车辆专业课程设计说明
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- 车辆专业课程设计说明目录
1.概述···············································································1
1.1 整车总布置设计的任务··························································2
1.2 设计原则、目标································································2
1.3设计方案的拟定································································2
2.整车型式的选择·····································································3
2.1汽车轴数和驱动形式····························································3
2.2发动机的种类和型式····························································3
2.3车头、驾驶室的型式····························································4
2.4轮胎的选择····································································4
3.汽车主要参数的选择·································································5
3.1主要尺寸参数的选择····························································5
3.1.1轴距L···································································5
3.1.2前轮距B1和后轮距B2····················································5
3.1.3汽车的外廓尺寸···························································6
3.1.4前悬和后悬·························································6
3.2整车质量参数估算······························································7
3.2.1空车状态下整车质量·······················································7
3.2.2汽车的轴荷分配···························································7
3.3主要性能参数的选择····························································7
3.3.1动力性参数······························································9
3.3.2燃料经济性参数··························································10
3.3.3机动性参数······························································10
3.3.4汽车的操纵稳定性参数····················································11
3.3.5行驶平顺性参数··························································11
3.3.6制动性参数······························································12
3.3.7通过性参数·····························································12
4.发动机选型········································································14
4.1 发动机最大功率及其相应转速···········································14
4.2 发动机最大转矩及其相应转速··········································15
4.3 发动机适应性系数φ···························································16
5.轮胎的选择········································································17
6.汽车总布置图的绘制································································18
6.1 搜集和绘制有关总成、部件的外形图··············································18
6.2 基准线的选择及其画法·························································18
6.3 车厢及驾驶室的布置···························································19
6.4 发动机与离合器及变速器的布置·················································20
6.5 转向系、操纵踏板及仪表板的布置················································20
6.6 车身底板的布置·······························································21
