机械外文翻译文献翻译汽车发动机凸轮轴.docx
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机械外文翻译文献翻译汽车发动机凸轮轴.docx
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机械外文翻译文献翻译汽车发动机凸轮轴
机械外文翻译文献翻译汽车发动机凸轮轴
机械专业中英文文献翻译
Automotiveenginecamshaft
Briefintroduction
Thecamshaftisapartofthepistonengine.Itsroleistocontroltheopeningandclosingoperationofthevalve.Althoughthecamshaftrotationalspeedinafour-strokeengineisahalfofthecrankshaft(thesameasthecamshaftrotationalspeedinatwo-strokeenginewiththecrankshaft),butusuallyitisstillveryhighspeed,butalsoneedtowithstandthelargetorque,sothedesignrightdemandingcamshaftintermsofstrengthandsupportmaterialisgenerallyaspecialcastiron,occasionallyusingforgings.Valvemotionlawrelatedtoenginepowerandoperationcharacteristics,thedesigninthedesignprocessoftheenginecamshaftoccupiesaveryimportantposition.
Structure
Themainbodyofthecamshaftisthesameastheonewiththecylinderlengthofthecylindricalrod.Theabovesetshaveseveralcamfordrivingthevalve.Oneendofthecamshaftcamshaftbearingsupportandtheotherendisconnectedtothedrivewheels.
Camsidewasegg-shaped.Thedesignaimstoensurethethecylindersufficientairintakeandexhaust,specifically,withintheshortestpossibletimetocompletethevalveopeningandclosingmovements.Inaddition,takingintoaccountthedurabilityoftheengineandthesmoothnessofoperation,thevalvecannotbegeneratedduetothedecelerationprocessofopeningandclosingmovementstoomuchtoolargetheimpactofseriouswearandtearofthevalve,otherwiseitwillcauseanincreaseinnoiseorotherseriousconsequences.Therefore,thecamandthepoweroftheenginetorqueoutputaswellastheoperationoftheridethereisadirectrelationship.
Generallyinlineengine,acamcorrespondingtoavalveV-typeengineorhorizontalopposedtypeengine,everytwovalvesshareacam.Therotaryenginethevalvelesswithgasenginebecauseofitsspecialstructure,doesnotneedtocam
Position
Inthelongperiodoftime,thebottom-mountedcamshaftinaninternalcombustionengineismostcommon.Typicallysuchengines,thevalveislocatedinthetopoftheenginecamshaftmachine,i.e.,so-calledtheOHV(OverHeadValve,OHV)engines.Usuallycamshaftlocatedonthesideofthecrankcase,throughthegasdistributionagencies(suchastappet,pushrod,rocker,etc.)valvecontrol.Bottom-mountedcamshaftgeneralalsocalledside-mountedcamshaft.Fardistancevalve,andeachcylinderisusuallyonlytwovalvesinsuchanenginecamshaft,sothespeedisusuallyslower,ridecomfortispoor,theoutputpowerisalsorelativelylow.However,theengineoutputtorqueandlow-speedperformanceofthisstructureisrelativelygood,relativelysimplestructureandeasymaintenance.
Nowmostoftheproductioncar'sengineisequippedwithoverheadcamshaft.Theoverheadcamshaftsstructureclosertothecamshaftvalve,toreducethekineticenergyofthewastecaused
机械专业中英文文献翻译
bythebottom-mountedcamshaftduetothelargerdistancebetweenthecamshaftandthevalveshuttle.Overheadcamshaftoftheenginevalveopeningandclosingactionisrelativelyrapid,andhencehigherspeed,andthesmoothrunningisalsobetter.TheengineofthetheoverheadcamshaftsstructureappearedearliertheSOHC(SingleOverHeadCam,overheadsinglecamshaft)engine.Thisengineisonlyinstalledatthetopofacamshaft,andthereforegenerallyonlytwotothreevalvesofeachcylinder(theintakeairatotwoexhaust),thehigh-speedperformancehasbeenlimited.TechnologyupdatesDOHC(DoubleOverHeadCam,doubleoverheadcamshaft)engine,thisenginewithatwocamshaftspercylindercanbeinstalledfourtofivevalves(intaketwotothree,Paigastwo),high-speedperformancesignificantlyimproved,butatthesametimethelow-speedperformancewillbeaffectedtosomedegree,thestructurewillbecomplicatedanddifficulttorepair.
