Endless Belt Cord Layout for Uniform Tire Circumferential Rigidity
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Solution Overview
Problem
The difference in circumferential rigidity between the ends and central portions of an endless belt in a pneumatic tire leads to uneven wear on the tire tread surface.
Innovation Solution
The pneumatic tire incorporates an endless belt with rubber-coated cords that have bent portions at the ends and inclined extending portions towards the center, configured to reduce the difference in circumferential rigidity by optimizing the inclination angles and length between intersections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an endless belt is used with belt cords extending in the tire circumferential direction at the ends, then the tire durability is improved by preventing separation between adjacent rubber members, but the circumferential rigidity at the ends becomes higher than at the central portion causing uneven wear on the tire tread surface
Solution Approach 1:
The patent applies local quality by making the belt cord configuration position-dependent. At the central portion of the tire width, belt cords extend in the tire circumferential direction to provide high circumferential rigidity. At the ends in the tire width direction, belt cords are oriented inward in the belt plane direction to reduce circumferential rigidity. This spatial variation in cord orientation creates local differences in mechanical properties that compensate for the inherent rigidity distribution, achieving uniform overall circumferential rigidity across the tire width while maintaining the endless belt structure for durability.
2Stability of the object's composition
If belt cords are oriented inward in the belt plane direction at both ends in the tire width direction, then the circumferential rigidity at the ends is reduced to match the central portion, but the structural complexity of the belt increases
Solution Approach 1:
The patent merges multiple belt cord layers with different orientations into a single integrated endless belt structure. The first belt cord layer and second belt cord layer are combined in a staggered arrangement where cords from different layers interlock. This merging approach achieves the desired variable rigidity profile through the combined structural behavior of multiple layers rather than requiring complex single-layer configurations, thereby reducing overall structural complexity while maintaining the ability to control circumferential rigidity distribution.
Data Source
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<(3 W/tan(θ1−2°)), or 10°<θ1≤45°, and L<(3 W/tan(θ1−5°)).