Lesson2HowDoesaMarineDieselEngineWork剖析

1、Lesson 2 How Does a Marine Diesel Engine Work第2 課 船用柴油機(jī)是如何工作的1. The diesel engine is a type of internal combustion engine which ignites the fuel by injecting it into hot, high pressure air in a combustion chamber. The marine diesel engine is a type of diesel engine used on ships. The principle of it

2、s operation is as follows:1. 柴油機(jī)是一種內(nèi)燃機(jī), 通過把燃油噴入高溫高壓的燃燒室而發(fā)火。船用柴油機(jī)是一種在船上使用的柴油機(jī)。其工作原理如下：2. A charge of fresh air is drawn or pumped into the engine cylinder and then compressed by the moving piston to very high pressure.一定量的新鮮空氣被吸入或泵入氣缸并被運(yùn)動(dòng)的活塞壓縮至很高的壓力。3. When the air is compressed, its temperature rise

3、s so that it ignites the fine spray of fuel injected into the cylinder. The burning of the fuel adds more heat to the air charge, causing it to expend and force the engine piston to do work on the crankshaft which in turn drives the ship's propeller.空氣被壓縮時(shí), 溫度升高, 便點(diǎn)燃噴入氣缸的油霧。燃油的燃燒對缸內(nèi)空氣的加熱, 使空氣膨脹并

4、迫使發(fā)動(dòng)機(jī)活塞對曲軸做功, 隨之驅(qū)動(dòng)螺旋槳。4. The operation between two injections is called a cycle, which consists of a fixed sequence of events. This cycle may be achieved either in four strokes or two. In a four-stroke diesel engine, the cycle requires four separate strokes of the piston, i.e. suction, compression,

5、expansion and exhaust. As its name implies a two-stroke cycle takes place in two consecutive strokes of the engine piston, or one revolution of the crankshaft. Thus each operation in the cycle is repeated during every revolution of the engine. The two strokes of the cycle may be termed: Compression

6、stroke and power or expansion stroke.4. 兩次噴油期間的運(yùn)轉(zhuǎn)過程叫一個(gè)工作循環(huán)。它由一些程序固定的過程組成。這個(gè)循環(huán)可在二行程或四行程內(nèi)完成。四沖程柴油機(jī)的工作循環(huán)需要四個(gè)獨(dú)立的活塞行程, 即吸氣、壓縮、膨脹和排氣。正如其名稱所指，二沖程工作循環(huán)內(nèi)發(fā)動(dòng)機(jī)活塞完成兩個(gè)連續(xù)沖程，或曲軸轉(zhuǎn)一周。因此，每個(gè)循環(huán)的運(yùn)行隨著發(fā)動(dòng)機(jī)每轉(zhuǎn)一周而重復(fù)。這種循環(huán)的兩個(gè)沖程可稱為壓縮沖程和動(dòng)力或膨脹沖程。5. Its operation is as follows (see Fig. 2-1):5. 其工作原理如下(見圖2-1):1) The crankshaft is rev

7、olving clockwise and the piston is moving up the cylinder, compressing the charge of air. Because energy is being transferred into the air, its pressure and temperature increase. By the time the piston is approaching the top of the cylinder (known as top dead center or TDC) the pressure is over 100

8、bar and the temperature over 500.1) 曲軸順時(shí)針旋轉(zhuǎn)，活塞沿氣缸向上運(yùn)動(dòng)，壓縮充入的空氣。由于能量被轉(zhuǎn)移到空氣中，其壓力和溫度都增高。當(dāng)活塞接近氣缸頂部(稱為上止點(diǎn)或TDG)時(shí)，壓力達(dá)到100 bar以上，溫度超過500。2) Just before TDC fuel is injected into the cylinder by the fuel injector. The fuel is “atomized” into tiny droplets. Because they are very small these droplets heat up ve

9、ry quickly and start to burn as the piston passes over TDC. The expanding gas from the fuel burning in the oxygen forces the piston down the cylinder, turning the crankshaft. It is during this stroke that work energy is being put into the engine.2) 在活塞就要到達(dá)上止點(diǎn)之前，噴油器把燃油噴入氣缸。燃油被“霧化”成細(xì)小的液滴。這些液滴非常小，因而升溫很

10、快，在活塞經(jīng)過上止點(diǎn)時(shí)開始燃燒。燃油在氧氣中的燃燒使氣體不斷膨脹，迫使活塞沿氣缸向下運(yùn)動(dòng)，轉(zhuǎn)動(dòng)曲軸。正是在這一沖程期間發(fā)動(dòng)機(jī)獲得工作能量。3) As the piston moves down the cylinder, the useful energy from the burning fuel is expended. At about 110o after TDC the exhaust valve opens and the hot exhaust gas (consisting mostly of nitrogen, carbon dioxide, water vapour and

