汽车理论大作业

1、汽车理论大作业计算任务书题目：第一题 汽车动力性能的计算确定一轻型货车的动力性能（货车装用5档变速器）1. 绘制汽车驱动力与行驶阻力平衡图。2. 求汽车最高时速，最大爬坡度及克服该爬坡度时对应的附着率。3. 绘制汽车行驶加速度倒数曲线，用图解积分法求汽车用2档起步加速至70km/h的车速-时间曲线，或者用计算机求汽车用2档起步加速至70km/h的加速时间。轻型货车的有关数据：汽油发动机使用外特性的Tq-n曲线的拟合公式位：Tq=-19.313+295.27(n/1000)-165.44(n/1000)2+40.874(n/1000)3-3.8455(n/1000)4式中，Tq为发动机的转矩(N

2、*m);n位发动机的转速(r/min)。发动机的最低转速nmin=600r/min,最高转速nmax=4000r/min装备质量 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 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主减速器传动比 i0=5.83飞轮转动惯量 If=0.218kg*m22前轮转动惯量 Iw1=1.798kg*m24后轮转动惯量 Iw2=3.598kg*m2变速器传动比 Ig（数据如下表）1档2档3档4档5档4档变速器6.033.031.671-轴距 L=3.2m质心至前轴距离(满载)

3、 a=1.947m质心高(满载) hg=0.9m第二题：第三题：计算1. 确定一轻型货车的动力性能1.1绘制汽车驱动力与行驶阻力平衡图1.1.1发动机转矩1.汽油发动机使用外特性的Tq-n曲线拟合公式为：Tq=-19.313+295.27(n/1000)-165.44(n/1000)2+40.874(n/1000)3-3.8455(n/1000)42.式中，Tq为发动机的转矩(N*m);n位发动机的转速(r/min)。发动机的最低转速nmin=600r/min,最高转速nmax=4000r/min2. 发动机的转矩：将转速带入汽油发动机使用外特性的Tq-n曲线拟合公式，取转速间隔为100r/m

4、in，得发动机转矩表如下：表1.1发动机转矩表n(r/min)Tq(N*m)n(r/min)Tq(N*m)n(r/min)Tq(N*m)600106.62111800174.16653000169.7305700119.40711900174.71453100168.7753800130.37422000174.9473200167.6796900139.69842100174.92953300166.3981000147.54652200174.7183400164.87591100154.07622300174.35953500163.04951200159.43572400173.891

5、53600160.84561300163.76432500173.3425370015819182600172.73163800154.9671500169.8392700172.06883900151.11600171.81722800171.35494000146.4711700173.22872900170.5814表1.1.1 发动机转矩表1.1.2 发动机在各档位下的驱动力驱动力计算公式：式中i0=5.83, r=0.367, 4档变速箱传动比ig(数据如下)1档2档3档4档4档变速器6.033.031.671表1.1.2 各档位传动比将个转速下发动机转矩带

6、入驱动力计算公式可得各档位不同转速下的发动机驱动力发动机驱动力表转速驱动力F（N）转速(r/min)1档2档3档4档6008681.2454362.2182404.2591439.6767009722.2964885.3332692.5761612.32180010615.2545334.0332939.8801760.40790011374.4435715.5163150.1361886.309100012013.4496036.6083327.1081992.28110012545.1016303.7573474.3482080.448120012981.4866523.0353595.2

7、042152.817130013333.9216700.1303692.8112211.264140013612.9966840.3613770.1002257.545150013828.5336948.6663829.7932293.289160013989.67029.63874.42320170014104.5327087.3523906.2302339.06180014180.8897125.7203927.3772351.723190014225.5007148.1373939.7432359.121200014244.4347157.6513944.9762362.26121001

8、4243.0107156.9353944.5822362.025220014225.7957148.2853939.81423595977133.6133931.7282354.328240014158.4947114.4673921.1752348.009250014113.7947092.0063908.7952340.596260014064.0527067.0113895.0192332.347270014010.0907039.8963880.0752323.398280013951.9677010.6903863.9782313.759290013888.

