转向系设计英文文献及翻译.docx

1、转向系设计英文文献及翻译Fundamentals of AutomobileToday is average car contains more than 15,000 separate, individual parts that must work together. These parts can be grouped into four major categories: engine, body, chassis and electrical and electronic equipment(Fig.1.1).1 EngineTheengine acts as the power u

2、nit. The internal combustion engine is most common: this obtain its power by burning a liquid fuel inside the engine cylinder. There are two types of engines: gasoline engine (also called a spark ignition engine) and diesel (also called a compression-ignition engine). Both engines are called heat en

3、gines; the burning fuel generates heat which causes the gas inside the cylinder to increase its pressure and supply power to rotate a shaft connected to the transmission.2 BodyAn automobile body is a sheet metal shell with windows, doors, a hood, and a trunk deck built into it. It provides a protect

4、ive covering for the engine, passengers, and cargo. The body is designed to keep passengers safe and comfortable. The body styling provides an attractive, colorful, modern appearance for the vehicle.3 chassisThe chassis is an assembly of those systems that are the major operating parts of a vehicle.

5、 The Chassis includes the transmission, suspension, steering, and brake system.3.1 TransmissionThe transmission system comprises clutch, gearbox, propeller shaft, rear axle and differential and the driven road wheels.ClutchThe clutch or torque converter has the task of disconnecting and connecting t

6、he engines power from and to the driving wheels of the vehicle. This action may be manual or automatic.GearboxThe main purpose of the gearbox is to provide a selection of gear ratios between the engine and driving wheels, so that the vehicle can operate satisfactorily under all driving conditions. G

7、ear selection may be done manually by the driver or automatically by a hydraulic control system.Propellor shaftThe function of the propeller (drive) shaft is to transmit the drive from the gearbox to the input shaft of the rear axle and differential assembly. Flexible joints allow the rear axle and

8、wheels to move up and down without affecting operation.The role of the drive shaft from the transmission the driving force transmitted to the rear axle input shaft and the differential assembly. Universal joint allows the rear axle and wheels move up and down without affecting operation.Rear axle an

9、d differentialTherear axle and differential unit transmits the engines rotational power through 90 from propshaft to axle shaft to axle shaft to road wheels. A further function is to allow each driven wheel to turn at a different speed; essential when cornering because the outer wheel must turn furt

10、her than the inside wheel. A third function is to introduce another gear ratio for torque multiplication.3.2 SuspensionThe axles and wheels are isolated from the chassis by a suspension system . The basic job of the suspension system is to absorb the shocks caused by irregular road surfaces that wou

11、ld otherwise be transmitted to the vehicle and its occupants, thus helping to keep the vehicle on a controlled and level course, regardless of road conditions.3.3 SteeringThe steering system, under the control of the driver at the steering wheel, provides the means by which the front wheels are dire

12、ctionally turned. The steering system may be power assisted to reduce the effort required to turn the steering wheel and make the vehicle easier to manoeuvre.3.4 BrakesThe braking system on a vehicle has three main functions. It must be able to reduce the speed of the vehicle, when necessary; it mus

13、t be able to stop the car in as short a distance as possible; it must be able to hold the vehicle stationary. The braking action is achieved as a result of the friction developed by forcing a stationary surface(the brake lining)into contact with a rotating surface(the drum or disc). Each wheel has a

14、 brake assembly of either the drum type or the disc type, hydraulically operated when the driver applies the foot brake pedal.4 Electrical Equipment and InstrumentationTheelectrical system supplies electricity for the ignition, horn, lights, heater, and starter. The electricity level is maintained b

15、y a charging circuit. This circuit consists of a battery, and an alternator (or generator). The battery stores electricity. The alternator changes the engines mechanical energy into electrical energy and recharges the battery.The motor vehicle incorporates a number of electrical devices that are use

16、d for:Battery charging alternator and regulator.Engine purposes starting and ignition. Safety and convenience lighting, horn, wipers, washers etc.Driver information instrumentation and warning lamps.Of these devices instrumentation is, perhaps, most influenced by the advance of microelectronics. The

