Pneumatic Tire Width-Diameter Ratio for Steering Stability
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Solution Overview
Problem
Pneumatic tires face a trade-off between reducing rolling resistance and maintaining steering stability, as narrowing the tire width to decrease air resistance leads to reduced ground contact width and cornering force, compromising steering stability.
Innovation Solution
A pneumatic tire design with a total width to outer diameter ratio of SW/OD ≤ 0.3, featuring a tread profile formed by connecting arcs with specific radii of curvature, and a developed tread width to total width ratio of 0.8 ≤ TDW/SW < 1, along with a depression angle of 1.5° ≤ θ ≤ 4.5°, which increases the developed tread width and maintains a larger outer diameter to enhance steering stability while reducing rolling resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the total width of the pneumatic tire is reduced to decrease the front projected area and air resistance, then rolling resistance is reduced, but the ground contact width is reduced and cornering force is reduced, compromising steering stability
Solution Approach 1:
The patent transitions from optimizing only the total width (one dimension) to optimizing the ratio between total width and outer diameter (relating two dimensions). By controlling SW/OD ≤ 0.3, the design allows the outer diameter to be larger while the total width is reduced, effectively using the outer diameter dimension to compensate for the reduced ground contact width and maintain steering stability while achieving lower rolling resistance through reduced air resistance.
2Use of energy by moving object
If the ground contact width is reduced to lower rolling resistance, then fuel economy is improved, but the cornering force is reduced and steering stability deteriorates
Solution Approach 1:
The patent changes the geometric parameters of the tire, specifically the ratio SW/OD ≤ 0.3 and the tread profile curvature radii ratios. By adjusting these parameters, the design achieves a configuration where the reduced total width lowers rolling resistance and improves fuel economy, while the specific tread profile geometry (with Rc/Rsh ≥ 5 and L/(TDW/2) ≤ 0.8) compensates for the reduced ground contact width to maintain adequate cornering force and steering stability.
3Reliability
If the outer diameter is increased to maintain load capacity with reduced total width, then the ground contact length becomes longer improving wet performance, but the ground contact width is reduced affecting cornering force
Solution Approach 1:
The patent applies local quality by designing different regions of the tread profile with specific geometric characteristics. The tread profile includes a center portion arc, side portion arcs, and shoulder side arcs with different radii of curvature. The center portion has a larger radius (Rc) while the shoulder portions have smaller radii (Rsh), creating a local geometric configuration that optimizes both the ground contact length (improving wet performance) and the ground contact width distribution (maintaining cornering force) in different regions of the tire footprint.
Data Source
AI summary
The present technology pertains to a pneumatic tire (1) comprising: a pair of bead portions (2); sidewall portions (3) connected to the pair of bead portions; and a tread portion (10) connected to the sidewall portions. A ratio between a total width (SW) and an outer diameter (OD) of the pneumatic tire satisfies the relationship SW/OD≤0.3. Moreover, if the length along a tread profile (12) from a first side second reference point (Q1) to a second side second reference point (Q2) is the developed tread width (TDW), and an angle formed between a straight line that connects the second reference points and the profile center (cc), and a straight line parallel to the tire width direction is an amount of depression (θ), the following relationships are satisfied: 0.8≤TDW/SW<1, and 1.5°≤θ≤4.5°.