《汽车整车性能计算分解》由会员分享，可在线阅读，更多相关《汽车整车性能计算分解（14页珍藏版）》请在金锄头文库上搜索。
1、6 汽车总体性能计算6.1 汽车动力性计算6.1.1 汽车各档车速计算 各挡车速的计算公式如下：rnu 0.377 (km/h)(61)a i ig0式中r汽车滚动半径，r=0.279m；n发动机转速(r/min)；i汽车变速器的传动比，i =3.17； i =2.158； i =1.469； i =1；gg1g 2g3g4i主减速器的传动比，i =5.01。00代入相关参数所得结果见表6 1 。表61 汽车各档车速n(r/min)Ua1(km/h)Ua2(km/h)Ua(km/h)Ua4(km/h)10006.622919.7287414.2917720.9946112007.9474911
2、.6744817.1501225.1935314009.2720713.6202320.0084829.39246160010.5966515.5659822.8668333.59138180011.9212317.5117225.7251937.79030200013.2458119.4574728.5835441.98922220014.5703921.4032231.4418946.18814240015.8949723.3489634.3002550.38707260017.2195525.2947137.1586054.58599280018.5441427.2404640.0169
3、658.78491300019.8687229.1862142.8753162.98383320021.1933031.1319545.7336767.18275340022.5178833.0777048.5920271.38168360023.8424635.0234551.4503775.58060380025.1670436.9691954.3087379.77952400026.4916238.9149457.1670883.97844420027.8162040.8606960.0254488.17737440029.1407842.8064462.8837992.37629460
4、030.4653744.7521865.7421496.57521480031.7899546.6979368.60050100.77413500033.1145348.6436871.45885104.973056.1.2 汽车行驶阻力计算汽车行驶阻力包括：滚动阻力、空气阻力、加速阻力和爬坡阻力。1)滚动阻力滚动阻力计算公式：F= Gf (N) (6-2)f式中 G汽车重力,G=14250N ；f滚动阻力系数,f=0.015。2)空气阻力空气阻力计算公式：F = CDAua(N)(6-3)w 21.25式中C 汽车的空气阻力系数,C=0.52；D DA汽车的迎风面积A=2.726m2；U汽车
5、各档车速(km/h)。a代入相关参数有：2.726 x 0.52 x u 2a21.25所以，汽车的行驶阻力C Au 2Da21.25二 14250 x 0.015 +2.726x0.52xu 2a21.25所得结果见表6-2 。表6-2汽车各档行驶阻力(Ff+Fw)l(Ff+Fw)2(Ff+Fw)3(Ff+Fw)4216.67595220.06369227.37518243.15261217.96337222.84171233.37026256.08976219.48487226.12483240.45536271.37912221.24044229.91304248.63047289.02
6、069223.23009234.20635257.89559309.01446225.45381239.00475268.25073331.36045227.91161244.30824279.69588356.05864230.60349250.11684292.23105383.10905233.52944256.43052305.85623412.51166236.68947263.24930320.57143444.26648240.08358270.57318336.37664478.37351243.71176278.40215353.27187514.83275247.57402
7、286.73622371.25711553.64420251.67035295.57538390.33236594.80785256.00077304.91964410.49763638.32372260.56525314.76899431.75292684.19180265.36382325.12344454.09822732.41208270.39646335.98298477.53353782.98457275.66317347.34761502.05886835.90927281.16396359.21734527.67420891.18619286.89883371.59217554
8、.37956948.815316.1.3 汽车驱动力计算发动机转矩的拟合公式：n n n n T = 67.11731x （一 ） -19.05015 x （一 ）2 +1.88322（）3 0.03392（ ）4q1000100010001000（6-4）汽车驱动力计算公式：rri Til 耳/、zF = g0 T(N)(6-5)tr式中r汽车行驶时的滚动半径,r=0.279m；n发动机曲轴转速(r/min)；i 汽车变速器各挡传动比；gn 传动系效率，n =89.376%；TTi 0汽车主减速器传动比。各档驱动力的计算结果见表6-3。表6-3汽车的各档驱动力FtlFtllFtlllFtW2
9、539.554151728.819511176.84702801.121182863.938231949.646281327.16885903.450543137.181732135.658731453.79179989.647233363.452842289.694391558.647391061.026133546.853472414.545681643.636521118.881223691.419282512.959871710.629311164.485583801.119632587.639171761.465221199.091373879.857642641.240631797
10、.952961223.929863931.470162676.376221821.870561240.211413959.727772695.612781834.965331249.125483968.334762701.472061838.953871251.840623960.929202696.430671835.522081249.504483941.082842682.920121826.325141243.243803912.301212663.326821812.987531234.164423878. 023532639.992041797.103021223.35127384
11、1.622782615.211981780.234661211.868393806.405672591.237681763.914801200.758893775.612632570.275101749.645101191.044993752.417832554.485071738.896461183.728023739.929182545.983331733.109141179.788383741.188302546.840491733.692621180.185586.1.4汽车驱动力-行驶阻力平衡图及最高车速的确定汽车稳速行驶时驱动力、行驶阻力平衡。即： F = F + F(N)tf w
12、(6-6)驱动力行驶阻力平衡图见图6-1。车連Ckn/h)(=二匠空lr二IKT冷图6-1汽车驱动力-行驶阻力平衡图行驶阻力曲线(Ff+Fw-Ua)与四档驱动力曲线(Ft W-Ua)的交点所对应的车速即为汽车的最高行驶车速。由图4-1知汽车的最高车速为：109km/h。设计误差109 -105 为：9-X100% =3.8%三5%，因此满足要求。1056.1.5 汽车加速能力计算1）加速度的计算a = dU =丄Ft-（F + F ）（6-7）dt 5 mf w式中a汽车各挡加速度（m/s2）；5 汽车旋转质量转换系数；F驱动力（N）；tF 风阻力（N）;Wm汽车质量（kg）。并有：5= 1
13、+ 5 i 2 +5（6-8）1 g 2式中 i 变速器的速比g1 I i 2n55 =i T，其中I为飞轮转动惯量，5 =0.04；11 m r 2f11 VI5 5 = w，其中I为车轮转动惯量，5 =0.03。22 m r 2w2计算结果如表6-4 。表6-4 汽车旋转质量换算系数ig3.172.1581.469151.43191.216281.116321.07将表6-4数值带入式6-7中便可求出汽车各档下的加速度，所得结果见表6-5和图6-2。表6-5 汽车各档加速度Ua1Ua2Ua3Ua4a1a2a3a46.622919.7287414.2917720.994611.138410.870500.596870.365947.9474911.6744817.1501225.193531.296760.996310.687600.424579.2720713.6202320.0084829.392461.429921.101740.762740
