Tire Tread Cap Layer Layout for Peeling Resistance and Low Rolling Loss
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Solution Overview
Problem
Existing tires face challenges in suppressing tread peeling while minimizing the increase in rolling resistance, particularly in heavy electric vehicles, where higher loads can cause the base layer to become exposed and peel off, leading to potential tire failure.
Innovation Solution
A tire design with a cap layer that is harder than the base layer, having a lower loss tangent at 70°C, and a specific thickness distribution across different land portions, where the cap layer proportion in the shoulder land portion is higher than in the middle and crown land portions, with each end of the base layer located axially inward of the belt ends, and a tread pattern with aligned circumferential grooves to enhance stability and reduce exposure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the cap layer is made harder to prevent tread peeling, then tread durability is improved, but rolling resistance increases
Solution Approach 1:
The patent applies different hardness levels to different regions of the cap layer by varying the silane crosslinked rubber content. The shoulder land portion has higher silane crosslinked rubber content (higher hardness) to prevent tread peeling under high load, while the crown land portion has lower silane crosslinked rubber content (lower hardness) to maintain low rolling resistance during normal rolling. This local differentiation resolves the contradiction between durability and energy loss.
Solution Approach 2:
The patent changes the chemical composition parameter (silane crosslinked rubber content) across different regions of the cap layer. By controlling the silane crosslinked rubber content to be higher in the shoulder land portion and lower in the crown land portion, the patent achieves region-specific hardness optimization that simultaneously improves tread durability and maintains low rolling resistance.
2Loss of energy
If the base layer is made thinner to reduce weight, then rolling resistance is reduced, but tread peeling resistance decreases
Solution Approach 1:
The patent uses a composite structure where the cap layer contains silane crosslinked rubber that forms a three-dimensional crosslinked network. This composite material structure in the cap layer provides exceptional tread peeling resistance even when the base layer is thin, because the crosslinked network in the cap layer compensates for the reduced thickness of the base layer, maintaining reliability while reducing rolling resistance.
3Reliability
If the cap layer thickness is increased to prevent tread peeling, then tread durability is improved, but manufacturing complexity increases
Solution Approach 1:
Instead of uniformly increasing cap layer thickness throughout, the patent applies local quality by varying the silane crosslinked rubber content in different regions. This allows the cap layer to have effective peeling resistance where needed (shoulder land portion) without requiring uniform thickness increase, thereby simplifying manufacturing while maintaining durability.
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 effectively suppresses tread peeling while maintaining low rolling resistance, improving ride comfort, and reducing road noise, ensuring balanced performance in heavy electric vehicles.
Implementation Method 1
a loss tangent at 70° C. of the base layer is lower than a loss tangent at 30° C. of the cap layer
Data Source
AI summary
A tire can include a tread and a belt. Each end of a base layer of the tread can be located axially inward of an end of the belt. The tread can include circumferential grooves, thereby forming land portions including a crown land portion, a shoulder land portion, and a middle land portion. A cap layer proportion ARc of the crown land portion can be not less than 1.5 and not greater than 3.5. A cap layer proportion ARm of the middle land portion can be equal to or higher than the cap layer proportion ARc of the crown land portion. A cap layer proportion ARs of the shoulder land portion can be higher than the cap layer proportion ARm of the middle land portion and not less than 5.0 and not greater than 9.5.