Pneumatic Tire Tread Structure for Wear-Stable Drainage and Low Noise

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Solution Overview

Problem

Existing pneumatic tire designs face decreased drainage performance and pattern noise issues due to wear progression, as groove volume decreases and widthwise sipes can contribute to noise.

Innovation Solution

The tire features circumferential main grooves with widthwise grooves and sipes, including a widened portion on the sipe bottom, inclined at specific angles to maintain drainage and reduce noise, with a rectangle ratio of 0.8 or more in the contact patch, ensuring effective water evacuation and noise suppression.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If widthwise grooves are provided in the widthwise outermost land portion to improve drainage performance, then drainage performance is improved, but groove volume decreases when wear progresses

Engineering Contradiction:
Improvedrainage performanceVSAvoidservice life
Core Design Contradiction:
ReliabilityVSDuration of action of moving object

Solution Approach 1:

The patent implements nested drainage structures by placing widthwise sipes inside the widthwise grooves. The sipes are positioned within the groove boundaries and extend in the tire circumferential direction, creating a hierarchical drainage system where sipes are nested within grooves. This nested configuration ensures that even when groove volume decreases due to wear, the nested sipes continue to provide drainage functionality, thereby maintaining drainage performance throughout the tire's service life.

Inventive Principle:
Principle #7Nested doll (Nesting)

2Reliability

If widthwise sipes are provided in the widthwise outermost land portion to remove water film and improve drainage, then drainage performance is improved, but pattern noise increases

Engineering Contradiction:
Improvedrainage performanceVSAvoidpattern noise
Core Design Contradiction:
ReliabilityVSObject-generated harmful factors

Solution Approach 1:

The patent applies local quality by creating a widened portion at the bottom of the widthwise sipes that extends in the tire radial direction. This localized structural modification changes the sipe geometry from a uniform cross-section to a variable cross-section with a widened bottom portion. The widened bottom portion alters the local acoustic characteristics and water flow dynamics, reducing pattern noise generation while maintaining the water film removal capability and drainage performance of the sipes.

Inventive Principle:
Principle #3Local quality

3Reliability

If groove volume is maintained to preserve drainage performance, then drainage performance is maintained, but device complexity increases

Engineering Contradiction:
Improvedrainage performanceVSAvoidtread structure complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent segments the drainage function into two distinct components: widthwise grooves extending in the tire width direction and widthwise sipes extending in the tire circumferential direction. The sipes are positioned within the grooves and have different orientation and functional characteristics. This segmentation allows each component to perform its specific drainage function efficiently, maintaining overall drainage performance while using simple, well-defined geometric shapes that are easy to manufacture and analyze.

Inventive Principle:
Principle #1Segmentation

Data Source

PatentEP4046825B1Pneumatic tire
Publication Date: 2024.06.05 BRIDGESTONE CORP
  • EP4046825B1 patent drawingFigure 1
  • EP4046825B1 patent drawingFigure 2
  • EP4046825B1 patent drawingFigure 3A~3B

AI summary

A pneumatic tire includes circumferential main grooves extending in the tire circumferential direction on the tread surface, and in widthwise outermost land portions, widthwise grooves extending from the tread edges inward in the tire width direction and widthwise sipes extending from the tire widthwise inner edge of the widthwise grooves inward in the tire width direction and connecting to the circumferential main groove. Each widthwise sipe includes a widened portion, by the sipe bottom, with a larger sipe width than at the tread surface. A rectangle ratio is 0.8 or more. Each widthwise sipe extends at a first angle relative to the tire width direction in plan view of the tread surface. In a tire radial region containing the widened portion, the widened portion extends at a second angle smaller than the first angle relative to the tire width direction, or partially extends along the tire width direction.