汽车主减速器传动比优化

汽车主减速器传动比优化汽车主减速器传动比优化某轻型货车，车有关数据如下：发动机的最低转速nmin＝600r/min，最高转速nmax=4000r/min。总质量3650kg；车轮半径0.367m；传动系机械效率nT＝0.85；滚动阻力系数f＝0.013；空气阻力系数*迎风面积CDA＝2.77m2；飞轮转动惯量If＝0.218kg.m2；二前轮转动惯量Iw1＝1.798kg.m2;轴距L=3.2m;质心至前轴距离（满载）a=1.947m；质心高（满载）hg=0.9m；四后轮转动惯量Iw2＝3.598kg.m2；T=-19.313+295.27*(n/1000)-165.44*(n/1000).^2+40.874*(n/1000).^3-3.8445*(n/1000).^4;怠速油耗Qid＝0.299mL/s（怠速转速400r/min）。负荷特性曲线拟合公式为：b=B0+B1*Pe+B2*Pe.^2+B3*Pe.^3+B4*Pe.^4.N/(r/min)B0B1B2B3B48151326.8-416.4672.379-5.86290.1776812071354.7-303.9836.657-2.05530.04307216141284.4-189.751452.4-0.511840.006816420121122.9-121.597.0035-0.185170.001855526031141.0-98.8934.4763-0.0910770.0006890630061051.2-73.7142.8593-0.051380.0003503234031233.9-84.4782.9788-0.0474490.0002823038041129.7-45.2910.71113-0.00075215-0.0000385681档2档3档4档5档变速器传动比5.064.0163.091.711计算1计算加速时间Matlab程序：n=600:1:4000;m=3650;g=9.8;G=m*g;r=0.367;i0=5.089;nT=0.85;f=0.013;CdA=2.77;Iw1=1.798;Iw2=3.598;Iw=Iw1+Iw2;If=0.218;a=1.947;hg=0.9;L=3.2;Ttq=-19.313+295.27*n/1000-165.44*(n/1000).^2+40.874*(n/1000).^3-3.8445*(n/1000).^4;%以2挡加速时间计算u(1)=0.377*r*600/i0/4.016;dt=0.01;w=1;t(1)=0;ig=4.016;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;s=[50,250,250];Q1=s.*Pa.*b./(102*ua1*pg);disp(Q1);Q1=Q1(1)+Q1(2)+Q1(3);%匀加速行驶的油耗%第一段ua=25:1:40;a=0.25;q=1+Iw/(m*r^2)+If*ig^2*i0^2*nT/(m*r^2);Pa=(G*f*ua/3600+CdA*ua.^3/76140+q*m*ua.*a/3600)/nT;n=ua*ig*i0/0.377/r;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);b=B0+B1.*Pa+B2.*Pa.^2+B3.*Pa.^3+B4.*Pa.^4;b=spline(Pa,b,Pa);Qs=Pa.*b/(367.1*pg);t=1/(3.6*a);Q21=0;forn=1:15Q21=Q21+(Qs(n)+Qs(n+1))*t/2;enddisp(Q21);%第二段ua=40:1:50;a=0.20;q=1+Iw/(m*r^2)+If*ig^2*i0^2*nT/(m*r^2);Pa=(G*f*ua/3600+CdA*ua.^3/76140+q*m*ua.*a/3600)/nT;n=ua*ig*i0/0.377/r;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);b=B0+B1.*Pa+B2.*Pa.^2+B3.*Pa.^3+B4.*Pa.^4;b=spline(Pa,b,Pa);Qs=Pa.*b/(367.1*pg);t=1/(3.6*a);Q22=0;forn=1:10Q22=Q22+(Qs(n)+Qs(n+1))*t/2;enddisp(Q22);Q2=Q21+Q22;%匀减速行驶的油耗Qid=0.299;t3=19.3;Q3=Qid*t3;disp(Q3);%总油耗s=1075;Q=(Q1+Q2+Q3)*100/1075;disp(Q);io5.0895.445.856.016.17Q(L)13.000613.408613.739913.853513.9682绘制燃油经济性-加速时间曲线Q=[13.000613.408613.739913.853513.9682];t=[24.055324.239624.055323.871023.6866];plot(Q,t,'+r');holdonq1=linspace(Q(1),Q(5),100);t1=spline(Q,t,q1);%三次样条插值plot(q1,t1);%绘制燃油经济性-加速时间曲线title('燃油经济性—加速时间曲线');xlabel('百公里油耗/(L/100km)');ylabel('加速时间/s');gtext('i0=5.089'),gtext('i0=5.44'),gtext('i0=5.85'),gtext('i0=6.01'),gtext('i0=6.17');计算最高车速n=600:1:4000;r=0.367;i0=5.089;nT=0.85;f=0.013;m=3650;g=9.8;G=m*g;CdA=2.77;a=1.947;hg=0.9;L=3.2;If=0.218;Ttq=-19.313+295.27*n/1000-165.44*(n/1000).