9、9836979.0413846.5342303.314300013819.6996944.2273827.3462291.824310013741.9246905.1463805.8062278.926320013652.7116860.3173781.0992264.131330013548.3666807.8863752.2012246.827340013424.4326745.6103717.8772226.274350013275.7216670.8853676.6922201.612360013096.2806580.7183626.9962171.854370012879.3986

10、471.7373566.9312135.887380012617.6376340.2053494.4372092.477390012302.7806181.9943407.2372040.262400011925.8815992.6073302.8561977.758表1.1.3 发动机驱动力表1.1.3 发动机在各档位下的车速不同档位下的车速：Ua=0.377*n*r/(ig*i0)式中i0=5.83, r=0.367, 4档变速箱传动比ig(数据如下)1档2档3档4档4档变速器6.033.031.671表1.1.4发动机驱动力表将各参数带入各档位不同转速对应的车速计算公式可得下表：表1.1

11、.5 各档位不同转速对应车速n(r/min)1档车车速2档车车速3档车车速4档车车速Ua(km/h)Ua(km/h)Ua(km/h)Ua(km/h)6002.3614184.6994558.52655614.239357002.7549875.4826979.94764816.612578003.1485576.2659411.3687418.98589003.5421267.04918212.7898321.3590210003.9356967.83242514.2109323.7322511004.3292668.61566715.6320226.1054712004.7228359.39

12、89117.0531128.478713005.11640510.1821518.474230.8519214005.50997410.9653919.895333.2251515005.90354411.7486421.3163935.5983716006.29711412.5318822.7374837.971617006.69068313.3151224.1585740.3448218007.08425314.0983625.5796742.7180419007.47782214.8816127.0007645.0912720007.87139215.6648528.4218547.46

13、44921008.26496216.4480929.8429549.8377222008.65853117.2313331.2640452.2109423009.05210118.0145832.6851354.5841724009.4456718.7978234.1062256.9573925009.8392419.5810635.5273259.33062260010.2328120.364336.9484161.70384270010.6263821.1475538.369564.07707280011.0199521.9307939.7905966.45029290011.413522

14、2.7140341.2116968.82352300011.8070923.4972742.6327871.19674310012.2006624.2805244.0538773.56997320012.5942325.0637645.4749675.94319330012.987825.84746.8960678.31642340013.3813726.6302448.3171580.68964350013.7749427.4134949.7382483.06286360014.1685128.1967351.1593385.43609370014.5620828.9799752.58043

15、87.80931380014.9556429.7632154.00152903492130.5464655.4226192.55576400015.7427831.329756.8437194.92899表1.1.5 各档位不同转速对应的车速1.1.4 行驶阻力 Ff+Fw汽车行驶方程式Ff=Ff+Fw+Fi+Fj式中Ff-滚动阻力，Fw-空气阻力，Fi-坡度阻力，Fj-加速阻力汽车驱动力-行驶阻力平衡图把汽车行驶中经常遇到的滚动阻力Ff，空气阻力Fw叠加到行驶阻力Ff+Fw=Gf+CD*A/21.15*ua2=mgf+CD*A/21.15*ua2=3880*10*0

16、.013+2.77/21.15*ua2=504.4+2.77/21.15*ua2式中，G-作用于汽车上的重力m-汽车总质量g-重力加速度f-滚动阻力系数CD-空气阻力系数A- 迎风面积(m2)Ua-汽车行驶速度(km/h)1档车速1档驱动力2档车速2档驱动力3档车速3档驱动力4档车速4档驱动力u(km/h)F(N)u(km/h)F(N)u(km/h)F(N)u(km/h)F(N)2.3614188681.2454.6994554362.2188.5265562404.25914.239351439.6762.7549879722.2985.4826974885.3349.9476482692.

