LESSON 1 Diesel engines
The majority of ships around the world continue to be powered exclusively by diesel engines. 世界范围内大多数船舶都是采用柴油机作为动力。
The predominance of diesel engines has come from improved engine efficiencies and designs compared to other forms of propulsion such as steam or gas turbines.
与蒸汽机、燃气轮机等形式的动力装置相比，无论是效率上的提高，还是设计上的进步，柴油机都体现出了一定的优势。
Many combinations and configurations of diesel engine power plant exist. All provide the energy to do the work of moving the ship using diesel engines.
存在有很多种联合形式及结构形式的柴油机动力装置，他们都能够利用柴油机为船舶提供推动力。
Slow speed diesel engines 低速柴油机
Slow speed diesel engines are large, especially tall, and heavy and operate on the two-stroke cycle.
低速柴油机是体积较大、缸体较长、机身较重的二冲程柴油机。
These are the largest diesel engines ever built. Engine powers up to 100 000kw are available from a single engine.
它们是已建造过的最大型的柴油机，它们的单机可用功率可达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.
较长的缸体能提供一个较长的冲程，有助于提高柴油机的效率。
The large physical size of the engine and components leads to slow rotational speed with speeds up to 300rpm considered to be slow.
柴油机及其部件的物理体积较大，导致其回转速度较低，尽管能够加速到300 rpm，但还是被认为是低速机。
For equivalent power output, the two-stroke diesel engine is significantly lighter than its comparable four-stroke relative.
对于相同的功率输出，相对于四冲程柴油机，二冲程柴油机的重量明显轻很多。
This is most apparent for large power requirements where the two-stroke engine produces much more power for the same weight.
对于大功率需求场合这是一个最明显的优势，二冲程柴油机能够在相同的重量情况下，发出更大的功率。
Large, slow speed, two-stroke marine diesel engines offer the advantages of： 大型、低速、二冲程船用柴油机的优点如下：
1. Burning poorer quality, cheaper fuel 燃烧劣质、低价的燃油
2. Providing large power from a single, less complicated machine comprising fewer individual
cylinders and moving parts一个仅有几个独立汽缸和运动部件组成的、低复杂程度的柴油机就能提供较大的功率。
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, 回转速度较低，能够直接和螺旋桨连接，不需要像离合器、齿轮箱等的中间传动机构。
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.
因为能够倒转，所以就不需要换向机构和可调距螺旋桨。利用低速柴油机驱动的商船，通常只有一台直接连到定距桨上的大型主机。
Medium speed, four –stroke diesel engines 中速四冲程柴油机
Medium speed engines operate in speed ranges from 300 to 900 rpm. The majority of medium speed engines operate on the four-stroke cycle.
中速机的运转速度范围是300 —900 rpm，大多数的中速机都是四冲程柴油机。
They are most common as the propulsion engines in smaller ships, ro-ro and passenger ships. They are used widely as the electrical power generation engines in most merchant cargo ships.
它们在小型船舶、滚装船舶以及客船上应用较多，在大多数的商用货船上被广泛用做发电机的原动机。
Four-stroke engines have more moving parts, are more complex and produce less power for equivalent weight compared to two-stroke slow speed engines. Medium speed engines do, however, offer several advantages which make them attractive for marine applications.
四冲程柴油机有较多的运动部件，也更加复杂一些，跟二冲程低速柴油机相比相同的重量发出的功率较少。然而，中速柴油机也有一些导致它们在船上使用的优点。
1. The engines are compact----they are not long or high, this allows them to fit in engine rooms
with low head space such as those in ro-ro ships. Fitted under the vehicle deck. 它们不长也不高，机型紧凑，这就使它们适合安装在空间较低的机舱当中，比如在滚装船上，它们就安装在汽车甲板的下面。
2. Medium speed engines use less oil than slow speed engines.中速机比低速机更省油。
3. Recent developments have produced medium speed engines capable of burning low quality
heavy fuel oil.近年来的发展也使中速机能够燃用低质燃料油
4. Engines of considerable power, to 25,000kw and more, have been developed, allowing a
large power system to be achieved with compact 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机已经被开发出来，这就使得能够利用较小体积的柴油机和较小空间的机舱达到较大的功率。这样就适合在客船上安装使用中速机，柴油机和机械设备占用的空间较小，能够为旅客提供出更多的可用空间。
Most medium-speed diesel engines are non–reversible meaning that a controllable pitch propeller is usually employed to cater for astern thrust.
大多数的中速柴油机是不可倒转的，这就意味着通常要利用变距桨实现向后的推力。
Propulsion system compared 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 medium-speed engines can be used in a number of configurations.
