汽车车架设计(中英翻译)

1、毕 业 设 计 英 文 翻 译汽车设计车架设计学 院： 汽车与交通学院 班 级： 学生姓名： 指导教师： 职 称： 2013 年 5月 30日Automobile Design-Frame DesignsThe vehicle frame is the basic platform to which all suspension and steering linkage parts attach. A vehicle will neither steer nor handle well if the frame is too flexible. A rigid frame structure

2、may pass unnecessary vibrations into the passenger compartment. The frame and suspension design will affect the ride quality, handling, and durability, as well as the levels of both noise and vibration.Manufacturers use several different types of construction on their vehicles. Of these, separate bo

3、dy and frame construction was the most common through the 1970's. It is still used in large vans, pickups, and trucks. In this type of construction, the engine, drive line, running gear, and body mount to the frame through insulators. Insulators are synthetic rubber pads that keep road and engin

4、e noise and vibration from going into the passenger compartment.A second type of construction is the unitized body. This, design is by far the most popular in modern vehicles. The unitized design has a lightweight structure with the required strength. Tn this type of construction, the frame is welde

5、d into the body as part of the body structure. Body panels add strength to the frame pieces. The running gear and drive line are mounted to the unitized body through large, soft synthetic rubber insulators. The insulators minimize the transfer of noise and vibration. If the insulators are too soft,

6、they will allow too much running gear and drive line movement. This movement, called compliance, affects vehicle handling and control. If the insulators are too hard, they will not insulate noise and vibration as they should. The manufacturer carefully designs the insulators and puts them where they

7、 will be in a vehicle with low noise and vibration transmission that still has proper handling and feel. Insulator properties change with age, changing original characteristics as the vehicle becomes older.A third type of construction combines the features of the first and second types. It uses a st

8、ub frame from the bulkhead forward and a unitized body from the bulkhead back. The unitized part is very rigid, while the stub frame provides a place for good insulation.Manufacturers select the type of construction .that is most economical to build,' while providing the noise, vibration, and ri

9、de and handling characteristics they want in the vehicle. Large older vehicles, vans, and trucks generally use separate body and frame construction. The newer, smaller' vehicles generally use unitized construction.The machine piston connecting rod setThe piston connecting rod set is composed of

10、the piston, piston wreath, piston pin, connecting rod, connecting rod axle bush, etc.effect: The effect of the piston is to bear the air pressure, and pass to connecting rod to drive the bent axle to revolve through connecting rod axle bush, the piston coping is still a part of the burning room. The

11、 work condition: Piston works under the condition of heat, high pressure, high speed, and bad lubrication .Piston directly contacts with the heat air. The temperature can amount to above 2500 Ks in a moment .The piston is heated severely, but the condition of spreading the hot is bad .So while the p

12、iston works, the temperature is very high and the coping is up to the 600-700 Ks: And the temperature distributes asymmetrically; The piston coping bears great air pressure, especially the pressure is greatest in the route of doing efficacy. The gasoline machine is up to the 3-5MPas, the diesel engi

13、ne is up to the 6-9MPas.This makes the piston produce pound, and     bear the function of the side pressure. Therefore, the piston should have enough heat-proof, try to decrease the heating area, strengthen the cooling of the piston, to make the highest temperature of the coping

14、descend .The piston moves at very high speed(8-12 ms/ s) back and forth in the air cylinder, and speed changes constantly, This produces very great inertial dint, making the piston bear great additional load working under such bad condition, the piston will become deformed heating power. At the same

15、 time ,it slitters the chemical corrosive power of the burning gas .In order to descend the inertial dint of back and forth, we must ease the weight of the piston as possible .Piston works under the condition of the heat, high pressure, high speed(the average speed can amount to the 101115 m/ s), an

16、d its lubricant condition is bad and the frication between the piston and the air cylinder wall is very great. In order to descend the friction, the surface of the piston surface must be wear-resistant.Request:1) To have enough rigidity and strength, and the reliable dint;2) Transmit heat well, bear

17、 the high pressure, bear the heat and bear to wear away;3) the quantity is small, the weight is light, descend the inertial dint of back and forth as possibleThe aluminum metal alloy material satisfies the top requests basically, therefore, the piston generally adopts the high strength aluminum meta

18、l alloy, but some low speed diesel engines adopt high class iron casting or heat-proof steelstructure: The piston can be divided into three parts, piston coping, the piston head and piston skirt departments.1. The piston copingThe piston coping bears the air pressure, it is a part of the burnable ro

