汽车理论课后作业matlab编程详解(带注释)

一、确定一轻型货车的动力性能。

欧阳引擎（2021.01.01）1）绘制汽车驱动力与行驶阻力平衡图；2）求汽车最高车速与最大爬坡度；3）绘制汽车行驶加速度倒数曲线；用计算机求汽车用Ⅱ档起步加速行驶至 70km/h 所需的加速时间。

已知数据略。

（参见《汽车理论》习题第一章第3题）解题程序如下:用Matlab语言(1)绘制汽车驱动力与行驶阻力平衡图m1=2000; m2=1800; mz=3880;g=9.81; r=0.367; CdA=2.77; f=0.013; nT=0.85;ig=[5.56 2.769 1.644 1.00 0.793]; i0=5.83;If=0.218; Iw1=1.798; Iw2=3.598;Iw=2*Iw1+4*Iw2;for i=1:69n(i)=(i+11)*50;Ttq(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)^4; endfor j=1:5for i=1:69Ft(i,j)=Ttq(i)*ig(j)*i0*nT/r;ua(i,j)=0.377*r*n(i)/(ig(j)*i0);Fz(i,j)=CdA*ua(i,j)^2/21.15+mz*g*f;endendplot(ua,Ft,ua,Ff,ua,Ff+Fw)title('汽车驱动力与行驶阻力平衡图');xlabel('ua(km/h)');ylabel('Ft(N)');gtext('Ft1')gtext('Ft2')gtext('Ft3')gtext('Ft4')gtext('Ft5')gtext('Ff+Fw')(2)求最大速度和最大爬坡度for k=1:175n1(k)=3300+k*0.1;Ttq(k)=-19.313+295.27*(n1(k)/1000)-165.44*(n1(k)/1000)^2 +40.874*(n1(k)/1000)^33.8445*(n1(k)/1000)^4;Ft(k)=Ttq(k)*ig(5)*i0*nT/r;ua(k)=0.377*r*n1(k)/(ig(5)*i0);Fz(k)=CdA*ua(k)^2/21.15+mz*g*f;E(k)=abs((Ft(k)-Fz(k)));endfor k=1:175if(E(k)==min(E))disp('汽车最高车速=');disp(ua(k));disp('km/h');endendfor p=1:150n2(p)=2000+p*0.5;Ttq(p)=-19.313+295.27*(n2(p)/1000)-165.44*(n2(p)/1000)^2+40.874*(n2(p)/1000) ^3-3.8445*(n2(p)/1000)^4;Ft(p)=Ttq(p)*ig(1)*i0*nT/r;ua(p)=0.377*r*n2(p)/(ig(1)*i0);Fz(p)=CdA*ua(p)^2/21.15+mz*g*f;af(p)=asin((Ft(p)-Fz(p))/(mz*g));endfor p=1:150if(af(p)==max(af))i=tan(af(p));disp('汽车最大爬坡度=');disp(i);endend汽车最高车速=99.0679km/h汽车最大爬坡度=0.3518（3）计算2档起步加速到70km/h所需时间for i=1:69n(i)=(i+11)*50;Ttq(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)^4; endfor j=1:5for i=1:69deta=1+Iw/(mz*r^2)+If*ig(j)^2*i0^2*nT/(mz*r^2);ua(i,j)=0.377*r*n(i)/(ig(j)*i0);a(i,j)=(Ttq(i)*ig(j)*i0*nT/r-CdA*ua(i,j)^2/21.15-mz*g*f)/(deta*mz);if(a(i,j)<=0)a(i,j)=a(i-1,j);endif(a(i,j)>0.05)b1(i,j)=a(i,j);u1(i,j)=ua(i,j);elseb1(i,j)=a(i-1,j);u1(i,j)=ua(i-1,j);endb(i,j)=1/b1(i,j);endendx1=u1(:,1);y1=b(:,1);x2=u1(:,2);y2=b(:,2);x3=u1(:,3);y3=b(:,3);x4=u1(:,4);y4=b(:,4);x5=u1(:,5);y5=b(:,5);plot(x1,y1,x2,y2,x3,y3,x4,y4,x5,y5); title('加速度倒数时间曲线');axis([0 120 0 30]);xlabel('ua(km/h)');ylabel('1/aj');gtext('1/a1')gtext('1/a2')gtext('1/a3')gtext('1/a4')gtext('1/a5')for i=1:69A=ua(i,3)-ua(69,2);if (A<1&A>0)j=i;endB=ua(i,4)-ua(69,3);if(B<2&B>0)k=i;endif(ua(i,4)<=70)m=i;endendt=ua(1,2)*b(1,2);for p1=2:69t1(p1)=(ua(p1,2)-ua(p1-1,2))*(b(p1,2)+b(p1-1,2))*0.5; t=t+t1(p1);endfor p2=j:69t2(p2)=(ua(p2,3)-ua(p2-1,3))*(b(p2,3)+b(p2-1,3))*0.5;t=t+t2(p2);endfor p3=k:mt3(p3)=(ua(p3,4)-ua(p3-1,4))*(b(p3,4)+b(p3-1,4))*0.5;t=t+t3(p3);endt=t+(ua(j,3)-ua(69,2))*b(69,2)+(ua(k,4)-ua(69,3))*b(69,3)+(70-ua(m,4))*b(m,4);tz=t/3.6;disp('加速时间=');disp(tz);disp('s');加速时间=29.0585s二、计算与绘制题1 中货车的1）汽车功率平衡图；2）最高档与次高档的等速百公里油耗曲线。

一、确定一轻型货车的动力性能。

1）绘制汽车驱动力与行驶阻力平衡图；2）求汽车最高车速与最大爬坡度；3）绘制汽车行驶加速度倒数曲线；用计算机求汽车用Ⅱ档起步加速行驶至 70km/h 所需的加速时间。

已知数据略。

（参见《汽车理论》习题第一章第3题）解题程序如下:用Matlab语言(1)绘制汽车驱动力与行驶阻力平衡图m1=2000; m2=1800; mz=3880;g=9.81; r=0.367; CdA=2.77; f=0.013; nT=0.85;ig=[5.56 2.769 1.644 1.00 0.793]; i0=5.83;If=0.218; Iw1=1.798; Iw2=3.598;Iw=2*Iw1+4*Iw2;for i=1:69n(i)=(i+11)*50;Ttq(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)^4;endfor j=1:5for i=1:69Ft(i,j)=Ttq(i)*ig(j)*i0*nT/r;ua(i,j)=0.377*r*n(i)/(ig(j)*i0);Fz(i,j)=CdA*ua(i,j)^2/21.15+mz*g*f; endendplot(ua,Ft,ua,Ff,ua,Ff+Fw)title('汽车驱动力与行驶阻力平衡图'); xlabel('ua(km/h)');ylabel('Ft(N)');gtext('Ft1')gtext('Ft2')gtext('Ft3')gtext('Ft4')gtext('Ft5')gtext('Ff+Fw')(2)求最大速度和最大爬坡度for k=1:175n1(k)=3300+k*0.1;Ttq(k)=-19.313+295.27*(n1(k)/1000)-165.44*(n1(k)/1000)^2+40.874*(n1(k)/1000)^33.8445*(n1(k)/1000)^4;Ft(k)=Ttq(k)*ig(5)*i0*nT/r;ua(k)=0.377*r*n1(k)/(ig(5)*i0);Fz(k)=CdA*ua(k)^2/21.15+mz*g*f;E(k)=abs((Ft(k)-Fz(k)));endfor k=1:175if(E(k)==min(E))disp('汽车最高车速=');disp(ua(k));disp('km/h');endendfor p=1:150n2(p)=2000+p*0.5;Ttq(p)=-19.313+295.27*(n2(p)/1000)-165.44*(n2(p)/1000)^2+40.874*(n2(p)/1000)^3-3.8445*(n2(p)/1000)^4;Ft(p)=Ttq(p)*ig(1)*i0*nT/r;ua(p)=0.377*r*n2(p)/(ig(1)*i0);Fz(p)=CdA*ua(p)^2/21.15+mz*g*f;af(p)=asin((Ft(p)-Fz(p))/(mz*g));endfor p=1:150if(af(p)==max(af))i=tan(af(p));disp('汽车最大爬坡度=');disp(i);endend汽车最高车速=99.0679km/h汽车最大爬坡度=0.3518（3）计算2档起步加速到70km/h所需时间for i=1:69n(i)=(i+11)*50;Ttq(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)^4;endfor j=1:5for i=1:69deta=1+Iw/(mz*r^2)+If*ig(j)^2*i0^2*nT/(mz*r^2);ua(i,j)=0.377*r*n(i)/(ig(j)*i0);a(i,j)=(Ttq(i)*ig(j)*i0*nT/r-CdA*ua(i,j)^2/21.15 -mz*g*f)/(deta*mz);if(a(i,j)<=0)a(i,j)=a(i-1,j);endif(a(i,j)>0.05)b1(i,j)=a(i,j);u1(i,j)=ua(i,j);elseb1(i,j)=a(i-1,j);u1(i,j)=ua(i-1,j);endb(i,j)=1/b1(i,j);endendx1=u1(:,1);y1=b(:,1);x2=u1(:,2);y2=b(:,2);x3=u1(:,3);y3=b(:,3);x4=u1(:,4);y4=b(:,4);x5=u1(:,5);y5=b(:,5);plot(x1,y1,x2,y2,x3,y3,x4,y4,x5,y5);title('加速度倒数时间曲线'); axis([0 120 0 30]);xlabel('ua(km/h)');ylabel('1/aj');gtext('1/a1')gtext('1/a2')gtext('1/a3')gtext('1/a4')gtext('1/a5')for i=1:69 A=ua(i,3)-ua(69,2); if (A<1&A>0)j=i;endB=ua(i,4)-ua(69,3);if(B<2&B>0)k=i;endif(ua(i,4)<=70)m=i;endendt=ua(1,2)*b(1,2);for p1=2:69t1(p1)=(ua(p1,2)-ua(p1-1,2))*(b(p1,2)+b(p1-1,2))*0.5;t=t+t1(p1);endfor p2=j:69t2(p2)=(ua(p2,3)-ua(p2-1,3))*(b(p2,3)+b(p2-1,3))*0.5;t=t+t2(p2);endfor p3=k:mt3(p3)=(ua(p3,4)-ua(p3-1,4))*(b(p3,4)+b(p3-1,4))*0.5;t=t+t3(p3);endt=t+(ua(j,3)-ua(69,2))*b(69,2)+(ua(k,4)-ua(69,3))*b(69,3)+(70-ua(m,4))*b(m,4);tz=t/3.6;disp('加速时间=');disp(tz);disp('s');加速时间=29.0585s二、计算与绘制题1 中货车的1）汽车功率平衡图；2）最高档与次高档的等速百公里油耗曲线。

1.3 确定一轻型货车的动力性能（货车可装用4挡或5挡变速器，任选 其中的一种进行整车性能计算）： 1）绘制汽车驱动力与行驶阻力平衡图。

2）求汽车最高车速，最大爬坡度及克服该坡度时相应的附着率。

3）绘制汽车行驶加速度倒数曲线，用图解积分法求汽车用2档起步加速行驶至70km/h 的车速－时间曲线，或者用计算机求汽车用2档起步加速行驶至70km/h 的加速时间。

轻型货车的有关数据：汽油发动机使用外特性的Tq-n 曲线的拟合公式为23419.313295.27()165.44()40.874() 3.8445()1000100010001000q n n n n T =-+-+-式中，Tq 为发动机转矩（N•m ）;n 为发动机转速（r/min ）。

