汽车理论作业.docx
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汽车理论作业.docx
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汽车理论作业
汽车理论作业
姓名:
陈洪平
学号:
021100701
班级:
车辆一班
1.3解:
(1)绘制驱动力与行驶阻力平衡图的Matlab程序:
i0=5.83;r=0.367;nt=0.85;m=3880;g=9.8;f=0.013;CdA=2.27;ig=[6.093.091.711];
n=600:
1:
4000;
ua=0:
1:
120;
ua1=0.377.*r.*n./ig
(1)./i0;
ua2=0.377.*r.*n./ig
(2)./i0;
ua3=0.377.*r.*n./ig(3)./i0;
ua4=0.377.*r.*n./ig(4)./i0;
N=n./1000;
Tq=-19.313+295.27.*N-165.44.*N.^2+40.874.*N.^3-3.8445.*N.^4;
Ft1=Tq.*ig
(1).*i0.*nt./r;
Ft2=Tq.*ig
(2).*i0.*nt./r;
Ft3=Tq.*ig(3).*i0.*nt./r;
Ft4=Tq.*ig(4).*i0.*nt./r;
F=m*g*f+CdA/21.15*ua.^2;
plot(ua1,Ft1,ua2,Ft2,ua3,Ft3,ua4,Ft4,ua,F);
set(gca,'XTick',[04080120]);
set(gca,'YTick',[0200040006000800010000120001400016000]);
gtext('Ft1'),gtext('Ft2'),gtext('Ft3'),gtext('Ft4'),gtext('Ff+Fw');
title('汽车驱动力-行驶阻力平衡图');
xlabel('Ua/(km/h)');
ylabel('Ft/N');
Matlab运行结果:
(2)由驱动力与行驶阻力平衡图可得
=94.93km/h
求汽车最大爬坡度是可根据公式
再根据
换算成最大爬坡度。
汽车在最大爬坡度时,其空气阻力、加速阻力、滚动阻力可忽略不计,所以附着率可简化为:
。
求最大爬坡度及其相应附着率的Matlab程序:
i0=5.83;r=0.367;nt=0.85;m=3880;g=9.8;f=0.013;CdA=2.27;L=3.2;a=1.947;hg=0.9;
ig=[6.093.091.711];
n=(600:
1:
4000);
ua1=0.377.*r.*n./ig
(1)./i0;
N=n./1000;
Tq=-19.313+295.27.*N-165.44.*N.^2+40.874.*N.^3-3.8445.*N.^4;
Ft1=Tq.*ig
(1).*i0.*nt./r;
D1=(Ft1-CdA/21.15*ua1.^2)/(m*g);
Dmax=max(D1);
amax=asin((Dmax-f.*sqrt(1-Dmax.^2+f.^2))/(1+f.^2));
imax=tan(amax);
e=imax/(a/L+hg*imax/L);
disp('汽车最大爬坡度imax=');disp(imax);
disp('相应的附着率=');disp(e);
Matlab运行结果:
汽车最大爬坡度imax=
0.3934
相应的附着率=
0.5471
(3)绘制汽车行驶加速度倒数曲线曲线的Matlab程序:
m=3880;r=0.367;nt=0.85;f=0.013;CdA=2.77;i0=5.83;If=0.218;Iw1=1.798;
Iw2=3.598;ig=[6.093.091.711];g=9.8;
n=600:
1:
4000;
ua=0:
1:
120;
O1=1+(Iw1+Iw2+If*ig
(1).^2*i0.^2*nt)/(m*r.^2);
O2=1+(Iw1+Iw2+If*ig
(2).^2*i0.^2*nt)/(m*r.^2);
O3=1+(Iw1+Iw2+If*ig(3).^2*i0.^2*nt)/(m*r.^2);
O4=1+(Iw1+Iw2+If*ig(4).^2*i0.^2*nt)/(m*r.^2);
ua1=0.377.*r.*n./ig
(1)./i0;
ua2=0.377.*r.*n./ig
(2)./i0;
ua3=0.377.*r.*n./ig(3)./i0;
ua4=0.377.*r.*n./ig(4)./i0;
N=n./1000;
Tq=-19.313+295.27.*N-165.44.*N.^2+40.874.*N.^3-3.8445.*N.^4;
Ft1=Tq.*ig
(1).*i0.*nt./r;
Ft2=Tq.*ig
(2).*i0.*nt./r;
Ft3=Tq.*ig(3).*i0.*nt./r;
Ft4=Tq.*ig(4).*i0.*nt./r;
Fw1=CdA*ua1.^2/21.15;
Fw2=CdA*ua2.^2/21.15;
Fw3=CdA*ua3.^2/21.15;
Fw4=CdA*ua4.^2/21.15;
D1=(Ft1-Fw1)/(m*g);
D2=(Ft2-Fw2)/(m*g);
D3=(Ft3-Fw3)/(m*g);
D4=(Ft4-Fw4)/(m*g);
ad1=O1./(g*(D1-f));
ad2=O1./(g*(D2-f));
ad3=O1./(g*(D3-f));
ad4=O1./(g*(D4-f));
plot(ua1,ad1,ua2,ad2,ua3,ad3,ua4,ad4);
axis([0100010]);
title('汽车的加速度倒数曲线');
xlabel('ua');
ylabel('1/a');
gtext('1/a1');gtext('1/a2');gtext('1/a3');gtext('1/a4');
Matlab运行结果:
求2档起步加速行驶至70km/h的加速时间的Matlab程序:
