Asymmetric Tire Tread Rigidity for Cornering Torque
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Solution Overview
Problem
Conventional pneumatic radial tires for passenger cars do not effectively improve cornering performance by quickly shifting to a revolution running state during cornering, particularly for vehicles with front engine front drive, due to uneven load distribution and lack of self-aligning torque (SAT) generation.
Innovation Solution
A pneumatic radial tire design featuring an asymmetric tread pattern with varying rigidity in circumferential and axial directions between outer and inner shoulder land regions, along with specific groove configurations to enhance self-aligning torque, ensuring the tire's SAT meets the required criteria for improved cornering performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional symmetric tread patterns are used, then manufacturing is simple and structure is uniform, but self-aligning torque is insufficient and cornering performance is poor
Solution Approach 1:
The tread pattern employs asymmetric design where the outer shoulder land region has different rigidity characteristics compared to the inner shoulder land region. Specifically, the outer shoulder land region is designed with higher rigidity in the tire circumferential direction to generate sufficient self-aligning torque during cornering, while the inner shoulder land region has lower rigidity to maintain contact with the road surface. This asymmetric configuration directly addresses the insufficient SAT problem in conventional symmetric tires.
Solution Approach 2:
Different regions of the tread pattern are assigned different rigidity properties to fulfill specific functions. The outer shoulder land region is localized with high circumferential rigidity for SAT generation, while the inner shoulder land region maintains lower rigidity for road contact stability. This local differentiation of mechanical properties enables the tire to simultaneously achieve cornering performance and contact stability without requiring complete structural redesign.
2Reliability
If outer shoulder land region rigidity is increased to enhance self-aligning torque, then cornering performance improves, but overall tire flexibility may be reduced
Solution Approach 1:
The patent applies local quality by concentrating high rigidity requirements specifically in the outer shoulder land region while maintaining lower rigidity in the inner shoulder land region. This localized approach ensures that the SAT-generating region has the necessary stiffness, while other regions retain flexibility for overall tire compliance and road contact, thus resolving the contradiction between localized rigidity needs and global flexibility.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The tire design effectively increases self-aligning torque, allowing vehicles to transition to a revolution running state more quickly during cornering, thereby enhancing cornering performance and stability.
Implementation Method 1
tread rubber of a ground contacting surface (P) is elastically deformed, therefore, lateral CF (cornering force) is generated
Data Source
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AI summary
A pneumatic radial tire 1 for a passenger car comprises a carcass 6 having a radial structure, a belt layer 7, and a tread portion 2. The tread portion 2 has an outer tread edge (To) and an inner tread edge (Ti). A tread pattern is formed in an asymmetric shape with respect to a tire equator (C). The tread portion 2 is divided into a plurality of circumferential land regions by a plurality of main grooves 10. The circumferential land regions include an outer shoulder land region 16, an inner shoulder land region 17, and a middle land region 18 arranged therebetween. The outer shoulder land region 16 is larger than the inner shoulder land region 17 with respect to rigidity in a tire circumferential direction and the rigidity in a tire axial direction.