Classification
Accordingtothethecamshaftnumberofhowmany,canbedividedintosingleoverheadcamshaft(SOHC)anddoubleoverheadcamshaft(DOHC),twokinds.Thesingleoverheadcamshaftcamshaftisonlyonecamshaft,doubleoverheadcamshaftistwo,thisistoostraightforwardexplanation.
Thesingleoverheadcamshaftwithacamshaftinthecylinderhead,directdriveintotheexhaustvalve,ithasasimplestructure,suitableforhigh-speedengine.Generallyusedinthepastsidecamshaft,thecamshaftinthecylinderside,isdrivendirectlybyatiminggear.Thevalveliftertotherotationofthecamshaftisconvertedintoreciprocatingmotionofthevalvemustbeusedtotransferpower.Thus,morepartsofthereciprocatingmotion,theinertialmass,isnotconducivetohigh-speedmovementoftheengine.Moreover,theslendertappethasacertaindegreeofflexibility,pronetovibration,acceleratedcomponentwear,eventhevalvecontrolislost.
DOHCcylinderheadequippedwithtwocamshafts,oneisusedtodrivetheintakevalve,theotherfordrivingtheexhaustvalve.Doubleoverheadcamshaftcamshaftandvalvespringdesignlessdemanding,especiallyforthehemisphericalcombustionchamberofthevalveV-shapedconfiguration,butalsofacilitateandusedinconjunctionwithfour-valvegasdistributionagencies.Fault
Camshaftcommonfaultsincludingabnormalwearandtear,abnormalwearofthesymptomsoftenfirstappearbeforetheoccurrenceofabnormalsoundaswellasfracture,abnormalsoundandfracture.
(1)Camshaftalmostattheendoftheenginelubricationsystem,lubricationsituationisnotoptimistic.IftheoilpumpistoolongandsoinsufficientoilpressureorthelubricantsRoadblockagecausedbylubricatingoilcannotreachthecamshaftbearingcapfasteningboltstighteningtorquecausedbyexcessiveoilcannotenterthethecamshaftgapwillcausingabnormalwearofthecamshaft.
(2)theabnormalwearofthecamshaftcausesthegapincreasesbetweenthecamshaftbearing,thecamshaftmovementoccurswhentheaxialdisplacement,resultinginabnormalnoise.Abnormalwearwillleadtoincreasedgapbetweenthedrivecamwithhydraulictappets,cam
机械专业中英文文献翻译
combinedwithhydraulictappetswillcollide,resultinginabnormalnoise.
(3)camshaftsometimesfractureandotherseriousfault,commoncausesofhydraulictappetcrackedorseverelyworn,seriouspoorlubricationthecamshaftpoorqualityandcamshafttiminggearrupture.
(4)Insomecases,thefailureofthecamshaftisman-madecauses,inparticularthemaintenanceoftheenginecamshaftnotcorrectdisassembly.Suchasdemolitionofthecamshaftbearingcapswithahammerstrengthknockingorpryingwithascrewdriver,orinstallthebearingcapinstalledthewrongpositiondoesnotmatchtheresultinthebearingcapandbearing,orbearingcoverthefasteningbolttighteningtorqueistoolarge.Installbearingcapshouldpayattentiontothedirectionofthearrowandthepositionnumbermarkedonthesurfaceofthebearingcap,andinstrictaccordancewiththeprovisionsoftorqueusingthetorquewrenchtightenthebearingcapfasteningbolts.
