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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
2、.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)B0B1B2B3B48151326.8-416.4672.379-5.86290.1776812071354.7-303.9836.657-2.05530.0430
3、7216141284.4-189.751452.4-0.511840.006816420121122.9-121.597.0035-0.185170.001855526031141.0-98.8934.4763-0.0910770.0006890630061051.2-73.7142.8593-0.051380.000350321634031233.9-84.4782.9788-0.0474490.0002823038041129.7-45.2910.71113-0.00075215-0.0000
4、385681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
5、).^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;16Ft(w)=Ttq(w)*ig*i0*nT/r;F
6、f=G*f;Fw(w)=CdA*u(w)^2/21.15;q=1+Iw/(m*r^2)+If*ig^2*i0^2*nT/(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/4.016/i0)ig=3.09;endif(u(w+1)>=0.377*4000*r/3.09/i0)ig=1.71;endif(u(w+1)>=0.377*4000*r/1.71/i0)ig=1;endt(w+
7、1)=(w+1)*dt;w=w+1;endfigure;plot(t,u);axis([0800100]);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。16io5.0895.445.856.016.17加速时间24.055324.239624.055323.871023.68662计算六工况百公
8、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];16b0=[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
