汽車專業(yè)英語_3_AUTOMOTIVE_LUBRICATION_SYSTEM課件

1、Chapter 3 AUTOMOTIVE LUBRICATION SYSTEMu 背景知識背景知識 發(fā)動機工作時，很多傳動零件都是在發(fā)動機工作時，很多傳動零件都是在很小的間隙很小的間隙下作高速相下作高速相對運動的，如對運動的，如曲軸主軸頸曲軸主軸頸與與主軸承主軸承，曲柄銷曲柄銷與與連桿軸承連桿軸承，凸輪軸凸輪軸頸與凸輪軸承頸與凸輪軸承，活塞、活塞環(huán)與氣缸壁面活塞、活塞環(huán)與氣缸壁面，配氣機構(gòu)各運動副配氣機構(gòu)各運動副及及傳動齒輪副傳動齒輪副等。盡管這些零件的工作表面都經(jīng)過精細的加工，但等。盡管這些零件的工作表面都經(jīng)過精細的加工，但放大來看這些表面卻是凹凸不平的。放大來看這些表面卻是凹凸不平的。若不

2、對這些表面進行潤滑，它們之間將發(fā)生強烈的摩擦。金若不對這些表面進行潤滑，它們之間將發(fā)生強烈的摩擦。金屬表面之間的干摩擦不僅增加發(fā)動機的功率消耗，加速零件工作屬表面之間的干摩擦不僅增加發(fā)動機的功率消耗，加速零件工作表面的磨損，而且還可能由于摩擦產(chǎn)生的熱將零件工作表面燒損表面的磨損，而且還可能由于摩擦產(chǎn)生的熱將零件工作表面燒損，致使發(fā)動機無法運轉(zhuǎn)。，致使發(fā)動機無法運轉(zhuǎn)。 Chapter 3 AUTOMOTIVE LUBRICATION SYSTEM潤滑方式潤滑方式 由于發(fā)動機傳動件的工作條件不盡相同，因此，對負荷及相對由于發(fā)動機傳動件的工作條件不盡相同，因此，對負荷及相對運動速度不同的傳動件采用不

3、同的潤滑方式。運動速度不同的傳動件采用不同的潤滑方式。 1)壓力潤滑壓力潤滑壓力潤滑是以一定的壓力把機油供入摩擦表面的潤滑方式。這種方壓力潤滑是以一定的壓力把機油供入摩擦表面的潤滑方式。這種方式主要用于主軸承、連桿軸承及凸輪軸承等負荷較大的摩擦表面式主要用于主軸承、連桿軸承及凸輪軸承等負荷較大的摩擦表面的潤滑。的潤滑。 2)飛濺潤滑飛濺潤滑利用發(fā)動機工作時運動件濺潑起來的油滴或油霧潤滑摩擦表面的潤利用發(fā)動機工作時運動件濺潑起來的油滴或油霧潤滑摩擦表面的潤滑方式，稱飛濺潤滑。該力式主要用來潤滑負荷較輕的氣缸壁面滑方式，稱飛濺潤滑。該力式主要用來潤滑負荷較輕的氣缸壁面和配氣機構(gòu)的凸輪、挺柱、氣門桿

4、以及搖臂等零件的工作表面。和配氣機構(gòu)的凸輪、挺柱、氣門桿以及搖臂等零件的工作表面。 3)潤滑脂潤滑潤滑脂潤滑通過潤滑脂嘴定期加注潤滑脂來潤滑零什的工作表面，如水泵及發(fā)通過潤滑脂嘴定期加注潤滑脂來潤滑零什的工作表面，如水泵及發(fā)電機軸承等。電機軸承等。 Chapter 3 AUTOMOTIVE LUBRICATION SYSTEM New Wordsresidual rzdu:ladj.剩余的，殘留的剩余的，殘留的varnish v:nin.清漆，積碳清漆，積碳buildupn.組合組合,集結(jié)集結(jié),累積累積,形成形成adhesion dhi:nn.粘著，附著，粘連粘著，附著，粘連cleanser

