汽车构造（发动机）中英文ppt课件.ppt

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1、STRUCTURE OF AUTOMOBILE ENGINE汽车发动机构造汽车运用教研组 黄银娣 开发Chapter 1 :The Internal Combustion Engine 1-1 General Definition: The Internal Combustion engine VS The External Combustion Engine-The combustion(or burning) fuel takes place inside the engine. Fuel: 1. Most automobile engine produce power by burnin

2、g a mixture of air and gasoline ; 2. some kinds of engine by diesel fuel; 3. some by alternative fuels such as CNG（天然气）,LNG（液化石油气）,Methanol(甲醇）,ethanol(乙醇） and etc.汽车运用教研组 黄银娣 开发 2003年8月Main objection: To study the internal combustion engine汽车运用教研组 黄银娣 开发 2003年8月1-2 Gasoline as a fuel know about fol

3、lowing points:NO.1 How the burning of gasoline produces mechanical power ? (1) Gasoline in liquid form is noncombustible(non-burning) (2) however,gasoline Vapor does burn ,combined with air(oxygen in air),gasoline vapor burns inside the engine to produce power. 汽车运用教研组 黄银娣 开发NO.2 How does the liquid

4、 gasoline in the gas tank become gasoline vapor?Evaporation: Gasoline becomes a vapor by evaporation ,which is the process of turning a liquid into a vapor.Gasoline begins to evaporate at a much lower temperature than water : T evaporation of gasoline T evaporation of water it means: Gasoline is mor

5、e easy to vaporize than water.汽车运用教研组 黄银娣 开发Evaporate Evaporation takes place above the surface of a liquid when it is exposed to the air. -thus,gasoline vapor will fill the space above the surface of gasoline. lets have an experiment: see Fig.1-1Remember:there is always vapor above the surface of g

6、asoline. While the liquid may not burn,the vapor will.汽车运用教研组 黄银娣 开发Atomized particlesAtomizer1-1: the vapor made by a spray evaporates quickly.汽车运用教研组 黄银娣 开发Spraying the gasoline into the airThe best way to evaporate gasoline is to expose to the air as much of its surface as possible-to make liquid

7、 gasoline into the tiny droplets.e.g Fig.12 The vapor made by a spray evaporates quickly.汽车运用教研组 黄银娣 开发fuseFuel-air mixturestopper1-2: In this experiment, gasoline vapor burning in a can has enough power to have the stopper out.汽车运用教研组 黄银娣 开发 2003年8月No.3 What happens when gasoline evaporates?The eva

8、porating gasoline mixed with air.The evaporating gasoline expands to fill more space than it did as a liquid.If a flame is touched to this mixture, the gasoline vapor and air burn rapidly producing intense heat. When very hot, the mixture quickly expands even more.汽车运用教研组 黄银娣 开发No.4 What happens to

9、the mixture when it is burned inside a closed container?Fig.1-3Suppose:at the open end of a tin can -put a cork(塞子）； through the closed end -ran a fuse (引线，导火线） closed space filled with fuel-air mixture inside 汽车运用教研组 黄银娣 开发 2003年8月Spark plugExhaust valveIntake valveCombustion chamberpistoncylinder1

10、-3: In this engine. A tight-fitting piston moves up and down in the cylinder. The intake valve takes in vapor. The exhaust valve releases the burned mixture.汽车运用教研组 黄银娣 开发 2003年8月Make an experiment:First: sprayed in a mixture of vaporized gasoline and air with atomizer.Second: lit the fuse Then :the

11、 fuse will ignite the gasoline vapor.The last : the burning vapor would expand with such force that it would blow the stopper off -thats “explosion”conclusion:Internal combustion engine burns gasoline vapor and air to produce power.汽车运用教研组 黄银娣 开发1-3 A One-cylinder Internal Combustion engineThe tin c

12、an - Like the cylinder of engine The stopper in the tin can -Like a piston The fuse in the tin can -Like a spark plug Space between the top of the piston and the top of the cylinder.-The combustion chamber汽车运用教研组 黄银娣 开发Intake valve -the mixture is let in and ignitedExhaust valve-exhaust gas was rele

