汽车专业英语_3_AUTOMOTIVE_LUBRICATION_SYSTEM课件

1、Chapter 3 AUTOMOTIVE LUBRICATION SYSTEMu 背景知识背景知识 发动机工作时，很多传动零件都是在发动机工作时，很多传动零件都是在很小的间隙很小的间隙下作高速相下作高速相对运动的，如对运动的，如曲轴主轴颈曲轴主轴颈与与主轴承主轴承，曲柄销曲柄销与与连杆轴承连杆轴承，凸轮轴凸轮轴颈与凸轮轴承颈与凸轮轴承，活塞、活塞环与气缸壁面活塞、活塞环与气缸壁面，配气机构各运动副配气机构各运动副及及传动齿轮副传动齿轮副等。尽管这些零件的工作表面都经过精细的加工，但等。尽管这些零件的工作表面都经过精细的加工，但放大来看这些表面却是凹凸不平的。放大来看这些表面却是凹凸不平的。若不

2、对这些表面进行润滑，它们之间将发生强烈的摩擦。金若不对这些表面进行润滑，它们之间将发生强烈的摩擦。金属表面之间的干摩擦不仅增加发动机的功率消耗，加速零件工作属表面之间的干摩擦不仅增加发动机的功率消耗，加速零件工作表面的磨损，而且还可能由于摩擦产生的热将零件工作表面烧损表面的磨损，而且还可能由于摩擦产生的热将零件工作表面烧损，致使发动机无法运转。，致使发动机无法运转。 Chapter 3 AUTOMOTIVE LUBRICATION SYSTEM润滑方式润滑方式 由于发动机传动件的工作条件不尽相同，因此，对负荷及相对由于发动机传动件的工作条件不尽相同，因此，对负荷及相对运动速度不同的传动件采用不

3、同的润滑方式。运动速度不同的传动件采用不同的润滑方式。 1)压力润滑压力润滑压力润滑是以一定的压力把机油供入摩擦表面的润滑方式。这种方压力润滑是以一定的压力把机油供入摩擦表面的润滑方式。这种方式主要用于主轴承、连杆轴承及凸轮轴承等负荷较大的摩擦表面式主要用于主轴承、连杆轴承及凸轮轴承等负荷较大的摩擦表面的润滑。的润滑。 2)飞溅润滑飞溅润滑利用发动机工作时运动件溅泼起来的油滴或油雾润滑摩擦表面的润利用发动机工作时运动件溅泼起来的油滴或油雾润滑摩擦表面的润滑方式，称飞溅润滑。该力式主要用来润滑负荷较轻的气缸壁面滑方式，称飞溅润滑。该力式主要用来润滑负荷较轻的气缸壁面和配气机构的凸轮、挺柱、气门杆

4、以及摇臂等零件的工作表面。和配气机构的凸轮、挺柱、气门杆以及摇臂等零件的工作表面。 3)润滑脂润滑润滑脂润滑通过润滑脂嘴定期加注润滑脂来润滑零什的工作表面，如水泵及发通过润滑脂嘴定期加注润滑脂来润滑零什的工作表面，如水泵及发电机轴承等。电机轴承等。 Chapter 3 AUTOMOTIVE LUBRICATION SYSTEM New Wordsresidual rzdu:ladj.剩余的，残留的剩余的，残留的varnish v:nin.清漆，积碳清漆，积碳buildupn.组合组合,集结集结,累积累积,形成形成adhesion dhi:nn.粘着，附着，粘连粘着，附着，粘连cleanser

5、klenzn.清洁剂清洁剂sludgesldn.油泥油泥grime gramn.污垢，尘垢，烟灰污垢，尘垢，烟灰clogklv.填塞，塞满填塞，塞满gummvt.粘合粘合troughtr:f,trfn.槽，水槽，饲料槽，水盆，任何槽形物槽，水槽，饲料槽，水盆，任何槽形物bafflebfln.阻板，隔板阻板，隔板sumpsmpn.油底壳油底壳crankcasekrkkeisn.曲轴箱曲轴箱 New Wordsporosityp:rsitin.多孔性多孔性,有孔性有孔性peripheryprfri:n.外围外围syntheticsinetikadj.合成的，人造的，综合的合成的，人造的，综合的Ad

