Pneumatic Tire Carcass Cord Layout for Strain Concentration Control
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Solution Overview
Problem
Pneumatic tires experience durability deterioration due to strain concentration between the tread part and the side part during running, particularly when carcass cord extending directions are not optimally controlled.
Innovation Solution
A pneumatic tire design with specific inequalities governing the angles and distances of carcass and reinforcing layer cords, including a carcass composed of at least one carcass ply and a reinforcing layer with a single inner-side reinforcing layer ply, where A2 - A1 > 0, Tb / Ta > 0.50, and 70°CE*i > K / (A2 - A1 × Tb - 0.5 × Ta, with K = 6.5, to manage cord inclinations and thicknesses for improved durability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If carcass cords are flexed by controlling the extending direction to improve tire performance, then durability deteriorates due to strain concentration between the tread part and the side part
Solution Approach 1:
The patent applies local quality by differentiating the cord arrangement in different regions of the tire. Specifically, the tread part uses cords with a first extending direction optimized for ground contact and load bearing, while the side part uses cords with a second extending direction optimized for flexibility and strain distribution. This regional differentiation allows each part to have the cord orientation best suited for its specific functional requirements, thereby improving overall durability while preventing strain concentration at the transition zone.
Solution Approach 2:
The patent transitions from a single-dimension cord arrangement (uniform extending direction) to a multi-dimensional approach by varying the cord extending direction across different spatial regions of the tire. By controlling the angle and orientation of cords in the tread part versus the side part, the invention adds dimensional complexity to the cord layout, enabling optimized performance in both ground contact and lateral flexibility without compromising durability.
2Stability of the object's composition
If carcass cords extend in a fixed direction to maintain structural integrity, then flexibility and weight reduction are compromised
Solution Approach 1:
The patent segments the carcass cord structure into distinct regions with different extending directions. The tread part employs cords oriented for structural stability and load bearing, while the side part uses cords oriented for flexibility and weight reduction. This segmentation allows each region to be optimized independently, maintaining structural integrity where needed while reducing weight and improving flexibility in non-critical areas.
3Reliability
If the extending direction of carcass cords is changed to optimize performance, then manufacturing precision requirements increase
Solution Approach 1:
The patent employs parameter changes by defining specific extending direction angles for cords in different regions. The tread part cords are oriented at a first angle range optimized for ground contact, while side part cords are oriented at a second angle range optimized for flexibility. By establishing clear parameter specifications for cord orientation in each region, the invention achieves optimized performance while providing manufacturable guidance for cord placement precision.
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 suppresses durability deterioration by managing strain concentration through controlled cord directions and thicknesses, enhancing flexibility and reducing tire weight.
Implementation Method 1
70°CE*i represents a complex elastic modulus at 70°C, in MPa, of a rubber composition constituting the inner liner
Data Source
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AI summary
Provided is a pneumatic tire comprising a carcass, an inner liner, and at least one reinforcing layer, wherein A1, A2, Ta, Tb, 70°CE*i, and K satisfy the following inequalities, A2−A1>0 Tb/Ta>0.50 70°CE*i>K/A2−A1×Tb−0.5×Ta (provided that K is 6.5) where A1 represents an angle of carcass cord inclined from a tire circumferential direction on a tire center line, A2 represents an angle of carcass cord inclined from the tire circumferential direction at a tire maximum width position, Ta represents a distance from a tire inner surface to a carcass cord on the tire center line, Tb represents the distance on a tire width direction end of the inner-most reinforcing layer ply, 70°CE*i represents a complex elastic modulus of the inner liner, and K represent a constant.