Belt-Layer Rubber Composition for Stable Pneumatic Tire Handling
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Solution Overview
Problem
Conventional pneumatic tires reduce rolling resistance but compromise steering stability and durability, particularly experiencing significant changes in steering stability between low-speed and high-speed running, and lack sufficient durability.
Innovation Solution
A pneumatic tire design featuring a belt layer with a specific rubber composition and geometry, where the ratio of loss tangent to complex elastic modulus (tan δ/E*) is between 0.002 and 0.017, and the tire satisfies specific formulas relating to cross-sectional width, outer diameter, and virtual volume, to maintain stability and durability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the rolling resistance is reduced by conventional rubber composition formulation, then fuel efficiency is improved, but steering stability changes significantly between low-speed and high-speed running and durability is insufficient
Solution Approach 1:
The patent applies parameter changes by precisely controlling the ratio of loss tangent to complex elastic modulus (tan δ/E*) of the belt layer rubber composition within 0.002 to 0.017, and by controlling the tire geometry parameters (outer diameter Dt, cross-sectional width Wt, virtual volume V) to satisfy specific formulas. This multi-parameter optimization resolves the contradiction by achieving both low rolling resistance and stable steering characteristics across different speeds.
Solution Approach 2:
The patent uses composite materials by formulating a specific rubber composition for the belt layer that combines multiple rubber components and additives to achieve the target tan δ/E* ratio. This composite approach allows simultaneous optimization of rolling resistance and steering stability that cannot be achieved with single-material formulations.
2Loss of energy
If the rolling resistance is reduced, then fuel efficiency is improved, but durability is insufficient
Solution Approach 1:
The patent resolves this contradiction by changing the material parameters of the belt layer rubber composition, specifically controlling the tan δ/E* ratio within 0.002 to 0.017. This parameter optimization enables the tire to maintain low rolling resistance while achieving sufficient durability for long-term use.
Solution Approach 2:
The patent applies beforehand cushioning by designing the belt layer with specific rubber composition and geometric parameters that preemptively protect against durability issues. The controlled tan δ/E* ratio and geometry formulas create a structure that resists degradation under operating conditions, ensuring long service life.
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 changes in steering stability between low-speed and high-speed running while enhancing durability, ensuring improved handling performance and longevity.
Implementation Method 1
the ratio of loss tangent (tan δ) to complex elastic modulus (E*: MPa), (tan δ/E*), of the rubber composition constituting the belt layer, measured under the conditions of 70° C., frequency of 10 Hz, initial strain of 5%, and dynamic strain rate of 1%
Data Source
AI summary
Provided is a pneumatic tire with which any change in steering stability between low-speed running and high-speed running is sufficiently minimized, and durability is also sufficiently improved. This pneumatic tire has a belt layer radially inward of the tread portion, wherein the ratio (tan δ/E*) of the loss tangent (tan δ) to the complex elastic modulus E*(MPa) of the rubber composition constituting the belt layer, as measured under the conditions of 70° C., frequency 10 Hz, initial distortion 5%, and dynamic distortion rate 1%, is 0.002 to 0.017 (inclusive), and the (formula 1) and (formula 2) are satisfied, where Wt (mm) is the cross-sectional width of the tire, Dt (mm) is the outside diameter, and the virtual volume V (mm3) is the volume of the space occupied by the tire, when the tire is installed on a standardized rim and the internal pressure is 250 kPa.1700≤(Dt2×π/4)/Wt≤2827.4 (formula 1)[(V+1.5×107)/Wt]≤2.88×105 (formula 2)