Tire Bead Structure Using Carcass Ply Tilt for Low Rolling Resistance
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Solution Overview
Problem
Current pneumatic tire designs face challenges in reducing rolling resistance while maintaining desired stiffness, particularly at the bead portion, which affects steering stability and durability.
Innovation Solution
The design incorporates a carcass ply with a main body portion that extends between tire cores, featuring a tilt angle of 40° to 60° relative to the axial direction, a smaller apex with a length of 10-15 mm, and a reinforcing layer with specific elastic properties to balance rolling resistance and stiffness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a small apex (10-15 mm length) is used for the bead, then weight is reduced and rolling resistance is reduced, but stiffness becomes insufficient and steering stability decreases
Solution Approach 1:
The patent changes the geometric parameters of the bead structure by reducing the apex length to 10-15 mm and optimizing the tilt angle of the main body portion to 40°-60° relative to the axial direction. These parameter changes reduce the volume and weight of the hard crosslinked rubber apex, thereby reducing rolling resistance while maintaining sufficient stiffness through optimized geometry
Solution Approach 2:
The patent introduces dynamic characteristics by creating an inflection point in the tilt of the main body portion, where the tilt angle transitions from a large portion near the core to a small portion at the outer edge. This dynamic tilt profile allows the structure to adapt to loading conditions, providing stiffness when needed while reducing overall material volume for lower rolling resistance
2Weight of moving object
If a small apex (10-15 mm length) is used for the bead, then weight is reduced, but steering stability decreases due to insufficient stiffness
Solution Approach 1:
The patent optimizes geometric parameters including apex length (10-15 mm) and tilt angle (40°-60°) to achieve the lightest possible bead structure that maintains adequate steering stability through careful parameter selection rather than increasing mass
Solution Approach 2:
The patent employs curved surfaces in the apex and main body portion design, using the inflection point in the tilt profile to create a smooth transition that maintains structural integrity and stiffness distribution, preventing sharp corners that would concentrate stress and reduce stability
Data Source
AI summary
In a tire 22, a length from a center PM in an axial direction of a boundary 60 between a core 48 and an apex 50 to an outer edge PA of the apex 50 is not less than 10 mm and not greater than 15 mm. In a state where the tire 22 is mounted on a normal rim and an internal pressure of the tire 22 is adjusted to 10% of a normal internal pressure, a main body portion 54 of a carcass ply 52 extending along an inner surface 62 of the apex 50 is tilted relative to the axial direction, and an angle of the main body portion 54 relative to the axial direction is not less than 40° and not greater than 60°.