Kart Tire Reinforcing Layer for Buckling-Resistant Cornering

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Solution Overview

Problem

Racing kart tires face challenges in maintaining grip force and steering stability due to buckling issues caused by centrifugal forces during high-speed turns, which are exacerbated by the lack of a belt and lower internal pressure compared to passenger car tires.

Innovation Solution

A tire design featuring a bias carcass structure with a reinforcing layer composed of circumferentially aligned cords positioned between the equatorial plane and the tread's outer end, enhancing the tread's rigidity while maintaining flexibility at the inner end to prevent buckling and ensure a larger ground-contact area.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If the rigidity of the carcass is increased to prevent buckling, then buckling is suppressed, but the rigidity of side portions increases and steering stability decreases

Engineering Contradiction:
Improverigidity of tread portionVSAvoidsteering stability
Core Design Contradiction:
StrengthVSStability of the object's composition

Solution Approach 1:

The patent applies local quality by providing a reinforcing layer only in the radial direction at the tread portion, while maintaining the bias structure elsewhere. This localized reinforcement increases tread rigidity to prevent buckling without excessively increasing side portion rigidity, thereby preserving steering stability.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The patent uses composite materials by combining the bias structure carcass with an additional reinforcing layer in the radial direction. This composite construction allows the tread portion to have enhanced rigidity for buckling prevention while the overall tire maintains appropriate flexibility for steering.

Inventive Principle:
Principle #40Composite materials

2Strength

If the internal pressure of the tire is increased to suppress deformation of the tread portion, then buckling is prevented, but the outer surface of the tread portion becomes rounded and ground-contact area decreases

Engineering Contradiction:
Improverigidity of tread portionVSAvoidground-contact area
Core Design Contradiction:
StrengthVSArea of stationary object

Solution Approach 1:

The reinforcing layer is positioned specifically in the radial direction at the tread portion, providing localized support against centrifugal forces during turning. This allows the tire to maintain lower internal pressure while still preventing buckling, thereby preserving a flat tread contour and adequate ground-contact area.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The patent addresses the rounding issue by using a reinforcing layer with circumferentially aligned cords that maintain the flat contour of the tread outer surface. This structural approach prevents the tread from rounding even at lower internal pressures, ensuring maximum ground-contact area is maintained.

Inventive Principle:
Principle #14Spheroidality (Curvature)

3Area of stationary object

If a flat contour is employed to increase ground-contact area, then ground-contact area increases, but the tire experiences buckling where tread portion deforms under centrifugal force

Engineering Contradiction:
Improveground-contact areaVSAvoidresistance to centrifugal deformation
Core Design Contradiction:
Area of stationary objectVSStrength

Solution Approach 1:

The patent combines a flat contour tread design with a locally applied reinforcing layer in the radial direction. This allows the tread to maintain a flat contour for maximum ground-contact area while the reinforcing layer provides the necessary resistance to centrifugal forces to prevent buckling during high-speed turning.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The patent creates a composite structure by superimposing a reinforcing layer with radial orientation over the bias structure carcass. This composite construction enables the tire to simultaneously achieve a flat tread contour for increased ground-contact area and sufficient rigidity to resist buckling under centrifugal load.

Inventive Principle:
Principle #40Composite materials

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 design increases turning speed by maintaining high grip force and preventing buckling, while also improving wear resistance and steering stability by distributing ground-contact pressure evenly.

Implementation Method 1

a phenomenon called buckling in which a tread portion is deformed owing to centrifugal force exerted to the vehicle during turning

Methodology Applied
Scientific EffectCentrifugal force: Centrifugal Force

Implementation Method 2

The rigidity of a tread portion of the tire for karts is lower than that of the tire for passenger cars. Consequently, the tire for karts is more likely to experience buckling.

Methodology Applied
Scientific EffectElastic deformation: Elasticity

Data Source

PatentEP4059739B1Tire for karts
Publication Date: 2023.11.29 SUMITOMO RUBBER INDUSTRIES LTD
  • EP4059739B1 patent drawingFigure 1
  • EP4059739B1 patent drawingFigure 2
  • EP4059739B1 patent drawingFigure 3

AI summary

The tire 2 includes: a tread 4 which comes into contact with a road surface; a carcass 10 having a bias structure and located radially inward of the tread 4; and a reinforcing layer 18 located radially inward of the tread 4 and stacked on a radially outer side of the carcass 10. Out of both ends TE of the tread 4, an end TE located on one side in an axial direction is a first end TE1, and an end TE located on another side in the axial direction is a second end TE2. The reinforcing layer 18 is located between an equatorial plane and the first end TE1 of the tread 4. An inner end 38 of the reinforcing layer 18 is located axially inward of a reference ground-contact end PE. The reinforcing layer 18 includes a large number of reinforcing cords 34 aligned in a circumferential direction.