Pneumatic Tire Belt Reinforcement With Tuned Cord Rigidity
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Solution Overview
Problem
Conventional pneumatic tires using steel cords with large filament diameters for increased strength face challenges in achieving both high-speed durability and driving stability due to increased tire weight and bending rigidity, which reduces the ground contact area.
Innovation Solution
A pneumatic tire design with a belt layer having steel cords with a filament diameter of 0.10 mm to 0.25 mm, combined with an organic fiber belt reinforcing layer, adhering to specific relationships represented by Expressions (I) and (II), balances bending rigidity and restraining force to achieve reduced weight and improved stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If steel cords with large filament diameter are used to increase strength, then high-speed durability is improved, but tire weight increases and bending rigidity increases, reducing ground contact area and deteriorating driving stability
Solution Approach 1:
The patent specifies a filament diameter range of 0.10 mm to 0.25 mm for steel cords, optimizing the parameter to achieve the right balance between strength (for high-speed durability) and weight. This parameter optimization allows the tire to maintain sufficient structural strength while avoiding excessive weight gain that would compromise driving stability and ground contact area.
Solution Approach 2:
The patent employs a composite structure combining steel cords (for strength and high-speed durability) with rubber matrix material. This composite approach allows the steel cords to provide the necessary tensile strength for high-speed operation while the rubber matrix distributes loads and maintains flexibility, achieving both durability and stability without excessive weight.
2Reliability
If steel cords with large filament diameter are used to increase strength, then high-speed durability is improved, but bending rigidity of belt ply increases, reducing ground contact area and deteriorating driving stability
Solution Approach 1:
The patent optimizes the filament diameter parameter within the range of 0.10 mm to 0.25 mm to control the bending rigidity of the belt ply. By keeping the diameter within this range, the steel cords provide sufficient strength for high-speed durability while preventing excessive bending rigidity that would reduce ground contact area and compromise driving stability.
Solution Approach 2:
The patent applies steel cords with specific filament diameter characteristics locally in the belt ply structure, where they provide strength enhancement without making the entire tire structure overly rigid. The localized use of optimized steel cord parameters allows high-speed durability in critical areas while maintaining overall tire flexibility and ground contact characteristics for driving stability.
Data Source
AI summary
A pneumatic tire (1) including: a belt layer (20); and a belt reinforcing layer (30), in which: a filament diameter of each of steel cords of belt ply (21) is more than 0.10 mm and less than 0.25 mm; and A, B, and C satisfy relationships represented by the following, Expression (I): B/A<400 and Expression (II): 600<C/A<2000, where: A [N/inch] is a bending load per unit width of a sheet of the belt ply (21); B [N/inch] is a product of a load at 2% elongation of each of organic fiber cords of belt reinforcing ply (31) [N/cord] and the number of the organic fiber cords [cord/inch]; and C [N/inch] is a product of a load at 5% elongation of each of the organic fiber cords [N/cord] and the number of the organic fiber cords [cord/inch].