1、汽车主减速器传动比优化汽车主减速器传动比的优化专业班级:车辆11级2班姓名:韦永亮学号:2011 1097某轻型货车,发动机型号为492QC-2,车有关数据如下。发动机的最低转速nmin600r/min,最高转速nmax=4000r/min。整车质量2000kg;整车装备质量1800kg总质量3880kg;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;主减速器传动比i05.83;飞轮转动惯量If0.218kg.m2;二前轮转动惯量Iw11.798kg.m2;后四轮转动惯量Iw23.598kg.m2;1档2档3档4档5档变速
2、器传动比5.562.7691.6441.000.793汽油发动机使用外特性的Tq-n曲线的拟合公式为:Tq=-19.313+295.27*(n/1000)-165.44*(n/1000)2+40.874*(n/1000)3-3.8445*(n/1000)4.负荷特性曲线拟合公式为:b=B0+B1*Pe+B2*Pe.2+B3*Pe.3+B4*Pe.4.拟合公式中的系数为:N/(r/min)B0B1B2B3B48151326.8-416.4672.379-5.86290.1776812071354.7-303.9836.657-2.05530.04307216141284.4-189.751452
3、.4-0.511840.006816420121122.9-121.597.0035-0.185170.001855526031141.0-98.8934.4763-0.0910770.0006890630061051.2-73.7142.8593-0.051380.0003503234031233.9-84.4782.9788-0.0474490.0002823038041129.7-45.2910.71113-0.00075215-0.000038568怠速油耗Qid0.299mL/s(怠速转速400r/min)。一.建模1.优化变量我们主要考虑,在汽车变速器传动比不变的情况下,汽车主减速
4、器传动比对经济性和动力性的影响。所以以主减速器传动比i0作为优化变量。X=i02.目标函数 针对该货车,主要考虑优化经济性,这样的话要求在必要的动力性条件下,要求最小的燃油消耗,即要求百公里油耗尽可能少。 q=minf(X)3.约束条件 (1)最高车速要求 maxUa(X)=100km/h (2)动力性要求 t(x)=32.5% (4)最高档动力因数校核 D0=D0=0.03 二计算求解1.计算加速时间nT=0.85; r=0.367; f=0.013; CDA=2.77; If=0.218;Iw1=1.798; Iw2=3.598; L=3.2; a=1.947; hg=0.9; m=388
5、0;g=9.8; G=m*g; ig=5.56,2.769,1.644,1.00,0.793;nmin=600; nmax=4000; i0=5.43;u=0.377*r*nmax./ig/i0; for i=1:5 deta(i)=1+(Iw1+Iw2)/(m*r2)+(If*(ig(i)2*i02*nT)/(m*r2);%旋转质量换算系数endua=6:0.01:100; %最低稳定车速6公里每小时N=length(ua);n=0;Tq=0;Ft=0;inv_a=0;delta=0*ua; %数据初始化Ff=G*f;Fw=CDA*ua.2/21.15;for i=1:N k=i; if u
6、a(i)=u(2) %以二档起步计算 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); %加速度倒数 delta(i)=0.01*inv_a(i)/3.6; %加速时间 elseif ua(i)=u(3) n=ua(i)*(ig(3)*i0/r)/0.377; Tq=-19.313+295.27*(n/1000)-165.
7、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; elseif ua(i)=u(4) 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)/(
8、Ft-Ff-Fw(i); delta(i)=0.01*inv_a(i)/3.6; else n=ua(i)*(ig(5)*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(5)*i0*nT/r; inv_a(i)=(deta(5)*m)/(Ft-Ff-Fw(i); delta(i)=0.01*inv_a(i)/3.6; enda=delta(1:k); %定义矩阵t(i)=sum(a); %求和endplot(t,ua);axis(0 80 0
9、 100);title(汽车二档原地起步换挡加速时间曲线);xlabel(时间t(s));ylabel(速度ua(km/h));x,y=ginput(1);disp(x);考虑到该货车的最高车速很难达到100km/h(i0为5.83时不到100km/h)以加速到70公里的时间作为加速时间。改变i0的值得到不同的加速时间如下表。i05.175.435.836.016.176.33t(s) 26.2673 26.4516 25.8986 25.5300 25.161324.79262.计算六工况百公里油耗。n=600:1:4000;m=3880;g=9.8;G=m*g; i0=6.01; ig=5
10、.56 2.769 1.644 1.00 0.793; nT=0.85;r=0.367;f=0.013;CDA=2.77; L=3.2;a=1.947;hg=0.9;If=0.218;Iw1=1.798;Iw2=3.598;n0=815 1207 1614 2012 2603 3006 3403 3804; B00=1326.8 1354.7 1284.4 1122.9 1141.0 1051.2 1233.9 1129.7; B10=-416.46 -303.98 -189.75 -121.59 -98.893 -73.714 -84.478 -45.291;B20=72.379 36.65
11、7 14.524 7.0035 4.4763 2.8593 2.9788 0.71113; B30=-5.8629 -2.0553 -0.51184 -0.18517 -0.091077 -0.05138 -0.047449 -0.00075215; B40=0.17768 0.043072 0.0068164 0.0018555 0.00068906 0.00035032 0.00028230 -0.000038568; B0=spline(n0,B00,n); B1=spline(n0,B10,n); B2=spline(n0,B20,n); B3=spline(n0,B30,n);B4=
12、spline(n0,B40,n);Ff=G*f; ua5=0.377*r*n/ig(5)/i0;Fz5=Ff+CDA*(ua5.2)/21.15; Pe5=Fz5.*ua5./(nT*3.6*1000);for i=1:1:3401 b5(i)=B0(i)+B1(i)*Pe5(i)+B2(i)*Pe5(i).2+B3(i)*Pe5(i).3+B4(i)*Pe5(i).4; endpg=6.86;Qt5=Pe5.*b5/(367*pg);plot(ua5,Qt5);hold on;axis(0 100 0 15);title(油耗曲线); xlabel(ua(km/h);ylabel(单位时间油
13、耗ml/s); for i=20:1:50 y(i)= interp1(ua5,Qt5,i,cubic) %插值(立方)不同速度下单位时间油耗 enddt1=16.7/15; %每加速一公里时间dt2=14/10;y1= y(26) y(27) y(28) y(29) y(30) y(31) y(32) y(33) y(34) y(35) y(36) y(37) y(38) y(39)y2=y(41) y(42) y(43) y(44) y(45) y(46) y(47) y(48) y(49)qd=19.3*0.299; %怠速油耗qj1=0.5*(y(25)+y(40)*dt1+sum(y
14、1,2)*dt1;qj2=0.5*(y(40)+y(50)*dt2+sum(y2,2)*dt2; %加速段油耗qy=y(25)*7.2+y(40)*22.5+y(50)*18; %匀速段油耗qz1=(qd+qj1+qj2+qy)*100/1.075 %总油耗,1.075为六工况下的行驶距离.改变i0的值(取六个不同的值)分别求得各自百公里油耗如下表。i05.175.435.836.016.176.33Q(L)10.439L10.615L10.89L11.013L11.122L11.232L3.绘制燃油经济性-加速时间曲线。q=10.439 10.615 10.753 10.89 11.013 11.122 11.232;t= 25.8986 25.8986 26.0829 25.8986 25.5300 25.3456 24.7926;plot(q,t,+r);hold on q1=linspace(q(1),q(6),10
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