发动机的最低转速n min =600r/min,最高转速n max =4000r/min 。

装载质量 2000kg 整车整备质量 1800kg 总质量 3880kg 车轮半径 0.367m传动系机械效率ηt=0.85滚动阻力系数f=0.013空气阻力系数×迎风面积C D A=2.77m2主减速器传动比i0=5.83飞轮转动惯量I f=0.218kg•m2二前轮转动惯量I w1=1.798kg•m2四后轮转动惯量I w2=3.598kg•m2变速器传动比ig(数据如下表)轴距L=3.2m质心至前轴距离（满载）a=1.974m质心高（满载）hg=0.9m解：Matlab程序：(1) 求汽车驱动力与行驶阻力平衡图和汽车最高车速程序：n=[600:10:4000];Tq=-19.313+295.27*(n/1000)-165.44*(n/1000).^2+40.874*(n/1000).^3-3.8445*(n/1000) .^4;m=3880;g=9.8;nmin=600;nmax=4000;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;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;Ft5=Tq*ig(5)*i0*nT/r;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;ua5=0.377*r*n/ig(5)/i0;ua=[0:5:120];Ff=G*f;Fw=CDA*ua.^2/21.15;Fz=Ff+Fw;plot(ua1,Ft1,ua2,Ft2,ua3,Ft3,ua4,Ft4,ua5,Ft5,ua,Fz);title('驱动力-行驶阻力平衡图');xlabel('ua(km/s)');ylabel('Ft(N)');gtext('Ft1'),gtext('Ft2'),gtext('Ft3'),gtext('Ft4'),gtext('Ft5'),gtext('Ff+Fw');zoom on;[x,y]=ginput(1);zoom off;disp('汽车最高车速=');disp(x);disp('km/h');汽车最高车速=99.3006km/h(2)求汽车最大爬坡度程序：n=[600:10:4000];Tq=-19.313+295.27*(n/1000)-165.44*(n/1000).^2+40.874*(n/1000).^3-3.8445*(n/1000) .^4;m=3880;g=9.8;nmin=600;nmax=4000;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;Ft1=Tq*ig(1)*i0*nT/r;ua1=0.377*r*n/ig(1)/i0;Ff=G*f;Fw1=CDA*ua1.^2/21.15;Fz1=Ff+Fw1;Fi1=Ft1-Fz1;Zoom on;imax=100*tan(asin(max(Fi1/G)));disp('汽车最大爬坡度=');disp(imax);disp('%');汽车最大爬坡度=35.2197%(3)求最大爬坡度相应的附着率和求汽车行驶加速度倒数曲线程序：clearn=[600:10:4000];Tq=-19.313+295.27*(n/1000)-165.44*(n/1000).^2+40.874*(n/1000).^3-3.8445*(n/1000) .^4;m=3880;g=9.8;nmin=600;nmax=4000;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;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; Ft5=Tq*ig(5)*i0*nT/r; 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; ua5=0.377*r*n/ig(5)/i0; Fw1=CDA*ua1.^2/21.15; Fw2=CDA*ua2.^2/21.15; Fw3=CDA*ua3.^2/21.15; Fw4=CDA*ua4.^2/21.15; Fw5=CDA*ua5.^2/21.15; Ff=G*f;deta1=1+(Iw1+Iw2)/(m*r^2)+(If*ig(1)^2*i0^2*nT)/(m*r^2); deta2=1+(Iw1+Iw2)/(m*r^2)+(If*ig(2)^2*i0^2*nT)/(m*r^2); deta3=1+(Iw1+Iw2)/(m*r^2)+(If*ig(3)^2*i0^2*nT)/(m*r^2); deta4=1+(Iw1+Iw2)/(m*r^2)+(If*ig(4)^2*i0^2*nT)/(m*r^2); deta5=1+(Iw1+Iw2)/(m*r^2)+(If*ig(5)^2*i0^2*nT)/(m*r^2); a1=(Ft1-Ff-Fw1)/(deta1*m);ad1=1./a1;a2=(Ft2-Ff-Fw2)/(deta2*m);ad2=1./a2;a3=(Ft3-Ff-Fw3)/(deta3*m);ad3=1./a3;a4=(Ft4-Ff-Fw4)/(deta4*m);ad4=1./a4;a5=(Ft5-Ff-Fw5)/(deta5*m);ad5=1./a5;plot(ua1,ad1,ua2,ad2,ua3,ad3,ua4,ad4,ua5,ad5);axis([0 99 0 10]);title('汽车的加速度倒数曲线');xlabel('ua(km/h)');ylabel('1/a');gtext('1/a1');gtext('1/a2');gtext('1/a3');gtext('1/a4');gtext('1/a5'); a=max(a1);af=asin(max(Ft1-Ff-Fw1)/G);C=tan(af)/(a/L+hg*tan(af)/L);disp('假设后轮驱动，最大爬坡度相应的附着率=');disp(C);假设后轮驱动，最大爬坡度相应的附着率=0.4219(4) >>clearnT=0.85;r=0.367;f=0.013;CDA=2.77;i0=5.83;If=0.218;Iw1=1.798;Iw2=3.598;L=3.2;a=1.947;hg=0.9;m=3880;g=9.8;G=m*g; ig=[5.56 2.769 1.644 1.00 0.793];nmin=600;nmax=4000;u1=0.377*r*nmin./ig/i0;u2=0.377*r*nmax./ig/i0;deta=0*ig;for i=1:5deta(i)=1+(Iw1+Iw2)/(m*r^2)+(If*(ig(i))^2*i0^2*nT)/(m*r^2); endua=[6:0.01:99];N=length(ua);n=0;Tq=0;Ft=0;inv_a=0*ua;delta=0*ua; Ff=G*f;Fw=CDA*ua.^2/21.15;for i=1:Nk=i;if ua(i)<=u2(2)n=ua(i)*(ig(2)*i0/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(2)*i0*nT/r;inv_a(i)=(deta(2)*m)/(Ft-Ff-Fw(i));delta(i)=0.01*inv_a(i)/3.6;elseif ua(i)<=u2(3)n=ua(i)*(ig(3)*i0/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(3)*i0*nT/r;inv_a(i)=(deta(3)*m)/(Ft-Ff-Fw(i));delta(i)=0.01*inv_a(i)/3.6;elseif ua(i)<=u2(4)n=ua(i)*(ig(4)*i0/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(4)*i0*nT/r;inv_a(i)=(deta(4)*m)/(Ft-Ff-Fw(i));delta(i)=0.01*inv_a(i)/3.6;elsen=ua(i)*(ig(5)*i0/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(5)*i0*nT/r;inv_a(i)=(deta(5)*m)/(Ft-Ff-Fw(i));delta(i)=0.01*inv_a(i)/3.6;enda=delta(1:k);t(i)=sum(a);endplot(t,ua);axis([0 80 0 100]);title('汽车2档原地起步换挡加速时间曲线');xlabel('时间t（s）');ylabel('速度ua（km/h）');>> ginputans =25.8223 70.073725.7467 70.0737所以汽车2档原地起步换挡加速行驶至70km/h的加速时间约为25.8s2.7已知货车装用汽油发动机的负荷特性与万有特性。

一、确定一轻型货车的动力性能。

1）绘制汽车驱动力与行驶阻力平衡图；2）求汽车最高车速与最大爬坡度；3）绘制汽车行驶加速度倒数曲线；用计算机求汽车用Ⅱ档起步加速行驶至 70km/h 所需的加速时间。

已知数据略。

（参见《汽车理论》习题第一章第3题）解题程序如下:用Matlab语言(1)绘制汽车驱动力与行驶阻力平衡图m1=2000; m2=1800; mz=3880;g=9.81; r=0.367; CdA=2.77; f=0.013; nT=0.85;ig=[5.56 2.769 1.644 1.00 0.793]; i0=5.83;If=0.218; Iw1=1.798; Iw2=3.598;Iw=2*Iw1+4*Iw2;for i=1:69n(i)=(i+11)*50;Ttq(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)^4; endfor j=1:5for i=1:69Ft(i,j)=Ttq(i)*ig(j)*i0*nT/r;ua(i,j)=0.377*r*n(i)/(ig(j)*i0);Fz(i,j)=CdA*ua(i,j)^2/21.15+mz*g*f;endendplot(ua,Ft,ua,Ff,ua,Ff+Fw)title('汽车驱动力与行驶阻力平衡图');xlabel('ua(km/h)');ylabel('Ft(N)');gtext('Ft1')gtext('Ft2')gtext('Ft3')gtext('Ft4')gtext('Ft5')gtext('Ff+Fw')(2)求最大速度和最大爬坡度for k=1:175n1(k)=3300+k*0.1;Ttq(k)=-19.313+295.27*(n1(k)/1000)-165.44*(n1(k)/1000)^2 +40.874*(n1(k)/1000)^33.8445*(n1(k)/1000)^4;Ft(k)=Ttq(k)*ig(5)*i0*nT/r;ua(k)=0.377*r*n1(k)/(ig(5)*i0);Fz(k)=CdA*ua(k)^2/21.15+mz*g*f;E(k)=abs((Ft(k)-Fz(k)));endfor k=1:175if(E(k)==min(E))disp('汽车最高车速=');disp(ua(k));disp('km/h');endendfor p=1:150n2(p)=2000+p*0.5;Ttq(p)=-19.313+295.27*(n2(p)/1000)-165.44*(n2(p)/1000)^2+40.874*(n2(p)/1000) ^3-3.8445*(n2(p)/1000)^4;Ft(p)=Ttq(p)*ig(1)*i0*nT/r;ua(p)=0.377*r*n2(p)/(ig(1)*i0);Fz(p)=CdA*ua(p)^2/21.15+mz*g*f;af(p)=asin((Ft(p)-Fz(p))/(mz*g));endfor p=1:150if(af(p)==max(af))i=tan(af(p));disp('汽车最大爬坡度=');disp(i);endend汽车最高车速=99.0679km/h汽车最大爬坡度=0.3518（3）计算2档起步加速到70km/h所需时间for i=1:69n(i)=(i+11)*50;Ttq(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)^4; endfor j=1:5for i=1:69deta=1+Iw/(mz*r^2)+If*ig(j)^2*i0^2*nT/(mz*r^2);ua(i,j)=0.377*r*n(i)/(ig(j)*i0);a(i,j)=(Ttq(i)*ig(j)*i0*nT/r-CdA*ua(i,j)^2/21.15-mz*g*f)/(deta*mz);if(a(i,j)<=0)a(i,j)=a(i-1,j);endif(a(i,j)>0.05)b1(i,j)=a(i,j);u1(i,j)=ua(i,j);elseb1(i,j)=a(i-1,j);u1(i,j)=ua(i-1,j);endb(i,j)=1/b1(i,j);endendx1=u1(:,1);y1=b(:,1);x2=u1(:,2);y2=b(:,2);x3=u1(:,3);y3=b(:,3);x4=u1(:,4);y4=b(:,4);x5=u1(:,5);y5=b(:,5);plot(x1,y1,x2,y2,x3,y3,x4,y4,x5,y5); title('加速度倒数时间曲线');axis([0 120 0 30]);xlabel('ua(km/h)');ylabel('1/aj');gtext('1/a1')gtext('1/a2')gtext('1/a3')gtext('1/a4')gtext('1/a5')for i=1:69A=ua(i,3)-ua(69,2);if (A<1&A>0)j=i;endB=ua(i,4)-ua(69,3);if(B<2&B>0)k=i;endif(ua(i,4)<=70)m=i;endendt=ua(1,2)*b(1,2);for p1=2:69t1(p1)=(ua(p1,2)-ua(p1-1,2))*(b(p1,2)+b(p1-1,2))*0.5; t=t+t1(p1);endfor p2=j:69t2(p2)=(ua(p2,3)-ua(p2-1,3))*(b(p2,3)+b(p2-1,3))*0.5;t=t+t2(p2);endfor p3=k:mt3(p3)=(ua(p3,4)-ua(p3-1,4))*(b(p3,4)+b(p3-1,4))*0.5;t=t+t3(p3);endt=t+(ua(j,3)-ua(69,2))*b(69,2)+(ua(k,4)-ua(69,3))*b(69,3)+(70-ua(m,4))*b(m,4);tz=t/3.6;disp('加速时间=');disp(tz);disp('s');加速时间=29.0585s二、计算与绘制题1 中货车的1）汽车功率平衡图；2）最高档与次高档的等速百公里油耗曲线。

