EVA Tire Insert Geometry for Run-Flat Support Without Tire Rubbing
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Solution Overview
Problem
Existing tire inserts for off-road vehicles and normal road vehicles are not reliable over time, as they wear out quickly due to heat and internal rubbing, and they compromise tire dynamics and performance by being in contact with the tire.
Innovation Solution
A tire insert made of expanded polymeric material, specifically ethylene vinyl acetate (EVA), with a unique shape and size that allows it to be spaced apart from the tire when inflated, but comes into contact with the tire when deflated or under pressure drop to support it, thus minimizing interference with tire performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the insert is made to contact the inner wall of the tire to provide support, then tire support reliability is improved, but tire dynamic performance deteriorates due to biasing effects
Solution Approach 1:
The insert is designed with a compliant, deformable structure that dynamically adapts its contact with the tire based on operating conditions. During normal inflation, the insert deforms to remain spaced from the tire, eliminating biasing effects. During deflation or puncture, the insert deforms to contact and support the tire, providing reliability when needed.
Solution Approach 2:
The insert utilizes changes in physical parameters (deformation, spacing) based on tire pressure conditions. When tire pressure is normal, the insert maintains a spaced configuration. When tire pressure drops, the insert deforms to contact the tire, changing its physical state to provide support without requiring active control.
2Reliability
If the insert completely fills the tire to replace air support, then puncture protection is improved, but tire wear increases due to internal rubbing and heat
Solution Approach 1:
The insert is designed to provide partial support rather than complete tire filling. It occupies only the necessary volume to provide puncture protection and support during deflation, leaving space for air to continue providing primary support during normal operation. This reduces internal rubbing and heat generation while maintaining puncture protection capability.
Solution Approach 2:
The invention extracts the essential support function from the insert, allowing it to provide puncture protection without completely filling the tire. The insert is removed from continuous contact with the tire during normal operation, reducing wear from internal rubbing and heat while maintaining reliability during puncture events.
3Reliability
If the insert is designed to contact the tire for support, then support during puncture is improved, but tire performance homogeneity deteriorates under various working positions
Solution Approach 1:
The insert employs a dynamic, compliant structure that automatically adjusts its position and contact with the tire based on vehicle orientation and terrain. During normal operation, it remains spaced from the tire regardless of working position. During puncture, it deforms to contact and support the tire, providing reliable support without compromising performance homogeneity under various conditions.
Data Source
Figure 1~3
Figure 4
AI summary
A tire insert (1) for vehicle wheel (2) comprises an annular element (10) made in one piece and of polymer material. The tire insert (1) is characterized in that said annular element (10) comprises a base portion (11), suitable for being accommodated in a rim seat (51) of the wheel rim (5) and an enlarged portion (12), having a section larger than the base portion (11). In particular, the enlarged portion (12) is shaped to have shape and size to be always spaced apart from the inner tire side (41) when the tire is inflated to a predetermined standard working pressure of the tire. When, on the other hand, the tire is deflated, the enlarged portion (12) comes into contact with the tire to support it while the wheel is running. A vehicle wheel (2) comprises a tire (4), a rim (5) onto which the tire (4) is mounted, and the tire insert (1).