6、ditiveditivn.添加剂；添加剂；adj.添加的，附加的，加法的添加的，附加的，加法的antiscuffn.磨损磨损overhaulvh:l,vh:lvt.彻底检查，大修彻底检查，大修neutralizenu:trlaz,nju:-vt.使无效，抵消，使中和使无效，抵消，使中和agitationdtenn.激动，兴奋，煽动，搅动激动，兴奋，煽动，搅动 PHRASES AND EXPRESSIONS start-up起（启）动起（启）动 engineblock发动机气缸体发动机气缸体 dry-sump干油底壳干油底壳 wet-sump湿油底壳湿油底壳Chapter 3 AUTOMOTIV

7、E LUBRICATION SYSTEM PHRASES AND EXPRESSIONSpickuptube机油吸油管机油吸油管filterscreen滤网滤网full-flowfilteringsystem全流式滤清器全流式滤清器pressure-reliefvalve安全阀，泄压阀安全阀，泄压阀bypassvalve旁通阀旁通阀geartypeoilpump齿轮式机油泵，齿轮泵齿轮式机油泵，齿轮泵jockeypulley张紧轮，导向轮张紧轮，导向轮corrosioninhibitor阻蚀剂，腐蚀抑制剂阻蚀剂，腐蚀抑制剂detergent-dispersant清洁分散剂清洁分散剂viscos

8、ityindex粘度指数粘度指数foaminhibitor泡沫抑制剂泡沫抑制剂Chapter 3 AUTOMOTIVE LUBRICATION SYSTEM Reducing friction to minimize wear and loss of power is the primary job a lubrication system must perform. Residual oil on engine parts also provides lubrication for engine start-up.3.1 Lubrication Principles译文：译文：减小摩擦，降低

9、磨损和动力损失是润滑系减小摩擦，降低磨损和动力损失是润滑系统必须完成的主要工作。发动机部件上的残油也统必须完成的主要工作。发动机部件上的残油也可为发动机起动提供润滑。可为发动机起动提供润滑。Chapter 3 AUTOMOTIVE LUBRICATION SYSTEMThe engine oil forms a seal between the pistons, rings, and cylinders. It also helps to cool en-gine parts. Without the cleaning action of the lubricating system, car

10、bon and varnish buildup would be excessive. The engine oil also absorbs the shock and dampens the noise of moving parts.译文：译文：发动机机油在活塞、活塞环和气缸间形成密封。发动机机油在活塞、活塞环和气缸间形成密封。它也有助于冷却发动机部件。如果没有润滑系统的清洁它也有助于冷却发动机部件。如果没有润滑系统的清洁作用，积碳会过量集结。机油还可减震和消弱（抑制）作用，积碳会过量集结。机油还可减震和消弱（抑制）运动部件噪声。运动部件噪声。How successful the lub

11、rication system is in performing all these functions depends on a number of factors and conditions. There must be an adequate supply of good-quality lubricant delivered to all moving engine parts under sufficient pressure to provide hydrodynamic lubrication for rotating parts and oil adhesion to sur

12、face subject to sliding friction.译文：译文：润滑系统在执行这些功能时的成功程度由许多因润滑系统在执行这些功能时的成功程度由许多因素和条件所决定。充足的优质润滑油在压力作用下输送素和条件所决定。充足的优质润滑油在压力作用下输送到各运动发动机部件，以此来为所有转动部件提供流体到各运动发动机部件，以此来为所有转动部件提供流体动力润滑，机油附着在滑动摩擦的部件表面。动力润滑，机油附着在滑动摩擦的部件表面。3.2.1 oil pan The oil pan bolts under the engine block, where it seals off the bott

13、om of engine. Shaped like a trough, this sheet-metal pan serves as the reservoir for about 5 quarts of oil. As oil flows from the engine, it drains downward into the oil pan. 3.2 Parts of the Pressure-Lubrication Systemes译文：译文：油底壳用螺栓固定在发动机气缸体下方，油底壳用螺栓固定在发动机气缸体下方，封闭发动机的底部。它的形状像一个沟槽，由薄封闭发动机的底部。它的形状像一个

