汽车发动机英语教程-

1、Lesson 1. Petrol and Diesel Engines汽油发动机机和柴油发动机The explosive mixture of the petrol engine is provided by a carburettor, but in the case of the diesel engine the supply is effected by an injection or jerk pump which forces a shot of fuel into each cylinder in turn according to the correct firing sequ

2、ence.翻译:汽油发动机由一个化油器输送可燃混合气体,而柴油发动机,由一个喷射泵或柱塞式燃油泵实现燃油供应,此泵根据正确的点火顺序把少量燃油依次压入每个汽缸。The pump is actuated from a camshaft and the amount injected for each power stroke is extremely small at maximum output, indeed it may be less than 0.1 cm2 , Moreover, this charge must be metered with great and constant

3、accuracy even while it is being variably controlled to regulate power from idling to maximum.It will be realised that efficient and economical running is largely dependent upon the fuel pump.翻译:通过凸轮轴驱动油泵。每个功率冲程的燃油喷射量在最大输出功率时是非常微小的,实际上,可能小于0.1 cm2。而且,此燃油量虽然从怠速到最大速度要进行不同的控制调节,但此燃油量必须非常精确和稳定地进行测量。人们认识到

4、有效和经济的运行主要依靠燃油泵Multi-cylinder engines are normally equipped with pumps in unit monobloc form incorporating a corresponding number of elements,having a common camshaft and control means but provided with individual adjustments for regulating their output and setting their timing .An equal quantity of

5、 fuel must be delivered by each element, which is calibrated separately to a predetermined rate of delivery.Timing of the start of injection in relation to engine crankshaft position must also be constant and equal on each element, the setting process is called phasing.Calibration and phasing are pr

6、ecision operations to be carried out only by skilled service mechanics who have the necessary specialised equipment.翻译:多汽缸发动机一般情况下装配整体式油泵,把相关的喷射单元组合成一体,共用凸轮轴和控制方式,但可单独调整以调节各自功率输出和设定各自的正时。每个喷射单元必须输送等量燃油,按照预定的输送比率分别校准。与发动机曲轴位置度相关的喷射开始时间在每个喷射单元也必须是恒定相等的。设定的过程被称为调整相位。校准和调整相位是精确的操作,只有熟练的服务机械师用必要的专用工具才能进行

7、,A very important detail is that injection must cease cleanly and abruptly at the end of the delivery period without any trace ofafter-dribble from the injector; otherwise carbon deposits quickly form on the nozzle tip and excessive smoke will appear in the exhaust.The required condition is ensured

8、by the special design of the pump delivery valves which provide for a very rapid collapse of pressure in the injector fuel pipes at the end of injection翻译:一个非常重要的细节是燃油喷射必须在燃油输送结束时干净且突然地停止,从喷射泵上不留下任何后渗漏的痕迹。否则,在喷嘴尖上很快形成积碳,排气管将冒浓烟。这种要求由专用(专门设计的输油泵输送气阀来保证,此气阀可以在喷射结束时快速终止喷射泵燃油管的压力。At an early stage in th

9、e evolution of the high-speed diesel a variable timing device was introduced in the pump drive coupling, taking the form of a helically splined coupling by means of which the angular relation between driving and driven shafts could be varied by manual or automatic control.This device has always been

10、 a feature of Gardner engines where it is coupled to the accelerator control.In some makes of engine the helically splined coupling is not used and the angular displacement of the shafts is effected by centrifugally actuated devices of the swinging link or inclined plane type.The fitting of variable

11、 timing devices has been discarded by some manufacturers in favour of fixed timing, but in recent years the extensive adoption of the distributor type of fuel pump, which incorporates a simple variable timing device, has now brought this refinement into much more general use.翻译:在高速柴油机发展的早期,可变的正时装置被引

12、用到油泵驱动联轴节上,采用螺旋式花键套管的形状,驱动轴和从动轴之间的相对角度可以通过手动或自动控制进行改变。此装置是加德纳发动机的一个特征,总是和加速器控制连接在一起。在一些发动机的制造中,并不使用螺旋式花键套管,通过摇杆或斜面型的偏心操纵装置,曲轴相位角起到同样作用.一些制造商放弃装配可变正时装置,而采用固定正时。但是,最近,装配一个简单可变正时器的分配器型的燃油泵广泛采用,使这精致的附件获得更普遍的使用。From the above it will be realised that fundamental difference between petrol and diesel engin

