汽车理论课后习题2.7

第二次作业车辆工程八班胡文贵2013424032解：汽车功率平衡图程序>>clearall>>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=[5.562.7691.6441.0000.793];k=1:5;>>ngk=[600600600600600];>>ngm=[40004000400040004000];>>r=0.367;I0=5.83;eta=0.85;>>ugk=0.377*r*ngk(k)./(Ig(k).*I0);>>ukm=0.377.*r.*ngm(k)./(Ig(k).*I0);>>pz=F.*u1./3600;>>fork=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)holdon,gridonend2)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=[5.562.7691.6441.000.793];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=[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);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);>>fori=1:1:3401b4(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(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([01001030]);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;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=[5.562.7691.6441.0000.793];>>fori=1:5n=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=5.8570e+03tq=-276.9876P=-169.8763n=2.9169e+03tq=170.4435P=52.0596n=1.7318e+03tq=173.5743P=31.4764n=1.0534e+03tq=151.1890P=16.6770n=835.3613tq=133.8503P=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)/(eta*3600)pe=4.7897所以时速25km/h时可以使用五档行驶此时，n=835.3613tq=133.8503P=11.7082利用插值法n=835;k=(835-815)/(1207-835);>>B1=[1326.8-416.4672.379-5.86290.17768];B2=[1354.7-303.9836.657-2.05530.043072];>>fori=1:5x(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(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+03tq=165.1160P=23.1089n=1337;k=(n-1207)/(1614-n);>>B2=[1354.7-303.9836.657-2.05530.043072];B3=[1284.4-189.7514.524-0.511840.0068164];>>fori=1:5x(i)=(k*B3(i)+B2(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+03tq=172.8685P=30.2424>>n=1671;k=(n-1614)/(2012-n);>>B4=[122.9-121.597.0035-0.185170.0018555];>>fori=1:5x(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;2.769;1.644;1.00;0.793];G=38800;Ff=G*f;ua=40;>>fori=1:5th(i)=1+(Iw1+Iw2)/(m*r^2)+(I*i0^2+(ig(i)^2*eta))/(m*r^2);end>>fori=1:5pe=(Ff*ua+CdA*ua.^3/21.15+th(i)*m**ua0.25)/(3600*eta)endpe=22.9607pe=22.4813pe=22.3789pe=22.3438pe=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=5.83;Ig=1.644;>>fori=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;2.769;1.644;1.00;0.793];>>forj=1:16n(j)=ua(j)*ig(3)*i0/(0.377*r)end>>fori=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=[1141.0-98.8934.4763-0.0910770.00068906];B6=[1051.2-73.7142.8593-0.051380.00035032];B4=[1122.9-121.597.0035-0.185170.0018555];B3=[1284.4-189.7514.524-0.511840.0068164];>>fori=1:16ifn(i)<2012k(i)=(n(i)-1614)/(2012-n(i))endend>>fori=1:16ifn(i)<012k(i)=(n(i)-1614)/(2012-n(i))forj=1:5x(j)=(k(i)*B4(j)+B3(j))/(k(i)+1)endb(i)=x(1)+x(2)*pe(i)+x(3)*pe(i).^2+x(4)*pe(i).^3+x(5)*pe(i).^4elseifn(i)>2603k(i)=(n(i)-2603)/(3006-n(i))forj=1:5x(j)=(k(i)*B6(j)+B5(j))/(k(i)+1)endb(i)=x(1)+x(2)*pe(i)+x(3)*pe(i).^2+x(4)*pe(i).^3+x(5)*pe(i).^4elsek(i)=(n(i)-2012)/(2603-n(i))forj=1:5x(j)=(k(i)*B5(j)+B4(j))/(k(i)+1)endb(i)=x(1)+x(2)*pe(i)+x(3)*pe(i).^2+x(4)*pe(i).^3+x(5)*pe(i).^4endend>>pg=6.96;>>fori=1:16Qt(i)=pe(i)*b(i)/(367.1*pg)end;>>delteT=1/(3.6*0.25);>>fori=1:15Qr(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;ig=[5.56;2.769;1.644;1.00;0.793];G=38800;Ff=G*f;ua=50;Cd=2.77;>>fori=1:5th(i)=1+(Iw1+Iw2)/(m*r^2)+(I*i0^2+(ig(i)^2*eta))/(m*r^2);end>>fori=1:5pe=(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];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];forj=1:11n(j)=ua(j)*ig(4)*i0/(0.377*r)end>>fori=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=[1141.0-98.8934.4763-0.0910770.00068906];B4=[1122.9-121.597.0035-0.185170.0018555];B3=[1284.4-189.7514.524-0.511840.0068164];>>fori=1:11ifn(i)<2012k(i)=(n(i)-1614)/(2012-n(i))k(i)=(n(i)-1614)/(2012-n(i))