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1、Unit 2-1Main Components of Engine,Contents,Pre-questions,II. Text Explanation,III. Exercises,Pre-questions,The heart of automobile,What impression of the engine?,complicated,power,Pre-questions,What are the types of the engine?electric motors, steam engines, and internal combustion engines Whats the
2、 internal combustion engine? burns fuel within the cylinders and converts the expanding force of the combustion into rotary force used to propel the vehicle.,Pre-questions,Words & phrases,Intake manifold mnfld 进气管throttle rt()l valve vlv 节气门Cylinder slnd head cover 气缸盖罩Distributor dstrbjt 分电器Cylinde
3、r cover 气缸盖Vent-pipe ventpaip 排气管Cylinder block 气缸体Spark plug plg 火花塞timing driving room cover 正时传动室盖Timing belt 正时齿轮带,Words & phrases,Camshaft kmft 凸轮轴Cam pulleypl 凸轮带轮Crankshaft krkft 曲轴Crankshaft timing belt gear wheel 曲轴正时齿形带轮Flywheel 飞轮Water jacket 水套Piston pst()n 活塞Sump smp 油底壳Mechanismmek()nz
4、()m 机械装置，原理Connecting rod 连杆lubricating lu:brikeiti system 润滑系统,Single-cylinder engine,cylinder,piston,Piston pin,Connecting rod,crankshaft,Oil pipe,Intake valve,Exhaust valve,Timing gear,Oil pump,what is the power source of automobile and how to produce?,piston,piston pin,connecting rod,crankshaft,
5、EnginePower is produced by the linear motion of a piston in a cylinder. The connecting rod transmits the up-and-down motion of the piston to the crankshaft, which changes it into rotary motion.,Pre-questions,The engine comprises two mechanism and five systems, what are they ?crankshaft and connectin
6、g rod mechanism（曲轴连杆装置）, valve gear (阀动装置）, cooling system, lubricating system, fuel system, starting system, ignition system,Pre-questions,9,connecting rod,flywheel,crankshaft,piston,intake valve,exhaust valve,push rod,tappet,timing gears, Valve gear Connecting rod,Engine cooling system,Engine lubr
7、icating system,Fuel supply system,Valve gear,pistoncrankshaftdistributorsumptiming gearcrankshaft and connecting rod mechanismvalve gearfuel systemSpark plugexhaust manifold,III. Exercises,Translate the following expressions into Chinese.,活塞曲轴分电器油底壳正时齿轮曲柄连杆机构配气机构燃油系统火花塞排气歧管,1-cylinder head cover 2-p
8、iston3-timing belt4-water pump5-sump6-oil pump7-crankshaft8-flywheel9-distributor10-valve,III. Exercises,Reading,How an Engine WorksThe internal combustion engine, as its name indicates, burns fuel within the cylinders and converts expanding force of the combustion into rotary force used to propel t
9、he vehicle. The actions taking place in the engine cylinder can be classified into four stages, or stroke. “stroke” refers to piston movement; a stroke occurs when the piston moves from one limiting position to the other. propel prpel v. 推动，驱动limiting position 极限位置,The internal combustion engine, as
10、 its name indicates, burns fuel within the cylinders and converts the expanding force of the combustion into rotary force used to propel the vehicle.译文：内燃机，顾名思义，就是燃料在气缸内部燃烧，并且把燃烧时的膨胀力转化为驱动车辆的旋转力。,II. Text Explanation,Convert.into.转变；变换That building has been converted into a school. 那座楼房改成学校了。兑换 I wa
11、nt to convert some Hong Kong dollars into American dollars. 我想把一些港元换成美元。改变信仰、党派或意见等 She managed to convert him to her opinion. 她终于设法说服了他接受她的意见。,II. Text Explanation,Reading,How an Engine Works. The actions taking place in the engine cylinder can be classified into four stages, or stroke.发动机气缸内的工作过程可
