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 heavier electric vehicles, where the base layer is more brittle and prone to exposure, leading to potential peeling during high-load conditions.
Innovation Solution
A tire design with a harder cap layer covering a softer base layer, where the cap layer ends are positioned axially inward of the belt ends, and specific cap layer thickness proportions in different land portions are optimized to enhance durability and reduce rolling resistance.
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. The shoulder land portion has a higher cap layer proportion (5.0-9.5) providing harder, more durable rubber for peeling resistance, while the crown land portion has a lower cap layer proportion (1.5-3.5) providing softer rubber for lower rolling resistance. This local differentiation resolves the contradiction between durability and energy loss.
Solution Approach 2:
The tread uses a composite structure with two distinct rubber compositions: a harder cap layer rubber for the outer surface and a softer base layer rubber for the inner layer. This composite material approach allows the harder cap layer to resist tread peeling while the softer base layer reduces rolling resistance, resolving the contradiction between reliability and energy loss.
2Reliability
If the cap layer thickness is increased to prevent base layer exposure, then tread durability is improved, but rolling resistance increases
Solution Approach 1:
The patent varies the cap layer thickness proportion across different tread regions. The shoulder land portion has a high cap layer proportion (5.0-9.5) to prevent base layer exposure and resist peeling, while the crown land portion has a low cap layer proportion (1.5-3.5) to minimize rolling resistance. This local quality differentiation resolves the contradiction between durability and energy loss.
3Loss of energy
If the base layer is made softer to reduce rolling resistance, then rolling resistance is reduced, but tread peeling resistance decreases
Solution Approach 1:
The patent creates a two-layer structure where the base layer is uniformly softer (lower cap layer proportion) to reduce rolling resistance, while the cap layer provides localized hardness where needed. The cap layer proportion varies by region (higher at shoulders, lower at crown) to provide peeling resistance only where the base layer is most vulnerable, resolving the contradiction between energy loss and reliability.
Solution Approach 2:
The tread uses a composite material system with a softer base layer rubber for low rolling resistance and a harder cap layer rubber for peeling resistance. This composite structure allows the softer base layer to reduce energy loss while the harder cap layer compensates for reduced peeling resistance, resolving the contradiction between the two properties.
4Reliability
If the cap layer proportion in the shoulder land portion is increased to prevent peeling, then tread durability is improved, but rolling resistance increases
Solution Approach 1:
The patent concentrates the high cap layer proportion (5.0-9.5) specifically in the shoulder land portion where peeling risk is highest during limit running. The crown land portion maintains a low cap layer proportion (1.5-3.5) for low rolling resistance. This targeted local quality approach resolves the contradiction by providing durability only where needed without sacrificing overall energy efficiency.
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 effectively suppresses tread peeling while maintaining low rolling resistance, ride comfort, and quietness, even under high loads, by ensuring the base layer is adequately covered and the cap layer thickness is strategically distributed to minimize heat generation and exposure.
Implementation Method 1
The cap layer is harder than the base layer
Implementation Method 2
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
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AI summary
A tire 2 includes a tread 4 and a belt 20. Each end BE of a base layer 34 of the tread 4 is located axially inward of an end 20e of the belt 20. The tread 4 includes circumferential grooves 30, thereby forming land portions 32 including a crown land portion 32c, a shoulder land portion 32s, and a middle land portion 32m. A cap layer proportion ARc of the crown land portion 32c is not less than 1.5 and not greater than 3.5. A cap layer proportion ARm of the middle land portion 32m is equal to or higher than the cap layer proportion ARc of the crown land portion 32c. A cap layer proportion ARs of the shoulder land portion 32s is higher than the cap layer proportion ARm of the middle land portion 32m and not less than 5.0 and not greater than 9.5.