Multilayer Tire Tread Composition for Low Rolling Resistance
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Solution Overview
Problem
Existing pneumatic tires for trucks and buses face challenges in achieving improved fuel efficiency (low rolling resistance) without compromising durability and steering stability, particularly due to the use of low heat build-up rubber in the undertread layer which affects these performance metrics.
Innovation Solution
A pneumatic tire design with a multilayer tread structure comprising a cap tread layer and an undertread layer, where the undertread layer is composed of a rubber composition blended with specific amounts of carbon black, silica, and a silane coupling agent, and a ratio of hardness and elastic modulus is set to enhance durability and steering stability while reducing heat build-up.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If low heat build-up rubber is used in the undertread layer to improve fuel efficiency, then rolling resistance is reduced, but durability and steering stability deteriorate due to low hardness and elastic modulus
Solution Approach 1:
The patent changes the physical and chemical parameters of the rubber composition by precisely controlling the blended amounts of carbon black (15-45 parts per 100 parts diene rubber), silica (3-30 parts), and silane coupling agent (5-15 mass% of silica). This optimization adjusts the hardness and elastic modulus to achieve the target ratio α (110-140) while maintaining low rolling resistance through reduced heat build-up
Solution Approach 2:
The patent creates a composite rubber composition by blending diene rubber with carbon black, silica, and silane coupling agent. This composite structure combines the low heat build-up properties of the rubber base with the reinforcing effects of carbon black and silica, achieving both fuel efficiency and durability simultaneously
2Duration of action of stationary object
If the undertread layer thickness is increased to improve durability, then durability is enhanced, but heat build-up increases and rolling resistance worsens
Solution Approach 1:
The patent optimizes the thickness proportion G2/G1 (undertread layer thickness to total tread thickness under groove) to be 0.55 or more and 0.80 or less. This parameter control ensures sufficient undertread layer thickness for durability while limiting excessive thickness that would increase heat build-up and rolling resistance
Solution Approach 2:
The patent applies different rubber compositions to different layers: the cap tread layer uses conventional rubber for road contact and durability, while the undertread layer uses the optimized low heat build-up rubber composition. This local differentiation allows each layer to perform its specific function optimally without compromising overall 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 design effectively improves low rolling resistance, durability, and steering stability in a balanced manner by optimizing the rubber composition and layer thickness ratios, ensuring compatibility of these performance attributes.
Implementation Method 1
a silane coupling agent in an amount of 5 mass % to 15 mass % of the silica
Implementation Method 2
15 parts by mass to 45 parts by mass of carbon black having a nitrogen adsorption specific surface area N2SA of 20 m2/g to 85 m2/g and a DBP absorption of 90 mL/100 g to 200 mL/100 g
Data Source
AI summary
A pneumatic tire includes undertread layer made of a rubber composition obtained by blending, per 100 parts by mass of diene rubber, 15 parts by mass to 45 parts by mass of carbon black having a nitrogen adsorption specific surface area N2SA of 20 m2/g to 85 m2/g and a DBP absorption of 90 mL/100 g to 200 mL/100 g, 3 parts by mass to 30 parts by mass of silica, and a silane coupling agent in an amount of 5 mass % to 15 mass % of the silica. A ratio is calculated based on a hardness Hu of an undertread rubber and an elastic modulus Ec and a hardness Hc of a cap tread rubber, is set to 110 to 140. A proportion iof a thickness G2 of the undertread layer to an under-groove rubber gauge G1, is set to 0.55 or more and 0.80 or less.