汽车实用英语.doc

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1、P82UnitEighttextEngineIgnitionSystemAllgasolineenginesrequiresomeformofignitionsystem．Thepurposeofthissystemisto。supplytothesparkplugs，withintheenginecombustionchambers，high．voltagesurges．Furthermore，theignitionsystemmustprovidethesesurgesorsparkstothec

2、orrectcylinder0ftheengineatthepropertimeinitsoperatingcycleformostefficientcombustion．Theresultofthesesparks，ofcourse，isignitionoftheair—fuelmixturewithineach0fthecombustionchambers.Modernignitionsystemsoperatefromabattery．Conventionalsystemsconsistofth

3、ebattery,ignitioncoil，distributor,condenser,ignitionswitch，sparkplugs，resistorandnecessarylowandhightensionwiring．Thebatteryistheheatofthetotalelectricalsystem．Inregardtotheprimarycircuit,itsfunctionistosupplyvoltageandcurrentflowtotheprimarywindingsoft

4、heignitioncoil．inordertoproduceanelectromagnet．Theprimarysideoftheignitioncoilconnectsinseriesbetweentheresistorandthebreakerpoints·Thefunctionofthiscoilwhencurrentpassesthroughitistocreateaverystrongp83electromagneticfield.Inotherwords,thecoilbecomesan

5、electromagnetwithNandSpoles.Themagneticfieldfromthiscoil,inturn,inducesavoltageinthesecondarywindingsthatisnecessarytocauseanarcatthesparkpluggap.Thesecondaryignitioncircuitnotonlytransformsthe6or12voltsofthebatterytoavoltagehighenoughtocauseanarcatthes

6、parkplugbutalsodeliversthishigh-voltagesurgetothesparkplugs.Theautomotivebatterysupplieseither6or12voltstotheprimarycoilwindings.Butthevoltagenecessarytojumpacrossthesparkplugairgapandignitetheair-fuelmixturecanrangefrom5000to25000voltsormore,dependingu

7、pontheengine'soperatingconditionatanygiventime.Theignitiondistributorhasseveralfunctions.Itopensandclosestheprimaryignitioncircuit.Itdistributesthehightensioncurrenttotherespectivecylindersoftheengine.Italsohasamechanismthatcontrolsthepointatwhichthebre

8、akerpointsopen,therebyadvancingorretardingthesparkinaccordancewithenginerequirements.Thedistributorcapandrotorreceivethehigh-voltagesurgefromthesecondarycoilwindingsthroughahigh-tensionwire.Thissurgeentersthedistributorcapthrough