Pre-stressed Toroidal Element Tire for Unpressurized Run-flat Operation

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Solution Overview

Problem

Conventional tires lack the ability to maintain structural integrity and support load without internal air pressure, and existing run-flat tires often rely on stiffness alone, leading to uneven contact pressure and propensity to buckle when deflated.

Innovation Solution

A tire design featuring a toroidal element with a central elastic region and outer inextensible regions, pre-stressed to exert outward forces on the rim flanges, allowing it to maintain a contact patch similar to a pneumatic tire even when unpressurized, by using a combination of body ply layers and inner rubber components.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a tire uses a thin annular high strength band element to maintain structural integrity when unpressurized, then the tire can operate without internal air pressure, but the contact pressure becomes uneven and the tire is prone to buckling

Engineering Contradiction:

Improvestructural integrity when unpressurizedVSAvoiduniformity of contact pressure

Core Design Contradiction:

ReliabilityVSStability of the object's composition

Solution Approach 1:

The toroidal element incorporates an elastic central region between inextensible body ply layers, creating local quality differentiation. The central region allows controlled deformation and pressure distribution, while the body plies maintain overall structural integrity, preventing buckling and ensuring uniform contact pressure across the tire footprint.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The tire combines different material properties within the toroidal element - elastic central region material versus inextensible body ply material - to achieve both structural support and uniform pressure distribution. This composite structure allows the tire to maintain reliability when unpressurized while avoiding the buckling and uneven contact pressure problems of homogeneous designs.

Inventive Principle:

Principle #40Composite materials

2Shape

If a tire is designed to run unpressurized using rigid structural elements, then it can maintain shape without air pressure, but it loses the ability to provide a large uniform contact area with lower contact pressure

Engineering Contradiction:

Improvemaintenance of tire shape without air pressureVSAvoidcontact area with ground

Core Design Contradiction:

ShapeVSArea of stationary object

Solution Approach 1:

The toroidal element's central region is designed with elastic properties that allow it to deform and conform to the ground surface, increasing the contact area. Meanwhile, the pre-stressed body plies maintain the overall tire shape and prevent collapse, achieving both large contact area and shape maintenance without requiring internal air pressure.

Inventive Principle:

Principle #35Parameter changes

3Reliability

If a tire uses pre-stressed toroidal element with elastic central region, then it maintains large uniform contact area with lower contact pressure, but the structure becomes more complex than conventional run-flat tires

Engineering Contradiction:

Improvecontact pressure distributionVSAvoidtoroidal element structure

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The elastic central region is nested between the inextensible body ply layers within the toroidal element structure. This nested configuration allows the complex multi-functional structure to be integrated efficiently, with the central region providing pressure distribution while the body plies provide structural support, all within a compact toroidal form factor.

Inventive Principle:

Principle #7Nested doll (Nesting)

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 toroidal element design provides a large, uniform contact area with lower contact pressure and reduced buckling, similar to a pneumatic tire, while eliminating the need for internal air pressure and enhancing durability.

Implementation Method 1

At least a portion of the central region is more elastic than the inner and outer regions

Methodology Applied

Scientific EffectElasticity: Elasticity

Implementation Method 2

The toroidal element is pre-stressed such that the first sidewall portion of the toroidal element exerts a first axially outward force, and such that the second sidewall portion of the toroidal element exerts a second axially outward force

Methodology Applied

Scientific EffectPre-stress:

Data Source

PatentEP3129242B1Tire with pre-stressed toroidal element

Publication Date: 2019.07.24 BRIDGESTONE AMERICAS TIRE OPERATIONS LLC

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AI summary

A tire includes at least one body defining a plurality of body ply layers, and a toroidal element located between the body ply layers. The toroidal element includes inner and outer regions formed by the body ply layers, and a central region formed by an inner rubber component located between the body ply layers. At least a portion of the central region is more elastic than the inner and outer regions. The toroidal element includes a first sidewall portion extending along at least a portion of the first sidewall region of the tire, and a second sidewall portion extending along at least a portion of the second sidewall region of the tire. The toroidal element is pre-stressed such that the first sidewall portion of the toroidal element exerts a first axially outward force, and such that the second sidewall portion of the toroidal element exerts a second axially outward force.