14、沟槽，由薄钢板制成，可储存大约钢板制成，可储存大约5 5夸脱的机油。当机油从发夸脱的机油。当机油从发动机流出时，它将向下排入到油底壳中动机流出时，它将向下排入到油底壳中。Chapter 3 AUTOMOTIVE LUBRICATION SYSTEMThe oil pump sucks oil from the lowest part of the oil pan, the oil sump. Many oil pans have baffles, which are thin metal partitions. These keep the oil in the sump when the c

15、ar corners hard or brakes suddenly. A drain plug at the bottom of the sump allows oil to be drained from the engine. The oil-pan gasket fits between the oil pan and the bottom of the engine block.译文：译文：油泵从油底壳的最低处抽油。许多油底壳带有薄油泵从油底壳的最低处抽油。许多油底壳带有薄金属隔板。它们可在汽车急转弯或突然刹车时将机油保金属隔板。它们可在汽车急转弯或突然刹车时将机油保持在油底壳中。放

16、油塞位于油底壳底部，可通过它将机持在油底壳中。放油塞位于油底壳底部，可通过它将机油从发动机排出。油底壳衬垫装在油底壳和气缸体底端油从发动机排出。油底壳衬垫装在油底壳和气缸体底端之间。之间。In most engines, the oil circulates in the engine, and then returns to the pan. It stays in the pan until drawn back into the engine by the oil pump. During operation, the sump usually holds 2 to 3 quarts o

17、f oil. The rest of the oil moves through the passageways of the lubrication system. 译文：译文：在大多数发动机上，机油在发动机内循环后要回在大多数发动机上，机油在发动机内循环后要回到油底壳中。然后一直在那里存放，直到被油泵抽回到到油底壳中。然后一直在那里存放，直到被油泵抽回到发动机。在这个运行过程中，油底壳只有发动机。在这个运行过程中，油底壳只有2 23 3夸脱机夸脱机油，其余的润滑系统通道内流动。油，其余的润滑系统通道内流动。With the engine off, the pan holds about f

18、our quarts of oil. The fifth quart is in the oil filter. Because a pool of oil always rests in the sump, the type of lubrication system is called a wet-sump oiling sys-tem.译文：译文：发动机熄火（停转）时，油底壳有发动机熄火（停转）时，油底壳有4 4夸脱机油夸脱机油，另外一夸脱的机油留在机油滤清器里。因为机油一直，另外一夸脱的机油留在机油滤清器里。因为机油一直保持在油底壳中，所以这种类型的润滑系统也称为湿式保持在油底壳中，所

19、以这种类型的润滑系统也称为湿式油底壳润滑系统。油底壳润滑系统。A dry-sump oil system is used in many racing engines. This system has a separate storage tank for the oil. A second oil pump draws oil from the oil pan as soon as the oil drains from the engine. As a result, a dry-sump system can circulate more oil through the engine t

20、han a wet-sump system.译文：译文：干式油底壳润滑系统在许多赛车发动机中采用。干式油底壳润滑系统在许多赛车发动机中采用。这个系统有单独的存储油箱。只要机油从发动机排出，就这个系统有单独的存储油箱。只要机油从发动机排出，就立即被第二个油泵从油底壳中抽出。因此，干式油底壳系立即被第二个油泵从油底壳中抽出。因此，干式油底壳系统要比湿式油底壳系统在发动机循环更多的机油。统要比湿式油底壳系统在发动机循环更多的机油。3.2.2 Oil Pump In most cars, the oil pump is in the crankcase above the sump. It draws

21、 oil through a tube that extends downward into the sump. This tube, called the oil-pump pickup tube, has a filter screen over its bottom end. The screen keeps large pieces of sludge and dirt from being drawn into the pump. 译文：译文：在多数汽车上，油泵位于油底壳上方的曲在多数汽车上，油泵位于油底壳上方的曲轴箱中。它通过延伸到油底壳中的油管把机油抽轴箱中。它通过延伸到油底壳中

