汽车理论Ratio行驶驱动附着条件和率

§1.4Traction-LimitedAccelerationandAdhesionWhenLevelConstant

Fi=Fj=Levelroad&Constantspeed:Ft=Ft=Ff+FW+Fi+

dmdu=F- + +F Chapter Acceleration

Ft=Ff+FW+Ft＞Ff+FW+FiFt＜Ff+FW+

F=TtqigF=Ttqigi0hTtig›Ttq›ri0› hT›rflFttF Chapter Acceleration Presumingthereisadequatepowerfromtheengine,thebetweenthetireandroadforanti-skidpurpose.InthiscaseFφis

=FzjTt-Tf

= £

X usuallyφrangesfromFZφ——Weightondriving Chapter AccelerationAverageCoefficientofFrictionforCommonφDrygravelroad（干燥的碎石路Dryearthroad（干土路Wetearthroad（湿土路Rollingsnowroad（滚压后的雪路 Chapter AccelerationTyreofFormula1racingdrydrytyreorIntermediatewettyre Chapter AccelerationFX2=Ft-Ff2£jZFt£(f+j)FZandf<<\Ft£jZ2=FFf+FW+Fi£Ft£ Chapter Accelerationjmax£jmax£0.8，Howcouldoff-roadvehicleclimb100%grade？越野车如何爬上100％的坡道？ Chapter AccelerationAdhesionRatio（附着率

=

（Whenfrontwheelisthedriving（WhenrearwheelisthedrivingCCj=F≤F=jXXjZFjZSoCφistheminimumcoefficientoffrictionwhichvehicleneededtousedrivingadequa Chapter Accelerationnoteasytomeettheneedsoflimitedcondition→whichnoteasytomeettheneedsoflimitedcondition→whichFX1frontwheelisthedrivingwheelFX1↓、FZ1↑、Cφ1easytomeettheneedsoflimitedgoodroadgoodroadcondition，ua↓，Ff↓；Fw↓flatroad，Fismoothacceleration，Fjstandingstartoniceandsnowroad→highgearorlowbeinhighgearandstepacceleratorpedalslightlyslickroad湿滑路面iceandsnowroadsandroadnoteasytomeetthenoteasytomeettheneedsoflimitedcondition→whichworkingcondition?slamaccelerationfromstandingstart起步急加速WhenfrontwheelisthedrivingFX=X2+FX=X2+w+i+gd=f+w+i+jw+gd\FX=F2+Fw+Fi+FjWhenrearwheelisthedrivingFX2=X+w+iFX2=X+w+iF2=Ff +F +Fi+g+Fjdd d Chapter AccelerationThemechanics vehiclewithaccelerationTf

Gdug

GTf

Chapter AccelerationFFbcosaLgFZsacosaLgsinasinaFZd»FZd»-gddhLFZd»GdhgdLNote:IgnoreRotationalmassinertial Chapter AccelerationThinking：Thinking：Whichdrivingmodeeasytomeettheneedsoflimitedcondition?frontwheeldriveorrearwheeldrive?FFZd1whenrearrearreardriving→sportsPorsche911Porsche911 Chapter Acceleration第四节第四节Thinking：Thinking：whatisideadrivingAllWheels Chapter Accelerationsupersupercarua↑，FW↑；Bigenginecement，FtWhichWhichtypevehiclefitsLimousineCarm↑，Ff↑；ua↑，bigcarbody，FW↑Bigengine cement发动机排量，Ftoff-roadoff-roadvehiclenotgoodroadheavyheavygoodsvehiclem↑，Ff↑；notgoodroad Chapter AccelerationF=12F=12ArurFZw2=12LrArurF=--Gduhg FZ=Zs-Zw2+Gduhg Note:CLfisthecoefficientof forCLristhecoefficientof forthepartproducedbyrolling torque:thispartisverysmallandisignored. Chapter AccelerationCoefficientofTheheightofairdamskirt(前阻风板andrearspoiler(后扰流板affectCD、CLfandCLr. Chapter AccelerationCC=FXFf++Fi+Fj¢F=ZFGduZs-Zw-ggdtLC»Fi+Fj¢FZs-Ggduhg» cosa dt =i+ 1duqh dudt bL-g i1cosadtbLhgLqq j1+hgLa.Accelerationanduphill(frontwheeldriveq=i 1ducosgdtNoteq=i 1ducosgdtCj1›，sothejwhichvehicleneededisbigandthefrontdrivingwheeliseasytoskid. Chapter AccelerationC=C=FXF=Ff1+ZF+Fi+GdugZs-Zw+ dtL»Fi+=FZs+Gduhg dt Lqa+hgLqqaLj1-hgLifrearwheeldriveqqfrontwheeldrive＜qrearwheeldriveSothefrontdrivingwheeliseasyto Chapter Accele