畢業(yè)設(shè)計論文外文文獻翻譯中英文對照發(fā)動機基本原理

1、engine fundamentals automobiles have been operated successfully by electric motors ,steam engines ,and internal combustion engines .the internal combustion engine burns fuel within its cylinders and converts the expanding force of the burning fuel ,or combustion, into a rotary force used to propel t

2、he vehicle.there are several types of internal combustion engines: two-and four-cycle reciprocating piston engines ,gas turbine engines .however ,four-cycle reciprocating engines have been refined to such a degree that they have almost complete dominance of the automotive field .engines of other typ

3、es are described in chapter 18 ,diesel and other engines.many things are demanded of an engine used to propel an automobile. some of the requirements are:（1）ease of starting.（2）reliability.（3）power.（4）responsiveness.（5）economy in fuel ,oil ,and ,repairs.（6）ease of handling.（7）quiet operation.some of

4、 these factors conflict .for example ,a great amount of power can be had from an engine of sufficient size, but a super-size engines is not economical to operate .therefore ,all automobile engines are a compromise in order to obtain the desirable combination of performance and economy.engine fuels i

5、nternal combustion engines can be made to operate on almost anything that can be converted into a combustible gas, such as wood ,coal, alcohol, vegetable oils, mineral oils, etc. however, because of convenience, a variety of petroleum products are commonly used as fuel :gasoline, kerosene ,fuel oil

6、,liquefied petroleum gas (lp-gas) ect. what kerosene ,fuel oil ,or lp-gas is used it is necessary to alter the design of the engine to achieve efficient operation.engine deigngasoline engines used in automotive vehicles are of two basic types :four-cycle engines and two-cycle engines .either type ma

7、y be water-cooled ,or air-cooled .four- ,six-, and eight-cylinder engines are common however, three-, five-, ten- ,and twelve-cylinder engine are available.almost all automobile engines have more than one cylinder. these cylinders can be arranged in an inline ,opposed ,or v-type configuration. engin

8、es for other purpose ,such as aviation, are arranged as radial, inverted inline ,inverted v, and x-shaped configurations.reciprocating enginesin the typical automobile engine, a piston reciprocates (moves back and forth) within each cylinder. each piston is connected to the crankshaft by means of a

9、link known as a connecting rod.other types of reciprocating engines substitutes an eccentric, an inclined plate ,or a cam mechanism for the crankshaft .the piston engine has no crankshaft or connecting rods.engine componentsthe typical automotive engine is made up of several essential components. th

10、ese components are designed to provide efficient and reliable engine operation .the basic components in a four-cycle automotive engine include the following:（1）cylinder block.（2）crankshaft.（3）pitons.（4）piston rings.（5）connecting rods.（6）piston pin.（7）cylinder head.（8）valve train(includes valves and

11、valve operating mechanism). engine constructioncylinder block the cylinder block is cast in one piece. usually, this is the largest and the most complicated single piece of metal in the automobile.the cylinder block is a complicated casting made of gray iron (cast iron ) or aluminum. it contains the

12、 cylinders and the water jackets that surround them. to make the cylinder block, a sand form called a mold is made. then molten metal is poured into the mold. when the metal has cooled the sand mold is broken up and removed. this leaves the tough cylinder-block casting. the casting. the casting is t

13、hen cleaned and machined to make the finished block. cylinder blocks for diesel engines are very similar to those for spark-ignition engines. the basic difference is that the diesel-engine cylinder block is heavier and stronger. this is because of the higher pressures developed in the diesel-engine

14、cylinders.several engines have aluminum cylinder blocks. aluminum is relatively light metal, weighing much less than cast iron. also ,aluminum conducts heat more rapidly than cast soft to use as cylinder wall material. it wears too rapidly. therefore, aluminum cylinder blocks must have cast-iron cyl

15、inder liners or be cast from an aluminum alloy that has silicon particles in it. some manufactures make an aluminum cylinder block that does not have cylinder liners, or sleeves. instead ,the aluminum is loaded with silicon particles. silicon is a very hard material. after the cylinder block is cast

16、, the cylinders are honed. then they are treated with a chemical that etches eats away, the surface aluminum. this leaves only the silicon particles exposed. the pist. the cylinder block is cast in one piece. usually, this is the largest and the most complicated single piece of metal in the automobi

17、le.the cylinder block is a complicated casting made of gray iron (cast iron ) or aluminum. it contains the cylinders and the water jackets that surround them. to make the cylinder block, a sand form called a mold is made. then molten metal is poured into the mold. when the metal has cooled the sand

