Layered Sidewall Rubber for Conductive and Durable Pneumatic Tires
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Solution Overview
Problem
Existing pneumatic tires face challenges in achieving a balance between conductivity, fuel efficiency, durability, and ozone resistance, as conductive rubber layers can lead to local deformation and decreased durability, and lack adequate ozone resistance measures.
Innovation Solution
A pneumatic tire design featuring a carcass with a sidewall rubber formed by laminating multiple layers, including a sidewall outermost layer and a sidewall inner layer, with specific volume resistivity, antioxidant mass ratio, and storage modulus ratios to enhance conductivity, fuel efficiency, and ozone resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conductive rubber layer is provided between sidewall rubber and carcass, then conductivity is improved, but local deformation occurs and durability decreases
Solution Approach 1:
The invention changes the physical parameters of the rubber layers by controlling the storage modulus ratio (E'swin/E'pc) between sidewall inner layer rubber and ply coating rubber to be 0.5 < ratio ≤ 1.0. This parameter optimization ensures that the rubber layers have compatible stiffness characteristics, preventing local deformation while maintaining conductivity pathways through the tire structure.
Solution Approach 2:
The invention uses composite rubber material structures with multiple layers (sidewall outermost layer, sidewall inner layer, and ply coating rubber) having different but coordinated properties. The composite structure allows the sidewall inner layer to provide conductivity while the optimized modulus ratio ensures compatibility with the carcass, eliminating the harmful local deformation effect.
2Reliability
If conductive rubber is used in sidewalls and ply coating, then static electricity accumulation is prevented, but rolling resistance increases and fuel efficiency decreases
Solution Approach 1:
The invention applies conductive properties locally and selectively to specific rubber layers (sidewall inner layer and ply coating rubber) rather than throughout the entire tire. By concentrating conductivity requirements in these specific locations and optimizing their modulus ratio, the invention maintains necessary conductivity while minimizing the volume of conductive material that would otherwise increase rolling resistance.
Solution Approach 2:
The invention optimizes the storage modulus parameter of the rubber layers to achieve a balance between conductivity and rolling resistance. By setting the modulus ratio E'swin/E'pc within the specific range (0.5 < ratio ≤ 1.0), the invention ensures that the conductive rubber layers have sufficient flexibility to reduce hysteresis losses while maintaining their conductivity function.
3Ease of manufacture
If conventional tire structures are used, then manufacturing is simple, but ozone resistance is insufficient
Solution Approach 1:
The invention employs a composite multi-layer rubber structure where each layer (sidewall outermost layer, sidewall inner layer, and ply coating rubber) can be formulated with specific ozone-resistant compounds and antioxidants. This composite approach provides enhanced ozone resistance compared to conventional single-layer structures, while the layered construction remains compatible with existing tire manufacturing processes.
Solution Approach 2:
The invention incorporates ozone-resistant properties into the rubber compound formulation during the manufacturing preparation stage. By pre-formulating the rubber layers with ozone-resistant additives and optimizing their structural parameters before assembly, the invention provides built-in protection against ozone degradation without requiring additional manufacturing steps or complex assembly procedures.
Data Source
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AI summary
Provided is a pneumatic tire excellent in fuel efficiency, durability, and ozone resistance while having high conductivity. A pneumatic tire comprises a carcass and a sidewall rubber, wherein the sidewall rubber is formed by laminating two or more layers of rubbers including a sidewall outermost layer rubber at a tire outer surface and a sidewall inner layer rubber closer to a tire inner surface than the sidewall outermost layer rubber is, the sidewall inner layer rubber has a thickness of 0.1 mm to 1.2 mm, a mass ratio of an anti oxidant in the sidewall inner layer rubber is 1.2 mass% or more, a proportion of the mass ratio of the anti oxidant in the sidewall inner layer rubber to a mass ratio of an anti oxidant in the sidewall outermost layer rubber is 0.7 to 2.0, and E'swout/E'swin is more than 0.57 and less than 1.5.