Tire Shoulder Groove Layout for Low Rolling Resistance
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Solution Overview
Problem
Current tire designs face challenges in reducing rolling resistance without compromising grip performance on wet roads, as strategies to decrease rolling resistance often lead to decreased Wet performance or result in damage such as belt edge loosening.
Innovation Solution
A tire design featuring circumferential narrow grooves with specific dimensions and placement between shoulder circumferential grooves and the outer layer, utilizing a base portion with lower loss tangent to reduce compressive strain and heat generation, while maintaining grip performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a crosslinked rubber with low heat generation properties is used for the cap portion, then rolling resistance is reduced, but grip performance on wet road surface is decreased
Solution Approach 1:
The tread is divided into cap portion and base portion with different material properties. The cap portion uses rubber optimized for grip performance while the base portion uses crosslinked rubber with low heat generation properties. This local differentiation allows each region to perform its specific function optimally without compromising overall performance.
2Loss of energy
If circumferential narrow grooves are formed on shoulder land portions, then rolling resistance is reduced, but damage such as belt edge loosening may occur
Solution Approach 1:
The groove width is locally varied: narrow grooves (first width) are formed in the shoulder land portions to reduce rolling resistance, while wider grooves (second width) are formed in the central land portion. This local differentiation allows the narrow grooves to reduce strain and rolling resistance without compromising the structural integrity and belt edge loosening resistance that would be compromised by uniformly narrow grooves across the entire tread.
Solution Approach 2:
The groove width parameter is changed based on position: the groove width in shoulder land portions is set to a first width that is smaller than the groove width in the central land portion (second width). This parameter variation optimizes rolling resistance reduction while preventing belt edge loosening damage.
3Loss of energy
If the number of components is decreased, then rolling resistance is reduced, but structural integrity and durability may be compromised
Solution Approach 1:
The cap portion and base portion are merged into a single integrated tread structure. The cap portion and base portion are bonded to each other, forming a unified component that reduces the number of separate parts while maintaining the functional benefits of differentiated material properties for reduced rolling resistance and preserved structural integrity.
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 achieves reduced rolling resistance without compromising Wet performance and minimizes the risk of damage like belt edge loosening, thereby improving fuel efficiency and maintaining steering stability.
Implementation Method 1
a loss tangent of the base portion at 30°C is lower than a loss tangent of the cap portion at 30°C, the loss tangent at a temperature of 30°C is measured using a viscoelasticity spectrometer
Data Source
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AI summary
A tire 2 includes a tread 4 and a belt 14 including inner and outer layers 38 and 40. Each end of the outer layer 40 is located axially inward of an end of the inner layer 38. A circumferential narrow groove 48 is formed on each shoulder land portion 46s so as to continuously extend in a circumferential direction. A groove width of the circumferential narrow groove 48 is smaller than that of a shoulder circumferential groove 44s. The circumferential narrow groove 48 is located between the shoulder circumferential groove 44s and the end of the outer layer 40 in an axial direction. A ratio of a distance in the axial direction from the shoulder circumferential groove 44s to the circumferential narrow groove 48 to a distance in the axial direction from the shoulder circumferential groove 44s to the end of the outer layer 40 is 15% to 55%.