汽车发动机车身全系列专业英语.docx

It is well-known that the automobile is composed of four sections such as engine, chassis, body and electrical system. 众所周知，汽车都由发动机、底盘、车身以及电气系统四部分组成。 The engine which is called the "heart" of a vehicle is used to supply power for an automobile. It includes the fuel, lubricating, cooling, ignition and starting systems. Generally, an automobile is operated by internal combustion engine. The internal combustion engine burns fuel within the cylinders and converts the expanding force of the combustion or "explosion" into rotary force used to propel the vehicle. 发动机是汽车的心脏，向汽车提供动力。它包含有燃料系统、润滑系统、冷却系统、点火系统和起动系统。汽车一般采用内燃发动机。内燃发动机在汽缸里燃烧燃料将内燃所产生的膨胀力转变成旋转力，用以推动车辆前进。 The chassis is a framework used to assemble auto components on it. The chassis itself is divided into four systems like transmission system, suspension system, steering system and brake system. 底盘是一个用以总装汽车部件的框架。底盘本身可以分成四个系统，即传动系统、悬架系统、转向系统和制动系统。 The transmission system applies to the components needed to transfer the drive from the engine to the road wheels. The main components are clutch, gearbox, drive shaft, final drive and differential. 传动系统运用所需部件将发动机产生的动力传递到车轮。它的主要部件有离合器、变速器、传动轴、 后桥和差速器。 The primary purpose of the suspension system is to
undefined
increase strength and durability of components and to meet customers' requirements for riding comfort and driving safety. In automobile suspension, the major component is springs. The springs used on today's vehicles are engineered in a wide variety of types, sizes, rates and capacities. Spring types include leaf springs, coil springs and torsion bars. Springs are paired off on vehicles in various combinations, and are attached to vehicle by different mounting techniques. 悬架系统的主要目的是提高零部件的强度和寿命，并满足顾客对车辆乘坐舒适性和驾驶安全性的需求。汽车悬架上的主要部件是弹簧。在当今车辆上使用的弹簧被设计制造成许多不同的型号、大小、标准及负载。弹簧类型包括钢板弹簧、螺旋弹簧和扭力弹簧。弹簧以各种组合形式在车辆上配套使用，并用不同的装配技术将弹簧装在车辆上。 The function of the steering system is to provide the driver with a means for controlling the direction of the vehicle as it moves. The steering system consists of steering wheel, steering shaft, worm, gear sector, pitman arm, drag link, steering knuckle arm, king pin, steering arms, tie rod, front axle and steering knuckle. They enable the car to change the direction by means of turning and moving forth and back. 转向系统的用途是在驾驶员的操纵下控制汽车行驶的方向。转向系统包括转向盘、转向轴、蜗杆、扇形齿轮、转向摇臂、直拉杆、转向节臂、主销、转向臂、转向横拉杆、前轴和转向节。这些零部件前后移动或转动，可以使汽车改变运动方向。 The automobile brake system is a friction device to change power into heat. When the brakes are applied, they convert the power of momentum of the

moving vehicle {kinetic energy) into heat by means of friction, thus retarding the motion of the vehicle. Structurally, an automotive brake system contains these major parts like brake drum, brake shoe, brake lining, etc. Functionally, an automotive brake system can be divided into wheel brake mechanism and parking brake mechanism. 汽车制动系统是一种将动力转变为热量的摩擦装置。当使用制动器时，制动器通过摩擦将行驶车辆的动量力转变成热量，从而使车辆运动停滞。从结构上讲，汽车制动系含有几个主要部件，如制动鼓、制动蹄片、制动器摩擦衬片等。从功能上讲，汽车制动系可分为行车制动机构和停车制动机构。 The automobile body serves the obvious purpose of providing shelter, comfort and protection for the occupants. The body is generally classified into four sections: the front, the rear, the top and the underbody. These sections can further fall into a lot of assemblies and parts, such as the hood, the fenders, the roof panels, the door, the instrument panel, the bumpers and the luggage compartment. 车身的基本功能就是向乘员提供保护，使其乘坐舒适并保证安全。车身一般分为四个部分:车前部、车后部、车顶部和车下部。这些部分可以进一步分为许多的分总成和部件，如发动机盖板、 挡泥板、车身顶板、车门、仪表板、汽车保险杠和行李箱。 The electric system supplies lighting and driving power for the automobile. It cranks me engine for starting. It supplies the high-voltage surges that ignite the compressed air-fuel mixture in the combustion chambers. The electric system includes the battery, generator, starting system, ignition system, lighting system, horn system, radio and other devices. 电气系统向汽车提供照明

与驱动电力。它能起动发动机、提供高压电脉冲点燃燃烧室中空气和燃油的高压混合气等。电气系统包括电池、发电机、起动系统、点火系统、照明系统、喇叭、收音机以及其他装置。 The auto description above seems to conclude that though automobiles are quite different in design, they are basically similar in structure. 综上所述，尽管汽车的设计变化很大，然而汽车的构造基本上是一样的。 Text Four-stage-engine Operation There are various types of engines such as electric motors, steam engines and internal combustion engines. But, the internal combustion engine seems to be the one most commonly used in the automotive field. According to the fuel energy used, internal combustion engines are further divided into gasoline engines, kerosene engines, diesel engines, etc. 四行程发动机工作过程 发动机有各种各样的类型，如电动机、蒸汽机和内燃机。但是，在汽车领域里内燃机似乎是 用得最为普遍的发动机。