22、的油管把机油抽出。这个管称为油泵吸油管，在它的底端带有一出。这个管称为油泵吸油管，在它的底端带有一个滤网。滤网可防止将大块的油泥和污垢抽到油个滤网。滤网可防止将大块的油泥和污垢抽到油泵中。泵中。The tube may be hinged on the pump end so that it can move up and down as the oil level changes in the sump. Thus, the pump always draws oil from the top of the sump, not from the bot-tom where the dirt

23、and sludge tend to settle. Modern cars use one of two common types of oil pumpsthe gear-type and rotor-type.译文：译文：吸油管用铰链接合在油泵末端，以便它能吸油管用铰链接合在油泵末端，以便它能够随油底壳内的油面变化而上下浮动。因此，油够随油底壳内的油面变化而上下浮动。因此，油泵是从油底壳上面抽油，而不是从其底部油泥和泵是从油底壳上面抽油，而不是从其底部油泥和污垢沉积的地方抽油。油泵有两种类型，污垢沉积的地方抽油。油泵有两种类型，齿轮式齿轮式和转子式和转子式。现代汽车一般可采用其中的一种。

24、现代汽车一般可采用其中的一种。3.2.3 Oil Filters A modern engine uses a full-flow filtering system (Figure 3-1) . In this system, the output of the oil pump flows through the oil filter before moving through the engine. In other words, the oil is filtered and cleaned before each trip through the engine. 译文：译文：现代汽车采

25、用全流式过滤系统。在这个系现代汽车采用全流式过滤系统。在这个系统中，油泵输出机油要先流过机油滤清器，然后统中，油泵输出机油要先流过机油滤清器，然后才穿过发动机。换句话说，机油在到达发动机各才穿过发动机。换句话说，机油在到达发动机各处之前被过滤和净化。处之前被过滤和净化。When an engine runs at 3,000 rpm, its entire five quarts of oil pass through the filter at least once every minute. Thus the oil filter ensures that only clean oil e

26、nters the engine.译文：译文：当发动机转速在当发动机转速在3000rpm3000rpm时，时，5 5夸脱机油夸脱机油每分钟至少穿过滤清器一次。因而机油滤清器可每分钟至少穿过滤清器一次。因而机油滤清器可确保只有洁净的机油才能进入发动机。确保只有洁净的机油才能进入发动机。Modern engines use replaceable oil filters. When dirty, such a screw-on filter is replaced with a new one. Inside the steel outer casing of the unit, a specia

27、l paper acts as a filter. Folded and tightly packed, this paper has just the right porosity. These tiny holes in the paper allow oil to pass through, but filter out dirt and sludge. The paper is treated to protect it from acid or water in the oil.译文：译文：现代发动机使用可更换的机油滤清器。现代发动机使用可更换的机油滤清器。当它布满污垢时，这种螺纹连

28、接滤清器就可被换当它布满污垢时，这种螺纹连接滤清器就可被换成新的。在滤清器的铁外壳内有一层特殊的纸作成新的。在滤清器的铁外壳内有一层特殊的纸作为滤芯。这种纸在被折叠和紧密压缩后，就具有为滤芯。这种纸在被折叠和紧密压缩后，就具有了多孔性。纸上的这些小孔能够滤除机油中的油了多孔性。纸上的这些小孔能够滤除机油中的油泥和污垢。这种纸经过（酚醛树脂）处理后，在泥和污垢。这种纸经过（酚醛树脂）处理后，在油中具有抗酸性和抗水湿性。油中具有抗酸性和抗水湿性。Normally, oil enters the oil filter from the outside. Oil enters the filter a

29、round the outer edge of the base. The oil flows through the paper to the center of the container. It then flows out to the en-gine. Most filters also have a pressure-relief valve, or bypass valve. Such a valve allows oil to flow to the engine without going through the filter. 译文：译文：通常，机油是从外面进入机油滤清器。

