【正文】 LESSON 1 Diesel engines The majority of ships around the world continue to be powered exclusively by diesel engines. 世界范圍內(nèi)大多數(shù)船舶都是采用柴油機(jī)作為動(dòng)力。 The predominance of diesel engines has e from improved engine efficiencies and designs pared to other forms of propulsion such as steam or gas turbines. 與蒸汽機(jī)、燃?xì)廨啓C(jī)等形式的動(dòng)力裝置相比，無(wú)論是效率上的提高，還是設(shè)計(jì)上的進(jìn)步，柴油機(jī)都體現(xiàn)出了一定的優(yōu)勢(shì)。 Many binations and configurations of diesel engine power plant exist. All provide the energy to do the work of moving the ship using diesel engines. 存在有很 多種聯(lián)合形式及結(jié)構(gòu)形式的柴油機(jī)動(dòng)力裝置，他們都能夠利用柴油機(jī)為船舶提供推動(dòng)力。 Slow speed diesel engines 低速柴油機(jī) Slow speed diesel engines are large, especially tall, and heavy and operate on the twostroke cycle. 低速柴油機(jī)是體積較大、缸體較長(zhǎng)、機(jī)身較重的二沖程柴油機(jī)。 These are the largest diesel engines ever built. Engine powers up to 100 000kw are available from a single engine. 它們是已建造過(guò)的最大型的柴油機(jī)，它們的單機(jī)可用功率可達(dá) 100000 kw。 They are tall to allow for long strokes which improve engine efficiency .the large physical allow for long strokes which improve engine efficiency. 較長(zhǎng)的缸體 能提供一個(gè)較長(zhǎng)的沖程，有助于提高柴油機(jī)的效率。 The large physical size of the engine and ponents leads to slow rotational speed with speeds up to 300rpm considered to be slow. 柴油機(jī)及其部件的物理體積較大，導(dǎo)致其回轉(zhuǎn)速度較低，盡管能夠加速到 300 rpm，但還是被認(rèn)為是低速機(jī)。 For equivalent power output, the twostroke diesel engine is significantly lighter than its parable fourstroke relative. 對(duì)于相同的功率輸出，相對(duì)于四沖程柴油機(jī)，二沖程柴油機(jī)的重量明顯輕很多。 This is most apparent for large power requirements where the twostroke engine produces much more power for the same weight. 對(duì)于大功率需求場(chǎng)合這是一個(gè)最明 顯的優(yōu)勢(shì)，二沖程柴油機(jī)能夠在相同的重量情況下，發(fā)出更大的功率。 Large, slow speed, twostroke marine diesel engines offer the advantages of： 大型、低速、二沖程船用柴油機(jī)的優(yōu)點(diǎn)如下： 1. Burning poorer quality, cheaper fuel 燃燒劣質(zhì)、低價(jià)的燃油 2. Providing large power from a single, less plicated machine prising fewer individual cylinders and moving parts 一個(gè)僅有幾個(gè)獨(dú)立汽缸和運(yùn)動(dòng)部件組成的、低復(fù)雜程度的柴油機(jī)就能提供較大的功率。 3. Having a low rotational speed allowing them to be directly coupled to the propeller and removing the need for transmission machinery such as clutches and gearboxes etc, 回轉(zhuǎn)速度較低 ，能夠直接和螺旋槳連接，不需要像離合器、齒輪箱等的中間傳動(dòng)機(jī)構(gòu)。 4. Being reversible and thus eliminating the need for reversing gear or controllable pitch propellers. Merchant ships driven by slow speed diesel engine will usually have a single large main engine directly coupled to a single fixed pitch propeller. The thrust forces from the propeller will be transferred to the hull of the ship through a thrust bearing built into a thrust block, the thrust block may be built as part of the slow speed engine, and this system is supported by diesel generators providing the ship‘s electrical power. 因?yàn)槟軌虻罐D(zhuǎn)，所以就不需要換向機(jī)構(gòu)和可調(diào)距螺旋槳。利用低速柴油機(jī)驅(qū)動(dòng)的商船，通常只有一臺(tái)直接連到定距槳上的大型主機(jī)。 Medium speed, four –stroke diesel engines 中速四沖程柴油機(jī) Medium speed engines operate in speed ranges from 300 to 900 rpm. The majority of medium speed engines operate on the fourstroke cycle. 