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1、.wd.wd.wd. hCHAPTER 1 AUTOMOTIVE BASICS 汽车原理1.1 Principal Components1.1 汽车主要组成局部Todays average car contains more than 15,000 separate, individual parts that must work together. These parts can grouped into four major categories: engine, body, chassis and electrical equipment.现代汽车有超过15000个零件组成,分成几个必须
2、在一起工作的功能局部。主要包括4个功能局部:引擎,车身,底盘和电控。1.2 Engine1.2引擎The engine acts as the power unit. The internal combustion engine is most common: this obtains its power by burning a liquid fuel inside the engine cylinder. There are two types of engine :gasoline(also called a spark-ignition engine) and diesel(also
3、called a compression-ignition engine).Both engines are called heat engines; the burning fuel generates heat which causes the gas inside the cylinder to increase its pressure and supply power to rotate a shaft connected to the transmission.引擎为汽车提供能源。一般是内燃机:通过在引擎缸内燃烧液体燃料获得能量。引擎有两种:汽油机和柴油机。两种引擎都叫热机。燃烧的
4、燃料产生大量大热,热量使缸内的气体产生大的压力,通过连杆使曲轴旋转。1.3 Body1.3 车身An automobile body is a sheet metal shell with windows, doors, a hood, and a trunk deck built into it. It provides a protective covering for the engine, passengers, and cargo. The body is designed to keep passengers safe and comfortable. The body styli
5、ng provides an attractive, colorful, modern appearance for the vehicle.车身有窗户,门,盖,内饰等组成,它为发动机,乘客及货物提供空间和保护。车身的设计要让乘客安全并乘坐舒适。对于乘用汽车,车身要动感,色彩绚丽,现代化。1.4 Chassis1.4 底盘The chassis is an assembly of those systems that are the major operating part of a vehicle. The chassis includes the transmission, suspens
6、ion, steering, and brake systems.底盘是一个组合体,主要由汽车的操纵局部,传动系统,悬架,转向局部,制动系统组成。Transmission systems conveys the drive to the wheels. The main components are clutch, gearbox, driveshaft, final drive, and differential.传动系统用来驱动车轮。主要有离合器,变速箱,驱动轴,最后驱动和差速器组成。Suspension absorbs the road shocks.悬架主要用来吸收路面冲击。Steer
7、ing controls the direction of the movement.转向系统控制汽车的行驶方向。Brake slows down the vehicle.制动系统使汽车停下来。1.5 Electrical EquipmentThe electrical system supplies electricity for the ignition, horn, lights, heater, and starter. The electricity level is maintained by a charging circuit. This circuit consists of
8、 the battery, alternator (or generator). The battery stores electricity. The alternator changes the engines mechanical energy into electrical energy and recharges the battery.电动系统主要为点火系统,喇叭,灯,加热器,及启动系统提供电能。电压通过一个电路保持恒定。这个电路有电池,发电机组成。电池储存电能,发电机把引擎的机械能转化为电能,给电池充电。New WordsPrincipal component 主要部件categ
9、ory 种类,类型body 车身chassis 底盘layout 布置power unit 动力装置internal combustion engine 内燃机cylinder 汽缸gasoline 汽油spark 火花ignition 点燃,点火diesel 柴油机compression 压缩shaft 轴transmission 传动系sheet metal 金属板shell 外壳hood 发动机罩trunk deck 行李舱盖cargo 货物styling 样式assembly 总成,装配suspension 悬挂,悬置shock 冲击steering 转向,操纵brake 刹车,制动器
10、clutch 离合器gearbox 变速器driveshaft 传动轴final drive 主减速器,后桥differential 差速器slow down 使慢下来,减速horn 喇叭starter 起动机charge 充电alternator 交流发电机Review QuestionsList the main parts of an automobile?汽车的主要局部有哪些What are the common types of a vehicle according to body styling?根据车身,汽车的一般类型有哪些Which systems does a chassi