11、 unused oxygen) begins to leave the cylinder.3) 隨著活塞沿氣缸向下運(yùn)動(dòng)，燃油燃燒產(chǎn)生的有用能量被消耗掉。上止點(diǎn)后約110°，排氣閥打開，高溫廢氣(主要包括氮?dú)?、二氧化碳、水蒸氣和未使用的氧?開始離開氣缸。4) At about 1400after TDC the piston uncovers a set of ports known as scavenge ports. Pressurized air enters the cylinder via these ports and pushes the remaining exhau

12、st gas from the cylinder in a process known as “scavenging”. The piston now goes past bottom dead center and starts moving up the cylinder, closing off the scavenge ports. The exhaust valve then closes and compression begins.4) 上止點(diǎn)后約140°，活塞打開被稱為掃氣口的一組氣孔。增壓空氣通過這些氣孔進(jìn)入氣缸，推動(dòng)剩余的廢氣排出氣缸，這一過程被稱為“掃氣”?；钊?/p>

13、現(xiàn)在經(jīng)過了下止點(diǎn)并開始沿氣缸向上運(yùn)動(dòng)，關(guān)閉了掃氣口。隨后，排氣閥關(guān)閉，壓縮開始。6. The two-stroke cycle can also be illustrated on a timing diagram (see Fig. 2-2).二沖程循環(huán)也可以圖解為一個(gè)正時(shí)圖(見圖2-2 ) Fig.2-2 two-stroke cycle and timing diagrams圖2-2 二沖程循環(huán)正時(shí)圖12 Compression壓縮23 Fuel injection噴油34 Power動(dòng)力45 Exhaust排氣1. Approx 110° BTDC上止點(diǎn)前約110°

14、 2. Approx 10°BTDC上止點(diǎn)前約100°3. Approx 12° ATDG上止點(diǎn)后約120° 4. Approx 110° ATDG上止點(diǎn)后約110°5. Approx 140° ATDC上止點(diǎn)后約140° 6. Approx 140° BTDC止點(diǎn)前約140°7. The main difference between the two-stroke and the four-stroke cycles is the power developed. The two-stroke

15、 cycle engine, with one working or power stroke every revolution will, theoretically, develop twice the power of a four-stroke engine of the same swept volume. Inefficient scavenging however and other losses, reduce the power advantage to about 1.8. For a particular engine power the two-stroke engin

16、e will be considerably lighter-an important consideration for ships. Nor does the two-stroke engine require the complicated valve operating mechanism of the four-stroke. The four-stroke engine however can operate efficiently at high speeds, which offsets its power disadvantage; it also consumes less

17、 lubricating oil.7. 二沖程和四沖程循環(huán)的主要區(qū)別是產(chǎn)生的功率不同。每轉(zhuǎn)有一個(gè)工作或做功沖程的二沖程發(fā)動(dòng)機(jī)理論上產(chǎn)生的功率是同樣容積排量的四沖程發(fā)動(dòng)機(jī)的兩倍。然而，掃氣不充分和其他損失使這一優(yōu)勢降到大約1.8倍。對于特定的發(fā)動(dòng)機(jī)功率，二沖程發(fā)動(dòng)機(jī)的重量輕得多，這是船舶一個(gè)重要的考慮因素。二沖程發(fā)動(dòng)機(jī)也不需要四沖程發(fā)動(dòng)機(jī)那樣復(fù)雜的氣閥操縱機(jī)構(gòu)。然而，四沖程發(fā)動(dòng)機(jī)能夠在高速下高效運(yùn)轉(zhuǎn)，抵消了其功率的不足;而且其潤滑油的消耗量較少。8. Each type of engine has its applications, which on board ships have resul

18、ted in the slow speed (i. e. 80-100 r/min) main propulsion diesel operating on the two-stroke cycle. At this low speed the engine requires no reduction gearbox between it and the propeller. The four-stroke engine (usually rotating at medium speed, between 250 and 750 r/min) is used for auxiliaries s

19、uch as alternators and sometimes for main propulsion with a gearbox to provide a propeller speed of between 80 and 100 r/min.每種柴油機(jī)都有其應(yīng)用。在船上，低速(即80-100 r/min)主推進(jìn)柴油機(jī)以二沖程工作。在此低速下，機(jī)槳間不需減速箱。四沖程柴油機(jī)(通常以中速運(yùn)轉(zhuǎn)，轉(zhuǎn)速為250-750 r/min)用于輔助機(jī)械，如交流發(fā)電機(jī)，有時(shí)作主推進(jìn)裝置，用減速箱提供80-100 r/min的螺旋槳速度。Task 1 Reading Comprehension任務(wù)1閱讀理解

