Radial Tire Bead Structure for Lightweight Stiffness Retention
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Solution Overview
Problem
There is a need for a lightweight pneumatic radial tire that maintains tire performance characteristics and service life while reducing weight, particularly in passenger vehicles, without compromising stiffness and durability.
Innovation Solution
A pneumatic radial tire design featuring a carcass ply with a specific arrangement of ply endings forming a sealed enclosure around the bead core, where apex elements are positioned axially outward from the ply-to-ply contact section, and are in direct contact with its outward surface, eliminating the need for additional reinforcing members in the bead portions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of moving object
If rubber thickness is reduced in sidewall and bead portions, then tire weight is reduced, but tire strength and durability are compromised
Solution Approach 1:
The patent employs composite material structures in the bead portion, combining apex elements (rigid components) with rubber material to create a hybrid construction. This composite approach allows weight reduction in traditional rubber portions while the apex elements provide the necessary structural strength and stiffness, resolving the contradiction between lightweight design and strength maintenance.
Solution Approach 2:
The bead portion is segmented into distinct functional zones: the apex element region providing structural support, the sealed enclosure formed by ply endings, and the rubber portions. This segmentation allows each zone to be optimized independently - the apex elements concentrate reinforcement where needed while reducing overall rubber usage, thereby reducing weight without sacrificing strength.
2Weight of moving object
If weight of internal structure is reduced, then tire weight is reduced, but tire stiffness and performance are compromised
Solution Approach 1:
The apex elements serve as internal structural components made from rigid materials that provide high stiffness-to-weight ratio. These composite structural elements maintain tire stiffness and structural integrity while being lighter than traditional solid rubber constructions, directly addressing the contradiction between weight reduction and stiffness maintenance.
Solution Approach 2:
The apex elements are strategically positioned in the bead portion where structural support is most critical for maintaining tire stiffness during cornering and loading. This localized reinforcement approach provides maximum stiffness benefit with minimum weight, as the rigid apex elements are placed only where needed rather than throughout the entire tire structure.
3Strength
If additional reinforcing members are added in bead portions, then tire strength is improved, but tire weight increases
Solution Approach 1:
The patent extracts the reinforcement function from traditional extensive rubber and separate reinforcing member constructions, concentrating it into the apex elements. By taking out only the essential reinforcement function and implementing it through these focused apex elements, the design achieves necessary bead strength without the weight penalty of comprehensive additional reinforcing members throughout the bead portion.
Solution Approach 2:
The reinforcement function is segmented into discrete apex elements rather than using continuous or distributed reinforcing members. This segmentation allows precise placement of strength-providing components only where structurally necessary, eliminating redundant weight from areas that do not require additional reinforcement, thus improving strength-to-weight ratio.
Data Source
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AI summary
A pneumatic radial tire (1) comprising a tire carcass is disclosed. The tire (1) comprises a tread portion comprising a tread (3) disposed on the tire carcass; a pair of sidewall portions (4) adjacent to the tread portion;=a carcass ply (5, PC) extending circumferentially about the tire (1) and exhibiting two ply ending portions (20), wherein each ply ending portion (20) comprises a first ply contact section (21, Si) adjacent to a ply turn-up section (22, ST), said ply turn-up section (22, ST) being adjacent to a second ply contact section (23, S2), said second ply contact section (23, S2) forming or including the end of the ply ending portion (20); and a pair of bead portions adjacent to the sidewall portions (4). Each bead portion comprises a bead core (7), one or more apex elements (6) and one of the two ply ending portions (20) of said carcass ply (5, PC). In each bead portion, the ply ending portion (20) comprised therein forms a sealed enclosure (30) containing the bead core (7), said sealed enclosure (30) exhibiting a ply-to-ply contact section (11, Sc) formed by the first ply contact section (21, Si) and the second ply contact section (22, S2), and further exhibiting a surrounding section formed by the ply turn-up section (22, ST). In each bead portion, at least one apex element (6, EA) of the one or more apex elements (6) is located axially outwards from the ply-to-ply contact section (11, Sc) and at least a portion of the axially inward surface of said at least one apex element (6, EA) is in direct contact with an axially outward surface of the ply-to-ply contact section (11, Sc).