汽车理论课后题matlab程序文件.doc

1.3
n=600:1:4000; r=0.367; i0=5.83; eff=0.85; f=0.013;
m=3880; g=9.8; G=m*g; CdA=2.77; a=1.947; hg=0.9; L=3.2;
Iw1=1.798; Iw2=3.598; Iw=Iw1+Iw2; 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
for ig=[5.56,2.769,1.644,1.00,0.793]
Ua=0.377*r*n/ig/i0;
Ft=Ttq*ig*i0*eff/r;
plot(Ua,Ft);
hold on;
end
Ff=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');
gtext('Ft1'),gtext('Ft2'),gtext('Ft3'),gtext('Ft4'),gtext('Ft5'),gtext('Ff+Fw')
[x,y]=ginput(1); disp('汽车的最高车速');disp(x);disp('km/h');
%最大爬坡度与最大爬坡度时的附着率
Ua=0.377*r*n/5.56/i0;
Ft=Ttq*5.56*i0*eff/r;
Fw=CdA*Ua.^2/21.15;
i=tan(asin((Ft-(Ff+Fw))/G));
disp('汽车的最大爬坡度');disp(max(i));
C=max(i)/(a/L+hg/L*max(i));
disp('克制最大爬坡度时的附着率');disp(C);
%加速度倒数曲线
figure;
for ig=[5.56,2.769,1.644,1.00,0.793]
Ua=0.377*r*n/ig/i0;
q=1+Iw/(m*r^2)+If*ig^2*i0^2*eff/(m*r^2);
Ft=Ttq*ig*i0*eff/r;
Fw=CdA*Ua.^2/21.15;
as=(Ft-(Ff+Fw))/q/m;
plot(Ua,1./as);
hold on;
end
axis([0 98 0 10]);
title('行驶加速度倒数曲线');xlabel('Ua/(km/h)');ylabel('1/a');
gtext('1/a1'),gtext('1/a2'),gtext('1/a3'),gtext('1/a4'),gtext('1/a5');
%加速时间曲线
u(1)=0.377*r*600/i0/2.769;dt=0.01;w=1;t(1)=0;ig=2.769;
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;
Ft(w)=Ttq(w)*ig*i0*eff/r;
Ff=G*f;
Fw(w)=CdA*u(w)^2/21.15;
q=1+Iw/(m*r^2)+If*ig^2*i0^2*eff/(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/2.769/i0)
ig=1.644;
end
if(u(w+1)>=0.377*4000*r/1.644/i0)
ig=1.00;
end
if(u(w+1)>=0.377*4000*r/1.00/i0)
ig=0.793;
end
t(w+1)=(w+1)*dt;
w=w+1;
end
figure;plot(t,u);axis([0 60 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);

1.8
Iw1=2.25; Iw2=2.25; Iw=Iw1+Iw2; If=0.25; m=1600; g=9.8;G=m*g;
Ttqmax=140; i1=3.85; i0=4.08; eff=0.9; r=0.3; hg=0.63; b=1.25; L=2.7;
q=1+Iw/(m*r^2)+If*i1^2*i0^2*eff/(m*r^2);
Ft=Ttqmax*i1*i0*eff/r;
a=Ft/q/m;
q=a/g;
C1=q/(b/L-hg/L*q);
if(C1>0.6)
disp('发动机转矩不能充分发挥');
else
disp('发动机转矩能够充分发挥');
end
b=(q/0.6+hg/L*q)*L;
disp('调整后的b值');disp(b);
disp('调整后的前轴负荷率'),disp(b/L);

1.9
Iw=3.6; If=0.22; m=2152; g=9.8; r=0.367; eff=0.9; i4=1; i0=4.55;
amax=0.75; Ua=50/3.6; CdA=1.5;
q=1+Iw/(m*r^2);
f=q*0.59/3.6/g;
disp('汽车在该路面上的滚动阻力系数');disp(f);
q=1+Iw/(m*r^2)+If*i4^2*i0^2*eff/(m*r^2);
D4max=f+q*amax/g;
disp('最大动力因数');disp(D4max);
Fw=CdA*Ua^2/21.15;
D1max=(D4max*G+Fw)*i1/i4/G;
imax=tan(asin((D1max-f*sqrt(1-D1max^2+f^2))/(1+f^2)));
disp('最大爬坡度'),disp(imax);
2.7
n=600:1:4000; r=0.367; i0=5.83; eff=0.85; f=0.013;CdA=2.77;m=3880; g=9.8; G=m*g;
Ttq=-19.313+295.27*n/1000-165.44*(n/1000).^2+40.874*(n/1000).^3-3.8445*(n/1000).^4;
for ig=[5.56,2.769,1.644,1.00,0.793]
Ua=0.377*r*n/ig/i0;
Pe=Ttq.*n/9550;
plot(Ua,Pe);
hold on;
end
Ua=0:0.1:max(Ua);
Pf=G*f*Ua/3600;
Pw=CdA*Ua.^3/76140;
plot(Ua,(Pf+Pw)/eff);
title('汽车的功率平衡图'),xlabel('Ua/(km/h)'),ylabel('P/kw');
%等速百公里燃油消耗
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=[72.379,36.657,14.524,7.0035,4.4763,2.8593,2.9788,0.71113];
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);
deng=7;
figure;
for ig=[1.00,0.793]
Ua=0.377*r*n/ig/i0;
Pf=G*f*Ua/3600;
Pw=CdA*Ua.^3/76140;
P=(Pf+Pw)/eff;
b=B0+B1.*P+B2.*P.^2+B3.*P.^3+B4.*P.^4;
Q=P.*b./(1.02*Ua*deng);
plot(Ua,Q);
hold on;
end
axis([0 100 12 28]);
title('最高挡与次高挡等速百公里油耗曲线'),xlabel('Ua/(km/h)'),ylabel('百公里油耗Qs/(L/100km)');