第四章1)求利用附着系数曲线的程序：m1=4080;hg1=0.845;L1=3.950;a1=2.100;bt1=0.38;m2=9290;hg2=1.170;L2=3.950;a2=2.950;bt2=0.38;%利用附着系数与制动强度的关系曲线z=0:0.01:0.8;y=z;b1=L1-a1;b2=L2-a2;yf1=bt1*L1.*z./(b1+hg1.*z);yf2=bt2*L2.*z./(b2+hg2.*z);yr1=(1-bt1)*L1.*z./(a1-hg1.*z);yr2=(1-bt2)*L2.*z./(a2-hg2.*z);%ECE法规要求曲线yECE2=(z+0.07)./0.85;z1=0.30:0.01:0.80;yECE1=(z1-0.02)./0.74;z2=0.15:0.01:0.30;yECE3=z2+0.08;yECE4=z2-0.08;plot(z,yf1,'y',z,yf2,'g',z,yr1,'b',z,yr2,'c',z,y,'r--',z,yECE2,'k',z1,yECE1,'k',z2,yECE3,'k',z2,yE CE4,'k')axis([0 0.8 0 0.8]);xlabel('制动强度z/g');ylabel('利用附着系数y');title('利用附着系数与制动强度的关系曲线');gtext('yf1(空车)');gtext('yf2（满载）');gtext('yr1（空车）');gtext('yr2（满载）');gtext('y=z');gtext('ECE法规要求界限')以下是利用附着系数曲线和ECE法规要求曲线界限由利用附着系数曲线和ECE法规要求曲线界限曲线可知该车的制动系统满足法规的要求求制动效率曲线的程序：m1=4080;hg1=0.845;L1=3.950;a1=2.100;bt1=0.38;m2=9290;hg2=1.170;L2=3.950;a2=2.950;bt2=0.38;b1=L1-a1;b2=L2-a2;%求制动效率曲线Y=(0:0.01:1); %Y为地面附着系数Ef1=b1./(bt1*L1-Y*hg1)*100; %空车Ef2=b2./(bt2*L2-Y*hg2)*100; %满载Er1=a1./((1-bt1)*L1+Y*hg1)*100;Er2=a2./((1-bt2)*L2+Y*hg2)*100;plot(Y,Ef1,'y',Y,Ef2,'b',Y,Er1,'k',Y,Er2,'r')axis([0 1.0 0 100]);xlabel('附着系数Y');ylabel('制动效率（%）');title('制动效率曲线')gtext('Ef2(满载)'),gtext('Er1（空车）'),gtext('Ef2（满载）');以下是制动效率曲线：2),3)问的计算程序：m1=4080;hg1=0.845;L1=3.950;a1=2.100;bt1=0.38; m2=9290;hg2=1.170;L2=3.950;a2=2.950;bt2=0.38; b1=L1-a1;b2=L2-a2;%求制动效率曲线Y=(0:0.01:1); %Y为地面附着系数Ef1=b1./(bt1*L1-Y*hg1)*100; %空车Ef2=b2./(bt2*L2-Y*hg2)*100; %满载Er1=a1./((1-bt1)*L1+Y*hg1)*100;Er2=a2./((1-bt2)*L2+Y*hg2)*100;%求制动距离t1=0.02;t2=0.2;ua0=30;Y1=0.8;g=9.8;abmax1=Y1*g*Er1(81)/100;abmax2=Y1*g*Er2(81)/100;disp('空载时汽车不抱死的制动距离')s1=1/3.6*(t1+t2/2)*ua0+ua0^2/(25.92*abmax1) disp('满载时汽车不抱死的制动距离')s2=1/3.6*(t1+t2/2)*ua0+ua0^2/(25.92*abmax2)%当汽车制动系后部管路破损时的制动距离Fxb11=Y1*m1*g*b1/(L1-Y1*hg1); %当后轮的制动力为0,空车时前轮的地面制动力Fxb12=Y1*m2*g*b2/(L2-Y1*hg2); %当后轮的制动力为0,满载时前轮的地面制动力a11=Fxb11/m1;a12=Fxb12/m2;disp('当汽车制动系后部管路破损时空车的制动距离')s11=1/3.6*(t1+t2/2)*ua0+ua0^2/(25.92*a11)disp('当汽车制动系后部管路破损时满载的制动距离')s12=1/3.6*(t1+t2/2)*ua0+ua0^2/(25.92*a12)%当汽车制动系前部管路破损时的制动距离Fxb21=Y1*m1*g*a1/(L1+Y1*hg1); %当前轮的制动力为0,空车时后轮的地面制动力Fxb22=Y1*m2*g*a2/(L1+Y1*hg2); %当前轮的制动力为0,满载时后轮的地面制动力a21=Fxb21/m1;a22=Fxb22/m2;disp('当汽车制动系前部管路破损时空车的制动距离')s21=1/3.6*(t1+t2/2)*ua0+ua0^2/(25.92*a21)disp('当汽车制动系前部管路破损时满载的制动距离')s22=1/3.6*(t1+t2/2)*ua0+ua0^2/(25.92*a22)运行结果为：空载时汽车不抱死的制动距离s1 =7.5906满载时汽车不抱死的制动距离s2 =6.0819当汽车制动系后部管路破损时空车的制动距离s11 =8.8379当汽车制动系后部管路破损时满载的制动距离s12 =14.3486当汽车制动系前部管路破损时空车的制动距离s21 =10.7561当汽车制动系前部管路破损时满载的制动距离s22 =8.3354。

一、确定一轻型货车的动力性能。

1）绘制汽车驱动力与行驶阻力平衡图；2）求汽车最高车速与最大爬坡度；3）绘制汽车行驶加速度倒数曲线；用计算机求汽车用Ⅱ档起步加速行驶至 70km/h 所需的加速时间。

已知数据略。

（参见《汽车理论》习题第一章第3题）解题程序如下:用Matlab语言(1)绘制汽车驱动力与行驶阻力平衡图m1=2000; m2=1800; mz=3880;g=9.81; r=0.367; CdA=2.77; f=0.013; nT=0.85; ig=[5.56 2.769 1.644 1.00 0.793]; i0=5.83;If=0.218; Iw1=1.798; Iw2=3.598; Iw=2*Iw1+4*Iw2;for i=1:69n(i)=(i+11)*50;Ttq(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)^4;endfor j=1:5for i=1:69Ft(i,j)=Ttq(i)*ig(j)*i0*nT/r;ua(i,j)=0.377*r*n(i)/(ig(j)*i0);Fz(i,j)=CdA*ua(i,j)^2/21.15+mz*g*f; endendplot(ua,Ft,ua,Ff,ua,Ff+Fw)title('汽车驱动力与行驶阻力平衡图'); xlabel('ua(km/h)');ylabel('Ft(N)');gtext('Ft1')gtext('Ft2')gtext('Ft3')gtext('Ft4')gtext('Ft5')gtext('Ff+Fw')(2)求最大速度和最大爬坡度for k=1:175n1(k)=3300+k*0.1;Ttq(k)=-19.313+295.27*(n1(k)/1000)-165.44*(n1(k)/1000)^2+40.874*(n1(k)/1000)^33.8445*(n1(k)/1000)^4;Ft(k)=Ttq(k)*ig(5)*i0*nT/r;ua(k)=0.377*r*n1(k)/(ig(5)*i0);Fz(k)=CdA*ua(k)^2/21.15+mz*g*f;E(k)=abs((Ft(k)-Fz(k)));endfor k=1:175if(E(k)==min(E))disp('汽车最高车速=');disp(ua(k));disp('km/h');endendfor p=1:150n2(p)=2000+p*0.5;Ttq(p)=-19.313+295.27*(n2(p)/1000)-165.44*(n2(p)/1000)^2+40.874*(n2(p)/1000)^3-3.8445*(n2(p)/1000)^4;Ft(p)=Ttq(p)*ig(1)*i0*nT/r;ua(p)=0.377*r*n2(p)/(ig(1)*i0);Fz(p)=CdA*ua(p)^2/21.15+mz*g*f;af(p)=asin((Ft(p)-Fz(p))/(mz*g));endfor p=1:150if(af(p)==max(af))i=tan(af(p));disp('汽车最大爬坡度=');disp(i);endend汽车最高车速=99.0679km/h汽车最大爬坡度=0.3518（3）计算2档起步加速到70km/h所需时间for i=1:69n(i)=(i+11)*50;Ttq(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)^4;endfor j=1:5for i=1:69deta=1+Iw/(mz*r^2)+If*ig(j)^2*i0^2*nT/(mz*r^2); ua(i,j)=0.377*r*n(i)/(ig(j)*i0);a(i,j)=(Ttq(i)*ig(j)*i0*nT/r-CdA*ua(i,j)^2/21.15-mz*g*f)/(deta*mz);if(a(i,j)<=0)a(i,j)=a(i-1,j);endif(a(i,j)>0.05)b1(i,j)=a(i,j);u1(i,j)=ua(i,j);elseb1(i,j)=a(i-1,j);u1(i,j)=ua(i-1,j);endb(i,j)=1/b1(i,j);endendx1=u1(:,1);y1=b(:,1);x2=u1(:,2);y2=b(:,2);x3=u1(:,3);y3=b(:,3);x4=u1(:,4);y4=b(:,4);x5=u1(:,5);y5=b(:,5);plot(x1,y1,x2,y2,x3,y3,x4,y4,x5,y5); title('加速度倒数时间曲线');axis([0 120 0 30]);xlabel('ua(km/h)');ylabel('1/aj');gtext('1/a1')gtext('1/a2')gtext('1/a3')gtext('1/a4')gtext('1/a5')for i=1:69A=ua(i,3)-ua(69,2);if (A<1&A>0)j=i;endB=ua(i,4)-ua(69,3);if(B<2&B>0)k=i;endif(ua(i,4)<=70)m=i;endendt=ua(1,2)*b(1,2);for p1=2:69t1(p1)=(ua(p1,2)-ua(p1-1,2))*(b(p1,2)+b(p1-1,2))*0.5;t=t+t1(p1);endfor p2=j:69t2(p2)=(ua(p2,3)-ua(p2-1,3))*(b(p2,3)+b(p2-1,3))*0.5;t=t+t2(p2);endfor p3=k:mt3(p3)=(ua(p3,4)-ua(p3-1,4))*(b(p3,4)+b(p3-1,4))*0.5;t=t+t3(p3);endt=t+(ua(j,3)-ua(69,2))*b(69,2)+(ua(k,4)-ua(69,3))*b(69,3)+(70-ua(m,4))*b(m,4);tz=t/3.6;disp('加速时间=');disp(tz);disp('s');加速时间=29.0585s二、计算与绘制题1 中货车的1）汽车功率平衡图；2）最高档与次高档的等速百公里油耗曲线。

确定一轻型货车的动力性能（货车可装用4挡或5挡变速器，任选其中的一种进行整车性能计算）：1）绘制汽车驱动力与行驶阻力平衡图。

2）求汽车最高车速，最大爬坡度及克服该坡度时相应的附着率。

3）绘制汽车行驶加速度倒数曲线，用图解积分法求汽车用2档起步加速行驶至70km/h 的车速－时间曲线，或者用计算机求汽车用2档起步加速行驶至70km/h的加速时间。

