汽车转向机构模拟机械原理课程设计

1、一、工作原理汽车机械转向系是由转向操纵机构、转向器和转向传动机构三大部分组成。根据转向器位置和转向轮悬架类型不同，转向传动机构的组成和布置分为与非独立悬架配用的转向传动机构和与独立悬架配用的转向传动机构。这里讨论的是与非独立悬架配用的转向传动机构。 转向传动机构是将转向器输出的力和运动传给转向桥两侧的转向节，使两侧转向轮偏转，并使两转向轮偏转按一定的关系变化，以保证汽车转向时车轮与地面的相对滑动尽可能小。为了避免汽车转向时产生的路面对汽车行驶的附加阻力和轮胎磨损太快，要求转向系在汽车转向时， 所有车轮均做纯滚动而不产生侧向滑移，图 1 中两侧车轮偏转角 和 的理想关系为：cot =cot +B

2、/LB两侧主销轴线与地面相交点之间的距离L汽车轴距因此转向传动机构转向梯形的几何参数需要优化确定，但是，至今所有的汽车的转向梯形都只能设计得在一定的车轮偏转角围，接近于理想关系。为了模拟的方便，转向机构简化为图5.1 所示，由车轮、等腰梯形机构（包括左、右梯形臂、机架、转向横拉杆） 、转向节臂、转向直拉杆、方向盘等组成。图 1（名词解释）非独立悬架：非独立悬架是相对与独立悬架（individual wheel suspension）的车轮结构。非独立悬架的结构特点是两侧车轮由一根整体式车架相连，车轮连同车桥一起通过弹性悬架悬挂在车架或车身的下面。非独立悬架具有结构简单、成本低、强度高、保养容易

3、、行车中前轮定位变化小的优点，但由于其舒适性及操纵稳定性都较差，在现代轿车中基本上已不再使用，多用在货车和大客车上。非独立悬架与独立悬架的比较：二、四杆机构的设计通过图 1 我们可以知道， 非独立悬架配用的转向传动机构是一个绞接四杆机构。汽车直线行驶时，我们不妨称之为“原始位置”。为了使左右转向有相同的性质，这个四杆机构在原始位置是必须为对称机构。又要满足 cot =cot +B/L，只能是等腰梯形机构。不难理解，车轮转角即为梯形臂从原始位置绕机架转动的转角。随意选取一款可能使用非独立悬架的汽车：解放牌 CA1091PK2LA95型平头长轴距载货汽车前轮距 :1800 ( 毫米 )轴距 :43

4、60 ( 毫米 )轮胎规格 :9.00-20,8.25-201 英寸 = 2.539999918厘米 ( 公分 ) 。即： L=4360mm； B 近似等于 1800-9*2.539999918*10=1571.400mmB/L=0.360cot =cot +B/L满足以上要求的一组值（汽车转向轮的最大转角通常为外轮2535°，轮 3545°）：外轮转角最大值 =30°轮转角最大值 =36.09 °一、设计在 Pro/E 的帮助下获得一组合适且满足要求的四杆机构。由于设计者能力有限，不能设计一套绝对满足cot =cot +B/L 的四杆机构，只能设计达到

5、最大转角时满足cot =cot +B/L。得到示意图：机架 L=1571.4连架杆 L1=200连杆 L2=1473.99连架杆即为梯形臂，连杆即为转向横拉杆。二、检验在 Pro/E 中分别定外转角 20°、10°，检验转角。如图：制表： 角（外转角） 角（转角）理想值（度）实际值（度）理想值（度）实际值（度）101010.6610.50202022.7322.23303036.0936.09从上表中可以看出转角的实际值与理想值偏差在一位小数，此设计方案可行。三、设计结果机架 L=1571.4连架杆 L1=200连杆 L2=1473.99 角（外转角）最值30°三

6、、各构件的设计及零件图制作一、节臂（左梯形臂）完成二、梯形臂完成三、机架放大图完成四、连杆完成四、装配机构一、装配机架在 Pro/E 中新建组件文件。插入机架，选固定的约束二、装配节臂插入节臂。选销钉约束（A5与 A3）再选择机架和节臂的两断面对齐。完成后为三、装配梯形臂A4 与 A4销钉连接再取端面对齐。完成后为四、装配连杆插入连杆。 A4与 A3 销钉连接再取两断面对齐。完成后得点右键添加集。 A3与 A6销钉连接，同时断面对齐。完成后为五、运动分析节臂与机架连接的销钉处设置一个伺服电机，设置轮廓，规选“位置”，“模”选常数“-75.91 ”，点确定。 打开分析定义， 运行获得汽车直行时传

