汽车底盘构造和四大体系详解
车架
一、功用车架是汽车的基体，如发动机、变速器、传动机构、操纵机构、车身等总成和部件都安装于车架上。
二、车架的类型
汽车上装用的车架按其结构形式不同可分为：边梁式车架、中梁式车架、综合式车架和无梁式车架。边梁式车架由位于右左两侧的两根纵梁和若干横梁构成，横梁和纵梁一般由16Mn合金钢板冲压而成，两种者之间采用铆接或焊接连接。中梁式车架只有一根位于汽车中央的纵梁。纵梁断面为圆形或矩形其上固定有横向的托架或连接梁，使车架成鱼骨。
车桥
一、作用车桥通过悬架与车架连接，支承着汽车大部份重量，并将车轮的牵引力或制动力，以及侧向力经悬架传给车架。
二、类型汽车的车桥分为整体式和断开式两种。按使用功能划分，车桥又可分为转向桥、转向驱动桥、驱动桥和支持桥。
1、转向桥
安装转向轮的车桥叫转向桥。现代汽车一般都是前桥转向，也有少数是多桥转向的。
a、与非独立悬架匹配的转向车桥
这类转向桥结构大体相同，主要由前梁，转向节，主销和轮毂等部分组成。车桥两端与转向节绞接。前梁的中部为实心或空心梁。
b、与独立悬架匹配的转向桥
断开式转向桥的作用与非断开式转向桥一样，所不同的是断开式转向桥与独立悬架匹配，断开式车桥为活动关节式结构。
c、转向车轮定位
为了使汽车保持稳定的直线行驶，转向轻便、减少轮胎与转向机构的摩损，要求装配后的转向车轮、转向节和前轴与车架有正确的相对位置。前轮、前轴、转向节与车架的相对安装位置，称为转向车轮定位，也称前轮定位。前轮定位包括主销后倾、主销内倾、前轮外倾、前轮前束四个参数。
●主销后倾：主销装在前轴上后，其上端略向外倾，称为主销后倾。
●主销内倾：主销装在前轴上后，其上端略向内倾，称为主销内倾。
●前轮外倾：汽车的前轮安装后，其旋转平面上方略抽外倾，称为前轮外倾。
●前轮前束：汽车两个前轮的旋转平面不平行，前端略向内收，称为前轮前束。汽车的前束值一般小于10mm，通过改变横拉杆的长度可以调整前束的大小。
2、支承桥
转向桥和支持桥都属于从动桥。有些单桥驱动的三轴汽车，往往将后桥设计成支持桥。挂车上的车桥也是支持桥。发动机前置前驱动轿车的后桥也属于支桥。
Amee2020 Shanghai international automobile chassis system andManufacturing Engineering Technology Exhibition
[contact: Miss Ma with wechat]
Frame
1、 Functional frame is the base of automobile, such as engine,transmission, transmission mechanism, control mechanism, body andother assemblies and components are installed on the frame.
2、 Type of frame
According to the different structure forms, the frame ofautomobile can be divided into side beam frame, middle beam frame,comprehensive frame and non beam frame. The side beam frame iscomposed of two longitudinal beams and several transverse beams onthe right and left sides. The transverse beams and longitudinalbeams are generally made of 16Mn alloy steel plate by stamping, andthe two are connected by riveting or welding. The center beam framehas only one longitudinal beam in the center of the car. Thelongitudinal beam section is circular or rectangular, on which atransverse bracket or connecting beam is fixed to make the framefishbone.
Axle
1、 The action axle is connected with the frame through thesuspension, supporting most of the weight of the car, and transmitsthe traction or braking force of the wheel and the lateral force tothe frame through the suspension.
2、 There are two types of axles: integral type and disconnectedtype. According to the use function, the axle can be divided intosteering axle, steering drive axle, drive axle and supportaxle.
1. Steering axle
The axle on which the steering wheel is installed is called thesteering axle. Modern cars usually turn at the front axle, and afew turn at multiple axles.
a. Steering axle matched with dependent suspension
The structure of this kind of steering axle is basically thesame, mainly composed of front beam, steering knuckle, main pin andhub. The two ends of the axle are hinged with the knuckle. Themiddle part of the front beam is a solid or hollow beam.
b. Steering axle matching independent suspension
The function of the split steering axle is the same as that ofthe non split steering axle. The difference is that the splitsteering axle is matched with the independent suspension, and thesplit axle is a movable joint structure.
c. Steering wheel alignment
In order to keep the vehicle running in a stable straight line,turn easily and reduce the friction between the tire and thesteering mechanism, it is required that the assembled steeringwheel, knuckle and front axle have the correct relative positionwith the frame. The relative installation position of front wheel,front axle, knuckle and frame is called steering wheel alignment,also known as front wheel alignment. Front wheel alignment includesfour parameters: kingpin caster, kingpin inclination, front wheelcamber and front wheel toe in.
● kingpin caster: when the kingpin is installed on the frontaxle, its upper end slightly tilts outward, which is called kingpincaster.
● kingpin inclination: when the kingpin is installed on thefront axle, its upper end slightly inclines inward, which is calledkingpin inclination.
● front wheel camber: after the front wheel of the car isinstalled, the front wheel camber refers to the slight camber onthe rotating plane.
● front wheel toe in: the rotation plane of the two front wheelsof the car is not parallel, and the front end slightly retractsinward, which is called front wheel toe in. The toe in value of thecar is generally less than 10 mm. The toe in size can be adjustedby changing the length of the tie rod.
2. Supporting bridge
Both the steering axle and the support axle belong to the drivenaxle. Some single axle drive three axle vehicles often design therear axle as a support axle. The axle on the trailer is also thesupport axle. The rear axle of the front engine driven car alsobelongs to the branch axle.