汽车理论课后习题13

解：1)

»clearall

»f=0.013;G=38800;Ff=G*f;CdA=2.77;ul=0:1:120;Fw=CdA.*u1.A2/21.15;F=Ff+Fw;Ig=[5.56

2.7691.6441.0000.793];k=l:5;

»ngk=[600600600600600];

»ngm=[40004000400040004000];

»r=0.367;I0=5.83;eta=0.85;

»ugk=0.377*r*ngk(k)./(Ig(k).*I0);

»ukm=0.377.*r.*ngm(k)./(Ig(k).*I0);

»fork=l:5

u=ugk(k):ukm(k);

n=Ig(k)*I0.*u./r/0.377;

Tq=-19.313+295.27*n/1000-165.44*(n/1000).A2+40.874*(n/1000).A3-3.8445*(n/1000).A4;

Ft=Tq.*Ig(k)*I0*eta/r;

plot(u,Ft,ul,F)

holdon,gridon

end

2）最高车速求解程序:

»

[n,u]=solve(,n=u*0.793*5.83/(0.377*0.367),,,(-19.3I3+295.27*(n/1000)-165.44*(n/1000)A2+40.8

74*(n/1000)八3・3.8445*(n/1000)八4)*0.793*5.83*0.85/0.367・(2.77*u八2/21.15+3880*10*0.013))

3299.9224534468163066899978278864

264.13689338171544956471411061266

3533.8761660967238474546442908623+2707.8751259314497120563837339829*1

3533.8761660967238474546442908623-2707.8751259314497120563837339829*i

u=

98.757345195946534184690962185964

7.9048701073070256438355939579073

105.75891807712350450878660177051+81.039043290184796798403093329529*i

105.75891807712350450878660177051-81.039043290184796798403093329529*1

分析：u的后三个解明显不符合题意，所以最高车速是98.757km/h

求最大爬坡度和最大附着系数

>>1=0.218;Iwl=1.798;Iw2=3.598;L=3.2;m=3880;r=0.367;

»eta=0.85;Cd=2.77;f=0.013;i0=5.83;a=1.947;hg=0.9;

»g=10;ig=[5.56;2.769;1.644;1.00;0.793];

»fori=l:5

th(i)=l+(Iwl+Iw2)/(m*rA2)+(I*i0A2+(ig(i)A2*eta))/(m*rA2);

end

»fbri=l:5

ual(i,l)=(600*0.377*r)/(ig(i)*i0);

ual(i,2)=(4000*0.377*r)/(ig(i)*i0);

end

»ua=ual(1,1):.Ol:ual(l,2);

»[x,y]=size(ua);

»fbri=l:y

n=ua(i)*ig(l)*i0/(0.377*r);

Tq=-19.313+295.27*(n/1000)-165.44*(n/1000)A2+40.874*(n/1000)A3-3.8445*(n/1000)A4;

Ft(i)=Tq*ig(l)*iO*eta/r;

Fw(i)=Cd*ua(i)A2/21.15;

Fc(i)=Ft(i)-Fw(i)

end

>>plot(ua,Ft/1000,':',ua,Fc/1000，',ua,Fw/1000,'」)

»D=max(Fc)/m/g;

»af=asin((D-f*sqrt(l+fA2-DA2))/(l+fA2));

»i=tan(af)；

»q=i；

»cf2=q/(a/L+q*hg/L);

»i

0.3448

»cf2

cf2=

0.4888

3)

»clc

clear

1=0.218;Iwl=1.798;Iw2=3.598;L=3.2;m=3880;r=0.367;eta=0.85;

Cd=2.77;f=0.013;i0=5.83;a=1.947;hg=0.9;

g=10;ig=[5.56;2.769;1.644;1.00;0.793];

umax=96;

fori=l:5

th(i)=l+(Iwl+Iw2)/(m*rA2)+(I*iOA2+(ig(i)A2*eta))/(m*rA2);

end

fori=l:5

ual(i,l)=(600*0.377*r)/(ig(i)*i0);

if(4000*0.377*r)/(ig(i)*i0)<umax

ual(i,2)=(4000*0.377*r)/(ig(i)*i0);

else

ual(i,2)=umax;

end

end

forj=l:5

ua=ual(j,1):ual(j,2);