轻型货车的有关数据：汽油发动机使用外特性的Tq-n曲线的拟合公式为式中，Tq为发动机转矩（N?m）;n为发动机转速（r/min）。

发动机的最低转速nmin =600r/min,最高转速nmax=4000r/min。

装载质量 2000kg整车整备质量 1800kg总质量 3880kg车轮半径 0.367m传动系机械效率ηt=0.85滚动阻力系数f=0.013空气阻力系数×迎风面积C D A=2.77m2主减速器传动比i0=5.83飞轮转动惯量 I f=0.218kg?m2二前轮转动惯量I w1=1.798kg?m2四后轮转动惯量I w2=3.598kg?m2变速器传动比 ig(数据如下表)轴距 L=3.2m质心至前轴距离（满载） a=1.974m质心高（满载） hg=0.9m解：Matlab程序：(1) 求汽车驱动力与行驶阻力平衡图和汽车最高车速程序：n=[600:10:4000];Tq=-19.313+295.27*(n/1000)-165.44*(n/1000).^2+40.874*(n/1000).^3-3.8445*(n/100 0).^4;m=3880;g=9.8;nmin=600;nmax=4000;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;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;Ft5=Tq*ig(5)*i0*nT/r;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;ua5=0.377*r*n/ig(5)/i0;ua=[0:5:120];Ff=G*f;Fw=CDA*ua.^2/21.15;Fz=Ff+Fw;plot(ua1,Ft1,ua2,Ft2,ua3,Ft3,ua4,Ft4,ua5,Ft5,ua,Fz);title('驱动力-行驶阻力平衡图');xlabel('ua(km/s)');ylabel('Ft(N)');gtext('Ft1'),gtext('Ft2'),gtext('Ft3'),gtext('Ft4'),gtext('Ft5'),gtext('Ff+Fw' );zoom on;[x,y]=ginput(1);zoom off;disp('汽车最高车速=');disp(x);disp('km/h');汽车最高车速=99.3006km/h(2)求汽车最大爬坡度程序：n=[600:10:4000];Tq=-19.313+295.27*(n/1000)-165.44*(n/1000).^2+40.874*(n/1000).^3-3.8445*(n/1000).^4;m=3880;g=9.8;nmin=600;nmax=4000;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;Ft1=Tq*ig(1)*i0*nT/r;ua1=0.377*r*n/ig(1)/i0;Ff=G*f;Fw1=CDA*ua1.^2/21.15;Fz1=Ff+Fw1;Fi1=Ft1-Fz1;Zoom on;imax=100*tan(asin(max(Fi1/G)));disp('汽车最大爬坡度=');disp(imax);disp('%');汽车最大爬坡度=35.2197%(3)求最大爬坡度相应的附着率和求汽车行驶加速度倒数曲线程序：clearn=[600:10:4000];Tq=-19.313+295.27*(n/1000)-165.44*(n/1000).^2+40.874*(n/1000).^3-3.8445*(n/100 0).^4;m=3880;g=9.8;nmin=600;nmax=4000;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;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;Ft5=Tq*ig(5)*i0*nT/r;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;ua5=0.377*r*n/ig(5)/i0;Fw1=CDA*ua1.^2/21.15;Fw2=CDA*ua2.^2/21.15;Fw3=CDA*ua3.^2/21.15;Fw4=CDA*ua4.^2/21.15;Fw5=CDA*ua5.^2/21.15;Ff=G*f;deta1=1+(Iw1+Iw2)/(m*r^2)+(If*ig(1)^2*i0^2*nT)/(m*r^2); deta2=1+(Iw1+Iw2)/(m*r^2)+(If*ig(2)^2*i0^2*nT)/(m*r^2); deta3=1+(Iw1+Iw2)/(m*r^2)+(If*ig(3)^2*i0^2*nT)/(m*r^2); deta4=1+(Iw1+Iw2)/(m*r^2)+(If*ig(4)^2*i0^2*nT)/(m*r^2); deta5=1+(Iw1+Iw2)/(m*r^2)+(If*ig(5)^2*i0^2*nT)/(m*r^2); a1=(Ft1-Ff-Fw1)/(deta1*m);ad1=1./a1;a2=(Ft2-Ff-Fw2)/(deta2*m);ad2=1./a2;a3=(Ft3-Ff-Fw3)/(deta3*m);ad3=1./a3;a4=(Ft4-Ff-Fw4)/(deta4*m);ad4=1./a4;a5=(Ft5-Ff-Fw5)/(deta5*m);ad5=1./a5;plot(ua1,ad1,ua2,ad2,ua3,ad3,ua4,ad4,ua5,ad5);axis([0 99 0 10]);title('汽车的加速度倒数曲线');xlabel('ua(km/h)');ylabel('1/a');gtext('1/a1');gtext('1/a2');gtext('1/a3');gtext('1/a4');gtext('1/a5'); a=max(a1);af=asin(max(Ft1-Ff-Fw1)/G);C=tan(af)/(a/L+hg*tan(af)/L);disp('假设后轮驱动，最大爬坡度相应的附着率=');disp(C);假设后轮驱动，最大爬坡度相应的附着率=0.4219(4) >>clearnT=0.85;r=0.367;f=0.013;CDA=2.77;i0=5.83;If=0.218;Iw1=1.798;Iw2=3.598;L=3.2;a=1.947;hg=0.9;m=3880;g=9.8; G=m*g; ig=[5.56 2.769 1.644 1.00 0.793];nmin=600;nmax=4000;u1=0.377*r*nmin./ig/i0;u2=0.377*r*nmax./ig/i0;deta=0*ig;for i=1:5deta(i)=1+(Iw1+Iw2)/(m*r^2)+(If*(ig(i))^2*i0^2*nT)/(m*r^2);endua=[6:0.01:99];N=length(ua);n=0;Tq=0;Ft=0;inv_a=0*ua;delta=0*ua;Ff=G*f;Fw=CDA*ua.^2/21.15;for i=1:Nk=i;if ua(i)<=u2(2)n=ua(i)*(ig(2)*i0/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(2)*i0*nT/r;inv_a(i)=(deta(2)*m)/(Ft-Ff-Fw(i));delta(i)=0.01*inv_a(i)/3.6;elseif ua(i)<=u2(3)n=ua(i)*(ig(3)*i0/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(3)*i0*nT/r;inv_a(i)=(deta(3)*m)/(Ft-Ff-Fw(i));delta(i)=0.01*inv_a(i)/3.6;elseif ua(i)<=u2(4)n=ua(i)*(ig(4)*i0/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(4)*i0*nT/r;inv_a(i)=(deta(4)*m)/(Ft-Ff-Fw(i));delta(i)=0.01*inv_a(i)/3.6;elsen=ua(i)*(ig(5)*i0/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(5)*i0*nT/r;inv_a(i)=(deta(5)*m)/(Ft-Ff-Fw(i)); delta(i)=0.01*inv_a(i)/3.6;enda=delta(1:k);t(i)=sum(a);endplot(t,ua);axis([0 80 0 100]);title('汽车2档原地起步换挡加速时间曲线'); xlabel('时间t（s）');ylabel('速度ua（km/h）');>> ginputans =25.8223 70.073725.7467 70.0737所以汽车2档原地起步换挡加速行驶至70km/h 的加速时间约为25.8s2.7已知货车装用汽油发动机的负荷特性与万有特性。

一、确定一轻型货车的动力性能。

欧阳家百（2021.03.07）1）绘制汽车驱动力与行驶阻力平衡图；2）求汽车最高车速与最大爬坡度；3）绘制汽车行驶加速度倒数曲线；用计算机求汽车用Ⅱ档起步加速行驶至 70km/h 所需的加速时间。

已知数据略。

（参见《汽车理论》习题第一章第3题）解题程序如下:用Matlab语言(1)绘制汽车驱动力与行驶阻力平衡图m1=2000; m2=1800; mz=3880;g=9.81; r=0.367; CdA=2.77; f=0.013; nT=0.85;ig=[5.56 2.769 1.644 1.00 0.793]; i0=5.83;If=0.218; Iw1=1.798; Iw2=3.598;Iw=2*Iw1+4*Iw2;for i=1:69n(i)=(i+11)*50;Ttq(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)^4; endfor j=1:5for i=1:69Ft(i,j)=Ttq(i)*ig(j)*i0*nT/r;ua(i,j)=0.377*r*n(i)/(ig(j)*i0);Fz(i,j)=CdA*ua(i,j)^2/21.15+mz*g*f;endendplot(ua,Ft,ua,Ff,ua,Ff+Fw)title('汽车驱动力与行驶阻力平衡图');xlabel('ua(km/h)');ylabel('Ft(N)');gtext('Ft1')gtext('Ft2')gtext('Ft3')gtext('Ft4')gtext('Ft5')gtext('Ff+Fw')(2)求最大速度和最大爬坡度for k=1:175n1(k)=3300+k*0.1;Ttq(k)=-19.313+295.27*(n1(k)/1000)-165.44*(n1(k)/1000)^2 +40.874*(n1(k)/1000)^33.8445*(n1(k)/1000)^4;Ft(k)=Ttq(k)*ig(5)*i0*nT/r;Fz(k)=CdA*ua(k)^2/21.15+mz*g*f;E(k)=abs((Ft(k)-Fz(k)));endfor k=1:175if(E(k)==min(E))disp('汽车最高车速=');disp(ua(k));disp('km/h');endendfor p=1:150n2(p)=2000+p*0.5;Ttq(p)=-19.313+295.27*(n2(p)/1000)-165.44*(n2(p)/1000)^2+40.874*(n2(p)/1000) ^3-3.8445*(n2(p)/1000)^4;Ft(p)=Ttq(p)*ig(1)*i0*nT/r;ua(p)=0.377*r*n2(p)/(ig(1)*i0);Fz(p)=CdA*ua(p)^2/21.15+mz*g*f;af(p)=asin((Ft(p)-Fz(p))/(mz*g));endfor p=1:150if(af(p)==max(af))disp('汽车最大爬坡度=');disp(i);endend汽车最高车速=99.0679km/h汽车最大爬坡度=0.3518（3）计算2档起步加速到70km/h所需时间for i=1:69n(i)=(i+11)*50;Ttq(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)^4; endfor j=1:5for i=1:69deta=1+Iw/(mz*r^2)+If*ig(j)^2*i0^2*nT/(mz*r^2);ua(i,j)=0.377*r*n(i)/(ig(j)*i0);a(i,j)=(Ttq(i)*ig(j)*i0*nT/r-CdA*ua(i,j)^2/21.15-mz*g*f)/(deta*mz);if(a(i,j)<=0)a(i,j)=a(i-1,j);endif(a(i,j)>0.05)u1(i,j)=ua(i,j);elseb1(i,j)=a(i-1,j);u1(i,j)=ua(i-1,j);endb(i,j)=1/b1(i,j);endendx1=u1(:,1);y1=b(:,1);x2=u1(:,2);y2=b(:,2);x3=u1(:,3);y3=b(:,3);x4=u1(:,4);y4=b(:,4);x5=u1(:,5);y5=b(:,5);plot(x1,y1,x2,y2,x3,y3,x4,y4,x5,y5); title('加速度倒数时间曲线');axis([0 120 0 30]);xlabel('ua(km/h)');ylabel('1/aj');gtext('1/a1')gtext('1/a2')gtext('1/a3')gtext('1/a4')for i=1:69A=ua(i,3)-ua(69,2);if (A<1&A>0)j=i;endB=ua(i,4)-ua(69,3);if(B<2&B>0)k=i;endif(ua(i,4)<=70)m=i;endendt=ua(1,2)*b(1,2);for p1=2:69t1(p1)=(ua(p1,2)-ua(p1-1,2))*(b(p1,2)+b(p1-1,2))*0.5; t=t+t1(p1);endfor p2=j:69t2(p2)=(ua(p2,3)-ua(p2-1,3))*(b(p2,3)+b(p2-1,3))*0.5; t=t+t2(p2);endt3(p3)=(ua(p3,4)-ua(p3-1,4))*(b(p3,4)+b(p3-1,4))*0.5;t=t+t3(p3);endt=t+(ua(j,3)-ua(69,2))*b(69,2)+(ua(k,4)-ua(69,3))*b(69,3)+(70-ua(m,4))*b(m,4);tz=t/3.6;disp('加速时间=');disp(tz);disp('s');加速时间=29.0585s二、计算与绘制题1 中货车的1）汽车功率平衡图；2）最高档与次高档的等速百公里油耗曲线。