19、om .Its shape, position, size are relevant to the concrete from of the burnable room. They are made to satisfy the combustible hybrid spirit formation and burnable requests. Its coping shape can be divided into four major types, a flat coping piston, a convex coping piston, a concave coping piston a

20、nd model piston.A convex coping piston is usually used on the two blunt distance I.C. engines, It is good to improve the process exchanging the gas .Modern four blunt the distance gasoline machine also adopts the convex coping piston in order to strengthen the effect of pushing the gas or extend the

21、 ratio of compressing .Convex of a piston coping presents a form of ball, its coping strength is high, having an effect of leading, being advantageous to improve the process of exchanging the gas, two route of travel gasoline machines often adopt the convex coping pistonA piston coping presents the

22、hollow form, the shape and positions of the cave pit must be advantageous to the combustion of the combustible and hybrid gas, having a pair of eddies concave pit ball, concave pit, U concave pit, and so on.Piston head The piston refers to the first piston wreath to the part above the piston pi

23、n.It has several wreath slots, which are used to install the piston wreath and have an effect of sealing completely. It is also called the leak proof department .The diesel engines compress ratio is high, and generally have four wreath slots, The three upper wreaths are used to install, the lower pa

24、rt installs the oil wreath. The gasoline machine has three wreath slots generally, which are two jet of gas wreath slots and an oil wreath slots. At the bottom of oil wreath slot many paths toward eyelet are drilled to make the quilt oil wreath flow from the air cylinder wall  to the oil bottom

25、 hull through these eyelets. The working condition of the wreath slot is the worst and should leave the coping generally a little farther.Above the gas wreath, a narrow insulating slot is usually set to cut off the heat flow which is spread from the piston coping to the first gas wreath and make par

26、ts of calories from a piston wreath spread, thus easing the hot burden of the first gas wreath. On some engines small wreathe slots are often made between the coping head and the first gas wreathe, sometimes till a few more wreath. This kind of small wreath can adsorb the lubricant because it accumu

27、lates the carbon. It can keep piston and the air cylinder walls from biting to match when it work in the condition of losing oil, so it is called accumulating the carbon slot.The calories that the piston coping absorbs also mainly passes the air cylinder wall through the piston wreath to leak proof

28、department, again spread by the cool water.In a word, the function of the piston head is in addition to install the piston wreath, still seal completely function and transmit heat function, sealing completely the air cylinder together with the piston wreath, keeping combustible admixture spirit from

29、 leak crankcase, at the same time pass the(70-80)%calories to the air cylinder wall through the piston wreath.3. Piston skirt departmentThe piston skirt department refers to the parts from the bottom of the oil wreathe slot. It includes the pin which is used to pack the piston. The piston skirt depa

30、rtment exercises to rise to lead to the function to the piston in the back and forth in the air cylinder, and bear the side pressure. The length of the skirt department is decided by the size and the piston diameter of the side pressure. The so-called side pressure mean in the compression route of t

31、ravel and make route of travel of efficacy .The level component of the gas pressure which take effect on the piston coping presses the piston to the air cylinder wall. Compress the route of travel and make the side pressure direction of the efficacy route of travel air exactly the opposite, because

32、of the combustion pressure consumedly high in compress the pressure, so, make the side in the route of travel of efficacy pressure also consumedly high in compress the side in the route of travel pressure.Two on the sides that bear the side pressure of the piston skirt department be called to push t

33、he dint to face, they be placed in to sell the mutually perpendicular direction of the stalk line with piston up.Drive LinesThe drive line includes all the parts from the and final drive carry the torque from the engine, the other.  The engine torque during acceleration and the torque during br

34、aking place loads on the suspension parts.During suspension repair, it may be essary to disassemble parts of the drive line. Noises produced when the suspension moves may originate from drive line parts. A basic understanding of different drive line assemblies is presented here to give you a working

35、 knowledge so that you can do suspension repair.Drive lines with front-wheel drive often combine the transmission and the final drive into one assembly. This is also true of mid-and rear-engine vehicles. The assembly is called a transaxle, Short half-shafts with universal joints at each end connect

36、between the transaxle and the wheels. These shafts carry power from the final drive to the wheels even when the suspension moves and steers.A differential in the final drive splits incoming power, sending half to each drive wheel. This allows the drive wheels to turn at different speeds while roundi

