汽车运用工程大作业

汽车运用工程大作业 １ 汽车动力性计算（加速性能、最高车速、动力因素－加速时间和加速距离） 已知：发动机外特性、装载质量、整备质量、总质量、车轮半径、传动系效率、滚动阻力系数、空气阻力系数×迎风面积、主减速器速比飞轮转动惯量、两个前轮转动惯量、四个后轮转动惯量、变速器速比、轴距、质心至前轴距离、质心高度。 例如，已知数据如下表: 项目 单位 数值 装载质量 kg 1995 整备质量 kg 1700 总质量 kg 3695 车轮半径 m 0.37 传动系效率 0.87 滚动阻力系数 0.012 空气阻力系数×迎风面积 m2 2.60 主减速器速比 5.83 飞轮转动惯量 kgm2 0.22 两前轮转动惯量 kgm2 1.80 四后轮转动惯量 kgm2 3.60 轴距 m 3.40 质心至前轴距离 m 2.0 质心高度 m 0.9 变速器速比 变速器 I档 II档 III档 IV档 V档 四档 6.12 3.11 1.69 1.00 五档 3.55 2.77 1.65 1.00 0.83 发动机外特性 Tq=a+a1(n/c)+a2(n/c)2+a2(n/c)3+a3(n/c)4 参数 a a1 a2 a2 a3 c 数值 -19.31 296 -165 40.9 -3.85 1000 1) 绘制汽车驱动力与行驶阻力平衡图； 2) 求汽车的最高车速、最大爬坡度； 3) 绘制加速度倒数曲线 4) 用图解法或编程绘制汽车动力因数特性曲线 5) 图解手工绘制II档起步，加速至70km/h的车速－时间曲线以及距离－时间曲线。 1、绘制汽车驱动利于行驶阻力平衡图 m1=1995;m2=1700;mz=3695; g=9.81; f=0.0125-0.0025; nt=0.87+0.025; cda=2.60; r=0.37; n=600:1:4600; i0=5.83; ig1=6.12;ig2=3.11;ig3=1.69;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); a=-19.31;a1=296;a2=-165;a3=40.9;a4=-3.85; c=1000; tq=a+a1*(n/c)+a2*(n/c).^2+a3*(n/c).^3+a4*(n/c).^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+cda*ua1.^2/21.15; %fz=Ff+Fw fz2=mz.*g.*f+cda*ua2.^2/21.15; fz3=mz.*g.*f+cda*ua3.^2/21.15; fz4=mz.*g.*f+cda*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)'); gtext('Ft1') gtext('Ft2') gtext('Ft3') gtext('Ft4') gtext('Ff+Fw') 2、求汽车的最高车速、最大爬坡度 1）汽车的最高车速 当Ft=Ff+Fw时,汽车处于稳定状态,并达到最高车速 用matlab对驱动力与行驶阻力图进行放大处理可得交点坐标为（106.53，1757.68） 因此，uamax=106.53km/h 2）最大爬坡度 一档时有最大爬坡度, 用matlab对驱动力与行驶阻力图进行放大处理可得 当ua=8.56km/h时，Ft1-(Ff+Fw)最大值。 m1=1995;m2=1700;mz=3695; g=9.81; f=0.0125-0.0025; nt=0.87+0.025; cda=2.60; r=0.37; i0=5.83; ig1=6.12;ig2=3.11;ig3=1.69;ig4=1.00; ua1=8.56; n=ua1.*ig1.*i0/(0.377.*r); a=-19.31;a1=296;a2=-165;a3=40.9;a4=-3.85; c=1000; tq=a+a1*(n/c)+a2*(n/c).^2+a3*(n/c).^3+a4*(n/c).^4; ft1=tq.*ig1.*i0.*nt/r fz1=mz.*g.*f+cda*ua1.^2/21.15 %fz=Ff+Fw 输出：ft1 =15415N fz1 =371.4871N i=tanα=tan[arcsin(ft1-fz1)/(mz.*g)] 可知： α=24.02°. i=tanα=0.44 3、绘制加速度倒数曲线 n=600:1:4000; r=0.37; nt=0.87+0.025; f=0.0125-0.0025; m=3695;g=9.81;G=m.*g; CDA=2.60; If=0.22;Iw1=1.80;Iw2=3.60; i0=5.83; ig1=6.12;ig2=3.11;ig3=1.69;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); a=-19.31;a1=296;a2=-165;a3=40.9;a4=-3.85; c=1000; tq=a+a1*(n/c)+a2*(n/c).^2+a3*(n/c).^3+a4*(n/c).