Pneumatic Tire Bead Core Segmentation for Weight Reduction
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Solution Overview
Problem
Pneumatic tires face a challenge in reducing weight while maintaining durability, particularly in the bead portion where the side reinforcing layer increases thickness and weight, and existing weight reduction methods compromise rigidity and durability.
Innovation Solution
The tire design includes a bead core with a trefoil-shaped multilayer structure, a carcass layer folded back along the bead core, and a filler layer with specific cross-sectional areas and hardness ratios, eliminating the need for a conventional bead filler to enhance rigidity and reduce weight.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a side reinforcing layer is provided on the sidewall portion to support load during puncture, then run-flat performance is improved, but the thickness and weight of the bead portion increase
Solution Approach 1:
The bead core is divided into multiple layers with different numbers of circumferential portions, creating a segmented structure where the innermost layer has fewer portions than outer layers. This segmentation allows weight reduction in the bead portion while maintaining the overall structural integrity needed for run-flat performance.
Solution Approach 2:
The invention applies local quality by providing different structural characteristics at different locations: the bead core has a specific multilayer structure with varying circumferential portions, the folded back portion of the carcass layer is positioned at specific locations, and the filler layer is provided only in the sidewall portion rather than uniformly throughout. This localized approach reduces overall weight while maintaining run-flat performance where needed.
2Weight of moving object
If the bead core structure is modified to eliminate bead filler for weight reduction, then tire weight decreases, but rigidity in the bead portion becomes insufficient
Solution Approach 1:
The invention uses composite materials by combining the multilayer bead core structure (with different numbers of circumferential portions in different layers) with the folded back portion of the carcass layer and the filler layer in the sidewall. This composite approach provides the necessary rigidity without requiring conventional bead filler, achieving weight reduction while maintaining strength.
Solution Approach 2:
The invention addresses rigidity requirements by extending the solution into another dimension: the folded back portion of the carcass layer is positioned to extend from the outer end of the bead core toward the sidewall, creating a three-dimensional structural support system that compensates for the reduced bead filler, while the filler layer is specifically placed in the sidewall dimension to provide additional rigidity where needed.
3Reliability
If the folded back portion of the carcass layer is positioned to contact the body portion from the outer end of the bead core, then structural integrity is improved, but manufacturing complexity increases
Solution Approach 1:
The invention applies preliminary action by pre-positioning the folded back portion of the carcass layer to contact the body portion at the outer end of the bead core during the tire construction process. This pre-positioning ensures proper structural integrity is achieved while simplifying manufacturing, as the components are arranged in their final positions during assembly rather than requiring post-assembly adjustments.
Data Source
AI summary
Of layers configuring a bead core of a pneumatic tire, the width W0 of one of the layers including the greatest number of rows, the width W1, W2 of other of the layers located respectively innermost and outermost in the radial direction satisfy W1>W2 and W2≤0.5×W0. The position of width W0 is inward in the radial direction of the center of the bead core. A carcass is folded and curved along the bead core and extends toward sidewalls where a folded back portion of the carcass contacts a body of the carcass. A rubber occupancy ratio in a closed region formed by the body and the folded back portion is 0.1% to 15%. The cross-sectional area S2 and hardness H2 of a filler outward of the carcass in the lateral direction, and the cross-sectional area S1 and the hardness H1 of the side reinforcing layer satisfy 0.12≤(S2×H2)/(S1×H1)≤0.50.