變速自行車鏈條設計

Abstract

本論文主要研究對象為自行車上傳動系統中的鏈條元件，由於自行車飛輪受到車架、騎乘姿勢所形成的空間限制，必須在有限空間內增加飛輪片數增加齒數比，達到變速換檔的舒適性。因此，為了配合這樣緊密的飛輪，鏈條寬度的縮減是必須的。經過專利的整理後，確定空間尺寸和強度為初步設計的主要需求；提出不同的概念設計，並利用新的鏈條連結機構來達到鏈條寬度的縮減。 本文提出概念設計較目前市面上自行車最窄的鏈條寬度更窄，；強度部份利用有限元素分析法做定性分析，比較各個設計的相對強度；此外也經由原型的製作，檢視其機構的問題。

This study focuses on the chain for the multi-speed bicycle. Design space for the freewheel on bicycle is limited by frame, riding posture, etc. However, the number of gear ratios in this design space increased with added more sprockets are the trend on the bicycles. Therefore, reduction of chain width is necessary for working with this compact freewheel,. Space and strength are main requirements in the beginning of design according to literatures and patents review. Several new concepts are proposed, and these concepts use the linkage mechanism to achieve the reduction of chain width. Chain width of these concepts proposed in this study can be reduced under the assumption for fixed design space and thickness of sprockets. The finite element method is used to compare the trend of strength among these concepts. Mechanism problem for the concept design can observe from the prototype.