Motorcycle Tire Breaker Cord Layout for Stable Cornering Transitions
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Solution Overview
Problem
Current motorcycle tires exhibit suboptimal transient characteristics and cornering performance due to stiffness changes at the boundaries between tread regions during transitions from straight running to cornering and vice versa.
Innovation Solution
A motorcycle tire design featuring a tread portion with a breaker layer composed of aligned breaker cords, where the angle of the cords gradually increases from the crown region to the shoulder regions, enhancing stiffness distribution and cornering power, and a bandless structure with tread rubber directly contacting the breaker layer to maintain optimal stiffness and contact pressure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If stiffness is changed at the boundary between tread regions, then cornering performance is improved, but transient characteristics during shift from straight running to cornering deteriorate
Solution Approach 1:
The breaker cords are arranged with different angles in different regions of the tread portion. Specifically, the breaker cords in the intermediate region have a different angle compared to those in the shoulder region, creating local variations in stiffness that optimize both cornering performance and transient characteristics without abrupt transitions
Solution Approach 2:
The breaker cord arrangement creates a gradient in stiffness properties across the tread width. This dynamic stiffness distribution allows the tire to adapt its mechanical properties during transitions between straight running and cornering, improving transient characteristics while maintaining cornering performance
2Strength
If breaker cords are aligned in the breaker layer, then cornering power is enhanced, but excessive stiffness may degrade performance
Solution Approach 1:
The breaker cord angle varies by region, with the intermediate region having a different angle than the shoulder region. This creates localized stiffness variations that provide cornering power where needed while preventing excessive overall stiffness that would degrade performance
Solution Approach 2:
The angle of the breaker cords is changed across different regions of the tread. By adjusting the cord angle parameter in the intermediate region compared to the shoulder region, the tire achieves optimal cornering power while controlling overall stiffness to prevent performance degradation
Data Source
Figure 1
Figure 2
AI summary
Motorcycle tire 1 having a belt layer 7 in a tread portion 2. The belt layer 7 is formed of a belt ply 7p in which a plurality of belt cords 7c are aligned. Each belt cord 7c has an angle θc relative to a tire circumferential direction at positions Pc of end portions of a crown region Cr, and an angle θs relative to the tire circumferential direction at positions Ps that are distant from end portions 7e of the breaker ply 7p by 5 mm in a tire-axially-inward direction. The angle of the belt cords 7c is gradually increased from the angle θc to the angle θs, and a change rate ((θs-θc)/θc) is not less than 15%.