Pneumatic Tire Carcass Ply Twist Gradient for Dent Prevention

Solution Overview

Problem

Pneumatic tires manufactured using a rigid core method often experience difficulty in dilation when inflated, leading to dents on the outer surface due to enhanced rigidity in certain portions, resulting in a poor appearance.

Innovation Solution

The tire design incorporates carcass cords with a higher number of twists at the side edge portions than at the center, allowing for increased elongation and reduced rigidity in overlap areas, preventing the generation of dents by maintaining uniform dilation during inflation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Stability of the object's composition

If ply pieces are disposed to overlap each other from sidewall portions to the bead portions to absorb the difference in circumferential length, then the cord density of the carcass cords is increased and the rigidity of the carcass ply is enhanced, but the tire becomes difficult to dilate when inflated and dents are generated on the outer surface

Engineering Contradiction:

Improverigidity of the carcass plyVSAvoiddilation uniformity

Core Design Contradiction:

Stability of the object's compositionVSShape

Solution Approach 1:

The patent applies local quality by differentiating the twist numbers of carcass cords based on their position within the ply piece. Specifically, cords at the first and second ends have a first twist number, while cords at the center portion have a second twist number. This creates localized variations in cord properties that address the specific needs of different regions: end cords with higher twist provide flexibility in overlap areas to prevent dents, while center cords maintain appropriate rigidity for structural support.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent implements parameter changes by varying the twist number of carcass cords along the length of the ply piece. The twist number serves as a controllable parameter that directly affects cord elongation characteristics. By increasing the twist number at the ends of the ply piece compared to the center, the patent creates a gradient of mechanical properties that enables uniform dilation while maintaining necessary rigidity in different regions.

Inventive Principle:

Principle #35Parameter changes

2Strength

If the number of twists of carcass cords at the side edge portions is increased to reduce rigidity and prevent dents, then the elongation of cords in overlap portions is improved, but the overall structural strength may be compromised

Engineering Contradiction:

Improvestructural strengthVSAvoiddent generation

Core Design Contradiction:

StrengthVSObject-affected harmful factors

Solution Approach 1:

The patent applies local quality by differentiating the twist numbers of carcass cords based on their position within the ply piece. Specifically, cords at the first and second ends have a first twist number, while cords at the center portion have a second twist number. This creates localized variations in cord properties that address the specific needs of different regions: end cords with higher twist provide flexibility in overlap areas to prevent dents, while center cords maintain appropriate rigidity for structural support.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent implements parameter changes by varying the twist number of carcass cords along the length of the ply piece. The twist number serves as a controllable parameter that directly affects cord elongation characteristics. By increasing the twist number at the ends of the ply piece compared to the center, the patent creates a gradient of mechanical properties that enables uniform dilation while maintaining necessary rigidity in different regions.

Inventive Principle:

Principle #35Parameter changes

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

This design effectively reduces the generation of dents on the tire's outer surface, maintaining the tire's performance and appearance by ensuring uniform rigidity and preventing bulging or dilation issues.

Implementation Method 1

Each ply piece is formed such that the number Te of twists of the carcass cords arranged in at least one of side edge portions, in a circumferential direction, of the ply piece is greater than the number Tc of twists of the carcass cords arranged in a center portion of the ply piece

Methodology Applied

Scientific EffectTwist:

Data Source

PatentEP3090885B1Pneumatic tire

Publication Date: 2019.10.02 SUMITOMO RUBBER INDUSTRIES LTD

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AI summary

A pneumatic tire (1) includes a carcass (6) having at least one carcass ply (6A) that extends from a tread portion (2) through sidewall portions (3) to bead portions (4); the carcass ply (6A) has strip-shaped sheet-like ply pieces (11) which are arranged in a tire circumferential direction, and each of which has a radial length L2 greater than a circumferential length L1 in the tire circumferential direction; each ply piece (11) has a plurality of carcass cords (12) arranged along a longitudinal direction, and the ply piece (11) at least partially overlaps a ply piece (11) adjacent thereto in the tire circumferential direction; each carcass cord (12) is formed by a plurality of strands (17) being twisted together; each ply piece (11 is formed such that the number Te of twists of the carcass cords (12) arranged in at least one of side edge portions (11e), in a circumferential direction, of the ply piece (11) is greater than the number Tc of twists of the carcass cords (12) arranged in a center portion (11c) of the ply piece (11).