Pneumatic Tire Bead Recess Design for Steering Stability
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Solution Overview
Problem
Pneumatic tires with recesses in the bead portion area suffer from reduced lateral spring constant, leading to deformation and compromised cornering force and steering stability when a side force is applied during vehicle cornering.
Innovation Solution
A pneumatic tire design with a carcass that includes bead cores and a toroidal carcass ply, featuring a recess on the inner side of the tire radial direction and a specific radius of curvature to maintain tension and prevent deformation, while ensuring a reduced tire widthwise maximum width and gauge reduction to minimize weight and rolling resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of moving object
If a recess is provided in the bead portion area to reduce tire weight, then rolling resistance is reduced and fuel consumption decreases, but the lateral spring constant is reduced causing tire deformation and compromised steering stability
Solution Approach 1:
The patent applies local quality by providing a recess only in the bead portion area while maintaining the original structure in other critical areas. The recess is positioned at specific locations (front and rear bead portions) with controlled dimensions, allowing weight reduction locally without compromising the overall structural integrity and steering stability of the tire.
Solution Approach 2:
The patent utilizes parameter changes by precisely controlling the recess dimensions (depth not exceeding 1/4 of tread section height, width not exceeding 1/3 of tire section width) and positioning (at front and rear bead portions). These parameter optimizations allow the recess to reduce weight while maintaining sufficient lateral spring constant and steering stability.
2Loss of energy
If a recess is provided in the bead portion area to reduce tire weight, then rolling resistance is reduced, but the tire deforms greatly under side force during cornering
Solution Approach 1:
The recess is localized to specific bead portion areas rather than the entire tire structure. This localized modification reduces weight and rolling resistance while preserving the structural integrity of the tread and other load-bearing areas, preventing excessive deformation under side forces during cornering.
Solution Approach 2:
The patent applies partial action by providing recesses at only the front and rear bead portions rather than uniformly across the entire tire. The recess depth and width are controlled to be partial (not exceeding certain proportions), which is sufficient for weight reduction while maintaining adequate structural stability during cornering maneuvers.
Data Source
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AI summary
This disclosure aims to achieve reduction in rolling resistance and ensure excellent steering stability. In this disclosure, a tire widthwise maximum width of a carcass is 1.35W or less; a tire outer surface has a recess; within a second height range h2 and on the outer side in a tire radial direction with respect to bead cores, a radius of curvature of the carcass is 0.46h or more; within a third height range h3, the radius of curvature of the carcass is 0.62h or more; during movement of a virtual point from a bead core height position Hbc toward a third height position H3, a tire gauge at the virtual point is reduced by a reduction amount of 0.025×G0/mm or less; and the tire gauge at the virtual point at the third height position H3 is 10% or more of the tire widthwise maximum width of the bead core.