Polyamide Monofilament Cord for High-Speed Tire Overlay
Solution Overview
Problem
Current tire reinforcement materials in the Ultra Ultra High Performance (UUHP) segment, particularly in overlay plies, face limitations in achieving high speed performance, durability, cornering force, and ride handling, with existing solutions like hybrid cords and monofilament-based constructions not fully addressing the need for improved stiffness and fatigue resistance.
Innovation Solution
A tire ply strip reinforced with a cord comprising 6 to 10 polyamide monofilament plies twisted together at specific densities and twist levels, optimized for high bending stiffness and flex-fatigue resistance, coated with an adhesive for enhanced adhesion to the rubber matrix, and designed for race and passenger car applications.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If higher twist levels are used in cords, then cord strength and stiffness are improved, but internal torques increase causing non-uniform cord distribution and crack initiation
Solution Approach 1:
The patent optimizes the twist level parameter to a specific range (1.5 to 2.5 twists per 2.54 cm) to balance cord strength and uniformity. This parameter optimization ensures sufficient bending stiffness while preventing excessive internal torques that would cause non-uniform cord distribution and crack initiation, thereby resolving the contradiction between strength and reliability.
2Reliability
If lower twist levels are used in cords, then internal torques are reduced, but cord-ply separation occurs under compression leading to cord breaking
Solution Approach 1:
The patent establishes a minimum twist level threshold (1.5 to 2.5 twists per 2.54 cm) to prevent cord-ply separation under compression. This optimized parameter ensures sufficient friction and interlocking between cord and ply, maintaining ply strength and preventing cord breaking while avoiding excessive twist that would cause uniformity issues.
3Speed
If hybrid cords consisting of aramid yarn and Nylon yarn are used, then high speed performance is improved, but device complexity increases
Solution Approach 1:
The patent employs composite cord construction combining aramid yarn and Nylon yarn in a twisted cord structure. This composite approach leverages the high strength and heat resistance of aramid combined with the flexibility and adhesion properties of Nylon, achieving superior high-speed performance while maintaining manageable construction complexity through established twisting processes.
Data Source
Figure 1~3
AI summary
The invention relates to a passenger car tire comprising a carcass having at least one carcass ply, a tread disposed radially outward of a crown region of the carcass, a belt with a plurality of belt plies arranged between the carcass and the tread, and an overlay structure covering the belt and comprising a helically wound overlay ply strip reinforced by at least one textile cord. The cord comprises from 6 to 10 polyamide monofilament plies having each a density from 300 to 470 dtex, wherein the monofilament plies are twisted together by between 1 and 2 twists per inch to form the cord. The invention relates also to a corresponding cord.