Pneumatic Tire Bead Insulation Rubber Layer Design
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Solution Overview
Problem
The durability of pneumatic tires is compromised when damage occurs near the radially outer edge of the filler in existing bead reinforcing structures.
Innovation Solution
A pneumatic tire design featuring a carcass ply with a topping rubber, a primary bead apex rubber, an insulation rubber layer, and a subsidiary bead apex rubber layer, where the complex elastic modulus of the insulation rubber layer is greater than or equal to the topping rubber, and the subsidiary bead apex rubber layer's radially outer edge is positioned between 30% to 55% of the tire's cross-sectional height, enhancing rigidity and dispersing strain.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a filler made of high-hardness crosslinked rubber is provided in the bead reinforcing structure, then rigidity is improved, but durability deteriorates when damage occurs near the radially outer edge of the filler
Solution Approach 1:
The patent applies local quality by creating distinct rubber layers with different properties at different locations. The primary bead apex rubber has higher rigidity (complex elastic modulus ≥ 1.5 MPa) to maintain structural strength, while the insulation rubber layer has lower rigidity (complex elastic modulus ≥ 0.8 MPa but less than primary bead apex rubber) to reduce stress concentration and prevent damage propagation at the radially outer edge, thus improving durability without sacrificing overall rigidity
Solution Approach 2:
The patent uses composite materials by combining multiple rubber layers with different elastic moduli. The bead portion comprises a composite structure of primary bead apex rubber and insulation rubber layer, where each layer has specifically controlled complex elastic modulus values. This composite approach allows the structure to simultaneously achieve high rigidity from the primary bead apex rubber and enhanced durability from the more compliant insulation rubber layer
2Stability of the object's composition
If the radially outer edge of the subsidiary bead apex rubber layer is positioned at specific height range, then steering stability is improved, but structural complexity increases
Solution Approach 1:
The patent applies parameter changes by precisely controlling the positional parameter of the subsidiary bead apex rubber layer's radially outer edge within a specific height range (30%-55% of tire cross-sectional height from bead base line). This parameter optimization achieves improved steering stability while the multi-layer rubber structure, though complex in composition, follows systematic design rules that manage the overall structural complexity
3Manufacturing precision
If multiple rubber layers with different elastic moduli are provided, then local deformations are suppressed, but manufacturing complexity increases
Solution Approach 1:
The patent applies segmentation by dividing the bead portion into multiple distinct rubber layers: primary bead apex rubber and insulation rubber layer, each with specifically controlled complex elastic modulus values. This segmentation allows independent optimization of each layer's properties to suppress local deformations, while the systematic layering approach provides a manageable manufacturing process despite the increased structural complexity
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
This design improves durability and steering stability by reducing rigidity changes and suppressing local deformations, while maintaining high rigidity and reducing the risk of defects and increased mass.
Implementation Method 1
a complex elastic modulus E*a of the insulation rubber layer is not smaller than a complex elastic coefficient E*b of the topping rubber of the carcass ply
Data Source
AI summary
A pneumatic tire comprises a carcass which comprises a carcass ply composed of a main portion extending between bead portions and a pair of turned-up portions turned-up around respective bead cores. The bead portion is provided with: a primary bead apex rubber disposed between the carcass-ply main portion and the carcass-ply turned-up portion; an insulation rubber layer extending radially outwardly through between the carcass-ply main portion and the carcass-ply turned-up portion; and a subsidiary bead apex rubber layer disposed on the axially outside of the carcass-ply turned-up portion. The radially outer edge of the insulation rubber layer is located radially outside the radially outer edge of the subsidiary bead apex rubber layer. The complex elastic modulus of the insulation rubber layer is equal to or greater than the complex elastic modulus of the topping rubber of the carcass ply.