汽车专业英语U1 L2（发动机部分）课件.ppt

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1、陈长梅,One.Crank-Connecting Rod MechanismCrank-connecting rod mechanism consists of piston-connecting rod group,crankshaft flywheel group,engine block group.,1The Engine Block Group（1）The Cylinder BlockThe cylinder block is the basic part of the engine.It forms the main framework or foundation of the e

2、ngine.Many parts of the engine are fixed to it.These items include water pump,oil pan,flywheel or clutch housing,ignition distributor,oil pump,fuel pump,and cylinder head.,（2）The Cylinder HeadThe cylinder head is bolted to the cylinder block.The top of the cylinder block is covered with the cylinder

3、 head which contains the combustion chamber（Fig.2-1）.,Single-cylinder engine,cylinder,piston,Piston pin,Connecting rod,crankshaft,Oil pipe,Inlet valve,Exhaust valve,Timing gear,Oil pump,connecting rod,flywheel,crankshaft,piston,inlet valve进水阀,exhaust valve,push rod,Tappet挺杆,timing gears,Valve gear阀装

4、置 Connecting rod,Engine Body,Crankcase曲轴箱,cylinder block,cylinder head,cylinder,oil passage and water passage油路和水路,oil pan,The cylinder gasket 气缸垫,3.cylinder gasket,2.cylinder head,1.Cylinder head cover,4.Pad 衬垫,5.to fit spark plug安装火花塞,Pre-questions,练 一 练,1-cylinder head cover;2-cylinder head;3-cyl

5、inder gasket;4-cylinder block;5-oil pan,油底壳,气缸垫,气缸体,气缸盖罩,气缸盖,Components of piston,piston top,piston head,piston skirt,活塞销孔,Piston pin hole,Small end小端,Connecting rod bushing连杆衬套,Connecting rod,Big end,Connecting rod half shells半壳,Connecting rod cap,compression rings,oil rings,piston pin,piston,conne

6、cting rod,crank bearing half shell曲柄轴承半壳,connecting rod cap,III.Exercises,2Crankshaft Flywheel Group（1）CrankshaftThe crankshaft is the main rotating shaft of the engine.Designed into the one-piece crankshaft are areas for main bearing journals,crankpins,counterweights,flywheel flange,and driving hub

7、.The crankshaft and connecting rod convert the reciprocating motion of the piston to the rotary motion of crankshaft.Crankshafts have drilled oil passages,through which oil can flow from the main bearings to the connecting-rod bearings.,（2）FlywheelThe flywheel is a comparatively heavy wheel,bolted t

8、o the flywheel flange on the rear end of the crankshaft.The inertia of the flywheel tends to keep it rotating at a constant speed.The flywheel also has several other functions,for example,the flywheel has ring gear in its outer circumference,which mesh with teeth located on the starting motor drive

9、pinion in order to crank the engine over.In addition,the rear surface of the flywheel serves as the driving member of the clutch assembly（Fig.2-2）.,Pre-questions,Whats the crankshaft assembly composed of?,crankshaft,Bearing轴承,timing gear,flywheel,belt pulley皮带轮,piston,3Piston-Connecting Rod Group（1）

10、The Connecting RodThe connecting rod links the piston to the crankshaft.The small end of connecting rod connects with the piston pin and the big end connects with the crank pin of the crankshaft.,（2）The PistonThe engine manufacturer fits a piston into each cylinder of the engine.The piston receives

11、the pressure from the burning air-fuel mixture and converts this pressure into up-and-down reciprocating motion.Because aluminum is half weight less than iron,most of pistons are made from aluminum alloy.（3）Piston RingsThe piston ring is a springy split metal ring.It is used to provide the necessary

12、 seal to eliminate blowby and to control oil consumption.Engine pistons have two kinds of rings：gas rings and oil rings.,The piston,Piston top,piston ring,piston pin,connecting rod,Two.The Valve Train,The valve train is a series of parts used to open and close the intake and exhaust valves.Meshing t

