Run-Flat Tire Bead Filler Layout for Durability and Ride Comfort
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Run-flat tires face a trade-off between durability during run-flat travel and ride comfort under normal conditions, as higher radial rigidity improves durability but compromises ride comfort.
Innovation Solution
A run-flat tire design featuring sidewall portions with a side reinforcing rubber layer, a first bead filler, and a second bead filler, where the bead fillers' heights and cross-sectional areas are optimized to balance radial rigidity and comfort, with specific relationships between the reinforcing rubber layer, bead fillers, and carcass overlap to ensure compatible performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a side reinforcing rubber layer is provided on the inner side of the sidewall portions to increase bending rigidity, then run-flat durability is improved, but ride comfort deteriorates due to excessive radial rigidity
Solution Approach 1:
The tire structure is segmented into multiple functional layers: the side reinforcing rubber layer for run-flat durability, the carcass with turned-up portions for structural support, and the bead fillers (first and second) with optimized dimensions for balancing rigidity and comfort. This segmentation allows each layer to contribute differently to overall performance, resolving the contradiction between durability and comfort.
Solution Approach 2:
Different regions of the tire are given different properties: the sidewall portions have high rigidity through the side reinforcing rubber layer for run-flat support, while the bead portions have controlled rigidity through optimized bead filler dimensions. The first bead filler has height ≤30% of tire cross-sectional height and the second has height ≥50%, creating local quality variations that balance durability and comfort.
2Reliability
If higher rigidity in tire radial direction is implemented, then run-flat durability is improved, but ride comfort under normal travel conditions deteriorates
Solution Approach 1:
The patent optimizes specific dimensional parameters of the bead fillers relative to the tire cross-sectional height. The first bead filler height is controlled at ≤30% and the second at ≥50%, creating a specific parameter relationship that provides sufficient radial rigidity for run-flat durability while preventing excessive stiffness that would compromise normal ride comfort.
Solution Approach 2:
The tire employs a composite structure combining the side reinforcing rubber layer, the carcass with turned-up portions, and the bead fillers made of different materials with different rigidity characteristics. This composite approach allows the tire to exhibit appropriate rigidity for run-flat conditions while maintaining comfort for normal travel through the combined properties of different materials.
Data Source
Figure 1
Figure 2
Figure 3A
AI summary
In order to achieve run-flat durability and ride comfort performance in a compatible manner, a run-flat tire (1) includes a side reinforcing rubber layer (10), a first bead filler (51) disposed on an inner side of a turned-up portion (6b) of a carcass (6) in a tire width direction, and a second bead filler (52) disposed on an outer side of the turned-up portion (6b) in the tire width direction. A first bead filler height (HBFL) is 30% or less of a tire cross-sectional height (SH). A second bead filler height (H2FL) is 50% or greater of the tire cross-sectional height (SH). A cross-sectional area (S2FL) of the second bead filler (52) is in a range of from 150% or greater to 400% or less of a cross-sectional area (SBFL) of the first bead filler (51). The side reinforcing rubber layer (10), the first bead filler (51), and the second bead filler (52) satisfy a relationship (0.16 × SH × LI - 1100) ≤ SALL ≤ (0.16 × SH × LI - 800), where SALL represents a sum of cross-sectional areas of the side reinforcing rubber layer (10), the first bead filler (51), and the second bead filler (52), SH represents the tire cross-sectional height, and LI represents a load index.