【正文】 壓氣機并聯(lián)的掃氣風機。 Two stroke cycle engines can be turbocharged in the same way as four stroke cycle engines. In most cases a scavenge blower, mechanically driven, is retained to assist the turbocharger. 二沖程柴油機和四沖程柴油機的渦輪增壓方式相同。 Scavenge blowers may be reciprocating air pumps driven directly from the crankshaft or running gear, or roots blowers or centrifugal pressors driven indirectly from the crankshaft by chain drives or gearing. 掃氣風機可能是往復式空氣泵，由曲軸或運轉(zhuǎn)機構(gòu)間接驅(qū)動，也可能是魯式風機或離心風機，通過曲軸的鏈傳動或齒輪機構(gòu)間接驅(qū)動。 The loop scavenge engine is mechanically simpler than the other types but because one piston controls both inlet and exhaust ports, it is usually necessary to provide light, quickacting nonreturn valves in the inlet port to prevent backflow of exhaust gas before the cylinder has blown down to a pressure lower than that in the scavenge air 流掃氣柴油機比其它柴油機機械結(jié)構(gòu)簡單，但是因為一個活塞控制進排氣口，通常在氣缸自身排氣壓力低于進氣總管壓力之前，需要在進氣口布置一個重量輕，能夠快速動作的止回閥來阻止廢氣逆流。 In the two stroke engines described so far the scavenging is carried out from one end of the cylinder to the other. This is termed uniflow scavenging. 到目前為止描述的二沖程柴油機掃氣是從氣缸的一端流動到另一端實現(xiàn)，這種方式稱為直流掃氣。 The two most monly used are separate crankshafts geared together and side connecting rods for the upper piston operated from extra cranks formed on the single crankshaft. 最為常用的機構(gòu)是采用獨立的曲軸，上部活塞的連桿作用在一個曲軸的額外曲柄上。 The two pistons may have the same length of stroke or the piston controlling the exhaust ports may have a shorter stroke than the one controlling the inlet ports. 兩個活塞有相同的行程長度，或者控制排氣口的活塞比控制進氣口的活塞行程短。 Another form of two stroke cycle engines is known as the opposed piston type. In operation it is very similar to the type just described, the chief difference being that the exhaust gases leave the cylinder via ports controlled by the upper piston instead of through a 種結(jié)構(gòu)是對置活塞式柴油機。 Towards the end of this stroke the exhaust valve is opened allowing the exhaust gases to escape and the pressure in the cylinder fall below that of the air manifold. Shortly afterwards, as the inlet ports are opened by the downward moving piston, the scavenging air enters and displaces the remaining exhaust gas in preparation for the next 時，排氣閥打開，開始排氣，此時氣缸壓力降至進氣總管壓力以下。 As the piston rises it cuts off the inlet ports and the exhaust valve is arranged to close at the same time. Compression of the charge of air takes place and fuel is injected into the hot pressed air as top dead centre is approached. Combustion occurs and the piston is driven downwards on the expansion stroke. 隨著活塞上行，進氣口關(guān)閉，同時排氣閥也被關(guān)閉，開始對空氣進行壓縮。進氣總管的空氣壓力大于排氣總管 的壓力，這樣就可以清掃廢氣，讓氣缸充滿新鮮空氣。 One form has a valve in the cylinder head through which the exhaust gases leave the cylinder and ports around the lower part of the cylinder through which the air 在氣缸頭上安裝排氣閥，在氣缸下部加工一圈環(huán)繞的空氣進氣口。 The quantity of air provided by turbocharger is so great that the amount of fuel that can be burnt in each cylinder per cycle (and hence the power) is not limited on this account but by the temperature which the exhaust valves, cylinder heads and pistons can ，所以每個循環(huán)下氣缸的燒油量（輸出功率）是沒有界限的，但是會受到排氣閥，氣缸頭和活塞的 承受溫度限制。 In engines having a high boost pressure the air leaving the pressor is hot and it is beneficial and sometime, necessary to cool it as this assists in increasing the mass of air filling the cylinders and in keeping the internal parts of the engine cool. The air is cooled by passing it through an intercooler. 在高增壓柴油機中，離開壓氣機的高溫空氣對柴油機來說是有利的，但有時必需的冷卻有助于提高進入到氣缸的空氣量，有助于冷卻柴油機的內(nèi)部元件。 More usually, some of the energy present in the exhaust gas is utilized by passing it through a turbine which is directly coupled to a centrifugal pressor. The pressor and turbine together form a free running unit, separate from the engine, known as a ，讓其通過渦輪機，而渦輪機直接和離心式的壓氣機連接，這樣壓氣機和渦輪機組合成一個和柴油機分離開來的自由運轉(zhuǎn)機構(gòu)，這個裝置稱為渦輪增壓器。這個過程被稱為增壓。 The cylinder can be charged with a greater mass of air by supplying it under pressure. The air is pressurized in a pressor, sometimes termed a blower, and fed to the induction manifold of the engine. The process is called pressure charging or 入大量空氣。The time available for bustion in the diesel cycle is very short。 In the case of a naturally aspirated engine the amount of fuel that can be burnt is limited by the mass of air drawn into the cylinder during the induction stroke. 對于自然吸氣柴油機來說，參與燃燒的燃油量受到吸氣行程中吸入到氣缸空氣量的限制。 The power of any diesel engine is determined by the amount of fuel that can be burnt in each cylinder per cycle and the speed at which it can be run. 任何柴油機的功率都是通過每個循環(huán)噴入氣缸燃燒的燃油量和它的運轉(zhuǎn)速度決定。 As the piston reaches the bottom of the cylinder for the second time the exhaust valve is opened and during the upward and fourth stroke the hot spent gases are expelled through 內(nèi)的最低點，排氣閥被打開，熱的廢氣通過活塞上行從排氣閥被排出。 The pression raises the temperature of the air and as the piston reaches the end of this stroke, a controlled amount of fuel is injected into the cylinder in the form of a fine spray. 壓縮行程會升高空氣溫度，隨著活塞達到行程的終點，一定數(shù)量的燃油以霧化形式噴射到氣缸內(nèi)部。 During this stroke the inlet valve remains open and a charge of air is drawn into the cylinder. 在這個行程中，進氣閥始終開啟，同時增壓空氣被吸進氣缸 The piston then returns to the top of39。 LESSON 2 Working Principle Of Diesel Engines 柴油機工作原理 FOUR STROKE CYCLE DIESEL ENGINES四沖程柴油機 The events of each of the four stroke cycle diesel engine are suction, pression, expansion and ，壓縮，膨脹和排氣。前面提到用中速機發(fā)出的電能來推進船舶的系統(tǒng)，同樣適用于高速柴油機。 The acceptance of highspeed engines in ships has grown in recent years with the development of larger horsepower engines, this has been assisted by cooperation between traditional mediumand slowspeed engine manufacturers with highspeed engine manufacturers, these manufacturers have begun to produce engines capable of supplying power in ranges that formerly fell between those of mediumand high –speed engines. 在近些年隨著更大功率柴油機的發(fā)展，高速柴油機在船舶上的應(yīng)用得到了提高，這得利于傳統(tǒng)中低速柴油機生產(chǎn)廠與高速柴油機生產(chǎn)廠的合作，這些生產(chǎn)廠開始生產(chǎn)位