汽車專業(yè)英語教程多媒體教學(xué)課件Unit7section4

1、1 Engine Cooling System The purpose of the cooling system is to keep the engine at its most efficient operting temperature at all engine speeds and all driving con-ditionsSection 4 Engine Cooling and Lubricating Systems 發(fā)動機(jī)冷卻與潤滑系統(tǒng)（一）發(fā)動機(jī)冷卻系統(tǒng) 冷卻系統(tǒng)的作用是控制發(fā)動機(jī)的溫度，使發(fā)動機(jī)在各種轉(zhuǎn)速和各種行駛狀態(tài)下都能有效地工作。 A great deal of

2、heat is produced in the engine by the burning of the air-fuel mixtureSome of this heat escapes from the engine through the exhaust gases to keep the engine from over-heatingBut enough remains in the engine to cause serious trouble，the cooling system takes care of this ad-ditional heatAnother importa

3、nt job of the cooling system is to allow the engine to heat up as quickly as pos-sible，and then to keep the engine at a constant temperature There are two types of cooling sys-tems found on cars：liquid-cooled and air-cooled 混合氣的燃燒在發(fā)動機(jī)中產(chǎn)生大量的熱，其中部分熱量通過廢氣被排出以阻止發(fā)動機(jī)過熱。但是，殘留在發(fā)動機(jī)中的余熱仍足以使發(fā)動機(jī)受到嚴(yán)重?fù)p壞，冷卻系統(tǒng)就是專門用

4、來消除余熱的。冷卻系統(tǒng)還有一個(gè)重要任務(wù)，就是讓發(fā)動機(jī)迅速預(yù)熱，然后就讓發(fā)動機(jī)保持恒定的溫度。 冷卻系統(tǒng)有兩種：液冷和風(fēng)冷。 The cooling system on liquid-cooled cars circulates a fluid through pipes and passageways in the engineAs this liquid passes through the hot en-gine it absorbs heat，cooling the en-gineAfter the fluid leaves the engine，it passes through a

5、heat exchanger，or radiator，which transfers the heat from the fluid to the air blowing through the exchanger Some older cars，and very few mo-dem cars，are air-cooledSince most cars are liquid-cooled，we will focus on that system in this article 液冷系統(tǒng)的流體在發(fā)動機(jī)中的管路和通道中循環(huán)流動。當(dāng)液體流過發(fā)熱的發(fā)動機(jī)時(shí)，就吸收了大量熱量。當(dāng)液體流出發(fā)動機(jī)時(shí)，通過

6、熱交換器或散熱器，將液體變?yōu)闅怏w吹走。 有些老式汽車和少數(shù)現(xiàn)代汽車采用風(fēng)冷系統(tǒng)。因?yàn)榇蟛糠值钠嚥捎靡后w冷卻，所以我們主要討論液冷系統(tǒng)。 The liquid cooling system consists of water pumps，water jackets，engine fan，radiator，coolant reservoir tank，radiator cap，thermostat，hoses and so on，as is shown in Fig. 7-26The cooling system is built into the engineThere are hollow

7、spaces around each engine cylinder and combustion chamberThese hollow spaces are called water jackets，since they are filled with waterWhen the engine is running，the water takes heat from the engine，becoming hot in the processA water pump pumps the hot water from the engine water jackets into the rad

8、iator 液體冷卻系由水泵、水套、發(fā)動機(jī)風(fēng)扇、散熱器（水箱）、副水箱、壓力式水箱蓋、節(jié)溫器、水管等組成，如圖7-26所示。冷卻系統(tǒng)就設(shè)置在發(fā)動機(jī)中。每個(gè)氣缸體和燃燒室周圍都留有空腔，這些空腔裝滿了水，稱之為水套。在發(fā)動機(jī)運(yùn)行過程中水被加熱，并以水循環(huán)方式把熱量從發(fā)動機(jī)中帶走。水泵從發(fā)動機(jī)水套中把熱水抽到散熱器中，The radiator has two sets of pas-sagesOne set carries waterThe other set carries air（pulled through by car motion and the engine fan）As the ho

