汽车理论习题Matlab程序Word格式.docx
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汽车理论习题Matlab程序Word格式.docx
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0.793
轴距L=3.2m
质心至前轴距离(满载)a=1.974m
质心高(满载)hg=0.9m
解:
Matlab程序:
(1)求汽车驱动力与行驶阻力平衡图和汽车最高车速程序:
n=[600:
10:
4000];
Tq=-19.313+295.27*(n/1000)-165.44*(n/1000).^2+40.874*(n/1000).^3-3.8445*(n/1000).^4;
m=3880;
g=9.8;
nmin=600;
nmax=4000;
G=m*g;
ig=[5.562.7691.6441.000.793];
nT=0.85;
r=0.367;
f=0.013;
CDA=2.77;
i0=5.83;
L=3.2;
a=1.947;
hg=0.9;
If=0.218;
Iw1=1.798;
Iw2=3.598;
Ft1=Tq*ig
(1)*i0*nT/r;
Ft2=Tq*ig
(2)*i0*nT/r;
Ft3=Tq*ig(3)*i0*nT/r;
Ft4=Tq*ig(4)*i0*nT/r;
Ft5=Tq*ig(5)*i0*nT/r;
ua1=0.377*r*n/ig
(1)/i0;
ua2=0.377*r*n/ig
(2)/i0;
ua3=0.377*r*n/ig(3)/i0;
ua4=0.377*r*n/ig(4)/i0;
ua5=0.377*r*n/ig(5)/i0;
ua=[0:
5:
120];
Ff=G*f;
Fw=CDA*ua.^2/21.15;
Fz=Ff+Fw;
plot(ua1,Ft1,ua2,Ft2,ua3,Ft3,ua4,Ft4,ua5,Ft5,ua,Fz);
title('
驱动力-行驶阻力平衡图'
);
xlabel('
ua(km/s)'
ylabel('
Ft(N)'
gtext('
Ft1'
),gtext('
Ft2'
Ft3'
Ft4'
Ft5'
Ff+Fw'
zoomon;
[x,y]=ginput
(1);
zoomoff;
disp('
汽车最高车速='
disp(x);
km/h'
汽车最高车速=
99.3006
km/h
(2)求汽车最大爬坡度程序:
n=[600:
Fw1=CDA*ua1.^2/21.15;
Fz1=Ff+Fw1;
Fi1=Ft1-Fz1;
Zoomon;
imax=100*tan(asin(max(Fi1/G)));
汽车最大爬坡度='
disp(imax);
%'
汽车最大爬坡度=
35.2197%
(3)求最大爬坡度相应的附着率和求汽车行驶加速度倒数曲线程序:
clear
Fw2=CDA*ua2.^2/21.15;
Fw3=CDA*ua3.^2/21.15;
Fw4=CDA*ua4.^2/21.15;
Fw5=CDA*ua5.^2/21.15;
deta1=1+(Iw1+Iw2)/(m*r^2)+(If*ig
(1)^2*i0^2*nT)/(m*r^2);
deta2=1+(Iw1+Iw2)/(m*r^2)+(If*ig
(2)^2*i0^2*nT)/(m*r^2);
deta3=1+(Iw1+Iw2)/(m*r^2)+(If*ig(3)^2*i0^2*nT)/(m*r^2);
deta4=1+(Iw1+Iw2)/(m*r^2)+(If*ig(4)^2*i0^2*nT)/(m*r^2);
deta5=1+(Iw1+Iw2)/(m*r^2)+(If*ig(5)^2*i0^2*nT)/(m*r^2);
a1=(Ft1-Ff-Fw1)/(deta1*m);
ad1=1./a1;
a2=(Ft2-Ff-Fw2)/(deta2*m);
ad2=1./a2;
a3=(Ft3-Ff-Fw3)/(deta3*m);
ad3=1./a3;
a4=(Ft4-Ff-Fw4)/(deta4*m);
ad4=1./a4;
a5=(Ft5-Ff-Fw5)/(deta5*m);
ad5=1./a5;
plot(ua1,ad1,ua2,ad2,ua3,ad3,ua4,ad4,ua5,ad5);
axis([099010]);
汽车的加速度倒数曲线'
ua(km/h)'
1/a'
1/a1'
1/a2'
1/a3'
1/a4'
1/a5'
a=max(a1);
af=asin(max(Ft1-Ff-Fw1)/G);
C=tan(af)/(a/L+hg*tan(af)/L);
假设后轮驱动,最大爬坡度相应的附着率='
disp(C);
假设后轮驱动,最大爬坡度相应的附着率=
0.4219
(4)>
>
ig=[5.562.7691.6441.000.793];
u1=0.377*r*nmin./ig/i0;
u2=0.377*r*nmax./ig/i0;
deta=0*ig;
fori=1:
5
