Main Tread Groove Geometry for Tire Stone-Biting Prevention
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Solution Overview
Problem
Heavy-duty pneumatic tires face issues with stone biting and tread separation when running on non-paved roads, leading to reduced performance and potential complications in tire design due to the need for complex shapes to prevent stone biting.
Innovation Solution
The pneumatic tire design features a circumferential main groove with specific geometric parameters, including cross-sectional area ratios, groove widths, and zigzag shapes, which prevent stone biting without requiring a complicated shape, thereby enhancing durability and performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a projection is partially provided on a groove bottom or groove wall to prevent stone biting, then stone biting is prevented, but the shape becomes complicated causing vulcanization failures and molding difficulties
Solution Approach 1:
The patent applies parameter changes by optimizing the groove cross-sectional area ratio (SD/SU between 0.15 and 0.60) and groove width ratio (W1/W between 0.60 and 0.78) to prevent stone biting without adding complex projections. This resolves the contradiction by achieving reliability improvement through parameter optimization rather than structural complexity.
Solution Approach 2:
The patent introduces asymmetry by creating an inflection portion on the groove wall where the groove wall angle changes from the groove opening edge toward the groove bottom. This asymmetric feature prevents stone biting while maintaining a relatively simple overall groove shape, avoiding the complexity of symmetric projections.
2Reliability
If the groove width is reduced at the lower portion to prevent stone biting, then stone biting is prevented, but the groove shape becomes complicated
Solution Approach 1:
The patent uses parameter changes by defining specific ratio ranges for cross-sectional areas (SD/SU between 0.15 and 0.60) and groove widths (W1/W between 0.60 and 0.78). These parameter optimizations achieve stone biting prevention while maintaining simple groove shapes that are easy to mold and vulcanize.
Solution Approach 2:
The patent transitions from two-dimensional groove width reduction to three-dimensional cross-sectional area control by introducing the inflection portion and defining area ratios. This dimensional approach prevents stone biting through volumetric control rather than simple width reduction, maintaining shape simplicity.
3Reliability
If a shelf step is provided in the groove to narrow the groove width, then braking performance and steering stability are improved, but the groove shape becomes more complex
Solution Approach 1:
The patent applies parameter changes by optimizing the groove wall angle (not less than 10° and not greater than 45°) and the position of the inflection portion (height HT from groove bottom satisfying 0.1≤HT/D≤0.5). These parameter optimizations achieve improved braking and steering performance without the complexity of shelf steps.
Solution Approach 2:
The patent inverts the conventional approach by instead of adding shelf steps to narrow the groove, it controls the groove wall angle and creates an inflection portion that naturally tapers the groove. This inverted approach achieves similar performance benefits with simpler structure.
Data Source
AI summary
A pneumatic tire includes a circumferential main groove extending in a tire circumferential direction in a tread surface of a tread portion, wherein when the circumferential main groove is segmented into an outer side in a tire radial direction and an inner side in the tire radial direction by drawing an imaginary segment line parallel with a straight line connecting each of groove opening edges at a position of ½ of a groove depth in a meridian cross-section, a cross-sectional area SU on the outer side in the tire radial direction and a cross-sectional area SD on the inner side in the tire radial direction satisfy the relationship 0.15≤SD/SU≤0.60.