7、动机构位置，如图重新编辑定义伺服电机，使其反向；设置轮廓，规选“速度”，“模”选常数“ 10”，点确定。打开分析定义，时间设置为3，这样最大外转角即为30 度。点运行。运行结果为左转弯最大位置，如图点击测量结果。新建测量1，以节臂与连杆销钉连接的轴线为测量点，类型选位置，评估方法选每个时间步长。类似地新建测量2，唯一不同在于测量点选取梯形臂与连杆销钉连接的轴线。分别出图分别点文件选输出Excel 。图表如下图角（外转角）AnalysisDefinition2:measure1 (度)11.59012689-8.40987311100.511.522.533.5-28.40987311量测 -4

8、8.40987311-68.40987311-88.40987311-108.4098731时间( 秒)角（转角）AnalysisDefinition2:measure2 (度)82.3093467777.3093467772.3093467767.30934677量 62.30934677测 57.30934677 52.3093467747.3093467742.3093467737.3093467700.511.522.533.5时间( 秒)角的 Excel 复制到角 Excel 里，再加入理想值， 以方便对比。 结果如下表角（外转角）角（转角）时间理想转时间测量理想值测量理想转角理想值

9、(秒)角(秒)0-75.91030-75.91075.90033075.910.02-76.12350.2-76.110.0275.68710.20025275.709750.04-76.33680.4-76.310.0475.473290.4010080.06-76.550.6-76.510.0675.25910.602270.08-76.76330.8-76.710.0875.044510.8040410.1-76.97661-76.910.174.829531.0063220.12-77.18981.2-77.110.1274.614161.2091150.14-77.40311.4-7

10、7.310.1474.398391.4124220.16-77.61651.6-77.510.1674.182231.6162440.18-77.82981.8-77.710.1873.965671.8205830.2-78.04322-77.910.273.74872.0254420.22-78.25652.2-78.110.2273.531342.2308210.24-78.46992.4-78.310.2473.313572.4367230.26-78.68332.6-78.510.2673.095392.6431490.28-78.89672.8-78.710.2872.876812.

11、8501010.3-79.11023-78.910.372.657813.057580.32-79.32363.2-79.110.3272.438413.2655890.34-79.53713.4-79.310.3472.218593.4741280.36-79.75063.6-79.510.3671.998353.68320.38-79.96413.8-79.710.3871.77773.8928060.4-80.17774-79.910.471.556634.1029470.42-80.39124.2-80.110.4271.335134.3136250.44-80.60484.4-80.

12、310.4471.113214.5248410.46-80.81844.6-80.510.4670.890864.73659875.5089975.3077375.1059674.9036874.7008874.4975874.2937674.0894273.8845673.6791873.4732873.2668573.059972.8524272.6444172.4358772.226872.0171971.8070571.5963871.3851671.17340.48-81.0324.8-80.710.4870.668084.9488960.5-81.24575-80.910.570.

13、444875.1617360.52-81.45935.2-81.110.5270.221235.3751210.54-81.6735.4-81.310.5469.997155.5890520.56-81.88675.6-81.510.5669.772635.8035290.58-82.10055.8-81.710.5869.547676.0185550.6-82.31436-81.910.669.322266.234130.62-82.5286.2-82.110.6269.096416.4502560.64-82.74196.4-82.310.6468.870116.6669340.66-82

14、.95576.6-82.510.6668.643356.8841650.68-83.16966.8-82.710.6868.416147.101950.7-83.38357-82.910.768.188477.3202920.72-83.59747.2-83.110.7267.960347.5391890.74-83.81147.4-83.310.7467.731747.7586440.76-84.02547.6-83.510.7667.502677.9786580.78-84.23947.8-83.710.7867.273148.1992320.8-84.45348-83.910.867.0

15、43138.4203670.82-84.66758.2-84.110.8266.812648.6420630.84-84.88168.4-84.310.8466.581678.8643210.86-85.09588.6-84.510.8666.350229.0871430.88-85.30998.8-84.710.8866.118289.3105290.9-85.52419-84.910.965.885849.53448170.961170.7482670.5348870.3209570.1064769.8914569.6758769.4597469.2430769.0258468.80805

16、68.5897168.3708168.1513667.9313467.7107767.4896367.2679467.0456866.8228666.5994766.375520.92-85.73849.2-85.110.9265.652919.7589980.94-85.95279.4-85.310.9465.419499.9840810.96-86.1679.6-85.510.9665.1855610.209730.98-86.38139.8-85.710.9864.9511210.435951-86.595710-85.91164.7161710.662741.02-86.810210.

