Tire Polymeric Buffer Zone Oxygen Trapping
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Solution Overview
Problem
Current tires for heavy-duty vehicles and road buses face issues with crown reinforcement endurance due to shear stresses and temperature-related degradation, leading to cracks, and are vulnerable to punctures that can cause slow air loss and premature aging, especially when equipped with automatic inflation systems.
Innovation Solution
A tire design featuring a polymeric buffer zone between the carcass reinforcement and the radially innermost crown reinforcement layer, with a thickness that traps oxygen and includes a metal salt to catalyze oxidation, limiting crack propagation and extending retreading possibilities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the crown reinforcement uses multiple layers of reinforcing elements to improve strength, then the tire can support heavy loads, but shear stresses between layers and temperature rise cause cracks to propagate, reducing reliability
Solution Approach 1:
A buffer layer comprising a polymeric mixture is introduced between the carcass reinforcement and the radially innermost layer of reinforcing elements of the crown reinforcement. This intermediary layer traps oxygen and limits its diffusion toward the crown reinforcement, thereby preventing oxidation-induced crack propagation while maintaining the strength of the multi-layer crown reinforcement structure.
Solution Approach 2:
The buffer layer is formed from a composite polymeric mixture containing elastomers, fillers, and metal salts (such as cobalt or manganese salts) that catalyze oxidation. This composite material is designed to trap oxygen and promote controlled oxidation within the buffer zone, protecting the crown reinforcement from oxidative degradation.
2Ease of operation
If automatic inflation systems are used to maintain pressure, then tire performance is improved, but punctures allow slow air loss and oxygen diffusion, causing premature aging
Solution Approach 1:
The buffer layer acts as an oxygen-trapping intermediary between the tire cavity and the crown reinforcement. Even when punctures occur and oxygen enters the tire cavity, the buffer layer prevents this oxygen from reaching and oxidizing the crown reinforcement, thereby eliminating the premature aging problem associated with automatic inflation systems.
Solution Approach 2:
The buffer layer creates an oxygen-trapping environment that protects the crown reinforcement from oxidative exposure. By incorporating metal salts that catalyze oxidation, the buffer layer effectively sequesters oxygen in a controlled manner, creating a protective zone that shields the reinforcement from harmful oxidation.
3Reliability
If the buffer zone thickness is increased to improve oxygen trapping, then crack propagation is limited, but the device complexity and manufacturing cost increase
Solution Approach 1:
The buffer layer thickness is optimized within a specific range (greater than φ but less than 3φ, where φ is the diameter of the reinforcing elements). This parameter optimization ensures sufficient oxygen-trapping capacity and crack propagation limitation while avoiding excessive thickness that would increase complexity and manufacturing cost. The metal salt concentration is also optimized at 0.2-0.3 parts by weight per 100 parts of elastomer.
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 polymeric buffer zone effectively limits crack propagation and allows tires to travel significantly more kilometers before unacceptable damage occurs, enabling retreading and reducing the initial cost with significant gains in retreading expectancy.
Implementation Method 1
a first layer of polymeric compound radially between the carcass reinforcement and the radially innermost layer of reinforcing elements of the crown reinforcement, said first layer of polymer mixture constituting a buffer zone provided to trap oxygen outside said first layer
Implementation Method 2
including a metal salt to catalyze oxidation
Implementation Method 3
a first layer of polymeric compound radially between the carcass reinforcement and the radially innermost layer of reinforcing elements of the crown reinforcement, said first layer of polymer mixture constituting a buffer zone provided to trap oxygen outside said first layer
Data Source
Figure 1
Figure 2
AI summary
The invention relates to a tire having a radial carcass reinforcement (2) consisting of at least one layer of metal reinforcing elements, said tire including a crown reinforcement (5) which is in turn capped with a tread, said tread being joined to two beads via two sidewalls, said tire further including a first layer of a polymer mixture (7) that is radially arranged between the carcass reinforcement and the layer of reinforcing elements (51) which is the radially innermost layer of the crown reinforcement. According to the invention, said one first layer of a polymer mixture constitutes a buffer area that is provided to trap the oxygen outside of said first layer, the axial width of said first layer being at least equal to 70% of the width of the layer of reinforcing elements which is the radially innermost layer of the crown reinforcement.