13、es is that in the petrol engine the source of heat for igniting the charge, namely an electric spark, is generated outside the engine, and is taken, as it were, into the waiting charge at the required instant.In the diesel engine the source of heat for igniting the charge is created within the engin

14、e by compressing pure air to a degree that will initiate combustion and then injecting the fuel at the right time in relation to the movement of the crankshaft.It will have been gathered that apart from their auxiliary features, both classes of engine are of very similar construction.But as the dies

15、el is called upon to withstand very much greater stresses due to higher pressures in the cylinders, it has to be of more substantial construction and is thus heavier.翻译:通过以上描述,人们认识到汽油机和柴油机之间的基本差别是汽油机里,点燃混合气体的(也就是一个电火花塞热源产生于发动机外面,在要求的瞬间,热源被吸进等待的混合气体里。在柴油机里,点燃燃料热源产生于发动机内部,把纯净的空气压缩到开始燃烧的程度,然后,在曲轴运动相连的准

16、确时刻喷射燃油。从收集的资料看,除了辅助的特点外,两种的发动机结构非常相似。但是。由于压力更高,柴油机的汽缸里要求经受大得多的应力,所以,柴油机必须(拥有更坚固的结构,因而,会增加起其重量。(其重量更重By careful design and by taking full advantage of the most advanced metallurgical technique the power/weight ratio of the automotive dieselwas substantially improved within the course of a very few y

17、ears so that the weights of present-day engines do not appear to be capable of much further reduction翻译:通过认真设计和完全利用最先进的冶金技术的优点,汽车柴油机的功率/重量比在最近几年里有本质的改进,以致,现在发动机的重量似乎已经降到最低程度(似乎不能再减少。Lesson 2. The Four-stroke Cycle四冲程循环Anyone familiar with the working of the ordinary petrol engine is aware that the m

18、otive power is produced by igniting above the piston in each cylinder a mixture of petrol vapour and air, the resultant combustion of which causes an expansion of gases exerting pressure on the top of the piston.By this means the heat released by the fuel is transformed into work, the reciprocating

19、movement of the pistons being converted into rotary movement of a crankshaft by means of the connecting rods翻译:熟悉普通汽油发动机原理的人知道,通过点燃每个汽缸里活塞上面汽油蒸气和空气混合气体,混合气体燃烧的结果使气体膨胀,给活塞顶部施加压力而产生动力。通过这种方式,燃料释放的热量被转换成功。活塞的往复运动通过连杆被转换成曲轴的旋转运动。The four-stroke cycle is the operating sequence more commonly employed.It r

20、equires that each cylinder be provided with an inlet valve to admit a combustible mixture of petrol and air drawn by the suction of the engine from a mixing device known as the carburettor into the space above the piston, while there must also be an exhaust valve to control the outlet through which

21、the residual products of combustion are ejected after they have done their work.四冲程循环是被普遍采用的工作顺序。四冲程循环要求装配一个进气阀,允许把发动机从混合装置也就是化油器上吸入的可燃的汽油和空气混合气体进入活塞上面的空间,同时,也必须有一个排气阀,控制排出气体,把燃烧的残余物质在做完功后喷射出去。To describe the complete cycle as it occurs in any one cylinder it may be assumed that the piston is at the

22、 top of the stroke and that both the inlet and the exhaust valves are closed.As the piston descends the inlet opens so that charge of mixture can flow into the cylinder. This is called the suction(or inductionstroke, the charge flowing under the influence of external atmospheric pressure.Immediately

23、 after the piston has reached its lowest position and begins to rise again the inlet valve is closed so that the mixture can be compressed by the rising of the piston on the compression stroke As the piston once again approaches its topmost position an electric spark is caused to pass between the po

24、ints of a sparking plug located in the top of the cylinder in a zone called the combustion chamber.The spark ignites the mixture and as both valves are closed during its combustion, there is a considerable pressure rise.As a result, the piston is forced back again down the cylinder, this movement be

25、ing termed the expansion or power stroke翻译:为了描述在任何一个汽缸里发生的完整的工作循环,可以假设活塞处于冲程的顶部,进气阀和排气阀关闭。随着活塞下降,进气阀打开,以便混合气体燃料能流进汽缸。这过程被称为进气冲程(或感应冲程,燃料受外部大气压力的影响流动。在活塞已经到达最地位置后,活塞立即再次上升,进气阀关闭,以便混合气体被上升的活塞压缩,称为压缩冲程。随着活塞上升到接近最高位置,一个电火花被打着,从火花塞的顶尖穿过,火花塞位于被称为燃烧室的区域的汽缸的顶部。火花点燃混合气体,随着两个气阀在燃烧时关闭,有巨大的压力上升。结果,活塞再次被压回汽缸,此运动