13、ased from the cylinder through the exhaust valveCrankshaft(曲轴）-looks like a straight bar with an offset(n.偏置）section in the center of it (crankshaft) function: to change pistons up and down motion to the rotation of the crankshaft A connecting rod-joins the piston and the crankshaft Piston Connectin

14、g rod crankshaft1-4: the crankshaft is straight, with an offset section in the middle of it. It is joined to the piston moves the crankshaft. This converts the vertical motion of the piston into the rotary motion of the crankshaft. 汽车运用教研组 黄银娣 开发1-5 Bore and stroke bore(缸径缸径)=D: the distance from on

15、e side of the cylinder to the other side =inner diameter of the cylinder Stroke(行程)：the distance the piston travels from its highest position in the cylinder to its lowest. Offset(偏置又叫曲轴半径)：the offset of the crankshaft is equel to half the distance of the stroke. S=2r You can increase the stroke by

16、increasing the length of the crankshafts offset. TDC(上止点)：the piston actually stops dead at the top is called Top dead center(TDC). BDC(下止点)：the bottom of the piston travel is called bottom dead center (BDC) 1-6 piston strokesIntake stroke ( 进气行程)Compression stroke ( 压缩行程)Power stroke ( 做功行程)Exhaust

17、 stroke ( 排气行程)汽车运用教研组 黄银娣 开发第二节 四冲程发动机工作原理四冲程柴油机四冲程柴油机 工作过程工作过程汽车运用教研组 黄银娣 开发 2003年8月汽车运用教研组 黄银娣 开发 2003年8月1.intake strokes Piston starts downward form TDC to BDC The intake valve opens to take in the air and fuel mixture. 2.Compression stroke The piston starts back up the cylinder again from BDC t

18、o TDC. Both the intake and exhaust valves are closed. The vaporized mixture is contained by the cylinder, it becomes compressed (squeezed) into a very small space. One full revolution : With the intake and compression strokes, the piston has gone from TDC to BDC and back up to TDC again ,the cranksh

19、aft has completed one full revolution . Spark Near the TDC of the compression stroke, the spark plug makes a spark that ignites the mixture which burns rapidly. As mixture burns, it expands, placing great pressure on the piston. 汽车运用教研组 黄银娣 开发 2003年8月3.power stroke Piston downward again on the third

20、 stroke of the engine by the pressure shoves. See fig.1-8 The mixture expands and crankshaft gets power. Intake and exhaust valve all are closed 4. exhaust stroke The piston starts up again, the exhaust valve opens from BDC to TDC. The exhaust valves opens, piston action moves up the cylinder, pushe

21、s the burned gases from the chamber. 汽车运用教研组 黄银娣 开发 2003年8月汽车运用教研组 黄银娣 开发 2003年8月汽车运用教研组 黄银娣 开发汽车运用教研组 黄银娣 开发汽车运用教研组 黄银娣 开发Conclusion: With the combustion chamber empty, the piston can begin another cycle of strokes in the same order. The job of burning the gasoline and air mixture and producing mec

22、hanical power takes four complete strokes of the engine. Two complete revolutions of the crankshaft produce one power stroke. This one power stroke turns the crankshaft, which transfers the mechanical power from the engine. 汽车运用教研组 黄银娣 开发1-7 engine displacement Displacement(容积容积) Cubic-inch displace

23、ment:(汽缸工作容积汽缸工作容积)the volume that the piston displaces inside the cylinder when it travels from BDC to TDC is called the cubic-inch displacement, or CID Displacement of the engine(发动机汽缸工作容积，发动机排发动机汽缸工作容积，发动机排量)=I*Cubic-inch displacement =I */4*b2*S “I” means the numbers of the cylinder 汽车运用教研组 黄银娣

24、开发 2003年8月汽车运用教研组 黄银娣 开发Compression ratioCompression ratio is a comparison between the volume in the cylinder when the piston stands at BDC against the volume at TDC. =Va/Vc car(gasoline): 8:1-11:1; some racing car :13:1-14:1vcvavcvavcva汽车运用教研组 黄银娣 开发汽车运用教研组 黄银娣 开发Review question 1. Why must gasolin