m1=2000;m2=1800;m=3880;r=0.367;nt=0.85;f=0.013;CdA=2.77;i0=5.83;
If=0.218;Iw1=1.798;Iw2=3.598;Ig=[6.093.091.711];g=9.8;
fori=1:
3401;
forj=1:
4;
n(i)=i+599;
ua(i,j)=0.377*r*n(i)./(Ig(j)*i0);
O(j)=1+(Iw1+Iw2)/(m*r.^2)+If*Ig(j).^2*i0^2*nt/(m*r.^2);
end
end
uamax=max(ua);uamin=min(ua);
ua2=uamin
(2):
uamax
(2);
n=ua2*i0*Ig
(2)/(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;
Ft2=Tq*i0*Ig
(2)*nt/r;
F2=m*g*f+CdA*ua2.^2/21.15;
ad2=(Ft2-F2)./(O
(2)*m);
t2=trapz(ua2,1./ad2)/3.6;
ua3=uamax
(2):
uamax(3);
n3=ua3*i0*Ig(3)/(0.377*r);
Tq3=-19.313+295.27*(n3/1000)-165.44*(n3/1000).^2+40.874*(n3/1000).^3-3.8445*(n3/1000).^4;
Ft3=Tq3*i0*Ig(3)*nt/r;
F3=m*g*f+CdA*ua3.^2/21.15;
ad3=(Ft3-F3)./(O(3)*m);
t3=trapz(ua3,1./ad3)/3.6;
ua4=uamax(3):
70;
n4=ua4*i0*Ig(4)/(nt*r);
Tq4=-19.313+295.27*(n4/1000)-165.44*(n4/1000).^2+40.874*(n4/1000).^3-3.8445*(n4/1000).^4;
Ft4=Tq4*5.83*Ig(4)*nt/r;
F4=m*g*f+CdA*ua4.^2/21.15;
ad4=(Ft4-F4)./(O(4)*m);
t4=trapz(ua4,1./ad4)/3.6;
t=t2+t3+t4
Matlab运行结果:
t=27.6350。
所以汽车2档起步加速行驶至70km/h的加速时间为27.6350s
2.7解
(1)绘制汽车功率平衡图的Matlab程序:
i0=5.83;r=0.367;nt=0.85;m=3880;g=9.8;f=0.013;CdA=2.27;ig=[6.093.091.711];
n=600:
1:
4000;
ua=0:
0.1:
120;
ua1=0.377.*r.*n./ig
(1)./i0;
ua2=0.377.*r.*n./ig
(2)./i0;
ua3=0.377.*r.*n./ig(3)./i0;
ua4=0.377.*r.*n./ig(4)./i0;
N=n./1000;
Tq=-19.313+295.27.*N-165.44.*N.^2+40.874.*N.^3-3.8445.*N.^4;
Ff=m*g*f;
Fw=CdA*ua.^2/21.15;
Pf=Ff*ua/3600;
Pw=Fw.*ua/3600;
Pe0=(Pf+Pw)./nt;
Pe1=Tq.*ig
(1)*i0.*ua1./(3600*r);
Pe2=Tq.*ig
(2)*i0.*ua2./(3600*r);
Pe3=Tq.*ig(3)*i0.*ua3./(3600*r);
Pe4=Tq.*ig(4)*i0.*ua4./(3600*r);
Pe=max(Pe1);
plot(ua1,Pe1,ua2,Pe2,ua3,Pe3,ua4,Pe4,ua,Pe0,ua,Pe);
title('汽车功率平衡图');
xlabel('ua/(km/h)');
ylabel('Pe/kw');
gtext('1'),gtext('2'),gtext('3'),gtext('4'),gtext('(Pf+Pw)/nt'),gtext('Pe');
Matlab运行结果:
(2)绘制最高档与次高档的等速百公里油耗曲线的Matlab程序:
m=3880;g=9.8;r=0.367;nt=0.85;f=0.013;CdA=2.77;i0=5.83;pg=7.1;
ig=[6.093.091.711];
n=600:
1:
4000;
n0=[8151207161420122603300634033804];
B00=[1326.81354.71284.41122.91141.01051.21233.91129.7];
B10=[-416.46-303.98-189.75-121.59-98.893-73.714-84.478-45.291];
B20=[72.37936.65714.5247.00354.47632.85932.97880.71113];
B30=[-5.8629-2.0553-0.51184-0.18517-0.091077-0.05138-0.047449-0.00075215];
B40=[0.177680.0430720.00681640.00185550.000689060.000350320.00028230-0.000038568];
B0=spline(n0,B00,n);
B1=spline(n0,B10,n);
B2=spline(n0,B20,n);
B3=spline(n0,B30,n);
B4=spline(n0,B40,n);
ua3=0.377*r*n/ig(3)/i0;
ua4=0.377*r*n/ig(4)/i0;
Ff=m*g*f;
Fz3=Ff+CdA*(ua3.^2)/21.15;
Fz4=Ff+CdA*(ua4.^2)/21.15;
Pe3=Fz4.*ua3./(nt*3.6*1000);
Pe4=Fz4.*ua4./(nt*3.6*1000);
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