臺灣博碩士論文加值系統

皮帶式無段變速器(CVT)具有換檔平順,構造簡單,操作容易,重量輕,少維
修等優點,這些正是促成速克達機車在台灣及東南亞地區普及的主因.但長
期以來,CVT的效率不佳似乎是無法克服的難題,也是安裝於電動機車的最
大障礙.本研究即是企圖在不犧牲CVT特點的情況下,有效提升其效率.為了
釐清CVT效率低落的原因,本研究將功率損失分為速度損失與扭力損,並借
用V型皮帶驅動器的運動特性,以解釋各項損失的成因.由這些運動特性知,
皮帶沿切線方向之滑移是影響速度損失的主要原因,皮帶之彎曲遲滯損失
則是造成扭力損失的最大因子.在進行實驗之前,為了使數據合理可信,設
備的不準度、實驗的重複性等都列入考慮;而為了確保實驗狀態能配合實
際的騎乘條件,文中預先計算各行車型態下的車輛負載.田口試驗及靜態實
驗都是用來分析各參數對效率的影響;至於動態實驗不僅可提供換檔期間
及實際行車時的效率狀況,更能再次驗證靜態實驗中所得到的結果.基於理
論及實驗可知,CVT的高效率是發生於高扭力而低轉速,且減速比接近1時.
欲使CVT始終工作在這種效率較高的操作區,就必須調整其減速比範圍,並
配合調整傳動系統,才能大幅提升效率,同時又維持傳動系統所需的總減速
比.文中提出的前級減速齒輪及兩段式變速器都能提供這類功能.而兩個測
試實驗更明顯展示了這種改善設計對提升CVT效率的效益.此外,若考慮匹
配問題,必須使用設計軟體,修正CVT的部參數,才能使改善設計更為完整.

The advantage of smoother speed change,simpler mechanisms,
easier operation,lighter weight,lower cost and less maintenance,
etc., may be the main reasons for the rubber V-belt
continuously variable transmission (CVT) being popular in most
Asia countries. However,the low efficiency of the CVT has been
a serious problem and is actually the major barrier for the
installation of the CVT on the electrical motorcycle.The object
of this research is to improve the efficiency of CVT without
deteriorate any advantages. To understand the reasons for low
efficiency,the power loss was divided into speed loss and
torque loss,and the motion characteristics of the V-belt drive
were introduced to explain the loss mechanisms.The uncertainty
of each instrument and the repeatability of the experimental
setup were investigated to ensure the reliability of
experimental data.The external loading was also calculated
according to the driving pattern to simulate the actual road
conditions.The effects of the parameters on the efficiency of
the CVT were analyzed by both Taguchi method and steady-state
experiments.This test not only revealed the trend of the
efficiency during the interval of speed-ratio change but also
verified the results from prior experiments. Based on the
theoretical and experimental analysis,the key method for the
improvement may be the adjustment of speed ratio. To fulfill
this idea,the parameters of the CVT must be modified to
maintain the speed ratio of the entire power train.