18、mold is broken up and removed. this leaves the tough cylinder-block casting. the casting. the casting is then cleaned and machined to make the finished block. cylinder blocks for diesel engines are very similar to those for spark-ignition engines. the basic difference is that the diesel-engine cylin

19、der block is heavier and stronger. this is because of the higher pressures developed in the diesel-engine cylinders.several engines have aluminum cylinder blocks. aluminum is relatively light metal, weighing much less than cast iron. also ,aluminum conducts heat more rapidly than cast soft to use as

20、 cylinder wall material. it wears too rapidly. therefore, aluminum cylinder blocks must have cast-iron cylinder liners or be cast from an aluminum alloy that has silicon particles in it. some manufactures make an aluminum cylinder block that does not have cylinder liners, or sleeves. instead ,the al

21、uminum is loaded with silicon particles. silicon is a very hard material. after the cylinder block is cast, the cylinders are honed. then they are treated with a chemical that etches eats away, the surface aluminum. this leaves only the silicon particles exposed. the piston and rings slide on the si

22、licon with minimum wear. piston the piston converts the potential energy 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. it has grooves around its perimeter near the top where the ring a

23、re placed. the piston fits snugly in the cylinder. it has grooves around its perimeter near the top where the rings are placed. the piston fits snugly in the cylinder. the pistons ate used to ensure a snug “air tight” fit.the piston in your engines cylinder are similar to your legs when you ride a b

24、icycle. think of your legs as pistons; they go up and down on the pedals, providing power. pedals are like the connecting rods; they are “attached” to your legs. the pedals are attached to the bicycle crank which is like the crank shaft, because it turns the wheels. to reverse this, the pistons (leg

25、s) are attached to the connecting rods ( pedals ) which are attached to the crankshaft (the bicycle rank). the power from the combustion in the cylinders powers the from the combustion rods to turn the crankshaft.connecting rod：the connecting rod shown in is made of forged high strength steel. it tr

26、ansmits force and motion from the piston to the crank pin on the crankshaft. a steel piston pin, or “wrist pin”, connects the small end of the connecting rod. some rods have a lock bolt in the small end. as the piston moves up and down in the cylinder, the pin rocks back and forth in the hole, or bo

27、re, in the piston. the big end of the connecting rod is attached to a crank pin by a rod bearing cap.connecting rod and rod-bearing caps are assembled during manufacture. then the hold for the bearing is bored with the cap in place. this is called line-bring. it make each rod and its cap a matched s

28、et. usually, the same number is stamped on the rod and cap. this prevents the caps setting mixed during engine service. if the caps are mixed, the bearing bore will not be round. an engine assembled with the rod bearing caps switched will probably lock the crankshaft. if the crankshaft turns, the be

29、aring will probably have improper clearance and early bearing failure will result.another reason for keeping the cap and rod matched is to prevent engine unbalance and unwanted vibration. all connecting rods in an engine must be as light as possible. but they must all weigh the same. if one rod is h

30、eavier than the other, the engine will vibrate. this could damage the engine.crankshaftthe crankshaft then main rotating member, or shaft , in the engine. it has crank-pins, to which the connecting rod from the pistons are attached . during the power strokes, the connecting rods force the crank-pins

31、 and therefore the crankshaft to rotate. the reciprocating motion of the pistons is changed to rotary motion as the crankshaft spins. this rotary motion is transmitted through the power train to the car wheels.the crankshaft is a strong, one-piece casting, or forging, or heat-treated alloy steel. it

32、 must be strong to take the downward force of power strokes without excessive bending. it must be balanced so the engine will run without excessive vibration. engine operating principlesmost automobile engines are internal combustion, reciprocating 4-stroke gasoline engines, but other types have bee

33、n used, including the diesel the rotary (wankel), the 2-stroke and the stratified charge.reciprocating means “up and down” or “back and forth”. it is the up and down action of a piston in the cylinder that produces power in a reciprocating engine. almost all engines of this type are built upon a cyl

34、inders block, or engine block. the block is an iron or aluminum casting that contains engine cylinders and passages called water jackets for coolant circulation. the top of the block is covered with the cylinder head, which forms the combustion chamber. the bottom of the block is covered with an oil

35、 pan or oil sump.power is produced by the linear motion of a piston in a cylinder. however, this linear motion must be changed into rotary motion to turn the wheels of cars and trucks. the piston is attached to the top of a connecting rod by a pin, called a piston pin or wrist pin. the bottom of the

