Tire Stiffness via Carcass Ply Segmentation and Bead Layering
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Solution Overview
Problem
Two-wheeled automotive tires face challenges in achieving optimal stiffness and transient characteristics, as existing methods for adjusting tire stiffness, such as changing the number of carcass plies or extending the outer carcass ply, result in significant changes to transient characteristics and durability issues.
Innovation Solution
A tire design featuring a carcass with a first carcass ply turned up around the beads and a second carcass ply extended between the beads, with a band layered over the turned-up portions, optimizing the ratio of layered width to band width and height ratios to enhance stiffness and transient characteristics without compromising durability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the number of carcass plies is increased to improve tire stiffness, then the stiffness of the tire is improved, but the transient characteristics of the tire are greatly changed
Solution Approach 1:
The carcass is divided into a first carcass ply and a second carcass ply with different configurations. The first carcass ply has turned-up portions at the bead regions while the second carcass ply has ends extending inward near the core. This segmentation allows each ply to contribute differently to tire performance, achieving improved stiffness while maintaining transient characteristics.
2Strength
If the outer carcass ply is extended to a portion near the core to improve stiffness, then the stiffness of the tire is improved, but the end portion is likely to be exposed on the surface and durability is deteriorated
Solution Approach 1:
The second carcass ply is configured to extend inward in the radial direction near the core, but its ends are positioned in the axial direction between the beads and the turned-up portions. This dimensional arrangement allows the ply to contribute to stiffness without exposing its ends on the tire surface, thereby maintaining durability.
3Strength
If the first carcass ply is turned up around the beads to improve stiffness, then the stiffness is improved, but the band and turned-up portions need precise layering which increases manufacturing complexity
Solution Approach 1:
The first carcass ply is turned up only at the bead regions where additional stiffness is needed, while the second carcass ply provides overall structural support. The band is positioned to layer over the turned-up portions at these specific locations. This localized approach improves stiffness where required without unnecessarily complicating the entire tire structure.
Data Source
Figure 1
AI summary
In a tire 2, a band 12 is disposed between a tread 4 and a carcass 10 in a radial direction, and is layered over the carcass 10. A first carcass ply 30 of the carcass 10 has a main portion 30a and turned-up portions 30b. A second carcass ply 32 of the carcass 10 is disposed outward of the main portion 30a of the first carcass ply 30 in the radial direction, and is extended on and between one of the beads 8 and the other of the beads 8. Ends P2 of the second carcass ply 32 are disposed between the beads 8 and the turned-up portions 30b, respectively, on outer side in the axial direction. Ends P1 of the turned-up portions 30b are disposed between the main portion 30a and the band 12. The turned-up portions 30b and the band 12 are layered over each other.