Tyre Bead Polymer Layering for Low Rolling Resistance
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Solution Overview
Problem
Heavy-duty tires face issues with bead area brittleness under severe conditions, reduced rolling resistance, and unsatisfactory endurance and wear performance due to weight reduction in the bead area.
Innovation Solution
A tire design with a radial carcass reinforcement featuring multiple polymer mixture layers in the bead area, including a sixth layer with specific dynamic properties to enhance rolling resistance and endurance, and a carcass reinforcement anchored by folding layers reinforced by polymeric mixtures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the bead area is reduced in weight to improve rolling resistance, then rolling resistance performance improves, but bead area durability and wear resistance deteriorate
Solution Approach 1:
The patent applies different material properties to different regions of the bead area. Specifically, it uses a first polymeric mixture with specific dynamic properties (tan δ at 60°C between 0.06-0.10) in the outer bead region that contacts the rim, while using a second polymeric mixture with different properties (tan δ at 60°C between 0.10-0.18) in the inner bead region. This local differentiation allows the outer region to optimize for rolling resistance while the inner region maintains durability and wear resistance.
Solution Approach 2:
The patent employs composite material construction by combining two distinct polymeric mixtures with different rheological and dynamic properties. The first polymeric mixture has lower tan δ values for reduced hysteresis and rolling resistance, while the second has higher tan δ values for enhanced durability. This composite approach allows simultaneous optimization of both rolling resistance performance and bead area durability that cannot be achieved with a single homogeneous material.
2Strength
If reinforcing elements are added to prevent bead brittleness, then bead area strength improves, but rolling resistance performance deteriorates
Solution Approach 1:
The patent optimizes the dynamic parameters of the polymeric mixtures, specifically controlling the tan δ values at different temperatures. By selecting mixtures with tan δ at 60°C between 0.06-0.18 and specific glass transition temperatures, the patent achieves the right balance between strength and energy loss. The first polymeric mixture with lower tan δ provides strength with minimal energy dissipation, while the second provides enhanced strength with acceptable energy loss characteristics.
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 tire design achieves improved rolling resistance, endurance, and wear performance, maintaining bead area durability and resisting impacts, while compensating for weight reduction effects.
Implementation Method 1
the maximum value of tan(δ), denoted tan(δ)max, measured at 60°C, of the sixth layer of polymer mixture(s) being less than 0.050 and the linearity ratio of the complex dynamic shear modulus G*, at a temperature of 23°C, of the sixth layer of polymer mixture(s) being greater than 0.80
Implementation Method 2
the polymer mixture(s) present in a circle centered on the end of the reversal of the carcass reinforcement and having a radius of at least 1.5 mm has a secant modulus of elasticity at 10% elongation greater than 6 MPa
Implementation Method 3
the layer of reinforcing elements of the carcass reinforcement being anchored in each of the beads by folding around a bead to form a main part of the carcass reinforcement layer extending from one bead to the other and a folding of the carcass reinforcement layer in each of the beads
Data Source
Figure 1
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AI summary
The invention relates to a tyre having a radial carcass reinforcement formed by a single layer of reinforcing elements which is anchored in each of the beads, being turned up around a bead wire, and reinforced by a stiffener. According to the invention, a sixth layer of one or more polymer blends (21) is radially inside the end (8) of the turn-up (7) of the carcass reinforcement layer and axially between the turn-up (7) of the carcass reinforcement layer and the main part of the carcass reinforcement layer (2), the maximum tan(δ) value of the sixth layer of one or more polymer blends (21), denoted tan(δ)max, measured at 60° C, being less than 0.050 and the linearity ratio of the dynamic complex shear modulus G* of the sixth layer of one or more polymer blends (21), at a temperature of 23° C, being greater than 0.80.