9、t water passes through，it gives up its heat to the air passing throughThe cooled water then reen-ters the engine，where it can pick up more heatIn operation，water conti-nuously circulates between the engine and radiator，carrying heat from the engine to the radiatorBy this means，excessive engine tempe

10、ratures are prevented散熱器有兩條通道：一條是水道，另一條是氣道（空氣是通過汽車行駛和發(fā)動機(jī)的風(fēng)扇抽入的）。當(dāng)熱水流過水道時(shí)，氣道中流通的空氣使熱水冷卻，冷卻后的水又重新進(jìn)入發(fā)動機(jī)，再把發(fā)動機(jī)中的熱量傳導(dǎo)出去。在這一過程中，水不斷地在發(fā)動機(jī)與散熱器之間循環(huán)，水?dāng)y帶著熱量從發(fā)動機(jī)流到散熱器再散發(fā)出去。通過這個(gè)方法可避免發(fā)動機(jī)溫度過高。98764532110Fig. 7-261Water Jacket；水套2Heater；暖氣水箱3Heater Hose；暖氣水管4Thermostat；節(jié)溫器5Water Pump；水泵6Pressure Cap；壓力式水箱蓋7Coolant

11、Reservoir Tank；副水箱8Radiator Core；散熱器芯9Hoses；水管10Fan Belt；風(fēng)扇皮帶 The water pump is a simple cen-trifugal pumpThe water pump，driven by a belt from the engine crankshaft，circulates the cooling liquid between the radiator and engine water jacketsThe cooling liquid is waterAntifreeze com-pounds are added t

12、o the water during the winterThe water jacket are cast into the cylinder blocks and headsThe engine fan is us-ually mounted on the water pump shaft and is driven by the same belt that drives the pump and the ge-nerator，see Fig. 7-27 水泵就是個(gè)簡單的離心泵。水泵由發(fā)動機(jī)曲軸上的皮帶驅(qū)動，使冷卻液在散熱器與發(fā)動機(jī)水套之間循環(huán)流動。冷卻液是水，冬季在水中須加入防凍劑。水

13、套被鑄入氣缸體和氣缸蓋內(nèi)部。發(fā)動機(jī)風(fēng)扇通常安裝在水泵軸上，由驅(qū)動水泵和發(fā)電機(jī)的同一條皮帶驅(qū)動，參見圖7-27。The purpose of the fan is to provide a powerful draft of air through the radiatorThe radiator is a device for holding a large volume of water in close contact with a large volume of air so that heat will transfer from the water to the airThe rad

14、iator core is divided into two separate and intri-cate compartments；water passes through one，and air passes through the other 風(fēng)扇的作用是向散熱器提供強(qiáng)大的空氣流，與大量空氣密切接觸的散熱器內(nèi)可以容納大量的水，這樣熱量可以通過水散發(fā)到空氣中。散熱器芯為分離和間隔交錯(cuò)的兩部分。冷卻水在其中一部分中流過，空氣在另一部分中通過。Fig. 7-271231Water Pump；水泵2Pulley；皮帶盤3Cooling Fan；冷卻風(fēng)扇 The radiator is the

15、largest part of the cooling system，most of the heat from the engine is transferred from the coolant to the surroun-ding air，as is shown in Fig. 7-28The reservoir tank is connected to the overflow hoseWhen the hot coolant expands in the radiator，the reservoir tank allows coolant to flow inAs the syst

16、em cools，the coolant will be drawn back into the radiator 水箱是冷卻系最大的零件，大部分發(fā)動機(jī)的熱量由冷卻液散發(fā)至周圍空氣中，如圖7-28所示。副水箱連接溢流管，當(dāng)熱冷卻液在水箱內(nèi)膨脹，冷卻液便流入副水箱；當(dāng)冷卻系溫度下降后，冷卻液又再從副水箱流回水箱。876543219Fig. 7-281Reservoir Tank；副水箱2Pressure Cap；壓力式水箱蓋3Upper Tank；上水箱4Upper Hose；上水管5Lower Hose；下水管6Drain；放水塞7Lower Tank；下水箱8Radiator Core；水箱