6.7 前后悬架的布置·······························································21
6.8 制动系的布置·································································21
6.9 油箱、备胎和行李箱等的布置····················································22
6.10轴荷分配和质心位置的计算····················································22
7.设计小结··········································································23
参考文献·········································································24
汽车总体设计
1.概述
汽车设计的内容包括整车总体设计、总成设计和零件设计。整车总体设计又称为汽车的总布置设计，其任务是使所设计的产品达到设计任务书所规定的整车参数和性能指标的要求，并将这些整车参数和性能指标分解为有关总成的参数和功能。解决人车之间的联系问题属于人机工程设计，它在汽车设计工作中占有极重要的位置。例如：驾驶操作空间尺寸的布置，车内乘客空间尺寸的布置，座椅尺寸参数与特性参数的选择，车身的外观造型与色彩，仪表板的造型及仪表的选型与布置，车身内饰材料与色彩的选择，汽车的驾驶视野，汽车的驾驶性能与乘坐性能等，这些与人的感觉与视觉有直接联系的方方面面，都会对汽车产品的设计质量、品位和市场竞争力产生巨大的影响。
汽车是一个系统，这是基于汽车只有如下属性而具备组成系统的条件：
(1)汽车是由多个要素（子系统及连接零件）组成的整体，每个要素对整体的行为有影响；
(2)组成汽车的各要素对整体行为的影响不是独立的；
(3)汽车的行为不是组成它的任何要素所能具有的。
由此，汽车具备系统的属性，对环境表现出整体性、一辆子系统属性匹配协调的汽车所具备的功能大于组成它的各子系统功能纯粹的、简单的总和、反之，如果子系统的属性因无序而相互干扰，即便是个体性能优良的子系统，其功能也会因相互扼制而抵消，功率循环、轴转向等就是这样的典型例子。
系统论所揭示的系统整体性和系统功能的等级性必然会映射到设计任务中来、用整体性来解释汽车设计的终极目标是整车性能的综合优化，道理是十分显然的、汽车设计任务的等级形态表现为：上位设计任务是确定下位设计任务要实现的目标，下位设计是实现上位设计功能的手段、上、下位体系可从总体设计逐级分至零件设计，总体设计无疑处于这种体系的最上位，设计子系统的全部活动必须在总体设计构建的框架内进行、子系统设计固然重要，但统揽全局、设计子系统组合和相互作用体系规则的总体设计对汽车的性能和质量的影响更加广泛、更为深刻。
1.1 整车总布置设计的任务
(1) 从技术先进性、生产合理性和使用要求出发，正确选择性能指标、质量和主要尺寸参数，提出总体设计方案，为各部件设计提供整车参数和设计要求；
(2) 对各部件进行合理布置和运动校核；
(3) 对整车性能进行计算和控制，保证汽车主要性能指标实现；
(4) 协调好整车与总成之间的匹配关系，配合总成完成布置设计，使整车的性能、可靠性达到设计要求。
1.2 设计原则、目标
(1)汽车的选型应根据汽车型谱、市场需求、产品的技术发展趋势和企业的产品发展规划进行；
(2)选型应在对同类型产品进行深入的市场调查、使用调查、生产工艺调查、样车结构分析与性能分析及全面的技术、进行分析的基础上进行；
(3)应从已有的基础出发，对原有车型和引进的样车进行分析比较，继承优点，消除缺陷，采用已有且成熟可靠的先进技术与结构，开发新车型；
(4)涉及应遵守有关标准、规范、法规、法律，不得侵犯他人专利；
(5)力求零件标准化、部件通用化、产品系列化。
1.3设计方案的拟定
(1)调查研究与初始决策：选定设计目标，并制定产品设计工作及方针原则；
(2)总体方案设计：根据所选定的目标及对开发目标制定的工作方针、设计原则等主导思想提出整车设想；
(3)绘制总布置草图，确定整车主要尺寸、质量参数与性能以及各总成的基本形式；
(4)编写设计任务书；
(5)汽车总布置设计；
(6)总成设计。
2. 整车型式的选择
根据设计原则，目标和用户的需求特点，整车设计人员要提出被开发车型的整车型式方案，主要包括以下几部分：
(1)发动机的种类和型式；
(2)轴数和驱动型式；
(3)车头和驾驶室的型式及与发动机、前轴(轮)的位置关系；
(4)轮胎的选择。
2.1汽车轴数和驱动形式
不同类型的汽车有不同的轴数和驱动型式，这主要根据使用条件、用途、工厂的生产条件、制造成本及公路的轴荷限值等因素进行选择。汽车可以有两轴、三轴、四轴甚至更多的轴数。影响选取轴数的因素主要有汽车的总质量、道路法规对轴载质量的限制和轮胎的负荷能力以及汽车的结构等。最常用的是两轴、后驱动4×2式汽车，其中轿车还可以采用4×2前驱动式结构。对于一般总重小于 19t的汽车，都采用4×2后驱动的布置型式，因为这种汽车结构简单、布置合理、机动性好、成本低、适合于公路使用，是—种典型的、成熟的结构型式。
2.2发动机的种类和型式
至今世界上绝大多数的汽车都是采用往复活塞式内燃机，其中绝大多数的轿车采用汽油机。根据发动机气缸排列形式不同，发动机有直列、水平对置和V型三种。气缸直列式排列具有结构简单、宽度窄、布置方便等优点。但当发动机缸数多时，长度尺寸过长，在汽车上布置困难，因此直列式适用于6缸以下的发动机。此外，直列式还有高度尺寸大的缺点。
根据发动机冷却方式不同，发动机分为水冷与风冷两种。大部分汽车用水冷发动机，因为它具有冷却均匀可靠、散热良好、噪声小和能解决车内供暖问题，以及加大散热器面积后，能较好适应发动机增压后散热的需要等优点。水冷发动机的主要缺点是冷却系结构复杂；使用与维修不方便；冷却性能受环境温度影响较大。选取发动机的冷却方式为水冷。
2.3车头、驾驶室的型式
车头、驾驶室的型式是汽车的最主要的型式之一。其选择主要决定于用户的要求、安全性、维修保养的方便性和生产条件等因素。
2.4轮胎的选择
轮胎的尺寸和型号是进行汽车性能计算和绘制总布置图的重要原始数据之一，选择的依据是车型、使用条件、轮胎的静负荷、轮胎的额定负荷以及汽车的行驶速度。当然还应考虑与动力—传动系参数的匹配以及对整车尺寸参数(例如汽车的最小离地间隙、总高等)的影响。...
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