Tire Sidewall Rubber Layout for Lower Mass and Strain Control
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Solution Overview
Problem
Existing tires face challenges in achieving both durability and mass reduction due to the concentration of strain at specific portions caused by the inclusion of reinforcing rubber layers, which are harder than the protective rubber layers, leading to increased stiffness and potential durability issues.
Innovation Solution
The tire design incorporates a pair of reinforcing rubber layers located between turned-up portions and protective rubber layers, with a varying thickness distribution that includes a smaller thickness at the center portion and larger thickness at other portions, dispersing strain effectively and reducing the overall mass.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the thickness of the protective rubber layer is set based on conventional art concepts, then the tire mass increases, but the durability and strain distribution improve
Solution Approach 1:
The protective rubber layer is designed with non-uniform thickness, being thinner at the center portion (where reinforcing rubber layer is present) and thicker at other portions. This local variation in thickness allows the tire to reduce overall mass while maintaining adequate protection in areas where it is most needed, resolving the contradiction between mass reduction and durability
Solution Approach 2:
The patent changes the thickness parameter of the protective rubber layer from a uniform conventional design to a variable thickness design. By adjusting the thickness parameter locally (thinner at center, thicker at other areas), the patent achieves both mass reduction and maintained durability, directly addressing the technical contradiction
2Strength
If a reinforcing rubber layer is added to improve durability, then the stiffness of the rubber layer increases, but strain concentration occurs leading to reduced durability
Solution Approach 1:
The reinforcing rubber layer is positioned specifically at the center portion of the sidewall, creating a local stiffness enhancement exactly where needed for structural support. This localized reinforcement prevents excessive overall stiffening while maintaining durability in critical areas
Solution Approach 2:
The patent creates a composite structure by combining the protective rubber layer and reinforcing rubber layer. The protective layer provides flexibility and strain distribution, while the reinforcing layer provides localized stiffness. This composite approach resolves the contradiction between stiffness and durability
3Weight of moving object
If the protective rubber layer is made thinner to reduce mass, then the tire mass decreases, but the stiffness of the rubber layer decreases
Solution Approach 1:
The protective rubber layer thickness is optimized locally - thinner at the center portion where the reinforcing layer compensates for stiffness, and thicker at other portions where additional protection is needed. This local quality variation allows mass reduction while maintaining overall stiffness through the reinforcing layer's compensation
Data Source
AI summary
A tire can include a pair of beads, a carcass, a pair of protective rubber layers, and a pair of reinforcing rubber layers. A carcass ply of the carcass can include a ply body and a pair of turned-up portions. Each reinforcing rubber layer can be between the turned-up portion and the protective rubber layer. An outer end of an apex of each bead can be between an outer end and an inner end of the reinforcing rubber layer in a radial direction. A thickness of the protective rubber layer in a zone from a rim contact end to the outer end of the reinforcing rubber layer can be small at a center portion in the radial direction of the reinforcing rubber layer and can be large at another portion.