使用電子氣閥之汽油引擎汽門正時最佳化分析

Optimization of Valve Timing for SI Engines with Electromagnetic Valves

單忠仁(Chung-Jen Shan)

指導教授 ： 蕭耀榮

國立臺北科技大學/機電學院/車輛工程系所/碩士(2007年)

摘要

傳統機械式可變汽門正時系統為分段固定式機構，無法根據引擎轉速以及負載變化來提供適當的汽門正時;利用電磁式氣閥(electromagnetic valve)可根據引擎當時狀況控制進排氣門的開啟與關閉正時以及汽門持續開啟正時，因此引擎在冷啟動廢氣排放、怠速穩定性、燃油消耗率以及引擎性能等方面均相當之改善。在引擎中低轉速時，氣體流動性差，調整進氣量的節流閥機構易使引擎泵損失(pumping lose)增加，若電磁式氣閥搭配無節流閥(non-throttled)引擎，汽缸內的進氣量直接由氣閥控制，可以有效提升引擎性能以及降低泵損失。
本研究建立配有電磁式氣閥的四行程多缸無節流閥引擎動態模型，分析引擎在低、中、高轉速下，改變進氣閥開閉正時對引擎容積效率、馬力、扭力以及燃油消耗率的影響。電磁式氣閥在進氣閥開啟時與排氣閥關閉時有可能與活塞產生撞擊，因此本研究分析電磁式氣閥與活塞兩者動態行為，可建立進氣閥最小延遲開啟角度及最大提前開啟角度，排汽閥最小提早關閉角度及最大延遲關閉角度與轉速之間關係，再使用田口法求得引擎低、中、高轉速下，進氣閥最大提前角度範圍內的進氣閥正時最佳化，因此經過引擎模擬系統分析出的汽門正時未來可運用到實際無節流閥引擎。

關鍵字

可變汽門正時 ； 無節流閥引擎 ； 田口法

並列摘要

By utilizing electromagnetic valve, we can control opening and closing timings of intake and exhaust valves according to the operating situation of the engine. Therefore, the engine performance can be improved suitably in exhaut emission during starting, idle stability, fuel comsumption and engine power, etc. When an engine rotates in the low speed, gas flow is bad and the throttle which adjusts air mass is apt to cause the pumping lose of the engine. If an electromagnetic valve is collocated with an non-throttled engine, the air mass in the cylinder could controlled by the inlet valves directly, improved engine performance, and reduced the pumping lose effectively.
This research sets up a four-stroke unthrottled engine model equipped with electromagnetic valves, In this research, we analyses the influence on the engine volumetric efficiency, house power, torque and fuel comsumption by changing the opening and closing timing of the intake valves when the engine rotates in low, medium and high speed.However, if an electromagnetic valve is opened or closed unproprely, it will hit piston top surface and then damage the corresponeding valve.Thus, this research analyze the dynamic behaviors between the electromagnetic valve and piston, It proposes the intake processes of maximum IVO in degree before TDC as function of the engine speed and exhaust processes of maximum EVC in degree after TDC as function of the engine speed .
We then propose a method to determine the limits of IVO timing in intake stroke and timing in exhaust stroke.
Finally, Taguchi Method is applied to get optimization of intake valve timing for engine rotated in the low, medium, and high speed. So that the optimization of valve timing analysed from engine model system can be applied to non-throttled engines in the future.

並列關鍵字

Electromagnetic Valve ； Non-throttled Engines ； Taguchi Method

參考文獻

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[3]. J. B.Heywood., Internal Combustion Engine Fundamentals, New York McGraw-

Hill Book Company.,1988.

Timing System Using Electromagnetic Mechanism” SAE technical paper series

2004-01-1869, 2004.