Low-Aspect-Ratio Pneumatic Tire Belt Structure for Edge Durability
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Solution Overview
Problem
Off-the-road tires with low aspect ratios experience increased load index and deflection, leading to separation of peripheral rubber at the end portions of the belt plies, which compromises belt edge durability.
Innovation Solution
A pneumatic tire design featuring a carcass layer with a cord angle of 80° to 100°, a belt layer comprising a first reinforcing belt, a narrower second reinforcing belt, and an auxiliary belt with a cord angle of 55° to 70°, strategically positioned between the carcass layer and the first reinforcing belt to enhance belt edge durability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the aspect ratio is lowered to improve applied load capacity, then the load capacity increases, but the deflection amount increases and peripheral rubber separation occurs at belt edge
Solution Approach 1:
The belt layer is segmented into multiple reinforcing belts with different cord angles and widths. The first reinforcing belt has a cord angle of 10° to 25° and extends across the full width, while the second reinforcing belt has a cord angle of 35° to 50° and is narrower, positioned toward the tire center. This segmentation allows each belt to perform specific functions in resisting different stress components, improving overall belt edge durability without compromising load capacity.
Solution Approach 2:
Different regions of the belt layer are given different properties through the use of reinforcing belts with varying cord angles and widths. The first reinforcing belt with smaller cord angle provides stability at the shoulders, while the second reinforcing belt with larger cord angle provides strength at the center. This local differentiation of properties allows the tire to maintain high load capacity while preventing peripheral rubber separation at critical belt edge regions.
2Length of stationary object
If the aspect ratio is lowered to maintain outer diameter, then the outer diameter is maintained, but the load index increases causing increased deflection
Solution Approach 1:
The belt layer structure is designed to dynamically respond to different loading conditions. The first reinforcing belt with smaller cord angle becomes more effective under radial loads, while the second reinforcing belt with larger cord angle provides support during lateral deflection. This dynamic interaction between differently oriented belts allows the tire to maintain its outer diameter while reducing excessive deflection under load.
Data Source
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AI summary
The pneumatic tire (1) includes a carcass layer (13), a belt layer (14) disposed on an outer side of the carcass layer (13) in a radial direction, and a tread rubber disposed on an outer side of the belt layer (14) in the radial direction. Additionally, the carcass layer (13) has a cord angle of 80 ° or more and 100 ° or less. Additionally, the belt layer (14) is formed by layering a first reinforcing belt (141), a second reinforcing belt (142) that is narrower than the first reinforcing belt (141), and an auxiliary belt (145) that is spaced apart from a tire equatorial plane (CL) and disposed between the carcass layer (13) and the first reinforcing belt (141). Additionally, the first reinforcing belt (141) and the second reinforcing belt (142) have cord angles of 11 ° or more and 30 ° or less, and the auxiliary belt has a cord angle of 55 ° or more and 70 ° or less, wherein a distance De5 from the tire equatorial plane (CL) to an outer end portion of the auxiliary belt (145) in a tire width direction has a relationship 0.75 ≤ De5/De1 ≤ 0.99 with respect to a distance De1 from the tire equatorial plane (CL) to an end portion of the first reinforcing belt (141), wherein a distance De5' from the tire equatorial plane (CL) to the inner end portion of the auxiliary belt (145) in the tire width direction has a relationship 0.05 ≤ De5'/De5 ≤ 0.30 with respect to the distance De5.