根据所用燃料，内燃机还可分为汽油机、煤油机、柴油机等。 The internal combustion engine, as its name indicates, burns fuel within the cylinders and converts the expanding force of the combustion into rotary force used to propel the vehicle. The actions taking place in the engine cylinder can be classified into four stages, or strokes. "Stroke" refers to piston movement; a stroke occurs when the piston moves from one limiting position to the other. 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. In other words, the piston completes a stroke each time it changes its direction of motion. 顾名思义，内燃发动机是在汽缸里燃烧燃料，将内燃的膨胀力转变成推动汽车前进的旋转力。发动机汽缸内的工作过程可以分为四个过程或行程。(冲程)行程是指活塞的运动，即活塞从某一限定位置到另一限定位置的运动。活塞运动的上限称为TDC(上止点)，下限称为BDC(下止点)。一个行程就是活塞从上止点到下止点，或从下止点到上止点的运动。换句话说，活塞每完成一个行程， 就改变一次其运动的方向。 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-stroke-cycle engine is also called the Otto cycle engine, in honor of the German engineer, Dr. Nikolaus Otto , who first applied the principle in 1876. The four piston strokes are intake, compression, power and exhaust. 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. Compression stroke. After the piston reaches BDC, or the lower limit of its travel, it begins to move upward. As this happens, the intake valve closes. The exhaust valve is also closed, so that the cylinder is sealed. As the piston moves upward (pushed now by the revolving crankshaft and connecting rod), the air-fuel mixture is compressed. By the time the piston reaches TDC, the mixture has been 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 up, but the temperature of the mixture also increases. Power stroke. As the piston reaches TDC on the compression stroke, an electric spark is produced at the spark plug. 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 bum very rapidly, and the cylinder pressure increases to as much as 3~5MPa or even more. 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. 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 closes and the intake valve opens. Now, a fresh charge of air-fuel mixture will be drawn in to the cylinder as the piston moves down again toward BDC. This four stroke cycle of piston within the cylinder is repeated time and again to put the vehicle forward. 发动机汽缸中的全部工作过程分为四个冲程的(即曲轴旋转两周的)，叫做四冲程循环发动机，或四循环发动机。为纪念德国工程师尼科拉斯、奥托搏士于1876年首次运用四行程循环原理，四行程循环发动机也叫奥托循环发动机。发动机的四个活塞行程是进气、压缩、做功和排气。 进气冲程:在进气行程中，进气门打开，活塞向下移动，可燃混合气

通过进气门进入汽缸。适当浓度的可燃混合气是由燃料系统和化油器提供的。 压缩冲程:在活塞到达下止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。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甚至更少。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。 做功冲程: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。电火花点燃可燃混合气。可燃混合气开始发生剧烈燃烧，汽缸内压力达到3-5兆帕，甚至更高。作用于活塞上强大的推动力推动活塞向下运动，并将这一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。 排气冲程: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，将废气经排气门排出汽缸。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，新的可燃混合气被吸入汽缸。 汽缸活塞的四个冲程不断重复，推动着汽车前进。 The Power Mechanism of the Engine In a reciprocating engine, the power mechanism is called the crankshaft and connecting rod assembly. In this assembly, all of the major units such as the engine crankcase and cylinder block, the piston and connecting rod (see Figure 3.1), the crankshaft and flywheel work together to convert thermal energy into mechanical energy used to drive the vehicle. The engine crankcase and block are usually cast into one piece and therefore can be seemed as the largest and most intricate piece of metal in automobile. They are usually made of high-grade cast alloy iron to
improve wear characteristics of the cylinder. This major unit must be strong and rigid enough to withstand any bending or distortion. The piston converts the potential engines of the fuel into the kinetic energy that turns the crankshaft. The piston is a cylindrical shaped hollow part that moves up and down inside the engines cylinder. The piston is composed of piston head, piston rings, piston lands, piston skirt and piston pin hole. The piston head or "crown" is the top surface against which the explosive force is exerted. It may be flat, concave, and convex or any one of a great variety of shapes to promote turbulence or help control combustion. In some application, a narrow groove is cut into the piston above the top ring to serve as a heat dam to reduce the amount of heat reaching the top ring. The piston rings carried in the ring groove are of two basic types: compression rings and off-control ring. The upper ring or rings are to prevent compression leakage; the lower ring or rings control the amount of oil being deposited on the cylinder wall. The lower