11、s include and what are the main functions of the chassis?汽车底盘有哪些系统,底盘的功用是那些Why are suspension systems used on vehicles?汽车为什么用悬架系统CHAPTER2 INTERNAL COMBUSTION ENGINE第二章 引擎燃烧室2.1 principle of operation 2.1原理2.1.1 Engine and power 2.1.1引擎和能量 Engine is used to produce power. The chemical energy in fuel
12、is converted to heat by the burning of the fuel at a controlled rate. This process is called combustion. If engine combustion occurs with the power chamber. ,the engine is called internal combustion engine. If combustion takes place outside the cylinder, the engine is called an external combustion e
13、ngine.引擎为汽车提供能量,燃料的化学能通过燃烧,转化为热能,这个过程叫燃烧。假设燃烧在燃烧室,这样的发动机叫内燃机。假设燃烧在气缸外,这样的发动机叫外燃机。 Engine used in automobiles are internal combustion heat engines. Heat energy released in the combustion chamber raises the temperature of the combustion gases with the chamber. The increase in gas temperature causes th
14、e pressure of the gases to increase. The pressure developed within the combustion chamber is applied to the head of a piston to produce a usable mechanical force, which is then converted into useful mechanical power.用在汽车上的一般是内燃机,热能在燃烧室释放,燃烧室气体温度升高。气体温度的升高使气体的压力曾加,燃烧室内的高压气体作用在活塞头部产生可以利用的化学能,化学能转化为机械能
15、。2.1.2 Engine Terms 2.2.1引擎冲程 Linking the piston by a connecting rod to a crankshaft causes the gas to rotate the shaft through half a turn. The power stroke “uses up the gas , so means must be provided to expel the burnt gas and recharge the cylinder with a fresh petrol-air mixture :this control of
16、 gas movement is the duty of the valves ;an inlet valve allows the new mixture to enter at the right time and an exhaust valve lets out the burnt gas after the gas has done its job. Engine terms are :连接活塞和曲轴的连杆,是气体推动曲轴旋转的原因。做功冲程利用气体,也就意味着吧废气排出缸体,同时燃烧室吸入新鲜的燃油和空气:这个功能是气门的职责;进气门使新鲜的混合气在适宜的时刻进入,排气门使燃烧过的
17、混合气排除缸外。 TDC(Top Dead Center):the position of the crank and piston when the piston is farther away from the crankshaft.上止点:当活塞离曲轴最远时,活塞或曲轴的位置。 BDC(Bottom Dead Center):the position of the crank and piston when the piston is nearest to the crankshaft.下止点:当活塞距离曲轴最近时,活塞或曲轴的位置。 Stroke : the distance betw
18、een BDC and TDC; stroke is controlled by the crankshaft.冲程:上止点和下止点的距离;冲程被曲轴控制。Bore : the internal diameter of the cylinder.缸经:缸筒的内经。 Swept volume : the volume between TDC and BDC. 有效容积:上止点和下止点直接的容积。 Engine capacity : this is the swept volume of all the cylinder e.g. a four-stroke having a capacity o
19、f two liters(2000cm) has a cylinder swept volume of 50cm. 发动机的排量:指发动机所以缸的排量,一个四冲程2升发动机每个气缸的排量是50. Clearance volume: the volume of the space above the piston when it is at TDC. 燃烧室:当活塞在上止点时,活塞上面的容积。 Compression ratio = (swept vol + clearance vol)(clearance vol) 压缩比=有效容积+燃烧室容积燃烧室容积 Two-stroke : a powe
20、r stroke every revolution of the crank. 两冲程发动机:曲轴旋转一周,一个做功冲程。 Four-stroke : a power stroke every other revolution of the crank. 四冲程发动机:曲轴旋转两圈,一个做功冲程。2.1.3 The Four-stroke Spark-ignition Engine Cycle2.1.3四冲程发动机的点火系统 The spark-ignition engine is an internal-combustion engine with externally supplied i