17、57716.612571612.3213256.265945334.03211.368742939.87918.98581760.4073.54212611374.447.0491825715.51512.789833150.13521.359021886.3093.93569612013.457.8324256036.60814.210933327.10723.732251992.284.32926612545.18.6156676303.75715.632023474.34826.105472080.4484.72283512981.489.398916523.0

18、3417.053113595.20428.47872152.8175.11640513333.9210.182156700.13118.47423692.81130.851922211.2645.5099741361310.965396840.36219.89533770.133.225152257.5455.90354413828.5311.748646948.66521.316393829.79235.598372293.2896.29711413989.612.531887029.60122.737483874.437.971623206.69068314104.5313.3151270

19、87.35124.158573906.2340.344822339.067.08425314180.8914.098367125.7225.579673927.37742.718042351.7237.47782214225.514.881617148.13727.000763939.73245.091272359.1217.87139214244.4415.664857157.65128.421853944.97647.464492362.2618.26496214243.0116.448097156.93529.842953944.58149.837722362.0258.65853114

20、225.7917.231337148.28431.264043939.81352.210942359.179.05210114196.618.014587133.61432.685133931.72854.584172354.3289.4456714158.4918.797827114.46734.106223921.17556.957392348.0099.8392414113.7919.581067092.00535.527323908.79559.330622340.59610.2328114064.0520.36437067.01236.948413895.0261.703842332

21、.34710.6263814010.0921.147557039.89738.36953880.07564.077072323.39811.0199513951.9721.930797010.68939.790593863.97766.450292313.75911.4135213888.9822.714036979.04141.211693846.53468.823522303.31411.8070913819.723.497276944.22742.632783827.34671.196742291.82412.2006613741.9324.280526905.14644.0538738

22、05.80773.569972278.92612.5942313652.7125.063766860.31845.474963781.09975.943192264.13112.987813548.3625.8476807.88446.896063752.278.316422246.82713.3813713424.4326.630246745.61148.317153717.87880.689642226.27413.7749413275.7227.413496670.88549.738243676.69283.062862201.61214.1685113096.2828.19673658

23、0.71651.159333626.99585.436092171.85414.5620812879.428.979976471.73852.580433566.93187.809312135.88714.9556412617.6329.763216340.20454.001523494.43690.182542092.47715.3492112302.7830.546466181.99455.422613407.23792.555762040.26215.7427811925.8831.32975992.60656.843713302.85594.928991977.758表1.1.6 各档

24、位不同车速对应的驱动力车速u(km/h)Ff+Fw车速u(km/h)Ff+Fw车速u(km/h)Ff+Fw0504.442735.4298841428.5192504.923944757.9565861473.0494506.495546781.531881518.6266509.114948806.1532901565.2518512.78250831.8232921612.92410517.496952858.5409941661.64412523.259654886.3064961711.41314530.0756915.1196981762.22916537.928158944.980

25、61001814.09318546.83460975.88941021867.00420556.7877621007.8461041920.96422567.7891641040.851061975.97124579.8383661074.9021082032.02626592.9352681110.0021102089.12828607.0799701146.1491122147.27830622.2723721183.3451142206.47732638.5125741221.5881162266.72234655.8005761260.8781182328.01636674.13627

26、81301.2171202390.35738693.5196801342.60340713.9508821385.037图1.2 汽车驱动力与阻力平衡图1.2求汽车最高车速，最大爬坡度及克服该坡度时相应的附着率1.2.1汽车最高车速的确定Ua max=0.377*rn/igi0=94.93（km/h）1.2.2汽车最大爬坡度的确定所谓汽车的爬坡度，是指汽车在良好路面上克服Ff+Fw后的余力全部来（即等速）克服坡度阻力是能爬上的坡度，所以du/dt=0。因此，Fi=Ft-(Ff+Fw)一般汽车的最大爬坡度达30%左右，因此利用汽车行驶方程来确定1档及抵挡爬坡能力时，应采用Gsina作为坡度阻力，

27、即为Gsina=Ttq*ig*i0*nT/r-(Gf+CDAu2/21.15)a=arcsin*(Ft-(Ff+Fw)/G)i=tga得到下图表:1档车速1档驱动力Ff+Fwaiu(km/h)F(N)2.3614188681.245505.13030.2123160.2155652.7549879722.298505.39410.2398420.244549325505.69840.2635980.2698773.54212611374.44506.04320.2839120.2917953.93569612013.45506.42870.3011020.310544

