Multi-Strand Tire Cord Structure for Elastomer Penetration

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Solution Overview

Problem

Heavy industrial vehicle tires are prone to perforations on uneven surfaces, allowing corrosive agents to enter and oxidize the metal reinforcing elements, significantly reducing their lifespan, and increasing the cord diameter or number of cords to enhance breaking force compromises flexibility and penetrability.

Innovation Solution

A two-layer multi-strand cable with a desaturated outer layer, characterized by a specific pitch ratio and inter-strand distance, allowing elastomer composition to penetrate and form a protective matrix, reducing corrosion while maintaining mechanical integrity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If the cord diameter is increased to enhance breaking force, then the breaking force is improved, but the flexibility of the cord decreases

Engineering Contradiction:
Improvebreaking forceVSAvoidflexibility
Core Design Contradiction:
StrengthVSEase of operation

Solution Approach 1:

The cord is segmented into multiple strands (e.g., 7 strands) instead of using a single thick cord. Each strand contains multiple wires (e.g., 19 wires per strand), creating a hierarchical segmented structure that maintains flexibility while achieving high breaking force through the combined strength of numerous smaller elements.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The cord uses a composite structure combining metal wires with elastomeric composition. The metal wires provide tensile strength while the elastomeric material provides flexibility and corrosion protection, creating a composite that achieves both high breaking force and maintained flexibility.

Inventive Principle:
Principle #40Composite materials

2Strength

If the number of cords is increased to enhance breaking force, then the breaking force is improved, but the penetrability of the strands by elastomer composition decreases

Engineering Contradiction:
Improvebreaking forceVSAvoidpenetrability
Core Design Contradiction:
StrengthVSEase of manufacture

Solution Approach 1:

The cord structure is segmented into strands with controlled wire arrangements that create inter-wire spaces. This segmentation allows elastomer composition to penetrate between wires during manufacturing while still achieving high breaking force through the combined strength of multiple cords and wires.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The strand structure incorporates controlled porosity through the arrangement of wires with different diameters and winding patterns, creating channels and spaces that allow elastomer composition to penetrate and impregnate the strand structure during manufacturing, while maintaining structural integrity for high breaking force.

Inventive Principle:
Principle #31Porous materials

3Strength

If the unit strength of each cord is increased to enhance breaking force, then the breaking force is improved, but significant investment in cord manufacturing facilities is required

Engineering Contradiction:
Improvebreaking forceVSAvoidmanufacturing facility investment
Core Design Contradiction:
StrengthVSDevice complexity

Solution Approach 1:

Instead of manufacturing fewer high-strength cords requiring advanced facilities, the solution segments the structure into many standard-strength wires and strands that can be manufactured using conventional equipment. The cumulative strength of numerous standard components achieves the required breaking force without requiring significant investment in specialized manufacturing facilities.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The invention changes the parameters from few high-strength cords to many standard-strength wires, adjusting the quantity and arrangement parameters rather than increasing individual wire strength parameters. This approach achieves the same breaking force using standard manufacturing capabilities.

Inventive Principle:
Principle #35Parameter changes

4Strength

If a saturated outer layer is used in the cable, then the breaking force is maximized, but the penetrability by elastomer composition decreases

Engineering Contradiction:
Improvebreaking forceVSAvoidpenetrability
Core Design Contradiction:
StrengthVSEase of manufacture

Solution Approach 1:

The cable employs local quality variation where the outer layer has a specific loose arrangement with controlled inter-strand distances (e.g., at least 30 μm) that differs from the inner layers. This local structural characteristic in the outer layer enables elastomer penetration while the overall cable structure maintains high breaking force through the combined strength of all layers.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The cable uses a composite structure where the outer layer serves dual functions: providing mechanical strength as part of the overall cable strength while simultaneously serving as a penetrable barrier that allows elastomer composition to reach inner strands, achieving both strength and corrosion protection functions.

Inventive Principle:
Principle #40Composite materials

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 cable design enhances penetrability and accessibility of the internal strands by the elastomer composition, limiting corrosive agent entry and propagation, while maintaining breaking force and flexibility.

Implementation Method 1

the elastomeric composition penetrates the capillaries present between each layer of each strand

Methodology Applied
Scientific EffectCapillary action: Capillary Action

Data Source

PatentEP3810849B1Double-layer multi-strand cord with improved penetrability
Publication Date: 2025.08.06 MICHELIN & CO (CIE GEN DES ESTAB MICHELIN)
  • EP3810849B1 patent drawingFigure 1~2
  • EP3810849B1 patent drawingFigure 3
  • EP3810849B1 patent drawingFigure 4

AI summary

The disclosed cord (50) comprises: - K > 1 inner strands (TI) comprising an inner layer (C1) and an outer layer (C3); - L > 1 outer strands (TE) comprising an inner layer (C1') consisting of Q'=1 inner wire (F1'), an intermediate layer (C2') consisting of M' intermediate wires (F2') wound around the inner layer (C1') at a pitch p2', and an outer layer (C3') consisting of N' outer wires (F3') wound around the intermediate layer (C2') at a pitch p3'; the average inter-strand distance E separating two adjacent outer strands is at least 30 μm; the intermediate layer (C2') of each outer strand (TE) is desaturated; the outer layer (C3') of each outer strand (TE) is desaturated; and 0.36 ≤ (p3'-p2')/p3' ≤ 0.57.