Carbon Bicycle Frame with Variable Wall Thickness
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Solution Overview
Problem
Classical bicycles made of metallic circular pipes are heavy and lack the strength to handle torsion stress effectively, while modern bicycles using carbon materials are lighter but require thicker tubes for strength, deviating from traditional designs.
Innovation Solution
A carbon material body frame for bicycles with tubes designed to have varying thicknesses, mimicking the traditional circular pipe shape, where thicker sections are strategically placed to manage torsion stress and maintain a classic appearance, using epoxy resin with aramid fibers for added reinforcement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Shape
If metallic circular pipes are used for the body frame, then the traditional appearance is maintained, but the weight increases and torsion stress resistance decreases
Solution Approach 1:
The patent applies composite materials by combining carbon fiber with epoxy resin to create a body frame that maintains the traditional circular pipe appearance while significantly reducing weight. The carbon fiber reinforced plastic composite provides both the aesthetic circular shape and the structural performance needed, resolving the contradiction between traditional appearance and weight reduction.
Solution Approach 2:
The patent implements local quality by varying the wall thickness of the carbon fiber tubes at different locations. Thicker sections are placed where torsion stress is highest (such as near the bottom bracket and head tube), while thinner sections are used where less stress is expected. This localized thickness variation maintains the traditional circular appearance while optimizing weight and strength distribution.
2Weight of moving object
If carbon material is used for the body frame, then the weight is reduced, but the tube thickness must be increased to maintain strength
Solution Approach 1:
The patent resolves this contradiction by applying local quality through non-uniform wall thickness distribution in the carbon fiber tubes. The tubes have thicker walls at critical stress points (bottom bracket area, head tube connection) and thinner walls elsewhere, allowing the use of carbon material to reduce overall weight while maintaining sufficient strength through strategic thickness placement rather than uniform thickening.
Solution Approach 2:
The use of carbon fiber reinforced plastic composite material enables weight reduction while maintaining strength without requiring uniformly thick tubes. The high strength-to-weight ratio of carbon composite allows for thinner overall tube walls compared to traditional metals, with localized thickness increases only where structurally necessary.
3Ease of manufacture
If uniform tube thickness is used in carbon material frames, then manufacturing is simplified, but torsion stress resistance is insufficient
Solution Approach 1:
The patent addresses this contradiction by implementing local quality through variable wall thickness in the carbon fiber tubes. By placing thicker sections at locations experiencing highest torsion stress (such as the bottom bracket area and head tube connections) and thinner sections elsewhere, the design achieves optimal strength distribution while remaining manufacturable through molded carbon fiber reinforcement techniques.
Data Source
AI summary
Disclosed herein is a body frame for a bicycle which is able to provide higher strength in such a way to use a carbon material even when the outer diameters of a top tube, a bottom tube, a seat tube, a chain tube, etc. have the thickness of a body frame of a classical bicycle, while relatively reducing the weight of the body frame. For this, the body frame for a bicycle according to the present invention is configured in such a way that each of the top tube, the bottom tube and the seat tube is made in a circular shape wherein the outer diameters are same from one end to the other end of each tube, and the flesh thickness of each tube is relatively thicker at the other end portion than one end portion, and each tube is made of a carbon material.