[x,y]=size(ua);

fori=l:y

n=ua(i)*ig(j)*i0/(0.377*r);

Tq=-19.313+295.27*(n/1000)-165.44*(n/1000)A2+40.874*(n/1000)A3-3.8445*(n/1000)A4;

Ft=Tq*ig(j)*iO*eta/r;

Fz=Cd*ua(i)A2/21.15+m*g*f;

a(i)=(th(j)*m)/(Ft-Fz);

end

plot(ua,a,'-r')

holdon

end

»clc

clear

%定义个变量值：

1=0.218;Iwl=1.798;Iw2=3.598;L=3.2;m=3880;r=0.367;

eta=0.85;Cd=2.77;f=0.013;i0=5.83;a=1.947;hg=0.9;

g=10;ig=[5.56;2.769;1.644;1.00;0.793];

%求出各档所对应加速质量系数

fbri=l:5

th(i)=l+(Iwl+Iw2)/(m*rA2)+(I*iOA2+(ig(i)A2*eta))/(m*rA2);

end

umax=99;

%求出各档在最大车速范围内稳定转速所对应的速度

fori=l:5

ual(i,l)=(600*0.377*r)/(ig⑴*i0);

if(4000*0.377*r)/(ig(i)*i0)<umax

ual(i,2)=(4000*0.377*r)/(ig(i)*i0);

else

ual(i,2)=umax;

end

end

%从二档到五档按照A方法选取合适加速度

foru=l:98

if(u<ual(2,l))

a(u)=0

elseif(u<=ual(2,2))%当在二档ua内的加速度倒数

n=u*ig(2)*i0/(0.377*r);

Tq=-19.313+295.27*(n/1000)-165.44*(n/1000)A2+40.874*(n/1000)A3-3.8445*(n/1000)A4;

Ft=Tq*ig(2)*iO*eta/r;

Fz=Cd*u八2/21.15+m*g*f;

a(u)=(th(2)*m)/(Ft-Fz);

elseif(u<=ual(3,2))%在二档最大速度到三档最大速度内加速度倒数

n=u*ig(3)*i0/(0.377*r);

Tq=-19.313+295.27*(n/l000)-165.44*(n/l000)八2+40.874*(n/1000)A3-3.8445*(n/1000)A4;

Ft=Tq*ig(3)*i0*eta/r;

Fz=Cd*uA2/21.15+m*g*f;

a(u)=(th(3)*m)/(Ft-Fz);

elseif(u<=ual(4,2))%在三档最大速度到四档最大速度内加速度倒数

n=u*ig(4)*i0/(0.377*r);

Tq=-19.313+295.27*(n/1000)-165.44*(n/1000)A2+40.874*(n/1000)A3-3.8445*(n/1000)A4;

Ft=Tq*ig(4)*iO*eta/r;

Fz=Cd*uA2/21.15+m*g*f;

a(u)=(th(4)*m)/(Ft-Fz);

elseif(u<=ual(5,2))%在四档最大速度到五档最大速度内加速度倒数

n=u*ig(5)*i0/(0.377*r);

Tq=-19.313+295.27*(n/1000)-165.44*(n/1000)A2+40.874*(n/1000)A3-3.8445*(n/1000)A4;

Ft=Tq*ig(5)*i0*eta/r;

Fz=Cd*uA2/21.15+m*g*f;

a(u)=(th(5)*m)/(Ft-Fz);

end

end

end

end

end

end

ux=l:ual(2,l);

%给低速无意义阶段的速度赋予5km/h时同样的加速度

[x,y]=size(ux);

fori=l:y

a(i)=a(y+l)

end

t=0;

u=l:98;

fori=1:98

t=t+l/3.6*a⑴;％图解积分法求解时间

ts(i)=t;

end

plot(ts,u)

title(速度时间图,)

ylabel(,ua(km/h)')

xlabeK'tCs)')

text(33,70,'\leftarrow70km/h加速时间)

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速度时间图

100

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