Pneumatic Tire Bead Reinforcement for Crack Resistance
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Solution Overview
Problem
Pneumatic tires used in heavy vehicles face durability issues due to protruding deformation of the bead portion, leading to strain on the wound-up end of the chafer, which can result in cracks and gas leakage.
Innovation Solution
Incorporating adhesive rubber with a higher modulus than the inner liner rubber, positioned between the carcass ply and inner liner rubber, to cover and reduce strain on the wound-up ends of the chafer, while maintaining sufficient thickness of the inner liner rubber to prevent gas transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the chafer is arranged along the carcass ply to prevent separation, then the risk of separation is reduced, but the wound-up end of the chafer is subjected to great strain due to bead portion protruding deformation, leading to crack generation
Solution Approach 1:
The patent introduces an adhesive rubber layer as an intermediary component between the inner liner rubber and the chafer. This adhesive rubber has a higher modulus than the inner liner rubber and is positioned to cover the wound-up end of the chafer, thereby mediating the strain distribution and protecting the chafer's wound-up end from direct stress concentration that would otherwise lead to crack generation
Solution Approach 2:
The patent changes the physical parameter (modulus) of the rubber material by introducing adhesive rubber with a higher modulus than the inner liner rubber. This parameter change allows the adhesive rubber to better resist deformation and reduce strain on the chafer's wound-up end while maintaining the overall flexibility needed for tire operation
2Reliability
If the inner liner rubber thickness is increased to prevent gas transmission, then gas leakage is prevented, but the strain on the chafer wound-up end increases due to reduced flexibility
Solution Approach 1:
The patent applies local quality by creating a differentiated rubber structure where adhesive rubber with different properties (higher modulus) is placed specifically at the location of the chafer's wound-up end, while the rest of the inner liner rubber maintains its original properties. This localized modification addresses the strain concentration issue without compromising the overall gas tightness provided by the inner liner rubber
3Strength
If the adhesive rubber thickness is increased to cover the wound-up end, then strain on the chafer is reduced, but the thickness of the inner liner rubber is reduced, potentially compromising gas transmission prevention
Solution Approach 1:
The patent segments the inner liner rubber structure into two distinct functional layers: the inner liner rubber that provides gas tightness and the adhesive rubber that provides strain protection at the chafer's wound-up end. This segmentation allows each layer to be optimized for its specific function without compromising the other, as the adhesive rubber is positioned only where needed to cover the wound-up end
Data Source
AI summary
A pneumatic tire includes a carcass ply wound up from an inner side to an outer side around bead cores, chafers wound up from an outer side to an inner side around the bead cores, and an inner liner rubber which is arranged in an inner side of the carcass ply, wherein a squeegee rubber having a higher modulus than the inner liner rubber is provided closer to the inner liner rubber side than the chafers between the carcass ply and the inner liner rubber, and the squeegee rubber is arranged so as to cover inside wound-up ends of the chafers, and is provided with a thick portion which is thicker than the inner liner rubber, and thin portions which are arranged respectively in an inner side and an outer side in the tire diametrical direction of the thick portion and are thinner than the inner liner rubber.