汽车主减速器传动比优化

1、 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nmin600r/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nT0.85；滚动阻力系数f0.013；空气阻力系数*迎风面积CDA2.77m2；飞轮转动惯量If0.218kg.m2；二前轮转动惯量Iw11.798kg.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Iw23.598kg.m2；T=-19.313+295.27*(n/1000)-165.44*(n/1000).2+40.874*(n/1000

2、).3-3.8445*(n/1000).4;怠速油耗Qid0.299mL/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)B0B1B2B3B48151326.8-416.4672.379-5.86290.1776812071354.7-303.9836.657-2.05530.04307216141284.4-189.751452.4-0.511840.006816420121122.9-121.597.0035-0.185170.001855526031141.0-98.8934.4763-0.0

3、910770.0006890630061051.2-73.7142.8593-0.051380.0003503234031233.9-84.4782.9788-0.0474490.0002823038041129.7-45.2910.71113-0.00075215-0.0000385681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; I

4、w=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)/100

5、0)3-3.8445*(n(w)/1000)4; Ft(w)=Ttq(w)*ig*i0*nT/r; Ff=G*f; Fw(w)=CdA*u(w)2/21.15; q=1+Iw/(m*r2)+If*ig2*i02*nT/(m*r2); 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/4.016/i0) ig=3.09; end if(u(w+1)>=0.377*4000*r/3.09/i0) ig=1.71; end if(u(w+1)>=0.377*4000*r/1.71/

6、i0) ig=1; end t(w+1)=(w+1)*dt; w=w+1;endfigure;plot(t,u);axis(0 80 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); 以加速到70公里的时间作为加速时间。io5.0895.445.856.016.17加速时间24.055324.239624.055323.871023.68662计算六工况百公

7、里油耗%等速百公里油耗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;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=72.379,36.657,14.524,7.0035,4.4763,2.8

8、593,2.9788,0.71113;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);pg=7;ig=1.00; Ua=0

9、.377*r*n/ig/i0; Pf=G*f*Ua/3600; Pw=CdA*Ua.3/76140; P=(Pf+Pw)/nT; b=B0+B1.*P+B2.*P.2+B3.*P.3+B4.*P.4; Q=P.*b./(1.02*Ua*pg); Iw1=1.798; Iw2=3.598; Iw=Iw1+Iw2; If=0.218;pg=7;Ff=G*f; ua1=25,40,50;Fw=CdA*ua1.2/21.15;Pa=(Ff+Fw).*ua1/3600/nT;b=spline(P,b,Pa);s=50,250,250;Q1=s.*Pa.*b./(102*ua1*pg);disp(Q1);

10、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*r2)+If*ig2*i02*nT/(m*r2);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=spli

11、ne(Pa,b,Pa);Qs=Pa.*b/(367.1*pg);t=1/(3.6*a);Q21=0;for n=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*r2)+If*ig2*i02*nT/(m*r2);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,b

12、3,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;for n=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)13.00

13、0613.408613.739913.853513.96823. 绘制燃油经济性-加速时间曲线Q= 13.0006 13.4086 13.7399 13.8535 13.9682;t= 24.0553 24.2396 24.0553 23.8710 23.6866;plot(Q,t,'+r');hold on q1=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/100k

14、m)');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');4. 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.

15、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for ig=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); 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/

16、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=5.089 5.44 5.85 6.01 6.17;umax=102.4 102.1 100.2 99.2 97.9;plot(i0,umax,'+r');hold on i01=linspace(i0(1),i0(5); umax1=spline(i0,umax,i01); plot(i01,umax1); title('i0-umax曲线');xlabel('i0'

17、;);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5.089 5.44 5.856. 绘制i0-t图（求加速时间约束下临界i0值）i0=5.089 5

18、.44 5.85 6.01 6.17;t= 24.0553 24.2396 24.0553 23.8710 25.6866;plot(i0,t,'+r');hold on ；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');zoom on;x,y=ginput(1);zoom off;disp('临界i0=');disp(x); gtext(&

19、#39;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5.089 5.44 5.85 6.01 7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

20、*n/1000-165.44*(n/1000).2+40.874*(n/1000).3-3.8445*(n/1000).4;ig=5.06 4.016 3.09 1.71 1;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(%)2

21、8.973131.274134.013335.1017 36.2011绘制i0-i曲线（求最大爬坡度约束下i0)i0=5.089 5.44 5.85 6.01 6.17;i=28.9731 31.2741 34.0133 35.1017 36.2011;plot(i0,i,'+r'); hold on i01=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5.85 6.01 6.17。