Tire Tread Cavity Protuberances to Limit Stone-Trap Cracking
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Solution Overview
Problem
Existing motor vehicle tires with stone-ejecting means suffer from premature deterioration due to mechanical stresses, leading to crack initiation and reduced durability, while maintaining effective drainage and wear resistance.
Innovation Solution
The design incorporates two protuberances within the external cavity of the tire tread, inclined and spaced to decouple during running, optimizing stone ejection and reducing crack generation, with a distance between protuberances less than 10% of the cavity width to enhance durability and drainage performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If means for ejecting stones are implemented in the tread, then stone trapping is reduced, but mechanical stresses cause crack initiation and premature deterioration
Solution Approach 1:
The means for ejecting stones is segmented into multiple independent protuberances (at least two) disposed within the external cavity. Each protuberance can move independently, which reduces the concentration of mechanical stresses and prevents crack propagation that would occur in a single monolithic structure. This segmentation allows the ejection function to be maintained while improving durability.
Solution Approach 2:
The protuberances are designed to be movable rather than fixed, allowing them to dynamically adjust during tire operation. This dynamic capability enables the protuberances to accommodate mechanical stresses through independent movement, reducing stress concentration and preventing crack initiation while maintaining the stone ejection function.
2Productivity
If protuberances are spaced closely (d ≤ 10% of cavity width), then stone ejection effectiveness is improved, but structural integrity may be compromised
Solution Approach 1:
The closely spaced protuberances are designed as separate, independent elements rather than a continuous structure. This segmentation allows each protuberance to deflect independently under load, maintaining structural integrity even when spaced closely for effective stone ejection. The independent movement capability prevents stress concentration between the closely spaced elements.
Solution Approach 2:
The distance between protuberances is optimized to be less than or equal to 10% of the external cavity width. This parameter optimization balances the competing requirements of stone ejection effectiveness (requiring close spacing) and structural integrity (requiring sufficient material between elements). The specific dimensional relationship ensures both functions are achieved.
Data Source
AI summary
A tread (12) for a tire (10) which has a tread surface intended to contact a road surface during running. The tread (12) has at least one cavity opening onto the tread surface when new, called external cavity (14), which has length L, width W and central plane P. The external cavity (14) has bottom (16) and at least two opposite lateral walls (18a, 18b) extending from bottom (16) and a mechanism (20) for ejecting stones during running, which has two protuberances (22a, 22b) from bottom (16) of external cavity, which are disposed at least partially opposite one another at a distance d. Each protuberance (22a, 22b) is inclined respectively from a lateral wall (18a, 18b) of the external cavity (14) towards the central plane P. The distance d between the two protuberances (22a, 22b) is less than or equal to 10% of width W of external cavity (14).