Tire Groove Bottom Protective Layer for Tear Resistance

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Solution Overview

Problem

Heavy-load vehicle tires suffer from premature decay due to stress concentration and fatigue at the edges of the tread grooves, leading to anomalies, cracks, and reduced lifespan, as existing solutions with lining layers face premature ageing and loss of elasticity.

Innovation Solution

A tire design featuring a tread band with a protective layer of higher tear strength than the tread material applied to the groove bottom, with a tear strength ratio of at least 1.5, to enhance resistance to tearing and extend tire life.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a lining layer with low modulus is superposed on the groove bottom to protect against anomalies, then resistance to groove anomalies is improved, but the lining layer undergoes severe strain cycles leading to premature ageing and loss of elasticity

Engineering Contradiction:
Improveresistance to groove anomaliesVSAvoidservice life of lining layer
Core Design Contradiction:
ReliabilityVSDuration of action of moving object

Solution Approach 1:

The patent changes the key parameter from modulus (elasticity) to tear strength. The protective layer has high tear strength (at least 1.5 times the tread band material) but maintains modulus comparable to the tread band material, avoiding the strain incompatibility issue. This parameter substitution resolves the contradiction by focusing on the critical property (tear resistance) rather than elasticity.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent uses composite material construction with a protective layer made from elastomeric material having different properties than the tread band. The protective layer combines high tear strength with compatible modulus, creating a composite structure that protects against anomalies while enduring strain cycles without premature ageing.

Inventive Principle:
Principle #40Composite materials

2Strength

If the protective layer has high elongation-at-break to resist tearing, then tear resistance is improved, but the difference in modulus between lining layer and tread band increases causing severe strain cycles

Engineering Contradiction:
Improvetear strengthVSAvoidmodulus compatibility
Core Design Contradiction:
StrengthVSStability of the object's composition

Solution Approach 1:

The patent identifies tear strength as the critical parameter for anomaly resistance, not elongation-at-break. By substituting the focus from elasticity metrics to strength metrics, the patent enables use of materials with high tear strength and compatible modulus, resolving the contradiction between tear resistance and modulus compatibility.

Inventive Principle:
Principle #35Parameter changes

Data Source

PatentEP2379349B1Tire for vehicle wheels provided with tread band protected against groove anomalies
Publication Date: 2013.06.12 PIRELLI TYRE SPA
  • EP2379349B1 patent drawingFigure 1
  • EP2379349B1 patent drawingFigure 2

AI summary

A tire for vehicle wheels comprises a tread band including a first elastomeric material with a first tear strength and comprising a plurality of circumferential grooves formed in said tread, each of said circumferential grooves being defined by a couple of lateral walls separated by a bottom, at least one of said grooves including a protective layer of a second elastomeric material with a second tear strength superimposed on at least said groove bottom, wherein the ratio between the values of said second tear strength and said first tear strength is at least 1.5