1.3n=600:1:4000; r=0.367; i0=5.83; eff=0.85; f=0.013;m=3880; g=9.8; G=m*g; CdA=2.77; a=1.947; hg=0.9; L=3.2;Iw1=1.798; Iw2=3.598; Iw=Iw1+Iw2; If=0.218;Ttq=-19.313+295.27*n/1000-165.44*(n/1000).^2+40.874*(n/1000).^3-3.8445*(n/1 000).^4;%驱动力行驶阻力平衡图for ig=[5.56,2.769,1.644,1.00,0.793]Ua=0.377*r*n/ig/i0;Ft=Ttq*ig*i0*eff/r;plot(Ua,Ft);hold on;endFf=G*f;ua=0:0.1:max(Ua);Fw=CdA*ua.^2/21.15;plot(ua,(Ff+Fw)); title('驱动力-行驶阻力平衡图'); xlabel('Ua/(km/h)');ylabel('Ft/N'); gtext('Ft1'),gtext('Ft2'),gtext('Ft3'),gtext('Ft4'),gtext('Ft5'),gtext('Ff+Fw')[x,y]=ginput(1); disp('汽车的最高车速');disp(x);disp('km/h');%最大爬坡度及最大爬坡度时的附着率Ua=0.377*r*n/5.56/i0;Ft=Ttq*5.56*i0*eff/r;Fw=CdA*Ua.^2/21.15;i=tan(asin((Ft-(Ff+Fw))/G));disp('汽车的最大爬坡度');disp(max(i));C=max(i)/(a/L+hg/L*max(i));disp('克服最大爬坡度时的附着率');disp(C);%加速度倒数曲线figure;for ig=[5.56,2.769,1.644,1.00,0.793]Ua=0.377*r*n/ig/i0;q=1+Iw/(m*r^2)+If*ig^2*i0^2*eff/(m*r^2);Ft=Ttq*ig*i0*eff/r;Fw=CdA*Ua.^2/21.15;as=(Ft-(Ff+Fw))/q/m;plot(Ua,1./as);hold on;endaxis([0 98 0 10]);title('行驶加速度倒数曲线');xlabel('Ua/(km/h)');ylabel('1/a'); gtext('1/a1'),gtext('1/a2'),gtext('1/a3'),gtext('1/a4'),gtext('1/a5'); %加速时间曲线u(1)=0.377*r*600/i0/2.769;dt=0.01;w=1;t(1)=0;ig=2.769; while(u(w)<99.08)n(w)=u(w)*ig*i0/0.377/r;Ttq(w)=-19.313+295.27*n(w)/1000-165.44*(n(w)/1000)^2+40.874*(n(w)/1000)^3-3.8445*(n(w)/1000)^4;Ft(w)=Ttq(w)*ig*i0*eff/r;Ff=G*f;Fw(w)=CdA*u(w)^2/21.15;q=1+Iw/(m*r^2)+If*ig^2*i0^2*eff/(m*r^2);a(w)=3.6*(Ft(w)-(Ff+Fw(w)))/q/m;u(w+1)=u(w)+a(w)*dt;if(u(w+1)>=0.377*4000*r/2.769/i0)ig=1.644;endif(u(w+1)>=0.377*4000*r/1.644/i0)ig=1.00;endif(u(w+1)>=0.377*4000*r/1.00/i0)ig=0.793;endt(w+1)=(w+1)*dt;w=w+1;endfigure;plot(t,u);axis([0 60 0 100]);title('2挡原地起步加速时间曲线');xlabel('时间t/s'),ylabel('车速u/(km/h)');[x1,y1]=ginput(1);disp('加速到70km/h 的时间');disp(x1);0204060801001202000400060008000100001200014000驱动力-行驶阻力平衡图Ua/(km/h)F t /N102030405060708090012345678910行驶加速度倒数曲线Ua/(km/h)1/a10203040506001020304050607080901002挡原地起步加速时间曲线时间t/s车速u /(k m /h)1.8Iw1=2.25; Iw2=2.25; Iw=Iw1+Iw2; If=0.25; m=1600; g=9.8;G=m*g; Ttqmax=140; i1=3.85; i0=4.08; eff=0.9; r=0.3; hg=0.63; b=1.25; L=2.7; q=1+Iw/(m*r^2)+If*i1^2*i0^2*eff/(m*r^2); Ft=Ttqmax*i1*i0*eff/r; a=Ft/q/m; q=a/g;C1=q/(b/L-hg/L*q); if(C1>0.6)disp('发动机转矩不能充分发挥'); elsedisp('发动机转矩能够充分发挥'); endb=(q/0.6+hg/L*q)*L;disp('调整后的b值');disp(b);disp('调整后的前轴负荷率'),disp(b/L);1.9Iw=3.6; If=0.22; m=2152; g=9.8; r=0.367; eff=0.9; i4=1; i0=4.55;amax=0.75; Ua=50/3.6; CdA=1.5;q=1+Iw/(m*r^2);f=q*0.59/3.6/g;disp('汽车在该路面上的滚动阻力系数');disp(f);q=1+Iw/(m*r^2)+If*i4^2*i0^2*eff/(m*r^2);D4max=f+q*amax/g;disp('最大动力因数');disp(D4max);Fw=CdA*Ua^2/21.15;D1max=(D4max*G+Fw)*i1/i4/G;imax=tan(asin((D1max-f*sqrt(1-D1max^2+f^2))/(1+f^2)));disp('最大爬坡度'),disp(imax);2.7n=600:1:4000; r=0.367; i0=5.83; eff=0.85; f=0.013;CdA=2.77;m=3880; g=9.8;G=m*g;Ttq=-19.313+295.27*n/1000-165.44*(n/1000).^2+40.874*(n/1000).^3-3.8445*(n/1 000).^4;for ig=[5.56,2.769,1.644,1.00,0.793]Ua=0.377*r*n/ig/i0;Pe=Ttq.*n/9550;plot(Ua,Pe);hold on;endUa=0:0.1:max(Ua);Pf=G*f*Ua/3600;Pw=CdA*Ua.^3/76140;plot(Ua,(Pf+Pw)/eff);title('汽车的功率平衡图'),xlabel('Ua/(km/h)'),ylabel('P/kw');%等速百公里燃油消耗n1=[815,1207,1614,2012,2603,3006,3403,3804];b0=[1326.8,1354.7,1284.4,1122.9,1141.0,1051.2,1233.9,1129.7];b1=[-416.46,-303.98,-189.75,-121.59,-98.893,-73.714,-84.478,-45.291] ;b2=[72.379,36.657,14.524,7.0035,4.4763,2.8593,2.9788,0.71113];b3=[-5.8629,-2.0553,-0.51184,-0.18517,-0.091077,-0.05138,-0.047449,-0.00075215 ];b4=[0.17768,0.043072,0.0068164,0.0018555,0.00068906,0.00035032,0.00028230,-0 .000038568];B0=spline(n1,b0,n); B1=spline(n1,b1,n); B2=spline(n1,b2,n); B3=spline(n1,b3,n);B4=spline(n1,b4,n);deng=7;figure;for ig=[1.00,0.793]Ua=0.377*r*n/ig/i0;Pf=G*f*Ua/3600;Pw=CdA*Ua.^3/76140;P=(Pf+Pw)/eff;b=B0+B1.*P+B2.*P.^2+B3.*P.^3+B4.*P.^4;Q=P.*b./(1.02*Ua*deng);plot(Ua,Q);hold on;endaxis([0 100 12 28]);title('最高挡与次高挡等速百公里油耗曲线'),xlabel('Ua/(km/h)'),ylabel('百公里油耗Qs/(L/100km)');204060801001200102030405060708090100汽车的功率平衡图Ua/(km/h)P /k w020406080100121416182022242628最高挡与次高挡等速百公里油耗曲线Ua/(km/h)百公里油耗Q s /(L /100k m )4.3beta=0.38; L=3.95; a1=2.1; b1=L-a1; hg1=0.845; a2=2.95; b2=L-a2; hg2=1.17;g=9.8; z=0:0.01:1;faif1=beta*z./(1/L*(b1+z*hg1));fair1=(1-beta)*z./(1/L*(a1-z*hg1));faif2=beta*z./(1/L*(b2+z*hg2));fair2=(1-beta)*z./(1/L*(a2-z*hg2));plot(z,faif1,'r',z,fair1,'g',z,faif2,'b',z,fair2,'k');fai=0:0.01:1;Ef1=(b1/L)./(beta-fai*hg1/L);Er1=(a1/L)./((1-beta)+fai*hg1/L);Ef2=(b2/L)./(beta-fai*hg2/L);Er2=(a2/L)./((1-beta)+fai*hg2/L);figure;plot(fai,Ef1,'r',fai,Er1,'g',fai,Ef2,'b',fai,Er2,'k'); axis([0 1 0 1]);fai=0.8;Er1=(a1/L)/((1-beta)+fai*hg1/L);Er2=(a2/L)/((1-beta)+fai*hg2/L);abmax1=fai*Er1*g;abmax2=fai*Er2*g;t21=0.02; t22=0.2; u0=30;s1=1/3.6*(t21+t22/2)*u0+u0^2/25.92/abmax1; s2=1/3.6*(t21+t22/2)*u0+u0^2/25.92/abmax2; disp('空载时的制动距离'),disp(s1);disp('满载时的制动距离'),disp(s2);%前部管路损坏时制动距离z1=a1*fai/(L+fai*hg1); z2=a2*fai/(L+fai*hg2);abmax1=z1*g; abmax2=z2*g;s1=1/3.6*(t21+t22/2)*u0+u0^2/25.92/abmax1;s2=1/3.6*(t21+t22/2)*u0+u0^2/25.92/abmax2;disp('前部管路损坏时空载制动距离');disp(s1);disp('前部管路损坏时满载制动距离');disp(s2);%后部管路损坏时的制动距离z1=b1*fai/(L-fai*hg1);z2=b2*fai/(L-fai*hg2);abmax1=z1*g; abmax2=z2*g;s1=1/3.6*(t21+t22/2)*u0+u0^2/25.92/abmax1;s2=1/3.6*(t21+t22/2)*u0+u0^2/25.92/abmax2;disp('后部管路损坏时空载制动距离');disp(s1);disp('后部管路损坏时满载制动距离');disp(s2);4.5hg=0.63; b=1.25; L=2.7; beta=0.65; fai=0.7; g=9.8;fai0=(L*beta-b)/hg;if(fai<fai0)disp('前轮先抱死,制动效率为'); E=(b/L)/(beta-fai*hg/L); elsedisp('后轮先抱死,制动效率为'); E=(a/L)/((1-beta)+fai*hg/L);disp('最大制动减速度'),disp(E*fai*g);disp('a)、b)、c)的双回路制动系统制动系增益都为G');disp('1回路失效时，a)、b)、c)的制动系增益分别为0.35,0.5,0.5');disp('1回路失效时，a)、b)、c)的制动系增益分别为0.65,0.5,0.5');disp('a)中1回路失效时最大制动强度');zmax1=a*fai/(L+fai*hg)disp('a)中1回路失效时制动效率');disp(zmax1/fai)disp('a)中1回路失效时最大制动减速度');abmax1=zmax1*gdisp('a)中2回路失效时最大制动强度');zmax2=a*fai/(L+fai*hg)disp('a)中1回路失效时制动效率');disp(zmax1/fai)disp('a)中2回路失效时最大制动减速度');abmax2=zmax2*gdisp('b)或c)中1或2回路失效时最大制动强度');z=fai*b/(2*L*beta-fai*hg)disp('b)或c)中1或2回路失效时最大制动减速度');abmax=z*gdisp('b)或c)中1或2回路失效时制动效率');disp(z/fai)disp('双回路系统a制动系增益最大，一个回路失效时的最大制动减速度也比b、c大，所以其性能较优')disp('b和c制动系增益相同,两者在一个回路失效时的制动效率相同。

