Asymmetric Bead Core for Tire High-Speed Stability
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Solution Overview
Problem
Pneumatic tires face challenges in maintaining high-speed stability during cornering, as existing designs do not adequately address lateral force distribution and carcass ply inclination.
Innovation Solution
The tire design features a bead core with a tapered shape and an inclined center line, allowing the carcass ply to tilt closer to the tire axial direction, enhancing lateral spring and stability. This is achieved through a specific configuration of bead wire stacking, core dimensions, and rubber distribution, including a core-below region with high elastic modulus rubber and turned-up portions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the bead core is designed with a conventional symmetric shape, then the manufacturing is simple, but the high-speed stability during cornering is insufficient
Solution Approach 1:
The bead core is designed with an asymmetric shape where the outer side (away from tire center) has a larger radius of curvature than the inner side. This asymmetric configuration allows the carcass ply to tilt closer to the tire axial direction, improving lateral spring and high-speed stability during cornering while maintaining manufacturing feasibility
Solution Approach 2:
Different regions of the bead core are given different radii of curvature to optimize local performance. The outer side has a larger radius to promote carcass ply inclination for better cornering stability, while the inner side has a smaller radius to maintain structural integrity and manufacturing simplicity
2Reliability
If the carcass ply is made stiffer to improve stability, then the high-speed stability improves, but the ride comfort deteriorates
Solution Approach 1:
The bead core design enables the carcass ply to dynamically adjust its inclination angle in response to lateral forces during cornering. The asymmetric shape allows optimal ply orientation under load, providing enhanced lateral spring when needed while maintaining flexibility for ride comfort during normal conditions
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 significantly improves high-speed stability by allowing the carcass ply to sufficiently bend under lateral forces, enhancing lateral spring and maintaining rim detachment resistance while ensuring ride comfort and fittability.
Implementation Method 1
the bead wire is stacked so as to form a tapered shape toward an outer side in a tire radial direction
Implementation Method 2
a rubber having a complex elastic modulus not less than 3.0 MPa is preferably disposed in a core-below region
Data Source
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AI summary
A pneumatic tire having excellent high-speed stability is provided. The pneumatic tire is a pneumatic tire 1 including a carcass 6 including a carcass ply 6A extending on and between bead cores 5. Each bead core 5 includes a bead wire 10 extending in a tire circumferential direction. In a tire meridian cross-section, each bead core 5 includes a core outer portion 12 in which the bead wire 10 is stacked so as to form a tapered shape toward an outer side in a tire radial direction. A center line 14 that bisects a taper angle of the core outer portion 12 is inclined toward an outer side in a tire axial direction while extending toward the outer side in the tire radial direction.