Alternating Open and Closed Sipes for Tire Durability
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Solution Overview
Problem
Existing pneumatic tires face a trade-off between maintaining high on-ice performance and durability, as increasing the number of sipes to enhance on-ice performance leads to reduced block rigidity and increased stress concentration, resulting in cracks, while measures to enhance durability often compromise on-ice performance.
Innovation Solution
A pneumatic tire design featuring alternating open and closed sipes in the circumferential direction, with the depth of open sipes offset to be shallower than closed sipes, and a double-layer rubber composition with a harder lower layer, where sipes extend into the lower layer portion, to disperse stress and maintain block rigidity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the number of sipes is increased to enhance on-ice performance, then the on-ice performance is improved, but the block rigidity is lowered and stress concentration increases, resulting in reduced durability
Solution Approach 1:
The sipes are segmented into two types: open sipes that extend from the tread surface to the lower layer portion, and closed sipes that extend only to the intermediate layer portion. This segmentation allows each type to perform different functions - open sipes provide biting edges for on-ice performance while closed sipes maintain block rigidity and reduce stress concentration at the bottom portions.
Solution Approach 2:
Different regions of the block are given different sipe characteristics. The open sipes are positioned to provide edge effect where needed for ice grip, while closed sipes are positioned to maintain structural integrity. This local differentiation allows the block to simultaneously achieve high on-ice performance and maintain sufficient rigidity.
2Reliability
If crossing sipes are added to enhance durability, then some durability improvement is achieved, but the blocks become smaller and the durability enhancement effect is insufficient
Solution Approach 1:
Instead of adding crossing sipes that would fragment the blocks further, the invention segments the sipes in the width direction into open and closed types. This allows durability to be improved through selective sipe termination without reducing the overall block size and maintaining the necessary structural integrity.
3Reliability
If blocks of different heights are formed to offset sipe depths, then some durability improvement is achieved, but blocks with larger height have higher contact pressure and are more worn
Solution Approach 1:
Instead of creating blocks of different heights which would lead to uneven wear, the invention applies local quality by having different sipe depths (open vs closed) within blocks of uniform height. This allows the stress distribution and durability characteristics to be optimized locally through sipe configuration rather than through varying block dimensions, preventing concentrated wear on specific blocks.
Data Source
AI summary
A pneumatic tire has a tread surface for simultaneously achieving both enhanced on-ice performance and enhanced durability. The pneumatic tire includes sipes extending in the width direction of the tire that are arranged at intervals in the circumferential direction of the tire at least in shoulder blocks that are divided by longitudinal grooves extending in the circumferential direction of the tire and by lateral grooves extending in the width direction of the tire. Open sipes and closed sipes are alternately arranged, and the depth of the open sipes is less than the depth of the closed sipes.