Pneumatic Tire Rim Protector Geometry for Stiffness and Weight
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Solution Overview
Problem
Pneumatic tires face challenges in maintaining stiffness while minimizing weight, especially when equipped with rim protectors that need to function effectively across various rim sizes without increasing rolling resistance or interfering with the tire's mounting.
Innovation Solution
The design incorporates a rim protector with specific geometric features, including inclined surfaces and circular arcs, that project outward and inward radially, optimizing its height, thickness, and curvature to enhance stiffness while maintaining a low weight and preventing damage from curbs, and ensuring proper mounting on different rim sizes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of moving object
If the volume of components such as sidewalls is reduced to decrease tire weight, then the tire weight is reduced, but the stiffness of the tire deteriorates
Solution Approach 1:
The tire is divided into functional segments: the rim protector segment (protruding portion) provides stiffness and protection, while the reduced-volume sidewall segment minimizes weight. This segmentation allows each part to optimize its volume for its specific function without compromising overall performance.
Solution Approach 2:
The rim protector is designed with specific local geometric qualities (protrusion height of 5-15mm, specific cross-sectional shape) concentrated at the bead area where it is most needed for stiffness and curb protection, while the rest of the tire structure maintains reduced volume for weight savings.
2Stability of the object's composition
If the size of the rim protector is increased to enhance stiffness and curb protection, then the stiffness is improved, but the tire weight increases
Solution Approach 1:
Instead of increasing the overall tire structure, only the necessary minimal protrusion (5-15mm) is added at the rim protector location to achieve the required stiffness and protection level, avoiding excessive weight gain while providing sufficient functional improvement.
3Adaptability or versatility
If the rim protector is designed to function with all applicable rim sizes, then the adaptability is improved, but the device complexity increases due to size adjustment requirements
Solution Approach 1:
The rim protector is designed with universal geometric parameters (protrusion height ratio of 5-15mm relative to tire cross-section, specific cross-sectional dimensions) that allow it to function effectively across multiple rim size specifications without requiring different designs or adjustments for each rim type.
4Reliability
If the rim protector projects outward more to prevent curb contact, then the protection function is improved, but the rolling resistance increases
Solution Approach 1:
The rim protector parameters (protrusion height of 5-15mm, cross-sectional dimensions) are optimized to achieve the minimum effective protection level that prevents curb contact damage while maintaining a profile that minimizes contact with the road surface during rolling, thereby balancing protection function with acceptable rolling resistance.
Data Source
AI summary
A rim protector 40 of a tire 2 projects from a reference surface 44 of each side piece 38. The rim protector 40 has a first inclined surface 50 and a second inclined surface 52. A profile of the reference surface 44 includes an outer circular arc and an inner circular arc which are tangent to each other at a reference position. A first circular arc of the first inclined surface 50 is tangent to the outer circular arc, and a second circular arc of the second inclined surface 52 is tangent to the inner circular arc. A ratio of a height H relative to a cross-sectional height SH is equal to or greater than 0.27 and equal to or less than 0.34. A projecting length W is equal to or greater than 12 mm and equal to or less than 18 mm.