20、A. Topics for Discussion A.討論話題1. What does the term “cycle” mean?1.“循環(huán)”這一術(shù)語是什么意思?The operation between two injections is called a cycle.2. Please name the four strokes of a four-stroke diesel engine according to their sequence.2.請按順序說出四沖程柴油機(jī)的四個(gè)沖程。The four strokes are: suction, compression, expansio

21、n and exhaust.3. How many revolutions of the crankshaft does it take for a two-stroke engine to complete one power stroke? What about a four-stroke one?3.二沖程柴油機(jī)完成一個(gè)動(dòng)力沖程曲軸需轉(zhuǎn)幾轉(zhuǎn)?四沖程柴油機(jī)呢?For a two-stroke engine, it takes one revolution of the crankshaft to complete one power stroke.For a four-stroke eng

22、ine, it takes two revolutions of the crankshaft to complete one power stroke.4. Among the four strokes of a four-stroke diesel engine, which strokes are the downward strokes and which strokes are the upward strokes4. 四沖程柴油機(jī)四個(gè)沖程中，哪些沖程是下行沖程，哪些是上行沖程?Among the four strokes of a four-stroke diesel engine

23、, suction and expansion strokes are the downward strokes and compression and exhaust strokes are the upward strokes?5. Say something about the comparison of two-stroke and four-stroke cycles.5.說說二沖程與四沖程循環(huán)的對比。The main difference between the two-stroke and the four-stroke cycles is the power developed

24、. develop twice the two-stroke cycle engine, with one working or power stroke every revolution will, theoretical of a four-stroke engine of the same swept volume.B. Multiple Choice B.選擇題Questions 1-5 are based on paragraphs 1-4. 根據(jù)課文第1-4段回答問題1-51. The diesel engine is a type of . 柴油機(jī)是一種。答案:DA. turbi

25、ne engine渦輪機(jī)B. gas turbine.燃?xì)廨啓C(jī)C. steam engine.蒸汽機(jī)D. internal combustion engine內(nèi)燃機(jī)2. The operation between two fuel injections is called . 兩次噴油之間的操作叫_。答案:BA. a power stroke一個(gè)做功沖程B. a working cycle一個(gè)工作循環(huán)C. circulation 循環(huán)D. a sequence一個(gè)順序3. In a four-stroke engine, the cycle of events is completed in

26、four strokes of 四沖程柴油機(jī)中，循環(huán)是在_的四個(gè)沖程內(nèi)完成的。答案:CA. the cylinder氣缸B. the crankshaft曲軸C. the piston活塞 D. the crosshead十字頭4. In the four-stroke engine, it takes to make one power stroke四沖程柴油機(jī)曲軸轉(zhuǎn)_做一個(gè)做功沖程。答案.CA. one propulsion一次推進(jìn) B. two propulsions.兩次推進(jìn)C. two revolutions 兩轉(zhuǎn)D. one revolution一轉(zhuǎn)5. A charge of f

27、resh air is drawn or pumped into the engine cylinder and then by the moving piston to very high pressure. 一定量的新鮮空氣被吸入或泵入柴油機(jī)氣缸，并被運(yùn)動(dòng)的活塞至很高的壓力。A. suctioned 吸入 B. compressed壓縮C. exhausted 排出 D. expanded.膨脹6. Compression takes place in the cylinder through the motion of the piston壓縮沖程通過活塞沿氣缸的_運(yùn)動(dòng)來進(jìn)行。答案.B.

28、A. downward下行B. upward上行C. inward向里D. outward向外7. During working, when the piston is near the , the air ignites the fine spray of fuel工作時(shí)，當(dāng)活塞靠近時(shí)，氣缸內(nèi)的空氣點(diǎn)燃細(xì)霧狀的燃油。答案.AA. TDCB. DTCC. BDCD. BCD8. For an ordinary four-stroke engine the exhaust valves open .對于一般的四沖程柴油機(jī)，排氣閥在_打開。答案:DA. after TDCB. before TDC

29、C. after BDCD. before BDC9. In which stroke is the working energy being put into the engine? 柴油機(jī)從哪一沖程中得到工作能量?答案:CA. Suction. 吸氣B. Compression壓縮。C. Expansion.膨脹D. Exhaust. 排氣10 When the piston of an engine is at the lowest point of its stroke, the engine is said to be on . 當(dāng)活塞在沖程的最低點(diǎn)時(shí)，就說成是柴油機(jī)處于_。答案:A

30、A. bottom dead center下止點(diǎn)B. inner dead center總固容量C. outer dead center 外止點(diǎn)D. TDC上止點(diǎn)Questions 11-14 are based on paragraphs 6-8.11. The two-stroke cycle engine, with one working or power stroke every revolution will, theoretically, develop the power of a four-stroke engine of the same swept volume. 每轉(zhuǎn)有

