Pneumatic Tire Geometry for Fuel Economy and Stability
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Solution Overview
Problem
Conventional pneumatic tires that reduce rolling resistance to improve fuel economy often compromise steering stability due to narrow ground contact width, and attempts to enhance stability through reduced groove area ratios lead to increased tire weight, making it difficult to achieve both performance metrics simultaneously.
Innovation Solution
A pneumatic tire design with a narrow width and large diameter, featuring a specific tread profile partitioned into regions with optimized cross-sectional areas and lengths, a groove area ratio of 25% or less, and reinforced layers to enhance cornering force and stability, while minimizing weight and rolling resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the total width and forward projection area of the pneumatic tire are decreased to reduce air resistance, then fuel economy is improved, but the ground contact width becomes narrow and steering stability is reduced
Solution Approach 1:
The patent changes the geometric parameters of the tire by decreasing the total width SW and increasing the outer diameter OD to satisfy SW/OD≤0.3, thereby reducing air resistance and improving fuel economy while maintaining steering stability through optimized ground contact characteristics
Solution Approach 2:
The patent preliminarily optimizes the tread groove design by setting the groove area ratio GR to 25% or less before the tire enters service, ensuring both fuel economy performance and steering stability are achieved from the outset without requiring operational adjustments
2Stability of the object's composition
If the groove area ratio of the tread portion is reduced to ensure steering stability, then cornering force is improved, but tire weight increases and fuel economy cannot be sufficiently realized
Solution Approach 1:
The patent optimizes the groove area ratio GR to 25% or less, finding the optimal parameter value that simultaneously achieves steering stability and minimizes tire weight for fuel economy performance
3Use of energy by moving object
If the ground contact width is made narrow to reduce air resistance, then fuel economy is improved, but cornering force is reduced and steering stability deteriorates
Solution Approach 1:
The patent optimizes the ratio of ground contact length to ground contact width by adjusting tire dimensions to satisfy SW/OD≤0.3, creating a ground contact pattern that generates sufficient cornering force despite the narrow width through increased length
Solution Approach 2:
The patent compensates for the narrow ground contact width by increasing the ground contact length in the circumferential direction, utilizing another dimension to maintain the overall ground contact area and cornering force
Data Source
AI summary
A pneumatic tire includes a tread portion, sidewall portions, bead portions, and has at least one carcass layer disposed between the pair of bead portions. The ratio SW/OD between the total tire width SW and the tire external diameter OD satisfies the relationship SW/OD≤0.3. A first region A is defined between a pair of first boundary lines (L1, L1), second regions B are defined between a first boundary line (L1) and a second boundary line (L2), and third regions C are defined on the bead toe side of the second boundary lines (L2). Defining SA, SB, and SC as the cross-sectional area (mm2) of the first region A to the third region C, and defining the peripheral lengths (mm) of the first region A to third region C along the tire inner surface as a, b, and c, respectively, the relationship 7.5≤SA/a≤11.5 is satisfied.