中速機(jī)的運(yùn)轉(zhuǎn)速度 范圍是 300 — 900 rpm，大多數(shù)的中速機(jī)都是 四沖程柴油機(jī)。 They are most mon as the propulsion engines in smaller ships, roro and passenger ships. They are used widely as the electrical power generation engines in most merchant cargo ships. 它們?cè)谛⌒痛?、滾裝船舶以及客船上應(yīng)用較多，在大多數(shù)的商用貨船上被廣泛用做 發(fā)電機(jī)的原動(dòng)機(jī)。 Fourstroke engines have more moving parts, are more plex and produce less power for equivalent weight pared to twostroke slow speed engines. Medium speed engines do, however, offer several advantages which make them attractive for marine applications. 四沖程柴油機(jī)有較多的運(yùn)動(dòng)部件，也更加復(fù)雜一些，跟二沖程低速柴油機(jī)相比相同的重量發(fā)出的功率較少。然而，中速柴油機(jī)也有一些導(dǎo)致它們?cè)诖鲜褂玫膬?yōu)點(diǎn)。 1. The engines are pactthey are not long or high, this allows them to fit in engine rooms with low head space such as those in roro ships. Fitted under the vehicle deck. 它們不長(zhǎng)也不高，機(jī)型緊湊，這就使它們適合安裝在空間較低的機(jī)艙當(dāng)中，比如在滾裝船上，它們就安裝在汽車甲板的下面。 2. Medium speed engines use less oil than slow speed 。 3. Recent developments have produced medium speed engines capable of burning low quality heavy fuel 4. Engines of considerable power, to 25,000kw and more, have been developed, allowing a large power system to be achieved with pact engines and engine room. This makes them suitable for passenger ship applications where the smaller the space provided for engines and machinery the more space is available for paying passengers. 25,000kw 甚至更大功率的中速機(jī)已經(jīng)被開發(fā)出來(lái)，這就使得能夠利用較小體積的柴油機(jī)和較小空間的機(jī)艙達(dá)到較大的功率。這樣就適合在客船上安裝使用中速機(jī)，柴油機(jī)和機(jī)械設(shè)備占用的空間較小，能夠?yàn)槁每吞峁┏龈嗟目捎每臻g。 Most mediumspeed diesel engines are non–reversible meaning that a controllable pitch propeller is usually employed to cater for astern thrust. 大多數(shù)的中速柴油機(jī)是 不可倒轉(zhuǎn)的，這就意味著通常要利用變距槳實(shí)現(xiàn)向后的推力。 Propulsion system pared to an equivalent ship with a matched slow speed propulsion system operating at optimum conditions, when used as the primary source of power for propulsion applications mediumspeed engines can be used in a number of configurations. 對(duì)于同樣的船舶，相比于配備低速推進(jìn)系統(tǒng)，配備中速推進(jìn)系統(tǒng)的情況下，動(dòng)力裝置能始終工作于最佳工況。當(dāng)用作船舶推進(jìn)系統(tǒng)主要?jiǎng)恿υ磿r(shí)，中速機(jī)可以應(yīng)用在各種結(jié)構(gòu)的船型上。 Single propulsion engine 單主機(jī)推進(jìn) A ship‘s propeller operates most efficiently at low rotational speed especially in the case of the large diameter propellers used in cargo ships. 船舶螺旋槳在低轉(zhuǎn)速運(yùn)行時(shí)具有最高的效率，特別是當(dāng)大直徑的螺旋槳安裝在貨船上的時(shí)候更是這樣。 The slow speed twostroke engine can be directly coupled to the propeller as the maximum efficiency of each can be matched at a suitable rotational speed. 低速二沖程主機(jī)可以直接連接到螺旋槳 上，如果以合適的轉(zhuǎn)速匹配，主機(jī)和螺旋槳都能達(dá)到最高的效率。 In the case of the medium speed engine the output speed of the engine must be reduced to one more suitable for the propeller. 在使用中速機(jī)的情況下，主機(jī)輸出的速度必須要降到適合螺旋槳工作的轉(zhuǎn)速。 This is done using a reduction gearbox. To reduce the load on the engine during starting it is necessary to uncouple the propeller shaft from the drive shaft. This is done via a clutch which is often incorporated as part of the gearbox. The output shaft of gearbox then drives the controllable pitch propeller. 這通過(guò)變速齒輪想來(lái) 實(shí)現(xiàn)。為了在啟動(dòng)時(shí)降低主機(jī)負(fù)荷，有必要通過(guò)脫開驅(qū)動(dòng)軸與螺旋槳軸的耦