21、n ignition , which converts the energy contained in the fuel to kinetic energy.四冲程点火发动机是一个具备外部点火系统的把燃料的能量转化为机械能的机械。 The cycle of operations is spread over four piston strokes. To complete the full cycle it takes two revolutions of the crankshaft. 一个循环包括四个冲程。每个循环曲轴要旋转两圈。The operating strokes are :吸气冲
22、程:This stroke introduces a mixture of atomized gasoline and air into the cylinder. The stroke starts when the piston moves downward from a position near the top of the cylinder. As the piston moves downward, a vacuum, or low-pressure area, is created. During the intake stroke, one of the ports is op
23、ened by moving the inlet valve. The exhaust valve remains tightly closed.吸气冲程吧雾化的汽油和新鲜空气吸入缸内。吸气冲程开场时,活塞在上止点。当活塞向下运动时,产生真空和低压,混合气体被吸入。在吸气冲程,进气门翻开,排气门闭合。Compression stroke压缩冲程As the piston moves upward to compress the fuel mixture trapped in the cylinder, the valves are closed tightly. This compressio
24、n action heats the air/fuel mixture slightly and confines it within a small area called the combustion chamber.当活塞向上运动时,气门紧闭,活塞压缩混合可燃气。压缩混合气在燃烧室温度升高。Power stroke做功冲程Just before the piston reaches the top of its compression stroke, an electrical spark is introduced from a spark plug screwed into the
25、cylinder head.The spark ignites the compressed, heated mixture of fuel and air in the combustion chamber to cause rapid burning. The burning fuel produces intense heat that causes rapid expansion of the gases compressed within the cylinder. This pressure forces the piston downward. The downward stro
26、ke turns the crankshaft with great force.在活塞到达压缩冲程的上止点前,缸盖上螺纹固定的火花塞产生火星,点火。火花点燃在燃烧室高压高温的燃油混合气体使其快速燃烧。快速燃烧的燃气产生大量的热,在缸体内迅速扩散产生压力。高压气体推动活塞向下运动。向下的运动使曲轴旋转。Exhaust stroke排期冲程Just before the bottom of the power stroke, the exhaust valve opens. This allows the piston, as it moves upward, to push the hot,
27、burned gases out through the open exhaust valve.Then, just before the piston reaches its highest point, the exhaust valve closes and the inlet valve opens. As the piston reaches the highest point in the cylinder, known as TDC, it starts back down again. Thus, one cycle ends and another begins immedi
28、ately.在做工冲程即将完毕时,排气门翻开。活塞向上运动,将热燃烧后的混合气通过排气门排除缸体外。在活塞到达上止点前排气门关闭,进气门开启。当活塞到达所谓的上止点时,活塞又开场向下运动,这样一个循环完毕,另一个循环开场。2.1.4 Engine Overall Mechanics2.1.4 发动机的总体构造 The engine has hundreds of other parts . The major parts of engine are engine block , engine heads, pistons, connecting rods, crankshaft and val
29、ves. The other parts are joined to make systems. These systems are the fuel system, intake system, ignition system, cooling system, lubrication system and exhaust system. Each of these systems has a definite function. These systems will discussed in detail later. 发动机有说百个部件,发动机的主要部件是缸体,缸盖,活塞,连杆,曲轴和气门
30、。其它局部组合成系统,这些系统包括,燃油供应系统,进气系统,点火系统,冷却系统,润滑系统,和排气系统。每个系统都有一定的功能。这些系统将在以后的的章节详细讨论。NEW WORDPiston 活塞Connecting rod 连杆Crankshaft 曲轴Power stoke 活塞行程Expel 排出Valve 气阀inlet(intake) valve 进气阀exhaust valve 排气阀term 术语TDC 上止点BDC 下止点Bore 缸径swept volume 有效容积engine capacity 发动机排量clearance volume 余隙容积,燃烧室容积compress
