Pneumatic Tire Sidewall and Chafer Segmentation
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Solution Overview
Problem
Heavy-duty pneumatic tires face challenges in reducing rolling resistance while preventing ply tear loss (PTL) without compromising the tire's appearance quality, as existing designs either concentrate distortion or suffer from weather resistance issues due to the conflicting requirements of low heat generation and wear resistance in the chafer and sidewall materials.
Innovation Solution
A pneumatic tire design featuring sidewalls with a low loss tangent extending between the beads and chafers, where the chafer with a high complex elastic modulus extends outward of the turned-up portion's end, and the sidewall's arc-shaped side surface ensures close contact with the rim, reducing energy loss and inhibiting distortion and crack growth.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a chafer with high complex elastic modulus and high loss tangent is used to withstand rim force and reduce wear, then wear resistance is improved, but energy loss increases and rolling resistance increases
Solution Approach 1:
The chafer is divided into two portions: a first portion with high complex elastic modulus and high loss tangent for wear resistance, and a second portion with low loss tangent for reduced energy loss. This segmentation allows each portion to optimize its material properties for its specific function.
Solution Approach 2:
Different portions of the chafer have different material properties: the first portion (contacting rim) uses rubber with high complex elastic modulus and high loss tangent for wear resistance, while the second portion (away from rim) uses rubber with low loss tangent to reduce energy loss during tire deformation.
2Loss of energy
If the sidewall is made large and the chafer is made small to increase low heat generating rubber proportion, then energy loss is reduced, but distortion concentration occurs near the end of the turned-up portion
Solution Approach 1:
The chafer is segmented into two portions with different material properties and positions. The first portion is positioned near the end of the turned-up portion to provide distortion resistance, while the second portion extends to reduce overall energy loss.
Solution Approach 2:
The first portion of the chafer uses rubber with high complex elastic modulus to resist distortion concentration at the turned-up portion end, while the second portion uses low loss tangent rubber to reduce energy loss in areas less susceptible to distortion.
3Strength
If the chafer extends to a position outward of the end of the turned-up portion to inhibit distortion, then PTL is prevented, but weather resistance deteriorates due to constant air contact and ozone exposure
Solution Approach 1:
The chafer is divided into two portions: the first portion positioned to provide distortion resistance, and the second portion extended to inhibit crack growth. This segmentation allows the second portion to serve as a protective barrier against weathering while the first portion provides structural support.
Solution Approach 2:
The first portion uses rubber optimized for mechanical strength and distortion resistance, while the second portion uses rubber with superior weather resistance properties to protect against ozone and environmental degradation in the exposed area.
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 and inhibited PTL while maintaining excellent appearance quality by optimizing the interaction between the sidewall and chafer materials and their positions, ensuring effective contact with the rim and minimizing distortion and cracking.
Implementation Method 1
Energy loss due to the deformation and restoration is a major factor in generation of rolling resistance of the tire. When a low heat generating rubber (rubber having a low loss tangent) is used for a tire, energy loss can be reduced.
Implementation Method 2
When the tire rolls, a high force is applied to the chafer from the rim. In order to withstand the force, a rubber having a high complex elastic modulus is used for the chafer.
Data Source
Figure 1
Figure 2
AI summary
In a tire 2, chafers 8 each extend from a position axially outward of a corresponding one of beads 10 to a position radially inward of the corresponding one of the beads 10. Sidewalls 6 extend to positions between the beads 10 and the chafers 8, respectively. The chafers 8 extend to positions outward of ends 38 of turned-up portions 44 of a carcass ply 40 in the radial direction. When a side surface 50 represents a portion, of an outer surface of each chafer 8, which contacts with a flange of a rim, an outline of the side surface 50 has an arc C that extends from a heel of the bead 10 portion and projects inward.