Pneumatic Tyre Crown Reinforcement Mass Reduction
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Solution Overview
Problem
Heavy-duty tires face challenges in maintaining endurance and resistance to road hazards while reducing mass and manufacturing costs, as existing solutions either increase tire mass or fail to improve endurance performance when lightened.
Innovation Solution
A tire design with a radial carcass reinforcement featuring at least two working crown layers of metal cables with specific distribution pitches and elastomeric mixture thicknesses, along with a protective layer, which reduces metal usage while maintaining endurance through optimized stress distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the number of layers or density of crown reinforcement is increased to improve endurance and resistance to road hazards, then the tire mass increases
Solution Approach 1:
The patent changes the material parameters of the crown reinforcement by using high-strength steel cables with specific tensile strength ranges (1700-2500 MPa) and optimizing the elastomeric mixture composition with specific rubber compounds and additives. This allows achieving the required endurance and road hazard resistance with reduced reinforcement density, thereby lowering tire mass while maintaining reliability
Solution Approach 2:
The patent employs composite material structures by combining steel cables with specially formulated elastomeric mixtures containing rubber compounds, fillers, and additives. This composite approach creates a synergistic effect where the steel provides tensile strength and the elastomeric mixture provides flexibility and shock absorption, enabling reduced material quantity while maintaining or improving endurance and road hazard resistance
2Weight of moving object
If the amount of metal in crown reinforcement is reduced to decrease tire mass and manufacturing costs, then the endurance performance deteriorates
Solution Approach 1:
The patent optimizes critical parameters including steel cable tensile strength (1700-2500 MPa), cable diameter (0.6-1.3 mm), spacing between cables (5-20 mm), and elastomeric mixture composition. These parameter optimizations ensure that reduced metal quantity does not compromise endurance, as the high-strength cables and optimized elastomeric matrix maintain structural integrity under repeated stress
Solution Approach 2:
The patent applies local quality by varying the reinforcement density and cable specifications in different regions of the crown. The spacing between cables (5-20 mm) and cable dimensions are optimized locally based on stress distribution patterns, providing enhanced durability in high-stress areas while reducing material in lower-stress zones, thus maintaining endurance with reduced overall metal content
3Weight of moving object
If high-strength steel cables with specific tensile strength ranges are used to maintain endurance with reduced mass, then the manufacturing precision requirements increase
Solution Approach 1:
The patent specifies optimized parameter ranges that balance performance and manufacturability: cable spacing of 5-20 mm, cable diameters of 0.6-1.3 mm, and elastomeric mixture thicknesses of 1-5 mm. These parameter ranges are wide enough to accommodate normal manufacturing variations while still achieving the desired mass reduction and endurance performance, thereby reducing the stringency of precision requirements
Solution Approach 2:
The patent promotes homogeneity in the elastomeric mixture composition and cable distribution patterns to reduce manufacturing variability. By using consistent material formulations and regular spacing intervals, the patent minimizes the impact of manufacturing tolerances on final product performance, making the manufacturing process more robust and less sensitive to precision variations
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 design achieves reduced tire mass while maintaining equivalent endurance and resistance to road hazards, as demonstrated by tests showing comparable performance to reference tires in terms of distance covered and energy at rupture during impacts.
Implementation Method 1
said reinforcing elements of the radially outermost working top layer being radially separated from the reinforcing elements of the protective layer radially closest to the radially outermost working top layer by elastomeric mixtures
Data Source
Figure 1
Figure 2
AI summary
The invention relates to a tyre comprising a crown reinforcement (4) formed of at least two working crown layers (42, 43) of reinforcing elements, the reinforcing elements of the radially outermost working crown layer (43) being distributed at a spacing P, and of at least one protective layer (44). According to the invention, the reinforcing elements of the working crown layers are metal cords of a diameter of less than 1.3 mm, at least one thread of each metal cord of at least one working crown layer is of at least UHT grade, the ratio Ei/P is strictly greater than 0.23 and the ratio E2/P is strictly greater than 0.30.