17、芯子9Overflow Hose；溢流管 The radiator is normally equipped with a pressure cap or radiator cap that tightly seals the radiator，as is shown in Fig. 7-29This allows the coolant to rise above 100 in temperature without boilingThe thermostat is an important compo-nent that controls coolant flow and engine t

18、emperatureIt is operated by a wax capsule or pelletIf you see a thermostat marked 82，it means the thermostat will begin to open at 82 水箱通常配有壓力式水箱蓋（壓力蓋或水箱蓋）以緊緊密封水箱，如圖7-29所示。如此可讓冷卻液溫度升高至100以上而不沸騰。節(jié)溫器是控制冷卻液流動及發(fā)動機(jī)溫度的重要元件，它由石蠟制小容器或石蠟丸來動作，如果你看到節(jié)溫器上標(biāo)有82，它表示節(jié)溫器將在82時(shí)打開。12431Vacuum Valve；真空閥2Pressure Cap；壓力式水

19、箱蓋3Overflow Tube；溢流管4Wax；蠟丸Fig. 7-29 A radiator is a type of heat ex-changerIt is designed to tran-sfer heat from the hot coolant that flows through it to the air blown through it by the fan The thermostats main job is to allow the engine to heat up quickly，and then to keep the engine at a constant

20、tempe-ratureIt does this by regulating the amount of water that goes through the radiator Like the thermostat，the coo-ling fan has to be controlled so that it allows the engine to main-tain a constant temperature 散熱器（水箱）是熱交換器的一種。散熱器將發(fā)熱的冷卻液的熱量傳遞給空氣，然后用風(fēng)扇吹入大氣。 節(jié)溫器的主要任務(wù)是使發(fā)動機(jī)迅速預(yù)熱，然后使發(fā)動機(jī)保持一個(gè)恒定的溫度。這是通過調(diào)節(jié)流

21、過散熱器的水流量來調(diào)節(jié)的。 就像節(jié)溫器一樣，冷卻風(fēng)扇能使發(fā)動機(jī)維持在一個(gè)恒定溫度。 2 Engine Lubricating System The main components of engine lubri-cation system are the oil pan，oil pump，engine oil passages and oil fil-ter，as is shown in Fig. 7-30 and Fig. 7-31 發(fā)動機(jī)潤滑系統(tǒng)主要元件有油底殼、機(jī)油泵、發(fā)動機(jī)油道和機(jī)油濾清器，如圖7-30、7-31所示。654321Fig. 7-301Cylinder Head Oil

22、Gallery；汽缸蓋油道2Hydraulic Valve Lifter；液壓閥挺桿3Main Oil Gallery；主油道4Oil Filter；濾油器5Oil Pump；油泵6Oil Pan；油底殼1Valve of Oil Radiator Passage；通機(jī)油散熱器的閥門2Centrifugal Oil Fine Filter；離心式機(jī)油細(xì)濾器3Oiled Relief Valve of Fine Filter；細(xì)濾器進(jìn)油限壓閥4Oil strainer；機(jī)油集濾器5Magnetism Purge Cock；磁性放油螺塞6Oil Relief Valve；機(jī)油限壓閥7Oil Pum

23、p；機(jī)油泵8Oil Tube；油管9Oil First Filter；機(jī)油粗濾器10Oil bypass-valve；機(jī)油旁通閥Fig. 7-3111Oil Passage of Connecting Rod Small End；連桿小頭油道12Injector to Lubricate Timing Gear；潤滑正時(shí)齒輪噴油嘴13Tabula Oil Passage；橫隔油道14Main Oil Gallery；主油道15Transmission Shaft of Oil Pump；油泵傳動軸16Oil Passage Lead to rockshaft；通搖臂軸油道17Arm Shaft