28、4.32926612545.1506.85470.3154710.326374.72283512981.48507.32130.3273120.3395245.11640513333.92507.82850.3369070.350265.50997413613508.37620.3445230.3588345.90354413828.53508.96450.3504150.3654996.29711413989.6509.59340.3548210.3705026.69068314104.53510.26290.3579640.374087.08425314180.89510.97290.36

29、00460.3764567.47782214225.5511.72350.3612540.3778367.87139214244.44512.51470.3617540.3784078.26496214243.01513.34650.3616920.3783368.65853114225.79514.21880.3611940.3777669.05210114196.6515.13170.3603640.3768199.4456714158.49516.08520.3592890.3755919.8392414113.79517.07920.3580310.37415710.232811406

30、4.05518.11380.3566340.37256510.6263814010.09519.1890.3551210.37084311.0199513951.97520.30480.3534930.36899211.4135213888.98521.46120.3517310.36699211.8070913819.7522.65810.3497970.36479912.2006613741.93523.89560.347630.36234512.5942313652.71525.17360.3451510.35954312.987813548.36526.49230.3422580.35

31、62813.3813713424.43527.85150.3388320.35242413.7749413275.72529.25130.3347810.34787614.1685113096.28530.69160.3298020.34230314.5620812879.4532.17260.3238590.33567814.9556412617.63533.69410.316710.32774215.3492112302.78535.25610.308140.31827815.7427811925.88536.85880.2979190.307058图1.2.1 1档对应的爬坡度表其中，汽

32、车的最大爬坡度位imax为1档的最大爬坡度，即Imax=0.378336。1.2.3 克服最大坡度时相对应的附着率计算Cw2=(i+1/cosa*1/g*du/dt)/(a/L+hg/L(i+1/cosa*1/g*du/dt)由于是求最大坡度下的附着率，即du/dt=0，所以上式可化简为Cw2=i/(a/L+hg/L*i)式中i=0.378,a=1.947,hg=0.9,L=3.2代入数据的Cw2=0.5291.3 绘制汽车加速度倒数曲线1.3.1绘制汽车加速度倒数曲线=1+1/mIw/r2+1/m*(If*ig2*i02*nT)/r2式中m=3880kg,r=0.367m,If=0.218k

33、g*m2,i0=5.83, T=0.85Iw=Iw1+Iw2=1.798+3.598=5.396kg*m2,4档变速器传动比i0（数据如下表）1档2档3档4档4档变速器6.063.031.671由此可得各档的传动比见下表：1档2档3档4档ig6.063.031.6711.4426811.1181891.0428821.021806表1.2.2 格挡旋转质量转换系数2.由公式du/dt=1/m(Ft-(Ff+Fw)可得1,2,3,4,档加速度1档加速度1档车速1档驱动力Ff+Fwa(m/s2)1/au(km/h)F(N)2.3614188681.245505.13031.4606460.6846

34、292.7549879722.298505.39411.6465810.607319325505.69841.8060510.5536943.54212611374.44506.04321.9416170.5150353.93569612013.45506.42872.0557050.4864514.32926612545.1506.85472.1506080.4649854.72283512981.48507.32132.2284830.4487365.11640513333.92507.82852.2913550.4364235.50997413613508.37

35、622.3411130.4271475.90354413828.53508.96452.3795130.4202546.29711413989.6509.59342.4081750.4152526.69068314104.53510.26292.4285870.4117627.08425314180.89510.97292.4421020.4094837.47782214225.5511.72352.4499380.4081747.87139214244.44512.51472.4531790.4076348.26496214243.01513.34652.4527760.4077018.65

36、853114225.79514.21882.4495440.4082399.05210114196.6515.13172.4441660.4091389.4456714158.49516.08522.4371880.4103099.8392414113.79517.07922.4290240.41168810.2328114064.05518.11382.4199540.41323110.6263814010.09519.1892.4101220.41491711.0199513951.97520.30482.3995380.41674711.4135213888.98521.46122.38

37、8080.41874611.8070913819.7522.65812.3754890.42096612.2006613741.93523.89562.3613730.42348212.5942313652.71525.17362.3452070.42640212.987813548.36526.49232.326330.42986213.3813713424.43527.85152.3039480.43403813.7749413275.72529.25132.277130.43914914.1685113096.28530.69162.2448160.44547114.5620812879

