Low-Profile Pneumatic Tire Belt Ply Layout for Belt-End Durability
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Solution Overview
Problem
Pneumatic tires for small-size vehicles face increased strain in outer end portions of the belt layer, leading to damage such as separation of the belt ply, which is a challenge in ensuring both high load bearing performance and maximizing vehicle cabin space.
Innovation Solution
A pneumatic tire design with specific rim and cross-sectional ratios, incorporating a belt layer with first and second belt plies covered by edge cover rubbers, and optionally a third rubber and band layer, to inhibit damage and enhance durability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the tire size is reduced to maximize vehicle cabin space, then the vehicle cabin space is increased, but the strain in outer end portions of the belt layer increases leading to belt layer damage
Solution Approach 1:
The patent applies local quality by providing different structural characteristics to different regions of the belt layer. Specifically, the outer end portions of the belt plies are reinforced with edge cover rubbers and positioned over rounded portions of the rim, while the central portions maintain standard construction. This localized reinforcement addresses the specific problem of strain concentration at outer end portions without affecting the overall tire size or cabin space.
Solution Approach 2:
The patent implements beforehand cushioning by placing edge cover rubbers at the outer end portions of the belt plies before damage can occur. These edge cover rubbers, along with the rounded rim portions, serve as protective elements that cushion and distribute the strain that would otherwise concentrate at the vulnerable outer end portions, preventing belt layer separation and damage.
2Strength
If the rim width to tire cross-sectional width ratio is increased to improve load bearing performance, then the load bearing performance is improved, but the tire structure becomes more constrained
Solution Approach 1:
The patent applies parameter changes by optimizing the rim width to tire cross-sectional width ratio within a specific range (0.78 to 0.99). This parameter optimization allows the tire to achieve improved load bearing performance while maintaining reasonable structural flexibility. The rounded portion radius ratio (Rr/Rw) is also optimized within specific ranges to balance structural requirements with performance goals.
Data Source
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AI summary
A pneumatic tire which has a specific tire size and can inhibit damage to a belt layer is provided. The pneumatic tire is mounted and used on a rim R. The rim R has a rim diameter RD of 12 to 17 inches. A ratio SH/SW of a tire cross-sectional height SH to a tire cross-sectional width SW is 0.30 to 0.45. A ratio RW/SW of a rim width RW to the tire cross-sectional width SW is 0.78 to 0.99. The pneumatic tire includes a tread portion 2. A belt layer 7 is disposed in the tread portion 2. The belt layer 7 includes a first belt ply 11, and a second belt ply 12 disposed outward of the first belt ply 11 in a tire radial direction. A maximum rubber gauge between the first belt ply 11 and the second belt ply 12 is 1.0 to 3.0 mm.