汽车理论课后习题

1、精选优质文档-倾情为你奉上第二次作业 车辆工程 八班 胡文贵 解：汽车功率平衡图程序>> clear all>> f=0.013; G=38800;Ff=G*f; CdA=2.77;u1=0:1:120; Fw=CdA.*u1.2/21.15;F=Ff+Fw;Ig=5.56 2.769 1.644 1.000 0.793;k=1:5;>> ngk=600 600 600 600 600;>> ngm=4000 4000 4000 4000 4000;>> r=0.367;I0=5.83;eta=0.85;>> ugk=0.

2、377*r*ngk(k)./(Ig(k).*I0);>> ukm=0.377.*r.*ngm(k)./(Ig(k).*I0);>> pz=F.*u1./3600;>> for k=1:5u=ugk(k):ukm(k);n=Ig(k)*I0.*u./r/0.377; Tq=-19.313+295.27*n/1000-165.44*(n/1000).2+40.874*(n/1000).3-3.8445*(n/1000).4;Ft=Tq.*Ig(k)*I0*eta/r;pe=Ft.*u./3600;plot(u1,pz,u,pe)hold on,grid onen

3、d2)最高档和次高档百公里油耗曲线>> n=600:1:4000;m=3880;g=9.8;G=m*g;ig=5.56 2.769 1.644 1.00 0.793;nT=0.85;r=0.367;f=0.013;CDA=2.77;i0=5.83;L=3.2;a=1.947;hg=0.9;If=0.218;Iw1=1.798;Iw2=3.598;n0=815 1207 1614 2012 2603 3006 3403 3804;B00=1326.8 1354.7 1284.4 1122.9 1141.0 1051.2 1233.9 1129.7;B10=-416.46 -303.9

4、8 -189.75 -121.59 -98.893 -73.714 -84.478 -45.291;B20=72.379 36.657 14.524 7.0035 4.4763 2.8593 2.9788 0.71113;B30=-5.8629 -2.0553 -0.51184 -0.18517 -0. -0.05138 -0. -0.;B40=0.17768 0. 0. 0. 0. 0. 0. -0.;B0=spline(n0,B00,n);B1=spline(n0,B10,n);B2=spline(n0,B20,n); B3=spline(n0,B30,n);B4=spline(n0,B4

5、0,n);Ff=G*f;ua4=0.377*r*n/ig(4)/i0;ua5=0.377*r*n/ig(5)/i0;Fz4=Ff+CDA*(ua4.2)/21.15;Fz5=Ff+CDA*(ua5.2)/21.15;Pe4=Fz4.*ua4./(nT*3.6*1000);Pe5=Fz5.*ua5./(nT*3.6*1000);>> for i=1:1:3401 b4(i)=B0(i)+B1(i)*Pe4(i)+B2(i)*Pe4(i).2+B3(i)*Pe4(i).3+B4(i)*Pe4(i).4;b5(i)=B0(i)+B1(i)*Pe5(i)+B2(i)*Pe5(i).2+B3

6、(i)*Pe5(i).3+B4(i)*Pe5(i).4;endpg=7.0;Q4=Pe4.*b4./(1.02.*ua4.*pg); Q5=Pe5.*b5./(1.02.*ua5.*pg);plot(ua4,Q4,ua5,Q5);axis(0 100 10 30);title('最高档与次高档等速百公里油耗曲线');xlabel('ua(km/h)');ylabel('百公里油耗（L/100km）');gtext('4'),gtext('5');六工况油耗计算1）匀速25km/h>> f=0.013;

7、G=38800;Ff=G*f; CdA=2.77;eta=0.85;ua=25;>> pe=(Ff*ua+CdA*ua.3/21.15)/(eta*3600)pe =4.7897>> r=0.367;I0=5.83;Ig=5.56 2.769 1.644 1.000 0.793;>> for i=1:5 n=ua*Ig(i)*I0/(0.377*r)tq=-19.313+295.27*n/1000-165.44*(n/1000).2+40.874*(n/1000).3-3.8445*(n/1000).4P=tq*n/9550end利用matlab求出的结果n

8、 =5.8570e+03 tq =-276.9876 P = -169.8763n =2.9169e+03 tq =170.4435 P =52.0596n =1.7318e+03 tq =173.5743 P =31.4764 n =1.0534e+03 tq =151.1890 P =16.6770n =835.3613 tq = 133.8503 P =11.7082由于国标规定，尽量用最高档行驶。而阻力功率>> f=0.013; G=38800;Ff=G*f; CdA=2.77;eta=0.85;ua=25;>> pe=(Ff*ua+CdA*ua.3/21.15

9、)/(eta*3600)pe =4.7897所以时速25km/h时可以使用五档行驶此时，n =835.3613 tq = 133.8503 P =11.7082利用插值法n=835;k=(835-815)/(1207-835);>> B1=1326.8 -416.46 72.379 -5.8629 0.17768;B2=1354.7 -303.98 36.657 -2.0553 0.;>> for i=1:5 x(i)=(k*B2(i)+B1(i)/(k+1)end>> p=11.7082;b=x(1)+x(2)*p+x(3)*p.2+x(4)*p.3+x(

10、5)*p.4b = 303.1827取汽油的pg值为6.69>> pg=6.69;Qt=p*b/(367.1*pg); Q=p*b*50/(102*25*pg)Q = 10.4039ml2）匀速40同理可求得用第五档匀速n =1.3366e+03 tq = 165.1160 P = 23.1089n=1337; k=(n-1207)/(1614-n);>> B2=1354.7 -303.98 36.657 -2.0553 0.;B3=1284.4 -189.75 14.524 -0.51184 0.;>> for i=1:5 x(i)=(k*B3(i)+B2

