Pneumatic Tire Bead Insulation for Rim Fittability

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Solution Overview

Problem

Pneumatic tires face challenges in achieving both excellent fittability to a rim and airtightness, with existing solutions either improving fittability at the cost of increased time and labor or compromising airtightness.

Innovation Solution

A pneumatic tire design featuring a pair of beads with cores, a carcass extended along the tread and sidewalls, chafers contacting the rim, an inner liner disposed inward of the carcass, and insulation between the carcass and inner liner, with specific elastic moduli and thicknesses to reduce fastening force variation and enhance airtightness.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If an air seal is filled between the bead heels and the rim to improve airtightness, then airtightness is improved, but time and labor for mounting of the tire on a rim increase

Engineering Contradiction:
ImproveairtightnessVSAvoidmounting time
Core Design Contradiction:
ReliabilityVSLoss of time

Solution Approach 1:

The inner liner lower portions automatically contact the rim surface to provide airtightness without requiring manual application of air seals. The structure self-generates the sealing function through its geometric configuration and elastic deformation during mounting

Inventive Principle:
Principle #25Self-service

Solution Approach 2:

The invention extracts the airtightness function from the separate air seal component and integrates it into the inner liner structure itself, eliminating the need for additional air seal materials and their associated application steps

Inventive Principle:
Principle #2Taking out (Extraction)

2Ease of operation

If cushion layers are disposed inward of bead cores to improve fittability to a rim, then fittability is improved, but airtightness may be compromised without additional sealing measures

Engineering Contradiction:
ImprovefittabilityVSAvoidairtightness
Core Design Contradiction:
Ease of operationVSReliability

Solution Approach 1:

The invention merges the fittability function (cushioning during mounting) and airtightness function (sealing against the rim) into a single integrated structure - the inner liner lower portions that extend between the bead cores and contact the rim surface

Inventive Principle:
Principle #5Merging (Combining)

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 tire achieves improved fittability to the rim and airtightness without the need for additional air seals, reducing labor and time in mounting while maintaining durability and stability over time.

Implementation Method 1

an insulation disposed between the carcass and the inner liner in the axial direction. The insulation includes insulation lower portions disposed between the cores and the bottom surfaces of the chafers in the radial direction

Methodology Applied
Scientific EffectStress relaxation: Stress Relaxation

Implementation Method 2

The inner liner includes inner liner lower portions disposed between the cores and the bottom surfaces of the chafers in the radial direction. The inner liner lower portions extend from portions that are axially inward of the cores to portions that are axially outward thereof

Methodology Applied
Scientific EffectElasticity: Elasticity

Data Source

PatentEP3156256B1Pneumatic tire
Publication Date: 2020.05.06 SUMITOMO RUBBER INDUSTRIES LTD
  • EP3156256B1 patent drawingFigure 1
  • EP3156256B1 patent drawingFigure 2
  • EP3156256B1 patent drawingFigure 3

AI summary

A tire 2 includes: a pair of beads 10 including cores 28; chafers 22, disposed near the beads 10, which are brought into contact with a rim; an inner liner 18 disposed inward of a carcass 32 in an axial direction; and an insulation 20 disposed between the carcass 32 and the inner liner 18 in the axial direction. The chafers 22 include bottom surfaces 22a that are brought into contact with the rim in portions inward of the cores 28 in a radial direction. The insulation 20 includes insulation lower portions 20a disposed between the cores 28 and the bottom surfaces 22a of the chafers 22 in the radial direction. The inner liner 18 includes inner liner lower portions 18a disposed between the cores 28 and the bottom surfaces 22a of the chafers 22 in the radial direction.