汽车理论图形MATLAB程序功率平衡图m=1230;g=9.8;ig=[3.615 2.053 1.393 1.031 0.837]; i0=3.75;r=0.31;yt=0.9;f=0.017;CD=0.31;A=2.2;np=6000;Pemax=83;%绘制汽车驱动力与行驶阻力平衡图for i=1:56;n=500:100:6000;Pe(i)=Pemax*(n(i)/np+(n(i)/np)^2-(n(i)/np)^3); Tq(i)=9549*Pe(i)/n(i);endfor j=1:5for i=1:56Ft(i,j)=Tq(i)*ig(j)*i0*yt/r;ua(i,j)=0.377*r*n(i)/(ig(j)*i0);Fz(i,j)=m*g*f+CD*A*(ua(i,j)^2)/21.15;endendfigureplot(ua,Ft,ua,Fz);title('汽车驱动力与行驶阻力平衡图');xlabel('ua(km/h)');ylabel('Ft(N)');text(20,6700,'Ft1');text(40,4000,'Ft2');text(50,2800,'Ft3');text(80,2000,'Ft4');text(100,1600, 'Ft5');text(100,800,'Ff+Fw');for k=1:56;n=500:100:6000;Pe(k)=Pemax*(n(k)/np+(n(k)/np)^2-(n(k)/np)^3); Tq(k)=9549*Pe(k)/n(k);Ft(k)=T q(k)*ig(4)*i0*yt/r;ua(k)=0.377*r*n(k)/(ig(4)*i0);Fz(k)=m*g*f+CD*A*(ua(k)^2)/21.15;E(k)=abs((Ft(k)-Fz(k)));end[Emin,kmin]=min(E);Umax=ua(kmin)加速度曲线图m=1230;g=9.8;ig=[3.615 2.053 1.393 1.031 0.837]; i0=3.75;r=0.31;yt=0.9;f=0.017;CD=0.31;A=2.2;np=6000;Pemax=83;deta=[1.33 1.12 1.07 1.05 1.04];for i=1:56;n=500:100:6000;Pe(i)=Pemax*(n(i)/np+(n(i)/np)^2-(n(i)/np)^3); Tq(i)=9549*Pe(i)/n(i);endfor j=1:5for i=1:56Ft(i,j)=Tq(i)*ig(j)*i0*yt/r;ua(i,j)=0.377*r*n(i)/(ig(j)*i0);Fz(i,j)=m*g*f+CD*A*(ua(i,j)^2)/21.15;a(i,j)=(Ft(i,j)-Fz(i,j))/(deta(j)*m);b(i,j)= 1./a(i,j);endendx1=ua(:,1);y1=b(:,1);x2=ua(:,2);y2=b(:,2);x3=ua(:,3);y3=b(:,3);x4=ua(:,4);y4=b(:,4);x5=ua(:,5);y5=b(:,5);figureplot(x1,y1,x2,y2,x3,y3,x4,y4,x5,y5);axis([0 185 0 15]);title('汽车行驶加速度倒数曲线');xlabel('ua(km/h)');ylabel('1/a');汽车二挡原地起步加速时间nT=0.9;r=0.31;f=0.0177;CD=0.31;A=2.2;;i0=3.75;m=3880;g=9.8;Pemax=83;np=6000;G=m*g; ig=[3.615 2.053 1.393 1.031 0.837];nmin=600;nmax=6000;u1=0.377*r*nmin./ig/i0;u2=0.377*r*nmax./ig/i0;deta=[1.33 1.12 1.07 1.05 1.04];ua=[1:0.01:180];N=length(ua);n=0;T q=0;Ft=0;inv_a=0*ua;del ta=0*ua; Ff=G*f;Fw=CD*A*ua.^2/21.15;for i=1:Nk=i;if ua(i)<=u2(2)n=ua(i)*(ig(2)*i0/r)/0.377;Tq=9549*(Pemax*(n/np+(n/np)^2-(n/np)^3))/n;Ft=Tq*ig(2)*i0*nT/r;inv_a(i)=(deta(2)*m)/(Ft-Ff-Fw(i));delta(i)=0.01*inv_a(i)/3.6;elseif ua(i)<=u2(3)n=ua(i)*(ig(3)*i0/r)/0.377;Tq=9549*(Pemax*(n/np+(n/np)^2-(n/np)^3))/n;Ft=Tq*ig(3)*i0*nT/r;inv_a(i)=(deta(3)*m)/(Ft-Ff-Fw(i));delta(i)=0.01*inv_a(i)/3.6;elseif ua(i)<=u2(4)n=ua(i)*(ig(4)*i0/r)/0.377;Tq=9549*(Pemax*(n/np+(n/np)^2-(n/np)^3))/n;Ft=Tq*ig(4)*i0*nT/r;inv_a(i)=(deta(4)*m)/(Ft-Ff-Fw(i));delta(i)=0.01*inv_a(i)/3.6;elsen=ua(i)*(ig(5)*i0/r)/0.377;Tq=9549*(Pemax*(n/np+(n/np)^2-(n/np)^3))/n;Ft=Tq*ig(5)*i0*nT/r;inv_a(i)=(deta(5)*m)/(Ft-Ff-Fw(i));delta(i)=0.01*inv_a(i)/3.6;enda=delta(1:k);t(i)=sum(a);endplot(t,ua);axis([0 80 0 100]);title('汽车2档原地起步换挡加速时间曲线'); xlabel('时间t（s）'); ylabel('速度ua（km/h）');功率平衡图m=1230;g=9.8;ig=[3.615 2.053 1.393 1.031 0.837]; i0=3.75;r=0.31;yt=0.9;f=0.017;CD=0.31;A=2.2;np=6000;Pemax=83;deta=[1.33 1.12 1.07 1.05 1.04];for j=1:5for i=1:56;n=500:100:6000;Pe(i)=Pemax*(n(i)/np+(n(i)/np)^2-(n(i)/np)^3);Tq(i)=9549*Pe(i)/n(i);ua(i,j)=0.377*r*n(i)/(ig(j)*i0);Pz(i,j)=(m*g*f*ua(i,j)/3600+CD*A*ua(i,j)^3/76140)/yt; endendplot(ua,Pe,ua,Pz);title('功率平衡图');xlabel('ua(km/h)');ylabel('P(kW)');text(40,90,'一档Pe');text(80,90,'二档Pe');text(110,90,'三档Pe');text(150,90,'四档Pe');text(200,90,'五档Pe');text(100,25,'Pz');%绘制最高档和次高档的等速百公里油耗曲线n0=[815,1207,1614,2012,2603,3006,3403,3804];for j=1:5for i=1:8Pd(i)=Pemax*(n0(i)/np+(n0(i)/np)^2-(n0(i)/np)^3); Td(i)=9549*Pd(i)/n0(i);u(i,j)=0.377*r*n0(i)/(ig(j)*i0);endendb(1)=1326.8-416.46*Pd(1)+72.379*Pd(1)^2-5.8629*Pd(1)^3+0.17768*Pd(1)^4;b(2)=1354.7-303.98*Pd(2)+36.657*Pd(2)^2-2.0553*Pd(2)^3+0.043072*Pd(2)^4;b(3)=1284.4-189.75*Pd(3)+14.524*Pd(3)^2-0.51184*Pd(3)^3+0.0068164*Pd(3)^4;b(4)=1122.9-121.59*Pd(4)+7.0035*Pd(4)^2-0.18517*Pd(4)^3+0.0018555*Pd(4)^4;b(5)=1141.0-98.893*Pd(5)+4.4763*Pd(5)^2-0.091077*Pd(5)^3+0.00068906*Pd(5)^4;b(6)=1051.2-73.714*Pd(6)+2.8593*Pd(6)^2-0.05138*Pd(6)^3+0.00035032*Pd(6)^4;b(7)=1233.9-84.478*Pd(7)+2.9788*Pd(7)^2-0.047449*Pd(7)^3+0.00028230*Pd(7)^4;b(8)=1129.7-45.291*Pd(8)+0.71113*Pd(8)^2+0.00075215*Pd(8)^3-0.000038568*Pd(8)^4; u1=u(:,1)';u2=u(:,2)';u3=u(:,3)';u4=u(:,4)';u5=u(:,5)';B1=polyfit(u1,b,3);B2=polyfit(u2,b,3);B3=polyfit(u3,b,3);B4=polyfit(u4,b,3);B5=polyfit(u5,b,3);for k=1:56bh(k,1)=polyval(B1,ua(k,1));bh(k,2)=polyval(B2,ua(k,2));bh(k,3)=polyval(B3,ua(k,3));bh(k,4)=polyval(B4,ua(k,4));bh(k,5)=polyval(B5,ua(k,5));endfor i=1:5for k=1:56Q(k,i)=Pz(k,i)*bh(k,i)/(1.02*ua(k,i)*7.10);endendplot(ua(:,4),Q(:,4),ua(:,5),Q(:,5));axis([0 185 0 20]);title('最高档（五档）和次高档（四档）等速百公里油耗图'); xlabel('ua(km/h)');ylabel('Qs(L/100km)');text(90,10,'四档');text(125,10,'五档');爬坡度图m=1230;g=9.8;G=m*g;ig=[3.615 2.053 1.393 1.031 0.837]; i0=3.75;r=0.31;yt=0.9;f=0.017;CD=0.31;A=2.2;np=6000;Pemax=83;for i=1:56;n=500:100:6000;Pe(i)=Pemax*(n(i)/np+(n(i)/np)^2-(n(i)/np)^3);Tq(i)=9549*Pe(i)/n(i);endfor j=1:5for i=1:56Ft(i,j)=Tq(i)*ig(j)*i0*yt/r;ua(i,j)=0.377*r*n(i)/(ig(j)*i0);Fz(i,j)=m*g*f+CD*A*(ua(i,j)^2)/21.15;F=Ft-Fz;I=tan(asin(Ft/G))*100;endendplot(ua,I);hold on;title('汽车的爬坡度图');xlabel('ua(km/h)');ylabel('i(%)');text(50,55,'一档');text(50,35,'二档');text(100,22,'三档');text(150,15,'四档');text(200,13,'五档');动力因数图m=1230;g=9.8;G=m*g;ig=[3.615 2.053 1.393 1.031 0.837]; i0=3.75;r=0.31;yt=0.9;f=0.017;CD=0.31;A=2.2;np=6000;Pemax=83;%绘制汽车驱动力与行驶阻力平衡图for i=1:56;n=500:100:6000;Pe(i)=Pemax*(n(i)/np+(n(i)/np)^2-(n(i)/np)^3); Tq(i)=9549*Pe(i)/n(i);endfor j=1:5for i=1:56Ft(i,j)=Tq(i)*ig(j)*i0*yt/r;ua(i,j)=0.377*r*n(i)/(ig(j)*i0); Fw(i,j)=CD*A*(ua(i,j)^2)/21.15; F=Ft-Fw;D=F/G;endendplot(ua,D);hold on;axis([0 190 0 0.6]);title('汽车的动力特性图'); xlabel('ua(km/h)');ylabel('动力因数)');text(40,0.5,'一档');text(60,0.3,'二档');text(100,0.2,'三档');text(140,0.1,'四档');text(140,0.04,'五档');。