11、(i)/(k+1)end>> p=23.1089;b=x(1)+x(2)*p+x(3)*p.2+x(4)*p.3+x(5)*p.4b = 652.0141>> pg=6.69;Qt=p*b/(367.1*pg); Q=p*b*250/(102*25*pg)Q = 220.8055ml3）匀速50km/h同理可求得用第五档匀速n =1.6707e+03 tq = 172.8685 P = 30.2424>> n=1671;k=(n-1614)/(2012-n);>> B4=122.9 -121.59 7.0035 -0.18517 0.;>&

12、gt; for i=1:5 x(i)=(k*B4(i)+B3(i)/(k+1)end>> p = 30.2424;b=x(1)+x(2)*p+x(3)*p.2+x(4)*p.3+x(5)*p.4b = 217.6389>> pg=6.69;Qt=p*b/(367.1*pg); Q=p*b*250/(102*25*pg)Q = 96.4554ml4）I=0.218; Iw1=1.798; Iw2=3.598;L=3.2; m=3880; r=0.367; eta=0.85;f=0.013; i0=5.83; a=1.947; hg=0.9; g=10; ig=5.56;2

13、.769;1.644;1.00;0.793; G=38800;Ff=G*f; ua=40;>> for i=1:5th(i)=1+(Iw1+Iw2)/(m*r2)+(I*i02+(ig(i)2*eta)/(m*r2);end>> for i=1:5 pe=(Ff*ua+CdA*ua.3/21.15+th(i)*m*ua0.25)/(3600*eta)endpe = 22.9607 pe = 22.4813 pe = 22.3789 pe = 22.3438 pe = 22.3361阻力功率比第五档、第四档25km/h行驶时功率大故可以用第三档加速r=0.367;I0=5

14、.83;Ig=1.644;>> for i=1:16n=u(i)*Ig*I0/(0.377*r)tq=-19.313+295.27*n/1000-165.44*(n/1000).2+40.874*(n/1000).3-3.8445*(n/1000).4P=tq*n/9550end>> ua=25:1:40;>> I=0.218; Iw1=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;2.76

15、9;1.644;1.00;0.793;>> for j=1:16 n(j)=ua(j)*ig(3)*i0/(0.377*r)end>> for i=1:16tq(i)=-19.313+295.27*n(i)/1000-165.44*(n(i)/1000).2+40.874*(n(i)/1000).3-3.8445*(n(i)/1000).4pe(i)=tq(i)*n(i)/9550end>> B5=1141.0 -98.893 4.4763 -0. 0.;B6=1051.2 -73.714 2.8593 -0.05138 0.;B4=1122.9 -121.

16、59 7.0035 -0.18517 0.;B3=1284.4 -189.75 14.524 -0.51184 0.;>> for i=1:16 if n(i)<2012 k(i)=(n(i)-1614)/(2012-n(i) endend>> for i=1:16 if n(i)<012 k(i)=(n(i)-1614)/(2012-n(i) for j=1:5 x(j)=(k(i)*B4(j)+B3(j)/(k(i)+1) end b(i)=x(1)+x(2)*pe(i)+x(3)*pe(i).2+x(4)*pe(i).3+x(5)*pe(i).4 el

17、seif n(i)>2603 k(i)=(n(i)-2603)/(3006-n(i) for j=1:5 x(j)=(k(i)*B6(j)+B5(j)/(k(i)+1) end b(i)=x(1)+x(2)*pe(i)+x(3)*pe(i).2+x(4)*pe(i).3+x(5)*pe(i).4 else k(i)=(n(i)-2012)/(2603-n(i) for j=1:5 x(j)=(k(i)*B5(j)+B4(j)/(k(i)+1) end b(i)=x(1)+x(2)*pe(i)+x(3)*pe(i).2+x(4)*pe(i).3+x(5)*pe(i).4endend>

18、> pg=6.96;>> for i=1:16 Qt(i)=pe(i)*b(i)/(367.1*pg) end;>> delteT=1/(3.6*0.25);>> for i=1:15 Qr(i)=(Qt(i)+Qt(i+1)*delteT/2Qa=sum(Qr)endQa = 84.82165)加速区间40-50kn/h根据计算>> I=0.218; Iw1=1.798; Iw2=3.598;L=3.2; m=3880; r=0.367; eta=0.85;f=0.013; i0=5.83; a=1.947; hg=0.9; g=10;

19、ig=5.56;2.769;1.644;1.00;0.793; G=38800;Ff=G*f;ua=50; Cd=2.77;>> for i=1:5th(i)=1+(Iw1+Iw2)/(m*r2)+(I*i02+(ig(i)2*eta)/(m*r2);end>> for i=1:5 pe=(Ff*ua+Cd*ua.3/21.15+th(i)*m*ua*0.25)/(3600*eta)end得出所需最高功率pe =30.6269而四档在车速为40km/h时所能提供的功率为P =30.5423（计算程序与上同，略）故可以使用四档加速。>> ua=40:1:50;

20、I=0.218; Iw1=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; for j=1:11 n(j)=ua(j)*ig(4)*i0/(0.377*r)end>> for i=1:11tq(i)=-19.313+295.27*n(i)/1000-165.44*(n(i)/1000).2+40.874*(n(i)/1000).3-3.8445*(n(i)/1000).4pe(i)=tq(i)*n(i)/9550end>> B5=1141.0 -98.893 4.4763 -0. 0.;B4=1122.9 -121.59 7.0035 -0.18517 0.;B3=1284.4 -189.75 14.524 -0.51184 0.;>