31、ion ratio 压缩比revolution 旋转,转数every other 每隔一个cycle 循环spread over 分布,普及intake stroke 进气行程 compression stroke 压缩行程knock 敲缸,敲打exhaust stroke 排气行程engine block 发动机缸体lubrication 润滑2.2 Engine Block and Cylinder Head2.2发动机缸体和缸盖2.2.1 Engine Block2.2.1缸体The engine block is the basic frame of the engine. All o
32、ther engine parts either fit inside it or fasten to it. It holds the cylinders, water jackets, and oil galleries. The engine block also holds the crankshaft, which fastens to the bottom of the block. The camshaft also fits inside the block, except on overhead-cam engines (OHC). In most cars, this bl
33、ock is made of gray iron, or an alloy (mixture) of gray iron and other metals, such as nickel or chromium. Engine blocks are castings.缸体是发动机的根基,其它的部件要么装在缸体内,要么固定在缸体上。水套和油道在缸体内。当然缸体也固定曲轴,曲轴固定在缸体的底部。凸轮轴也固定在缸体上,除非是顶置凸轮轴固定在缸盖上。在大多数汽车上,缸体的材料是灰铸铁或者是灰铸铁和其它金属的合金,例如镍镉合金,缸体是铸件。Some engine blocks, especially t
34、hose in smaller cars, are made of cast aluminum. This metal is much lighter than iron. However, iron wears better than aluminum. Therefore, the cylinders in most aluminum engines are lined with iron or steel sleeves. These sleeves are called cylinder sleeves. Some engine blocks are made entirely of
35、aluminum.一些发动机缸体,特别是小汽车缸体是铸铝。这种金属比铸铁轻。虽然,铸铁的耐久性比驴占优势。因此,铝合金缸体的气缸被镶上铸铁或钢质圆桶,那些桶被叫做缸套。还有一些发动机全部是铝缸体。2.2.2 Cylinder Head2.2.2缸盖The cylinder head fastens to the top of the block, just as a roof fits over a house. The underside forms the combustion chamber with the top of the piston. The most common cyli
36、nder head types are the hemi, wedge, and semi-hemi. All three of these terms refer to the shape of the engines combustion chamber. The cylinder head carries the valves, valve springs and the rockers on the rocker shaft, this part of the valve gear being worked by the push-rods. Sometimes the camshaf
37、t is fitted directly into the cylinder head and operates on the valves without rockers. This is called an overhead camshaft arrangement. Like the cylinder block, the head is made from either cast iron or aluminum alloy.缸盖固定在缸体上,就像房子的屋顶。缸盖下面空间和活塞形成燃烧室。一般气缸盖的燃烧室是半球形,楔形,半独立燃烧室。三种燃烧室形状都影响发动机燃烧室。缸盖上安装气门,
38、气门弹簧和气门摇臂,这个气门通过推杆工作。有时候,缸盖上的凸轮轴不经过摇臂直接气门。被叫做顶置凸轮轴构造。就像缸体,缸盖的材料是铸铁或铸铝。2.2.3 Gasket2.2.3气缸垫The cylinder head is attached to the block with high-tensile steel studs. The joint between the block and the head must be gas-tight so that none of the burning mixture can escape. This is achieved by using cyl
39、inder head gasket. This is a sandwich gasket, i.e. a sheet of asbestos between two sheets of copper, both these materials being able to withstand the high temperature and pressures within the engine.缸盖被高强度螺钉固定在缸体上。在缸体和缸盖的结合处有耐气的垫片,防止燃烧的混合气体外溢。缸垫可以实现这一功能。气缸垫就像是三明治,一层石棉夹在铜材料的中间,这两种材料都能承受发动机高温和高压。2.2.4
40、 Oil Pan or Sump2.2.4油底壳The oil pan is usually formed of pressed steel. The oil pan and the lower part of the cylinder block together are called the crankcase; they enclose, or encase, the crankshaft. The oil pump in the lubricating system draws oil from the oil pan and sends it to all working parts
