Pneumatic Tire Sidewall Projection Design for Pebble Biting Prevention
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Solution Overview
Problem
Conventional pneumatic tires with projections on the groove bottom to prevent pebble biting suffer from reduced rigidity, leading to poor wet performance and increased likelihood of cracks at the projection-root interface.
Innovation Solution
A pneumatic tire design featuring projections on the groove side walls that decrease in height and length as they approach the groove bottom, with an inclined outer surface and arcuate side surfaces, preventing pebble biting while maintaining sufficient groove volume and reducing stress concentrations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If projections are formed on the groove bottom to prevent pebble biting, then pebble biting is suppressed, but the rigidity of the projection is lowered and wet performance deteriorates
Solution Approach 1:
The invention moves the projection from the groove bottom to the groove side wall, changing the spatial dimension where the projection is located. This dimensional shift allows the projection to prevent pebble biting while maintaining groove volume and avoiding the rigidity loss associated with groove bottom projections.
Solution Approach 2:
The projection is designed with varying dimensions along its length, with the cross-sectional area decreasing from the base toward the distal end. This local variation in geometry optimizes the projection's ability to prevent pebble biting at the opening end while controlling stress distribution and maintaining overall structural integrity.
2Reliability
If projection height from groove bottom is increased to prevent pebble biting, then biting prevention improves, but groove volume decreases and wet performance is lowered
Solution Approach 1:
By relocating the projection from the groove bottom to the groove side wall, the invention prevents pebble biting without occupying groove volume. The projection extends from the side wall toward the groove opening, utilizing the lateral space rather than reducing the groove's depth capacity.
3Reliability
If projection is raised steeply from groove bottom, then pebble biting is prevented, but crack occurrence increases at the root portion
Solution Approach 1:
The projection is designed with a curved boundary portion at its base where it joins the groove side wall, replacing a steep angular transition with a gentle curved transition. This curvature eliminates stress concentration at the root portion, preventing crack initiation while maintaining the projection's pebble biting prevention function.
Solution Approach 2:
The projection features a curved boundary portion specifically at the base region where stress concentration would occur, while the upper portion maintains its protective function. This localized curvature modification addresses the crack resistance issue without compromising the overall pebble biting prevention capability.
Data Source
AI summary
Provided is a pneumatic tire where a main groove extending in a tire circumferential direction and a projection projecting toward the inside of the main groove from a groove side wall of the main groove are formed on a tread portion, wherein a projecting amount of the projection from the groove side wall is decreased as the projection extends to a groove bottom of the main groove, the projection terminates at a position outside the groove bottom in a tire radial direction, and a length of the projection along the tire circumferential direction is shortened as the projection extends to a distal end side of the projection in a projecting direction.