Nonpneumatic Tire Shear Hoop Structure for Rounded Contact Patch
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Solution Overview
Problem
Prior art nonpneumatic tires with uniform spoke stiffness and diameter buckle upon contact, leading to a contact patch with straight edges, which results in poor ride harshness, increased soil compaction, and vibration.
Innovation Solution
The design incorporates multiple spoke rings with varying stiffness and diameter, along with high annular strength shear hoops, to create a rounded contact patch shape, optimizing footprint behavior and traction mobility by distributing load effectively across the tire.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If uniform spoke rings with same stiffness and diameter are used, then the structure is simple and easy to manufacture, but the spokes buckle upon contact creating straight-edged contact patch leading to poor ride comfort and increased vibration
Solution Approach 1:
The patent applies local quality by varying the stiffness and diameter of different spoke rings according to their axial positions. Spoke rings have different outer diameters and stiffness values, with intermediate spoke rings having different properties than outer or inner spoke rings. This non-uniform configuration allows each spoke ring to perform optimally for its specific location, preventing buckling and creating a rounded contact patch while maintaining manufacturability through systematic variation rather than complex random design.
2Device complexity
If uniform spoke rings are used, then the device complexity is low, but the load distribution is poor causing straight contact patch edges and soil compaction
Solution Approach 1:
The patent implements parameter changes by systematically varying the outer diameter and stiffness parameters of spoke rings along the axial direction. Each spoke ring has specifically designed parameters (different outer diameters D1, D2, D3 and corresponding stiffness values) that change progressively from outer to inner rings. This parameter variation optimizes load distribution across the contact patch, creating curved edges that reduce soil compaction while keeping the overall device structure relatively simple and systematic.
3Strength
If the web or spokes are made of material stronger in tension than compression, then the load can be distributed through remaining portions when buckling occurs, but this creates asymmetry in material properties that may affect overall performance
Solution Approach 1:
The patent applies preliminary anti-action by designing the non-uniform spoke ring configuration to prevent buckling from occurring in the first place. Rather than relying on material asymmetry to distribute load after buckling occurs, the varying stiffness and diameter of spoke rings create a structure that resists buckling through its geometric and mechanical design. The intermediate spoke rings with optimized parameters act in advance to maintain structural integrity and prevent the harmful buckling-deflection-buckling cycle.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution enhances ride comfort, reduces soil compaction, and minimizes vibrations by creating a rounded contact patch with curved edges, allowing for better load distribution and improved traction.
Implementation Method 1
Each shear hoop includes an elastic central region sandwiched between two inelastic outer regions
Implementation Method 2
Each shear hoop includes an elastic central region sandwiched between two inelastic outer regions
Data Source
Figure 1~2
Figure 3~4
Figure 5
AI summary
A nonpneumatic tire includes an annular outer surface, an annular inner surface, and a webbing extending from the annular outer surface to the annular inner surface. The nonpneumatic tire also includes a plurality of shear elements extending circumferentially around the annular outer surface and spaced laterally apart from each other. Each shear element includes a substantially inelastic lower region, a substantially inelastic upper region, and an elastic region disposed between the substantially inelastic lower region and the substantially inelastic upper region. The nonpneumatic tire further includes a tread layer extending circumferentially around the plurality of shear elements.