Tire Crown Reinforcement with Rubber Compound Layer

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Solution Overview

Problem

Current heavy-duty tires face endurance issues due to shear stresses and increased operating temperatures, leading to cracks and reduced cornering stiffness, especially under high-speed and overload conditions, which affect their rolling resistance and fuel efficiency.

Innovation Solution

A tire design with a radial carcass reinforcement featuring a crown reinforcement structure that includes a layer of rubber compound with specific elastic modulus and loss factor values, combined with circumferential reinforcing elements, to decouple working crown layers and reduce shear stresses, while maintaining endurance and improving cornering stiffness.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a layer of rubber compound is placed between the ends of working crown layers to decouple them, then shear stresses are reduced and endurance is improved, but the cornering stiffness deteriorates

Engineering Contradiction:

ImproveenduranceVSAvoidcornering stiffness

Core Design Contradiction:

ReliabilityVSStrength

Solution Approach 1:

The patent applies parameter changes by precisely controlling the elastic modulus (greater than 9 MPa) and loss factor (tan δ max less than 0.100) of the rubber compound layer. These specific parameter ranges optimize the balance between decoupling effectiveness for endurance and maintaining sufficient stiffness for cornering performance.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent uses composite materials by combining the rubber compound layer with circumferential reinforcing elements (metallic threads or cords at angles of 45° to 90°). This composite structure provides both the decoupling function for endurance and the reinforcing function for cornering stiffness.

Inventive Principle:

Principle #40Composite materials

2Loss of energy

If circumferential reinforcing elements are added to improve rolling resistance, then fuel efficiency is improved, but the device complexity increases

Engineering Contradiction:

Improverolling resistanceVSAvoidstructure complexity

Core Design Contradiction:

Loss of energyVSDevice complexity

Solution Approach 1:

The circumferential reinforcing elements serve multiple functions: they reduce rolling resistance by limiting radial expansions, provides structural reinforcement, and work synergistically with the rubber compound layer to maintain cornering stiffness. This multi-functionality justifies the added structural complexity.

Inventive Principle:

Principle #6Universality (Multi-functionality)

3Duration of action of moving object

If the tire is designed for high-speed and long-distance running, then wear is reduced, but the endurance of crown reinforcement deteriorates due to increased temperature and shear stresses

Engineering Contradiction:

Improvedistance travelledVSAvoidendurance of crown reinforcement

Core Design Contradiction:

Duration of action of moving objectVSReliability

Solution Approach 1:

The rubber compound layer acts as an intermediary element between the working crown layers. It absorbs and distributes shear stresses, particularly at the ends of the axially shortest crown layer, preventing stress concentration and crack initiation that would otherwise occur during high-speed, long-distance operation.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent specifies precise parameter ranges for the rubber compound layer (elastic modulus greater than 9 MPa, loss factor tan δ max less than 0.100) to optimize its ability to withstand temperature increases and shear stresses during extended high-speed operation, thereby maintaining crown reinforcement endurance.

Inventive Principle:

Principle #35Parameter changes

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 design enhances endurance and rolling resistance performance, maintaining cornering stiffness even under high wear and overload conditions, thereby contributing to reduced fuel consumption and improved dynamic properties.

Implementation Method 1

a layer C of rubber compound placed between at least the ends of the said at least two working crown layers... to decouple working crown layers and reduce shear stresses

Methodology Applied

Scientific EffectShear stress reduction: Shear Stress

Implementation Method 2

The circumferential reinforcing elements limit the radial expansions of the crown reinforcement

Methodology Applied

Scientific EffectRadial expansion constraint:

Implementation Method 3

a first layer S of polymer compound in contact with at least one working crown layer and in contact with the carcass reinforcement

Methodology Applied

Scientific EffectStructural support:

Data Source

PatentUS10286730B2Tire comprising a layer of circumferential reinforcement elements

Publication Date: 2019.05.14 MICHELIN & CO (CIE GEN DES ESTAB MICHELIN)

AI summary

A tire comprising a crown reinforcement formed of at least two working crown layers each one formed of reinforcing elements inserted between two skim layers of rubber compound, a first layer S of polymer compound being in contact with at least one working crown layer and in contact with the carcass reinforcement and the crown reinforcement comprising at least one layer of circumferential reinforcing elements. The elastic modulus under tension at 10% elongation of the layer C is greater than 9 MPa, the maximum value of tan(δ), denoted tan(δ)max, of the layer C is less than 0.100 and the complex dynamic shear modulus G*, measured at 10% and 60° C. on the return cycle, of the first layer S of polymer compound is greater than 1.35 MPa.