Resin-Coated Bead Cores for Run-Flat Tire Rim Separation
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Solution Overview
Problem
Run-flat tires with side reinforcing rubbers face issues with bead portions coming off the rim during abnormal travel conditions, limiting their durability.
Innovation Solution
The tire design features bead cores covered with resin, a carcass anchored on these cores, side reinforcing rubbers, and a belt layer formed by winding a cord in a spiral pattern with resin, enhancing torsional and out-of-plane rigidity to prevent bead separation and buckling, while reducing the thickness of side reinforcing rubbers for improved handling stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If side reinforcing rubbers are provided at the tire side portions, then buckling of the tire side portions is suppressed, but bead portions may come off the rim
Solution Approach 1:
The patent uses a composite structure combining rubber and resin materials. The bead core is formed by covering a wire with resin, creating a composite bead core that provides both flexibility and high rigidity. This composite material approach allows the bead portion to maintain strong attachment to the rim while the side reinforcing rubbers suppress buckling, thus resolving the contradiction between buckling suppression and bead attachment reliability.
Solution Approach 2:
The patent applies different material properties to different parts of the tire. The bead core uses resin-covered wire for high rigidity and strong rim attachment, while the side reinforcing rubbers use rubber material for buckling suppression. This local differentiation of material quality allows each part to perform its specific function optimally without compromising the other, resolving the contradiction between these two requirements.
2Stability of the object's composition
If the belt layer is formed by covering cord with rubber, then flexibility is maintained, but out-of-plane bending rigidity is low causing tread buckling
Solution Approach 1:
The belt layer is formed by covering a cord with resin instead of rubber, creating a composite structure with high out-of-plane bending rigidity. The resin material provides the necessary stiffness to prevent tread buckling during run-flat traveling, while the cord core maintains flexibility. This composite material approach resolves the contradiction between maintaining flexibility and increasing out-of-plane bending rigidity.
3Ease of operation
If intersecting belt layer is used to prevent tread deformation, then handling stability is improved, but tire weight increases
Solution Approach 1:
The patent uses a resin-covered cord in the belt layer that provides high in-plane shearing rigidity. The resin material's inherent high rigidity properties allow a single belt layer to effectively resist tread deformation during turning and handling, eliminating the need for an intersecting belt layer. This resolves the contradiction between handling stability and tire weight by achieving the necessary rigidity with a lighter, single-layer construction.
Data Source
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AI summary
A run-flat tire has: a pair of bead cores, each bead core formed by covering a wire with resin; a carcass that straddles the pair of bead cores, and having end portions that are anchored on the bead cores; side reinforcing rubbers that are provided at tire side portions, and that extend in a tire radial direction along an inner surface of the carcass; and a tread that is provided at an outer side, in a tire radial direction, of the carcass.