Pneumatic Tire Rim Protector Contour and Side Apex Stiffness
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Solution Overview
Problem
Pneumatic tires face challenges in maintaining stiffness while minimizing weight, particularly with rim protectors that need to function effectively across various rim sizes without increasing tire weight or interfering with the flange during mounting.
Innovation Solution
The design incorporates a rim protector with a specific contour represented by two circular arcs, ensuring effective prevention of sidewall and flange damage, and a side apex that enhances in-plane torsional stiffness without significant weight increase, using a bob profile and appropriate positioning to maintain functionality across 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 weight of the tire is reduced, but the stiffness of the tire deteriorates
Solution Approach 1:
The side piece is divided into functionally distinct regions: the main body (sidewall) and the rim protector. This segmentation allows the main body to be minimized for weight reduction while the rim protector is optimized specifically for stiffness and protective function, resolving the contradiction between overall weight reduction and localized stiffness requirements
Solution Approach 2:
The rim protector is designed with specific local geometric characteristics (circular arc contours with defined radii and positioning) to concentrate stiffness where needed for rim protection and tire stability, while the rest of the tire structure can be minimized for weight reduction. This localized quality enhancement addresses stiffness requirements without compromising overall weight reduction goals
2Reliability
If the size of the rim protector is increased to prevent damage of sidewall or flange, then the protective function is improved, but the weight of the tire increases
Solution Approach 1:
The rim protector's dimensions are precisely controlled through specific parameter ranges: the first radius R1 (150-450mm), second radius R2 (15-40mm), and positioning parameters (h3/H ratio of 0.29-0.41). These parameter optimizations ensure the rim protector provides sufficient protective function while minimizing material usage and weight increase
3Adaptability or versatility
If the rim protector is designed to fit all applicable rims, then the adaptability is improved, but the design complexity increases
Solution Approach 1:
The rim protector is designed as a universal component that can be applied across multiple rim sizes within a standard tire specification range. The geometric parameters (R1, R2, h3/H ratio) are optimized to provide consistent protective function whether the tire is mounted on the largest or smallest applicable rim, eliminating the need for rim-specific protector variations and simplifying the overall design
Data Source
AI summary
Each side piece 40 of a tire 2 includes a rim protector 42. A bob profile representing a contour of the rim protector 42 includes a first circular arc extending outward from a top PT of the rim protector 42, and a second circular arc extending inward from the top PT. A center of the first circular arc is located inward of the bob profile, and a center of the second circular arc is located outward of the bob profile. The side piece 40 includes a side apex 22, and the side apex 22 intersects a normal line LT that is normal to a carcass 12 and passes through the top PT.