发动机专业英语(柴油机和汽油机)

INTERNAL COMBUSTION ENGINE （内燃机） 1 principle of operation （工作原理 or 操作原理） 1.1 Engine and power（发动机和功率） Engine is used to produce power. The chemical energy in fuel 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 engine. 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 the 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. 1.2 Engine Terms （发动机术语） 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 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: TDC(Top Dead Center): the position of the crank and piston when the piston is farther away from the crankshaft. BDC(Bottom Dead Center): the position of the crank and piston when the piston is nearest to the crankshaft. Stroke: the distance between BDC and TDC; stroke is controlled by the crankshaft. Bore: the internal diameter of the cylinder. Swept volume: the volume between TDC and BDC. Engine capacity: this is the swept volume of all the cylinders, e.g. a four-stroke having a capacity of two liters(2000cm) has a cylinder swept volume of 50cm. Clearance volume: the volume of the space above the piston when it is at TDC. Compression ratio = (swept vol + clearance vol)/(clearance vol) Two-stroke: a power stroke every revolution of the crank. Four-stroke: a power stroke every other revolution of the crank.. 1.3 The Four-stroke Spark-ignition Engine Cycle（四冲程火花塞点火发动机循环） The spark-ignition engine is an internal-combustion engine with externally supplied in ignition, which converts the energy contained in the fuel to kineticenergy.(动能) The cycle of operations is spread over four piston strokes. To complete the full cycle it takes two revolutions of the crankshaft. The operating strokes are: Intake stroke 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 opened by moving the inlet valve. The exhaust valve remains tightly closed. Compression stroke As the piston moves upward to compress the fuel mixture trapped in the cylinder, the valves are closed tightly. This compression action heats the air/fuel mixture slightly and confines it within a small area called the combustion chamber. Power stroke Just before the piston reaches the top of its compression stroke, an electrical spark is introduced from a spark plug screwed into the 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 stroke turns the crankshaft with great force. Exhaust stroke Just before the bottom of the power stroke, the exhaust valve opens. This allows the piston, as it moves upward, to push the hot, 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 immediately. 1.4 Engine Overall Mechanics（发动机总体机构） The engine has hundreds of other parts. The major parts of engine are engine block, engine heads, pistons, connecting rods, crankshaft and valves. 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. New Words Piston 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 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 compression ratio 压缩比 revolution 旋转,转数 every other 每隔一个 spread over 分布,遍及 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 Engine Block and Cylinder Head（发动机机体和气缸盖） 2.1 Engine Block（发动机机体） The engine block is the basic frame of the engine. All other 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 block is made of gray iron, or an alloy (mixture) of gray iron and other metals, such as nickel or chromium. Engine blocks are castings. Some engine blocks, especially those 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 aluminum. 2.2 Cylinder Head（气缸盖） 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 cylinder head types are the hemi, wedge, and semi-hemi. All three of these terms refer to the shape of the engine's 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 camshaft 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. 2.3 Gasket（垫圈） 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 cylinder head gasket. This is a sandwich gasket, i.e. a sheet of asbestos （[ æs'bestəs ]石棉）between two sheets of copper, both these materials being able to withstand the high temperature and pressures within the engine. 2.4 Oil Pan or Sump（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 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. New Words engine block 缸体 cylinder 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 1. What do TDC, BDC, stroke, compression ratio and engine capacity stand for? 2. How do you calculate swept volume and compression ratio? 3. What controls the length of the stroke? 4. List the main parts of the engine overall mechanics? 5. What are the main function of the engine block? 3 Piston Connecting Rod and Crankshaft（活塞连杆和曲轴） 3.1 Piston Assembly （活塞总称） The piston is an important part of a four-stroke cycle engine. Most 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. These 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. The piston itself, its rings and the piston pin are together called the piston assembly. 3.2 Piston（活塞） To withstand the heat of the combustion chamber, 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 the piston is the head, or crown. The thin part is the skirt The sections between the ring grooves are called ring lands. The piston crown may be flat, concave,dome or recessed. 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. 3.3 Piston Rings（活塞环） As Fig.1-9 shows, piston 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. In modern engines, each piston has three rings. (Piston in older engines sometimes had four rings, or even five.) The ring’s 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 compression 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. During 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 the 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. 3.4 Piston Pin （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 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-strengh steel and have a hollow center. Many pins are chrome-plated to help them wear better. 3.5 Connecting rod （连杆） The connecting rod is made of forged high-strength steel. 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 the 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 forged alloy steel. 