36、 connecting rod is attached to the crankshaft. the connecting rod transmits the up-and-down motion of the piston to the crankshaft, which changes it into rotary motion. the connecting rod is mounted on the crankshaft with large bearings called rod bearings. similar bearings, called main bearings, ar

37、e used to mount the crankshaft in the block.the diameter of the cylinder is called the engine bore. displacement and compression ratio are two frequently used engine specifications. displacement indicates engine size, and compression ratio compares the total cylinder volume to compression chamber vo

38、lume.the term “stroke” is used to describe the movement of the piston within the cylinder, as well as the distance of piston travel. depending on the type of engine the operating cycle may require either two or four strokes to complete. the 4 stroke engine is also called otto, who first applied the

39、principle in 1876. in the 4 stroke engine, four strokes of the piston in the cylinder are required to complete one full operating cycle. each stroke is named after the action it performs intake, compression, power, and exhaust in that order.（1）intake strokeas the piston moves down, the vaporized mix

40、ture of fuel and air enters the cylinder through the open intake valve. to obtain the maximum filling of the cylinder the intake valve opens about 10°before t. d. c., giving 20°overlap. the inlet valve remains open until some 50°after b. d . c. to take advantage of incoming mixture.（2

41、）compression strokethe piston turns up, the intake valve closes, the mixture is compressed within the combustion chamber, while the pressure rise to about 1mpa depending on various factors including the compression ratio, throttle opening and engine speed. near the top of the stroke the mixture is i

42、gnited by a spark which bridges the gap of the spark plug.（3）power stroke the expanding gases of combustion produces a rise in pressure of the gas to some 3.5 mpa, and the piston is forced down in the cylinder. the exhaust valve opens near the bottom of the stroke.（4）exhaust stroke the piston moves

43、back up with the exhaust valve open some 50°before b. d. c. , allowing the pressure within the cylinder to fall and to reduce back piston during the exhaust stroke, and burned gases are pushed out to prepare for the next intake stroke. the intake valve usually opens just before the exhaust stro

44、ke.this 4 stroke cycle is continuously repeated in every cylinder as long as the engine remains running.a 2 stroke engine also goes through four actions to complete one operating cycle. however, the intake and the compression actions are combined in one stroke, and the power and exhaust actions are

45、combined in the other stroke. the term 2 stroke cycle or 2 stroke is preferred to the term 2 cycle, which is really not accurate.in automobile engines, all pistons are attached to a single crankshaft. the more cylinders an engine has he more power stroke produced for each revolution. this means that

46、 an 8-cylinder engine runs more smoothly because the power strokes are closer together in time and in degrees of engine rotation.the cylinders of multi cylinder automotive engines are arranged in one of three ways. (1) inline engines use a single block of cylinder. most 4 cylinder and any 6 cylinder

47、 engines are of this design. the cylinders do not have to be vertical. they can be inclined to either side.(2) v-type engines use two equal banks of cylinders, usually inclined 60 degrees or 90 degrees from the each other. most v-type engines have 6 or 8 cylinders, although v 4 and v 12 engines have

48、 been built.(3) horizontally opposed or pancake engines have two equal banks of cylinders 180degrees apart. these space saving engine designs are often air cooled, and are found in the chevrolet carver, porsches, subaru s, and volkswagens. subarus design is liquid cooled. late-model volkswagen vans

49、use a liquid cooled version of the air cooled vw horizontally opposed engine. 發(fā)動機基本原理汽車已經(jīng)工作的非常成功通過電子馬達，蒸汽機，和內(nèi)燃機，內(nèi)燃機在氣缸里燃燒并且將燃料燃燒發(fā)出的膨脹力轉(zhuǎn)換或旋轉(zhuǎn)力用來推動汽車。內(nèi)燃機有好幾種類型：兩沖程或四沖程的活塞發(fā)動機，渦輪發(fā)動機，自由活塞的發(fā)動機。然而，四沖程的發(fā)動機改進的程度如此之高。已經(jīng)幾乎統(tǒng)治壟斷了汽車的領(lǐng)域，其它類型的發(fā)動機，如柴油機在以后再敘述。發(fā)動機上的許多東西都是有要求，它們常用于推動發(fā)動機，許多的要求如下：（1）容易起動性能：(2)可靠性。(3)動力性。(

