Pneumatic Tire Tread Blocks for High-Speed Durability
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Solution Overview
Problem
Conventional studless winter tires experience durability issues at high temperatures and during high-speed running due to low hardness and high sipe density, leading to potential cracks.
Innovation Solution
A pneumatic tire with a tread featuring blocks of high sipe density and specific rubber composition, characterized by a tan δ of 0.179 or less at 100°C and a modulus ratio of 69% or greater at 100°C to room temperature, enhancing durability and ice performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional studless winter tires use low hardness rubber and high sipe density in the tread, then ice performance is improved, but durability at high temperatures and during high-speed running deteriorates due to crack formation
Solution Approach 1:
The patent applies parameter changes by precisely controlling the tan δ at 100° C. to be 0.179 or less and the modulus ratio at 100° C. to room temperature to be 69% or greater. These parameter specifications resolve the contradiction by optimizing the rubber's viscoelastic properties to maintain flexibility for ice grip while preventing excessive softening at high temperatures that leads to cracking.
Solution Approach 2:
The patent uses composite materials by formulating a specific rubber composition containing natural rubber, polybutadiene rubber, and polyisoprene rubber in controlled proportions, along with specific additives. This composite approach allows the tread to exhibit both the low-temperature flexibility needed for ice performance and the high-temperature stability required for durability, resolving the contradiction between these opposing requirements.
2Reliability
If the tread blocks have high sipe density to enhance ice grip, then ice performance is improved, but crack occurrence increases at high temperatures
Solution Approach 1:
The patent applies parameter changes by specifying the sipe density within the range of 0.5 to 2.0 cm/cm² and controlling the rubber composition parameters (tan δ ≤ 0.179, modulus ratio ≥ 69%). This resolves the contradiction by optimizing both the structural parameter (sipe density) and material parameters to achieve adequate ice grip while preventing crack formation through controlled rubber hardness and elasticity at operating temperatures.
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 exhibits improved durability at high temperatures and during high-speed running while maintaining good ice performance, with the rubber composition effectively controlling temperature-dependent modulus changes and sipe density for enhanced durability and grip.
Implementation Method 1
a ratio of a modulus at 100° C. to a modulus at room temperature of 69% or greater
Implementation Method 2
a tan δ at 100° C. of 0.179 or less as determined at an initial strain of 10%, a dynamic strain of 2%, and a frequency of 10 Hz
Data Source
AI summary
The present invention provides a pneumatic tire and a rubber composition for tires, which have improved durability at high temperatures and during high-speed running while ensuring good ice performance. The present invention relates to a pneumatic tire, including a tread, the tread including blocks having an average ripe density of 1.0 cm/cm2 or higher and an average height of 0.6 to 2.0 cm, the blocks containing a rubber composition having a tan δ at 100° C. of 0.179 or less as determined at an initial strain of 10%, a dynamic strain of 2%, and a frequency of 10 Hz, and has a ratio of the modulus at 100° C. to the modulus at room temperature of 69% or greater as determined in accordance with JIS K6251:2010.