Pneumatic Tire Bead Core Elongation Fitting Pressure
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Solution Overview
Problem
Pneumatic tires face challenges in reducing fitting pressure during mounting, which increases the risk of bead portion damage and reduces durability, while maintaining a sufficient tightening force to prevent rim misalignment and detachment.
Innovation Solution
Incorporating second bead wires with greater elongation than first bead wires in the innermost side of the bead core, specifically designed to reduce fitting pressure by local elongation during mounting, while maintaining the tightening force with first bead wires.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the tightening force of the bead core is increased by increasing the width or number of bead wires, then rim misalignment and rim detachment are restrained, but fitting pressure increases excessively causing bead portion damage
Solution Approach 1:
The bead core is designed with non-uniform bead wire distribution, concentrating bead wires with smaller diameters (greater elongation) in the innermost side portion and bead wires with larger diameters (smaller elongation) in the outer side portion. This local differentiation allows the innermost portion to reduce fitting pressure through greater elongation while the outer portion maintains tightening force with smaller elongation, resolving the contradiction between these two requirements.
Solution Approach 2:
The invention changes the parameter of bead wire diameter distribution within the bead core, specifically varying the diameter of individual bead wires or groups of bead wires across different radial positions. By controlling the diameter parameter to create smaller diameter wires on the innermost side and larger diameter wires on the outer side, the invention achieves different elongation characteristics in different regions, thereby simultaneously reducing fitting pressure and maintaining tightening force.
2Ease of operation
If the number of bead wires in the innermost side portion is increased to reduce fitting pressure, then the bead portion can move over the hump more easily, but the tightening force may be reduced
Solution Approach 1:
The bead core structure implements local quality differentiation by assigning different bead wire characteristics to different radial positions. The innermost side portion contains bead wires optimized for elongation (smaller diameter) to facilitate mounting, while the outer side portion contains bead wires optimized for strength (larger diameter) to maintain tightening force, thus resolving the contradiction between ease of operation and strength.
Solution Approach 2:
The bead core functions as a composite structure combining bead wires with different diameter specifications in a systematic arrangement. This composite configuration allows the integration of multiple material properties (different elongation characteristics) within a single functional component, enabling simultaneous achievement of reduced fitting pressure and maintained tightening force.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution effectively reduces fitting pressure, enhances workability and durability of the bead portion, and prevents rim misalignment and detachment by maintaining a sufficient tightening force.
Implementation Method 1
a second bead wire having an elongation α, represented by equation (1), which is greater than an elongation of a first bead wire
Data Source
AI summary
A pneumatic tire has bead cores provided in bead portions. The bead cores include a first bead wire, and a second bead wire having an elongation α, where α(%)=ΔL/L×100, L is a length of each of the bead wires under no load, and ΔL is an elongation amount obtained when a unit load is applied. The elongation α of the second bead wire is greater than an elongation of the first bead wire. The number of the second bead wire provided in an innermost side portion in a tire radial direction is at least one.