機車噴油引擎噴霧觀測與動態油膜模式建立

Fuel Spray Observation and Development of Fuel Film Dynamic Model for Motorcycle EFI System

葉心丞(Hsin-Cheng Yeh)

指導教授 ： 吳浴沂

國立臺北科技大學/機電學院/車輛工程系所/碩士(2007年)

摘要

電子燃油噴射系統相較於化油器引擎來說，可以提供準確且及時的燃油量，但當引擎在暫態運轉條件下操作時，進氣道內之壁濕現象會影響實際進入汽缸的空燃比，也因此影響到汽缸內的燃燒狀況與廢氣汙染物的排放。本研究將針對機車噴油引擎觀察其噴油嘴的噴霧特性，以及噴束在自由空間和限制空間內的噴霧狀況。並利用Matlab/Simulink所建構的油膜動態模型，使用燃油擾動法求出管壁上的燃油沉積比例與油膜蒸發常數。分別藉由以上定性以及定量的方式來探討歧管內的壁濕現象。實驗結果發現，針對進氣歧管以及進氣道幾何形狀，選擇適當的噴油嘴以及噴束型態，且將噴束對準汽門背噴射，將會減少壁濕現象的發生；引擎轉速會對油膜模型特性參數有重要影響，轉速愈快，沉積在管壁上的油膜量愈少，且從油膜上揮發的燃油愈多；節氣門開度與噴油量變化對於油膜參數的影響在本研究中並不明顯。

關鍵字

機車引擎 ； 電子燃油噴射系統 ； 壁濕現象 ； 油膜動態模型 ； 參數標定

並列摘要

The advantages of fuel injection system can offer more accruate and prompt fuel amount then that of carburetor. However, when the engine is operated under the transient operation condition, the wall wetting effect will influence the in-cylinder air fuel ratio. The wrong air fuel ratio will cause higher exhaust emissions and worse driveability. So, this paper will investigate the fuel dynamics in engine. The observation of spray pattern is performed in free and limited space. Then the fuel film dynamic model is used to correct the transient fueling step and simulate the in-cylinder air fuel ratio. The deposit factor and boiling time constant is determined by means of step change of fuel injection and measuring the exhaust gas air fuel ratio. The experimental result shows that choose the injector with proper spray pattern, and then aim at the inlet valve will reduce the wall wetting. The engine speed have important influence on parameter of fuel film dynamic model. and decreases with increasing engine speed, but weakly dependent upon injected fuel amount and throttle position.

並列關鍵字

Electronic Fuel Injection system ； Motorcycle engine ； Wall wetting ； Fuel Film dynamic model ； Parameters determination

參考文獻

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