Winter Tire Sipe Geometry for Snow Traction and Braking
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Solution Overview
Problem
Existing winter tires struggle to provide maximum traction and optimal braking on snow-covered surfaces while maintaining ease and cost-effectiveness in manufacturing.
Innovation Solution
The tire design incorporates sipes with non-constant thickness and complementary surfaces along the radial direction, optimized by varying the shift and geometry of the sipe surfaces to enhance interlocking and rigidity during loading, thereby improving traction and braking performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If sipes with constant cross-section are used, then the manufacturing process is simple, but the traction and braking performance on snow-covered surfaces is insufficient
Solution Approach 1:
The sipe geometry is designed with non-constant cross-section, where the thickness varies along the radial direction. Specifically, the sipe has a first thickness at the tread surface and a second, greater thickness at the bottom, creating localized thickness variations that enhance snow interlocking capability while maintaining manufacturing feasibility through mold design
Solution Approach 2:
The sipe incorporates asymmetric features including inclined surfaces that are not parallel to each other, and complementary shapes on opposing walls. The sipe includes projections on one wall that correspond to depressions on the opposite wall, creating an asymmetric geometry that improves mechanical interlocking with snow particles during traction and braking operations
2Reliability
If numerous sipes are provided to increase snow interlocking, then traction on snow improves, but the structural rigidity of tread portions decreases
Solution Approach 1:
The sipe thickness is varied locally along its length, being thinner at the surface for flexibility and snow contact, and thicker at the base for structural support. This localized thickness variation allows the sipe to provide enhanced snow interlocking at the contact surface while the thicker base portion maintains the overall rigidity and structural integrity of the tread block
Solution Approach 2:
The sipe geometry is pre-designed with complementary shapes and projections that are intended to interlock with snow particles before actual contact occurs. The inclined surfaces and protrusions are shaped in advance to maximize mechanical engagement with the snowpack, allowing the tread to effectively 'grip' snow particles upon contact
Data Source
Figure 1
Figure 2~3
Figure 4
AI summary
Pneumatic tyre (1) with an annular tread (7) having a plurality of tread portions (18, 21) which define an upper surface (13) for sliding over the road surface and are delimited by a plurality of grooves (15); and a number of sipes (20) defined by slots formed within the tread portions (18, 21); and provided with a first surface (22, 25) having at least a first curved section (22B, 25B) with a maximum point (P, R) and a second surface (23, 26) having at least a second curved section (23B, 26B), facing the first section (22B, 25B) and having a minimum point (P* R*); wherein the distance (ΔP) along the radial direction between the minimum point (P* R*) and the maximum point (P, R) is non-zero.