Pneumatic Tire Carcass Cord Angle for Cornering and Acceleration
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Solution Overview
Problem
Current pneumatic tires face a challenge in achieving a well-balanced combination of cornering performance and acceleration performance, as they tend to compromise on flexibility in the rotational direction due to the envelope structure that enhances lateral stiffness.
Innovation Solution
The design incorporates a carcass with specific angle adjustments of carcass cords relative to the equator plane, along with strategically positioned and angled filler cords, to maintain lateral stiffness while improving rotational flexibility, ensuring sufficient ground-contact surface at various load conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the envelope structure with turned-up portion is used to enhance lateral stiffness, then cornering performance is improved, but rotational flexibility deteriorates
Solution Approach 1:
The carcass cord angle is set to 80-90 degrees specifically in the turned-up portion region, while other regions may have different angles. This localized angle adjustment provides high lateral stiffness where needed (in the turned-up portion) while maintaining rotational flexibility in other areas of the tire
Solution Approach 2:
The carcass cord angle is designed to vary dynamically with tire deformation. When the tire deforms during rotation, the 80-90 degree angle in the turned-up portion allows the structure to adapt, providing flexibility during rotation while maintaining stiffness during cornering
2Adaptability or versatility
If the carcass cord angle is adjusted to improve rotational flexibility, then acceleration performance is enhanced, but lateral stiffness is reduced
Solution Approach 1:
The carcass cord angle is specifically set to 80-90 degrees only in the turned-up portion, while other portions of the carcass can have different angles optimized for their specific functions. This localized approach maintains lateral stiffness in critical areas while providing rotational flexibility where needed
3Strength
If the turned-up portion overlaps the belt to enhance tread stiffness, then high-speed cornering stability is improved, but low-speed deformation capability is reduced
Solution Approach 1:
The carcass cord angle parameter is changed to 80-90 degrees in the turned-up portion, which modifies the mechanical properties of this region. This angle optimization allows the structure to provide both stiffness and deformation capability depending on the loading conditions and speed
Data Source
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AI summary
[Object] Provided is a pneumatic tire 42 having excellent cornering performance and acceleration performance. [Solution] The tire 42 includes a carcass 50 that includes a carcass ply 70. The carcass ply 70 includes carcass cords. An absolute value of an angle of the carcass cords relative to an equator plane is not less than 80° and not greater than 90°. The tire 42 includes a filler 62 that includes an inner portion 92 and an outer portion 94. An end 96 of the inner portion 92 and an end 98 of the outer portion 94 are disposed between an end 108 of a belt 52 and an end 78 of a turned-up portion 72b of the carcass ply 70 in a radial direction. A ratio of a height, in the radial direction, of an apex 68 of a bead 48 to a cross-sectional height of the tire 42 is not less than 45%. A ratio of a height, in the radial direction, of the inner portion 92 to the cross-sectional height, and a ratio of a height, in the radial direction, of the outer portion 94 to the cross-sectional height are not less than 35%.