| Summary: | 碩士 === 國立臺北科技大學 === 車輛工程系所 === 95 === 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.
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