1、Unit SixSuspension System and Steering System Passage BSteering System The function of a steering system is to control the direction of a moving car and to convert the rotary movement of a steering wheel in drivers hands into the turning movement of a front wheels on road A good steering system make
2、s driving much more pleasurable,comfortable and safer Typically,a steering system consists of a steering wheel,steering gear,steering shaft and steering linkage(see Fig.6-8).Nowadays,two types of steering gear are mainly used:rack-and-pinion steering gear and recirculating-ball steering gear Rack-an
3、d-pinion steeringgear Many modern cars use rack-and-pinion steering gear It provides better direct steering feel for driver and more accurate wheel control to make steering more responsive Rack-and-pinion steering gear contains following main components:rack and pinion The rack is a long bar with te
4、eth on it The pinion at the end of the steering shaft is in mesh with the rack(see Fig.6-9).The steering linkage contains tie rods and steering arms The inner tie rod ends are attached to each end of the rack The outer tie rod ends are attached to the steering arms(see Fig.6-10).Recirculating-ball s
5、teering gear Recirculating-ball steering gear is commonly found on many trucks and off-road vehicles today This type of steering gear is low in friction for a heavy automobile because the larger and heavier the automobile is,the more difficult it is to steer Recirculating-ball steering gear contains
6、 following main components:worm gear,ball nut,steel balls and sector gear,which are all in one steering gear box In the box,the ball nut rides on the worm gear atthe end of the steering shaft The ball nut has internal threads filled with steel balls that are meshed with the worm gear The ball nut ha
7、s external teeth which are meshed with the sector gear that is attached to the pitman arm shaft(seeFig.6-11).The steering linkage contains a pitman arm,an idler arm,a center link,tie rods and steering arms The pitman arm is attached to the sector gear,and idler arm is attached to the frame The cente
8、r link connects the pitman arm to the idler arm The tie rods connect the center link to the steering arms(see Fig.6-12).Power steering system Today,almost of all cars are equipped with a power steering system This system help driver steer more easily when a car is turning a corner Power steering sys
9、tem sare divided into hydraulic power-assisted steering system,electro-hydraulic power-assisted steering system,electric power-assisted steering system and steer-by-wire system Hydraulic power-assisted steering system(HPS)HPS contains following main components:power steering pump,control valve,power
10、 cylinder,oil lines and power steering oil reservoir The pump is driven by the engine through the belt,producing hydraulic pressure The control valve is designed to sense the force on the steering wheel and direct the fluid in the oil lines to the cylinder which converts the pressure into steering f
11、orce to make steering more easily The oil reservoir acts as storage for steering oil(see Fig.6-13).HPS is now rarely used on modern cars Electro-hydraulicpower-assisted steering system(EHPS)EHPS is the same in operating principle as HPS The difference is that the pump is driven by the electric motor
12、,instead of the engine That is,the motor power converts to hydraulic pressure to assist steering In addition,it is also equipped with ECU,torque sensor,and solenoid valve ECU,motor,pump and oil reservoir are all in a power pack(see Fig.6-14).Electric power-assisted steering system(EPS)EPS mainly con
13、tains torque sensors,speed sensors,ECU and electric motor(see Fig.6-15).When driver turns the steering wheel,the torque sensors sense the steering direction and the amount of torque,then send the information to ECU According to the information from torque sensors and speed sensors,ECU commands the e
14、lectric motor to provide the power-assisted steering Steer-by-wire System(SBW)SBW is a new and innovative steering system It is quite different from the other steering systems As Fig.6-16 is shown,we can see that SBW eliminates the mechanical connection between the steering wheel and the wheels of a
15、 car,that is,no steering shaft in between In addition to ECU,its main components are steering actuator,feedback motor,steering angle sensors It uses the motors to change the direction of the wheels and to provide feedback to the driverNew Words and Expressions steering stiri n 转向 accurate kjrt adj 精
16、确的 responsive rispnsiv adj 响应的,敏感的 external ikstnl adj 外部的;表面的 feedback fidbk n 反馈Common Automobile Terms steering system转向系统 steering gear转向器 steering shaft转向轴 steering linkage转向杆系 rack-and-pinion steeringgear齿轮齿条式转向器 recirculating-ball steeringgear循环球式转向器 tie rod转向横拉杆 steering arm转向臂 worm gear蜗杆 b
17、all nut循环球螺母 sector gear齿扇 pitman arm转向摇臂Common Automobile Termsidler arm随动臂center link中间拉杆power steering system助力转向系统hydraulic power-assisted steering system液压助力转向系统electro-hydraulic power-assisted steering system电子液压助力转向系统electric power-assisted steering system电动助力转向系统steer-by-wire system线控转向系统power steering pump动力转向油泵control valve转向控制阀power cylinder转向助力缸oil line油路,液压油管路power steeringoil reservoir 动力转向油罐Common Automobile Terms oil line油路,液压油管路 power steeringoil reservoir 动力转向油罐 solenoid valve电磁阀 power pack动力机组 steering actuator转向执行器 feedback motor反馈电机 steering angle sensor转向角传感器