24、；臂軸Fig. 7-31 The most common types of oil pumps are the gear type and the rotor type，as is shown in Fig. 7-32The gear type uses a drive gear and a driven gearWhen the engine starts，oil is pushed into the small spaces between the gears and the housingThe oil，under pres-sure，will be sent to the oil fi

25、l-terThe rotor type contains two ro-tors in the pump bodyThe rotors rotate in the same direction causing the oil to be drawn into or out of the oil pump when the volume increases or decreases 機(jī)油泵最常見的是齒輪式和轉(zhuǎn)子式，如圖7-32所示。齒輪式機(jī)油泵利用一個(gè)主動齒輪和一個(gè)被動齒輪，只要發(fā)動機(jī)一啟動，機(jī)油便被擠入介于齒輪與外殼間的小空間中，接著被壓送至機(jī)油濾清器。轉(zhuǎn)子式機(jī)油泵在泵體內(nèi)有兩個(gè)轉(zhuǎn)子，轉(zhuǎn)子以相

26、同方向旋轉(zhuǎn)并改變兩者間的容積，當(dāng)容積增加或減少時(shí)，機(jī)油則流入或流出機(jī)油泵。Fig. 7-32123435（a）Gear Type 齒輪式 （b）Rotor Type 轉(zhuǎn)子式1Drive Gear；主動齒輪2Driven Dear；從動齒輪3Housing；外殼4Driven Rotor；從動轉(zhuǎn)子5Drive Rotor；主動轉(zhuǎn)子 The oil pan contains oil and trans-fer heat from the hot oil to the sur-rounding airThe oil pump supplies oil under pressure to the mo

27、ving parts of the engine The engine oil filter is designed to remove minute panicles of metal and dirt from the engine oilWhen the filter is restricted，the oil cant reach the bearings and damage will occurAt this point，the pressure relief valve will open and the unfil-tered oil can flow to lubricate

28、 the en-gine，see Fig. 7-33 油底殼能保存機(jī)油并將機(jī)油的熱量傳遞到周圍的空氣中，機(jī)油泵再將機(jī)油壓送至友動機(jī)的旋轉(zhuǎn)元件。 機(jī)油濾清器的作用是濾除機(jī)油中細(xì)小的金屬微粒和污物。當(dāng)機(jī)油濾清器堵塞，機(jī)油無法到達(dá)軸承時(shí)，發(fā)動機(jī)會損壞，此時(shí)減壓閥將會開啟，未經(jīng)過濾的機(jī)油就能流出以潤滑發(fā)動機(jī)，參見圖7-33。1Pressure Relief Valve；泄壓閥2Pressure Relief Valve Open；打開單向閥2121Fig. 7-33 The lubricant is used to protect the automotive componentIn some cas

29、es this protection is in the form of a fluid film that keeps opposing surfaces separatedIn other cases，the lubri-cant provides wear protection by for-ming a chemical film on a surface，to generate boundary lubrication prote-ctionAutomotive lubricants protect against corrosion by virtue of alka-line a

30、gents to neutralize acids that form in hot spots Under highly loaded and high tem-perature conditions，fluid film lub-rication may not be sufficient to provide complete wear protection， 潤滑劑是用來保護(hù)汽車零件的。有時(shí)候通過在零件表面形成油膜使相接觸表面分開來保護(hù)零件，有時(shí)候通過提供化學(xué)膜而增加零件表面抗磨性來保護(hù)零件。汽車潤滑劑通過利用其堿性中和酸起到對高溫零件表面的防腐作用。 在高負(fù)荷高溫條件下，油膜潤滑不能

31、完全有效地提供摩擦保護(hù)，the lubricant must contain additives so that interact with rubbing surfaces to form antiwear films The engine lubrication system must perform many direct function，but how successful the lubrication system is in performing all these functions depends on a number of factors and conditionsF

32、or example，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 surfaces subject to sliding frictionIn addition，潤滑油必須含有添加劑，從而在摩擦表面起作用，形成耐磨層。 潤滑系統(tǒng)必須執(zhí)行很多功能，但是