17、 basic electromechanical systems of:Speedometer for indicating vehicle speed.Engine oil pressure warning lamp or gauge to show operating limits.Engine coolant temperature warning lamp or gauge to show operating limits.Battery charging warning lamp or gauge to indicate satisfactory/unsatisfactory act

18、ion.Fuel tank content gauge to show amount of fuel in the fuel tank.are giving way to computerized vehicle management information centres.The Steering System1 The Steering GearThe steering gear mechanism enables the driver to turn the front wheels of the car. The mechanism consists of a steering gea

19、r box, pitman arm, drag link, tie rods, steering arms, and steering knuckles, the latter supporting the front wheels(Fig.6.1).Turning the steering wheel turns the steering shaft to which a worm gear is attached within the steering gear box. The steering worm moves a roller through a part of an arc,

20、the motion of which is transmitted to the pitman arm, which moves back and forth across the width of the frame. Several arrangements of rods and levers are in common use but, in general, a drag link, connected to the pitmen arm, transmits the movement to tie rods which are connected to the steering

21、arms. Sideward movement of the steering arms turns the steering knuckles, and the wheels, as they are pivoted on front end support mechanism.There are two types of steering system: manual steering system and power steering system. In the manual type, the driver does all the work of turning the steer

22、ing wheel, steering gears, wheels, and tires. In the power type, hydraulic fluid assists the operation so that the drivers effort is reduced.Mechanical steering system: And changes the transmission system by the diverter to be composed. Diverter: By the steering wheel, the steering wheel steering ax

23、le, changes meshing to pay (diverter) to be composed. Steering transmission system: By drop arm (drop arm), drag link, drag link arm, about trapezoidal arm, steering knuckle tie rod, if a dry bulb joint composes.Power steering system: Changes the augmenter constitution by mechanical steering system

24、Canada.A typical power steering system needs a power steering pump and reservoir in addition to the steering gear(Fig.6.2). These parts store the hydraulic fluid and provide the hydraulic pressure to assist steering. In most instances, a V-belt from the engine power the hydraulic pump. Hoses lead fr

25、om the pump to the steering gear and back to the pump.In steering gear box the gear is slightly larger and has other parts. The wormshaft is the same in both systems. Instead of a ball nut, though, the power steering system uses a power piston or rack piston in steering gear box. The power piston ha

26、s teeth on one side that mesh with the sector teeth. The forward and backward motion of the power piston moves the sector, pitman shaft, and steering linkage.The power steering gear also uses a control valve to send hydraulic fluid into the steering gear at the right time. When the steering wheel st

27、arts to move in either direction, the valve opens its ports to sent fluid under pressure into the main chamber of the steering gear. The fluid pushes against the power piston and assists the motion of the steering wheel.Fig.6.2 In an integral power steering system, the power andcontrol are in the sa

28、me housing as the steering gear 2 Front-GeometryThe front wheels are arranged at various angles to the car frame to provide good steering control and stability. The angles are discussed in the following order: caster, camber, steering axis inclination, toe, and turning radius.Caster is the slant of

29、the kingpin forward at the bottom(Fig.6.3). (NOTE: Modern passenger car does not use a kingpin in an independently mounted front wheel suspension, but reference to its former position helps to clarify some front end concepts. The position of the kingpin would be on a direct line drawn between the tw

30、o ball joints). The front wheels, when provided with the proper amount of caster, will align themselves in the direction in which the car is moving. Too much caster will cause hard steering and shimmy at low speed. Too little caster will cause wander or weave at high speed and erratic steering when

31、applying the brakes.Camber is the angle between a vertical line and a line drawn through the center of the wheel(Fig.6.4). The top of the wheel is inclined away from the car. The purpose of camber is to place the center of the tire directly under the extended line of the kingpin for easier steering.

32、 This places the weight of the car directly over the pivot point.Steering Axis Inclination is the outward tilt of the bottom of the kingpin toward the wheel(Fig.6.5). Modern engineering practice is to minimize camber in order to reduce uneven tire wear, and increase theFig.6.3 Caster Fig.6.4 Camberangular inclination of the kingpin to place its centerline directly under the center of the tire for ease in steering.Steering axis inclination also provides steering stability by raising the entire front end of the vehi