Tyre Carcass Reinforcement Cords with Low Permeability
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Solution Overview
Problem
Heavy-duty tires for worksite applications face significant wear and endurance issues due to severe rolling conditions, leading to 'fatigue-fretting' and 'fatigue-corrosion' of carcass reinforcement cords, which reduces their lifespan and is exacerbated by under-inflation, causing buckling and increased stress.
Innovation Solution
A tire design with a radial carcass reinforcement featuring hooped cables that exhibit low air permeability and a thicker rubber compound layer between the inner surface and the metal reinforcement elements, combined with a crosslinkable rubber sheath, to enhance corrosion resistance and mechanical anchoring, thereby reducing buckling risks and maintaining performance across varying conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the thickness of the rubber layer is increased to reduce permeability and protect cords, then corrosion resistance improves, but manufacturing cost increases
Solution Approach 1:
The patent optimizes the thickness parameter of the rubber layer to a specific range (4-7mm) that provides sufficient corrosion protection while controlling manufacturing costs. This parameter optimization resolves the contradiction by finding the optimal balance point between protection and cost.
Solution Approach 2:
The patent uses composite rubber compositions with specific properties (permeability less than 20 cm³/min in the permeability test) to achieve effective corrosion protection at reduced thickness, thereby lowering manufacturing costs while maintaining reliability.
2Duration of action of moving object
If cord diameter is reduced to improve flexibility and bending endurance, then flexibility improves, but resistance to fatigue-fretting-corrosion worsens
Solution Approach 1:
The patent specifies optimal cord diameter ranges that balance flexibility and corrosion resistance, preventing both excessive wear from bending and vulnerability to fatigue-fretting-corrosion.
Solution Approach 2:
The patent employs composite cable structures combining different materials and configurations to achieve both high flexibility for bending endurance and sufficient mass/structure to resist fatigue-fretting-corrosion.
3Reliability
If hooped cables with low permeability are used to reduce corrosion, then corrosion resistance improves, but risk of buckling under under-inflation increases
Solution Approach 1:
The patent uses composite hooped cable structures that combine low-permeability materials for corrosion protection with sufficient structural strength and hoop strength to resist buckling under under-inflation conditions.
Solution Approach 2:
The patent optimizes parameters of the hooped cables including hoop strength, cable tension, and structural configuration to simultaneously achieve low permeability for corrosion resistance and sufficient buckling resistance.
4Reliability
If a thicker rubber compound layer is used to protect reinforcement elements, then protection against corrosion improves, but manufacturing cost increases
Solution Approach 1:
The patent optimizes the rubber compound layer thickness to the optimal range of 4-7mm, providing sufficient corrosion protection while controlling the additional material cost and manufacturing complexity.
Solution Approach 2:
The patent uses composite rubber compounds with enhanced protective properties that provide effective corrosion resistance at optimized thicknesses, reducing the need for excessive material usage.
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 the endurance and wear resistance of the tires while reducing manufacturing costs by limiting corrosion and buckling, maintaining performance under normal and under-inflated conditions, and preventing unwinding of the carcass reinforcement.
Implementation Method 1
a sheath consisting of a crosslinkable or crosslinked rubber composition
Implementation Method 2
exhibiting in the so-called permeability test a flow rate of less than 20 cm³/min
Data Source
Figure 1a
Figure 1b
Figure 2~4
AI summary
The invention relates to a tyre with a radial carcass reinforcement (2), said tyre comprising a crown reinforcement in turn capped radially by a tread. According to the invention, the metal reinforcement elements (11) of the carcass reinforcement are non-hooped cords which, during so-called permeability testing, have a flow rate of less than 20 cm3/mn over all of the axial profile of the tyre, the rubber mixture thickness E between the internal surface (10) of the tyre cavity (8) and the point (12) of a metal reinforcement element of the carcass reinforcement being between 1.0 and 3.0 mm.