5、klenzn.清潔劑清潔劑sludgesldn.油泥油泥grime gramn.污垢，塵垢，煙灰污垢，塵垢，煙灰clogklv.填塞，塞滿填塞，塞滿gummvt.粘合粘合troughtr:f,trfn.槽，水槽，飼料槽，水盆，任何槽形物槽，水槽，飼料槽，水盆，任何槽形物bafflebfln.阻板，隔板阻板，隔板sumpsmpn.油底殼油底殼crankcasekrkkeisn.曲軸箱曲軸箱 New Wordsporosityp:rsitin.多孔性多孔性,有孔性有孔性peripheryprfri:n.外圍外圍syntheticsinetikadj.合成的，人造的，綜合的合成的，人造的，綜合的Ad

6、ditiveditivn.添加劑；添加劑；adj.添加的，附加的，加法的添加的，附加的，加法的antiscuffn.磨損磨損overhaulvh:l,vh:lvt.徹底檢查，大修徹底檢查，大修neutralizenu:trlaz,nju:-vt.使無效，抵消，使中和使無效，抵消，使中和agitationdtenn.激動，興奮，煽動，攪動激動，興奮，煽動，攪動 PHRASES AND EXPRESSIONS start-up起（啟）動起（啟）動 engineblock發(fā)動機氣缸體發(fā)動機氣缸體 dry-sump干油底殼干油底殼 wet-sump濕油底殼濕油底殼Chapter 3 AUTOMOTIV

7、E LUBRICATION SYSTEM PHRASES AND EXPRESSIONSpickuptube機油吸油管機油吸油管filterscreen濾網(wǎng)濾網(wǎng)full-flowfilteringsystem全流式濾清器全流式濾清器pressure-reliefvalve安全閥，泄壓閥安全閥，泄壓閥bypassvalve旁通閥旁通閥geartypeoilpump齒輪式機油泵，齒輪泵齒輪式機油泵，齒輪泵jockeypulley張緊輪，導向輪張緊輪，導向輪corrosioninhibitor阻蝕劑，腐蝕抑制劑阻蝕劑，腐蝕抑制劑detergent-dispersant清潔分散劑清潔分散劑viscos

8、ityindex粘度指數(shù)粘度指數(shù)foaminhibitor泡沫抑制劑泡沫抑制劑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譯文：譯文：減小摩擦，降低

9、磨損和動力損失是潤滑系減小摩擦，降低磨損和動力損失是潤滑系統(tǒng)必須完成的主要工作。發(fā)動機部件上的殘油也統(tǒng)必須完成的主要工作。發(fā)動機部件上的殘油也可為發(fā)動機起動提供潤滑?？蔀榘l(fā)動機起動提供潤滑。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.譯文：譯文：發(fā)動機機油在活塞、活塞環(huán)和氣缸間形成密封。發(fā)動機機油在活塞、活塞環(huán)和氣缸間形成密封。它也有助于冷卻發(fā)動機部件。如果沒有潤滑系統(tǒng)的清潔它也有助于冷卻發(fā)動機部件。如果沒有潤滑系統(tǒng)的清潔作用，積碳會過量集結(jié)。機油還可減震和消弱（抑制）作用，積碳會過量集結(jié)。機油還可減震和消弱（抑制）運動部件噪聲。運動部件噪聲。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.譯文：譯文：潤滑系統(tǒng)在執(zhí)行這些功能時的成功程度由許多因潤滑系統(tǒng)在執(zhí)行這些功能時的成功程度由許多因素和條件所決定。充足的優(yōu)質(zhì)潤滑油在壓力作用下輸送素和條件所決定。充足的優(yōu)質(zhì)潤滑油在壓力作用下輸送到各運動發(fā)動機部件，以此來為所有轉(zhuǎn)動部件提供流體到各運動發(fā)動機部件，以此來為所有轉(zhuǎn)動部件提供流體動力潤滑，機油附著在滑動摩擦的部件表面。動力潤滑，機油附著在滑動摩擦的部件表面。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譯文：譯文：油底殼用螺栓固定在發(fā)動機氣缸體下方，油底殼用螺栓固定在發(fā)動機氣缸體下方，封閉發(fā)動機的底部。它的形狀像一個溝槽，由薄封閉發(fā)動機的底部。它的形狀像一個

