基于matlab来确定一轻型五档货车的动力性

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确定以轻型五档货车的动力性：

解：1.绘制汽车驱动力与行驶阻力平衡图

Matlab 编写程序如下

n=600:4000; r=0.367; nt=0.85; f=0.013; CA=2.77; io=5.83; m=3880; g=9.8; Tq=-19.313+295.27.*n./1000-165.44.*(n./1000).^2+40.874.*(n./1000).^3-3.8445.*(n./1000).^4;

ig1=5.56; Ua1=0.377.*r.*n./(ig1.*io); Ft1=Tq.*ig1.*io.*nt./r;

ig2=2.769; Ua2=0.377.*r.*n./(ig2.*io); Ft2=Tq.*ig2.*io.*nt./r;

ig3=1.644; Ua3=0.377.*r.*n./(ig3.*io); Ft3=Tq.*ig3.*io.*nt./r;

ig4=1.00; Ua4=0.377.*r.*n./(ig4.*io); Ft4=Tq.*ig4.*io.*nt./r;

ig5=0.793; Ua5=0.377.*r.*n./(ig5.*io); Ft5=Tq.*ig5.*io.*nt./r;

Fr=m.*g.*f+(CA/21.15).*Ua5.^2;

plot(Ua1,Ft1,Ua2,Ft2,Ua3,Ft3,Ua4,Ft4,Ua5,Ft5,Ua5,Fr);

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Ua(Km/h)F t (K N )驱动力行驶阻力平衡图

2.求最高车速，最大爬坡度及相应附着率

2.1 最高车速Uamax

function Uamax=Uamax(Ua5)

r=0.367; nt=0.85; f=0.013; CA=2.77; io=5.83; m=3880; g=9.8;ig5=0.793; n=Ua5.*ig5.*io./(0.377.*r);

Tq=-19.313+295.27.*n./1000-165.44.*(n./1000).^2+40.874.*(n./1000).^3-3.8445.*(n./1000).^4;

Ft5=Tq.*ig5.*io.*nt./r;

Fr=m.*g.*f+(CA/21.15).*Ua5.^2;

Uamax=Ft5-Fr;

>> x=fzero(@Uamax,99)

x =

99.0834

2.2 最大爬坡度 imax

r=0.367; nt=0.85; f=0.013; CA=2.77; io=5.83; m=3880; g=9.8;

Tq=-19.313+295.27.*n./1000-165.44.*(n./1000).^2+40.874.*(n./1000).^3-3.8445.*(n./1000).^4;

ig1=5.56; Ua1=0.377.*r.*n./(ig1.*io);

i=(Tq.*ig1.*io.*nt./r-m.*g.*f)./(m.*g);

imax=m>> imax

imax =

0.3325

2.3 该爬坡度时的附着率Co

>> a=1.947; L=3.2; hg=0.9; q=0.3325;

Co=q./(a./L+hg.*q./L)

Co =

0.4737

3.绘制加速度倒数曲线，计算二档起步加速至70Km/s 的时间

Matlab 编写程序如下

n=600:4000; r=0.367; nt=0.85; f=0.013; CA=2.77; io=5.83; m=3880; g=9.8; Iw1=1.798; Iw2=3.598; If=0.218;

Tq=-19.313+295.27.*n./1000-165.44.*(n./1000).^2+40.874.*(n./1000).^3-3.8445.*(n./1000).^4;

ig1=5.56; Ua1=0.377.*r.*n./(ig1.*io); inv_a1=(m+(Iw1+Iw2)./r.^2+(If.*ig1.^2.*io.^2.*nt)./r.^2)./(Tq.*ig1.*io.*nt./r-m.*g.*f-(CA./21.15).*Ua1.^2);

ig2=2.769; Ua2=0.377.*r.*n./(ig2.*io);

inv_a2=(m+(Iw1+Iw2)./r.^2+(If.*ig2.^2.*io.^2.*nt)./r.^2)./(Tq.*ig2.*io.*nt./r-m.*g.*f-(CA./21.15).*Ua2.^2);

ig3=1.644; Ua3=0.377.*r.*n./(ig3.*io); inv_a3=(m+(Iw1+Iw2)./r.^2+(If.*ig3.^2.*io.^2.*nt)./r.^2)./(Tq.*ig3.*io.*nt./r-m.*g.*f-(CA./21.15).*Ua3.^2);

ig4=1.00; Ua4=0.377.*r.*n./(ig4.*io); inv_a4=(m+(Iw1+Iw2)./r.^2+(If.*ig4.^2.*io.^2.*nt)./r.^2)./(Tq.*ig4.*io.*nt./r-m.*g.*f-(CA./21.15).*Ua4.^2);

ig5=0.793; Ua5=0.377.*r.*n./(ig5.*io); inv_a5=(m+(Iw1+Iw2)./r.^2+(If.*ig5.^2.*io.^2.*nt)./r.^2)./(Tq.*ig5.*io.*nt./r-m.*g.*f-(CA./21.15).*Ua5.^2);

axis([0 80 0 10]);

plot(Ua1,inv_a1,Ua2,inv_a2,Ua3,inv_a3,Ua4,inv_a4,Ua5,inv_a5);

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加速度倒数曲线