Tire Rubber Composition for Wet Steering Stability and Followability
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The tire described in JP 2014-162242 A easily loses followability to a road surface due to the cap rubber having relatively high rigidity, and it cannot generate a sufficient reaction force due to the low rigidity of the base rubber, resulting in poor steering stability on a wet road surface.
Innovation Solution
A tire with a tread part and sidewall composed of a rubber composition containing a rubber component and vegetable oil, where the average content of vegetable oil in the tread rubber is higher than in the sidewall rubber, and the complex elastic modulus of the cap rubber layer and sidewall rubber are optimized to maintain followability and generate a reaction force.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If the cap rubber is set as a rubber layer having a relatively high rigidity, then the steering stability is improved, but the followability to the road surface is lost
Solution Approach 1:
The patent applies local quality by creating distinct rubber compositions for different regions: the tread part uses a rubber composition with higher vegetable oil content (S1) for followability, while the sidewall uses a composition with lower vegetable oil content (S2) for steering stability. This spatial differentiation of material properties resolves the contradiction between followability and steering stability.
Solution Approach 2:
The patent changes the physical-chemical parameters of the rubber composition, specifically the vegetable oil content and complex elastic modulus, to resolve the contradiction. By controlling S1/S2 > 1.0 and 30°C E*C - 70°C E*SW ≤ 3.0 MPa, the patent optimizes the balance between softness for followability and rigidity for steering stability.
2Stress or pressure
If the base rubber is set as a rubber layer having a relatively low rigidity, then the grounding pressure distribution is improved, but the reaction force generation is insufficient
Solution Approach 1:
The patent applies local quality by assigning different rubber compositions to different components: the tread part (including base rubber) uses a composition optimized for pressure distribution with higher vegetable oil content, while the sidewall uses a composition optimized for reaction force generation with lower vegetable oil content and appropriate elastic modulus.
Solution Approach 2:
The patent uses composite materials by combining rubber components with vegetable oil in specific proportions to create rubber compositions with tailored properties. The tread rubber composition and sidewall rubber composition are both composites with different ratios of vegetable oil to rubber component, allowing simultaneous optimization of pressure distribution and reaction force generation.
3Ease of operation
If the vegetable oil content in the tread rubber is increased, then the followability is improved, but the steering stability deteriorates
Solution Approach 1:
The patent resolves this contradiction by applying local quality through spatial differentiation of vegetable oil content. The tread rubber has higher vegetable oil content (S1) for followability, while the sidewall has lower vegetable oil content (S2) for steering stability, with the ratio S1/S2 > 1.0 ensuring both properties are achieved simultaneously.
Solution Approach 2:
The patent changes the vegetable oil content parameter in different locations to resolve the contradiction. By controlling the vegetable oil content ratio S1/S2 > 1.0 and the elastic modulus difference 30°C E*C - 70°C E*SW ≤ 3.0 MPa, the patent achieves both followability and steering stability.
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 maintains steering stability on a wet road surface over a long period by ensuring followability and generating a sufficient reaction force, thanks to the optimized rubber composition and elastic modulus.
Implementation Method 1
when a complex elastic modulus at 30°C of a cap rubber layer constituting a tread surface is defined as 30°C E*C, in MPa, and a complex elastic modulus at 70°C of the rubber composition constituting the sidewall is defined as 70°C E*SW, in MPa, 30°C E*C - 70°C E*SW is 3.0 MPa or less
Data Source
Figure 1
Figure 2
Figure 3
AI summary
A tire comprising a tread part comprising at least one rubber layer and a sidewall, wherein each of the tread part and the sidewall is composed of a rubber composition comprising a rubber component and a vegetable oil, wherein, an average value of a contents of the vegetable oil based on 100 parts by mass of the rubber component in the tread rubber is greater than a content of the vegetable oil based on 100 parts by mass of the rubber component of the rubber composition constituting the sidewall, and wherein, when a complex elastic modulus at 30°C of a cap rubber layer constituting a tread surface is defined as 30°CE∗C, in MPa, and a complex elastic modulus at 70°C of the rubber composition constituting the sidewall is defined as 70°CE∗SW, in MPa, 30°CE∗C - 70°CE∗SW is 3.0 MPa or less.