Tire Casing Shoulder Damage Resistance and Fuel Efficiency
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Solution Overview
Problem
Existing tire manufacturing methods fail to simultaneously enhance low fuel consumption and external damage resistance of the sidewall part, particularly the shoulder portion near the road surface, in a two-stage vulcanization process.
Innovation Solution
A tire casing with a specific rubber composition and structure, including side rubber members (A) and (B), is used, where side rubber member (A) contains natural or synthetic rubber and carbon black with a nitrogen adsorption specific surface area of 70-150 m^2/g, and side rubber member (B) contains natural or synthetic rubber and carbon black with a nitrogen adsorption specific surface area of 25-60 m^2/g, both optimized for vulcanization and adhesion to enhance both low fuel consumption and external damage resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a single-layer sidewall rubber composition is used, then the manufacturing process is simple, but it is difficult to simultaneously achieve low rolling resistance and high external damage resistance
Solution Approach 1:
The sidewall rubber is divided into two distinct layers: an outer layer with high hardness and high loss elastic modulus for external damage resistance, and an inner layer with low hardness and low loss elastic modulus for low rolling resistance. This segmentation allows each layer to independently optimize its function without compromising the other.
Solution Approach 2:
Different regions of the sidewall are assigned different rubber compositions and properties. The outer layer uses a rubber composition optimized for durability and damage resistance, while the inner layer uses a composition optimized for energy efficiency and low rolling resistance, allowing local optimization of each region's function.
2Strength
If the outer layer is made thick to increase external damage resistance, then durability improves, but low fuel consumption deteriorates due to increased rolling resistance
Solution Approach 1:
The outer layer is designed with specific thickness and material properties optimized for damage resistance, while the inner layer compensates for energy efficiency. This allows the outer layer to be sufficiently thick for protection without the entire sidewall having the high rolling resistance characteristics that would worsen fuel consumption.
Solution Approach 2:
The sidewall uses a composite structure with two different rubber compositions. The outer layer uses a composition with higher carbon black content and specific properties for durability, while the inner layer uses a composition with lower hysteresis loss for energy efficiency, creating a composite material system that balances both requirements.
3Use of energy by moving object
If the inner layer is made thick to increase low fuel consumption, then rolling resistance reduces, but external damage resistance deteriorates
Solution Approach 1:
The inner layer is optimized for energy efficiency with appropriate thickness and material composition, while the outer layer provides the necessary external damage resistance. This local optimization ensures that the inner layer's thickness is sufficient for reducing rolling resistance without compromising the outer layer's protective function.
4Strength
If carbon black with high nitrogen adsorption specific surface area is used, then external damage resistance improves, but rolling resistance increases due to higher hysteresis loss
Solution Approach 1:
Carbon black with high nitrogen adsorption specific surface area (70-150 m²/g) is used in the outer layer to maximize external damage resistance, while carbon black with lower nitrogen adsorption specific surface area (25-60 m²/g) is used in the inner layer to minimize hysteresis loss and rolling resistance. This local differentiation of filler properties resolves the contradiction between durability and energy efficiency.
Solution Approach 2:
The patent uses composite rubber compositions in each layer with different carbon black types and concentrations. The outer layer uses carbon black optimized for strength and damage resistance, while the inner layer uses carbon black optimized for low hysteresis, creating a composite structure that balances energy loss and durability.
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 casing achieves improved low fuel consumption and enhanced external damage resistance of the sidewall part, balancing heat generation properties and durability, making it suitable for various pneumatic tires.
Implementation Method 1
carbon black having a nitrogen adsorption specific surface area (N2 SA, as measured according to JIS K 6217-2:2001) of from 70 to 150 m2/g
Data Source
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AI summary
The present invention provides a tire casing including a sidewall part, a bead part, a carcass ply, and a belt part and having been previously vulcanized prior to sticking a tread member, wherein when a distance from an end part of the tread member joint surface to an end part of the bottom surface of the bead part along the surface of the sidewall part is defined to be 1, the tire casing has a side rubber member (A) extending in a proportion of from 0.09 to 0.30 of the distance along the surface of the sidewall part from the end part of the tread joint surface, and the side rubber member (A) contains 100 parts by mass of a rubber component comprising at least one or more selected from the group consisting of a natural rubber, a synthetic isoprene rubber, a polybutadiene rubber, and a styrene-butadiene copolymer rubber, and from 40 to 100 parts by mass of carbon black having a nitrogen adsorption specific surface area (N2SA, as measured according to JIS K6217-2:2001) of from 70 to 150 m2/g. Thus, a tire casing capable of not only enhancing low fuel consumption but also enhancing external damage resistance of a shoulder portion of a sidewall part close to a road surface is provided.