您相信有人用手工一齒一齒的刻出齒片的上/下鏈導角嗎 ?
這神乎奇技我在新竹"老學長"見識到.

每個導角軌道均是3D的曲線, 機器無法辦到.

不信邪的, 去體驗一下何謂如利刃切豆腐, 行雲流水般的變速.


Internet上的資料, 少的可憐...
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作者姓名:游國宏
論文名稱:自行車後變速系統飛輪組齒形之整合設計
論文名稱:Computer-Integrated Design of the Freewheel of a Bicycle
     Rear Derailleur System

 
[摘要]
飛輪齒形之設計對變速性能有決定性的影響,一般可區分為上鏈齒形和下
鏈齒形二種。結合上、下鏈功能於同一飛輪組時,在鏈輪相角、齒尖導角
以及路徑規劃等諸多方面是彼此互相衝突矛盾的,故整合上、下鏈之齒形
設計相當具有挑戰性。本文建立一套完整的齒形設計方法,以提高換鏈之
平順性及穩定性為目標,設計出兼具上鏈及下鏈功能之飛輪齒形。設計的
方法,首先分析各組件對換鏈性能的影響,並定義各組件相關之參數,接
著探討非換鏈點的問題,分析影響齒尖導角的參數,以解決非換鏈點齒尖
導角相違背的現象。在齒形設計方面,採用非直線形換鏈路徑為基礎,設
計兼具上、下鏈之飛輪齒形,並且提出一種較為穩定的換鏈模式,解決非
直線形路徑在支承上的困難,用以提高換鏈的穩定性。根據以上的設計準
則,以CAD/CAM進行原型品的設計與製造,經測試之結果,該齒形在功能
上具有良好的效果,驗證了本文設計理念的正確性與可行性。
[摘要]
The sprocket design of the freewheel of the rear derailleur
system possessing a specified tooth profile for the up- and
down-shifting motions is determinate to the shifting
performance of a bicycle. The design variables, such as
sprocket phase angle, chamfers on the sprocket teeth, and
shifting path, etc., conflict with each other when designing a
freewheel providing both up- and down-shifting performance. In
this study, a comprehensive design method for trimming the
sprocket teeth was established to improve the smoothness as
well as the stability in both the up-shifting and down-
shifting. First, the parameters of the relevant components
were defined and their effects on the shifting performance were
analyzed. To solve the problem in the violation of chamfer
trimming, the parameters that affect the trimming values on the
tips of the " nonshifting " teeth were analyzed, too. The
sprocket design that integrated both the up-shifting and down-
shifting perform- ance was based on the nonlinear shifting
path. A mathematical model for stable shifting was also
proposed to overcome the difficulty in supporting such a
design. The prototype designed and manufactured by CAD/CAM
according to the proposed design methodology was tested and
verified to have excellent performance. Thus, it proved the
feasibility and accuracy of the design methodology developed in
this thesis.

 

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