deta(i)=1+(Iw1+Iw2)/(m*r^2)+(If*(ig(i))^2*i0^2*nT)/(m*r^2);
end
ua=[6:
0.01:
99];
N=length(ua);
n=0;
Tq=0;
Ft=0;
inv_a=0*ua;
delta=0*ua;
N
k=i;
ifua(i)<
=u2
(2)
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));
delta(i)=0.01*inv_a(i)/3.6;
elseifua(i)<
=u2(3)
n=ua(i)*(ig(3)*i0/r)/0.377;
Ft=Tq*ig(3)*i0*nT/r;
inv_a(i)=(deta(3)*m)/(Ft-Ff-Fw(i));
=u2(4)
n=ua(i)*(ig(4)*i0/r)/0.377;
Ft=Tq*ig(4)*i0*nT/r;
inv_a(i)=(deta(4)*m)/(Ft-Ff-Fw(i));
else
n=ua(i)*(ig(5)*i0/r)/0.377;
Ft=Tq*ig(5)*i0*nT/r;
inv_a(i)=(deta(5)*m)/(Ft-Ff-Fw(i));
end
a=delta(1:
k);
t(i)=sum(a);
plot(t,ua);
axis([0800100]);
汽车2档原地起步换挡加速时间曲线'
时间t(s)'
速度ua(km/h)'
ginput
ans=
25.822370.0737
25.746770.0737
所以汽车2档原地起步换挡加速行驶至70km/h的加速时间约为25.8s
2.7已知货车装用汽油发动机的负荷特性与万有特性。
负荷特性曲线的拟合公式为:
其中,b为燃油消耗率[g/(kW?
h)];
Pe为发动机净功率(kW);
拟合式中的系数随转速n变化。
怠速油耗
(怠速转速400r/min)。
计算与绘制题1.3中货车的
1)汽车功率平衡图。
2)最高档与次高档的等速百公里油耗曲线。
或利用计算机求货车按JB3352-83规定的六工况循环行驶的百公里油耗。
计算中确定燃油消耗值b时,若发动机转速与负荷特性中给定的转速不相等,可由相邻转速的两根曲线用插值法求得。
(1)汽车功率平衡图程序:
ig=[5.562.7691.6441.000.793];
Pe1=Tq.*ig
(1)*i0.*ua1./(3600*r);
Pe2=Tq.*ig
(2)*i0.*ua2./(3600*r);
Pe3=Tq.*ig(3)*i0.*ua3./(3600*r);
Pe4=Tq.*ig(4)*i0.*ua4./(3600*r);
Pe5=Tq.*ig(5)*i0.*ua5./(3600*r);
0.35:
119];
Pf=Ff*ua/3600;
Pw=Fw.*ua/3600;
Pe0=(Pf+Pw)./nT;
Pe=max(Pe1);
plot(ua1,Pe1,ua2,Pe2,ua3,Pe3,ua4,Pe4,ua5,Pe5,ua,Pe0,ua,Pe);
axis([01190100]);
汽车功率平衡图'
Pe(kw)'
1'
2'
3'
4'
5'
(Pf+Pw)/et'
Pe'
(2)最高档与次高档的等速百公里油耗曲线程序:
clear
n=600:
1:
4000;
ig=[5.562.7691.6441.000.793];
n0=[8151207161420122603300634033804];
B00=[1326.81354.71284.41122.91141.01051.21233.91129.7];
B10=[-416.46-303.98-189.75-121.59-98.893-73.714-84.478-45.291];
B20=[72.37936.65714.5247.00354.47632.85932.97880.71113];
B30=[-5.8629-2.0553-0.51184-0.18517-0.091077-0.05138-0.047449-0.00075215];
B40=[0.177680.0430720.00681640.00185550.000689060.000350320.00028230-0.000038568];
B0=spline(n0,B00,n);
B1=spline(n0,B10,n);
B2=spline(n0,B20,n);
B3=spline(n0,B30,n);
B4=spline(n0,B40,n);
Fz4=Ff+CDA*(ua4.^2)/21.15;
Fz5=Ff+CDA*(ua5.^2)/21.15;
Pe4=Fz4.*ua4./(nT*3.6*1000);
Pe5=Fz5.*ua5./(nT*3.6*1000);
3401
b4(i)=B0(i)+B1(i)*Pe4(i)+B2(i)*Pe4(i).^2+B3(i)*Pe4(i).^3+B4(i)*Pe4(i).^4;
b5(i)=B0(i)+B1(i)*Pe5(i)+B2(i)*Pe5(i).^2+B3(i)*Pe5(i).^3+B4(i)*Pe5(i).^4;
