Pneumatic Tire Bead Structure for Lightweight Cornering Stability
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Solution Overview
Problem
Pneumatic tires face a decrease in cornering power due to reduced lateral spring coefficient when simplifying tire structures and reducing weight, such as thinning rubber in sidewall portions or reducing bead filler height.
Innovation Solution
A pneumatic tire design featuring bead fillers with a storage modulus E1′ and rubber chafers with a storage modulus E2′, where the ratio E2′/E1′ ranges from 0.4 to 1, and the tire includes a carcass with organic fiber cords and a reinforcing member extending at an angle to enhance cornering power while maintaining weight reduction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of moving object
If rubber in sidewall portions is thinned or bead filler height is reduced to simplify tire structure and reduce weight, then fuel efficiency is improved, but cornering power decreases due to decreased lateral spring coefficient
Solution Approach 1:
The patent applies local quality by providing rubber chafers with specific storage modulus properties only in the bead portion area where they are needed for cornering power, while allowing other parts of the tire to be lightweighted. The rubber chafers are positioned to extend in the tire width direction from the inner side, creating a localized reinforcement zone that improves lateral spring coefficient without increasing overall tire weight significantly.
Solution Approach 2:
The patent changes the material parameter (storage modulus) of the rubber chafers to be within a specific range (0.4≤E2′/E1′≤1) relative to the bead fillers. This parameter optimization allows the rubber chafers to provide sufficient stiffness for cornering power while maintaining compatibility with the lightweighting strategy. The specific modulus ratio ensures the rubber chafers are stiff enough to resist lateral deformation but not so stiff as to cause excessive weight or comfort issues.
2Ease of manufacture
If bead filler height is reduced to simplify structure, then manufacturing is easier and weight is reduced, but lateral spring coefficient decreases leading to lower cornering power
Solution Approach 1:
The patent segments the bead portion structure into distinct functional zones: bead fillers for basic structural support and rubber chafers for lateral stiffness enhancement. This segmentation allows each component to be optimized independently - the bead fillers can be kept simple for ease of manufacture, while the rubber chafers provide the necessary lateral spring coefficient for cornering power. The rubber chafers extend from the inner side in the tire width direction, creating a separate functional element that addresses the lateral stiffness issue without complicating the overall manufacturing process.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The design effectively prevents a decrease in cornering power by reducing the rotational component of lateral displacement, thereby maintaining tire stability and performance while minimizing weight increase.
Implementation Method 1
when a storage modulus of the bead fillers is E1′, and a storage modulus of the rubber chafers is E2′, the ratio E2′/E1′ satisfies 0.4≤E2′/E1′≤1
Data Source
AI summary
Provided is a pneumatic tire including: a pair of bead cores embedded in a pair of bead portions; and a carcass including one or more carcass plies extending in a toroidal form between the pair of bead cores, wherein bead fillers are disposed on an outer side in a tire radial direction of the bead cores, rubber chafers are provided on an outer side in a tire width direction of the bead fillers, and when a storage modulus of the bead fillers is E1′, and a storage modulus of the rubber chafers is E2′, the ratio E2′/E1′ satisfies 0.4≤E2′/E1′≤1.