Undulated Tire Working Layer for Grip and Resistance
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Solution Overview
Problem
Tires face a trade-off in achieving good grip, rolling resistance, and wear performance, with existing solutions compromising on one or more criteria, such as reducing tread pattern depth or stiffening rubber, which affects wet grip, noise, and durability.
Innovation Solution
The tire features a tread with undulated working layers made of metallic reinforcing elements coated in elastomer, forming an angle of 20° to 50° with the circumferential direction, and a crown structure with a radial stack of layers, including a carcass reinforcement and polymeric layer, maintaining the tread pattern depth while reducing the distance between the working layers and the tread surface to enhance axial stiffness and dynamic response.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the tread pattern depth is reduced, then rolling resistance is improved, but wet grip and noise performance deteriorate
Solution Approach 1:
The patent applies local quality by creating undulations in the radially outermost working layer at specific locations (shoulders and central zone) while maintaining different tread pattern depths in different zones. The undulations are positioned to be radially outer of points in line with groove centers, creating localized stiffness enhancement without uniformly reducing tread depth. This allows the tread to have deeper patterns in wet grip critical areas while maintaining shallower effective depth in rolling resistance critical areas.
Solution Approach 2:
The patent moves from a two-dimensional tread depth parameter to a three-dimensional structure by adding radial undulations to the working layer. The undulations create variations in radial position (r) as a function of axial (x) and circumferential (θ) coordinates, adding a dimensional complexity that allows independent optimization of grip and rolling resistance through spatially varying stiffness.
2Duration of action of stationary object
If rubber compound is stiffened, then wear performance is improved, but wet grip and noise performance deteriorate
Solution Approach 1:
The patent uses composite materials by combining metallic reinforcing elements coated with elastomer in the working layers. The metallic cords provide structural strength and wear resistance, while the elastomer coating provides grip properties. The crown reinforcement comprises at least one working reinforcement with metallic elements that have elastomer coating, creating a composite structure that decouples wear function from grip function.
Solution Approach 2:
The patent segments the tread structure into distinct functional layers: the tread surface with grooves for wet grip, the radially outermost working layer with undulations for structural support, and inner working layers. This segmentation allows each layer to be optimized for its specific function - the tread pattern for grip and the undulated working layer for wear resistance and stiffness.
3Strength
If the distance between working layers and tread surface is reduced, then axial stiffness and dynamic response are improved, but protection against ground attacks deteriorates
Solution Approach 1:
The patent applies dynamics by creating undulations in the radially outermost working layer that dynamically adjust the distance to the tread surface based on location. The undulations are defined by points satisfying specific radial distance conditions relative to groove centers, creating a dynamic structural response that provides stiffness where needed while maintaining protection margins.
Solution Approach 2:
The patent applies preliminary action by pre-positioning the undulations in the radially outermost working layer during manufacturing. The undulations are designed in advance to be radially outer of points in line with groove centers, creating a pre-established structural configuration that provides both stiffness and protection before the tire encounters ground attacks.
4Strength
If metallic reinforcing elements are used in working layers, then axial stiffness is improved, but weight increases
Solution Approach 1:
The patent uses thin films by applying a thin elastomer coating to the metallic reinforcing elements. The coating thickness is sufficient to provide grip and protection functions but thin enough to minimize additional weight. The working layer structure uses the metallic cords as thin reinforcement elements embedded in the rubber matrix.
Data Source
AI summary
Tire comprising major grooves with a depth at least equal to 4 mm and with a width at least equal to 1 mm. The radially outermost working layer (41) comprises at least one undulation (412). The undulation (412) is such that the undulation (412) portion of the working layer (41) represents at least 10% of the surface of the working layer (41), has an amplitude of at least 1 mm and is radially on the outside of the points of the working layer (41) that are in line with the bottom face (243) of the major groove (24) closest (412). All the layers of material (3, 6, 7) making up the radial stack of the crown structure (S) have mean surfaces parallel to that of the radially outermost working layer (41).