Passenger Radial Tire Tread Layout for Stable Contact and Low Drag
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Solution Overview
Problem
Narrow and large diameter pneumatic radial tires for passenger vehicles face issues with ground contact area deterioration due to changes in camber angle, increased ground contact pressure, reduced groove area for drainage, and higher rolling resistance, which affect fuel efficiency and ride comfort.
Innovation Solution
A pneumatic radial tire design with a sectional width less than 165 mm, a SW/OD ratio of 0.26 or less, and a tread pattern featuring grooves with widths of 2 mm or less, combined with block-shaped land portions defined by circumferential and width direction grooves, to maintain a rounded ground contact area and reduce compressive rigidity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the sectional width SW of the tire is reduced to improve fuel efficiency, then air resistance and rolling resistance are reduced, but the ground contact area deteriorates due to changes in camber angle
Solution Approach 1:
The patent applies parameter changes by establishing a specific relationship between sectional width SW and outer diameter OD (SW/OD ≤ 0.26 or OD ≥ -0.0187 × SW² + 1600), transforming the tire geometry parameters to achieve both reduced air resistance and maintained ground contact area stability under camber angle changes
Solution Approach 2:
The patent transitions from considering only sectional width SW to incorporating outer diameter OD as a critical parameter, using the dimensional relationship SW/OD ratio to simultaneously optimize aerodynamic performance and ground contact characteristics
2Loss of energy
If the sectional width SW is reduced to improve fuel efficiency, then air resistance is reduced, but ground contact pressure increases
Solution Approach 1:
The patent changes the geometric parameters by defining specific constraints on SW and OD relationship, which redistributes the load over an optimized contact area, thereby reducing ground contact pressure while maintaining low air resistance
3Reliability
If the groove area is reduced to improve hydroplaning performance, then drainage capability is improved, but the ability to follow uneven road surfaces deteriorates
Solution Approach 1:
The patent applies local quality by creating block-shaped land portions with specific groove patterns in different regions of the tread, where groove width is controlled at 2 mm or less to provide drainage capability while the block structure maintains surface following ability
Solution Approach 2:
The patent segments the tread into block-shaped land portions defined by circumferential and width direction grooves, creating a pattern that balances drainage function with surface conformity while controlling overall groove area
4Loss of energy
If the tread rigidity is increased to reduce strain energy loss, then rolling resistance is reduced, but the coefficient of friction on dry road surfaces decreases
Solution Approach 1:
The patent optimizes tread rigidity by controlling groove width at 2 mm or less and creating block-shaped land portions, which reduces compressive strain energy loss while maintaining adequate friction through the block structure configuration
Data Source
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AI summary
A pneumatic radial tire for passenger vehicles that satisfies a defined relationship between sectional width SW and outer diameter OD of the tire, grooves in a contact patch consisting only of grooves having a groove width of 2 mm or less, and the contact patch includes one or more block-shaped land portion defined by two or more circumferential grooves and two or more width direction grooves. A drop height (or ground contact length relationship, or tread gauge relationship) is also defined.