Heavy Duty Tire Flexible Zone Bead Durability
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Solution Overview
Problem
Heavy duty pneumatic tires face a challenge in balancing rim mountability and bead durability, as increasing bead rigidity to enhance durability can compromise ease of mounting on a rim, and vice versa.
Innovation Solution
A heavy duty pneumatic tire design with a flexible zone ratio of 0.25 to 0.4 in the radial direction to the cross-sectional height of the carcass, featuring an arc-shaped body portion in the flexible zone, and specific dimensions for the bead and turned-up portions to maintain appropriate flexibility and rigidity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an apex having a height is employed to increase bead rigidity, then bead durability is improved, but rim mountability is reduced
Solution Approach 1:
The patent applies local quality by creating a flexible zone with specific structural characteristics (arc-shaped body portion with controlled radius ratio) in the radial direction, while maintaining apex height for bead rigidity. This localized structural modification allows the side portion to have enhanced flexibility for mounting while the bead apex maintains sufficient rigidity for durability.
Solution Approach 2:
The patent introduces dynamics by making the body portion shape adaptable through the arc configuration with specific radius ratios. This allows the structure to dynamically adjust during mounting operations, providing the necessary flexibility for rim mounting while maintaining structural integrity for bead durability under load conditions.
2Reliability
If the side portion is made rigid to suppress bead movement, then bead durability is improved, but ease of mounting is reduced
Solution Approach 1:
The patent applies local quality by differentiating the structural properties in the radial direction through the flexible zone design. The body portion with arc shape and controlled radius ratio provides localized flexibility in the side portion area, while other regions maintain the rigidity needed for bead durability.
Solution Approach 2:
The patent segments the tire structure into distinct functional zones: the flexible zone with arc-shaped body portion for mounting operations, and the apex region for durability. This segmentation allows each zone to be optimized independently for its specific function.
Data Source
Figure 1
Figure 2
AI summary
The aspect ratio of this tire 2 is not greater than 75%. The tire 2 includes: a carcass 12 extending from one bead 8 to the other bead 8; a belt 14 located between a tread 4 and the carcass 12; and a cushion layer 16 located between an end 54 of the belt 14 and the carcass 12. Each bead 8 includes a core 34 and an apex 36. The zone from the inner end of the cushion layer 16 to the outer end of the apex 36 is a flexible zone. The ratio of a length F in the radial direction of the flexible zone to a cross-sectional height A of the carcass 12 is not less than 0.25 and not greater than 0.4.