汽车理论编程作业1.2.3章汽车理论作业：第⼀章1.3选四档变速器，⽤MATLAB语⾔驱动⼒与⾏驶阻⼒平衡图m1=2000;m2=1800;mz=3880;g=9.81;f=0.013;n=600:1:4000;nt=0.85;r=0.367;i0=5.83;ig1=6.09;ig2=3.09;ig3=1.71;ig4=1.00;ua1=0.377*r.*n/(ig1.*i0);ua2=0.377*r.*n/(ig2.*i0);ua3=0.377*r.*n/(ig3.*i0);ua4=0.377*r.*n/(ig4.*i0);tq=-19.313+295.27*(n/1000)-165.44*(n/1000).^2+40.874*(n/1000).^3-3.8445*(n/1000).^4; ft1=tq.*ig1.*i0.*nt/r; ft2=tq.*ig2.*i0.*nt/r;ft3=tq.*ig3.*i0.*nt/r;ft4=tq.*ig4.*i0.*nt/r;fz1=mz.*g.*f+2.77*ua1.^2/21.15; %fz=Ff+Fwfz2=mz.*g.*f+2.77*ua2.^2/21.15;fz3=mz.*g.*f+2.77*ua3.^2/21.15;fz4=mz.*g.*f+2.77*ua4.^2/21.15;plot(ua1,ft1,ua2,ft2,ua3,ft3,ua4,ft4,ua1,fz1,ua2,fz2,ua3,fz3,ua4,fz4);title('驱动⼒与⾏驶阻⼒平衡图');Xlabel('ua(km/h)');Ylabel('ft(N)');m1=2000;m2=1800;mz=3880;g=9.81;f=0.013;k=600:1:4000;n(k)=k;nt=0.85;r=0.367;i0=5.83;ig1=6.09;ig2=3.09;ig3=1.71;ig4=1.00;ua1(k)=0.377*r.*n(k)/(ig1.*i0);ua2(k)=0.377*r.*n(k)/(ig2.*i0);ua3(k)=0.377*r.*n(k)/(ig3.*i0);ua4(k)=0.377*r.*n(k)/(ig4.*i0);tq(k)=-19.313+295.27*(n(k)/1000)-165.44*(n(k)/1000).^2+40.874*(n(k)/1000).^3-3.8445*(n(k)/10 00).^4; ft1(k)=tq(k).*ig1.*i0.*nt/r;ft2(k)=tq(k).*ig2.*i0.*nt/r;ft3(k)=tq(k).*ig3.*i0.*nt/r;ft4(k)=tq(k).*ig4.*i0.*nt/r;fz1(k)=mz.*g.*f+2.77*ua1(k).^2/21.15; %fz=Ff+Fwfz2(k)=mz.*g.*f+2.77*ua2(k).^2/21.15;fz3(k)=mz.*g.*f+2.77*ua3(k).^2/21.15;fz4(k)=mz.*g.*f+2.77*ua4(k).^2/21.15;ua4=max(ua4(k))disp('汽车的最⾼车速=');disp(ua4);disp('km/h');得到汽车的最⾼车速=94.9290(km/h)最⼤坡度和相应的附着率k=600:1:4000;f=0.013;l=3.2;a=1.947;n(k)=knt=0.85;r=0.367;f=0.013;i0=5.83;m=3880;g=9.81;G=m.*g;CDA=2.77;If=0.218;Iw1=1.798;ig1=6.09;ua1(k)=0.377*r.*n(k)/(ig1.*i0);tq(k)=-19.313+295.27*(n(k)/1000)-165.44*(n(k)/1000).^2+40.874*(n(k)/1000).^3-3.8445*(n(k)/10 00).^4; b1=1+(Iw1+Iw2)./(m.*r.^2)+(If.*ig1.^2.*i0.^2.*nt)/(m.*r.^2);ft1(k)=tq(k).*ig1.*i0.*nt/r;fw1(k)=CDA.*(ua1(k).^2)/21.15;D1(k)=(ft1(k)-fw1(k))./G;i(k)=D1(k)-fi=max(i(k));q=i.*l./a;disp('汽车的最⼤爬坡度=');disp(i);disp('最⼤爬坡度相应的附着率=');disp(q);得计算结果：汽车的最⼤爬坡度=0.3648最⼤爬坡度相应的附着率=0.5995加速度倒数曲线n=600:1:4000;nt=0.85;r=0.367;f=0.013;i0=5.83;m=3880;g=9.81;G=m.*g;CDA=2.77;If=0.218;Iw1=1.798;Iw2=3.598;ig1=6.09;ig2=3.09;ig3=1.71;ig4=1.00;ua1=0.377*r.*n/(ig1.*i0);ua2=0.377*r.*n/(ig2.*i0);ua3=0.377*r.*n/(ig3.*i0);ua4=0.377*r.*n/(ig4.*i0);tq=-19.313+295.27*(n/1000)-165.44*(n/1000).^2+40.874*(n/1000).^3-3.8445*(n/1000).^4;b1=1+(Iw1+Iw2)./(m.*r.^2)+(If.*ig1.^2.*i0.^2.*nt)/(m.*r.^2); b2=1+(Iw1+Iw2)./(m.*r.^2)+(If.*ig2.^2.*i0.^2.*nt)/(m.*r.^2); b3=1+ (Iw1+Iw2)./(m.*r.^2)+(If.*ig3.^2.*i0.^2.*nt)/(m.*r.^2); b4=1+(Iw1+Iw2)./(m.*r.^2)+(If.*ig4.^2.*i0.^2.*nt)/(m.*r.^2);ft1=tq.*ig1.*i0.*nt/r;ft2=tq.*ig2.*i0.*nt/r;ft3=tq.*ig3.*i0.*nt/r;ft4=tq.*ig4.*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)./G;D2=(ft2-fw2)./G;D3=(ft3-fw3)./G;D4=(ft4-fw4)./G;a1=g.*(D1-f)/b1;a2=g.*(D2-f)/b2;a3=g.*(D3-f)/b3;a4=g.*(D4-f)/b4;plot(ua1,1./a1,ua2,1./a2,ua3,1./a3,ua4,1./a4); title('加速度倒数曲线图');Xlabel('ua(km/h)');Ylabel('1/a(m/s^2)');加速时间k=600:1:4000;n(k)=k;nt=0.85;r=0.367;f=0.013;i0=5.83;m=3880;g=9.81;G=m.*g;CDA=2.77;If=0.218;Iw1=1.798;Iw2=3.598;ig2=3.09;ig3=1.71;ig4=1.00;ua2(k)=0.377*r.*n(k)/(ig2.*i0);ua3(k)=0.377*r.*n(k)/(ig3.*i0);ua4(k)=0.377*r.*n(k)/(ig4.*i0);tq(k)=-19.313+295.27*(n(k)/1000)-165.44*(n(k)/1000).^2+40.874*(n(k)/1000).^3-3.8445*(n(k)/10 00).^4; b2=1+(Iw1+Iw2)./(m.*r.^2)+(If.*ig2.^2.*i0.^2.*nt)/(m.*r.^2);b3=1+(Iw1+Iw2)./(m.*r.^2)+(If.*ig3.^2.*i0.^2.*nt)/(m.*r.^2);b4=1+(Iw1+Iw2)./(m.*r.^2)+(If.*ig4.^2.*i0.^2.*nt)/(m.*r.^2);ft2(k)=tq(k).*ig2.*i0.*nt/r;ft3(k)=tq(k).*ig3.*i0.*nt/r;ft4(k)=tq(k).*ig4.*i0.*nt/r;fw2(k)=CDA.*(ua2(k).^2)/21.15;fw3(k)=CDA.*(ua3(k).^2)/21.15;fw4(k)=CDA.*(ua4(k).^2)/21.15;D2(k)=(ft2(k)-fw2(k))./G;D3(k)=(ft3(k)-fw3(k))./G;D4(k)=(ft4(k)-fw4(k))./G;a2(k)=g.*(D2(k)-f)/b2;a3(k)=g.*(D3(k)-f)/b3;a4(k)=g.*(D4(k)-f)/b4;t2=trapz(ua2(k),a2(k));t3=trapz(ua3(k),a3(k));t4=trapz(ua4(k),a4(k));tz=(t2+t3+t4)/3.6;disp('加速时间为');disp(tz);得加速时间为：27.4156 s第⼆章2.7题的程序:m=3880;g=9.8;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];nd=400;Qid=0.299;nn=[815 1207 1614 2012 2603 3006 3403 3804];for i=1:69n(i)=(i+11)*50;Tq(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 ).^4;endfor j=1:4for i=1:69ua(i,j)=0.377.*r.*n(i)/(ig(j).*i0);Pe(i,j)=Tq(i).*ig(j).*i0.*nt.*ua(i,j)/(3600.*r);Pfw(i,j)=(m.*g.*f.*ua(i,j)/3600+CdA.*ua(i,j).^3/76140)/nt;endendplot(ua,Pe,ua,Pfw)title('功率平衡图');xlabel('ua(km/h)');ylabel('Pe,Pfw(kw)');功率平衡图如图：最⾼档与次⾼档的等速百公⾥油耗曲线m=3880;g=9.8;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];nd=400;Qid=0.299;nn=[815 1207 1614 2012 2603 3006 3403 3804];for j=1:4for i=1:8Tq1(i)=-19.313+295.27*(nn(i)/1000)-165.44*(nn(i)/1000).^2+40.874*(nn(i)/1000).^3-3.8445*(nn(i )/1000).^4; ua1(i,j)=0.377*nn(i).*r./(ig(j).*i0);Pe1(i,j)=Tq(i).*ig(j).*i0.*ua1(i,j)/(3600.*r);Pfw(i,j)=(m.*g.*f.*ua1(i,j)/3600+CdA.*ua1(i,j).^3/76140)/nt;endendb(1)=0.17768*Pe1(1)^4-5.8629*Pe1(1)^3+72.379*Pe1(1)^2-416.46*Pe1(1)+1326.8;b(2)=0.043072*Pe1(2)^4-2.0553*Pe1(2)^3+36.657*Pe1(2)^2-303.98*Pe1(2)+1354.7;b(3)=0.0068164*Pe1(3)^4-0.51184*Pe1(3)^3+14.524*Pe1(3)^2-189.75*Pe1(3)+1284.4;b(4)=0.0018555*Pe1(4)^4-0.18517*Pe1(4)^3+7.0035*Pe1(4)^2-121.59*Pe1(4)+1122.9;b(5)=0.00068906*Pe1(5)^4-0.091077*Pe1(5)^3+4.4763*Pe1(5)^2-98.893*Pe1(5)+1141.0;b(6)=0.00035032*Pe1(6)^4-0.05138*Pe1(6)^3+2.8593*Pe1(6)^2-73.714*Pe1(6)+1051.2;b(7)=0.00028230*Pe1(7)^4-0.047449*Pe1(7)^3+2.9788*Pe1(7)^2-84.478*Pe1(7)+1233.9;b(8)=-0.000038568*Pe1(8)^4-0.00075215*Pe1(8)^3+0.71113*Pe1(8)^2-45.291*Pe1(8)+1129.7;v3=ua1(:,3)';v4=ua1(:,4)';for s=1:8Qs3(s)=Pfw(s,3)/0.85.*b(s)/(1.02*v3(s)*7);%次⾼挡，%取密度和g的乘积为7.0kg*m/(L*s^2)Qs4(s)=Pfw(s,4)/0.85.*b(s)/(1.02*v4(s)*7);%最⾼挡endfigureplot(v3,Qs3,'-','markersize',14);hold onplot(v4,Qs4,'-','markersize',14);hold offtitle('等速百公⾥油耗曲线');xlabel('ua(km/h)');ylabel('Qs(L/100km)');四档三档第三章m=3880;g=9.8;r=0.367;nt=0.85;f=0.013;CdA=2.77;If=0.218;Iw1=1.798;Iw2=3.598;ig=[6.09 3.09 1.71 1];L=3.2;a=1.947;hg=0.9;i0=[5.17 5.43 5.83 6.17 6.33];%选取最⾼挡，转速n=3403r/min,Pe=60kw，对应的油耗⽐较经济B=0.00028230*Pe^4-0.047449*Pe^3+2.9788*Pe^2-84.478*Pe+1233.9;for s=1:5ua0(s)=0.377*r*3403/(ig(4)*i0(s)); %设各个i0值对应的速度在该情况下为ua0Qs(s)=Pe*B/(1.02*ua0(s)*7.0); %求出各i0值的等速百公⾥油耗endfor i=1:69n(i)=(i+11)*50;Tq(i)=-19.313+295.27*(n(i)/1000)-165.44*(n(i)/1000).^2+40.874*(n(i)/1000).^3-3.8445*(n(i)/10 00).^4; endfor s=1:5 %求各个i0值对应的加速⾄最⾼速时间，从1挡起步for j=1:4 %求加速度倒数曲线for i=1:69deta(j)=1+(Iw1+Iw2) /(m.*r.^2)+If.*ig(j).^2.*i0(s).^2.*nt/(m.*r.^2);ua(i,j)=0.377.*r.*n(i)/(ig(j).*i0(s));Ft(i,j)=Tq(i).*ig(j).*i0(s).*nt/r;Fw(i,j)=CdA.*ua(i,j).^2/21.15;a(i,j)=(Ft(i,j)-Fw(i,j)-m.*g.*f)/(deta(j)*m);b(i,j)=1/a(i,j); %b(i,j)为加速度倒数函数endendk=-1;i=1;while(k<0)k=ua(i,2)-ua(69,1);i=i+1;endw=i-1; %w为从1挡换⾄2挡时的转速的⾃变量k=-1;i=1;while (k<0)k=ua(i,3)-ua(69,2);i=i+1;endx=i-1; %x为换⾄3挡时的转速的⾃变量k=-1;i=1;while (k<0)k=ua(i,4)-ua(69,3);i=i+1;y=i-1; %y为换⾄4挡时的转速的⾃变量t(s)=ua(1,1)*b(1,1); %1挡600r／min前的加速时间for i1=2:69 %1挡加速时间t1(i1)=0.5*(ua(i1,1)-ua(i1-1,1))*(b(i1,1)+b(i1-1,1)); t(s)=t(s)+t1(i1);endt(s)=t(s)+(ua(w,2)-ua(69,1))*b(w,2);for i2=w:69 %2挡加速时间t2(i2)=0.5*(ua(i2,2)-ua(i2-1,2))*(b(i2,2)+b(i2-1,2)); t(s)=t(s)+t2(i2);endt(s)=t(s)+(ua(x,3)-ua(69,2))*b(x,3);for i3=x:69 %3挡加速时间t3(i3)=0.5*(ua(i3,3)-ua(i3-1,3))*(b(i3,3)+b(i3-1,3));t(s)=t(s)+t3(i3);endt(s)=t(s)+(ua(y,4)-ua(69,3))*b(y,4);for i4=y:69 %4挡加速⾄最⾼速时间t4(i4)=0.5*(ua(i4,4)-ua(i4-1,4))*(b(i4,4)+b(i4-1,4));t(s)=t(s)+t4(i4);endt(s)=t(s)/3.6; %把时间单位从(km·s^2)/(m·h)转为send %对应上⾯的“for s=1:5”disp('各i0值对应的加速时间');disp(t);plot(Qs,t,'-')title('燃油经济性⼀加速时间曲线');xlabel('Qs(L)');ylabel('t(s)');%从曲线图可以看出，i0值越⼤，汽车加速性能越好，但燃油经济性越差。

1.3 确定一轻型货车的动力性能（货车可装用4挡或5挡变速器，任选 其中的一种进行整车性能计算）：1）绘制汽车驱动力与行驶阻力平衡图。

2）求汽车最高车速，最大爬坡度及克服该坡度时相应的附着率。

3）绘制汽车行驶加速度倒数曲线，用图解积分法求汽车用2档起步加速行驶至70km/h 的车速－时间曲线，或者用计算机求汽车用2档起步加速行驶至70km/h 的加速时间。

轻型货车的有关数据：汽油发动机使用外特性的Tq -n 曲线的拟合公式为23419.313295.27()165.44()40.874() 3.8445()1000100010001000q n n n n T =-+-+- 式中，Tq 为发动机转矩（N•m ）;n 为发动机转速（r/min ）。

