Pneumatic Tire Sidewall Reinforcement Geometry
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Solution Overview
Problem
Conventional run-flat tires face a trade-off between run-flat durability and steering stability, as increasing the thickness of the reinforcing rubber layer enhances vertical stiffness but increases rolling resistance, while reducing it compromises durability.
Innovation Solution
A pneumatic tire design with a crescent-like meridian cross-section reinforcing rubber layer, where the radius of curvature of the carcass layer is greater than the tire external contour, optimizing the relationship between these radii to balance vertical stiffness and rolling resistance, and using rayon for carcass cords to enhance tensile strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the thickness of the reinforcing rubber layer is increased to enhance vertical stiffness and run-flat durability, then run-flat durability performance is improved, but rolling resistance increases
Solution Approach 1:
The reinforcing rubber layer is positioned specifically in the shoulder portions of the tire sidewalls, concentrating reinforcement where it is most needed for run-flat durability while minimizing the overall volume of reinforcing material. This localized placement reduces rolling resistance compared to a uniform thick reinforcement across the entire tire cross-section.
Solution Approach 2:
The reinforcing rubber layer is designed with a curved cross-sectional shape that follows the natural curvature of the tire sidewall. This curved geometry optimizes the distribution of reinforcement material, providing maximum structural support in the critical shoulder regions while minimizing material volume and rolling resistance.
2Stability of the object's composition
If the thickness of the reinforcing rubber layer is increased to improve steering stability through enhanced vertical stiffness, then steering stability performance is improved, but rolling resistance increases
Solution Approach 1:
The reinforcing rubber layer is concentrated in the shoulder portions where vertical stiffness is most critical for steering stability. This localized reinforcement provides the necessary structural support for stable steering while minimizing the overall material volume that would otherwise increase rolling resistance.
Solution Approach 2:
The curved cross-sectional shape of the reinforcing rubber layer optimizes its structural efficiency, providing maximum vertical stiffness in the shoulder regions with minimum material. This curved geometry ensures proper load distribution during steering maneuvers while reducing rolling resistance.
3Loss of energy
If the volume of the reinforcing rubber layer is reduced to decrease rolling resistance, then rolling resistance is reduced, but run-flat durability performance decreases
Solution Approach 1:
Instead of uniformly reducing reinforcement throughout the tire, the design concentrates the reinforcing rubber layer specifically in the shoulder portions. This localized placement ensures that run-flat durability is maintained in the critical areas that bear the most stress during deflated operation, while minimizing overall material volume to reduce rolling resistance.
4Loss of energy
If the volume of the reinforcing rubber layer is reduced to reduce rolling resistance, then rolling resistance is reduced, but vertical stiffness and steering stability decrease
Solution Approach 1:
The reinforcing rubber layer is strategically placed in the shoulder portions where vertical stiffness is most critical for steering stability. This localized concentration of reinforcement maintains the necessary structural rigidity for stable steering performance while minimizing the overall volume of reinforcing material to reduce rolling resistance.
Data Source
AI summary
A pneumatic tire includes a reinforcing rubber layer disposed in the sidewall portions and having a crescent-like meridian cross-section; wherein when the tire is assembled on a regular rim and in an unloaded state with an internal pressure of 0 kPa, a radius of curvature (RP) is larger than a radius of curvature (RO), an arc of the radius of curvature (RP) joining an intersection (Pa) of a carcass layer and a straight line (La), an intersection (Pb) of the carcass layer and a straight line (Lb), and an intersection (Pc) of the carcass layer and a straight line (Lc), and an arc of the radius of curvature (RO) joining an intersection (Oa) of the straight line (La) and a tire external contour, an intersection (Ob) of the straight line (Lb) and the tire external contour, and an intersection (Oc) of the straight line (Lc) and the tire external contour.