Heavy Duty Tire Tread Base Layer Design
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Solution Overview
Problem
Heavy duty tires face challenges in reducing rolling resistance while maintaining weather resistance and preventing damage such as belt edge loose and superficial cracking, particularly due to the susceptibility of natural rubber to ozone deterioration and heat generation.
Innovation Solution
A heavy duty pneumatic tire design featuring a tread with a base layer and cap layer, where the base layer covers the belt and has a loss tangent of 0.06 or less, and a complex elastic modulus of 3 MPa or more, with a boundary between the layers exposed on the side surfaces, ensuring a sufficient volume and appropriate rigidity to reduce rolling resistance and prevent cracking.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If natural rubber is used for the base layer to suppress heat generation, then rolling resistance is reduced, but weather resistance deteriorates due to ozone susceptibility
Solution Approach 1:
The patent applies different rubber compositions to different regions of the base layer. Specifically, it uses at least two types of rubber compositions with different properties in the base layer, allowing one region to provide low heat generation (suppressing rolling resistance) while another region provides ozone resistance (maintaining weather resistance). This local differentiation resolves the contradiction between energy loss reduction and reliability maintenance.
2Loss of energy
If the base layer is exposed on the side surface to reduce rolling resistance, then energy loss is reduced, but the base layer becomes susceptible to cracking
Solution Approach 1:
The patent exposes the base layer on the side surface only in specific regions while maintaining coverage in other areas. This selective exposure allows the tire to achieve reduced rolling resistance through base layer exposure in appropriate zones while preventing cracking by maintaining protective coverage in regions where exposure would be harmful.
Solution Approach 2:
The patent uses composite rubber compositions in the base layer, combining materials with different properties. This composite structure allows the base layer to simultaneously achieve low rolling resistance through controlled exposure while maintaining crack resistance through the inherent properties of the composite material formulation.
3Reliability
If the base layer width is increased to prevent belt edge loose, then structural integrity is improved, but rolling resistance increases
Solution Approach 1:
The patent varies the width of the base layer across different regions of the tire. By making the base layer wider in specific areas and narrower in others, it prevents belt edge loose in critical regions while minimizing the overall increase in rolling resistance that would result from a uniformly wide base layer.
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 a reduction in rolling resistance while suppressing damage like belt edge loose and superficial cracking, maintaining good weather resistance and structural integrity.
Implementation Method 1
The base layer has a loss tangent of 0.06 or less
Data Source
Figure 1
Figure 2
AI summary
To provide a heavy duty pneumatic tire 2 that allows reduction in rolling resistance to be achieved while allowing influence on various performances to be suppressed. In the tire 2, side walls 6 respectively extend from side surfaces 30 of a tread 4 substantially inward in a radial direction. The tread includes a base layer 64 and a cap layer 66. A boundary 68 between the base layer 64 and the cap layer 66 is exposed on the side surfaces 30 of the tread 4. The boundary 68 on the side surfaces 30 is positioned on a radial direction inner side of edges 70 of side walls 6. When an imaginary line that passes through an edge of a belt 14 and extends in an axial direction is set and a portion of the imaginary line that intersects the tread 4 is a line segment (AL), a ratio of a width (BL) of the base layer 64 in a width (EL) of the tread 4, which is represented by a length of the line segment (AL), is 70% or more. The base layer 64 has a loss tangent (TLb) of 0.06 or less.