Pneumatic Tire Curved Carcass Weight Reduction
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Solution Overview
Problem
Existing pneumatic tire designs face challenges in reducing weight while maintaining rigidity and durability, particularly in the tread and side regions, with complex manufacturing methods and ineffective reinforcement from multiple carcass layers.
Innovation Solution
A pneumatic tire with a curved carcass structure featuring a double layer carcass layer where the cord angle changes continuously from the tread central region to the side regions, sharing the function of a belt layer and minimizing non-reinforcing portions, combined with a single belt layer and intermediate rubber layer for enhanced rigidity and durability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of moving object
If the thickness of rubber is reduced in cap tread and sides to reduce weight, then weight is reduced, but wear resistance and durability deteriorate
Solution Approach 1:
The carcass cord angle is varied locally across different regions of the tire. In the tread region, the cord angle is set to provide rigidity and support, while in the side regions, the cord angle is adjusted to maintain flexibility and durability. This localized optimization allows the tire to achieve weight reduction without compromising wear resistance and durability in critical areas.
Solution Approach 2:
The tire employs a composite structure combining the carcass layer with varying cord angles and the belt layer. This composite design allows different regions of the tire to have optimized material properties - the carcass layer provides structural support with region-specific cord angles, while the belt layer adds rigidity to the tread region, together achieving weight reduction while maintaining overall durability.
2Strength
If multiple carcass layers are used to reinforce the space between bead cores, then reinforcement is improved, but the end portions of carcass layers do not substantially function as reinforcing materials, reducing effectiveness
Solution Approach 1:
The carcass layer is divided into an inner layer and an outer layer, with each layer having optimized cord angles for different regions. The inner layer has cords extending to the ground contact edge, while the outer layer provides additional reinforcement. This segmentation allows each layer to function effectively throughout its length, eliminating the problem of non-functional end portions.
Solution Approach 2:
The cord angle parameter is changed between the inner and outer layers of the carcass, and between different regions (tread vs. side regions). This parameter variation ensures that each layer contributes effectively to reinforcement across the entire tire structure, maximizing the functional effectiveness of all carcass layer portions.
3Weight of moving object
If a single belt layer is used instead of multiple belt layers, then weight is reduced, but rigidity may be compromised
Solution Approach 1:
The single belt layer is designed with locally optimized properties, including region-specific cord angles and strategic positioning. The belt cords are arranged to provide maximum rigidity where needed in the tread region, compensating for the reduction from using only a single layer instead of multiple layers, thereby achieving weight reduction without compromising essential rigidity.
Data Source
AI summary
Provided is a pneumatic tire. One terminal of a carcass layer extends to a ground contact edge of a tread portion positioned on an opposite side with respect to a tire center line as a reference. The carcass layer has a double layer structure including an inner layer positioned inward in a tire radial direction in a tread region and an outer layer positioned outward in the tire radial direction of the inner layer in the tread region. A cord angle in the carcass layer in a tread central region with respect to a tire circumferential direction is different from a cord angle in at least one of the inner layer and the outer layer of the carcass layer in a side region with respect to the tire circumferential direction.