26、被称为膨胀冲程或动力冲程。Before the piston reaches its lowest point, the exhaust valve is opened, pressure is released, and as the piston again rises it sweeps the residual gas through the exhaust outlet, whence it is led through a silencer to the atmosphere; this is the exhaust stroke which completes the conti

27、nuously repeated cycle.Thus it will be seen that there is one power stroke for every four strokes of the piston or two revolutions of the crankshaft在活塞达到最低点时,排气阀打开,压力释放,随着活塞再次上升,活塞把残余气体压向排气出口,这里,排出气体经过一个消声器被导进大气;这是排气冲程,完成不断连续重复的循环。因而,可以看出活塞的每4个冲程或曲轴的两转有一个动力冲程。It should be noted that the size of the

28、combustion chamber above the piston (known as the clearance space is considerably smaller than that part of the cylinder in which the piston travels.Thus at the end of the compression stroke the explosive mixture is compressed to a pressure varying from about 5. 5 to 7kg/cm2(80 to 100 lbf/in2.By suc

29、h compression the mixture is heated to some extent, resulting in better vaporisation of the fuel, and more intimate mixing of the vapor and air; it also enables the engine to work with higher thermal efficiency, to which further reference is made later.应该注意活塞上面燃烧室的大小(被人称为间隙空间比汽缸里活塞行程的那部分相对要小一些。因而,在压

30、缩冲程结束时,混合可燃气体被压缩到大约5.5-7 kg/cm2 (80 - 100 lbf/in2的压力。通过这种压缩,混合气体被加热到一定程度,使燃料汽化更好,并使空气和燃料汽的混合更精细,这也使发动机以更高的热效率做功,后面文章会对热效率作进一步的解释。Incidentally, the ratio of the total volume of the cylinder above the piston when it is in its lowest position to that of the combustion or clearance space when it is at i

31、ts highest position is known as the compression ratio and in modern commercial vehicle petrol engines varies from about 6:1 to 8:1顺便提一下,活塞最低位置时汽缸的总容量和活塞最高位置汽缸燃烧时的容量或间隙空间的比率被称为压缩比。现代商用车的汽油发动机的压缩比范围从大约6:1到8:1。The operating cycle of the four-stroke diesel is identical in so far as the sequence of strok

32、es is concerned but there is a major difference in principle.On the induction stroke only pure air is drawn into the cylinder through the inlet valve port.Then, because the clearance space is so much smaller than that in a corresponding petrol engine, the compression ratio is considerably higher, be

33、ing not less than 12:1 and even in some engines as high as 21:1.The final pressure of the air charge at the end of the compression stroke may be 35kgf/cm2(500 1bf/in2or more, with a corresponding temperature rise to not less than 1000°F(538, which is sufficient to ignite finely atomized but non

34、-volatile fuel oil without the assistance of an electric spark.4冲程柴油机的工作循环就冲程顺序而言是相同的。但是原理上有一个重要的差别。在感应冲程,只有纯净的空气通过进气阀口吸进汽缸。那么,因为间隙空间比相应的汽油发动机的要小的多,其压缩比相当高,不低于12:1,甚至有些发动机达到21:1。压缩冲程结束时冲气的最终压力可能为35kgf/cm2(5001bf/in2或更高,随着相应的温度上升到至少1000°F(538,足以点燃精细雾化的但尚未挥发的燃油,无须电子火花塞的辅助。Just before the piston r

35、eaches the end of the compression stroke the fuel oil is injected into the combustion chamber through an injection nozzle, or sprayer, mounted on the cylinder head in much the same position as the sparking plug in a petrol engine.The pressure at which the fuel is injected must necessarily, of course

36、, be higher than the combustion pressure , usually not less than 140kgf/cm2(2000 1bf/in2.During injection the fuel is split up into finely divided particles, and the mixture of these with the air forms an explosive charge that is ignited by the heat of compression.在活塞到达压缩冲程结束前,燃油通过一个喷射喷嘴或喷雾器被喷射入燃烧室,

