Pneumatic Tire Bead Reinforcement Layout for Stiffness and Stability
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Solution Overview
Problem
Existing pneumatic tires face challenges in achieving desired reinforcing effects on vertical, lateral, and forward/backward stiffness due to close proximity of bead reinforcing cord layers, which affects driving force and steering stability.
Innovation Solution
A pneumatic tire design with a carcass and bead reinforcing layer structure, including a first carcass ply and a bead reinforcing ply arranged at specific angles, with distinct portions folded around the bead core, ensuring proper tension and distribution of cord tensions to enhance stiffness and stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of moving object
If the bead reinforcing cord layer is designed with first and second portions close to each other to reduce weight, then weight reduction is achieved, but the cord tensions act mutually and the desired reinforcing effect on stiffness cannot be achieved
Solution Approach 1:
The bead reinforcing cord layer is segmented into a first portion and a second portion with distinct functions. The first portion is disposed on the axially outside of the carcass ply main portion to provide lateral stiffness, while the second portion is disposed on the axially inside of the carcass ply turnup portion to provide vertical stiffness. This segmentation allows each portion to independently contribute to different stiffness requirements without mutual interference of cord tensions.
Solution Approach 2:
The invention introduces axial positioning as a critical dimension for bead reinforcing cord arrangement. By specifying that the first portion is axially outside and the second portion is axially inside with a distance of 5mm or more between them, the design utilizes the axial dimension to separate the reinforcing functions, enabling independent tension action in different directions (lateral vs vertical) and achieving comprehensive stiffness enhancement.
2Weight of moving object
If the bead reinforcing cord layer is designed with portions close to each other to achieve lightweight, then weight reduction is achieved, but driving force and steering stability cannot be improved
Solution Approach 1:
The bead reinforcing cord layer is divided into functionally distinct first and second portions positioned at different axial locations. This segmentation enables the first portion to primarily support lateral forces during steering while the second portion supports vertical forces during driving, thereby improving both steering stability and driving force independently without requiring the portions to be close together.
Solution Approach 2:
Different regions of the bead reinforcing cord layer are assigned different functional qualities: the first portion (axially outside) is optimized for lateral stiffness to improve steering stability, while the second portion (axially inside) is optimized for vertical stiffness to improve driving force. This local differentiation of functional quality allows simultaneous improvement of both reliability aspects.
Data Source
Figure 1
Figure 2
AI summary
A pneumatic tire 1 comprises a bead portion 4, a carcass 6, a bead reinforcing layer 9, and a bead apex rubber 8. The carcass 6 comprises a first carcass ply 6A of carcass cords arranged at an angle of 60 to 90 degrees with respect to the tire circumferential direction. The bead reinforcing layer 9 comprises a first reinforcing ply of bead reinforcing cords arranged at an angle of 60 to 90 degrees with respect to the tire circumferential direction. The first carcass ply 6A is composed of a main portion 6a and a turnup portion 6b continued from the main portion 6a. The first reinforcing ply 9A comprises a first portion 9a and a second portion 9b continued from the first portion 9a. The radially outer end 9be of the second portion 9b is located on the axially outer side of the bead apex rubber 8 and on the radially inner side of the radially outer end 8e of the bead apex rubber 8.