^2+40.874*(n/1000).^3-3.8445*(n/1000).^4;%驱动力行驶阻力平衡图forig=[5.06,4.016,3.09,1.71,1]Ua=0.377*r*n/ig/i0;Ft=Ttq*ig*i0*nT/r;plot(Ua,Ft);holdon;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');i05.0895.445.856.016.17umax102.4102.1100.299.297.95.绘制i0-umax曲线（求最高车速约束条件下临界i0值）i0=[5.0895.445.856.016.17];umax=[102.4102.1100.299.297.9];plot(i0,umax,'+r');holdoni01=linspace(i0(1),i0(5));umax1=spline(i0,umax,i01);plot(i01,umax1);title('i0-umax曲线');xlabel('i0');ylabel('最高车速km/h');[x,y]=ginput(1);disp('临界i0=');disp(x);%根据最高车速约束条件，求临界i0值gtext('i0=5.089'),gtext('i0=5.44'),gtext('i0=5.85'),gtext('i0=6.01'),gtext('i0=6.17');临界i0=5.8855最高车速大于100km/h.所以io取5.0895.445.85绘制i0-t图（求加速时间约束下临界i0值）i0=[5.0895.445.856.016.17];t=[24.055324.239624.055323.871025.6866];plot(i0,t,'+r');holdon；i01=linspace(i0(1),i0(5));umax1=spline(i0,t,i01);plot(i01,umax1);title('i0-t曲线');xlabel('i0');ylabel('加速时间s');zoomon;[x,y]=ginput(1);zoomoff;disp('临界i0=');disp(x);gtext('i0=5.089'),gtext('i0=5.44'),gtext('i0=5.85'),gtext('i0=6.01'),gtext('i0=6.17');加速时间不超过25s所以io可以 取5.0895.445.856.017最大爬坡度计算n=600:1:4000;r=0.367;i0=5.089;eff=0.85;f=0.013;m=3650;g=9.8;G=m*g;CdA=2.77;a=1.947;hg=0.9;L=3.2;If=0.218;Ttq=-19.313+295.27*n/1000-165.44*(n/1000).^2+40.874*(n/1000).^3-3.8445*(n/1000).^4;ig=[5.064.0163.091.711];Ft1=Ttq*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;imax=100*tan(asin(max(Fi1/G)));disp('汽车最大爬坡度=');disp(imax);disp('%');i05.0895.445.856.016.17i(%)28.973131.274134.013335.101736.2011绘制i0-i曲线（求最大爬坡度约束下i0)i0=[5.0895.445.856.016.17];i=[28.973131.274134.013335.101736.2011];plot(i0,i,'+r');holdoni01=linspace(i0(1),i0(5),100);i1=spline(i0,i,i01);plot(i01,i1);title('i0-imax曲线');xlabel('i0');ylabel('imax(%)');[x,y]=ginput(1);disp('临界i0=');disp(x);gtext('i0=5.089'),gtext('i0=5.44'),gtext('i0=5.85'),gtext('i0=6.01'),gtext('i0=6.17');最大的爬坡度大于32%，因此io大于5.55,io可取5.856.016.17。8最高档动力因数校核一最大转矩计算n=600:1:4000;Tq=-19.313+295.27*(n/1000)-165.44*(n/1000).^2+40.874*(n/1000).^3-3.8445*(n/1000).^4;plot(n,Tq);holdon;title('n-Tq曲线');xlabel('转速nr/min');ylabel('转矩Tqn*m');[max_Tq,nn]=max(Tq);disp('最大值:');disp(max_Tq);disp('对应的n的值:');disp(n(nn));最大转矩174.9667最大转矩的转速2041二校核最高档的动力因数Tmax=174.9667;n=2041;CdA=2.77;nT=0.85;ig=1;r=0.367;m=3650;g=9.8;G=m*g;i0=[5.445.85];F=Tmax*i0*ig*nT/r;uat=0.377