对于同样的船舶，相比于配备低速推进系统，配备中速推进系统的情况下，动力装置能始终工作于最佳工况。当用作船舶推进系统主要动力源时，中速机可以应用在各种结构的船型上。
Single propulsion engine 单主机推进
A ship‘s propeller operates most efficiently at low rotational speed especially in the case of the large diameter propellers used in cargo ships.
船舶螺旋桨在低转速运行时具有最高的效率，特别是当大直径的螺旋桨安装在货船上的时候更是这样。
The slow speed two-stroke engine can be directly coupled to the propeller as the maximum efficiency of each can be matched at a suitable rotational speed.
低速二冲程主机可以直接连接到螺旋桨上，如果以合适的转速匹配，主机和螺旋桨都能达到最高的效率。
In the case of the medium speed engine the output speed of the engine must be reduced to one more suitable for the propeller.
在使用中速机的情况下，主机输出的速度必须要降到适合螺旋桨工作的转速。
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.
这通过变速齿轮想来实现。为了在启动时降低主机负荷，有必要通过脱开驱动轴与螺旋桨轴的耦合。这可以通过减速齿轮箱内部的离合器组件来实现。齿轮箱的输出轴驱动可调距螺旋桨。
The output shaft of the engine is coupled to the gearbox. The output shaft of the gearbox drives the CPP through a clutch arrangement.
主机的输出轴连接到齿轮箱上，齿轮箱的输出轴通过离合器机构驱动可调距螺旋桨 The oil supply to and from the propeller is fed into the propeller shaft through an oil distribution box. This box is attached to a collar running on a section of the propeller shafting, thrust forces maybe accommodated in a separate thrust block and bearing.
供给螺旋桨以及从螺旋桨返回的油，是通过一个油液分配箱供给到螺旋桨轴内部。这个分配箱安装在螺旋桨轴上的一个连续的凸肩上，推力可以通过独立的推力块和推力轴承传递。
Many gearbox designs incorporate the clutch, thrust bearings and CPP oil distribution box into the same casing as the reduction gears, this design has the following advantages.
许多减速齿轮箱在设计时，将离合器、推力轴承和可调距螺旋桨的油液分配箱与减速齿轮一起整合在齿轮箱内部。这样设计有如下的优点：
1. The engine transmission package uses components that are known to be compatible and have
been proven to work together reliably. 使用各组成部件一起工作的主机传动系统，各部件能协调运转并且工作可靠。
2. The cost and complexity of installation is less than if separate, standalone components were
to be used. 与各部分单独使用相比，这种整合在一起的装置费用和复杂程度都较低。 3. The entire installation is smaller in size, especially length, than the separate units.整个装置
尺寸较小，尤其是长度比分开布置的单元小很多。
4. Negotiations and correspondence etc are simplified as only one supplier need be dealt with.
因为只需要跟一个供应商联系，所以商谈以及联系等也简化了。 Multiple propulsion engines 多主机推动
Larger vessels and ships using medium-speed engines usually use two or more engines to provide power to the propeller. Multiple engine installations can have several configurations. The first two arrangements discussed in this section have engines driving a propeller through a transmission gearing system. Other propulsion arrangements using multiple engines are possible. A number of these possibilities are discussed later in the section.
使用中速机的大型船舶通常使用两台或者更多的主机来给螺旋桨提供动力，安装多台主机可以有多种的布置方式。两种布置方式将在这一段进行讨论，第一，所有主机通过一个传动机构驱动螺旋桨。第二，使用多台主机的推进布置方式也是可能的。一系列的可能性在这一段的后半部分讨论。
Single propeller shaft with geared drive 单轴驱动
Multiple engines can be arranged to drive a single propeller. This is usually done by using a multiple input reduction gear. All the engines are arranged around the gearbox, each engine is connected to the gearbox through a clutch allowing multiple stages of power output to the propeller. A single output from the gearbox drives the propeller through a thrust bearing and CPP oil distribution collar, if fitted.