25、e be vaporized in an engine?2.Where is the air-fuel mixture ignited?3.What does the abbreviation TDC stand for?4.what is the final strokes in an engine cycle?5.list the four engine strokes.6.how is displacement measured?7.how do you calculate compression ratio?汽车运用教研组 黄银娣 开发CH2:Engine fundamentalsth

26、e in-line engine （直列式） the V type engine （V形）a flat engine（平卧式）a flat engine（平卧式）cylinder arrangment汽缸的布置 形式front engine drive the rear wheel（前置后驱）front engine front wheel（前置前驱）front engine front wheel（前置前驱）rear engine rear wheel(后置后驱）engine placement发动机的位置engine configuration(发动机结构）21 Engine system

27、sfuel system燃 料 系 统intake system进 气 系 统ignition system点 火 系 统co o lin g sy ste m冷 却 系 统lu b rica tio n sy ste m润 滑 系 统e x h a u st sy ste m(排 气 系 统 ）engine systems(发 动 机 系 统 组 成 )22 Engine configuration the in-line engineThe way to arrange cylinders in a group is to line them up in a straight row.Us

28、ually have even number (four,six, eight line cylinders,its balanced.But sometime have 3or 5 cylinders.21：An example of an in-line engine that has four cylinders in a line.The V-type engineThe V-8 engine was designed to produce the power of the in-line eight in a smaller engine.Has two four-cylinder

29、in-line engines placed beside each other in the shape of a V Has only one crankshaft ,with all eight cylinders connected. In the United States,it was for years the moat popular engine. Today ,there are V-4 engine just two cylinder long ;V-6 type ;V-8,even some expensive foreign cars have V-12 engine

30、s,which have two bank of six cylinders each. 2-2: Auto manufactures make V-type engines of four, six, and eight cylinders. A V-6 configuration is shown here.2-3: the horizontally-opposed engine has two banks of cylinders pointing in opposite directions. Because the banks have a 180 angle between the

31、m, this engine is called a flat engine.The flat engine See Fig.2-3It has two banks of cylinders opposite one another .Just like the V-type become a flat horizontal line.Eg. Air-cooled Volkswagens(大众） use the flat-four engine. Many Porsches use the flat-six.23 Engine placement发动机驱动：发动机驱动：Front engine

32、,rear wheel drive(truck,jeep etc.)Rear engine,rear wheel drive(Passenger cars)Front engine,front wheel drive(most car)发动机位置发动机位置：In-line power train（纵向发动机）纵向发动机）:the engine is centered and the shafts run the length of the car.（与车轴垂直）Transverse engine(横向发动机）横向发动机）:the engine is crosswise in the car.

33、In this case ,the engine is right over the front axle. Which it drives. A car with such a design has a transverse engine.（与车轴平行)ABEngine Engine Drive shaft Driving axle Driving axle 2-4: (A)Many cars have an in-line engine arrangement with the engine and drive shaft running front-to-rear. (B)In tran

34、sverse engine arrangement the engine runs from side to side.24 The engine system the fuel systemAs show in Fig.2-5Function : the fuel system stores fuel and delivers it to the engine as needed.Composition:four basic parts make up the fuel system. They are the fuel tank ,fuel lines,fuel pumps and the

35、 fuel filter.1. The fuel tank is usually near the rear of the automobile. This tank holds from 10 to 25 gallons (38-95 liters) of gallon. 2. The fuel lines, which are small metal tubes or pipes, carry the fuel to the engine. 3. The fuel pump is a small mechanical or electrical device that moves gaso

36、line from the tank and pumps it through the fuel lines to the engine. 4. The fuel filter fits in the fuel line and removes rust or dirt from the gasoline. Fuel tankFuel lineFuel pumpFuel filter2-5: The fuel system stores the fuel and delivers it to the engine as needed.25The intake systemSee Fig.2-6

