Drop-Shaped Tire Bead Core for Stability and Air Sealing

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Solution Overview

Problem

Existing pneumatic tires face challenges in maintaining bead stability and air sealing performance without compromising other tire properties.

Innovation Solution

The pneumatic tire incorporates a drop-shaped bead core with a circular portion and a tapering portion, along with an apex attached to the bead core, which enhances stability and air sealing while maintaining tire performance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a conventional bead structure is used, then the tire can be manufactured with simple structure, but the bead stability and air sealing performance are insufficient

Engineering Contradiction:
Improvebead stability and air sealing performanceVSAvoidbead structure complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The bead core is divided into two distinct portions: a circular portion providing structural foundation and a tapering portion extending radially outwardly to engage with the apex. This segmentation allows each portion to fulfill specific functions - the circular portion maintains overall bead integrity while the tapering portion enhances air sealing and stability through apex engagement.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The bead core transitions from a symmetric circular cross-section to an asymmetric tapering cross-section that radially outwardly extends. This asymmetric geometry creates a wedge-shaped interface with the apex, improving mechanical interlocking and air sealing performance while maintaining manufacturing feasibility.

Inventive Principle:
Principle #4Asymmetry

2Strength

If the bead core cross sectional area is increased to improve stiffness, then mounting surface support is improved, but the tire width and overall dimensions increase

Engineering Contradiction:
Improvebead stiffness and mounting surface supportVSAvoidtire width and overall dimensions
Core Design Contradiction:
StrengthVSArea of moving object

Solution Approach 1:

The bead core concentrates its cross-sectional area in specific critical regions - the circular portion provides foundational support while the tapering portion radially outwardly extends to engage the apex. This localized concentration of material enhances bead stiffness and mounting surface support precisely where needed, without proportionally increasing overall tire width or unnecessary dimensions.

Inventive Principle:
Principle #3Local quality

Data Source

PatentEP4163096B1A tire comprising a drop shaped bead core and method for the manufacture
Publication Date: 2025.04.23 NOKIAN TYRES
  • EP4163096B1 patent drawingFigure 1~2
  • EP4163096B1 patent drawingFigure 3a~3c
  • EP4163096B1 patent drawingFigure 3e~3h

AI summary

The invention relates to a method for manufacturing a pneumatic tire comprising a tread, sidewalls and a first bead (151) and a second bead (152), which beads (151, 152) are spaced apart, the first bead and the second bead comprising: a drop shaped bead core (10), the drop shaped bead core (10) having a cross sectional area comprising or consisting of a circular portion (10a) and a tapering portion (10b), and an apex (20) positioned adjacent and/or against the bead core, the method comprising: connecting the apex to the drop shaped bead core, thereby obtaining an assembly comprising the drop shaped bead core and the apex, pre-forming a tire comprising said assembly, and vulcanizing the pre-formed tire, thereby obtaining the pneumatic tire. The invention further relates to a pneumatic tire.