Clinch Apex Rubber Composition for Tire Fuel Efficiency and Crack Resistance
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Solution Overview
Problem
Existing tires face challenges in achieving both improved fuel efficiency and crack resistance, with existing solutions focusing primarily on crack resistance without considering the overall performance enhancement.
Innovation Solution
A tire design incorporating a rubber composition for the clinch apex with a loss tangent of less than 0.25 and a complex elastic modulus of 2.0 MPa or more, along with a specific contact length between the sidewall and clinch apex, and the use of recovered carbon black, combined with minute protrusions on the sidewall to disperse strain and reduce stress concentration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the rubber composition for the clinch apex has high crack resistance, then the tire durability is improved, but the fuel efficiency deteriorates due to increased rigidity
Solution Approach 1:
The patent applies local quality by creating a transition zone between the clinch apex and sidewall where the rubber composition gradually changes in hardness. The clinch apex uses harder rubber (higher modulus) for crack resistance, while the sidewall uses softer rubber for fuel efficiency. The contact portion of 5-30mm length provides a gradient transition that locally adapts the material properties to satisfy both contradictory requirements in different zones.
Solution Approach 2:
The patent changes the physical parameters of the rubber composition, specifically controlling the loss tangent at 70°C to be less than 0.25 and the complex elastic modulus to be 2.0 MPa or more. By precisely adjusting these parameters, the rubber achieves optimal balance between energy dissipation (fuel efficiency) and structural integrity (crack resistance), resolving the contradiction through quantitative parameter optimization.
2Reliability
If the contact length between sidewall and clinch apex is increased, then the strain dispersion is improved and crack resistance is enhanced, but the rigidity difference increases and fuel efficiency deteriorates
Solution Approach 1:
The patent optimizes the contact length parameter to a specific range of 5-30mm. This quantitative parameter control ensures that the transition zone is long enough to disperse strain and prevent crack propagation, yet short enough to minimize rigidity differences that would increase rolling resistance and reduce fuel efficiency.
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 enhances both fuel efficiency and crack resistance by reducing rigidity differences and strain, thereby improving overall tire performance.
Implementation Method 1
a loss tangent at 70°C, 70°C tan δ C , of less than 0.25, wherein a complex elastic modulus at 70°C, in MPa, of a rubber composition constituting the sidewall, 70°CE* S , is 2.0 or more
Data Source
Figure 1
Figure 2~3
Figure 4~5
AI summary
Provided is a tire comprising a pair of sidewalls (2) located in side parts, and a pair of clinch apexes (3) that are located on inner sides of the sidewalls in a radial direction and in contact with a rim, wherein a rubber composition constituting the clinch apex comprises a recovered carbon black, and has a loss tangent at 70°C, 70°C tan δC, of less than 0.25, wherein a length of a contact portion of the clinch apex and the side wall on a tire meridian cross section including a tire rotation axis is 5 mm or more and 30 mm or less, and wherein a complex elastic modulus at 70°C of a rubber composition constituting the sidewall, 70°CE*S, is 2.0 or more.