50、4)靈敏性。(5)燃料，機油，維修的經(jīng)濟性。(6)輕便的操縱性。(7)安全的工作性能。有些性能是互相沖突的，例如，很大的動力需要以尺寸是足夠大的發(fā)動機上獲得，但是這么大的尺寸的發(fā)動機工作時經(jīng)濟性不好，因此，所有汽車的發(fā)動機都是為獲的滿意的性能和經(jīng)濟性。發(fā)動機的燃料內(nèi)燃機能被制造或依靠幾乎任務(wù)東西運行的，只要這些東西能轉(zhuǎn)換或燃料的氣體。例如木材，煤礦，酒精，植物油，礦物油等，燃而，因為適合方便，各種各樣的石油產(chǎn)品被用來作為燃料，汽油，煤油，液化氣等當煤油，燃油或液化氣被使用時，必須改變發(fā)動機的設(shè)計從而獲得較高的效率。發(fā)動機的設(shè)計用于車輛上的汽油發(fā)動機有兩種基本類型，四沖程發(fā)動機任何其中一種類型都

51、應(yīng)是水冷或風冷，四缸六缸和八缸的發(fā)動機都是普通常見的燃而三缸五缸十缸的發(fā)動機都是可以利用的幾乎所有汽車的發(fā)動機的汽缸都不少于一個。這些汽缸都被設(shè)計或線性排列對置或v型的結(jié)構(gòu)，其它途徑的發(fā)動機例如航空應(yīng)用的都被設(shè)計成輻射狀的倒置反轉(zhuǎn)的v型的結(jié)構(gòu)。往復(fù)式發(fā)動機在這種類型汽車的發(fā)動機里，活塞在各自的汽缸里往復(fù)運動。每個活塞通過連桿被連接在曲軸上。其它類型往復(fù)式發(fā)動機的的代表是離心的，有斜向的盤子，或在曲軸上有一個凸輪機構(gòu)。自由活塞的發(fā)動機沒有曲軸或連桿。發(fā)動機的部件典型的汽車的發(fā)動機是由許多必須的部件組成的，這些部件被設(shè)計成用來提供發(fā)動機運行的可靠性和高效率性。四缸汽車發(fā)動機的基本部件包括：（1）汽

52、缸體。（2）曲軸。（3）活塞。（4）活塞環(huán)。（5）連桿。（6）活塞銷。（7）汽缸蓋。（8）氣閥結(jié)構(gòu)。 發(fā)動機結(jié)構(gòu)汽缸體汽缸體是鑄造成而成一體的。通常，這是發(fā)動機上最大，最復(fù)雜的鐵制的部件。汽缸體是用灰鑄鐵或鋁鑄造成的。它包括汽缸體本身和環(huán)繞在周圍的水套。要做汽缸體需要一個沙模模型，然后將金屬溶液倒入模型中。當金屬溶液冷卻后，將模型打破拿走，只剩下了一個粗糙的汽缸體。然后將它清潔機加工，最后完成一個汽缸體。柴油機用的發(fā)動機與汽油機用的非常相似。最根本的不同是柴油機的比汽油機的更加堅固更沉。這是因為柴油機產(chǎn)生的氣缸壓力更大。有許多發(fā)動機用的是鋁制的氣缸。鋁也是一種金屬，重量比鑄鐵要輕很多，并且鋁的

53、導(dǎo)熱速度比鑄鐵的要快。這就是說它發(fā)生爆燃的可能性要小。然而，鋁作為汽缸體材料來說較軟，鋁的磨損也非?？?。因此，鋁制氣缸要有氣缸襯套，因此在鋁中加入硅粒子形成鋁合金。一些制造商制造的鋁制氣缸也沒有氣缸。他在鋁中加入了硅粒子。硅是非常硬的材料。氣缸在鑄造后，要進行研磨。然后給它們涂上一層化學制劑，把表面上的鋁腐蝕掉。這樣只剩下硅存在表面。此時，活塞和環(huán)磨損最小?；钊钊麑⒒瘜W能轉(zhuǎn)變?yōu)閯幽軅鹘o曲軸?；钊且粋€圓柱狀放在氣缸內(nèi)的物體?；钊敳坑蟹胖没钊h(huán)的活塞環(huán)槽?；钊梢愿线m的放在氣缸中?；钊h(huán)用來保持氣缸的氣密性?；钊跉飧字芯拖衲阍隍T自行車時的腿。認為你的腿和活塞一樣；當上下踏腳踏板時可以產(chǎn)生動力。腳踏板就像連桿；它連著你的腿。踏板連著自行車的軸，這個軸類似于曲軸因為它也用來驅(qū)動車輪。反過來，