Tire Tread Modulus Zoning and Belt Extension for Steering Stability
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Solution Overview
Problem
Two-wheeled automotive tires face poor steering stability during cornering due to rapid contact region shifts between straight running and cornering, which applies a great lateral force to the shoulder region with low modulus, leading to inadequate steering stability.
Innovation Solution
A tire design with a high modulus center region for straight running stability and low modulus shoulder regions for cornering grip, combined with a belt extending to the sidewalls and specific tilt angles for enhanced transient characteristics and steering stability, including a belt ply with cords tilted between 70 to 90 degrees and a ratio of belt height to tread height between 0.1 and 0.5.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the modulus of the shoulder region is kept low to improve grip performance in cornering, then steering stability in cornering deteriorates due to poor resistance against lateral force during rapid contact region shifts
Solution Approach 1:
The patent applies local quality by creating distinct modulus zones within the tread: the center region has high modulus for straight running stability, while the shoulder region has low modulus for cornering grip. This spatial differentiation of material properties allows each region to perform its specialized function optimally.
Solution Approach 2:
The patent uses composite materials by combining rubber compositions with different moduli in specific tread regions. The tread is formulated with varying crosslinking densities and compound compositions to achieve the desired modulus distribution, creating a composite structure that balances conflicting performance requirements.
2Stability of the object's composition
If the belt extends to the sidewalls with high tilt angle to improve steering stability and transient characteristic, then the complexity of tire structure increases
Solution Approach 1:
The patent applies dynamics by designing a belt structure that is optimized for transient conditions during cornering. The belt extends to the sidewalls and incorporates cords with tilt angles of 35 degrees or less, creating a dynamic reinforcement system that responds to lateral forces during rapid contact region shifts between straight running and cornering.
Solution Approach 2:
The patent uses another dimension by extending the belt structure in the axial direction to the sidewalls, adding dimensional complexity to the tire structure. This extension creates a three-dimensional reinforcement network that provides enhanced stability during transient cornering conditions.
Data Source
Figure 1
Figure 2~3
AI summary
A tire (2), for use in two-wheeled automotive vehicles, which is excellent in grip performance, steering stability, and transient characteristic, is provided. In the tire (2), a tread (4) includes a center region (20), and a pair of shoulder regions (22) disposed outward of the center region (20) in an axial direction. The center region (20) and the shoulder regions (22) are each formed by a crosslinked rubber composition. A modulus Ms of the rubber composition of each shoulder region (22) is lower than a modulus Mc of the rubber composition of the center region (20). A belt (12) extends inward of the sidewalls (6) in the axial direction. A ratio Hb/H of a height Hb from a bead base line (BL) to an end (Pb) of the belt (12) relative to a height H from the bead base line (BL) to each end (Pe) of the tread (4) is greater than or equal to 0.1, and not greater than 0.5.