the contradiction between reducing rolling resistance and maintaining strength.
Solution Approach 2:
The patent employs composite materials by combining two different rubber compositions in a layered structure. The inner layer comprises low heat generating rubber (such as natural rubber or polybutadiene rubber) with specific loss tangent characteristics, while the outer layer uses rubber compounds with higher elastic modulus. This composite approach enables the tire to simultaneously achieve low rolling resistance and high durability through the synergistic combination of materials with complementary properties.
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 reduces rolling resistance while maintaining high durability by minimizing strain in the bead portions and improving the tire's overall performance.
Implementation Method 1
a loss tangent LTi of the inner layer is less than a loss tangent LTo of the outer layer
Implementation Method 2
a complex elastic modulus Ei* of the inner layer is less than a complex elastic modulus Ec* of the chafers
Data Source
Figure 1
Figure 2
AI summary
In a tire 2 of the present invention, sidewalls 6 each include an outer layer 6a, and an inner layer 6b disposed inward of the outer layer 6a in the axial direction. A loss tangent of the inner layer 6b is less than a loss tangent of the outer layer 6a. When Hr represents a height, in the radial direction, from a bead base line BBL to an outer side end of a rim R, and Hi represents a height, in the radial direction, from the bead base line BBL to an inner side end 46 of the inner layer 6b, a ratio (Hi/Hr) of the height Hi to the height Hr is greater than or equal to 0.0 and not greater than 3.0.