13、he timing gears or installing the timing chains onto the sprockets at a specific place will ensure the valves to open and close at the proper moment in the engines cycle.It consists of camshaft,tappet,pushrod,rocker arm,valve spring,valve and so on（Fig.2-4）.,1Camshaft The camshaft is another rotatin

14、g shaft within the engine,its driven by the engines crankshaft through the timing gears.The camshaft has a series of cams that can change rotary motion to straight-line motion which cause the intake valves and exhaust valves to open.It rotates at the half speed of the crankshaft.,2Tappet,Pushrods an

15、d Rocker ArmsTappet rests on a cam of the camshaft.The pushrod is a metal rod that fits between the tappet and the rocker arm.Its function is to transmit cam lobe lift to the rocker arm assembly.The rocker arm is nothing more than a lever.Its function is to convert the up wardmotion of a pushrod int

16、o downward motion that compresses the spring and opens the valve.,3Valves and Valve SpringsModern engines have cylinder heads that contain valves.Each cylinder requires at least two valves：an intake valve and an exhaust valve.The valves are compressed and closed by valve springs.As the valve is open

17、ed by the camshaft,it compresses the valve spring.,valves,rocks,push rods,tappets,camshaft,Words Phrases（单词和短语）,Pre-questions,What is regarded as the“backbone”of the engine and why?Crankshaft,because it can change the reciprocating motion(往复运动)of the piston into rotary(旋转)motion and handle(处理)the en

18、tire(全部)power output.,Regard as-译为：被叫做-,Pre-questions,Whats the function of the flywheel?helping the engine to run smoothly(平稳)during the power stroke and releasing(释放)it during the other strokes；carrying the clutch,which transmits(传输)the drive to the gearbox；has the starter ring gear，around its.,功

19、能,Pre-questions,Where is the flywheel in the engine?the rear of the crankshaft.,the starter ring gear,起动环形齿轮,Pre-questions,What is the function of the valve gear in an internal combustion engine?Open the inlet valve in time and let the air-fuel mixture into the cylinders in inlet stroke.Open the exh

20、aust valve in time and let the exhaust gases out of the cylinder in exhaust stroke.,Pre-questions,What does the valve gear of an internal combustion engine consist of?,rocks,push rods,tappets,camshaft,spring,valves,Pre-questions,Which component drives the camshaft?crankshaft,tension gear,crankshaft

21、timing gear,camshaft timing gear,Timing gear-belt,Pre-questions,What is the function of the valve spring?The valve spring provides(提供)the force(力量)necessary(必要的)to close the valve and hold(控制)it tightly(紧紧地)against(依附着)its seat(底座).,camshaft,camshaft,piston,spring,Piston pin,valve,Connecting rod,II.

22、Text Explanation,In an internal combustion engine,the valve gear provides timely admission of the air-fuel mixture into the cylinders and exhaust of the gases from them.internal combustion engine:内燃机admission-into：将-吸入-里译文：在内燃机中，配气机构能定时地将新鲜的混合气充入气缸，并且将废气从气缸中排出。,II.Text Explanation,internal combustio

23、n engine 内燃机 valve gear 配气机构 timely 及时的，适时的 fresh charge 新鲜混合气 air-fuel mixture 燃油混合气,II.Text Explanation,The valve gear is composed of timing gears,camshaft,tappets,push rods,rocks,valves,valve seats,spring with fasteners and valve guides.be composed of 由组成 tappet 挺杆 fastener 紧固件 valve guide 气门导管,V

24、alve,Function(作用)Open a passage,when moving in one direction(方向),and to close it when moving in the oppositepzit（相反的；）direction.,valve head,stem,III.Exercises,1-rocks2-valve spring3-valve guide4-valve5-valve seat6-camshaft7-tappet8-push rod,翻 译：,1、Most engines had two valves for each cylinder,one is for the inlet and the other for the exhaust.译：许多发动机的每个气缸都有两个气 门，一个是进气门、一个是排气门。,4、The valves are located within the cylinder head on most engines designed today.are located within 被安装在-里面；designed adj.有规则的，规矩的；译：气门被有规则的安装在汽缸头部里面。,Practice:P15.E x:1-2,Thank You!,