Pneumatic Tire Bead Core Asymmetric Twisting
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Solution Overview
Problem
Pneumatic tires with heat-shrinkable carcass cords tend to experience increased tension during vulcanization, leading to damage on the inner liner and reduced durability due to the carcass cord biting into it.
Innovation Solution
The tire design features bead cores with inner and outer cores having bead cords wound in opposite directions, allowing the carcass ply to move radially outward and untwist, reducing tension on the carcass cord and preventing it from biting into the inner liner.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If a heat-shrinkable carcass cord is used to achieve dimension stability during vulcanization, then the tire maintains good shape and size control, but the carcass cord tension increases and bites into the inner liner causing damage
Solution Approach 1:
The bead core is divided into two separate parts: an inner core and an outer core, with the carcass ply end positioned between them. This segmentation allows independent control of each core's bead cord twisting direction, enabling the inner and outer cores to have opposite twisting directions that counterbalance each other during carcass cord shrinkage
Solution Approach 2:
The inner core and outer core are designed with asymmetric twisting directions relative to each other. When viewed from the axial outward direction, one core has a twisting direction that causes the carcass ply to move radially outward, while the other core has the opposite twisting direction. This asymmetric design creates opposing forces that prevent excessive tension concentration
2Stability of the object's composition
If the carcass cord tension is increased during vulcanization to maintain tire shape, then dimension stability is improved, but the inner liner becomes damaged due to cord biting
Solution Approach 1:
The heat-shrinkable property of the carcass cord, which causes harmful biting into the inner liner, is converted into a beneficial effect. By designing the bead cords with opposite twisting directions, the shrinkage force is distributed and redirected to push the carcass ply radially outward between the inner and outer cores, preventing concentration of tension at any single point and eliminating the biting effect on the inner liner
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
This design enhances the durability of the tire by preventing excessive tension on the carcass cord, thereby reducing the likelihood of damage to the inner liner and improving overall tire stability and longevity.
Implementation Method 1
untwisting occurs on each outermost layer of the bead cords of the respective inner core and the outer core so that the carcass ply moves easily radially outwardly
Implementation Method 2
a material having a heat shrinkable property may be used. Such a carcass cord shrinks by heat during vulcanization
Data Source
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AI summary
Provided is a pneumatic tire which is configured so as to prevent carcass cords from biting into an inner liner, thereby improving the durability performance of the tire. A pneumatic tire (1) is provided with a carcass (6) which comprises a carcass ply (11) extending from a tread (2) through side walls (3) to the bead cores (5) of bead sections (4), the bead cores (5) each including an inner core (14) and an outer core (15). The carcass ply (11) is sandwiched between the inner cores (14) and the outer cores (15). Each of an inner core (14) and an outer core (15) includes a bead cord (16) which is wound at least one turn in the circumferential direction of the tire. Each of the bead cords (16) includes an outermost layer (18) formed by twisting filaments (17) together. In at least one bead section, the outermost layer (18) of the bead cord (16) of each of the inner core (14) and the outer core (15) is twisted in the direction which allows the carcass ply (11) to easily move to the outside in the radial direction of the tire from between the inner core (14) and the outer core (15).