3.6 Crankshaft（曲轴） The crankshaft, in conjunction with the connecting rod, coverts the reciprocating motion of the piston to the rotary motion needed to drive the vehicle. It is usually made from carbon steel which is alloyed with a small proportion of nickel.The main bearing journals fit into the cylinder block and the big end journals align with the connecting rods. At the rear end of the crankshaft is attached the flywheel, and at the front end are the driving whells for the timing gears, fan, cooling water and alternator. The throw of the crankshaft, the distance between the main journal and the big end centers, controls the length of the stroke. The stroke is double the throw, and the stroke-length is the distance that the piston travels from TDC to BDC and vice versa. 3.7 Flywheel （飞轮） The flywheel is the made from carbon steel. It fit s onto the rear of the crankshaft. As well as keeping the engine rotating between power strokes it also carries the clutch, which transmits the drive to the transmission, and has the starter ring gear around its circumference. There is only one working stroke in four so a flywheel is needed to drive the crankshaft during the time that the engine is performing the non-power strokes. New Words Comprise 由。。。。。。。组成，包含 Inter 惯性，惯量 Radius 半径，范围 Circular 圆形的 Steel band 钢圈 Fit into 放入，放进 Groove 凹槽 Piston pin 活塞销 Pin boss 活塞销凸台 Withstand 抵抗 Hollow 空的 Brunt 冲力 Crown 活塞顶 Skirt 裙部 Ring land 环带 Concave 凹的，凹入的 Dome 圆顶 Recessed 隐蔽的 Cylinder wall 气缸壁 Cylinder bore 缸筒 Splash 飞溅 chrome-face 表 关于同志近三年现实表现材料材料类招标技术评分表图表与交易pdf视力表打印pdf用图表说话 pdf 面镀银的 Untwist 朝相反方向的 In place 在适当位置 Chrome-plated 镀铬的 Forge 伪造，仿造 Crankpin 曲轴销 Bush 轴瓦，套筒 Bronze 青铜 Crankshaft journal 曲轴轴颈 Steel-backed 钢背的 Lead 铅 Tin 锡 Splint 切口，中断，分配，分离 In conjunction with 连同 Reciprocating motion 往复运动 Rotary 旋转的 Carbon steel 碳钢 Journal 轴颈 Align with 匹配 Overlap 重叠 Timing gear 正时齿轮 Throw 摆幅 Vice verse 反之亦然 Impulse 脉冲 Space out 隔开，分隔 Through out 遍及 Diagram 图表 Firing order 点火顺序 Companion 成对 Circumference 圆周 4 Valve System（气阀系统） The valve system is made up of those parts needed to open and close the valves at just the right time. 4.1 Valve Operation （气阀运动） To coordinate the four-stroke cycle, a group parts called the valve train opens and closes the valves ( moves them down and up, respectively ). These valve movements must take place at exactly the right moments. The opening of each valve is controlled by a camshaft. 4.1.1 Camshaft(OHC) Valve Train Overhead（凸轮轴气阀机构顶置） The cam is an egg-shaped piece of metal on a shaft that rotates in coordination with the crankshaft. The metal shaft, called the camshaft, typically has individual cams for each valve in the engine. As the camshaft rotates, the lobe, or high spot of the cam, pushes against parts connected to the stem of the valve. This action forces the valve to move downward. This action could open an inlet valve, or open an exhaust valve for an exhaust stroke. As the camshaft continues to rotate, the high spot moves away from the valve mechanism. As this occurs, valve spring pull the valve tightly closed against its opening, called the valve seat. Valve in modern car engines are located in the cylinder head at the top the engine. This is known as an overhead valve (OHC) configuration. In addition, when the camshaft is located over the cylinder head, the arrangement is known as overhead camshaft (OHC) design. Some high-performance engine have two separate camshafts, one for each set of inlet and exhaust valves. These engines are known as overhead-camshaft (DHOC) engine. 4.1.2 Push-rod Valve Train（推杆气阀机构） The camshaft also can be located in the lower part of the engine, within the engine block. To transfer the motion of the cam upward to the valve, additional parts are needs. In this arrangement, the cam lobs push against round metal cylinders called follower upward ( away from the camshaft ). The cam follower rides against a push rod, which pushes against a rocker arm. The rocker arm pivots on a shaft through its center. As one side of the rocker arm moves up, the other side moves down, just like a seesaw. The downward-moving side of the rocker arm pushes on the valve stem to open the valve. Because a push-rod valve train has additional parts, it is more difficult to run at high speeds. Push-rod engines typically run at slower speeds and, consequently, produce less horsepower than overhead-camshaft designs of equal size. ( Remember, power is the rate at which work is done.) 4.2 Valve Clearance （气门间隙） When the engine runs in compression stroke and power stroke, the valves must close tightly on their seats to produce a gas-tight seal and thus prevent the gases escaping from the combustion chamber. If the valves do not close fully the engine will not develop fill power. Also the valve heads will be liable to be brunt by the passing hot gases, and there is the likelihood of crown touching an open valve, which can seriously damage the engine. So that the valves can close fully some clearance is needed in the operating mechanism. This means that the operating mechanism must be able to move sufficiently far enough away from the valve t allow the valves to be fully closed against its seat by the valve spring. However, if the clearance is set too great this will cause a light metallic taping noise. 4.3 Valve Timing （气门正时） The time at which valves open and close ( valve timing ) and the duration of the valve opening in stated in degrees of crankshaft rotation. For example, the intake valve normally begins to open just before the piston has reached the top dead center. The valve remains open as the piston travels down to BDC and even past BDC. This is intake valve duration.An example of this could be stated as follows: IO at 17BTDC, IC at 51ABDC ( or, intake opens 17before top dead center, intake closes 51after bottom dead center ). Intake valve duration in this case is 248 of crankshaft rotation. This leaves 129 duration for the compression stroke since compression ends when the piston reaches TDC. At this point the power stroke begins. The power stroke ends when the exhaust valve begins to open approximately at 51 before bottom dead center. The duration of the power stroke in this case is also 129. Since the exhaust valve is opening at 51 BBDC, this begin