Pneumatic Tire Bead Area Chipper Structure
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Solution Overview
Problem
The durability of the bead area in pneumatic radial tires is compromised due to high load conditions and frequent starting and stopping, leading to rubber cracking and reduced tire life, especially in urban delivery applications.
Innovation Solution
Incorporating a pair of chippers, one axially inward and one axially outward of the bead apex, to limit deflection forces and reduce stresses along the carcass ply turn up, thereby enhancing the bead area's durability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single carcass reinforcing ply is used with a conventional turn up structure, then the tire structure is simple and easy to manufacture, but the bead area durability is poor due to high shear stresses and rubber cracking under frequent starting and stopping conditions
Solution Approach 1:
The carcass reinforcing ply is divided into multiple segments: a first carcass reinforcing ply and a second carcass reinforcing ply, each with distinct turn up configurations. This segmentation allows each ply to independently manage different stress components, with the first ply handling radial tensions and the second ply managing axial bending stresses, thereby improving bead area durability without requiring a single complex ply structure
Solution Approach 2:
The invention introduces a dual-layer ply structure that adds dimensional complexity to the carcass reinforcement. By stacking two plies with different turn up angles and orientations, the structure creates multiple dimensional layers of stress distribution, enabling better resistance to both radial and axial forces in the bead area
2Reliability
If the carcass ply turn up extends far radially outward, then the bead area coverage is improved, but the shear stresses along the turn up increase leading to rubber cracking
Solution Approach 1:
The carcass reinforcement is segmented into two separate plies, each extending radially outward to different extents. The first ply extends further radially outward to provide broad bead area coverage and protection, while the second ply extends less far but provides additional reinforcement at critical stress points, distributing the shear stress across multiple layers rather than concentrating it in a single extended turn up
Solution Approach 2:
Each carcass reinforcing ply is configured with different local properties: the first ply has a turn up angle optimized for radial coverage, while the second ply has a different turn up angle optimized for stress distribution. This local differentiation allows each ply to address specific stress patterns in different regions of the bead area, improving overall protection while managing shear stresses
3Ease of manufacture
If the tire structure is simplified for easier manufacture, then manufacturing cost is reduced, but the ability to resist deflection forces and prevent rubber cracking under heavy loads is compromised
Solution Approach 1:
The carcass is segmented into two reinforcing plies with distinct functions: the first ply provides foundational radial reinforcement, while the second ply adds targeted reinforcement for deflection resistance. This segmentation allows each ply to be optimized for its specific function, improving overall strength without requiring a single overly complex ply structure that would be difficult to manufacture
Data Source
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AI summary
A pneumatic radial tire is disclosed. The tire (50) comprises a pair of opposing bead areas (52), wherein each bead area (52) includes a bead core (54) and a bead apex (64); at least one carcass reinforcing ply (58), the reinforcing ply (58) including a turn up portion (62) at each bead core (54), each turn up portion (62) including a radially outward end (66); and a pair of chippers (72, 82) disposed axially inwardly of one or each turn up portion outward end (66), the pair of chippers (72, 82) including a first chipper (72) and a second chipper (82). The first chipper (72) is disposed axially inwardly of the respective bead apex (64). The second chipper (82) is disposed axially outwardly of the first chipper (72) and axially inwardly of the respective bead apex (64).