37、喷嘴或喷雾器安装在缸盖上,和汽油发动机上火花塞的位置完全相同。燃油喷射的压力当然且必须比燃烧压力高,通常至少达到140 公斤力/平方厘米kgf/cm2 (2000 磅力/平方英寸 1bf/in2喷射时,燃油被碎成微小颗粒,这些颗粒和空气的混合体形成爆炸(可燃气体,被压缩的热量点燃。Injection is continued for a short period, during which the piston passes its highest position and begins to descend on the power stroke.The expansion of combu

38、stion products only begins to have effect when the piston has passed the top of its stroke, and during the injection period the burning fuel maintains a more or less constant pressure somewhat above that of compression; When the fuel is cut off expansion of the gases continues, the pressure is falli

39、ng as the piston descends.The overall effect on the piston is a more sustained pressure than that associated with the combustion process in a petrol engine.The effective part of the power stroke is concluded before the piston descends to its lowest point, and the cycle is completed when the exhauste

40、d gases are expelled by the rising piston.喷射持续很短的时间,此时活塞经过最高位置,开始下降到动力冲程。当活塞已经通过压缩冲程的顶部时,燃烧物的膨胀才开始起作用,喷射期间,燃烧的燃油保持较稳定的压力,稍微高于压缩压力;当燃油被切断,气体继续膨胀,压力随活塞的下降而下降。对活塞的总的作用是与汽油发动机里和燃烧过程相关的压力相比具有一个更稳定的压力动力冲程的有效部分在活塞下降到最低点前结束,当废气被上升的活塞排出时,循环完成。To inject the fuel a special type of pump driven by the engine is

41、employed, and this is a distinguishing feature of the diesel engine, just as the carburettor and the magneto or coil and distributor ignition apparatus distinguish the normal petrol engine.燃油的喷射靠使用一个由发动机带动的专用型式的泵来实现的。这是柴油发动机一个明显的特征。而化油器、磁发电机或线圈和分配器点燃装置显示出正常的汽油发动机的特点Lesson 3. Horsepower马力AN engine pr

42、oduces power only when a load is applied.When the engine first starts, the load applied is in the form of its own friction and compression.The resistance offered by various accessories also affects this initial load .an engine must drive a fan, generator, injection pump, water pump, perhaps a compre

43、ssor too.All of these add to the load on an engine before you apply that toad at the output shaftWeve s aid that an engine produces power when a load is applied.What, exactly, is power? Power is the capacity of an engine to do work.WOEK is defined as moving an applied force through distance.POWER is

44、 work with the element of time added or how long it took to do the work.HORSEPOWER is the measure of power.One horsepower is a measurement of the force required to lift 33, 000 lbs a distance of one foot in one minute.只有给发动机增加负载时,发动机才发出功率。发动机第一次启动时,增加的负载是自我摩擦和压缩。各种附件施加的阻力也影响这初始的负载.发动机必须带动风扇,发电机,喷射泵,

45、水泵,或许也带动一台压缩机。在你把负载加到输出轴上之前,所有这些阻力都加在发动机的负载上。我们曾说只有给发动机增加负载时,发动机才发出功率。准确的说,什么是功率?功率是一台发动机做功的能力。做功被定义为把一个作用力移动一定的距离。功率是单位时间内所做的功或花多长时间的做功。马力是功率的单位。一马力等于在一分钟时间内提起33, 000磅的重量通过一英尺的距离所要求的力的大小。提起33, 000磅的重量在一分钟时间内通过一英尺的距离时功率的计量单位Horsepower shows up in engine rating specs under several names .It may be li

46、sted on these specs as maximum, intermittent, continuous or gross horsepower.How do these terms differ.马力在发动机标定值规格表中有不同的名称。在标定值规格表中可能列为最大马力,间隙马力,连续马力或总马力这些术语有什么不同呢?Gross horsepower is a measure of the power units , produced by a bare engine, with no power drain caused by accessories.Manufacturers of

47、ten use this measure to establish a base line when setting up engine ratings because this method eliminates the variables imposed by different accessories, which may or may not be used on that particular engine in actual service.总马力是一台没有附件功率消耗的裸机的功率单位,制造商在设定发动机额定功率时经常使用此单位确定基准线。本方法可以消除不同附件产生的影响,在某一特