^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)'); gtext('1/a1') gtext('1/a2') gtext('1/a3') gtext('1/a4') 4、用图解法或编程绘制汽车动力因数特性曲线 n=600:1:4000; r=0.37;nt=0.87+0.025;f=0.0125-0.0025; m=3695;g=9.81;G=m.*g;CDA=2.60; If=0.22;Iw1=1.80;Iw2=3.60; i0=5.83;ig1=6.12;ig2=3.11;ig3=1.69;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); a=-19.31;a1=296;a2=-165;a3=40.9;a4=-3.85; c=1000; tq=a+a1*(n/c)+a2*(n/c).^2+a3*(n/c).^3+a4*(n/c).^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; plot(ua1,D1,ua2,D2,ua3,D3,ua4,D4) title('汽车动力特性图'); xlabel('ua(km/h)'); ylabel('D'); gtext('Ⅰ') gtext('Ⅱ') gtext('Ⅲ') gtext('Ⅳ') 5、图解手工绘制Ⅱ档起步，加速至70km/h的车速—时间曲线以及距离--时间曲线 m=3695;g=9.8; G=m*g; nmin=600;nmax=4500; ig=[6.12 3.11 1.69 1.00]; i0=5.83; nt=0.87+0.025; f=0.012-0.0025; r=0.37; cda=2.60; If=0.22;Iw1=1.80;Iw2=3.60; u1=0.377*r*nmin./ig/i0; u2=0.377*r*nmax./ig/i0; deta=0*ig; for i=1:4 deta(i)=1+(Iw1+Iw2)/(m*r^2)+(If*(ig(i))^2*i0^2*nt)/(m*r^2); end ua=[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:N k=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; else 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; end a=delta(1:k); t(i)=sum(a); end plot(t,ua); axis([0 30 0 80]); title('汽车Ⅱ档起步加速至70km/h的车速--时间曲线'); xlabel('时间t（s）'); ylabel('速度ua（km/h)'); zoom on [x,y]=ginput(1); zoom off; disp('汽车Ⅱ档起步加速至70km/h的加速时间');disp(x);disp('s'); 汽车Ⅱ档起步加速至70km/h的加速时间t=20.0115s ２ 汽车燃料经济性计算（等速、多工况） 例如，已知汽车结构参数同题1，负荷特性拟合公式为 N/(rmin-1) 　 B0 B1 B2 B3 B4 820 1427 -416 72 -6.0 0.18 1200 1355 -304 37 -2.05 0.043 1600 1284 -190 15 -0.51 0.007 2000 1123 -121.6 7.0 -0.185 0.0019 2600 1141 -99 4.5 -0.091 0.0007 3000 1051 -74 2.86 -0.051 0.00035 3400 1233 -85 3.0 -0.0475 0.0003 3880 1130 -45 0.71 -0.0008 -0.00004 怠速油耗为0.3ml/s（400r/min），求 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。 3) 按6工况循环行驶的百公里油耗。计算中确定燃油消耗率值b时，若发动机转速与负荷特性中给定的转速不相等，可根据相邻转速的两根曲线用插值法求得。 1、汽车功率平衡图 m=3695; g=9.8; r=0.37; nt=0.87+0.025; f=0.0125-0.0025; cda=2.60; If=0.22;Iw1=1.80;Iw2=3.60; i0=5.83; ig=[6.12 3.11 1.69 1.00]; for i=1:79 n(i)=(i+11)*50; a=-19.31;a1=296;a2=-165;a3=40.9;a4=-3.85; c=1000; Tq(i)=a+a1*(n(i)/c)+a2*(n(i)/c).^2+a3*(n(i)/c).^3+a4*(n(i)/c).