A rotary engine is an internal combustion engine, but it works in a completely different way than the conventional piston engine.
In a piston engine, the same volume of space (the cylinder) alternately does four different jobs -- intake, compression, combustion and exhaust. A rotary engine does these same four jobs, but each one happens in its own part of the housing. It's kind of like having a dedicated cylinder for each of the four jobs, with the piston moving continually from one to the next.
As the rotor moves through the housing, the three chambers created by the rotor change size. This size change produces a pumping action. Let's go through each of the four strokes of the engine looking at one face of the rotor.
Intake
The intake phase of the cycle starts when the tip of the rotor passes the intake port. At the moment when the intake port is exposed to the chamber, the volume of that chamber is close to its minimum. As the rotor moves past the intake port, the volume of the chamber expands, drawing air/fuel mixture into the chamber.
When the peak of the rotor passes the intake port, that chamber is sealed off and compression begins.
Compression
As the rotor continues its motion around the housing, the volume of the chamber gets smaller and the air/fuel mixture gets compressed. By the time the face of the rotor has made it around to the spark plugs, the volume of the chamber is again close to its minimum. This is when combustion starts.
Combustion
Most rotary engines have two spark plugs. The combustion chamber is long, so the flame would spread too slowly if there were only one plug. When the spark plugs ignite the air/fuel mixture, pressure quickly builds, forcing the rotor to move.
The pressure of combustion forces the rotor to move in the direction that makes the chamber grow in volume. The combustion gases continue to expand, moving the rotor and creating power, until the peak of the rotor passes the exhaust port.
Exhaust
Once the peak of the rotor passes the exhaust port, the high-pressure combustion gases are free to flow out the exhaust. As the rotor continues to move, the chamber starts to contract, forcing the remaining exhaust out of the port. By the time the volume of the chamber is nearing its minimum, the peak of the rotor passes the intake port and the whole cycle starts again.
The neat thing about the rotary engine is that each of the three faces of the rotor is always working on one part of the cycle -- in one complete revolution of the rotor, there will be three combustion strokes. But remember, the output shaft spins three times for every complete revolution of the rotor, which means that there is one combustion stroke for each revolution of the output shaft.
【中文註解】
旋轉式發動機是一種內燃型發動機,但是它與傳統的活塞式發動機完全不同。
對於活塞式發動機來說,它的氣缸內部空間本身承擔著四個不同的工作——進氣、壓縮、燃燒與排氣。不過旋轉式發動機也有這四大工作,但是這些工作是在發動機內不同的空間內進行的。
旋轉式發動機的轉子在氣缸室內轉動時,轉子與缸壁之間開成的氣室的大小可以隨著轉子轉動改變。氣室的大小轉變可以產生泵吸作用。
進氣
當轉子的邊緣經過進氣口始,整個做功循環的吸氣環節就開始了。此時,進氣口與氣缸內室連通,此時這個氣室的容積最小,當轉子轉過進氣口時,氣室的體積開始擴大,吸入空氣燃汽混和氣。當轉子的最頂點轉過進氣口時,這個氣室開始封閉,並進入壓縮狀態。
壓縮
轉子繼續在氣缸內運動,該氣室的體積變小,裡面的混和氣體開始進行壓縮,當轉子的面快轉到火花塞時,氣室的體積再次接近最小值,這時燃燒環節就要開始。
燃燒
大部分旋轉式發動機都有兩個火花塞。如果只有一個火花塞,而燃燒室比較狹長,燃燒就會會延緩進行。事實上,火花塞一旦引燃混和氣體,燃燒室內壓力迅速加大,迫使轉子轉動。
氣室內壓力增大,迫使轉子向使氣室裡體積增大的方面轉動。燃燒的氣體繼續增大,使得轉子移動,並生產能量。直到轉子的頂點經過排氣口。
排氣
當轉子頂端通過排氣口時,高壓的燃氣會從排氣口排出。氣室的體積繼續減小,迫使剩餘的氣體排出氣室。當氣室的體積達到最小時,轉子的頂點經過進氣口,整個循環重新開始了。
【延伸閱讀】
* 汽車的心臟——發動機
* 發動機原理及詳解之一
* 發動機原理及詳解之二
* 發動機原理及詳解之三
* 發動機原理及詳解之四
本文地址:https://auto.gasgoo.com/news/b/2008-5-21/39baaa45-75eb-48b3-a1b0-484c6753284e.shtml