Pneumatic Tire Bead Core Wedge Shape Rim Disengagement
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Solution Overview
Problem
Pneumatic tires with side reinforcing layers in the sidewall portion face challenges in achieving reduced weight while maintaining sufficient rim disengagement resistance, as existing designs either increase tire weight or compromise on rim disengagement prevention.
Innovation Solution
A pneumatic tire design featuring a bead core with a radially outward wedge shape, where the bead wire is wound in a specific pattern to reduce the number of turns near the vertex and maintain durability, combined with a carcass layer folded back along the bead core, creating a recessed shape that enhances rim disengagement resistance without the need for a bead filler.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the radially inner end portions of the side reinforcing layer extend to the bead portion region, then the wall thickness of the bead portion region increases and tire weight increases, but rim disengagement resistance improves
Solution Approach 1:
The invention extracts the bead filler from the bead portion structure, eliminating the need for additional filler material. The bead core itself is designed with an optimized shape that provides sufficient structural support without requiring extra filler, thereby reducing tire weight while maintaining rim disengagement resistance
Solution Approach 2:
The bead core is designed with non-uniform thickness distribution, having greater thickness at critical locations (bead root and crown regions) and reduced thickness in less critical areas. This localized quality optimization provides sufficient strength where needed while minimizing overall material usage and tire weight
2Reliability
If the side reinforcing layer increases the rigidity of the region where the rim flange abuts the tire, then rim disengagement resistance improves, but tire weight increases
Solution Approach 1:
The invention changes the geometric parameters of the bead core, specifically optimizing its thickness distribution and overall shape. The bead core thickness is designed to be 1.2-1.8 times the wire diameter at critical regions, providing sufficient rigidity for rim disengagement resistance while minimizing weight
3Weight of moving object
If the bead wire is wound with fewer turns near the vertex to reduce weight, then tire weight decreases, but durability may be compromised
Solution Approach 1:
The bead wire winding density is optimized locally, with fewer turns at the vertex region (reducing weight) and sufficient turns at critical stress regions (maintaining durability). The winding pattern is specifically designed to concentrate wire coverage where mechanical stresses are highest
4Reliability
If a bead filler is used to maintain structural support, then rim disengagement resistance improves, but tire weight increases
Solution Approach 1:
The invention completely eliminates the bead filler component from the tire structure. The bead core is designed with optimized geometry and material properties that provide all necessary structural support functions previously requiring filler, thereby removing unnecessary weight
Solution Approach 2:
The bead core is designed to perform multiple functions simultaneously: providing structural support, maintaining rim disengagement resistance, and supporting the tire's mechanical loads. This multi-functionality eliminates the need for separate filler components
Data Source
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AI summary
A pneumatic tire including a side reinforcing layer in a sidewall portion, the pneumatic tire having an enhanced bead portion structure, reduced tire weight, and good rim disengagement resistance. In a meridian cross-section, an external contour shape of the bead core (5) is a polygon formed by common tangent lines of a plurality of circumferential portions of a bead wire (5A), the external contour shape includes a single vertex (Q) with an acute angle located toward the outside in a tire radial direction and a bottom side opposite the vertex (Q), the carcass layer (4) is bent and folded back along a circumference of the bead core (5) in a bead portion (3), a folded back portion (4B) of the carcass layer (4) from a position of an outer end of the bead core (5) in the tire radial direction extends toward a sidewall portion (2) in contact with a body portion (4A), and a distance in the tire radial direction between a center (O) of an arc (R) constituting a profile of a tire outer surface and a straight line (L1) extending in the tire lateral direction through the vertex (Q) is within 20% of a radius r of the arc (R), and a distance in the tire lateral direction between the center (O) of the arc (R) and a straight line (L2) extending in the tire radial direction through the vertex (Q) with respect to the radius r of the arc (R) is within a range of 2r±0.4r.