Pneumatic Tire Tread Layer Elastic Modulus Ratio
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Solution Overview
Problem
Existing pneumatic tires face challenges in achieving high speed durability and steering stability while maintaining braking performance, as previous technologies have compromised on one aspect to improve another.
Innovation Solution
A pneumatic tire design with a tread part comprising a cap tread layer and an under tread layer, where the storage elastic moduli of the rubber compositions satisfy specific ratios and cross-sectional area ratios, enhancing durability and steering stability by using high storage elastic modulus rubber compositions and optimizing the carbon black content.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the tan δ of rubber is minimized to increase high speed durability, then heat generation is reduced and durability is improved, but braking performance is decreased
Solution Approach 1:
The patent applies different rubber compositions with different tan δ values to different tread layers: the cap tread layer uses rubber with lower tan δ (0.045-0.085) for heat resistance and durability, while the under tread layer uses rubber with higher tan δ (0.065-0.105) for braking performance. This local differentiation allows each layer to optimize for its specific function without compromising the other.
Solution Approach 2:
The patent uses composite rubber compositions in each tread layer, combining multiple rubber types (natural rubber, polyisoprene, polybutadiene, styrene-butadiene copolymer) with specific proportions to achieve the desired tan δ range. The cap tread layer composite optimizes for low heat generation, while the under tread layer composite optimizes for high friction and braking performance.
2Reliability
If the storage elastic modulus of the under tread layer is increased to improve high speed durability, then heat resistance and durability are enhanced, but steering stability may be affected
Solution Approach 1:
The patent carefully controls the storage elastic modulus parameter of the under tread layer rubber composition to fall within the specific range of 1.5-3.5 MPa at 60°C. This parameter optimization ensures sufficient heat resistance and durability while maintaining appropriate flexibility for steering stability. The cap tread layer's storage elastic modulus is controlled at 0.6-1.2 MPa to maintain comfort and contact with the road surface.
3Reliability
If the rubber composition is optimized for high speed durability with specific storage elastic modulus ratios, then durability and heat resistance are improved, but the complexity of composition design increases
Solution Approach 1:
The patent establishes clear parameter ranges for rubber composition design: tan δ at 60°C and 20 Hz within specific ranges for each layer, storage elastic modulus ratios between layers (EA/EB = 0.45-0.85), and component proportions (natural rubber 20-40 parts, polyisoprene 30-50 parts, etc.). These quantified parameters provide design guidelines that simplify the composition development process while ensuring optimal 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 tire exhibits improved durability and steering stability, with the specific rubber composition and layer ratios ensuring high speed performance without compromising braking, and maintaining physical properties across temperature changes.
Implementation Method 1
when storage elastic moduli of the compounds (i.e., rubber compositions) are designated as EA and EB, the storage elastic moduli EA (60° C.) and EB (60° C.) determined at a temperature of 60° C. satisfy the following formulae (1) and (2)
Implementation Method 2
controlling the heat generation of compounds, that is, minimizing the tan δ of rubber
Data Source
AI summary
A pneumatic tire with superior durability having a tread part comprising a cap tread layer (layer A) and an under tread layer (layer B), wherein, in the pneumatic tire, when storage elastic moduli of the rubber compositions constituting the layer A and the layer B are designated as EA and EB, the storage elastic moduli EA (60° C.) and EB (60° C.) determined at a temperature of 60° C. satisfy the following formulae (1) and (2):EA(60° C.)/EB(60° C.)≦0.66 (1)10(MPa)≦EB(60° C.) (2)