30、通常，机油是从外面进入机油滤清器。绕底座外围进入滤清器。机油流过纸滤芯到达容绕底座外围进入滤清器。机油流过纸滤芯到达容器中心，然后流出到发动机。大部分滤清器还带器中心，然后流出到发动机。大部分滤清器还带有一个卸压阀，或称为旁通阀。它可使机油直接有一个卸压阀，或称为旁通阀。它可使机油直接流到发动机而不需要穿过滤清器。流到发动机而不需要穿过滤清器。This is necessary when the filter becomes too clogged for oil to pass through it. Thus, a plugged filter allows dirty oil to ci

31、rculate through the engine. To prevent this, the oil and oil filter should be changed regularity.译文：译文：这在滤清器被严重堵塞，机油不能通过这在滤清器被严重堵塞，机油不能通过滤芯时是十分必要的。因而，被堵塞的滤清器会滤芯时是十分必要的。因而，被堵塞的滤清器会造成污油在发动机内循环。为了避免出现这种情造成污油在发动机内循环。为了避免出现这种情况，机油和机油滤清器应该定期更换。况，机油和机油滤清器应该定期更换。An internal combustion engine would not run f

32、or even a few minutes if the moving parts were allowed to make metal-to-metal contact. The heat generated due to the tremendous amounts of fric-tion would melt the metals, leading to the destruction of the engine. 3.3 Engine Lubrication译文：译文：如果允许运动部件之间金属接触，内燃机如果允许运动部件之间金属接触，内燃机运行不了几分钟。大量摩擦产生的热量会把金属运

33、行不了几分钟。大量摩擦产生的热量会把金属熔化，导致发动机的损坏。熔化，导致发动机的损坏。Chapter 3 AUTOMOTIVE LUBRICATION SYSTEMTo prevent this, all moving parts ride on a thin film of oil that is pumped between all the moving parts of the engine. Once be-tween the moving parts, the oil serves two purposes. One purpose is to lubricate the bear

34、ing sur-faces. 译文：译文：为防止这样，所有运动部件浮在一层薄为防止这样，所有运动部件浮在一层薄油膜上，这层油在发动机各个运动部件之间传送油膜上，这层油在发动机各个运动部件之间传送。运动部件之间的机油有两个作用，一是润滑轴。运动部件之间的机油有两个作用，一是润滑轴承面承面The other purpose is to cool the bearings by absorbing the friction-generated heat. The flow of oil to the moving parts is accomplished by the engines intern

35、al lubricating system. Figure 3-2 shows a engines lube oil circuit schematic.译文：译文：另一个是通过吸收摩擦产生的热量来冷另一个是通过吸收摩擦产生的热量来冷却轴承。（到达运动部件的）机油流动是由发动却轴承。（到达运动部件的）机油流动是由发动机的内部润滑系统来实现的。图机的内部润滑系统来实现的。图3 32 2是发动机的是发动机的润滑油路简图。润滑油路简图。The oil pump is of the gear type, consisting essentially of two gears in mesh and r

36、equires no at-tention or adjustment. It is housed in the sump, being driven by a shaft and skew gearing from the camshaft.译文：译文：齿轮式油泵主要由两个啮合齿轮构成，齿轮式油泵主要由两个啮合齿轮构成，不需要保养或调整。它放在油底壳中，由轴和凸不需要保养或调整。它放在油底壳中，由轴和凸轮轴的斜齿轮驱动。轮轴的斜齿轮驱动。Oil from the sump is delivered at full pressure to all main bearings and camsh

37、aft bearings through gallery pipes and drillings in the cylinder block. The big-end bearings are fed from the main bearings via passages in the crankshaft.译文：译文：油底壳机油通过气缸体中的油道和钻孔油底壳机油通过气缸体中的油道和钻孔全压传送到所有（曲轴）主轴承和凸轮轴轴承。全压传送到所有（曲轴）主轴承和凸轮轴轴承。（连杆）大端轴承润滑油由主轴承通过曲轴中的（连杆）大端轴承润滑油由主轴承通过曲轴中的油道提供。油道提供。Lubrication

38、 for the timing chain is supplied at two points; by a feed from the front camshaft bearing into the periphery of the camshaft chain wheel and also by oil fed through the hollow shaft on which the timing chain jockey pulley is mounted arid thence through holes in the circumference of the jockey pulle