41、 in the engine. The oil drains off and runs down into the pan. Thus, there is constant circulation of oil between the pan and the working parts of the engine.油底壳一般是钢铁冲压件,油底壳和缸体下面局部被叫做曲轴箱,它们把曲轴密封,包裹起来。润滑系统的油泵吸取油底壳的油输送到发动机的工作局部润滑。油流经油道又回到油底壳。这样,机油在发动机工作局部和油底壳之间始终有一个连续的循环。New Wordsengine block 缸体cylind
42、er head 气缸盖fasten 使固定water jacket 水套oil gallery 油道camshaft 凸轮轴overhead-cam(OHC) 顶置凸轮gray iron 灰铸铁alloy 合金nickel 镍chromium 铬casting 铸件head cover 汽缸盖罩intake manifold 进气总管distributor 分电器oil pan 油底壳aluminum 铝be lined with 镶有cylinder sleeve 气缸套hemi 半球形wedge 楔型,楔入semi-hemi 准半球形rocker 摇臂push-rod 推杆gasket 衬
43、垫high-tensile 高强度的stud 螺栓gas-tight 密封的asbestos 石棉crankcase 曲轴箱,曲柄箱encase 封闭,把包起来drain off 排出,流出Review Question问题回忆What do TDC, BDC, stroke, compression ratio and engine capacity stand for?1.TDC,BDC冲程,压缩比,引擎排量是什么意思How do you calculate swept volume and compression ratio?2.若何计算排气容积及压缩比What controls the
44、 length of the stroke?3.行程是若何控制的List the main parts of the engine overall mechanics?4.说出发动机的主要局部What are the main function of the engine block?5.缸体的作用是什么2.3 Piston Connecting Rod and Crankshaft2.3活塞连杆和曲轴2.3.1 Piston Assembly 2.3.1活塞总成 The piston is an important part of a four-stroke cycle engine. Mo
45、st pistons are made from cast aluminum. The piston , through the connecting rod, transfers to the crankshaft the force create by the burning fuel mixture. This force turns the crankshaft .Thin, circular , steel bands fit into grooves around the piston to seal the bottom of the combustion chamber. Th
46、ese bands are called piston rings. The grooves into which they fit are called ring grooves. A piston pin fits into a round hole in the piston . The piston pin joins the piston to the connecting rod . The thick part of the piston that holds the piston is the pin boss.活塞是四冲程发动机的一个重要部件。大多数的活塞是铝合金浇注而成。活
47、塞通过连杆把燃烧混合气体的能量传给曲轴。这种能量使曲轴旋转,薄的,圆筒钢片安装在活塞队环槽内来密封燃烧室的底部。这些薄片叫做活塞环。活塞上的槽被叫做活塞环槽。活塞销装在活塞的圆孔内。活塞销吧活塞和连杆链接起来。用来支撑活塞销厚道活塞局部叫活塞销凸台。The piston itself , its rings and the piston pin are together called the piston assembly. 活塞和活塞销在一起被叫做活塞总成。2.3.2.Piston2.3.2活塞To withstand the heat of the combustion chamber,
48、the piston must be strong. It also must be light, since it travels at high speeds as it moves up and down inside the cylinder. The piston is hollow. It is thick at the top where it take the brunt of the heat and the expansion force. It is thin at the bottom, where there is less heat. The top part of
49、 the piston is the head , or crown . The thin part is the skirt The sections between the ring grooves are called ring lands.为了能承受燃烧室的热量,活塞必须有一定的强度。活塞要轻,因为它以很高的速度在缸体里上下运动。因此,活塞是空的。活塞的头部很厚,因为,活塞头部要承受燃烧和膨胀的热量。活塞底部很薄,因为那里几乎没有热。活塞的顶部叫做活塞顶或活塞头。活塞的薄局部叫活塞裙部。The piston crown may be flat , concave ,dome or re
50、cessed . In diesel engine , the combustion chamber may be formed totally or in part in the piston crown , depending on the method of injection . So they use pistons with different shapes.活塞头可能是平的,凹的,圆的。在柴油机中,今天活塞头是组成燃烧室的一局部,这取决于喷射的方式。所以,柴油机活塞有的形状很自由。2.3.3Piston Rings2.3.3活塞环As Fig.2-9 shows , piston