groove or grooves often have holes or slots in the bottom of the grooves to permits oil drainage from behind the rings. The piston lands are parts of piston between the ring grooves. The lands provide a seating surface for the sides of piston rings. The main section of a piston is known as the skirts. It forms a bearing area in contact with the cylinder wall. The piston pinhole in the piston also serves as a bearing for the piston pin, which is used to connect the connecting rod. In addition, because pistons operate under exceedingly difficult mechanical and thermal conditions, piston must be strong enough to stand the force of the expansion, yet light enough to avoid excessive inertia forces when their direction of travel is reversed twice each revolution. Piston must be able to withstand the heat from the burning air-fuel mixture, plus the heat generated by friction. The connecting rod is attached to the crankshaft at one end (big end) and to the piston at the other end (small end). In operation, the connecting rod is subjected to both gas pressure and inertia loads, and therefore, it must be adequately strong and rigid and light in weight as well. So they are generally fabricated from high quality steel. The connecting rod is in form of a bar with ring shaped heads at its end. They are composed of connecting rod small end, connecting rod shank, connecting rod big end, connecting rod cap, and connecting rod bearing half shells. Shank of the connecting rod is provided with an I-cross section to give the rod maximum rigidity with the minimum of weight. The big end of the rod is split so that it can be connected to the crankshaft. To avoid misplacing the rod caps during assembly, the connecting rods and their mating caps are marked on one side with serial numbers, starting with the first rod from the radiator, to identify their location in the engine. Some connecting rods have an oil spurt hole in the yoke or at the cap-mating surface to provide cylinder wall lubrication. The small end of the connecting rod is attached to the piston by a piston pin. In some cases the small end of the rod is clamped to the pin or has a bushing in it to allow the pin and rod oscillation. In other designs the pin is bolted to the rod. Connecting rods are usually drilled to provide lubrication to
the piston pin and also to spray oil into the bottom of the piston for piston cooling on some designs. The crankshaft serves to change the reciprocating motion of the piston into rotary motion and handles the entire power output. The periodic gas and inertia forces taken by the crankshaft may cause it to suffer wear and bending and tensional strains. The crankshaft therefore must be adequately strong and wear-resistant. So the crankshaft is either forged from a high quality steel or cast in a high-strong iron. The crankshaft is actually made up of various parts such as main bearing journals, rod journal, crank arm bearing, counter-balanced weight and flywheel end. The crankshaft revolves in bearings located in the engine crankcase, but the number of bearings used usually depends on the number of cylinders in the engine and the design of the engine. Mechanically, a crankshaft without special balanced weight would have severe vibration when revolving. In order to reduce or eliminate such vibration, it must be provided with counter balanced weights that extend radially from the crankshaft centerline in the opposite direction of the crank arms. In that way, the forces acting on the crankshaft are balanced and vibration is reduced. The rod journals are bored hollow in order to reduce the crankshaft inertia. Drilled diagonally through the crank arms are oil holes to supply oil to the rod journals. The flywheel is a relatively heavy metal wheel, which is firmly attached to the crankshaft. Its function is to help the engine to run smoothly by absorbing some of the energy during the power stroke and releasing it during the other strokes. In the front face of the flywheel, there is
a shallow indentation used to determine the position of the piston in the first cylinder. When this indentation is aligned with a special hole provided in the bell housing, the piston is at top dead center (TDC) or indicates the start of fuel injection into the first cylinder. The flywheels of some engines also carry marks indicating the serial numbers of the cylinders where the compression occurs. The flywheel marks and indentation are used for setting the valve and ignition systems relative to prescribed positions of the crankshaft. In conclusion, the connecting rod and crankshaft