14、溝槽，由薄鋼板制成，可儲存大約鋼板制成，可儲存大約5 5夸脫的機油。當機油從發(fā)夸脫的機油。當機油從發(fā)動機流出時，它將向下排入到油底殼中動機流出時，它將向下排入到油底殼中。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.譯文：譯文：油泵從油底殼的最低處抽油。許多油底殼帶有薄油泵從油底殼的最低處抽油。許多油底殼帶有薄金屬隔板。它們可在汽車急轉(zhuǎn)彎或突然剎車時將機油保金屬隔板。它們可在汽車急轉(zhuǎn)彎或突然剎車時將機油保持在油底殼中。放

16、油塞位于油底殼底部，可通過它將機持在油底殼中。放油塞位于油底殼底部，可通過它將機油從發(fā)動機排出。油底殼襯墊裝在油底殼和氣缸體底端油從發(fā)動機排出。油底殼襯墊裝在油底殼和氣缸體底端之間。之間。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. 譯文：譯文：在大多數(shù)發(fā)動機上，機油在發(fā)動機內(nèi)循環(huán)后要回在大多數(shù)發(fā)動機上，機油在發(fā)動機內(nèi)循環(huán)后要回到油底殼中。然后一直在那里存放，直到被油泵抽回到到油底殼中。然后一直在那里存放，直到被油泵抽回到發(fā)動機。在這個運行過程中，油底殼只有發(fā)動機。在這個運行過程中，油底殼只有2 23 3夸脫機夸脫機油，其余的潤滑系統(tǒng)通道內(nèi)流動。油，其余的潤滑系統(tǒng)通道內(nèi)流動。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.譯文：譯文：發(fā)動機熄火（停轉(zhuǎn)）時，油底殼有發(fā)動機熄火（停轉(zhuǎn)）時，油底殼有4 4夸脫機油夸脫機油，另外一夸脫的機油留在機油濾清器里。因為機油一直，另外一夸脫的機油留在機油濾清器里。因為機油一直保持在油底殼中，所以這種類型的潤滑系統(tǒng)也稱為濕式保持在油底殼中，所

19、以這種類型的潤滑系統(tǒng)也稱為濕式油底殼潤滑系統(tǒng)。油底殼潤滑系統(tǒng)。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.譯文：譯文：干式油底殼潤滑系統(tǒng)在許多賽車發(fā)動機中采用。干式油底殼潤滑系統(tǒng)在許多賽車發(fā)動機中采用。這個系統(tǒng)有單獨的存儲油箱。只要機油從發(fā)動機排出，就這個系統(tǒng)有單獨的存儲油箱。只要機油從發(fā)動機排出，就立即被第二個油泵從油底殼中抽出。因此，干式油底殼系立即被第二個油泵從油底殼中抽出。因此，干式油底殼系統(tǒng)要比濕式油底殼系統(tǒng)在發(fā)動機循環(huán)更多的機油。統(tǒng)要比濕式油底殼系統(tǒng)在發(fā)動機循環(huán)更多的機油。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. 譯文：譯文：在多數(shù)汽車上，油泵位于油底殼上方的曲在多數(shù)汽車上，油泵位于油底殼上方的曲軸箱中。它通過延伸到油底殼中的油管把機油抽軸箱中。它通過延伸到油底殼中

