Pneumatic Tire Shoulder Sipes with Deep Shallow Portions
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Solution Overview
Problem
Conventional winter tires deform when contacting icy and snowy roads, leading to stress concentration at the bottom of sipes, which can cause cracking and chunking of tread rubber.
Innovation Solution
A pneumatic tire design featuring a tread portion with a circumferentially extending shoulder main groove, zigzag leading edges, and shoulder sipes that include deep and shallow portions, along with a cap rubber layer of specific hardness, to enhance traction and prevent chunking.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the tread portion uses low hardness rubber to increase ground contacting area, then driving performance on icy and snowy roads is improved, but stress concentration occurs at the bottom of sipes causing cracking and chunking
Solution Approach 1:
The patent applies local quality by creating shoulder blocks with different structural characteristics from other tread blocks. The shoulder blocks have a specific configuration with shoulder sipes at 0-20 degrees angle and a zigzag leading edge, making them more rigid to resist stress concentration and chunking, while the rest of the tread maintains low hardness for good driving performance on ice and snow.
Solution Approach 2:
The shoulder blocks are positioned asymmetrically at the tread edge and have an asymmetric zigzag leading edge design. This asymmetric configuration provides different structural properties at the shoulder area compared to the center tread, allowing the shoulder blocks to better withstand the high stress concentrations that occur at the tread edges during vehicle operation.
2Force
If the tread portion deforms to increase ground contacting area, then friction against the road is improved, but stress concentrates on the bottom of sipes causing cracks
Solution Approach 1:
The shoulder blocks are segmented with multiple shoulder sipes extending from the shoulder main groove toward the tread edge. These sipes divide the shoulder block into multiple segments, which allows controlled deformation and stress distribution. The segmentation prevents stress concentration at any single point while maintaining overall structural integrity during deformation.
Solution Approach 2:
The shoulder sipes are pre-configured at specific angles (0-20 degrees) and depths before the tire contacts the road. This preliminary configuration of the sipe geometry prepares the shoulder blocks to deform in a controlled manner, preventing stress concentration and cracking that would occur with conventional sipe designs.
3Strength
If shoulder blocks are made more rigid to prevent chunking, then chunking resistance is improved, but driving performance on snowy and icy roads may deteriorate
Solution Approach 1:
The patent implements local quality by making only the shoulder blocks (at the tread edge) more rigid through specific geometric configuration, while the rest of the tread blocks maintain low hardness. This localized approach provides chunking resistance where it is most needed (at the high-stress shoulder area) without compromising the overall flexibility and ground contact capability of the tread for good driving performance on snow and ice.
Data Source
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AI summary
A pneumatic tire includes a tread portion (2) with a designated rotational direction (R); the tread portion is provided with a shoulder main groove (3) arranged nearby a tread edge (Te), a plurality of shoulder lateral grooves (4) each extending from the shoulder main groove to the tread edge to form a plurality of shoulder blocks (7); each of the shoulder blocks includes a zigzag leading edge (13) including an external corner with a first vertex (18) formed between a long inclined side and a short inclined side; one of the shoulder blocks is provided with a plurality of shoulder sipes (21) extending at an angle of 0 to 20 degrees with respect to an axial direction of the tire, wherein one of the shoulder sipes includes a deep portion (22) and a shallow portion (23) that is arranged so as to include a position at the same lateral position than the first vertex (18).