汽車?yán)碚揜atio行駛驅(qū)動(dòng)附著條件和率

§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（濕土路Rollingsnowroad（滾壓后的雪路 Chapter AccelerationTyreofFormula1racingdrydrytyreorIntermediatewettyre Chapter AccelerationFX2=Ft-Ff2￡jZFt￡(f+j)FZandf<<\Ft￡jZ2=FFf+FW+Fi￡Ft￡ Chapter Accelerationjmax￡jmax￡0.8，Howcouldoff-roadvehicleclimb100%grade？越野車如何爬上100％的坡道？ Chapter AccelerationAdhesionRatio（附著率

=

（Whenfrontwheelisthedriving（WhenrearwheelisthedrivingCCj=F≤F=jXXjZFjZSoCφistheminimumcoefficientoffrictionwhichvehicleneededtousedrivingadequa Chapter Accelerationnoteasytomeettheneedsoflimitedcondition→whichnoteasytomeettheneedsoflimitedcondition→whichFX1frontwheelisthedrivingwheelFX1↓、FZ1↑、Cφ1easytomeettheneedsoflimitedgoodroadgoodroadcondition，ua↓，F(xiàn)f↓；Fw↓flatroad，F(xiàn)ismoothacceleration，F(xiàn)jstandingstartoniceandsnowroad→highgearorlowbeinhighgearandstepacceleratorpedalslightlyslickroad濕滑路面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第四節(jié)第四節(jié)Thinking：Thinking：whatisideadrivingAllWheels Chapter Accelerationsupersupercarua↑，F(xiàn)W↑；Bigenginecement，F(xiàn)tWhichWhichtypevehiclefitsLimousineCarm↑，F(xiàn)f↑；ua↑，bigcarbody，F(xiàn)W↑Bigengine cement發(fā)動(dòng)機(jī)排量，F(xiàn)toff-roadoff-roadvehiclenotgoodroadheavyheavygoodsvehiclem↑，F(xiàn)f↑；notgoodroad Chapter AccelerationF=12F=12ArurFZw2=12LrArurF=--Gduhg FZ=Zs-Zw2+Gduhg Note:CLfisthecoefficientof forCLristhecoefficientof forthepartproducedbyrolling torque:thispartisverysmallandisignored. Chapter AccelerationCoefficientofTheheightofairdamskirt(前阻風(fēng)板andrearspoiler(后擾流板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