Rim Protector Geometry in Pneumatic Tires for Comfort and Rolling Resistance
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Solution Overview
Problem
Existing pneumatic tires face a trade-off between improving ride comfort performance and maintaining rolling resistance performance, as reducing tread rigidity to enhance comfort often deteriorates rolling resistance.
Innovation Solution
A pneumatic tire design featuring a rim protector with specific geometric and material properties, including a rim protector with an inner arcuate surface and a cap rubber with defined hardness, to balance ride comfort and rolling resistance by minimizing bead portion deformation and energy loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the rigidity of the tread portions is reduced to improve ride comfort performance, then ride comfort performance is improved, but frictional resistance during running increases, hereby deteriorating rolling resistance performance
Solution Approach 1:
The patent applies local quality by differentiating the rubber hardness between different regions of the tire. The cap rubber forming the ground contact surface has a specific hardness range (50-75 degrees Shore A) to optimize comfort, while the tread portion maintains higher rigidity to control rolling resistance. This regional differentiation allows each part to perform its specific function optimally without compromising the other.
Solution Approach 2:
The tire structure is segmented into distinct functional regions with different material properties. The cap rubber is separated as a distinct component with specific hardness requirements, while the tread portion, sidewall, and bead portion each have their own structural characteristics. This segmentation allows independent optimization of ride comfort (through cap rubber hardness) and rolling resistance (through tread rigidity).
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 improves ride comfort while effectively suppressing the deterioration of rolling resistance performance, achieving a balanced performance in both aspects.
Implementation Method 1
a cap rubber that forms a ground contact surface of the tread portion and has a rubber hardness B (degrees)
Data Source
Figure 1
Figure 2
Figure 3A~3B
AI summary
A pneumatic tire 1 includes a cap rubber (2C) having a rubber hardness (B). In the meridional cross-section of the tire in the standard state, a rim protector (10) having a top portion (11) protruding outward of the tire is formed on an outer surface (4A) of the first bead portion (4). The rim protector 10 includes an inner arcuate surface (12) having a radius of curvature C (mm), which extends from the top portion (11) toward the inner side in the tire radial direction and has a center (12c) located outward of the tire. When (H) is defined as the separation distance in the tire axial direction between the top portion (11) and the radial line (RL) that defines the rim width of the standard rim (R), the following expression (1) is satisfied: 12.8≤H×B/C≤93.5