Hybrid Carcass Yards for High-Speed Tyre Stability
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Solution Overview
Problem
High-performance tires face challenges in maintaining roadholding and stability under high-speed and thermomechanical stress conditions due to deformation and heat-induced modulus reduction in carcass materials like rayon, which are hygroscopic and sensitive to temperature changes.
Innovation Solution
The use of hybrid yarns comprising a mixture of polyester and low-temperature decay fibers such as aramide or carbon, where the polyester fibers make up at least 50% of the hybrid yarn, to create a carcass structure that maintains modulus stability and reduces deformation under varying temperatures and humidity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If rayon cords are used in the carcass ply to achieve good fatigue strength and elasticity, then the tyre shows improved dynamic behavior and roadholding, but the modulus of elasticity reduces significantly when temperature increases due to thermoplastic behavior
Solution Approach 1:
The patent applies composite materials by combining aramidic fibers (which maintain high modulus at elevated temperatures) with polyester or nylon fibers (which provide good elasticity and fatigue resistance). This hybrid cord structure creates a synergistic effect where the aramidic component compensates for the thermoplastic behavior of polyester/nylon at high temperatures, while the polyester/nylon component provides the elasticity needed for dynamic tire performance. The composite cord thus resolves the contradiction between maintaining roadholding reliability and preserving modulus stability at high operating temperatures.
2Reliability
If rayon is used as the reinforcing material in the carcass, then the tyre achieves optimal balance between performance and fatigue strength, but the material shows hygroscopic behavior leading to modulus reduction and production defects
Solution Approach 1:
The patent replaces the hygroscopic rayon material with a hybrid cord system based on polyester and aramidic fibers. Polyester fibers are inherently more resistant to moisture absorption compared to rayon, and when combined with aramidic fibers, the hybrid cord achieves comparable or superior fatigue strength without the hygroscopic problems. This substitution eliminates production defects related to moisture content variability while maintaining the optimal balance between performance and durability.
3Speed
If high-performance tyres are designed for speeds above 200 km/h, then the tyre must withstand high centrifugal forces, but this generates deformations that reduce the footprint area and adversely modify performance
Solution Approach 1:
The patent employs hybrid cords made of aramidic and polyester/nylon fibers in the carcass ply to resist high centrifugal forces generated at speeds above 200 km/h. The aramidic fibers provide exceptional tensile strength and dimensional stability under high-speed rotation, while the polyester or nylon fibers contribute elasticity and energy absorption. This composite structure maintains the tyre's circular shape and footprint area better than conventional single-material cords, thereby preserving contact patch integrity and performance at high operating speeds.
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
This approach enhances the dynamic behavior and stability of high-speed tires by maintaining a stable modulus and reducing the risk of defects associated with hygroscopic materials, while also lowering production costs and improving performance uniformity.
Implementation Method 1
hybrid yarns comprising a mixture of polyester and low-temperature decay fibers such as aramide or carbon, where the polyester fibers make up at least 50% of the hybrid yarn, to create a carcass structure that maintains modulus stability and reduces deformation under varying temperatures and humidity
Implementation Method 2
high running speeds of the vehicle, higher than 200 km/h, generate centrifugal forces capable of radially deforming the tyre, radially modifying the outwards outline thereof
Implementation Method 3
the carcass determines the load capability that can be borne by the tyre, the comfort offered by the tyre and the dynamic behaviour of same. Therefore, for the carcass material well balanced proportions of strength and elasticity under all conditions are required
Data Source
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AI summary
The present invention relates to a method of increasing the high-speed performance of a carcass structure in a tyre for vehicle wheels. The method includes: preparing at least one hybrid yarn (13) and assembling a carcass structure (2) comprising at least one carcass ply (3a, 3b) substantially built on cords (12) comprising the hybrid yarn (13). The hybrid yarn (13) comprises a plurality of filaments (14a, 15a) obtained from a first multi-filament yarn (14) of polyester and a second multi-filament yarn (15) having a decay of the modulus with the temperature lower than 20%. Each of the first multi-filament yarn (14) and second multi-filament yarn (15) comprises a plurality of individual filaments (14a, 15a). The individual filaments (14a) of the first multi-filament yarn (14) are at least partly mixed in proportions of at least 50% with the individual filaments (15a) of said second multi-filament yarn (15).