12、以分为四个过程或冲程。,be classified into.分类为、被分成Memory canbe classified intoshort-term and long-term memory.记忆可分为长期记忆和短期记忆。,II. Text Explanation,Reading,How an Engine Works“Stroke” refers to piston movement; a stroke occurs when the piston moves from one limiting position to the other. “冲程”指的是活塞的运动。当活塞从一个极限位置
13、移动到另一个极限位置，即完成了一次冲程。,Reading,The upper limit of piston movement is called TDC(top dead center). The lower limit of piston movement is called BDC(bottom dead center). A stroke is piston movement from TDC to BDC or from BDC to TDC. 活塞运动的上极限位置被称为TDC（上止点）。活塞的下极限位置被称为BDC（下止点）。一个冲程是指活塞从上止点运动到下止点或者从下止点运动到上
14、止点。,Reading,In other words, the piston completes a stroke each time it changes its direction of motion.换句话说，活塞每完成一次冲程就会改变运动方向。,In other words In other words, they remain relatively constant or static. 换句话说，它们相对的稳定、静止。 In other words, we have adhered to scientific socialism. 也就是说，我们坚持了科学社会主义,Reading,
15、Where the entire cycle of events in the cylinder requires four strokes (or two crankshaft revolutions), the engine is called a four-stroke-cycle engine. The four piston strokes are intake, compression, power and exhaust.气缸内的全部循环运动需要四冲程（或称为二次曲轴转动），这种发动机称为四冲程循环发动机。活塞的四冲程分别为进气行程、压缩行程、做功行程和排气行程。,Reading
16、,Intake stroke. On the intake stroke, the intake valve has opened, the piston is moving downward, and a mixture of air and vaporized gasoline is entering the cylinder through the valve port. The mixture of air and vaporized gasoline is delivered to the cylinder by the fuel system and carburetor.Vapo
17、rized veprazd adj. 汽化的carburetor ,kbjret n. 汽化器,Reading,On the intake stroke, the intake valve has opened, the piston is moving downward, and a mixture of air and vaporized gasoline is entering the cylinder through the valve port. “在进气行程中，进气门打开，活塞向下移动，可燃混合气通过进气门进入气缸。,Reading,The mixture of air and v
18、aporized gasoline is delivered to the cylinder by the fuel system and carburetor.适当浓度的可燃混合气是由燃料系统和化油器提供的。,Compression stroke. After the piston reaches BDC, or the lower limit of its travel. It begins to move upwards. As this happens, the intake valve closes. The exhaust valve is also closed, so that
19、 the cylinder is sealed. As the piston moves upward (pushed now by the revolving crankshaft and connecting rod), the air-fuel mixture is compressed to as little as one-tenth of its original volume, or even less. When the air-fuel mixture is compressed, not only does the pressure in the cylinder to u
20、p, but the temperature of the mixture also increases. revolving rvlv adj. 旋转的volumevljum n. 量,After the piston reaches BDC, or the lower limit of its travel. It begins to move upwards. As this happens, the intake valve closes. The exhaust valve is also closed, so that the cylinder is sealed. 在活塞到达下止
21、点时或者是活塞下限时，活塞开始向上运动。同时，进气门关闭，排气门也关闭，所以这时的汽缸是封闭的。,As the piston moves upward (pushed now by the revolving crankshaft and connecting rod), the air-fuel mixture is compressed to as little as one-tenth of its original volume, or even less. 当活塞向上运动时(这时是由转动的曲轴和连杆推动活塞)，可燃混合气被压缩。当活塞到达上止点时，可燃混合气被压缩到有原体积的十分之下
22、甚至更少。,When the air-fuel mixture is compressed, not only does the pressure in the cylinder to up, but the temperature of the mixture also increases.当油气混合燃料被压缩时，不仅汽缸里的压力上升，可燃混合气的温度也随之增加了。,Power stroke. As the piston reaches TDC on the compression stroke, and electric spark is produced at the spark plu
23、g. The ignition system delivers a high-voltage surge of electricity to the spark plug to produce the spark. The spark ignites the air-fuel mixture. It now begins to burn very rapidly, and the cylinder pressure increased to as much as 3-5MPa or even more. This terrific push against the piston forces
