Bias Tyre Rubber Boundary Layout for Stable Motorcycle Cornering

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Solution Overview

Problem

Bias tyres for motorcycles suffer from inadequate steering stability during turning due to the use of a single rubber component extending between sidewall portions through the tread portion.

Innovation Solution

The bias tyre design connects tread rubber to sidewall rubber portions to form boundary surfaces, with the outermost ends of these surfaces located on the tyre's outer surface and inward in the radial direction, utilizing different rubber compounds for superior grip and absorption performance to enhance steering stability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If a single rubber component extends between sidewall portions through the tread portion, then the tyre structure is simpler and easier to manufacture, but steering stability during turning deteriorates

Engineering Contradiction:
Improveease of manufactureVSAvoidsteering stability
Core Design Contradiction:
Ease of manufactureVSReliability

Solution Approach 1:

The tyre is segmented into distinct rubber components: tread rubber and sidewall rubber portions. The tread rubber forms a tread portion with a specific tread pattern, while the sidewall rubber portions form sidewalls. These components are positioned adjacently to create boundary surfaces, allowing each segment to be optimized for its specific function - the tread for grip and the sidewalls for structural support and flexibility.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

Different regions of the tyre are assigned different rubber components with locally optimized properties. The tread rubber is designed with specific tread patterns for grip performance, while the sidewall rubber portions are designed for flexibility and structural support. This local differentiation ensures that each part of the tyre has the appropriate material properties for its specific functional requirements, improving overall steering stability.

Inventive Principle:
Principle #3Local quality

2Reliability

If different rubber compounds are used for tread and sidewall portions, then grip performance and absorption performance are improved, but device complexity increases

Engineering Contradiction:
Improvegrip performanceVSAvoiddevice complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The tyre employs composite material construction by combining different rubber compounds for the tread portion and sidewall portions. The tread rubber uses compounds optimized for grip and traction, while the sidewall rubber portions use compounds optimized for flexibility, durability, and absorption of road irregularities. This composite approach allows each material to contribute its superior properties to the overall tyre performance.

Inventive Principle:
Principle #40Composite materials

Solution Approach 2:

The tyre structure is segmented into distinct rubber components that are positioned adjacently. The tread rubber forms the tread portion with tread patterns, while sidewall rubber portions form the sidewalls. By segmenting the tyre into these distinct components, each can be manufactured with optimized rubber compounds for its specific function, and the assembly process becomes a matter of positioning these pre-formed components relative to each other.

Inventive Principle:
Principle #1Segmentation

Data Source

PatentEP4005823B1Bias tyre for two-wheel vehicle
Publication Date: 2023.10.04 SUMITOMO RUBBER INDUSTRIES LTD
  • EP4005823B1 patent drawingFigure 1
  • EP4005823B1 patent drawingFigure 2
  • EP4005823B1 patent drawingFigure 3

AI summary

A bias tyre for two-wheel vehicle includes a tread portion defining a pair of tread edges, a pair of sidewall portions, a carcass having a bias structure, a pair of sidewall rubber portions forming an outer surface of the pair of sidewall portion, and a tread rubber forming an outer surface of the tread portion and connected to the pair of sidewall rubber portions to form a pair of boundary surfaces therebetween, wherein outermost ends in a tyre axial direction of the pair of boundary surfaces are located on an outer surface of the tyre and inwardly in a tyre radial direction of the respective tread edges.