48、定发动机的实际运用中,这些附件可能使用,可能不使用。Net or flywheel horsepower represents the power units produced by afully-equipped engine at the output shaft or flywheel.净功率或飞轮马力是功率单位,表示一台完全装配的发动机在输出轴或飞轮轴上输出的功率Brake horsepower is another term you may come across while puzzling over an engine rating chart.This simply means

49、 the power, available at the output shaft for doing work and is the same as net horsepower .The term is a hold-over from the days when the brake horsepower was actually measured on a form of a brake device called a Prony brake.Today a dynamometer is the instrument most often used and now you know wh

50、y some people still can a dynamometer a brakePerformance curves can be confusing.Knowing what each curve represents can do much to eliminate this confusionMaximum brake horsepower curve is the curve showing the highest horsepower that an engine will develop at any rpm within its range.Normally this

51、curve is used for engines which must produce peak power for short periods of time or for special applications.制动马力是你在研究发动机额定功率值图表时会碰到的另一个专业术语。简单的说,它就是做功时输出轴能提供的功率,而且等同于净功率。此术语是从过去沿用下来的,当时制动马力在实际运用中用一个被称作普龙尼制动闸的制动装置进行测量。今天,测功机是最常用的设备,现在你知道为什么一些人仍然把测功机称为制动闸(刹车。性能曲线使人困惑。如果知道每条曲线代表的意思会非常有助于消除这种困惑。最大制动马力

52、曲线(极限外特性曲线是表示一台发动机在允许的每分钟转速范围内发出的最高马力曲线。正常情况下,此曲线用于发动机在短时间内或特殊用途中必须发出最高功率Intermittent brake horsepower curve is normally about 90% of the maximum and is the horsepower curve recommended or satisfactory operations under certain conditions of load and speed,usually variable load and speed conditions w

53、here top load and speed are only needed for short periods.“Intermittent” curves are the ones most often used for vehicular applications.间隙制动马力曲线(瞬时外特性曲线通常大约是最大马力的90%,是在某负荷和速度条件下进行良好运行而推荐的马力曲线,通常此条件是变化的负荷和速度条件,最大负荷和最高速度只在很短的时间内需要,间隙曲线是汽车运用中最常用的曲线。Continuous brake horsepower curves are about 80% of ma

54、ximum and are the curves recommended for satisfactory continuous operation.A generator set is an example of an application in which the continuous brake horsepower curve might be usedDrawbar horsepower is a term commonly found in tractor engine ratings and is a measurement of the power developed at

55、the tractors drawbar, Drawbar horsepower is found by measuring the horizontal drawbar pull and the exact tractor traveling speed持续制动马力曲线大约是最大马力的80%,是进行持续良好的运行而推荐的曲线,发电机组是使用持续制动马力曲线的一个实例。牵引马力是一个拖拉机发动机额定功率值里都能找到的一个专业术语,是拖拉机牵引所发出的的功率的功率单位。牵引马力是通过测量水平牵引力和拖拉机实际行驶速度所求的。A unit of power in the U.S. Customar

56、y System, equal to 745.7 watts or 33,000 foot-pounds per minute.马力美国习惯体系中的功率单位,相当于745.7瓦特或33,000英尺-磅/分The power exerted by a horse in pulling.一匹马在拉东西时使用的力量4.Torque and Fuel Consumption力矩和燃油消耗The moment of a force;the measure of a force's tendency to produce torsion and rotation about an axis, eq

57、ual to the vector product of the radius vector from the axis of rotation to the point of application of the force.转矩,力矩一种测量产生扭转和绕轴旋转趋势的力的单位,等于从旋转轴到力作用点的旋转矢量Weve already said that horsepower is a measure of an engines ability to produce power.Theres another term you should understand which influences

58、 an engines ability.Independent of horsepower, to do a specific job.This is torque.我们曾说马力是一台发动机产生动力的能力的测量单位。你应该了解另一个影响发动机做具体工作的能力、与马力无关的专业术语。这就是力矩。Torque. When a force is applied at right angles to a radius of a wheel or to the end of a lever, it creates a twisting force called torque.Torque is measured in pound/in. or pound-ft.力矩.当一个作用力与轮子的半径或与杠杆的一端成直角时,他产生一个旋转力,被称为力矩。力矩用磅/英寸或磅-英尺作为测量单位If a force of 50 1bs is applied to a 6-in crank, torque created in the crankshaft would be 50x6=300 1b-in.Or 50x0.5(6 in.=0.5ft=25 1b-ft.If the c