39、y.译文：译文：正时链条的润滑由两路供给，一是从前正时链条的润滑由两路供给，一是从前凸轮轴轴承到其链轮外围。另一路是先通过正时凸轮轴轴承到其链轮外围。另一路是先通过正时链条导轮的空心轴，然后再通过导向轮轮周上的链条导轮的空心轴，然后再通过导向轮轮周上的孔。孔。The inlet (upper) and exhaust( lower) rocker shafts are hollow, the inlet shaft being fed with oil from the rear end of the main gallery pipe via an external pipeline, wh

40、ilst that for the exhaust rockers and inlet followers is supplied via drillings from the center camshaft bearings. 译文：译文：进气和排气摇臂轴是空心的，进气轴由进气和排气摇臂轴是空心的，进气轴由主轴承润滑油管后端通过一个外部管道供油，而主轴承润滑油管后端通过一个外部管道供油，而排气轴和进气轴从动件润滑油通过中心凸轮轴轴排气轴和进气轴从动件润滑油通过中心凸轮轴轴承钻孔提供。承钻孔提供。 Each rocker and follower receives its oil throug

41、h small holes drilled in the rocker shafts and in turn they are them-selves also drilled, so that the oil finds its way through them and thence out again to lubricate the points of contact with the valves, push-rods and camshaft. The distributor drive shaft is lubricated with oil fed from the exhaus

42、t rocker shaft via a hollow bolt.译文：译文：每个摇臂和挺杆从摇臂轴上所钻的小孔每个摇臂和挺杆从摇臂轴上所钻的小孔得到润滑油，然后机油进入它们本身带有的孔道得到润滑油，然后机油进入它们本身带有的孔道，从这些孔道出来后，再去润滑与之相连的气门，从这些孔道出来后，再去润滑与之相连的气门、推杆和凸轮轴。分电器传动轴由排气摇臂轴通、推杆和凸轮轴。分电器传动轴由排气摇臂轴通过一个空心螺栓供油。过一个空心螺栓供油。Surplus oil from the inlet valve gear returns through the cylinder casting and th

43、at from the ex-haust valve gear direct to the sump.译文：译文：来自进气门配气机构的残油通过气缸体来自进气门配气机构的残油通过气缸体回流，而回流，而排气门配气机构残油则直接落到油底壳排气门配气机构残油则直接落到油底壳中中。Motor oils for automobile engines fall into two basic categories: petroleum-based oils and synthetic oils. Petroleum- based oils, however, contain a variety of addi

44、tives; so in fact they, too, are partly synthetic . Some of the major additives include those described here .3.4 Lubrication Oils译文：译文：汽车发动机润滑油有两种类型：从石油汽车发动机润滑油有两种类型：从石油中提炼出的润滑油和合成润滑油。从石油中提炼中提炼出的润滑油和合成润滑油。从石油中提炼出的润滑油含有多种添加剂，因此，实际上也是出的润滑油含有多种添加剂，因此，实际上也是部分合成的。其主要的添加剂包括以下几点：部分合成的。其主要的添加剂包括以下几点：Chapte

45、r 3 AUTOMOTIVE LUBRICATION SYSTEMCorrosion inhibitors reduce the formation of harmful acids by attacking the acid-forming ingredi-ents. Combustion produces a number of by-products, including acids and water. Corrosion inhibitors neutralize these combustion by-products before they can do any harm to

46、the engine. A cold engine, rich fuel mixtures, a poorly tuned engine; and much short trip, cold-weather driving increases the amount of acids produced.译文：译文：防腐剂可通过破坏酸性成分来减少有害酸防腐剂可通过破坏酸性成分来减少有害酸性物质的形成。燃烧会产生大量的副产品，包括酸性物质的形成。燃烧会产生大量的副产品，包括酸和水。防腐剂可在它们损害发动机之前中和这些副和水。防腐剂可在它们损害发动机之前中和这些副产品。在冷机、浓可燃混合气、调试不好的