22、的油管把機油抽出。這個管稱為油泵吸油管，在它的底端帶有一出。這個管稱為油泵吸油管，在它的底端帶有一個濾網(wǎng)。濾網(wǎng)可防止將大塊的油泥和污垢抽到油個濾網(wǎng)。濾網(wǎng)可防止將大塊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.譯文：譯文：吸油管用鉸鏈接合在油泵末端，以便它能吸油管用鉸鏈接合在油泵末端，以便它能夠隨油底殼內(nèi)的油面變化而上下浮動。因此，油夠隨油底殼內(nèi)的油面變化而上下浮動。因此，油泵是從油底殼上面抽油，而不是從其底部油泥和泵是從油底殼上面抽油，而不是從其底部油泥和污垢沉積的地方抽油。油泵有兩種類型，污垢沉積的地方抽油。油泵有兩種類型，齒輪式齒輪式和轉(zhuǎn)子式和轉(zhuǎn)子式?，F(xiàn)代汽車一般可采用其中的一種。

24、現(xiàn)代汽車一般可采用其中的一種。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. 譯文：譯文：現(xiàn)代汽車采

25、用全流式過濾系統(tǒng)。在這個系現(xiàn)代汽車采用全流式過濾系統(tǒng)。在這個系統(tǒng)中，油泵輸出機油要先流過機油濾清器，然后統(tǒng)中，油泵輸出機油要先流過機油濾清器，然后才穿過發(fā)動機。換句話說，機油在到達發(fā)動機各才穿過發(fā)動機。換句話說，機油在到達發(fā)動機各處之前被過濾和凈化。處之前被過濾和凈化。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.譯文：譯文：當發(fā)動機轉(zhuǎn)速在當發(fā)動機轉(zhuǎn)速在3000rpm3000rpm時，時，5 5夸脫機油夸脫機油每分鐘至少穿過濾清器一次。因而機油濾清器可每分鐘至少穿過濾清器一次。因而機油濾清器可確保只有潔凈的機油才能進入發(fā)動機。確保只有潔凈的機油才能進入發(fā)動機。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.譯文：譯文：現(xiàn)代發(fā)動機使用可更換的機油濾清器?，F(xiàn)代發(fā)動機使用可更換的機油濾清器。當它布滿污垢時，這種螺紋連

28、接濾清器就可被換當它布滿污垢時，這種螺紋連接濾清器就可被換成新的。在濾清器的鐵外殼內(nèi)有一層特殊的紙作成新的。在濾清器的鐵外殼內(nèi)有一層特殊的紙作為濾芯。這種紙在被折疊和緊密壓縮后，就具有為濾芯。這種紙在被折疊和緊密壓縮后，就具有了多孔性。紙上的這些小孔能夠濾除機油中的油了多孔性。紙上的這些小孔能夠濾除機油中的油泥和污垢。這種紙經(jīng)過（酚醛樹脂）處理后，在泥和污垢。這種紙經(jīng)過（酚醛樹脂）處理后，在油中具有抗酸性和抗水濕性。油中具有抗酸性和抗水濕性。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. 譯文：譯文：通常，機油是從外面進入機油濾清器。

30、通常，機油是從外面進入機油濾清器。繞底座外圍進入濾清器。機油流過紙濾芯到達容繞底座外圍進入濾清器。機油流過紙濾芯到達容器中心，然后流出到發(fā)動機。大部分濾清器還帶器中心，然后流出到發(fā)動機。大部分濾清器還帶有一個卸壓閥，或稱為旁通閥。它可使機油直接有一個卸壓閥，或稱為旁通閥。它可使機油直接流到發(fā)動機而不需要穿過濾清器。流到發(fā)動機而不需要穿過濾清器。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.譯文：譯文：這在濾清器被嚴重堵塞，機油不能通過這在濾清器被嚴重堵塞，機油不能通過濾芯時是十分必要的。因而，被堵塞的濾清器會濾芯時是十分必要的。因而，被堵塞的濾清器會造成污油在發(fā)動機內(nèi)循環(huán)。為了避免出現(xiàn)這種情造成污油在發(fā)動機內(nèi)循環(huán)。為了避免出現(xiàn)這種情況，機油和機油濾清器應(yīng)該定期更換。況，機油和機油濾清器應(yīng)該定期更換。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譯文：譯文：如果允許運動部件之間金屬接觸，內(nèi)燃機如果允許運動部件之間金屬接觸，內(nèi)燃機運行不了幾分鐘。大量摩擦產(chǎn)生的熱量會把金屬運