31、一個(gè)工作或做功沖程的二沖程發(fā)動(dòng)機(jī)理論上產(chǎn)生的功率是同樣容積排量的四沖程發(fā)動(dòng)機(jī)的。答案-CA. as much as 一樣多B. less than少于C. twice兩倍D. more than12. For a particular engine power the two-stroke engine will be considerably lighter. the complicated valve operating mechanism of the four-stroke. 對于特定的發(fā)動(dòng)機(jī)功率，二沖程發(fā)動(dòng)機(jī)的重量輕得多，_四沖程發(fā)動(dòng)機(jī)那樣復(fù)雜的氣閥操縱機(jī)構(gòu)。答案.BA. Nor t

32、he two-stroke engine requires二沖程發(fā)動(dòng)機(jī)也不需要(語法錯(cuò)誤)B. Nor does the two- stroke engine require二沖程發(fā)動(dòng)機(jī)也不需要(本題因否定詞nor放在句首，應(yīng)采用倒裝句式)C. Nor the two- stroke engine require二沖程發(fā)動(dòng)機(jī)也不需要(語法錯(cuò)誤)D. Nor do the two-s stroke engine require二沖程發(fā)動(dòng)機(jī)也不需要(語法錯(cuò)誤)13. Each type of engine has its applications, which on board ships hav

33、e resulted in the slow speed main propulsion diesel operating cycle. .每種柴油機(jī)都有其應(yīng)用。在船上，低速主推進(jìn)柴油機(jī)_工作。答案:CA. on the four-stroke以四沖程B. in the two-stroke以二沖程（介詞應(yīng)用on)C. on the two-stroke以二沖程D. either on the two-stroke or on the four-stroke以二沖程或四沖程14. The four-stroke engine is used for auxiliaries such as al

34、ternators and sometimes for main propulsion with to provide a propeller speed of between 80 and 100r/min. 四沖程柴油機(jī)用于輔助機(jī)械，如交流發(fā)電機(jī)，有時(shí)作主推進(jìn)裝置，用提供80 - 100 r/min的螺旋槳速度。答案:DA. a control box控制箱B. a governor調(diào)速器C. a monitor 監(jiān)控器D. a gearbox減速箱Task 2 Vocabulary and Structure任務(wù)2詞匯與結(jié)構(gòu)A. Technical Terms A.專業(yè)術(shù)語Transla

35、te the following into Chinese. 將下列詞組譯成漢語。1. valve operating mechanism 閥操縱機(jī)構(gòu)2. internal combustion engine內(nèi)燃機(jī)3. combustion chamber燃燒室4. top dead center上止點(diǎn)5. fuel injector噴油器6. exhaust valve排氣閥7. working or power stroke工作或做功沖程8. swept volume容積排量B. Active Words B.常用詞Complete the following sentences by f

36、illing in the blanks with the words in the table. Change the form of the words if necessary. 從框中選詞完成句子，如有必要改變詞的形式。Ignite compress inject atomize offset1. The diesel engine is a type of internal combustion engine which it into hot, high pressure air in a combustion chamber.1. ignites, injecting柴油機(jī)是一種

37、內(nèi)燃機(jī)，通過把燃油噴入高溫高壓的燃燒室而將其點(diǎn)燃。2. The four-stroke however can operate efficiently at high speed, which its power disadvantage. 2. offsets然而，四沖程發(fā)動(dòng)機(jī)能夠在高速下高效運(yùn)轉(zhuǎn)，抵消了其功率的不足。3. Just before TDC fuel is injected into the cylinder by the fuel injector. The fuel is into tiny droplets.3. atomized 在活塞就要到達(dá)上止點(diǎn)之前，噴油器把燃油噴

38、入氣缸。燃油被霧化成細(xì)小的液滴。4. When the air is its temperature rises so that it ignites the fine spray of fuel injected in to the cylinder.4. compressed空氣被壓縮時(shí)，溫度升高，便點(diǎn)燃噴入氣缸的細(xì)霧狀的燃油。Understand the phrases by studying the sentences below and translate the phrases into Chinese. 通過學(xué)習(xí)下面的句子理解短語，并將短語譯成漢語。1. by the time:

39、 1.到時(shí)候?yàn)橹?，等到e. g. By the time the piston is approaching the top of the cylinder, the pressure is over 100 bar and the temperature over 500.例如:到活塞接近氣缸頂部時(shí)為止，壓力超過100 bar,溫度超過500。2. in turn: 依次，輪流e. g. The burning of the fuel adds more heat to the air charge, causing it to expand and force the engine piston to do work on the crankshaft which in turn drives the ships propeller.例如:燃油的燃燒給缸內(nèi)空氣加入了更多的熱量，使空氣膨脹并迫使發(fā)動(dòng)機(jī)活塞對曲軸做功，隨之驅(qū)動(dòng)螺旋槳。3. as follows: 列舉如下e. g. The principle of its operation is as