47、发动机产品。在冷机、浓可燃混合气、调试不好的发动机以及短程、寒冷的天气下运转都会增加酸性物质。以及短程、寒冷的天气下运转都会增加酸性物质。Antiscuff additives help to polish moving parts, including cams, pistons , and cylinder walls . This is particularly important during new engine break-in and after an engine overhaul. Since heat is the prime enemy of antiscuff addi

48、tives, operating conditions that produce excessively high engine temperatures reduce the life expectancy of these additives. This type of operation requires more fre-quent oil changes than does normal operation.译文：译文：防擦伤（抛光）添加剂有助于抛光（磨光防擦伤（抛光）添加剂有助于抛光（磨光）运动部件，如：凸轮，活塞和气缸壁。这在新发）运动部件，如：凸轮，活塞和气缸壁。这在新发动机磨

49、合期间或发动机大修后是非常重要的。因为动机磨合期间或发动机大修后是非常重要的。因为热量是抛光添加剂的最大危害，所以发动机高温运热量是抛光添加剂的最大危害，所以发动机高温运行时会减小这些添加剂的预期寿命。高温条件下比行时会减小这些添加剂的预期寿命。高温条件下比正常工作，润滑油更换要更频繁一些。正常工作，润滑油更换要更频繁一些。Detergent- dispersants clean engine parts during operation and keep these contaminants in sus-pension in the oil. As the oil is force thr

50、ough the filter, the majority of these contaminants are trapped by the filter.译文：译文：清洁分散剂可在发动机工作时，清洁发动清洁分散剂可在发动机工作时，清洁发动机部件，并使那些污染物悬浮在机油中。当机油通机部件，并使那些污染物悬浮在机油中。当机油通过滤清器时，大部分污染物就可被滤清器过滤掉。过滤清器时，大部分污染物就可被滤清器过滤掉。Viscosity index improvers tend to stabilize or improve the viscosity of engine oils at vario

51、us tem-peratures. They tend to give the oil more body when the oil is cold. In other words, they improve the body and fluidity of the oil. The ability of the oil to carry a load at high temperature is improved by this additive, and the ability of the oil to flow when cold is also improved.译文：译文：粘度指数

52、提高剂可稳定或提高发动机机油粘度指数提高剂可稳定或提高发动机机油在各种温度条件下的粘度。在机油温度低时，会增在各种温度条件下的粘度。在机油温度低时，会增加机油的浓度。换句话说，它可提高机油的粘度和加机油的浓度。换句话说，它可提高机油的粘度和流动性。这种添加剂可提高机油在高温时携带负载流动性。这种添加剂可提高机油在高温时携带负载的能力以及在低温时的流动性。的能力以及在低温时的流动性。Foam inhibitors reduce the tendency of oil to foam. Heat and agitation mix the oil with air to create foam.

53、Oil foam reduces the lubricating ability of the oil and causes oil starvation and failure of engine parts. Loss of oil pressure due to foaming increases this problem.译文：译文：泡沫抑制剂可减小机油起泡沫。把机油和泡沫抑制剂可减小机油起泡沫。把机油和空气混合在一起热搅拌会产生泡沫。机油泡沫会降空气混合在一起热搅拌会产生泡沫。机油泡沫会降低机油的润滑能力，并造成缺油和发动机部件损坏低机油的润滑能力，并造成缺油和发动机部件损坏。由于起

54、泡所引起的油压降低会使这种情况增多。由于起泡所引起的油压降低会使这种情况增多。I. Answer the following questions:1. What is the purpose of automobile lubrication system?Reducing friction to minimize wear and loss of power.2. How does internal engine leakage affect oil pressure?3. Explain what the function of oil is.The engine oil forms a

55、seal between the pistons, rings, and cylinders. It also helps to cool en-gine parts. Without the cleaning action of the lubricating system, carbon and varnish buildup would be excessive. The engine oil also absorbs the shock and dampens the noise of moving parts.4 Name at least three common additive

56、s used in compounding motor oils. 5. Describe how oil pumps and engine lubrication work .The oil pump is in the crankcase above the sump and draws oil through a tube that extends downward into the sump. The oil is pumped between all the moving parts of the engine . the oil serves two purposes. One purpose is to lubricate the bearing sur-faces. The other purpose is to cool the bearings by