多台主机驱动一个螺旋桨轴，通常是通过多台主机向一个减速齿轮箱输入动力，所有这些主机围绕着减速齿轮箱布置，每一台主机都通过一个离合器与齿轮箱相连，输出到螺旋桨上的功率可以多级调节，齿轮箱的唯一输出端通过推力轴承、可调距桨油液分配箱凸肩（如果安装）驱动螺旋桨。
Multiple propeller shafts 多轴驱动
Some vessels are propelled by more than one propeller, for example some ferries, passenger ships, special purpose ships, offshore vessels and ro-ro vessels etc. The majority of multiple propeller applications are smaller vessels requiring added manoeuvrability. This is not always the case as some very large ships have been built with two propellers. These large ships have had two propellers directly coupled to slow speed engines. This effectively produces a ship with two engine rooms, one for each engine. In smaller vessels the engine configurations are usually extensions of the single or multiple engines, single shaft arrangements mentioned above. Medium-or high–speed engines are usually used in these cases. In vessels such as catamarans with propeller drives ，one drive system is mounted on each of the hulls. This creates two engine rooms. Two examples, the first of a catamaran, the second a twin screw ship.
有一些船平行布置多个螺旋桨，例如，一些渡船、客船、特殊用途船、近海船和滚装船等。多螺旋桨形式主要用在机动性要求高的小型船上。非常大型的船不总是都配置双螺旋桨，如果配置的话，两个螺旋桨就直接连接到两台低速机上，这样一艘船就会有两个机舱，每个机舱放置一台主机。在一些较小的船上，发动机通常布置成一台或多台的形式，而输出则布置成前面提及的单轴形式，这种情况下通常会采用中速或高速机。螺旋桨驱动的双体船就是驱动系统分别安装在两个船体上，这样就会产生两个机舱，这是一个例子，另一个例子就是双螺旋桨的船。
High-speed diesel engines 高速柴油机
The most common diesel engine throughout the world is the high-speed engine. The majority of these engines operate on the four-stroke cycle but a significant proportion utilize the two-stroke cycle. These engines have running speeds over 1000rpm and are ideally suited to driving
land-based vehicles such as busses and trucks. the application of high-speed diesel engines as propulsion engines at sea id limited to smaller vessels such as tugs ,ferries and barges etc. they are regularly used for electrical power generation in support of a medium-speed propulsion engine, on larger ships their use is limited to emergency power generation to small applications such as diesel driven emergency pumps and compressors.
世界范围内最普通的柴油机是高速柴油机，高速柴油机大部分是四冲程柴油机，但也有一部分是二冲程机。高速机的转速高于1000rpm，比较适合驱动陆地上的车辆，比如公共汽车、卡车等。高速柴油机如果用作海上交通工具的推进器的话，也仅限于一些像拖船、渡船和驳船等小型船舶上。它们通常在中速机船上用作发电机的原动机，在大型船上他们仅用来给一些小型设备比如柴油机驱动的应急泵、空气压缩机等作为应急发电机用。
The acceptance of high-speed engines in ships has grown in recent years with the development of larger horsepower engines, this has been assisted by co-operation between traditional medium-and slow-speed engine manufacturers with high-speed engine manufacturers, these manufacturers have begun to produce engines capable of supplying power in ranges that formerly fell between those of medium-and high –speed engines.
在近些年随着更大功率柴油机的发展，高速柴油机在船舶上的应用得到了提高，这得利于传统中低速柴油机生产厂与高速柴油机生产厂的合作，这些生产厂开始生产位于中速机与高速机之间这些以前被遗漏的机型。
The propulsion layouts used with high-speed engines parallel those mentioned above for medium-speed engines.
The diesel-electric propulsion system described above for medium-speed engines is equally applicable to high-speed engines. The scale of system and applicability will be reduced. 推进系统的设计采用高速机平行布置，这种布置形式在前面中速机部分提过。前面提到用中速机发出的电能来推进船舶的系统，同样适用于高速柴油机。但是系统的标准和适用性都将降低。
LESSON 2
Working Principle Of Diesel Engines
柴油机工作原理
FOUR STROKE CYCLE DIESEL ENGINES四冲程柴油机
The events of each of the four stroke cycle diesel engine are suction, compression, expansion and exhaust.每个四冲程柴油机的行程包括吸气，压缩，膨胀和排气。 Starting with the piston at the top of the cylinder, the induction stroke is performed as the piston moves down. 吸气行程是通过位于气缸内最高点的活塞下行实现。During this stroke the inlet valve remains open and a charge of air is drawn into the cylinder. 在这个行程中，进气阀始终开启，同时增压空气被吸进气缸 The piston then returns to the top of' the cylinder whilst both inlet and exhaust valves remain closed and the charge of air is compressed. 然后进排气阀保持关闭，活塞返回在气缸内的最高点，增压空气被压缩。The compression 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. 压缩行程会升高空气温度，随着活塞达到行程的终点，一定数量的燃油以雾化形式喷射到气缸内部。On coming into contact with the hot air the fuel ignites causing a rapid rise in pressure which drives the piston downwards on the expansion stroke.通过与热空气的接