17、2-86.111.0264.4807110.890091.04-87.024610.4-86.311.0464.2447311.118021.06-87.239110.6-86.511.0664.0082211.346511.08-87.453710.8-86.711.0863.7711911.575581.1-87.668211-86.911.163.5336311.805221.12-87.882911.2-87.111.1263.2955212.035421.14-88.097511.4-87.311.1463.0568812.26621.16-88.312211.6-87.511.16

18、62.817712.497551.18-88.52711.8-87.711.1862.5779612.729481.2-88.741812-87.911.262.3376712.961971.22-88.956612.2-88.111.2262.0968213.195041.24-89.171512.4-88.311.2461.855413.428681.26-89.386412.6-88.511.2661.6134113.662891.28-89.601412.8-88.711.2861.3708513.897671.3-89.816413-88.911.361.127714.133031.

19、32-90.031513.2-89.111.3260.8839714.368961.34-90.246613.4-89.311.3460.6396514.6054666.15165.9259265.7002765.4740565.2472665.0199164.7919864.5634964.3344264.1047863.8745863.643863.4124563.1805262.9480362.7149662.4813262.2471162.0123361.7769761.5410461.304541.36-90.461813.6-89.511.3660.3947314.842531.3

20、8-90.67713.8-89.711.3860.1492115.080171.4-90.892314-89.911.459.9030715.318391.42-91.107714.2-90.111.4259.6563215.557171.44-91.32314.4-90.311.4459.4089515.796531.46-91.538514.6-90.511.4659.1609516.036451.48-91.75414.8-90.711.4858.9123216.276951.5-91.969515-90.911.558.6630416.518011.52-92.185115.2-91.

21、111.5258.4131216.759641.54-92.400815.4-91.311.5458.1625417.001841.56-92.616515.6-91.511.5657.911317.24461.58-92.832315.8-91.711.5857.6593917.487941.6-93.048216-91.911.657.406817.731831.62-93.264116.2-92.111.6257.1535317.976291.64-93.480116.4-92.311.6456.8995618.221311.66-93.696116.6-92.511.6656.6449

22、18.46691.68-93.912216.8-92.711.6856.3895318.713041.7-94.128417-92.911.756.1334418.959751.72-94.344617.2-93.111.7255.8766319.207011.74-94.56117.4-93.311.7455.6190819.454831.76-94.777317.6-93.511.7655.3607919.703211.78-94.993817.8-93.711.7855.1017519.9521461.0674760.8298360.5916160.3528360.1134759.873

23、5559.6330559.3919959.1503658.9081658.665458.4220658.1781757.9337157.6886957.443157.1969656.9502556.7029956.4551756.2067955.957861.8-95.210318-93.911.854.8419520.201621.82-95.426918.2-94.111.8254.5813820.451651.84-95.643618.4-94.311.8454.3200320.702241.86-95.860418.6-94.511.8654.0578920.953371.88-96.

24、077218.8-94.711.8853.7949521.205051.9-96.294119-94.911.953.531221.457271.92-96.511119.2-95.111.9253.2666321.710031.94-96.728219.4-95.311.9453.0012221.963341.96-96.945419.6-95.511.9652.7349822.217181.98-97.162719.8-95.711.9852.4678822.471562-97.3820-95.91252.1999122.726482.02-97.597420.2-96.112.0251.

25、9310622.981922.04-97.81520.4-96.312.0451.6613323.23792.06-98.032620.6-96.512.0651.3906923.49442.08-98.250320.8-96.712.0851.1191423.751432.1-98.468121-96.912.150.8466524.008992.12-98.68621.2-97.112.1250.5732224.267062.14-98.90421.4-97.312.1450.2988424.525652.16-99.122121.6-97.512.1650.0234824.784752.

26、18-99.340321.8-97.712.1849.7471425.044372.2-99.558722-97.912.249.4697925.30452.22-99.777122.2-98.112.2249.1914325.5651355.7083855.4583555.2077654.9566354.7049554.4527354.1999753.9466653.6928253.4384453.1835252.9280852.672152.415652.1585751.9010151.6429451.3843551.1252550.8656350.605550.344872.24-99.

