汽車自動變速器構(gòu)造與檢修,單擊此處編輯母版文本樣式,第二級,第三級,第四級,第五級,*,*,Project 5 Starting System and Ignition System,1,2,Project 5 Starting System and Ignition System,掌握汽車啟動系統(tǒng)、點火系統(tǒng),的組成結(jié)構(gòu)和工作過程,掌握系統(tǒng)主要部件的的專業(yè)術(shù),語表達(dá),知識目標(biāo),能讀懂發(fā)動機(jī)啟動系統(tǒng)、點火,系統(tǒng)的課文材料,能熟記啟動馬達(dá)、點火線圈、,點火器、一級和二級繞組等關(guān)鍵,零部件及其組成的相關(guān)專業(yè)詞,匯、術(shù)語,能看圖寫出零件名稱,;,能力目標(biāo),3,Task 1 Starting-motor system,1.New words and expressions,initiate iniieit vt.,開始、讓,加入,minimum minimm n.,最低限度、最小量,adj.,最低的、最小的,atomize tmaiz v.,使分裂為原子、將,噴成霧狀,cyclic saklk,sklk adj.,周期的、循環(huán)的、輪轉(zhuǎn)的,adequate dikwit adj.,充分的、足夠的、適當(dāng)?shù)?momentum mumentm n.,動力、沖力,exert iz:t vt.,用,(,力,),、盡,(,力,),、施加,breakaway brek,we n.,脫離、擺脫,standstill stnd,stl n.,靜止?fàn)顟B(tài)、停頓,peak pi:k n.,尖端、最高點、高峰,compensate kmpenseit vt.&vi.,補償、報酬,prerequisite pri:rekwzt n.,先決條件、前提,知 識,準(zhǔn) 備,4,1.New words and expressions,minimal miniml adj.,正式,最小的、極少的,ejection i,dekn n.,噴出,排出物,helical helikl adj.,螺旋狀的,spline splain n.,齒條、止轉(zhuǎn)楔、花鍵,vt.,用花鍵聯(lián)接、開鍵槽,axially adv.,軸向方向,charge trd n.,電荷，,vt.,使充電,generator dn,ret n.,發(fā)電機(jī),dead weight n.,靜負(fù)載,;,固定負(fù)載,relay switch,繼電器開關(guān),lead-acid battery,鉛酸蓄電池,知 識,準(zhǔn) 備,5,Starting-motor system,任務(wù),實施,The starting system,turns the crankshaft of the internal combustion engine at first.After that,the engine can use the power of the burning air fuel mixture to run by itself.It mainly consists of a starter motor and the control circuit(shown in figure 5.1.1).A starter motor converts electrical energy stored in the battery into a mechanical force(torque)to start the internal combustion engine.The system must be capable of supplying sufficient power to rotate the engine at the minimum speed required to successfully initiate the combustion process in the engine cylinders.In modern vehicles this is approximately 100 rpm.,The internal combustion engine,is not self-starting and this minimum speed is required to allow the engine to form a reasonably well-atomized fuel mixture in the cylinder and compress it sufficiently for combustion to take place.In addition the starting motor must be able to operate with the very high cyclic torque demand required when rotating an internal combustion engine at cranking speed.The speed must be adequate to allow the momentum of the moving parts to carry the engine over from one firing stroke to another.,6,The starting-motor system,任務(wù),實施,7,Starting-motor system,任務(wù),實施,A starter-motor pinion driving an engine flywheel must exert sufficient torque to provide breakaway from the static condition,i.e.it must rotate the engine from standstill and accelerate up to cranking speed.Interestingly the main consideration that affects the torque required to start the engine(apart from its type-spark or compression ignition)is not the total displacement of the engine but the displacement of the individual cylinders.This dictates the peak torque which must be overcome to generate the compression pressures in the cylinders,i.e.larger cylinders require larger starter motors,not necessarily larger engines.,The starting process,All vehicle electric starter motors operate in a similar sequence as follows(see the figure 5.1.2):,1.Drive engagement:when the driver requests an engine start,the starting motor has to first establish a mechanical link between itself and the engine.The starter motor is mounted somewhere on the engine block,normally via a flange-type mounting,and drives a gear wheel mounted on the engine flywheel at the back of the engine.,8,Starting-motor system,任務(wù),實施,On requesting,a start,the starter motor drive pinion must move into position and engage with the flywheel teeth.If tooth-to-tooth blocking occurs,then the engagement system must compensate for this and turn the pinion so that the teeth misalign and then engage correctly,thus being positioned properly for torque transmission.This status is a prerequisite before the motor can be supplied with full battery current to start the engine.,2.Torque transmission,:once the drive pinion is fully engaged into the flywheel ring gear teeth,transmission of torque to rotate the engine can begin.At this point,the motor can be switched on with full power.This is normally effected via a solenoid switch which is appropriately rated to handle the large current with minimal electrical resistance.The motor begins to rotate and,due to the transmission ratio between the starter and engine,a large amount of torque is applied to the crankshaft to overcome the static friction and rotate the engine.The compression and expansion in the engine cylinders means that the torque required varies considerably during the process.,9,Starting-motor system,任務(wù),實施,3.Engine start-up:a warm,modern,fuel-injected engine will normally start within two revolutions.When cold,the engine needs longer.As soon as fuel is injected/ignited the engine will generate its own torque and therefore increase the rotation speed of the engine.After a short time the engine accelerates the starter and at this point,even if the motor is still powered,the torque must not be transmitted back from the engine as this will over-speed the starter motor and cause permanen。