Pneumatic Tire Asymmetric Contact Patch for Wear Reduction

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Solution Overview

Problem

Pneumatic tires experience uneven wear due to variations in the shape of the contact patch during different running conditions, such as straight running and cornering, leading to partial wear at specific positions of the tread portion.

Innovation Solution

A pneumatic tire design where the maximum ground contact length is positioned at an axial distance of 20% to 30% from the center towards the tread edge, with a radially outermost belt ply width of at least 0.60 times the maximum axial width, and a contour comprising arcs with specific radii of curvature, reducing the difference in contact patch shape between straight running and cornering.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If the contact patch shape varies between straight running and cornering, then the tire adapts to different running conditions, but uneven wear occurs at specific positions of the tread portion

Engineering Contradiction:
Improveadaptability to different running conditionsVSAvoiduniformity of tread wear
Core Design Contradiction:
Adaptability or versatilityVSReliability

Solution Approach 1:

The invention applies asymmetry by positioning the maximum ground contact length at an asymmetric location (20-30% from center toward first direction) rather than at the center. This asymmetric positioning compensates for the contact patch shift during cornering, making the contact patch shape more consistent between straight running and cornering conditions, thereby preventing uneven wear while maintaining adaptability

Inventive Principle:
Principle #4Asymmetry

Solution Approach 2:

The invention changes the parameter of contact patch position by specifying that the maximum ground contact length occurs at 20-30% from the center position toward the first direction. This parameter adjustment ensures that the contact patch shape remains relatively stable across different running conditions, reducing uneven wear while preserving adaptability

Inventive Principle:
Principle #35Parameter changes

2Stability of the object's composition

If the maximum ground contact length is positioned at the center, then the contact patch is symmetric during straight running, but the shape varies significantly during cornering

Engineering Contradiction:
Improvesymmetry of contact patchVSAvoidconsistency of contact patch shape
Core Design Contradiction:
Stability of the object's compositionVSAdaptability or versatility

Solution Approach 1:

The invention deliberately introduces asymmetry by positioning the maximum ground contact length at 20-30% from the center toward the first direction. This asymmetric configuration counteracts the natural shift that occurs during cornering, thereby maintaining consistency in contact patch shape across different running conditions while sacrificing perfect symmetry

Inventive Principle:
Principle #4Asymmetry

3Strength

If the radially outermost belt ply width is increased, then the structural support is improved, but the manufacturing complexity increases

Engineering Contradiction:
Improvestructural support of tread portionVSAvoidmanufacturing of belt ply
Core Design Contradiction:
StrengthVSEase of manufacture

Solution Approach 1:

The invention specifies a quantitative parameter range for the radially outermost belt ply width (0.60-0.70 times the maximum axial width of contact patch). This parameter specification provides clear manufacturing guidelines that balance structural support requirements with manufacturing feasibility, avoiding excessive complexity while ensuring adequate strength

Inventive Principle:
Principle #35Parameter changes

Data Source

PatentEP3424752B1Pneumatic tire
Publication Date: 2020.08.19 SUMITOMO RUBBER INDUSTRIES LTD
  • EP3424752B1 patent drawingFigure 1
  • EP3424752B1 patent drawingFigure 2
  • EP3424752B1 patent drawingFigure 3

AI summary

A pneumatic tire (1) has a contact patch (23) when the tire is mounted on a standard wheel rim and inflated to a standard pressure and contacted with a flat surface by loading a standard load and leaning toward a first direction (S1) in the tire axial direction at a camber angle of 3 degrees, wherein a position at which the maximum ground contact length (Lm) in the tire circumferential direction of the contact patch (23) occurs, is positioned at an axial distance (L6) of 20 % to 30 % of the maximum axial width (Wm) of the contact patch (23) from the axial center (25) of the contact patch (23) toward the first direction (S1).