33、行不了幾分鐘。大量摩擦產(chǎn)生的熱量會把金屬熔化，導致發(fā)動機的損壞。熔化，導致發(fā)動機的損壞。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. 譯文：譯文：為防止這樣，所有運動部件浮在一層薄為防止這樣，所有運動部件浮在一層薄油膜上，這層油在發(fā)動機各個運動部件之間傳送油膜上，這層油在發(fā)動機各個運動部件之間傳送。運動部件之間的機油有兩個作用，一是潤滑軸。運動部件之間的機油有兩個作用，一是潤滑軸承面承面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.譯文：譯文：另一個是通過吸收摩擦產(chǎn)生的熱量來冷另一個是通過吸收摩擦產(chǎn)生的熱量來冷卻軸承。（到達運動部件的）機油流動是由發(fā)動卻軸承。（到達運動部件的）機油流動是由發(fā)動機的內(nèi)部潤滑系統(tǒng)來實現(xiàn)的。圖機的內(nèi)部潤滑系統(tǒng)來實現(xiàn)的。圖3 32 2是發(fā)動機的是發(fā)動機的潤滑油路簡圖。潤滑油路簡圖。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.譯文：譯文：齒輪式油泵主要由兩個嚙合齒輪構(gòu)成，齒輪式油泵主要由兩個嚙合齒輪構(gòu)成，不需要保養(yǎng)或調(diào)整。它放在油底殼中，由軸和凸不需要保養(yǎng)或調(diào)整。它放在油底殼中，由軸和凸輪軸的斜齒輪驅(qū)動。輪軸的斜齒輪驅(qū)動。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.譯文：譯文：油底殼機油通過氣缸體中的油道和鉆孔油底殼機油通過氣缸體中的油道和鉆孔全壓傳送到所有（曲軸）主軸承和凸輪軸軸承。全壓傳送到所有（曲軸）主軸承和凸輪軸軸承。（連桿）大端軸承潤滑油由主軸承通過曲軸中的（連桿）大端軸承潤滑油由主軸承通過曲軸中的油道提供。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.譯文：譯文：正時鏈條的潤滑由兩路供給，一是從前正時鏈條的潤滑由兩路供給，一是從前凸輪軸軸承到其鏈輪外圍。另一路是先通過正時凸輪軸軸承到其鏈輪外圍。另一路是先通過正時鏈條導輪的空心軸，然后再通過導向輪輪周上的鏈條導輪的空心軸，然后再通過導向輪輪周上的孔?？住he 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. 譯文：譯文：進氣和排氣搖臂軸是空心的，進氣軸由進氣和排氣搖臂軸是空心的，進氣軸由主軸承潤滑油管后端通過一個外部管道供油，而主軸承潤滑油管后端通過一個外部管道供油，而排氣軸和進氣軸從動件潤滑油通過中心凸輪軸軸排氣軸和進氣軸從動件潤滑油通過中心凸輪軸軸承鉆孔提供。承鉆孔提供。 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.譯文：譯文：每個搖臂和挺桿從搖臂軸上所鉆的小孔每個搖臂和挺桿從搖臂軸上所鉆的小孔得到潤滑油，然后機油進入它們本身帶有的孔道得到潤滑油，然后機油進入它們本身帶有的孔道，從這些孔道出來后，再去潤滑與之相連的氣門，從這些孔道出來后，再去潤滑與之相連的氣門、推桿和凸輪軸。分電器傳動軸由排氣搖臂軸通、推桿和凸輪軸。分電器傳動軸由排氣搖臂軸通過一個空心螺栓供油。過一個空心螺栓供油。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.譯文：譯文：來自進氣門配氣機構(gòu)的殘油通過氣缸體來自進氣門配氣機構(gòu)的殘油通過氣缸體回流，而回流，而排氣門配氣機構(gòu)殘油則直接落到油底殼排氣門配氣機構(gòu)殘油則直接落到油底殼中中。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譯文：譯文：汽車發(fā)動機潤滑油有兩種類型：從石油汽車發(fā)動機潤滑油有兩種類型：從石油中提煉出的潤滑油和合成潤滑油。從石油中提煉中提煉出的潤滑油和合成潤滑油。從石油中提煉出的潤滑油含有多種添加劑，因此，實際上也是出的潤滑油含有多種添加劑，因此，實際上也是部分合成的。其主要的添加劑包括以下幾點：部分合成的。其主要的添加劑包括以下幾點：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.譯文：譯文：防腐劑可通過破壞酸性成分來減少有害酸防腐劑可通過破壞酸性成分來減少有害酸性物質(zhì)的形成。燃燒會產(chǎn)生大量的副產(chǎn)品，包括酸性物質(zhì)的形成。燃燒會產(chǎn)生大量的副產(chǎn)品，包括酸和水。防腐劑可在它們損害發(fā)動機之前中和這些副和水。防腐劑可在它們損害發(fā)動機之前中和這些副產(chǎn)品。在冷機、濃可燃混合氣、調(diào)試不好的

