仪表及指示系统

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1、Chapter7InstrumentandIndicatorSystem1.InstrumentsystemInstrumentsystemisusedtoindicatetheoperatingconditionofengineandvehicle.Itincludesvariousmetersorgaugesontheinstrumentpanel,suchas:•speedometer•odometer•tripodometer•tachometer•coolanttemperaturegauge•ampereme

2、ter(orvoltmeter)•fuelgauge•oilpressuregauge•airpressuregauge(forairpressurebrakingsystem),etc・2.IndicatorsystemIndicatorsystemisusuallyusedtomonitortheabnormalorlimitedoperatingconditionofengineandvehicle.Itincludesvariouswarningorindicatorlightsandchimes,suchas:

3、•Oilpressurewarninglight•Lowairpressurewarninglight(forairpressurebrakingsystem)•Lowvacuumwarninglight(forvacuumbrakebooster)•Lowbrakefluidwarninglight•Brakingsignalwarninglight•Aircleanerjamwarninglight•Lowfuelwarninglight•Exhaustbrakeindicatorlight(forexhaustbr

4、akesystem)•Turnsignal/hazardindicatorlight•Highbeamindicatorlight•Chargingindicatorlight•Seatbeltreminderlight•Glowplugindicatorlight(fordieselengine)•Lowwasherfluidindicatorlight•Waterinfuelfilterwarninglight(fdrdieselengine)•Rearwindowdefoggerindicatorlight•4-w

5、heeldriveindicatorlight(for4-wheeldrivevehicle)•A/Toiltemperaturewarninglight(forautomatictransmission)•Engineoiltemperaturewarninglight,etc.3.Speedometerandodometer3.1FunctionofspeedometerandodometerSpeedometer一Itindicatesvehiclespeed.Odometer一Itrecordsthetotald

6、istancethevehiclehasbeendriven.3.2Constructionofspeedometerandodometer(magneticinductiontypeforexample)SeeFig.7-11onpage2121-permanentmagnet2-metal(aluminium)ring3-magneticscreen4・coilspring5-speedometerface6-pointer7-numberrings(decimalodometer)8,9-wormgears10-d

7、rivingshaft1.1OperatingprincipleThemagnetisdrivenbyaflexiblecablefromthetransmission.Thefasterthecargoes,thefasterthemagnetspins.Thisactionproducesarotatingmagneticfieldthatdragsonthemetalringsurroundingthemagnet.Thefasterthespinning,themoredragonthering.Thespinn

8、ingcausestheringtoswingaroundagainstthetensionofaspring.This,inturn,movesapointerattachedtothering,whichindicatescarspeed・Theodometerisoperatedbyapairofgearsfr