38、.4532.17262.2058060.45334914.9556412617.63533.69412.1587710.46322715.3492112302.78535.25612.1022440.47568215.7427811925.88536.85882.0346250.491491表1.2.3 1档加速度2档加速度2档车速2档驱动力Ff+Fwa(m/s2)1/au(km/h)F(N)4.6994554362.218507.29240.8885241.1254625.4826974885.334508.33691.0088560.9912216.265945334.032509.542

39、11.1119990.8992817.0491825715.515510.9081.1996130.8336027.8324256036.608512.43461.273270.785388.6156676303.757514.12181.3344560.7493699.398916523.034515.96981.3845710.72224510.182156700.131517.97841.4249270.7017910.965396840.362520.14771.4567490.6864611.748646948.665522.47781.4811750.6751412.5318870

40、29.601524.96851.4992560.66699713.315127087.351527.61991.5119560.66139514.098367125.72530.4321.5201510.65782914.881617148.137533.40471.5246330.65589515.664857157.651536.53821.5261040.65526316.448097156.935539.83241.5251790.65566117.231337148.284543.28721.5223890.65686218.014587133.614546.90281.518175

41、0.65868618.797827114.467550.6791.5128910.66098619.581067092.005554.6161.5068060.66365520.36437067.012558.71361.5001010.66662221.147557039.897562.97191.492870.66985121.930797010.689567.39091.4851190.67334722.714036979.041571.97061.4767690.67715423.497276944.227576.7111.4676520.6813624.280526905.14658

42、1.61211.4575150.68609925.063766860.318586.67381.4460150.69155625.8476807.884591.89631.4327260.6979726.630246745.611597.27951.4171320.70565127.413496670.885602.82331.3986310.71498528.196736580.716608.52781.3765330.72646328.979976471.738614.39311.3500620.74070729.763216340.204620.4191.3183560.7585230.

43、546466181.994626.60561.2804640.78096731.32975992.606632.95291.2353490.809488表1.2.3 2档加速度3档加速度3档车速3档驱动力Ff+Fwa(m/s2)1/au(km/h)F(N)8.5265562404.259513.92170.4671672.1405619.9476482692.577517.36020.5375711.8602211.368742939.879521.32760.5977071.6730612.789833150.135525.82390.6485571.54188314.210933327.1

44、07530.84930.6910511.4470715.632023474.348536.40370.7260671.37728317.053113595.204542.4870.7544311.32550218.47423692.811549.09930.7769191.28713519.89533770.1556.24060.7942551.25904121.316393829.792563.91090.8071111.23898622.737483874.4572.11020.8161091.22532624.158573906.23580.83850.8218181.21681425.

45、579673927.377590.09570.8247571.21247927.000763939.732599.8820.8253921.21154628.421853944.976610.19720.8241381.21338829.842953944.581621.04140.8213611.21749231.264043939.813632.41460.8173721.22343432.685133931.728644.31680.8124321.23087234.106223921.175656.7480.8067521.23953835.527323908.795669.70810

46、.800491.24923636.948413895.02683.19730.7937521.2598438.36953880.075697.21540.7865941.27130439.790593863.977711.76250.779021.28366341.211693846.534726.83860.7709841.29704442.632783827.346742.44370.7623851.31167344.053873805.807758.57780.7530751.32788945.474963781.099775.24080.7428511.34616546.8960637

47、52.2792.43290.731461.36712848.317153717.878810.15390.7185981.39159849.738243676.692828.40390.703911.42063651.159333626.995847.18290.6869871.45563152.580433566.931866.49090.6673721.49841654.001523494.436886.32790.6445531.55146355.422613407.237906.69380.617971.61820156.843713302.855927.58880.587011.70

48、3549表1.2.5 3档加速度4档加速度4档车速4档驱动力Ff+Fwa(m/s2)1/au(km/h)F(N)14.239351439.676520.30130.2318954.31228716.612571612.321526.04350.2739943.64971718.98581760.407532.6690.3096743.22919721.359021886.309540.1780.3395372.94518823.732251992.28548.57030.3641492.74612526.105472080.448557.84610.3840492.60383728.47872152.817568.0053