Layered Tire Tread Modulus Tuning for Wet Grip Durability
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Solution Overview
Problem
Tires experience a decline in wet grip performance over time due to thermal deterioration of the cap rubber layer, leading to reduced followability and increased rigidity, which affects fuel efficiency and handling.
Innovation Solution
A tire design with multiple rubber layers in the tread, where the complex elastic modulus and loss tangent of the first and second layers are specifically ratioed to maintain optimal softness and deformation, ensuring consistent wet grip performance throughout the tire's lifespan.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a cap rubber layer with high loss tangent is used in the tread, then wet grip performance when the tire is new is improved, but thermal deterioration occurs during operation causing the rubber to become harder and wet grip performance to deteriorate
Solution Approach 1:
The tread is divided into multiple rubber layers (cap rubber layer and base rubber layer) with different compositions and properties. The cap rubber layer provides high wet grip when new, while the base rubber layer provides stability and resistance to thermal deterioration, thus segmenting the functions to resolve the contradiction between initial performance and long-term stability.
Solution Approach 2:
The tread uses a composite structure of different rubber materials with specific complex elastic modulus ratios. By combining rubber types and adjusting the ratio of complex elastic modulus (E*1/E*2) to 0.85 or more, the composite structure achieves both high initial wet grip and resistance to thermal hardening over time.
2Strength
If the cap rubber layer undergoes thermal deterioration, then the volume of groove becomes smaller and rigidity of tread grounding surface becomes higher, but followability to road surface is lost and wet grip performance deteriorates
Solution Approach 1:
Different regions of the tread are assigned different rubber layer configurations and material properties. The cap rubber layer is designed with specific thickness and composition to maintain local softness and followability, while the base rubber layer provides overall structural support, creating local quality differences that resolve the contradiction between rigidity and followability.
Solution Approach 2:
The invention changes the physical parameters of the rubber layers, specifically controlling the ratio of complex elastic modulus (E*1/E*2 ≥ 0.85) and the thickness ratio of the cap rubber layer (t1/(t1+t2) ≥ 0.40). These parameter adjustments ensure the tread maintains appropriate rigidity while preserving followability to the road surface during operation.
3Productivity
If the complex elastic modulus ratio and loss tangent ratio are optimized, then fuel efficiency is improved and wet grip performance is maintained after abrasion, but the tread structure becomes more complex
Solution Approach 1:
The invention optimizes specific parameters including the ratio of complex elastic modulus (E*1/E*2 ≥ 0.85), loss tangent ratio (tanδ1/tanδ2 ≥ 1.0), and layer thickness ratio (t1/(t1+t2) ≥ 0.40). By precisely controlling these parameters within defined ranges, the multi-layer structure achieves improved fuel efficiency and maintained wet grip performance without excessive complexity.
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 tire maintains improved fuel efficiency and wet grip performance both when new and after abrasion, by maintaining the necessary softness and deformation characteristics of the tread layers, thus addressing the thermal deterioration issue.
Implementation Method 1
a ratio of a complex elastic modulus of the first layer at 30°C to a complex elastic modulus of the second layer at 30°C is 0.85 or more
Implementation Method 2
a ratio of a tan δ of the first layer at 30°C to a tan δ of the second layer at 30°C is 1.0 or more
Data Source
Figure 1~2
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Figure 5~6
AI summary
An object of the present invention is to provide a tire having an improved overall performance of fuel efficiency, wet grip performance at the time of the tire being a new article, and wet grip performance after abrasion. The tire has a tread comprising two or more rubber layers (6, 7) and a complex elastic modulus E* and a loss tangent tan δ of each of the rubber layers have predetermined relationship.