汽车理论作业.doc

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=6.09 3.09 1.71 1;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,0 40 80 120 );set(gca,YTick,0 2000 4000 6000 8000 10000 12000 14000 16000);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uamax=94.93km/h求汽车最大爬坡度是可根据公式max=arcsinD1max-f1-D1max2+f21+f2再根据tanmax=imax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：C=imaxaL+hgiL。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=6.09 3.09 1.71 1;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=6.09 3.09 1.71 1;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(0 100 0 10);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=6.09 3.09 1.71 1;g=9.8;for i=1:3401; for j=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*i02*nt/(m*r.2); endenduamax=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+t4Matlab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27.6350s2.7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=6.09 3.09 1.71 1;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=6.09 3.09 1.71 1;n=600:1:4000;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 -303.98 -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 -0.091077 -0.05138 -0.047449 -0.00075215;B40=0.17768 0.043072 0.0068164 0.0018555 0.00068906 0.00035032 0.00028230 -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);for i=1:1:3401 b3(i)=B0(i)+B1(i)*Pe3(i)+B2(i)*Pe3(i).2+B3(i)*Pe3(i).3+B4