^4; end for j=1:4 for i=1:79 ua(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; end end plot(ua,Pe,ua,Pfw) title('功率平衡图'); xlabel('ua(km/h)'); ylabel('Pe,Pfw(kw)'); gtext('Ⅰ') gtext('Ⅱ') gtext('Ⅲ') gtext('Ⅳ') gtext('(Pf+Pw)/ηt') 2、最高档与次高档的等速百公里油耗曲线 1）最高档等速百公里油耗曲线 r=0.37;nt =0.87+0.025; f=0.0125-0.0025; m=3695;g=9.81;G=m.*g; cda=2.60;pg=7.12; i0=5.83; ig3=1.69;ig4=1; n=[800 1200 1600 2000 2600 3000 3400 3800]; B0=[1427 1355 1284 1123 1141 1051 1233 1130]; B1=[-416 -304 -190 -121.6 -99 -74 -85 -45] ; B2=[72 37 15 7.0 4.5 2.86 3.0 0.71]; B3=[-6.0 -2.05 -0.51 -0.185 -0.091 -0.051 -0.0475 -0.0008]; B4=[0.18 0.043 0.007 0.0019 0.0007 0.00035 0.0003 -0.00004]; ua=(0.377*r*n)/(ig4*i0); a=-19.31;a1=296;a2=-165;a3=40.9;a4=-3.85; c=1000; tq=a+a1*(n/c)+a2*(n/c).^2+a3*(n/c).^3+a4*(n/c).^4; P=(1/nt)*(G*f*ua/3600+cda*ua.^3/76140); b=B0+B1.*P+B2.*P.^2+B3.*P.^3+B4.*P.^4; Qs=P.*b./(1.02*ua*pg); b=polyfit(ua,Qs,3); ua4=8:1:100; f=polyval(b,ua4); figure; plot(ua,Qs,'k.',ua4,f,'LineWidth',2); title('汽车最高档等速百公里油耗曲线'); xlabel('ua/(km/h)'); ylabel('Qs/[1/L(100km)]'); 2）次高档等速百公里油耗曲线 r=0.37;nt =0.87+0.025; f=0.0125-0.0025; m=3695;g=9.81;G=m.*g;cda=2.60;pg=7.12;i0=5.83; ig3=1.69;ig4=1; n=[800 1200 1600 2000 2400 2800 3200 3600]; B0=[1427 1355 1284 1123 1141 1051 1233 1130]; B1=[-416 -304 -190 -121.6 -99 -74 -85 -45] ; B2=[72 37 15 7.0 4.5 2.86 3.0 0.71]; B3=[-6.0 -2.05 -0.51 -0.185 -0.091 -0.051 -0.0475 -0.0008]; B4=[0.18 0.043 0.007 0.0019 0.0007 0.00035 0.0003 -0.00004]; ua=(0.377*r*n)/(ig3*i0); a=-19.31;a1=296;a2=-165;a3=40.9;a4=-3.85; c=1000; tq=a+a1*(n/c)+a2*(n/c).^2+a3*(n/c).^3+a4*(n/c).^4; P=(1/nt)*(G*f*ua/3600+cda*ua.^3/76140); b=B0+B1.*P+B2.*P.^2+B3.*P.^3+B4.*P.^4; Qs=P.*b./(1.02*ua*pg); b=polyfit(ua,Qs,3); ua3=8:1:55; f=polyval(b,ua3); figure; plot(ua,Qs,'k.',ua3,f,'LineWidth',2); title('汽车次高档等速百公里油耗曲线'); xlabel('ua/(km/h)'); ylabel('Qs/[1/L(100km)]'); 3、按6工况循环形式的百公里耗油 clear; m=3695; g=9.81; G=m*g; pg=7.00; Iw1=1.80;Iw2=3.60;Iw=Iw1+Iw2; If=0.22; f=0.0125-0.0025; nt=0.87+0.025; cda=2.60; r=0.37; i0=5.83; ig=[3.55 2.77 1.65 1.00 0.83]; a=-19.31;a1=296;a2=-165;a3=40.9;a4=-3.85; c=1000; for i=1:137, n(i)=(i+23)*25; end for i=1:137, Tq(i)=a+a1*(n(i)/c)+a2*(n(i)/c).^2+a3*(n(i)/c).^3+a4*(n(i)/c).