27、995622.4-98.312.2448.9120425.826262.26-100.21422.6-98.512.2648.6315926.08792.28-100.43322.8-98.712.2848.3500826.350032.3-100.65223-98.912.348.0674826.612662.32-100.87123.2-99.112.3247.7837926.875782.34-101.0923.4-99.312.3447.4989727.139382.36-101.30923.6-99.512.3647.2130127.403472.38-101.52923.8-99.

28、712.3846.925927.668042.4-101.74824-99.912.446.637627.933092.42-101.96824.2-100.112.4246.3481128.198612.44-102.18824.4-100.312.4446.057428.46462.46-102.40724.6-100.512.4645.7654428.731052.48-102.62824.8-100.712.4845.4722228.997972.5-102.84825-100.912.545.1777129.265352.52-103.06825.2-101.112.5244.881

29、8929.533182.54-103.28925.4-101.312.5444.5847329.801462.56-103.50925.6-101.512.5644.2862130.070192.58-103.7325.8-101.712.5843.986330.339362.6-103.95126-101.912.643.6849730.608972.62-104.17226.2-102.112.6243.382230.879012.64-104.39326.4-102.312.6443.0779531.149482.66-104.61526.6-102.512.6642.772231.42

30、03750.0837449.822149.5599749.2973449.0342248.7706248.5065348.2419647.9769147.7113947.445447.1789546.9120346.6446546.3768246.1085445.8398145.5706445.3010345.0309944.7605244.489632.68-104.83626.8-102.712.6842.4649231.691692.7-105.05827-102.912.742.1560731.963422.72-105.2827.2-103.112.7241.8456232.2355

31、62.74-105.50227.4-103.312.7441.5335332.508112.76-105.72527.6-103.512.7641.2197732.781062.78-105.94727.8-103.712.7840.9043133.05442.8-106.1728-103.912.840.587133.328142.82-106.39328.2-104.112.8240.268133.602262.84-106.61628.4-104.312.8439.9472733.876772.86-106.8428.6-104.512.8639.6245834.151652.88-10

32、7.06328.8-104.712.8839.2999734.42692.9-107.28729-104.912.938.973434.702522.92-107.51129.2-105.112.9238.6448134.97852.94-107.73529.4-105.312.9438.3141735.254832.96-107.9629.6-105.512.9637.9814235.531522.98-108.18529.8-105.712.9837.6464935.808553-108.4130-105.91337.3093536.08591测量值与理想值联合制成图表，角与角分别为44.

33、2183143.9465843.6744443.4018943.1289442.855642.5818642.3077442.0332341.7583541.483141.2074840.931540.6551740.3784840.1014539.824090 061.-200-40角转-60-80-100-12080706050角转 40302010004812.0023.024.084.065.046.07.08.048.069.089.0角284662844628124. 7902. 578. . .1.2.1111122222时间角2644826148268412. 5689. 23

34、56. 9. .1.2.2 .11111122222时间测量理想值测量理想值由于节臂匀速转动， 所以上面两表中的横坐标也可看作是汽车的转角。随着汽车转角的增大，实际值与理想值的偏差增大。 角与角的最大偏差分别2.5 °和 2.53155 °。偏差的产生， 设计的优化不够是主要原因。此外，所用到的方法和手段也是产生偏差的原因。 比如，四连杆的设计时得出的连杆长1473.99 是 Pro/E 自动省去后面的数得出的近似值。再如，轮转角最大值=36.09 °也是取的近似值，而设计四连杆时利用了这个值，更精确的值是36.08591 °。需要注意的是，近似值的影响可能使偏差增大也可能使之减小，是不可知的。六、总结在此次设计过程中， 我深刻体会到数学功底对工程设计的重要性。要成为一流的工程设计师，掌握高级数学知识和能力是必不可少的。在教材汽车设计里面，非独立悬架配用的转向传动机构的设计，运用数学方法获得优化的设计结果。而我却很难看懂，我的设计也就没有了这么好的参考。同时我也认识到，路不只有一条，我们可以在计算机的帮助下， 解决一些被自己数学能力限制而不能完成的工作。随着工程辅助软件的不断发展，计算机解决工程问题的能力不断强大，但是我想，学习高级数学、提