Low Permeability Tyre Cords with Variable Rubber Thickness
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Solution Overview
Problem
Heavy-duty tires face endurance issues due to 'fatigue-fretting' and 'fatigue-corrosion' phenomena, leading to reduced lifespan and increased manufacturing costs, particularly under severe driving conditions.
Innovation Solution
A tire design with a radial carcass reinforcement featuring metal cables with low permeability and a optimized rubber compound thickness distribution, where the thickness of the rubber compound between the inner surface and the metal reinforcement elements is minimized while maintaining sufficient sealing, reducing the risk of corrosion and enhancing endurance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the thickness of the rubber compound layer is increased to improve sealing and reduce permeability, then the tire's resistance to corrosion improves, but the manufacturing cost increases
Solution Approach 1:
The patent applies local quality by varying the thickness of the rubber compound layer across different zones of the tire. The inner layer thickness is optimized locally: thicker (≥3.8mm) in zones requiring enhanced corrosion protection and thinner (<3.8mm) in zones where standard protection suffices. This localized differentiation reduces overall material usage and manufacturing cost while maintaining adequate corrosion resistance where needed.
Solution Approach 2:
The patent segments the rubber compound into multiple layers with different thicknesses and compositions. The inner layer is divided into zones with thicknesses of at least 3.8mm and zones with thicknesses less than 3.8mm. This segmentation allows selective application of thicker material only where corrosion protection is most critical, rather than uniformly increasing thickness across the entire tire structure.
2Ease of manufacture
If uniform thickness of rubber compound is used throughout the tire, then manufacturing is simpler, but corrosion protection is insufficient in critical zones
Solution Approach 1:
The patent implements local quality by specifying that the inner layer of rubber compound has a thickness of at least 3.8mm in certain zones and less than 3.8mm in other zones. This localized thickness variation provides enhanced corrosion protection in critical areas exposed to severe conditions while maintaining simpler manufacturing in less critical areas, optimizing the balance between protection and manufacturing ease.
3Reliability
If thicker rubber compound is used to prevent corrosion, then cable endurance improves, but the tire weight increases
Solution Approach 1:
The patent applies local quality by concentrating thicker rubber compound (≥3.8mm) only in specific zones where corrosion protection is most critical for cable endurance, rather than uniformly increasing thickness throughout the entire tire. This localized approach enhances cable endurance in vulnerable areas while minimizing the overall weight increase of the tire.
Solution Approach 2:
The patent segments the corrosion protection strategy by dividing the inner layer into zones with thicknesses of at least 3.8mm and zones with thicknesses less than 3.8mm. This segmentation ensures adequate cable endurance protection in critical zones while reducing unnecessary material usage and weight in areas where standard thickness suffices.
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 solution improves tire endurance and reduces manufacturing costs by limiting corrosion and maintaining performance under severe conditions, with the tire exhibiting at least 50% greater distance traveled before damage compared to reference tires, while also being lighter and 3% cheaper to produce.
Implementation Method 1
the endurance of these cords of the carcass reinforcement, it is known in particular to increase the thickness of the layer of rubber which forms the internal wall of the cavity of the tire in order to best limit the permeability of said layer
Data Source
Figure 1a
Figure 1b
Figure 1c
AI summary
Radial tyre consisting of at least one layer (2) of metal reinforcing elements (11), said tyre comprising a crown reinforcement (5) and a tread (6) which is connected to two beads (3) by two sidewalls. The metal reinforcing elements are non-wrapped cords which on what is referred to as the permeability test return a flowrate < 20 cm3/min, and the thickness of rubber compound between the interior surface (10) of the cavity (8) of the tyre and the closest point (17) of a metal reinforcing element to said interior surface is < 3.8 mm and the ratio between said thickness measured at the circumferential mid plane and said thickness in another region of the tyre is > 1.05.