24、it downward, and a power impulse is transmitted through the connecting rod to the crankpin on the crankshaft. The crankshaft is rotated as the piston is pushed down by the pressure above it.,As the piston reaches TDC on the compression stroke, and electric spark is produced at the spark plug. The ig
25、nition system delivers a high-voltage surge of electricity to the spark plug to produce the spark. 当活塞到达压缩行程的上止点时，火花塞产生电火花。电火花是由点火系统向火花塞提供高压电脉冲而产生的。,The spark ignites the air-fuel mixture. It now begins to burn very rapidly, and the cylinder pressure increased to as much as 3-5MPa or even more. 电火花点
26、燃可燃混合气。可燃混合气开始发生剧烈燃烧，气缸内压力达到3-5兆帕，甚至更高。,This terrific push against the piston forces it downward, and a power impulse is transmitted through the connecting rod to the crankpin on the crankshaft. The crankshaft is rotated as the piston is pushed down by the pressure above it.作用于活塞上强大的推动力推动活塞向下运动，并将这一
27、推力通过连杆传到曲轴上的连杆轴颈上。因此，当活塞受压向下运动时，推动曲轴转动。,Exhaust stroke. As the piston reaches BDC again, the exhaust valve opens. Now, as the piston moves up on the exhaust stroke, it forces the burned gases out of the cylinder through the exhaust-valve port. Then, when the piston reaches TDC, the exhaust valve clo
28、sed and the intake valve opens. Now, a fresh charge of air-fuel mixture will be drawn into the cylinder as the piston moves down toward BDC.This four stroke cycle of piston within the cylinder is repeated time and again to put the vehicle forward.,As the piston reaches BDC again, the exhaust valve o
29、pens. Now, as the piston moves up on the exhaust stroke, it forces the burned gases out of the cylinder through the exhaust-valve port. 当活塞再一次到达下止点时，排气门打开。同时，活塞向上移动，把废气经排气门排出气缸。,Then, when the piston reaches TDC, the exhaust valve closed and the intake valve opens. Now, a fresh charge of air-fuel mi
30、xture will be drawn into the cylinder as the piston moves down toward BDC.随后活塞达到上止点，排气门关闭，进气门打开。当活塞又一次向下移动到达下止点时，新鲜燃混合气被吸入气缸。,This four stroke cycle of piston within the cylinder is repeated again and again to put the vehicle forward.上述的四个行程又继续重复，推进车辆前进。,stroke BDC TDC surge terrific crankpin intake
31、 strokeCompression stroke power stroke exhaust strokefresh charge,行程，冲程；上止点；下止点；冲击，脉动；了不起的，绝妙的；曲柄销，连杆轴颈；吸气冲程；压缩冲程；做功冲程；排气冲程；吸入的新鲜混合油气,I. Translate the following sentences into Chinese.1Engine is the power source of the automobile. Power is produced by the linear motion of a piston in a cylinder.发动机是
32、汽车的动力源.它通过汽缸内的活塞线性运动产生的.2The fuel system works according to the requirements of the engine as it provides an air-fuel mixture which must be in proportion to the speed and load placed on the engine.燃油系统的作用是根据发动机的转速和负荷提供一定比例的可燃混合气以满足发动机的需求。,III. Exercises,3The valve gear provides timely admission of t
33、he fresh charge into the cylinders and exhaust of spent gases from them.配气机构机构可定时的将新鲜气体充入气缸，并且将废气排放出去。,III. Exercises,1发动机主要有两大机构五大系统组成。An engine is mainly composed of two mechanisms and five systems.2曲柄连杆机构主要包括机体组，活塞连杆组和曲轴飞轮组。The crankshaft and connecting rod mechanism mainly consists of the engine
34、 crankcase and cylinder block, the piston and connecting rod, the crankshaft and flywheel.,III. Exercises,II. Translate the following sentences into English.,3水泵工作时，可以将冷却液在发动机水套中和散热器之间来回流动。When revolving, the water pump circulates coolant between the engine water jackets and the radiator.,III. Exercises,III. Exercises,Principle of Four-stroke Engine,1、intake stroke 2、compress stroke 3、power stroke 4、exhaust stroke,Intake valve,Exhaustvalve,Thank You !,
