Endless Belt Tire Structure for Uniform Tread Rigidity
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Solution Overview
Problem
Pneumatic tires with endless belts experience uneven wear due to differences in circumferential rigidity between the tire's central and edge regions, which are caused by the orientation change of belt cords at the tire width ends.
Innovation Solution
The tire design incorporates an endless belt with rubber-coated cords that change direction inward in the tire width direction and extend in a zigzag manner, with specific geometric relationships between the cord inclination angles and lengths to minimize rigidity differences.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the belt cord changes direction inward at both ends in the tire width direction, then the durability is improved by preventing separation between adjacent rubber members, but the circumferential rigidity becomes uneven causing tread wear
Solution Approach 1:
The patent applies local quality by differentiating the belt cord configuration between the central portion and both end portions of the tire width direction. Specifically, the belt cord inclination angle θ is set to 5° or more and 30° or less at the end portions, while at the central portion the inclination angle is set to 0° or more and 5° or less. This localized variation in cord angle creates different rigidity characteristics in different regions, preventing excessive rigidity at the ends while maintaining sufficient rigidity at the center, thereby eliminating uneven tread wear while preserving the separation-prevention function at the ends.
2Reliability
If the belt cord extends in a zigzag manner, then the endless belt structure is formed preventing cut end exposure, but the rigidity difference between ends and center increases
Solution Approach 1:
The patent applies parameter changes by precisely controlling the belt cord inclination angle θ as a key geometric parameter. At the end portions where the cord changes direction inward, the inclination angle is set to 5°≤θ≤30°, while at the central portion the inclination angle is set to 0°≤θ≤5°. This parameter differentiation modifies the rigidity distribution across the tire width, reducing the rigidity at the ends and increasing it at the center, thereby achieving uniform rigidity across the tread surface while maintaining the endless belt structure.
Data Source
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AI summary
A pneumatic tire of the present disclosure includes an endless belt with a rubber coated cord, formed by coating a belt cord with rubber, extending in a zigzag manner in the tire circumferential direction. In a developed view of the endless belt, an intersection formed by the belt cord intersecting at two bent portions, adjacent in the tire circumferential direction, of the rubber coated cord is designated as T, and a length L in the tire circumferential direction between two intersections T adjacent in the tire circumferential direction, a width W of the belt cord, and an inclination angle θ1 of the belt cord relative to the tire circumferential direction at inclined extending portions of the rubber coated cord satisfy the relationships 5° < θ1 ≤ 10°, and L < (3W/tan(θ1 - 2°)), or 10° < θ1 ≤ 45°, and L < (3W/tan(θ1 - 5°)).