Refit
Inordertoenhancethepoweroftheengine,someconvertedstoresamodifiedcamshaftenginefacelifthighanglecamshaft(Hi-camshaftCAM)isacommonformofmodifiedmethod.Thismodificationoperationisnotcomplicated,butbecauseofthelackofunderstandingofsomemodificationcamonthecamshaftangleandworkssothatthemodifiedeffectisnotobviousevenleadtothedeteriorationoftheperformanceoftheengine.
Highanglecamshaftrelativetoordinarycamshaftcamangleofabout240?
highangle
camshaftcamanglecanoftenreachover280?
.Thelargeangleofthecamshaftcanextendthe
valveopentime,increasethevalvelift,theintakevalveandtheexhaustvalveopenasearlyandlateoff,sothatmoreairintothecylinder,inordertoimprovetheengine,thepowerofthehighspeedoutput.Shouldchooseforcivilianvehicles,modifiedcamcamshaftangle278,willbeasignificantincreaseinworkingananglegreaterthan278?
camshaftvalveoverlapangle,sothat
thepoweroftheenginehighspeedimprovealot,butenginecylindersealisnotgoodatlowspeedandcausetheidlingseriousjitteroreventurnoff,sothatthevehiclecannotadapttoeverydayuse,andcanonlybeusedforcompetitionpurposes.
Productiontechnology
Thecamshaftisoneofthekeypartsoftheengine,thehardnessofthecamshaftpeachapicalandwhitelayerdepthistodeterminethekeytechnicalindicatorscamshaftlifeandengineefficiency.,Shouldbeconsideredtoensurethatthecamhasasufficientlyhighhardnessandafairlydeepwhitelayerpremisejournaldoesnotappearhighcarbide,sothatithasabettercuttingperformance.
Currently,themainmethodofdomesticandforeignproductioncamshaft:
steelforgingblankbycuttingthecampeachtipmartensiticlayerformedsomeofthehigh-frequencyquenchingprocess.Theendofthe1970s,GermanyandFrancehavedevelopedanewcamshaftargonarcremeltingprocess;hardenedcastironcamshaftotherwisedominatedbytheUnitedStates;chilledcastironcamshaftmainlytoJapanandFrance;wellcampartsoftheCr-Mn-Moalloycoatingscastingsurfacealloyingproduction.
机械专业中英文文献翻译
汽车发动机凸轮轴
简介
凸轮轴是活塞发动机里的一个部件。
它的作用是控制气门的开启和闭合动作。
虽然在四冲程发动机里凸轮轴的转速是曲轴的一半(在二冲程发动机中凸轮轴的转速与曲轴相同),不过通常它的转速依然很高,而且需要承受很大的扭矩,因此设计中对凸轮轴在强度和支撑方面的要求很高,其材质一般是特种铸铁,偶尔也有采用锻件的。
由于气门运动规律关系到一台发动机的动力和运转特性,因此凸轮轴设计在发动机的设计过程中占据着十分重要的地位。
构造
凸轮轴的主体是一根与汽缸组长度相同的圆柱形棒体。
上面套有若干个凸轮,用于驱动气门。
凸轮轴的一端是轴承支撑点,另一端与驱动轮相连接。
凸轮的侧面呈鸡蛋形。
其设计的目的在于保证汽缸充分的进气和排气,具体来说就是在尽可能短的时间内完成气门的开、闭动作。
另外考虑到发动机的耐久性和运转的平顺性,气门也不能因开闭动作中的加减速过程产生过多过大的冲击,否则就会造成气门的严重磨损、噪声增加或是其它严重后果。
因此,凸轮和发动机的功率、扭矩输出以及运转的平顺性有很直接的关系。
一般来说直列式发动机中,一个凸轮都对应一个气门,V型发动机或水平对置式发动机则是每两个气门共享一个凸轮。
而转子发动机和无阀配气发动机由于其特殊的结构,并不需要凸轮。
位置
在以前很长的一段时间里,底置式凸轮轴在内燃机中最为常见。
通常这样的发动机
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