^4; end for j=1:5 for i=1:137 ua(i,j)=0.377*r*n(i)/ig(j)/i0; Pz(i,j)=(G*f*ua(i,j)/3600+cda*ua(i,j)^3/76140)/nt; end end n0=[815 1207 1614 2012 2603 3006 3403 3804]; B0=[1427 1355 1284 1123 1141 1051 1233 1130]; B1=[-416 -304 -190 -121.6 -99 -74 -85 -45] ; B2=[72 37 15 7.0 4.5 2.86 3.0 0.71]; B3=[-6.0 -2.05 -0.51 -0.185 -0.091 -0.051 -0.0475 -0.0008]; B4=[0.18 0.043 0.007 0.0019 0.0007 0.00035 0.0003 -0.00004]; for j=1:5 for i=1:8 Tq(i)=a+a1*(n0(i)/c)+a2*(n0(i)/c).^2+a3*(n0(i)/c).^3+a4*(n0(i)/c).^4; ub(i,j)=0.377*r*n0(i)/ig(j)/i0; Peb(i)=Tq(i)*n0(i)/9549; b(i)=B0(i)+B1(i)*Peb(i)+B2(i)*Peb(i)^2+B3(i)*Peb(i)^3+B4(i)*Peb(i)^4; end end ub1=ub(:,1)'; ub2=ub(:,2)'; ub3=ub(:,3)'; ub4=ub(:,4)'; ub5=ub(:,5)'; b1=polyfit(ub1,b,3); b2=polyfit(ub2,b,3); b3=polyfit(ub3,b,3); b4=polyfit(ub4,b,3); b5=polyfit(ub5,b,3); for k=1:137 bh(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)); end for i=1:5 for k=1:137 Q(k,i)=Pz(k,i)*bh(k,i)/(1.02*ua(k,i)*pg); end end ua(1)=40; P1=(G*f* ua(1)/3600+cda*ua(1)^3/76140)/nt; ba1=interp1(ub4,b,ua(1)); Q1=P1*125*ba1/(102*ua(1)*pg); a=1+Iw/(m*r^2)+If*ig(3)^2*i0^2*nt/(m*r^2); Q2=0; t1=1/(0.2*3.6); for i=1:10 u2(1)=ua(1); u2(i+1)=u2(i)+ 1; P2(i)=(G*f* u2(i)/3600+cda*u2(i)^3/76140+a*m*u2(i)*0.2/3600)/nt; P2(i+1)=(G*f*u2(i+1)/3600+cda*u2(i+1)^3/76140+a*m*u2(i+1)*0.2/3600)/nt; b2(i)=interp1(ub4,b,u2(i)); b2(i+1)=interp1(ub4,b,u2(i+1)); Q2t(i)=P2(i)*b2(i)/(367.1*pg); Q2t(i+1)=P2(i+1)*b2(i+1)/(367.1*pg); Q2a(i)=(Q2t(i)+Q2t(i+1))*t1/2; Q2=Q2+Q2a(i); end ua(3)=50; P3=(G*f* ua(3)/3600+cda*ua(3)^3/76140)/nt; ba3=interp1(ub4,b,ua(3)); Q3=P3*ba3*250/(102*ua(3)*pg); Q4=0; t2=1/(0.17*3.6); for i=1:10 u4(1)=ua(3); u4(i+1)=u4(i)+ 1; P4(i)=(G*f* u4(i)/3600+cda*u4(i)^3/76140+a*m*u4(i)*0.17/3600)/nt; P4(i+1)=(G*f* u4(i+1)/3600+cda*u4(i+1)^3/76140+a*m*u4(i+1)*0.17/3600)/nt; b4(i)=interp1(ub4,b,u4(i)); b4(i+1)=interp1(ub4,b,u4(i+1)); Q4t(i)=P4(i)*b4(i)/(367.1*pg); Q4t(i+1)=P4(i+1)*b4(i+1)/(367.1*pg); Q4a(i)=(Q4t(i)+Q4t(i+1))*t2/2; Q4=Q4+Q4a(i); end ua(5)=60; P5=(G*f* ua(5)/3600+cda*ua(5)^3/76140)/nt; ba5=interp1(ub4,b,ua(5)); Q5=P3*ba5*250/(102*ua(5)* pg); Qid=0.299; Q6=(60-40)*Qid/(3.6*0.26); Qs=(Q1+Q2+Q3+Q4+Q5+Q6)*100/1350; disp('循环六工况百公里油耗Qs='); disp(Qs); disp('L/100Km'); 运行结果： 循环六工况百公里油耗Qs=15.6405 L/100Km