Pneumatic Tire Bead Toe Design for Rim Seal Integrity
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Solution Overview
Problem
Pneumatic tires face challenges in suppressing bead toe deformation while maintaining reinflatability after retreading, as rounding the bead toe to prevent deformation reduces the surface area engaging with the rim wheel, leading to air leakage issues during reinflation.
Innovation Solution
A pneumatic tire design featuring bead portions with specific angular configurations and a rubber layer with a complex elastic modulus of 3 MPa to 7 MPa and elongation at break from 200% to 350%, allowing the bead toe to be shaped to minimize deformation while ensuring effective engagement with the rim wheel for reinflation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If the bead toe is rounded to suppress deformation, then the bead toe deformation is reduced, but the surface area of the bead portion that engages with the rim wheel decreases, leading to decreased hermeticity and air leakage
Solution Approach 1:
The bead portion is designed with different geometric characteristics at different locations: the bead toe has a specific angle (105° to 150°) to suppress deformation, while the engaging portion maintains sufficient surface area for hermeticity. This local differentiation allows each region to optimize its function without compromising the other.
Solution Approach 2:
The patent specifies precise parameter ranges for the bead toe angle (105° to 150°) and the angle between the imaginary line and line segment (0° to 25°). By controlling these geometric parameters within specific ranges, the invention achieves both bead toe deformation suppression and adequate engaging surface area for hermeticity.
2Stability of the object's composition
If the bead toe is rounded to suppress deformation, then the bead toe becomes more stable, but the engaging surface area decreases, making reinflation difficult after retreading
Solution Approach 1:
The bead portion design differentiates between the bead toe region (optimized for stability with specific angle) and the engaging portion (optimized for reinflation with sufficient surface area). This local quality differentiation ensures that rounding the bead toe for stability does not compromise the engaging surface needed for easy reinflation after retreading.
Solution Approach 2:
By controlling the bead toe angle within 105° to 150° and the angle between the imaginary line and line segment within 0° to 25°, the invention achieves optimal balance between bead toe stability and engaging surface area, enabling both deformation suppression and easy reinflation after retreading.
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 design effectively suppresses bead toe deformation and maintains reinflatability, preventing air leakage and ensuring the tire remains usable after retreading.
Implementation Method 1
an elongation at break from 200% to 350%
Data Source
AI summary
A pneumatic tire includes a bead portions and a bead core at the bead portions, the tire being mounted to a 15°-tapered specified rim. The bead portions include a portion inward in a radial direction of an extension line of an inner circumferential surface of the bead core, the extension line extending in the lateral direction, that is positioned outward in the tire lateral direction of an imaginary line passing through a first intersection point between the extension line and a tire inner surface and extends inward in the tire radial direction from the extension line at an angle perpendicular to the extension line. An angle α formed by the imaginary line and a line segment passing through a second intersection point between a bead base and the tire inner surface and the first intersection point between the extension line and the tire inner surface is from 0° to 25°.