Pneumatic Tire Center Rib Rubber Modulus Gradient
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Solution Overview
Problem
Pneumatic tires face a trade-off between lane change stability and cornering/braking performance due to the rigidity of the center rib, where a wide rib enhances lane change stability but deteriorates cornering and braking, and a narrow rib improves cornering and braking but compromises lane change stability.
Innovation Solution
A pneumatic tire design with a center rib width of at least 10% of the grounding width, featuring an interface between outside rubber with a high tension modulus and inside rubber with a low tension modulus, where the tension modulus difference is at least 15% and the hardness difference is within ±3°, to promote strain on the grounding surface and maintain rigidity, thereby enhancing cornering stability and braking performance while securing lane change stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If the center rib is made wide to enhance lane change stability, then the rigidity of the center portion is improved, but the cornering stability and braking performance are deteriorated due to poor grounding property
Solution Approach 1:
The tread rubber is divided into multiple regions (first, second, third, and fourth regions) with different rubber compositions and hardness values. The first and second regions have higher hardness for lane change stability, while the third and fourth regions have lower hardness for cornering and braking performance, allowing each local area to optimize its function
Solution Approach 2:
The patent uses composite rubber materials with different physical properties in different regions of the tread. By combining rubber compositions with varying hardness values (first rubber composition for higher hardness, second rubber composition for lower hardness), the system achieves both rigidity for stability and flexibility for grip
2Reliability
If the center rib is made narrow to improve cornering stability and braking performance, then the grounding property is improved, but the lane change stability is lowered due to reduced rigidity
Solution Approach 1:
The tread rubber is divided into multiple regions (first, second, third, and fourth regions) with different rubber compositions and hardness values. The first and second regions have higher hardness for lane change stability, while the third and fourth regions have lower hardness for cornering and braking performance, allowing each local area to optimize its function
Solution Approach 2:
The patent uses composite rubber materials with different physical properties in different regions of the tread. By combining rubber compositions with varying hardness values (first rubber composition for higher hardness, second rubber composition for lower hardness), the system achieves both rigidity for stability and flexibility for grip
3Reliability
If the rubber hardness difference between outside and inside of the tire is increased to enhance cornering stability, then the grip is improved, but the rigidity fluctuation in the center rib increases causing lane change stability to deteriorate
Solution Approach 1:
The tread rubber is divided into multiple regions (first, second, third, and fourth regions) with different rubber compositions and hardness values. The first and second regions have higher hardness for lane change stability, while the third and fourth regions have lower hardness for cornering and braking performance, allowing each local area to optimize its function
Solution Approach 2:
The tread rubber is segmented into distinct regions with different properties. The first region (outside, high latitude) and second region (inside, high latitude) are separated from the third region (outside, low latitude) and fourth region (inside, low latitude), each with optimized rubber compositions for their specific functional requirements
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 design achieves excellent cornering stability and braking performance while maintaining good lane change stability by moderating the center rib's width and tension modulus difference, suppressing rigidity fluctuations and ensuring sufficient grip during cornering and braking.
Implementation Method 1
an outside rubber (5o) having a relatively high tension modulus and an inside rubber (5i) having a relatively low tension modulus, by setting an interface (10) formed in the center rib (6) along a tire diametrical direction to a boundary
Data Source
Figure 1
Figure 2~4
Figure 5~7
AI summary
A pneumatic tire has a center rib extending along a tire circumferential direction in a center portion of a tread surface. A width of the center rib is equal to or more than 10 % of a grounding width. An outside rubber having a relatively high tension modulus is arranged at the outside relative to a vehicle and an inside rubber having a relatively low tension modulus is arranged at the inside relative to a vehicle, by setting an interface formed in the center rib along a tire diametrical direction to a boundary. 300 % tension modulus Mo and a rubber hardness Ho of the outside rubber, and 300 % tension modulus Mi and a rubber hardness Hi of the inside rubber satisfy the following relationship: Mo-Mi/Mo≥0.15 Ho-Hi≤±3°.