33、否能成功地實(shí)現(xiàn)所有這些功能與很多因素和條件有關(guān)。例如，必須要有足夠的質(zhì)量好的潤滑劑輸送到所有的發(fā)動機(jī)運(yùn)動零件上，為運(yùn)動零件提供液力潤滑，同時(shí)也為受滑動摩擦影響的表面提供液力潤滑。此外， The oil and filter must be chan-ged at regular intervals The engine must operate at its most efficient temperature Engine oil temperatures must not be excessively hot or cold 在規(guī)定的時(shí)間間隔內(nèi)更換機(jī)油和過濾器。 發(fā)動機(jī)必須在有效的溫度下工

34、作。 發(fā)動機(jī)機(jī)油溫度不許過熱或過冷。 Reading Material1 Thermostat（節(jié)溫器） The thermostat is the engine temperature control unitSee Fig. 7-34，The thermostat blocks the coolant flow to the radiator until the engine reaches normal operating temperatures1652437Cold CoolentHot CoolentHot Coolent to Radiator（a）Engine Cold The

35、rmostat Closed （b）Engine Hot Thermostat Open Fig. 7-34 Thermostat Situation1Bypass Passage；2Thermostat Housing；3Valve（Closed）；4Metal Piston；5Return Spring；6Wax Pellet；7Valve（Open） Until engine warm-up occurs，the thermostat remains clo-sedCoolant flows back through the engine block via the water pump

36、 bypass passageThereforethe coolant flows past the cylinders again without the advantage of radiator coolingThus the engine warms quickly and evenly When the temperature rises to a preset point determined by the thermostats calibration，the thermostat begins to openThe coo-lant then flows through the

37、 thermostatThe flow continues through the upper radiator hoseThe coolant then enters the inlet tank of the radiatorFrom there，it passes through file radiator cooling tubes If the thermostat stick is closed，the engine will overheat be-cause of inadequate coolant flowIf the thermostat stick opens (or

38、is removed)，the engine will not warm up as quickly as it shouldLonger warm-up time can result in poor fuel economy，high exhaust Emissions，and deposit build-up in the engine.2 Oil Temperature Sending Unit（油溫傳感器） An oil temperature sending unit is used on some vehiclesThis sending unit is a thermistor

39、（熱敏電阻）Changes in engine oil（機(jī)油）temperature affect the resistance of the thermistorAs with an oil pressure display，the sending unit resistance determines the amount of current flow through the display circuitIn this case the instrument panel（儀表盤）displays oil temperature instead of oil pressure（油壓） 1）

40、Motor Oil（機(jī)油；馬達(dá)油） Motor oil is the lifeblood（命根子）of an engineWithout a good-quality oil，engine life would be very shortMotor oil performs five tasksIt must： LubricateIt prevents excessive friction（過份摩擦）between moving parts CoolThe circulating oil（循環(huán)油）carries heat away from high-temperature component

41、s such as pistons and bearings SealAn oil film helps seal（密封）between the piston rings and cylinder Walls CleanOil additives help to prevent deposit buildup on engine parts and surfaces ProtectOil additives protect against rust（生銹），corrosion（腐蝕）and abnormal wear（不規(guī)則磨損） Motor oil consists of base oils

42、 plus an additive packageBase oils may be made from either petroleum（mineral oil）or synthetic（ma-nufactured） materialsAn additive package improves the natural properties of the oil to make a better lubricant 2）Oil Viscosity（油黏度） Water and gasoline are“thin”（稀的；低黏度的）liquids that flow easilyThey have

43、low viscosityViscosity is a measure of a liquids resistance to flowMotor oils and gear oils are“thicker（稠化劑；增稠劑）”liquids with more resistance to flowThey have higher visco-sityThe viscosity of oil is affected by（受影響）temperature A thin and low viscosity oil will flow easily at low temperaturesHowever，it will be too thin for good lubrication when the engine warms upA thicker and higher viscosity oil flows more slowlyIt will provide good lubrication at high temperatures but may be