Please use this identifier to cite or link to this item: http://hdl.handle.net/11455/1490
標題: 單缸二行程引擎二次空氣系統設計之分析
The Design Analysis of Secondary Air Injection System for Single Cylinder Two Stroke Engine
作者: 張聖宗
Chang, Sheng-Tsung
關鍵字: Secondary Air Injection System
二次空氣系統
reed valve
Two Stroke Engine
簧片閥
二行程引擎
出版社: 機械工程學系
摘要: 自第三期機車污染排放標準實施後,觸媒與二次空氣系統在機車污染排放控制系統上的重要性更為顯著,二次空氣系統可在排氣管中提供應額外的空氣,使排氣中O2的濃度增加,協助觸媒將CO與HC氧化,目前機車大部份都採用自然進氣式的二次空氣系統,是利用排氣管內的瞬時負壓使簧片閥開啟吸入空氣,排氣管內正壓時簧片閥會關閉以避免回流發生。 本文針對在實際引擎運轉下,探討二次空氣系統設計參數對二次空氣流量特性的影響,以及二次空氣系統對引擎污染排放的影響,另外也進行二次空氣系統中簧片閥動態特性的量測與數值計算分析,以提供設計時簧片特性選擇之參考。 簧片閥模擬計算的結果可發現,四階懸臂樑模式計算的結果很好,不論是簧片的開度大小或開啟相位都與量測值相當接近,計算與量測的簧片開度誤差在0.4mm以下,而二階系統計算的波形與量測的波形有一段差距,會有結合開啟與延後關閉的狀況,使得簧片的最大開度增加,造成較大的誤差,由此看來四階懸臂樑模式較能描述簧片閥的動態特性。 量測結果發現,不同的導管長度對於二次空氣流量大小與轉速的關係會有影響,流量曲線下凹的位置會不同,隨著管長越長下凹的點會在更高的轉速發生,而導管管徑與導管注入位置的影響不大,只會改變流量大小,但波形相位改變不大。在引擎性能方面,二次空氣導管管徑對引擎扭力影響最大,注入口位置在高轉速有影響,而管長則影響不大。在污染排放方面,在中低負載時二次空氣系統有較明顯的功用,全負載時改善效果較小。另外,在加裝二次空氣系統後,觸媒耐熱溫度的考量相當重要。
Since the third stage of motorcycle emissions regulation has been issued, the catalytic and secondary air injection system(SAIS) become important parts of the emission control system of motorcycles. The function of the air injection system is to provide extra air prior to the catalytic converter to promote the oxidation of CO and unburned hydrocarbons. Most SAIS of the motorcycles is of the natural aspiration type, i.e., air are sucked into the exhaust pipe without boosting. A reed valve is used to prevent the reverse flow in the system. The purpose of this study is to investigate the effects of design parameters on the characteristic of the flow quantity of the SAIS, and studying the effect of injected air on the improvement of engine exhaust emission in the firing engine. In addition, both experiments and numerical calculations of the reed valve will be carried out. Results of numerical calculations show that the “cantilever beam” mode has a good correlation between measured and predicted reed lift at all speeds. The “2nd order system” mode can't simulate the vibration of the reed valve. It occurs delays of closing points and gets more errors. Therefore, the “cantilever beam” mode can describe dynamic characteristic of the reed valve. Results of experiment show that the intake duct length affects the relationship between air flow quantity and rpm of engine, and do little effect of the intake duct diameter and intake position. In the engine performance direction, intake duct diameter has great effect on the torque, and intake position does when the engine runs in higher rpm. The intake duct length has little effect. SAIS can improve the catalyst converter when the engine runs in lower load and do little effect when engine runs in higher load. Besides, it is important to take account of the heatproof temperatures of the catalyst after used the SAIS.
URI: http://hdl.handle.net/11455/1490
Appears in Collections:機械工程學系所

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