Asymmetric Tread Layout for Dry-Road Steering Stability
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Solution Overview
Problem
Existing tires face challenges in maintaining steering stability on dry roads, particularly due to the configuration of crown land and middle land portions which do not adequately distribute pressure and contact width for optimal performance.
Innovation Solution
A tire design featuring a specific configuration of tread portions with varying widths and sipes, including a crown land portion and two middle land portions, where the widths satisfy specific ratios and are equipped with longitudinal sipes and undercut recesses in the circumferential grooves to enhance rigidity and contact surface distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If the crown land portion and middle land portions are formed with continuous ribs extending in the tyre circumferential direction, then noise during running is suppressed, but steering stability on dry roads is insufficient
Solution Approach 1:
The patent applies local quality by creating asymmetric width ratios in different land portions. The first middle land portion has a width W1m satisfying 0.95 ≤ W1m/Wc ≤ 1.05, while the second middle land portion has a width W2m satisfying 0.90 ≤ W2m/Wc ≤ 0.98. This local variation in dimensions optimizes both noise suppression and steering stability in their respective regions.
Solution Approach 2:
The patent changes the dimensional parameters of the land portions, specifically the width ratios W1m/Wc and W2m/Wc, to optimize performance. By controlling these width parameters within specific ranges, the patent achieves both noise suppression from continuous ribs and improved steering stability through optimized contact patch distribution.
2Reliability
If the land portions are made wider to improve steering stability, then cornering force increases, but ride comfort deteriorates due to increased stiffness
Solution Approach 1:
The patent creates different width ratios for different land portions to balance steering stability and ride comfort. The first middle land portion maintains a width ratio W1m/Wc of 0.95-1.05 for stability, while the second middle land portion uses a narrower ratio W2m/Wc of 0.90-0.98, creating local variations that balance performance and comfort.
Solution Approach 2:
The patent introduces asymmetry by making the width ratios of the two middle land portions different relative to the crown land portion. This asymmetric design allows optimization of cornering force distribution while maintaining ride comfort through varied stiffness characteristics in different regions.
3Ease of manufacture
If the crown land portion has equal width distribution on both sides, then manufacturing is simplified, but cornering force is insufficient due to inadequate pressure distribution
Solution Approach 1:
The patent deliberately creates asymmetric width distribution in the crown land portion by specifying different width ratios for the first and second middle land portions relative to the crown land. This asymmetric configuration optimizes pressure distribution during cornering, generating sufficient cornering force while remaining manufacturable.
Solution Approach 2:
The patent applies local quality by creating specific width ratio relationships in different regions of the crown land portion. The controlled asymmetry in width ratios W1m/Wc and W2m/Wc optimizes local pressure distribution to enhance cornering force generation.
Data Source
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AI summary
A tyre includes a tread portion including first and second tread edges, circumferential grooves, and land portions. The land portions include a crown land portion, a first middle land portion, and a second middle land portion. Under a 50% loaded condition, the first middle land portion, the crown land portion, and the second middle land portion respectively have axial widths Wlm, Wc, and W2m of ground contact surfaces, the widths satisfying the following formula, W1m > Wc > W2m. The crown land portion includes an outer ground contact surface and an inner ground contact surface. The outer ground contact surface and the inner ground contact surface respectively have widths Wco and Wci in the tyre axial direction, the widths satisfying the following formula, Wco > Wci.