Radial Tire Crown Sublayer Using Thermoplastic Elastomer
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Solution Overview
Problem
Tires face a challenge in balancing high resistance to wear and low rolling resistance while maintaining good road behavior, as increasing the stiffness of the crown to improve handling can penalize hysteresis properties and rolling resistance.
Innovation Solution
A radial tire design featuring a crown reinforcement with a radially internal elastomeric underlayer comprising a rubber composition of diene elastomers and thermoplastic styrenic copolymers, which enhances stiffness and road behavior while maintaining or reducing hysteresis and rolling resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If the stiffness of the crown is increased to improve handling, then road behavior is improved, but hysteresis properties are penalized and rolling resistance increases
Solution Approach 1:
The patent applies local quality by creating an underlayer with specific local properties (comprising thermoplastic elastomer and diene elastomer in specific ratios) positioned between the belt and outer tread layer. This localized structural modification allows the crown to achieve improved stiffness and handling without uniformly increasing hysteresis across the entire tire structure, thereby resolving the contradiction between crown stiffness and rolling resistance.
2Stability of the object's composition
If the stiffness of the crown is increased to improve handling, then road behavior is improved, but wear resistance may be compromised
Solution Approach 1:
The patent employs composite materials by formulating the underlayer with a specific combination of thermoplastic elastomer (2-20 phr) and diene elastomer (10-60 phr) along with reinforcing fillers. This composite formulation enables the crown to simultaneously achieve enhanced stiffness for improved handling and adequate wear resistance, resolving the contradiction between these two performance requirements.
Data Source
Figure 1
AI summary
The invention relates to a radial-ply tire (1) for a motor vehicle which comprises: a tread (3) mounted on a crown (2), wherein said tread is provided with at least one radially external elastomer layer (3a) designed to come into contact with the road when the tire is rolling; two inextensible beads (4), two sidewalls (5) connecting the beads (4) to the tread (3), a carcass reinforcement (6) running within the two sidewalls (5) and anchored to the beads (4); the crown (2) being reinforced with a crown reinforcement or belt (7) arranged circumferentially between the carcass reinforcement (6) and the tread (3); a radially internal elastomer layer (3b) referred to as a sublayer having a formulation different from that of the radially external elastomer layer (3a), said sublayer being arranged between the radially external layer (3a) and the belt (7), characterized in that said sublayer comprises a rubber composition comprising at least one diene elastomer, a reinforcing filler and a thermoplastic styrene copolymer (called a "TPS elastomer"). The use of the TPS copolymer allows an increase in stiffness of the sublayer and hence an improvement in the road handling of the tires, while retaining a good level of hysteresis and therefore of rolling resistance.