4.3
beta=0.38; L=3.95; a1=2.1; b1=L-a1; hg1=0.845;
a2=2.95; b2=L-a2; hg2=1.17;g=9.8;
z=0:0.01:1;
faif1=beta*z./(1/L*(b1+z*hg1));
fair1=(1-beta)*z./(1/L*(a1-z*hg1));
faif2=beta*z./(1/L*(b2+z*hg2));
fair2=(1-beta)*z./(1/L*(a2-z*hg2));
plot(z,faif1,'r',z,fair1,'g',z,faif2,'b',z,fair2,'k');
fai=0:0.01:1;
Ef1=(b1/L)./(beta-fai*hg1/L);
Er1=(a1/L)./((1-beta)+fai*hg1/L);
Ef2=(b2/L)./(beta-fai*hg2/L);
Er2=(a2/L)./((1-beta)+fai*hg2/L);
figure;
plot(fai,Ef1,'r',fai,Er1,'g',fai,Ef2,'b',fai,Er2,'k');
axis([0 1 0 1]);
fai=0.8;
Er1=(a1/L)/((1-beta)+fai*hg1/L);
Er2=(a2/L)/((1-beta)+fai*hg2/L);
abmax1=fai*Er1*g;
abmax2=fai*Er2*g;
t21=0.02; t22=0.2; u0=30;
s1=1/3.6*(t21+t22/2)*u0+u0^2/25.92/abmax1;
s2=1/3.6*(t21+t22/2)*u0+u0^2/25.92/abmax2;
disp('空载时的制动距离'),disp(s1);
disp('满载时的制动距离'),disp(s2);
%前部管路损坏时制动距离
z1=a1*fai/(L+fai*hg1); z2=a2*fai/(L+fai*hg2);
abmax1=z1*g; abmax2=z2*g;
s1=1/3.6*(t21+t22/2)*u0+u0^2/25.92/abmax1;
s2=1/3.6*(t21+t22/2)*u0+u0^2/25.92/abmax2;
disp('前部管路损坏时空载制动距离');disp(s1);
disp('前部管路损坏时满载制动距离');disp(s2);
%后部管路损坏时的制动距离
z1=b1*fai/(L-fai*hg1);z2=b2*fai/(L-fai*hg2);
abmax1=z1*g; abmax2=z2*g;
s1=1/3.6*(t21+t22/2)*u0+u0^2/25.92/abmax1;
s2=1/3.6*(t21+t22/2)*u0+u0^2/25.92/abmax2;
disp('后部管路损坏时空载制动距离');disp(s1);
disp('后部管路损坏时满载制动距离');disp(s2);
4.5
hg=0.63; b=1.25; L=2.7; beta=0.65; fai=0.7; g=9.8;
fai0=(L*beta-b)/hg;
if(fai<fai0)
disp('前轮先抱死,制动效率为'); E=(b/L)/(beta-fai*hg/L);
else
disp('后轮先抱死,制动效率为'); E=(a/L)/((1-beta)+fai*hg/L);
end
disp('最大制动减速度'),disp(E*fai*g);
disp('a)、b)、c)的双回路制动系统制动系增益都为G');
disp('1回路失效时，a)、b)、c)的制动系增益分别为0.35,0.5,0.5');
disp('1回路失效时，a)、b)、c)的制动系增益分别为0.65,0.5,0.5');
disp('a)中1回路失效时最大制动强度');zmax1=a*fai/(L+fai*hg)
disp('a)中1回路失效时制动效率');disp(zmax1/fai)
disp('a)中1回路失效时最大制动减速度');abmax1=zmax1*g
disp('a)中2回路失效时最大制动强度');zmax2=a*fai/(L+fai*hg)
disp('a)中1回路失效时制动效率');disp(zmax1/fai)
disp('a)中2回路失效时最大制动减速度');abmax2=zmax2*g
disp('b)或c)中1或2回路失效时最大制动强度');z=fai*b/(2*L*beta-fai*hg)
disp('b)或c)中1或2回路失效时最大制动减速度');abmax=z*g
disp('b)或c)中1或2回路失效时制动效率');disp(z/fai)
disp('双回路系统a制动系增益最大，一个回路失效时的最大制动减速度也比b、c大，所以其性能较优')
disp('b和c制动系增益一样,两者在一个回路失效时的制动效率一样。但是，c在一个回路失效时，制动力作用在一侧车轮上,会产生跑偏等问题')

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