发动机的最低转速n min =600r/min,最高转速n max =4000r/min 。

装载质量 2000kg整车整备质量 1800kg总质量 3880kg车轮半径 0.367m传动系机械效率 ηt =0.85滚动阻力系数 f =0.013空气阻力系数×迎风面积 C D A =2.77m 2主减速器传动比 i 0=5.83飞轮转动惯量 I f =0.218kg•m 2二前轮转动惯量 I w1=1.798kg•m 2四后轮转动惯量 I w2=3.598kg•m 2变速器传动比 ig(数据如下表)轴距L=3.2m质心至前轴距离（满载）a=1.974m质心高（满载）hg=0.9m解：Matlab程序：(1) 求汽车驱动力与行驶阻力平衡图和汽车最高车速程序：n=[600:10:4000];Tq=-19.313+295.27*(n/1000)-165.44*(n/1000).^2+40.874*(n/1000).^3-3.8445*(n/10 00).^4;m=3880;g=9.8;nmin=600;nmax=4000;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;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;Ft5=Tq*ig(5)*i0*nT/r;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;ua5=0.377*r*n/ig(5)/i0;ua=[0:5:120];Ff=G*f;Fw=CDA*ua.^2/21.15;Fz=Ff+Fw;plot(ua1,Ft1,ua2,Ft2,ua3,Ft3,ua4,Ft4,ua5,Ft5,ua,Fz);title('驱动力-行驶阻力平衡图');xlabel('ua(km/s)');ylabel('Ft(N)');gtext('Ft1'),gtext('Ft2'),gtext('Ft3'),gtext('Ft4'),gtext('Ft5'),gtext('Ff+Fw'); zoom on;[x,y]=ginput(1);zoom off;disp('汽车最高车速=');disp(x);disp('km/h');汽车最高车速=99.3006km/h(2)求汽车最大爬坡度程序：n=[600:10:4000];Tq=-19.313+295.27*(n/1000)-165.44*(n/1000).^2+40.874*(n/1000).^3-3.8445*(n/10 00).^4;m=3880;g=9.8;nmin=600;nmax=4000;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;Ft1=Tq*ig(1)*i0*nT/r;ua1=0.377*r*n/ig(1)/i0;Ff=G*f;Fw1=CDA*ua1.^2/21.15;Fz1=Ff+Fw1;Fi1=Ft1-Fz1;Zoom on;imax=100*tan(asin(max(Fi1/G)));disp('汽车最大爬坡度=');disp(imax);disp('%');汽车最大爬坡度=35.2197%(3)求最大爬坡度相应的附着率和求汽车行驶加速度倒数曲线程序：clearn=[600:10:4000];Tq=-19.313+295.27*(n/1000)-165.44*(n/1000).^2+40.874*(n/1000).^3-3.8445*(n/10 00).^4;m=3880;g=9.8;nmin=600;nmax=4000;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;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;Ft5=Tq*ig(5)*i0*nT/r;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;ua5=0.377*r*n/ig(5)/i0;Fw1=CDA*ua1.^2/21.15;Fw2=CDA*ua2.^2/21.15;Fw3=CDA*ua3.^2/21.15;Fw4=CDA*ua4.^2/21.15;Fw5=CDA*ua5.^2/21.15;Ff=G*f;deta1=1+(Iw1+Iw2)/(m*r^2)+(If*ig(1)^2*i0^2*nT)/(m*r^2); deta2=1+(Iw1+Iw2)/(m*r^2)+(If*ig(2)^2*i0^2*nT)/(m*r^2); deta3=1+(Iw1+Iw2)/(m*r^2)+(If*ig(3)^2*i0^2*nT)/(m*r^2); deta4=1+(Iw1+Iw2)/(m*r^2)+(If*ig(4)^2*i0^2*nT)/(m*r^2); deta5=1+(Iw1+Iw2)/(m*r^2)+(If*ig(5)^2*i0^2*nT)/(m*r^2); a1=(Ft1-Ff-Fw1)/(deta1*m);ad1=1./a1;a2=(Ft2-Ff-Fw2)/(deta2*m);ad2=1./a2;a3=(Ft3-Ff-Fw3)/(deta3*m);ad3=1./a3;a4=(Ft4-Ff-Fw4)/(deta4*m);ad4=1./a4;a5=(Ft5-Ff-Fw5)/(deta5*m);ad5=1./a5;plot(ua1,ad1,ua2,ad2,ua3,ad3,ua4,ad4,ua5,ad5);axis([0 99 0 10]);title('汽车的加速度倒数曲线');xlabel('ua(km/h)');ylabel('1/a');gtext('1/a1');gtext('1/a2');gtext('1/a3');gtext('1/a4');gtext('1/a5'); a=max(a1);af=asin(max(Ft1-Ff-Fw1)/G);C=tan(af)/(a/L+hg*tan(af)/L);disp('假设后轮驱动，最大爬坡度相应的附着率=');disp(C);假设后轮驱动，最大爬坡度相应的附着率=0.4219(4)>>clearnT=0.85;r=0.367;f=0.013;CDA=2.77;i0=5.83;If=0.218;Iw1=1.798;Iw2=3.598;L=3.2;a=1.947;hg=0.9;m=3880;g=9.8; G=m*g; ig=[5.56 2.769 1.644 1.00 0.793];nmin=600;nmax=4000;u1=0.377*r*nmin./ig/i0;u2=0.377*r*nmax./ig/i0;deta=0*ig;for i=1:5deta(i)=1+(Iw1+Iw2)/(m*r^2)+(If*(ig(i))^2*i0^2*nT)/(m*r^2);endua=[6:0.01:99];N=length(ua);n=0;Tq=0;Ft=0;inv_a=0*ua;delta=0*ua;Ff=G*f;Fw=CDA*ua.^2/21.15;for i=1:Nk=i;if ua(i)<=u2(2)n=ua(i)*(ig(2)*i0/r)/0.377;Tq=-19.313+295.27*(n/1000)-165.44*(n/1000)^2+40.874*(n/1000)^3-3.8445*(n/100 0)^4;Ft=Tq*ig(2)*i0*nT/r;inv_a(i)=(deta(2)*m)/(Ft-Ff-Fw(i));delta(i)=0.01*inv_a(i)/3.6;elseif ua(i)<=u2(3)n=ua(i)*(ig(3)*i0/r)/0.377;Tq=-19.313+295.27*(n/1000)-165.44*(n/1000)^2+40.874*(n/1000)^3-3.8445*(n/100 0)^4;Ft=Tq*ig(3)*i0*nT/r;inv_a(i)=(deta(3)*m)/(Ft-Ff-Fw(i));delta(i)=0.01*inv_a(i)/3.6;elseif ua(i)<=u2(4)n=ua(i)*(ig(4)*i0/r)/0.377;Tq=-19.313+295.27*(n/1000)-165.44*(n/1000)^2+40.874*(n/1000)^3-3.8445*(n/100 0)^4;Ft=Tq*ig(4)*i0*nT/r;inv_a(i)=(deta(4)*m)/(Ft-Ff-Fw(i));delta(i)=0.01*inv_a(i)/3.6;elsen=ua(i)*(ig(5)*i0/r)/0.377;Tq=-19.313+295.27*(n/1000)-165.44*(n/1000)^2+40.874*(n/1000)^3-3.8445*(n/100 0)^4;Ft=Tq*ig(5)*i0*nT/r;inv_a(i)=(deta(5)*m)/(Ft-Ff-Fw(i));delta(i)=0.01*inv_a(i)/3.6;enda=delta(1:k);t(i)=sum(a);endplot(t,ua);axis([0 80 0 100]);title('汽车2档原地起步换挡加速时间曲线');xlabel('时间t（s）');ylabel('速度ua（km/h）');>> ginputans =25.8223 70.073725.7467 70.0737所以汽车2档原地起步换挡加速行驶至70km/h 的加速时间约为25.8s2.7已知货车装用汽油发动机的负荷特性与万有特性。

一、确定一轻型货车的动力性能。

1）绘制汽车驱动力与行驶阻力平衡图；2）求汽车最高车速与最大爬坡度；3）绘制汽车行驶加速度倒数曲线；用计算机求汽车用Ⅱ档起步加速行驶至 70km/h 所需的加速时间。

已知数据略。

（参见《汽车理论》习题第一章第3题）解题程序如下:用Matlab语言(1)绘制汽车驱动力与行驶阻力平衡图m1=2000; m2=1800; mz=3880;g=9.81; r=0.367; CdA=2.77; f=0.013; nT=0.85;ig=[5.56 2.769 1.644 1.00 0.793]; i0=5.83;If=0.218; Iw1=1.798; Iw2=3.598;Iw=2*Iw1+4*Iw2;for i=1:69n(i)=(i+11)*50;Ttq(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)^4;endfor j=1:5for i=1:69Ft(i,j)=Ttq(i)*ig(j)*i0*nT/r;ua(i,j)=0.377*r*n(i)/(ig(j)*i0);Fz(i,j)=CdA*ua(i,j)^2/21.15+mz*g*f; endendplot(ua,Ft,ua,Ff,ua,Ff+Fw)title('汽车驱动力与行驶阻力平衡图'); xlabel('ua(km/h)');ylabel('Ft(N)');gtext('Ft1')gtext('Ft2')gtext('Ft3')gtext('Ft4')gtext('Ft5')gtext('Ff+Fw')(2)求最大速度和最大爬坡度for k=1:175n1(k)=3300+k*0.1;Ttq(k)=-19.313+295.27*(n1(k)/1000)-165.44*(n1(k)/1000)^2+40.874*(n1(k)/1000)^33.8445*(n1(k)/1000)^4;Ft(k)=Ttq(k)*ig(5)*i0*nT/r;ua(k)=0.377*r*n1(k)/(ig(5)*i0);Fz(k)=CdA*ua(k)^2/21.15+mz*g*f;E(k)=abs((Ft(k)-Fz(k)));endfor k=1:175if(E(k)==min(E))disp('汽车最高车速=');disp(ua(k));disp('km/h');endendfor p=1:150n2(p)=2000+p*0.5;Ttq(p)=-19.313+295.27*(n2(p)/1000)-165.44*(n2(p)/1000)^2+40.874*(n2(p)/1000)^3-3.8445*(n2(p)/1000)^4;Ft(p)=Ttq(p)*ig(1)*i0*nT/r;ua(p)=0.377*r*n2(p)/(ig(1)*i0);Fz(p)=CdA*ua(p)^2/21.15+mz*g*f;af(p)=asin((Ft(p)-Fz(p))/(mz*g));endfor p=1:150if(af(p)==max(af))i=tan(af(p));disp('汽车最大爬坡度=');disp(i);endend汽车最高车速=99.0679km/h汽车最大爬坡度=0.3518（3）计算2档起步加速到70km/h所需时间for i=1:69n(i)=(i+11)*50;Ttq(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)^4;endfor j=1:5for i=1:69deta=1+Iw/(mz*r^2)+If*ig(j)^2*i0^2*nT/(mz*r^2); ua(i,j)=0.377*r*n(i)/(ig(j)*i0);a(i,j)=(Ttq(i)*ig(j)*i0*nT/r-CdA*ua(i,j)^2/21.15-mz*g*f)/(deta*mz);if(a(i,j)<=0)a(i,j)=a(i-1,j);endif(a(i,j)>0.05)b1(i,j)=a(i,j);u1(i,j)=ua(i,j);elseb1(i,j)=a(i-1,j);u1(i,j)=ua(i-1,j);endb(i,j)=1/b1(i,j);endendx1=u1(:,1);y1=b(:,1);x2=u1(:,2);y2=b(:,2);x3=u1(:,3);y3=b(:,3);x4=u1(:,4);y4=b(:,4);x5=u1(:,5);y5=b(:,5);plot(x1,y1,x2,y2,x3,y3,x4,y4,x5,y5); title('加速度倒数时间曲线'); axis([0 120 0 30]);xlabel('ua(km/h)');ylabel('1/aj');gtext('1/a1')gtext('1/a2')gtext('1/a3')gtext('1/a4')gtext('1/a5')for i=1:69A=ua(i,3)-ua(69,2);if (A<1&A>0)j=i;endB=ua(i,4)-ua(69,3);if(B<2&B>0)k=i;endif(ua(i,4)<=70)m=i;endendt=ua(1,2)*b(1,2);for p1=2:69t1(p1)=(ua(p1,2)-ua(p1-1,2))*(b(p1,2)+b(p1-1,2))*0.5; t=t+t1(p1);endfor p2=j:69t2(p2)=(ua(p2,3)-ua(p2-1,3))*(b(p2,3)+b(p2-1,3))*0.5;t=t+t2(p2);endfor p3=k:mt3(p3)=(ua(p3,4)-ua(p3-1,4))*(b(p3,4)+b(p3-1,4))*0.5; t=t+t3(p3);endt=t+(ua(j,3)-ua(69,2))*b(69,2)+(ua(k,4)-ua(69,3))*b(69,3) +(70-ua(m,4))*b(m,4);tz=t/3.6;disp('加速时间=');disp(tz);disp('s');加速时间=29.0585s二、计算与绘制题1 中货车的1）汽车功率平衡图；2）最高档与次高档的等速百公里油耗曲线。