Unit 6 Engine

1、Unit 6 Engine Operation ContentsnI. New words & phrases nII. Text analysis nIII. Exercises I. New words & phrases nengine endin 發(fā)動機npiston pistn 活塞ncylinder silind 氣缸ncrankshaft krkft 曲軸nflywheel flawil 飛輪nstroke struk 沖程nsuction skn 吸入，吸收ncompression kmpren 壓縮nexhaust iz:st 排氣，廢氣nvalve vlv

2、閥門nignition gn()n 點火，點燃nlubrication ,lubrken 潤滑nconnecting rod 連桿nfour-stroke-cycle engine 四沖程循環(huán)發(fā)動機nintake valve 進氣口nexhaust valve 排氣口 II. Text analysis nInternal combustion engines are those that burn their fuel inside the engine. 內燃機：燃料在發(fā)動機氣缸內燃燒，所產生的燃氣直接推動活塞運動 External combustion engine 外燃機 e.g :

3、steam engine (uses a fire in a boiler rather than inside the engine) 在鍋爐燃燒而不是發(fā)動機Engine classification 發(fā)動機分類nNumber of cylinders 汽缸數(shù) single cylinder engine 單汽缸發(fā)動機 multicylinder engine 多汽缸發(fā)動機 ：雙缸，三缸，四缸。nArrangement of cylinders 氣缸排列順序 in-line engine 直列式發(fā)動機 V-type engine V 型發(fā)動機 Flat engine 水平對置式發(fā)動機nArr

4、angement of valves 進氣方式 1）naturally aspirated engine (NA engine) 自然吸氣式發(fā)動機：空氣靠活塞的抽吸作用進入氣缸內。汽油機常采用自然吸氣式。 2）supercharged engine 增壓式發(fā)動機：為增大功率，在發(fā)動機上裝有增壓器（supercharger)，使進入氣缸的氣體預先經(jīng)過壓氣機壓縮后再進入氣缸。柴油機為了提高功率常采用增壓式。nType of cooling 冷卻方式 1) liquid/coolant cooling engine ：以冷卻液（coolant)作為冷卻介質 2)air cooling engine

5、:以空氣作為冷卻介質 nNumber of cycles 實現(xiàn)循環(huán)的行程數(shù) two-stroke engine 二沖程發(fā)動機：活塞移動四個行程或曲軸轉兩圈氣缸內完成一個工作循環(huán) four-stroke engine 四沖程發(fā)動機：活塞移動兩個行程或曲軸轉一圈氣缸內完成一個工作循環(huán)n Type of fuel burned 所用燃料 gasoline engine 汽油機 diesel engine 柴油機nType of ignition 點火方式 spark-ignition engine 點燃式發(fā)動機:利用火花塞發(fā)出的電火花強制點燃燃料，使燃料強行著火燃燒。如汽油機。 compressio

6、n-ignition engine 壓燃式發(fā)動機：利用氣缸內空氣被壓縮后產生的高溫，使燃油自燃。如柴油機。The main parts of engines發(fā)動機的主要組成部分n1）the engine block 發(fā)動機體n2) the cylinder n3) cylinder head 汽缸蓋n4) the piston n5) the connecting rod n6) crankshaft n7) camshaft 凸輪軸n8) the fuel pump 燃油泵Five systems of the engines 發(fā)動機的五大系統(tǒng)nThe engines required ma

7、ny systems for their performance. These are： A. fuel system 燃油供給系 B. ignition system 點火系 C. lubricating (lubrication) system 潤滑系 D. cooling system 冷卻系 E. starting system 啟動系Four-stroke-cycle-engine nThe piston in cylinder makes four movements (two up and two down ) or two revolutions of the cranksha

8、ft for each combustion . ( 每一次燃燒活塞在氣缸內往返4個行程，即曲軸轉2轉）n Stroke refers to piston movement. A stroke occurs when the piston moves from one extreme position to the other inside the cylinder. 活塞在氣缸里從一頭運行到另一頭完成 一個沖程。nFour strokes: suction stroke (intake stroke): 進氣沖程 fresh mixture is sucked into the cylind

9、er through the open inlet valve 進氣門打開，排氣門關閉，活塞位于最高點，向下移動，然后混合氣體進入氣缸。 n compression stroke 壓縮沖程 the air-fuel mixture is squeezed into smaller and smaller volume 活塞向上運動，壓縮可燃混合氣，混合氣體溫度升高，為點火做準備nPower stroke 做功沖程 the mixture under pressure is ignited. The air-fuel mixture is burning and the expanding ga

10、ses push the piston down creating a power stroke. 高壓可燃混合氣被點燃，氣體膨脹推動活塞向下移動，完成做功沖程。nExhaust stroke 排氣沖程 the piston moves upward. Forcing the burned gases from the combustion chamber （燃燒室） through the exhaust valve. 活塞向上運動，排氣閥打開，廢氣被排出燃燒室。Necessary components of the four-stroke engine (四沖程發(fā)動機的必須部件）nFlyw

11、heel: since only the third stroke produces work, the piston needs help over the other strokes. This is given by a flywheel attached to the crankshaft , which stores up energy from power stroke; this energy then carries the piston through the three strokes until the next stroke caused by the combusti

12、on is repeated. 因為只有第三沖程做功，活塞在其他沖程需要幫助。由安裝在曲軸端部的飛輪提供這種幫助。飛輪在做功沖程吸收能量，這些能量可以帶動活塞通過三個沖程直到下一次燃燒nCamshaft (凸輪軸）： controls the cams that open or close valves to let gases in and out of the cylinder 控制著打開或關閉閥門使氣體進入或排出氣缸的凸輪補充nTDC：top-dead-center 上止點 the highest position that the piston reaches inside the c

13、ylinder nBDC： bottom-dead-center 下止點 the lowest position that the piston reaches inside the cylinder Homeworkn1. According to the type of cooling, engines can be divided into _ engines and air cooling engines. A. liquid cooling B. fan cooing C. oil cooling D. fuel cooling 2. The first stroke of the engine is_. A. intake stroke B. compr