Pneumatic Tire Carcass Structure for Sidewall Heat and Separation Control
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Solution Overview
Problem
Pneumatic tires with carcass layers made of organic fiber cords face challenges in achieving both steering stability and high-speed durability due to increased fineness and rigidity leading to heat generation and potential separation at high speeds.
Innovation Solution
A pneumatic tire design with a carcass layer formed from organic fiber cords with specific fineness (4000 dtex to 8000 dtex), intermediate elongation (3.3% to 4.2%), and a twist coefficient (2000 or more), along with an optimized interlayer rubber gauge ratio (0.50 to 0.60) between the body and folded back portions, to enhance rigidity and reduce temperature increase and shear strain.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the fineness of the carcass cord is increased to improve steering stability, then the rigidity in the sidewall portion is improved, but heat generation increases and high-speed durability deteriorates
Solution Approach 1:
The patent applies parameter changes by precisely controlling the fineness of the carcass cord within 4000-8000 dtex and the intermediate elongation within 3.3-4.2%, optimizing the balance between rigidity and heat generation. Additionally, the interlayer rubber gauge ratio G/R is controlled within 0.50-0.60 to manage temperature distribution in the contact region, resolving the contradiction between steering stability and high-speed durability
Solution Approach 2:
The patent uses composite materials by combining organic fiber cords (such as polyester or nylon) with rubber layers to form a carcass layer structure. This composite structure allows the cord to provide rigidity for steering stability while the rubber matrix dissipates heat, preventing excessive temperature rise during high-speed operation
2Strength
If the fineness of the carcass cord is increased to improve steering stability, then the rigidity in the sidewall portion is improved, but the adhesiveness between body portion and folded back portion decreases and separation may occur
Solution Approach 1:
The patent controls the interlayer rubber gauge ratio G/R within 0.50-0.60 in the contact region where the body portion and folded back portion meet. This parameter optimization ensures adequate adhesiveness and prevents separation during high-speed operation while maintaining the rigidity provided by the controlled cord fineness
Solution Approach 2:
The patent applies local quality by differentiating the rubber layer characteristics in the contact region compared to other areas. The interlayer rubber gauge is specifically controlled in the contact region to enhance adhesiveness locally, while the overall carcass cord fineness is optimized for steering stability, creating region-specific properties to resolve the contradiction
Data Source
AI summary
In a pneumatic tire, at least one carcass layer mounted between a pair of bead portions is formed from a carcass cord formed of an organic fiber cord having filament bundles of organic fibers intertwined together, a fineness based on corrected mass of the carcass cord is from 4000 dtex to 8000 dtex, an intermediate elongation of the carcass cord at a sidewall portion under 1.0 cN/dtex load is from 3.3% to 4.2%, and a ratio G/R of an interlayer rubber gauge G between a body portion and a folded back portion to a cord diameter R of the carcass cord, at a contact region where the body portion and the folded back portion are in contact in the carcass layer, is from 0.50 to 0.60.