Tire Block Dent Structure for Stress Distribution

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Solution Overview

Problem

Pneumatic tires for off-road vehicles face durability issues due to repeated stress and potential chunking when used on rough terrain, compromising traction, braking, and cornering performance.

Innovation Solution

A pneumatic tire with a tread pattern featuring blocks of specific design, including a polygonal top face, radially inward slant surfaces with intersecting planes, and a star-polygonal cross-section, optimized for a land ratio of 8-30% and block height of 10-19mm, enhancing rigidity and traction while reducing stress concentrations.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If blocks are arranged sparsely with low land ratio to obtain traction on rough terrain, then traction and cornering performance is improved, but block durability deteriorates due to repeated large stress

Engineering Contradiction:
Improvetraction performanceVSAvoidblock durability
Core Design Contradiction:
ReliabilityVSStrength

Solution Approach 1:

The patent applies local quality by creating a dent structure at specific locations on the block (at the slant surface) while maintaining the overall block integrity. This localized structural modification allows the block to have different mechanical properties in different regions: the dent area absorbs and distributes stress, while the rest of the block maintains its strength for traction. This resolves the contradiction by enabling the block to withstand repeated stress without compromising the sparse arrangement needed for rough terrain traction.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The dent structure acts as a pre-designed stress absorption zone that cushions the block against repeated impacts before damage occurs. By incorporating this cushioning feature in advance during tire manufacturing, the block is prepared to handle the large stresses of rough terrain operation, preventing cracks and chunking while maintaining the low land ratio configuration for optimal traction.

Inventive Principle:
Principle #11Beforehand cushioning (Prior cushioning)

2Reliability

If block height is increased to improve traction engagement, then traction performance is improved, but stress concentration increases leading to cracks and chunking

Engineering Contradiction:
Improvetraction engagementVSAvoidstress concentration
Core Design Contradiction:
ReliabilityVSStress or pressure

Solution Approach 1:

The dent structure creates a localized region with different mechanical characteristics that specifically addresses stress concentration issues. By positioning the dent at the slant surface of the block, the design allows stress to be redistributed in a controlled manner, preventing the concentration of forces that would otherwise lead to cracks and chunking in high-block-height configurations.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The invention introduces a dimensional feature (the dent) on the block surface that adds a new geometric element to the block structure. This third-dimensional modification to the block geometry allows for stress distribution without requiring changes to the block height, thereby maintaining traction engagement while eliminating stress concentration problems.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

3Strength

If land ratio is increased to improve durability, then block durability is improved, but traction and cornering performance deteriorates due to reduced engagement with rough terrain

Engineering Contradiction:
Improveblock durabilityVSAvoidtraction performance
Core Design Contradiction:
StrengthVSReliability

Solution Approach 1:

The dent structure provides a localized durability enhancement that allows the overall land ratio to remain low. By concentrating the durability-improving feature (the dent) at critical stress points on the blocks, the design achieves enhanced block durability without needing to increase the overall land ratio, thus maintaining optimal traction performance on rough terrain.

Inventive Principle:
Principle #3Local quality

Data Source

PatentEP2664465B1Pneumatic tire for running on rough terrain
Publication Date: 2017.02.22 SUMITOMO RUBBER INDUSTRIES LTD
  • EP2664465B1 patent drawing
  • EP2664465B1 patent drawing
  • EP2664465B1 patent drawing

AI summary

A pneumatic tire for rough terrain comprises a tread portion with a tread pattern provided with a block having a height of from 10 to 19 mm, the block comprising a top face and a sidewall face extending radially inwardly from a peripheral edge of the top face, the top face being a polygonal shape with a plurality of sides equal to or more than four, the sidewall face comprising a plurality of slant surfaces extending radially inwardly away from the sides, respectively, wherein each slant surface comprises a radially outer portion and a radially inner portion, the radially outer portion has a flat plane, the radially inner portion comprises a first plane and a second plane laterally adjacent to said first plane, and the first plane and second plane cross each other so that said radially inner portion dents inwardly of the block.