Tire Sidewall Rib Structure for Lower Mass and Cut Resistance
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Solution Overview
Problem
Tires used on construction sites face challenges in reducing mass without compromising resistance to attacks from sharp objects, such as metal rods, while maintaining durability and resistance to damage.
Innovation Solution
A tire design featuring a carcass reinforcement with a crown reinforcement and tread, incorporating circumferential protuberances on the sidewalls made of a specific rubber composition, including anti-ozone wax, which reduces sidewall thickness while maintaining resistance and durability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of moving object
If the sidewall thickness is reduced to decrease tire mass, then the tire mass is reduced, but the resistance to attacks from sharp objects and durability are compromised
Solution Approach 1:
The sidewall is segmented into multiple functional zones: the main sidewall with reduced thickness for weight reduction, and circumferential protuberances with increased thickness for protection. This segmentation allows different parts of the sidewall to have different thicknesses optimized for their specific functions.
Solution Approach 2:
The protuberances are positioned at specific locations on the sidewall where protection is most needed. The rubber composition is locally modified in the protuberances by adding anti-ozone wax and other protective agents, creating local quality enhancement without increasing overall sidewall thickness or mass significantly.
2Strength
If protective ribs are added to the sidewall to increase resistance to sharp objects, then the resistance to attacks is improved, but the tire mass increases
Solution Approach 1:
Instead of uniformly thickening the entire sidewall, the invention applies protective protuberances only in specific circumferential locations where protection is most needed. This partial action provides sufficient protection while minimizing the additional mass compared to uniform thickening.
Solution Approach 2:
The protuberances use a composite rubber composition that includes anti-ozone wax, zinc oxide, and other protective agents in specific concentrations. This composite material provides enhanced protective properties per unit mass, reducing the overall mass increase compared to using conventional rubber throughout.
3Reliability
If the sidewall is thickened to improve durability and resistance to damage, then the durability is improved, but the tire mass increases
Solution Approach 1:
The sidewall structure is segmented into the main thin-walled portion for weight reduction and localized thickened protuberances for durability. This segmentation allows the tire to achieve high durability at critical points without the penalty of uniformly thick walls throughout.
Solution Approach 2:
The rubber composition parameters are changed locally in the protuberances by adjusting the concentrations of anti-ozone wax (5-15 parts by weight per 100 parts of rubber), zinc oxide (3-8 parts), and other protective agents. These parameter changes enhance durability without requiring increased thickness.
Data Source
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AI summary
The invention relates to a tire (1) having a carcass reinforcement (2) topped by a crown reinforcement (3) which itself is topped by a tread (7), said tread being connected to two beads (6) via two sidewalls (4), each sidewall having an outer surface (40), at least one of said sidewalls comprising at least two circumferential projections (5a, 5b, 5c), each sidewall (4) comprising an equator point (E) situated on the outer surface of the sidewall and radially at the same position than the axially outermost point (20) of the carcass reinforcement (2) in a non-loaded configuration. Each circumferential projection (5a, 5b, 5c) is delimited by a radially upper wall (51), a radially lower wall (52) and a connecting wall (53) situated between the radially upper wall (51) and the radially lower wall (52). Each circumferential projection is characterized in that: the connecting wall (53) is substantially parallel to the carcass reinforcement when viewed axially relative to said connecting wall (53); the radially upper wall (51) has a substantially frustoconical shape; the height (H) of each circumferential projection (5a, 5b, 5c), which is measured according to a direction substantially perpendicular to the carcass reinforcement (2) from said outer surface (40), is more than at least 0.8 times the total thickness (T) of the sidewall measured at the equator (E) and 4 mm and is inferior to at most 1.6 times the total thickness (T) and 8 mm; in the meridian plane at the center of the contact region of the tire in a deployed configuration, the angle (α), which is formed by the radially exterior wall (51) with the radial direction, is larger than 95° for the radially outermost projection (5a); the innermost radial position of the connecting wall (53) of the radially innermost projection (5c) is situated radially outside of the equator point (E).