37、Function: takes fuel from the fuel system,mixes it with just the right amount of air, and then delivers it to the combustion chamber.Composition: the air cleaner, the air filter,the carburetor,the intake manifold, the intake parts etc. 1. The air cleaner: is on the top of the intake system. The air

38、cleaner takes in air and sends it to the rest of the intake system. 2.The air filter: is inside the air cleaner. It removes dirt and dust from the air. 3. The carburetor: is underneath the air cleaner. This device mixes air and fuel in the proportions needed for good combustion inside the engine. Th

39、e standard proportion for this fuel mixture is fifteen parts air to one part gasoline. This is written as an air-fuel ratio of 15:1. Some cars use a fuel-injection device instead of a carburetor. 4.the intake manifold : is underneath the carburetor. It has a series of tubes or passageways. These con

40、nect the carburetor to each of the engines cylinders. 5.the intake parts: are the openings in the cylinders to which the manifold tubes connect. Thus,each intake port gets the carburetor air-fuel mixture and carries it to the combustion chamber. The intake valve is at the combustion-chamber end of t

41、he intake port. Air cleanerAir filtercarburetorIntake manifoldblock2-6: the main parts of the intake system.26 The ignition system See fig.2-7Function: the ignition system ignites (or fires) the air-fuel mixture in the combustion chamber at just the right instant.this instant is at the end of the co

42、mpression stroke and the beginning of the power stroke. Unless the fuel is ignited at the correct moment,the engine will not run properly.Composition : battery,spark plugs, the coil, and the distributor etc. Coil wirebatteryCoil Spark plug wiresdistributorSpark plugs2-7: the ignition system takes el

43、ectricity from the battery and delivers it to the spark plugs to ignite the fuel-air mixture.1. The battery: change chemical energy to electrical energy. 2. The coil: is a small electrical device that increases the voltage of the electricity taken from the battery. The coil takes 12v from the batter

44、y and raises it to approximately 25000v. This is the amount of power needed to make a spark at the spark plug. 3. The distributor: takes this high-voltage electricity from the coil and “distributes” it to the right spark plug at the right time. 4. The spark plug cables: carry the electricity from th

45、e distributor to the spark plugs. 27 the cooling system See fig.2-8,2-9Function: to carry away the heat produced by the combustion engine inside the chamber.Types: a. the air-cooled engine（风冷发动机）(most motorcycle) b.and the water cooled engine （水冷发动机）(most cars)The water cooled:also called liquid-coo

46、led . a mixture of water and a chemical，the liquid prevents freezing in the winter and boiling in the summer. the chemical: is antifreeze (防冻剂）(its scientific name is ethylene glycol) airairfanCooling fins2-8: An air-cooled engine uses the outside air passing over the engine to carry away the heat p

47、roduced by the burning mixture.Water jacketWater pumpcoolantradiator2-9: A water-cooled engine uses a liquid to cool the engine. Then it uses air to cool the liquid.28The lubrication systemSee Fig.2-10,11Parts of the lubrication system :1.The oil pan (油底壳）: is the holder ,or sump ,for the 3-6qts.(ab

48、out 3-5L)of oil .2.an oil pump （油泵）:draws the oil from the pan and pushes it through the oil filter.3.the oil filter（滤清器）:removes dirt from the oil .4.oil galleries(油道）：passages the oil through in the engine parts that need lubrication.Pushing force force of friction 2-10 : friction is the force tha

49、t resists motion between two surfaces in contact. Oil galleries Oil pan Oil pick up Oil pump Oil filter2-11: the lubrication system provides oil to all internal engine parts, to reduce heat inside the engine. 29 The exhaust system(排气系统） Function:takes the burned gases from the cylinder,carries them

50、away from the engine,and discharges them into the air.See fig. 2-12Parts of the exhaust system: exhaust manifold （排气歧管）,exhaust pipe（排气管） ,intermediate pipe（中间排气管）,muffle（消声器）,and tail pipe（排气尾管） .Tail pipemufflerIntermediate pipeExhaust pipeExhaust manifold2-12: the exhaust system Carries the burne