pg=7.0;
Q4=Pe4.*b4./(1.02.*ua4.*pg);
Q5=Pe5.*b5./(1.02.*ua5.*pg);
plot(ua4,Q4,ua5,Q5);
axis([01001030]);
最高档与次高档等速百公里油耗曲线'
百公里油耗(L/100km)'
3.1改变1.3题中轻型货车的主减速器传动比,做出
为5.17、5.43、5.83、6.17、6.33时的燃油经济性—加速时间曲线,讨论不同
值对汽车性能的影响。
主程序:
i0=[5.17,5.43,5.83,6.17,6.33];
%输入主传动比的数据
y(i)=jiasushijian(i0(i));
%求加速时间
y;
b(i)=youhao(i0(i));
%求对应i0的六工况百公里油耗
b;
plot(b,y,'
+r'
)
holdon
b1=linspace(b
(1),b(5),100);
y1=spline(b,y,b1);
%三次样条插值
plot(b1,y1);
%绘制燃油经济性-加速时间曲线
燃油经济性—加速时间曲线'
加速时间s'
i0=5.17'
i0=5.43'
i0=5.83'
i0=6.17'
i0=6.33'
子程序:
(1)functiony=jiasushijian(i0)%求加速时间的处理函数
n1=linspace(0,5000);
%先求各个档位的驱动力
yita=0.85;
G=(3880)*9.8;
ig=[6.09,3.09,1.71,1.00];
%i0=5.83
4%i为档数
uamax(i)=chesu(nmax,r,ig(i),i0);
%计算各个档位的最大速度与最小速度
uamin(i)=chesu(nmin,r,ig(i),i0);
ua(i,:
)=linspace(uamin(i),uamax(i),100);
n(i,:
)=zhuansu(ua(i,:
),r,ig(i),i0);
%计算各个档位的转速范围
Ttq(i,:
)=zhuanju(n(i,:
));
%求出各档位的转矩范围
Ft(i,:
)=qudongli(Ttq(i,:
),ig(i),i0,yita,r);
%求出驱动力
F(i,:
)=f*G+CDA*(ua(i,:
).^2)/21.15;
%求出滚动阻力和空气阻力的和
delta(i,:
)=1+(1.798+3.598+0.218*(ig(i)^2)*(i0^2)*yita)/(3880*r^2);
%求转动质量换算系数
a(i,:
)=1./(delta(i,:
).*3880./(Ft(i,:
)-F(i,:
)));
%求出加速度
F2(i,:
)=Ft(i,:
%下面分各个档位进行积分,求出加速时间
temp1(1,:
)=ua(2,:
)/3.6;
temp1(2,:
)=1./a(2,:
n1=1;
forj1=1:
100
ifua(3,j1)>
max(ua(2,:
))&
&
ua(3,j1)<
=70
temp2(1,n1)=ua(3,j1)/3.6;
temp2(2,n1)=1./a(3,j1);
n1=n1+1;
n2=1;
ifua(4,j1)>
max(ua(3,:
ua(4,j1)<
=70;
temp3(1,n2)=ua(4,j1)/3.6;
temp3(2,n2)=1./a(4,j1);
n2=n2+1;
y=temp1(1,1)*temp1(2,1)+qiuji(temp1(1,:
),temp1(2,:
))+qiuji(temp2(1,:
),temp2(2,:
))+qiuji(temp3(1,:
),temp3(2,:
(2)functionua=chesu(n,r,ig,i0);
%由转速计算车速
ua=0.377*r.*n/(ig*i0);
(3)functionn=zhuansu(ua,r,ig,i0);
%求转速
n=ig*i0.*ua./(0.377*r);
(4)functiony=zhuanju(n);
%求转矩函数
y=-19.313+295.27.*(n./1000)-165.44.*(n./1000).^2+40.874.*(n./1000).^3-3.8445.*(n./1000).^4;
(5)functiony=qudongli(Ttq,ig,i0,yita,r);
%求驱动力函数
y=(ig*i0*yita.*Ttq)/r;
(6)functionp=qiuji(x0,y0)%求积分函数
n0=size(x0);
n=n0
(2);
x=linspace(x0
(1),x0(n),200);
y=spline(x0,y0,x);
%插值
%figure;
plot(x,y);
p=trapz(x,y);
(7)%求不同i0下的六工况油耗
functionb=youhao(i0);
globalfGCDAyitamrIfIw1Iw2pgB0B1B2B3B4n%声明全局变量
ig=[6.09
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