47、發(fā)動機產(chǎn)品。在冷機、濃可燃混合氣、調(diào)試不好的發(fā)動機以及短程、寒冷的天氣下運轉(zhuǎn)都會增加酸性物質(zhì)。以及短程、寒冷的天氣下運轉(zhuǎn)都會增加酸性物質(zhì)。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.譯文：譯文：防擦傷（拋光）添加劑有助于拋光（磨光防擦傷（拋光）添加劑有助于拋光（磨光）運動部件，如：凸輪，活塞和氣缸壁。這在新發(fā)）運動部件，如：凸輪，活塞和氣缸壁。這在新發(fā)動機磨

49、合期間或發(fā)動機大修后是非常重要的。因為動機磨合期間或發(fā)動機大修后是非常重要的。因為熱量是拋光添加劑的最大危害，所以發(fā)動機高溫運熱量是拋光添加劑的最大危害，所以發(fā)動機高溫運行時會減小這些添加劑的預期壽命。高溫條件下比行時會減小這些添加劑的預期壽命。高溫條件下比正常工作，潤滑油更換要更頻繁一些。正常工作，潤滑油更換要更頻繁一些。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.譯文：譯文：清潔分散劑可在發(fā)動機工作時，清潔發(fā)動清潔分散劑可在發(fā)動機工作時，清潔發(fā)動機部件，并使那些污染物懸浮在機油中。當機油通機部件，并使那些污染物懸浮在機油中。當機油通過濾清器時，大部分污染物就可被濾清器過濾掉。過濾清器時，大部分污染物就可被濾清器過濾掉。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.譯文：譯文：粘度指數(shù)

52、提高劑可穩(wěn)定或提高發(fā)動機機油粘度指數(shù)提高劑可穩(wěn)定或提高發(fā)動機機油在各種溫度條件下的粘度。在機油溫度低時，會增在各種溫度條件下的粘度。在機油溫度低時，會增加機油的濃度。換句話說，它可提高機油的粘度和加機油的濃度。換句話說，它可提高機油的粘度和流動性。這種添加劑可提高機油在高溫時攜帶負載流動性。這種添加劑可提高機油在高溫時攜帶負載的能力以及在低溫時的流動性。的能力以及在低溫時的流動性。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.譯文：譯文：泡沫抑制劑可減小機油起泡沫。把機油和泡沫抑制劑可減小機油起泡沫。把機油和空氣混合在一起熱攪拌會產(chǎn)生泡沫。機油泡沫會降空氣混合在一起熱攪拌會產(chǎn)生泡沫。機油泡沫會降低機油的潤滑能力，并造成缺油和發(fā)動機部件損壞低機油的潤滑能力，并造成缺油和發(fā)動機部件損壞。由于起

54、泡所引起的油壓降低會使這種情況增多。由于起泡所引起的油壓降低會使這種情況增多。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