Concave Bead Lip Geometry for Tire Rim Flange Abrasion
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Solution Overview
Problem
Pneumatic vehicle tires with rim flanges experience abrasion, especially in humid climates with sand, due to relative movements between the bead strip and rim flange, leading to adverse abrasion symptoms on aluminum rims.
Innovation Solution
A pneumatic vehicle tire with a concavely curved bead lip surface having a radius of curvature R2 less than 9.5 mm, allowing for a press fit and sealing function when mounted on a rim with a rim flange radius R1 of at least 9.5 mm, reducing abrasion by particles between the bead area and rim flange.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional bead lip design is used, then the tire structure is simple, but rim flange abrasion occurs due to relative movement between bead and rim flange
Solution Approach 1:
The bead lip surface is designed with a concave curvature having a radius R2 less than the rim flange radius R1, creating a press-fit condition that eliminates relative movement between the bead and rim flange. This curved surface geometry transforms the flat contact interface into a conforming joint that prevents sand entrapment and abrasion while maintaining structural simplicity.
2Reliability
If the bead lip surface is made flat, then manufacturing is easier, but sealing function is insufficient leading to sand entrapment and abrasion
Solution Approach 1:
The concave curved surface of the bead lip creates a natural sealing interface against the rim flange through geometric conformity. The curvature radius R2 being less than R1 ensures continuous contact pressure distribution that prevents sand entrapment and maintains sealing effectiveness throughout the tire rolling cycle.
Solution Approach 2:
By changing the geometric parameter of the bead lip surface from flat to concave with a specific curvature radius relationship (R2 < R1), the sealing performance is significantly improved. This parameter modification creates inherent sealing through the press-fit condition without requiring additional sealing components or complex manufacturing processes.
3Strength
If more material is used in the bead lip, then structural strength increases, but weight and rolling resistance increase
Solution Approach 1:
The concave curved bead lip surface design allows for optimized material distribution that provides sufficient structural strength with minimal material usage. The geometric form creates inherent structural efficiency by distributing stresses through the curved surface, enabling the use of thinner or less material while maintaining the required mechanical properties.
Data Source
Figure 1
Figure 2~3
AI summary
A vehicle pneumatic tire (10) suitable for mounting on a rim (11) with a curved rim flange area (12) having a rim flange radius R1 of at least 9.5 mm. The invention further relates to a vehicle wheel comprising a corresponding rim and a tire according to the invention mounted on the rim. The object of the present invention is to enable improved durability of the rim flange with regard to abrasion. This is achieved by arranging a bead lip (9) circumferentially around the circumference of the tire sidewall at least on the axial outer side (A), by having a bead lip surface (13) on the axial outer side (A) that is intended to bear wholly or partially on the curved rim flange area (12), and by having a concavely curved bead lip surface (13) when viewed in the tire cross-section, with a radius of curvature R2 of R2 < 9.5 mm.