Tyre Block Corner Design for Wet Traction

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Solution Overview

Problem

Conventional tires experience reduced frictional force and braking ability due to block deformation under tangential stresses, leading to partial block rising and reduced contact area, which affects traction and stability, especially on wet roads.

Innovation Solution

The tire design incorporates a connection surface between the lateral wall and tread surface that forms a corner, allowing for controlled deformation and maintaining a constant contact area, reducing localized overpressures and improving water evacuation, thereby enhancing traction and stability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Force

If the blocks are subjected to tangential stress during braking, then the front edge generates overpressure to press the block against the road surface, but the rear edge generates pressure decrease causing the block to rise and reduce contact area

Engineering Contradiction:
Improvefrictional forceVSAvoidcontact area stability
Core Design Contradiction:
ForceVSStability of the object's composition

Solution Approach 1:

The patent applies preliminary action by providing a chamfer (inclined plane) at the rear edge of the block before braking occurs. This pre-configured geometric feature prepares the block to gradually reduce the pressure decrease and prevent excessive rising during braking, thereby maintaining more stable contact area throughout the braking process.

Inventive Principle:
Principle #10Preliminary action

2Stability of the object's composition

If wide and deep chamfers are provided to maintain contact area, then block rising is reduced, but the contact surface size and block rigidity are excessively reduced

Engineering Contradiction:
Improvecontact area stabilityVSAvoidblock rigidity
Core Design Contradiction:
Stability of the object's compositionVSStrength

Solution Approach 1:

The patent applies parameter changes by precisely controlling the chamfer dimensions within specific ranges: the chamfer angle is limited to 5°-15° and the chamfer length to 0.5-2mm. These optimized parameters allow the chamfer to sufficiently prevent block rising and maintain contact area stability, while avoiding excessive reduction in contact surface size and block rigidity that would occur with wider and deeper chamfers.

Inventive Principle:
Principle #35Parameter changes

3Stability of the object's composition

If the lateral wall and tread surface are connected by an inclined plane chamfer, then block deformation is controlled, but the contact surface area is reduced and noise increases

Engineering Contradiction:
Improveblock shape stabilityVSAvoidnoise
Core Design Contradiction:
Stability of the object's compositionVSObject-generated harmful factors

Solution Approach 1:

The patent applies parameter changes by optimizing the chamfer geometry with specific angle (5°-15°) and length (0.5-2mm) parameters. This controlled chamfer design sufficiently manages block deformation during braking while minimizing the contact surface reduction and noise generation that would occur with more aggressive chamfer configurations.

Inventive Principle:
Principle #35Parameter changes

Data Source

PatentEP3638517B1Tyre for vehicle wheels
Publication Date: 2021.05.12 PIRELLI TYRE SPA
  • EP3638517B1 patent drawingFigure 1~4
  • EP3638517B1 patent drawingFigure 5~6
  • EP3638517B1 patent drawingFigure 7~10

AI summary

A tyre (1) for vehicle wheels, comprising a tread band (2) on which a radially external tread surface (3) and a plurality of recesses (9; 9a) that delimit a plurality of blocks (10, 10a; 100; 200; 300) are defined;each block comprises a tread surface portion (11) and a first lateral wall (12) that extends, at least in part, from a bottom (13) of one of the recesses towards the tread surface portion and is connected, at least for a section thereof, to the tread surface portion (11) by a connection surface (15) having an at least partially curvilinear profile; the connection surface (15) is joined to the first lateral wall along a contact line, at which the tangent plane of the first lateral wall and the tangent plane of the connection surface form an acute angle (a) of more than 20° such that a corner is defined between the connection surface (15) and the first lateral wall (12); furthermore, the connection surface (15) is joined to the tread surface (11) along a contact line in a substantially tangential manner.