Segmented Tire Tread Layout for Wet Grip Under Low Heat Generation
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Solution Overview
Problem
Existing tires face a challenge in achieving a balance between reducing rolling resistance and maintaining wet performance, as using rubber with low heat generation for the intermediate layer leads to degraded grip force and potential significant degradation of wet performance due to abrasion.
Innovation Solution
A tire design with a tread configuration featuring at least three circumferential grooves, a cap layer, a base layer, and an intermediate layer, where the loss tangent of the intermediate layer is less than that of the cap and base layers, and the ratio of the axial width of the two-layer body portion to the tread width is between 20% and 50%, with the circumferential grooves having groove walls and bottoms formed of the cap layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If rubber with low heat generation is used in the intermediate layer to reduce rolling resistance, then rolling resistance is reduced, but wet performance is significantly degraded due to abrasion
Solution Approach 1:
The tread is divided into three distinct layers: cap layer (high grip force), intermediate layer (low heat generation), and base layer (low heat generation). This segmentation allows each layer to perform its specialized function, with the cap layer providing wet performance and the intermediate/base layers reducing rolling resistance through low heat generation rubber.
Solution Approach 2:
Different regions of the tread have different rubber compositions optimized for their specific functions. The cap layer uses rubber with high grip force properties for wet performance, while the intermediate and base layers use rubber with low heat generation properties for rolling resistance reduction. This local quality differentiation resolves the contradiction by assigning appropriate material properties to specific locations.
2Reliability
If rubber with high grip force is used in the cap layer to maintain wet performance, then wet performance is improved, but heat generation increases
Solution Approach 1:
The tread structure separates the heat generation function from the grip force function by placing high grip force rubber only in the cap layer that contacts the road, while the intermediate and base layers use low heat generation rubber. This segmentation allows the system to achieve both high wet performance and reduced overall heat generation.
Solution Approach 2:
The cap layer is specifically designed with high grip force rubber composition to maximize wet performance at the road contact interface, while the underlying intermediate and base layers use rubber with low heat generation properties. This local quality assignment optimizes each layer's contribution to the overall performance balance.
3Loss of energy
If the intermediate layer is made of rubber with low heat generation, then rolling resistance is reduced, but deviation in grip force between cap layer and intermediate layer increases
Solution Approach 1:
The three-layer structure segments the functional requirements: the cap layer provides high grip force for wet performance, the intermediate layer provides low heat generation for rolling resistance reduction, and the base layer provides structural support. This segmentation accepts and manages the grip force deviation as a trade-off for achieving both low rolling resistance and good wet performance.
Solution Approach 2:
The invention changes the material parameters of each layer to optimize overall performance. The intermediate layer uses rubber with low heat generation properties (low loss tangent) to reduce rolling resistance, accepting that this creates grip force deviation from the cap layer. The base layer uses rubber with even lower heat generation properties to further reduce rolling resistance while providing structural support.
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 reduction of rolling resistance while preventing significant degradation of wet performance due to abrasion, with improved crack and chipping resistance.
Implementation Method 1
A loss tangent of the intermediate layer at 30°C is less than a loss tangent of the cap layer at 30°C and a loss tangent of the base layer at 30°C is less than the loss tangent of the intermediate layer at 30°C
Data Source
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AI summary
In a tire 2, a tread 4 includes a cap layer 38 forming a part of an outer surface of the tire 2, a base layer 40 disposed inwardly of the cap layer 38 in a radial direction, and an intermediate layer 42 disposed between the cap layer 38 and the base layer 40 in the radial direction. A loss tangent of the intermediate layer 42 at 30°C is less than a loss tangent of the cap layer 38 at 30°C and a loss tangent of the base layer 40 at 30°C is less than the loss tangent of the intermediate layer 42 at 30°C. The tread 4 includes at least two three-layer body portions 44 formed of the cap layer 38, the intermediate layer 42, and the base layer 40, and at least one two-layer body portion 46 that is formed of the cap layer 38 and the base layer 40 and disposed between a first three-layer body portion 44a and a second three-layer body portion 44b.