51、 rings fit into ring grooves near the of the piston. In simplest terms, piston rings are thin, circular pieces of metal that fit into grooves in the tops of the pistons. 正像2-9所展示的,活塞环装在活塞顶部的的活塞环槽里。一般的活塞环是薄的,圆环金属片,正好贴在活塞头部的活塞环里。In modern engines ,each piston has three rings. (Piston in older engines
52、sometimes had four rings, or even five.) The rings outside surface presses against the cylinder walls. Rings provide the needed seal between the piston and the cylinder walls. That is, only the rings contact the cylinder walls. The top two rings are to keep the gases in the cylinder and are called c
53、ompression rings. The lower one prevents the oil splashed onto the cylinder bore from entering the combustion chamber , and is called an oil ring. Chrome-face cast-iron compression rings are commonly used in automobile engines. The chrome face provide a very smooth , wear-resistant surface.现代发动机,每个活
54、塞都有三个活塞环近代发动有时候有四个活塞环,甚至五个。活塞环的外外表贴在缸筒的壁面上。活塞环在活塞和缸筒之间形成密封。也就是说,只有活塞环和岗壁接触。活塞上面的两道环使气体早缸筒里,叫做气环。第三道环使机油流回阻止机油进入燃烧室,被叫做油环。ring the power stoke , combustion pressure on the combustion rings is very high. It causes them to untwist . Some of the high-pressure gas gets in back of the rings. This force th
55、e ring face into full contact with the cylinder wall. The combustion pressure also holds the bottom of the ring tightly against the bottom of the ring groove. Therefore , high combustion pressure causes a tighter seal between the ring face and the cylinder wall.做工冲程中,燃烧室里气环的压力很高。压力使气环错开。一些高压气体进入气环背隙
56、。这样使气环完全和缸壁接触。燃烧压力当然使气环的底部紧紧的贴在活塞环槽里。因此,高的压力使活塞环在缸体和活塞间形成了密封。2.3.4 Piston Pin 2.3.4活塞销The piston pin holds together the piston and the connecting rod . This pin fits into the piston pin holes and into a hole in the top end of the connecting rod. The top end of is much smaller than the end that fits
57、on the crankshaft . This small end fits inside the bottom of the piston . The piston pin fits through one side of the piston , through the small end of the rod , and then through the other side of the piston . It holds the rod firmly in place in the center of the piston. Pins are made of high-streng
58、h steel and have a hollow center . Many pins are chrome-plated to help them wear better.活塞销连接活塞和连杆。活塞销要穿进活塞销空和连杆小头。连杆头部的孔比连杆和曲轴链接的孔小,连杆小头安装活塞底内部。活塞销通过活塞孔,连杆小头孔,活塞的另一侧销孔。销使连杆紧紧的固定在活塞中间。活塞销是高强度金属制成,并且是空心的。许多活塞销镀烙提高其耐磨性。2.3.3 Connecting rod 2.3.3连杆The connecting rod is made of forged high-strength stee
59、l . It transmits and motion from the piston to the crankpin on the crankshaft . The connecting rod little end is connected to the piston pin . A bush made from a soft metal , such as bronze , is used for this joint . The lower end of the connecting rod fits the crankshaft journal . This is called th
60、e big end . For this big-end bearing , steel-backed lead or tin shell bearing are used . These are the same as those used for the main bearings . The split of the big end is sometimes at an angle , so that it is small enough to be withdrawn through the cylinder bore . The connecting rod is made from
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