《汽车理论》课程教学课件（英文讲稿）第1章 汽车动力性 Acceleration Performance 1.4 Traction-Limited Acceleration and Adhesion Ratio汽车行驶的驱动-附着条件和附着率

（3）Traction-limitedAcceleration（驱动附着条件-充分必要条件）: Fx2 = F, - Ff2 ≤ pFz2→ F,≤(f +β)Fz2and f <<Φ.:. F ≤@Fz2 = FQF,+Fw+F≤F≤F16Chapter1AccelerationPerformance

Chapter 1 Acceleration Performance （3）Traction-limited Acceleration (驱动附着条件-充分必要条件) F F F F F f W i t      2 2 2 2 2 ( ) X t f Z t Z t Z F F F F F f F and f F F F                6

Pmax≤0.8,Howcould off-roadvehicle climbfhinking?100%grade？越野车如何爬上100%的坡道？FF =Gsin αxmax =F, = Gβ cos αneed: F,≥Fi=100%即α=45Gocosα≥Gsinαneed :β≥1Chapter1 AccelerationPerformance

Chapter 1 Acceleration Performance sin  FXmax  Fi  G G  cos F F   i need: G cos  G sin  need : 1 ≥ o i   100% 45 即 ， How could off-road vehicle climb 100% grade？越野车如何爬上100％的坡道？ max Thinking?   0.8 F  7

2.AdhesionRatio（附着率）(1)Define:Te驱动轮上的道路切向反力K10驱动轮上的道路垂直反力(When front wheel is the driving wheel)FnFy(When rearwheelisthedrivingwheel)2Fz2Note:FX2H≤F= Fz。β= Fz2 β=≤β=C≤βX1Fz2So C.isthe minimum coefficient offriction whichvehicleneededtousedrivingadequately.（附着率是汽车充分发挥驱动力作用时要求的最低附着系数。8Chapter1 AccelerationPerformance

Chapter 1 Acceleration Performance 2. Adhesion Ratio（附着率） （1） Define: Z F F X C      驱动轮上的道路切向反力 驱动轮上的道路垂直反力 X1 1 Z1 F F C  （When front wheel is the driving wheel） X2 2 Z2 F F C  （When rear wheel is the driving wheel） Note: 2 2 2 2 2 X X Z Z Z F F F F F C F ≤              ≤ ≤ So Cφ is the minimum coefficient of friction which vehicle needed to use driving adequately. (附着率是汽车充分发挥驱 动力作用时要求的最低附着系数。) 8