《汽车理论》课程教学课件（英文讲稿）第1章 汽车动力性 Acceleration Performance 1.3 Tractive Force & Driving Resistance—Speed Characteristics and Dynamic Characteristics（驱动力-行驶阻力平衡图与动力特性图）

$ 1.3 Tractive Force & Driving Resistance--SpeedCharacteristics and Dynamic Characteristics（驱动力-行驶阻力平衡图与动力特性图）l.Tractive Force & Driving Resistance-Speed CharacteristicsFromDriving EquationF=F,+Fw+F+F1F=Ff, +Fwwhen level road & constant speed(DrivingResistancecomprisesof FrandFw)Chapter1 AccelerationPerformance

Chapter 1 Acceleration Performance §1.3 Tractive Force & Driving Resistance—Speed Characteristics and Dynamic Characteristics （驱动力-行驶阻力平衡图与动力特性图） 1. Tractive Force & Driving Resistance—Speed Characteristics From Driving Equation: when level road & constant speed （Driving Resistance comprises of Ff and FW） F F F F F t f W i j      F F F t f W   1

TqioignrF:F, =GfFFtFw=CAu21.15Ft3F, +EwFt4ukm/hu.,TractiveForce &DrivingResistanceSpeedCharacteristics2Chapter1AccelerationPerformance

Chapter 1 Acceleration Performance Tractive Force & Driving Resistance—Speed Characteristics Ft1 Ft 2 Ft3 Ft 4 F F f W  Ff a u ua ，km/ h F Gf f  tq g T 0 t T i i F r   2 21.15 D a W C Au F  Ft 2

FFtlFt3Ff +EwFt4km/ hu.3Chapter1AccelerationPerformance

Chapter 1 Acceleration Performance Ft1 Ft 2 Ft3 Ft 4 F F f W  ua ，km/ h Ft 3

TractiveForce&DrivingResistanceSpeedCharacteristics ofAudi-A4800070006000Ft15000Ft2Ft3Z4000Ft4AFt53000Ft6Ff+Fw2000100010203050607080010011012013014015016017018019020021022023024025026027028029030031040u. /(km·h-l)Chapter1 AccelerationPerformance

Chapter 1 Acceleration Performance 0 1000 2000 3000 4000 5000 6000 7000 8000 0 1 0 2 0 3 0 4 0 5 0 6 0 7 0 8 0 9 0 100 110 120 130 140 150 160 170 180 190 200 210 220 230 240 250 260 270 280 290 300 310 ua/(km/h) F /N Ft1 Ft2 Ft3 Ft4 Ft5 Ft6 Ff+Fw 1 a u /(km h )   Tractive Force & Driving Resistance— Speed Characteristics of Audi-A4 4

(1)MaximumVehicleSpeed(km/h)Uamax(> uamax is the corresponding x-coordinate of the crosspoint of the driving resistance curve and thetractive force curve of the highest gear.F. = 0uamaxF=05Chapter1AccelerationPerformance

Chapter 1 Acceleration Performance （1）Maximum Vehicle Speed——uamax(km/h)  uamax is the corresponding x-coordinate of the cross point of the driving resistance curve and the tractive force curve of the highest gear. max 0 0 i a j F u F       5

TractiveForce&DrivingResistanceSpeed Characteristics of Audi-A4800070006000Ft15000Ft2Ft3Z4000Ft4AFt53000Ft6Ff+Fw2000100010203050607080010011012013014015016017018022023024025026027028029030031040190200210u. /(km·h-")Uamax=205km/h6Chapter1 AccelerationPerformance

Chapter 1 Acceleration Performance 0 1000 2000 3000 4000 5000 6000 7000 8000 0 1 0 2 0 3 0 4 0 5 0 6 0 7 0 8 0 9 0 100 110 120 130 140 150 160 170 180 190 200 210 220 230 240 250 260 270 280 290 300 310 ua/(km/h) F /N Ft1 Ft2 Ft3 Ft4 Ft5 Ft6 Ff+Fw uamax=205km/h 1 a u /(km h )   Tractive Force & Driving Resistance— Speed Characteristics of Audi-A4 6

(2) Acceleration timeT=α=03.53.0driving on the level road2.5(z-s.w)/Ddu2.0SoIIF=F,+F+omM1.5dtIII1.0du1VIV(F, + Fw))Ha=0.5dtSm050100150ua/ (km-h-l)-a-dua41uaa31a21a0WaChapter1AccelerationPerformance

Chapter 1 Acceleration Performance （2）Acceleration time T   0 driving on the level road So 7 1 [ ( )] t f W t f W du F F F m dt du a F F F dt m          du a T u u  2 1 1    du a dt 1

(2)Acceleration timeaNAu4a41424△uAu, →AT0uaAu, →△T,Howtocalculate T whichistheIevaluation index of acceleration ability?ZAT8Chapter1AccelerationPerformance

Chapter 1 Acceleration Performance （2）Acceleration time How to calculate T which is the evaluation index of acceleration ability? T u T u T          2 2 1 1  8

Acceleration ability analyses7000600000Ft2Ft3Z4000F+4F+5300cF+6+F2000300310u,/(kmh-)> The acceleration ability changeswiththe change of gear>Highergear leads to loweracceleration ability> Changing the position of pedal make the constant speed drivepossible because the tractive force-speed curve would move upanddown vertically with the change of injection system. (the force-speedcurves shown above is the upper limit ones of the vehicle)9Chapter1 AccelerationPerformance

Chapter 1 Acceleration Performance Acceleration ability analyses  The acceleration ability changes with the change of gear.  Higher gear leads to lower acceleration ability.  Changing the position of pedal make the constant speed drive possible because the tractive force-speed curve would move up and down vertically with the change of injection system. (the force-speed curves shown above is the upper limit ones of the vehicle) 9

(tg αmax(3)MaximumGradeability1maxAB The maximum uphill grade resistance which thevehiclecouldovercome一F：（坡度阻力）AB=Gsinα.=i=αm.maxmaxmaxF,-(F, +F))F=tan3arcsinFmaxt1GOFt3F, +EWFt4Bukm/ huamaxa10Chapter1AccelerationPerformance

Chapter 1 Acceleration Performance （3）Maximum Gradeability—— —The maximum uphill grade resistance which the vehicle could overcome — Fi（坡度阻力） max max max AB  Gsin  i AB 10 Ft1 Ft 2 Ft3 Ft 4 F F f W  u km h uamax a ， / max ( ) tan sin[ ] F F F t f w i arc G        t   F A B ( ) max  max i tg