Pneumatic Tire Bead Vent Lines Reduce Fitting Pressure
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Solution Overview
Problem
Conventional pneumatic tires face challenges in achieving a well-balanced adjustment of appearance quality, bead unseating resistance, and fitting pressure, often resulting in high fitting pressure due to heel face catching by the rim hump, reduced bead unseating resistance with increased core diameter or reduced wire winding, and degraded appearance with larger heel face radius.
Innovation Solution
The pneumatic tire design includes a bead portion with a ring-shaped core, an apex radially outward of the core, a seat face, a flange face, a heel face with an arc contour radius between 8mm and 15mm, and multiple vent lines projecting from the heel face, along with a saw cut connecting adjacent vent lines, to inhibit heel face catching and balance fitting pressure and bead unseating resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the radius of the arc representing the contour of the heel face is increased to reduce fitting pressure, then the bead portion is less likely to be caught by the hump, but air discharge between the mold and bead portion is inhibited, degrading appearance quality
Solution Approach 1:
The heel face is segmented into multiple regions by introducing vent lines that extend in the circumferential direction. These vent lines create channels for air discharge, allowing the heel face to have a larger radius (8-15mm) for reduced fitting pressure while maintaining appearance quality through controlled air escape paths.
Solution Approach 2:
The vent lines are strategically positioned at specific locations on the heel face where air accumulation occurs during tire production. This localized feature allows air discharge without affecting the overall contour radius of the heel face, enabling both low fitting pressure and good appearance quality in different regions.
2Ease of operation
If the inner diameter of the core is increased to reduce fitting pressure, then the bead portion is less likely to be caught by the hump, but the bead unseating resistance is reduced
Solution Approach 1:
The heel face is divided into multiple regions by vent lines extending in the circumferential direction. This segmentation allows the heel face to have a larger arc radius (8-15mm) that reduces fitting pressure without requiring an increased core diameter, thereby maintaining bead unseating resistance while achieving lower fitting pressure.
3Ease of operation
If the number of wire windings is reduced to reduce fitting pressure, then the bead portion is less likely to be caught by the hump, but the bead unseating resistance is reduced
Solution Approach 1:
The heel face contour is segmented by vent lines that extend in the circumferential direction. This allows the heel face to have a larger arc radius (8-15mm) that reduces fitting pressure without reducing the number of wire windings, thereby maintaining bead unseating resistance while achieving lower fitting pressure.
Data Source
AI summary
A tire 22 includes a pair of bead portions 66 to be fitted to a rim R. Each bead portion 66 includes a bead 30 having a core 52 and an apex 54. An outer surface 68 of the bead portion 66 includes a seat face 70 and a flange face 72 disposed radially inward and axially outward, respectively, of the bead 30, a heel face74 disposed between the seat face 70 and the flange face 72, and a plurality of vent lines 78 projecting from the heel face 74 and extending in the circumferential direction. A contour of the heel face 74 is represented by an arc on a cross-section, of the tire 22, taken along a plane including a rotation axis of the tire 22, and a radius Rh of the arc is not less than 8 mm and not greater than 15 mm.