37、ng corners. The transmission Other parts form the link from one part to while cornering.In front-engine, rear-wheel drive vehicles, the transmission is located under the front floor of the passenger compartment. A drive shaft is used to carry engine power to the rear axle. The drive shaft has a univ

38、ersal joint at each end. It carries power through the changing drive line angles as the suspension moves.A vehicle with independent suspension at the drive wheels has the final drive attached rigidly to the vehicle frame or the engine. This drive arrangement produces forces, without any torques, on

39、the suspension parts during acceleration. If the brakes are mounted inboard so the caliper mounts to a frame piece and not to a suspension, the brake will also not produce a torque on the suspension. A suspension designed to handle only acceleration and braking torques can be designed differently th

40、an one that must handle both suspension forces and torques.Suspension SystemsThe suspension includes springs, shock absorbers, and control linkages. It must be strong enough to support the vehicle body and load. The suspension must also resist engine and brake reactions. The most important job of th

41、e suspension is to keep the tires in contact with the road as much of the time as possible. This is done while supporting the vehicle and its load, even while traveling over rough roads. The four tire footprints are the only place the vehicle touches the road. All of the engine power, steering, and

42、braking forces operate through the tire-to-road footprints. Control of the vehicle ( power, steering and braking) is reduced or lost any time a tire does not stay on the road or when skidding begins.The vehicle body is supported by springs. The springs can be of the coil, leaf, torsion bar, or pneum

43、atic type. Coil springs are the most popular design used in the modern automobile. Coil, torsion bar, and pneumatic springs all require links and arms to hold the wheel in position. Leaf springs provide lateral and longitudinal control to prevent unwanted wheel motions.  They are commonly found

44、 on vans and trucks.Suspension systems have been changed and refined as the passenger automobile has developed. Design objectives differ between luxury sedans, performance vehicles, small compact vehicles, and light trucks. Tire improvements, along with improvements in shock absorbers, steering syst

45、ems, and suspension control devices, have continually upgraded vehicle handling characteristics.Tire-to-road contact is needed for safe, positive vehicle control under all operating conditions. Keep in mind that all four tires must stay in contact with the road at all times for maximum vehicle contr

46、ol. Compromises are made in handling response, tire wear, driver comfort, and ride harshness to achieve positive vehicle control.Suspension systems are divided into front suspension and rear suspension.Front suspension designs have developed from relatively rugged solid-axle designs to the modern li

47、ghtweight, high-strength , strut-type independent designs. These have been upgraded with added linkage. Suspension design improvements have followed improvements in roadways and driver expectations.Most front-engine, rear-wheel-drive vehicles use a simple dependent rear suspension .Rear-wheel-drive

48、independent suspension is much more complex and expensive. As a result, it is only used on a few passenger vehicles.To front-engine, front-wheel-drive vehicles by moving the drive train to the front, only ride control and braking reactions are controlled by the rear suspension. This has led to the u

49、se of simplified dependent suspension , semi-independent suspension and independent rear suspension. The latter is used in a larger number of new vehicle designs.Steering SystemsThe driver controls the direction of the front wheels of the vehicle through the steering gear. Modern steering gears have

50、 two major units* a steering column and a gear unit. Tin-steering column has a supported shaft that connects the driver's steering wheel to the gem unit.  The gear unit multiplies the driver's steering effort to move the steering linkage.The front wheels of rear-wheel-drive vehicles rot

51、ate on a spindle. The spindle is part ol the steering knuckle . The knuckle is connected to the front suspension members with ball joints. The ball joints allow for steering as the suspension moves up and down. The wheel hubs on front-wheel-drive vehicles rotate on hollow axle stub shafts inside bea

52、rings within the steering knuckles.The steering wheel controls the steering gear assembly. This, in turn, moves the knuckle through the steering linkage. Two steering gear designs are in use today, the rack and pinion and recirculating ball.vehicles are designed with responsive steering. As a result

53、, more effort is needed to steer the vehicle when it is moving slowly. Power steering supplies this effort on many vehicles.With power steering doing most of the work, steering ratios are decreased so that the vehicle can be steered with small steering wheel movements. The power steering gear is sim

54、ilar to the standard steering gear. It includes surfaces upon which fluid pressure is applied to aid the driver's steering effort. Both rack and pinion and recirculating ball gears may have power assist.Power for the steering gear is provided by an engine-driven pump. The pump forces power steer

55、ing fluid through a system controlled by a valve. This control valve can sense the driver's steering effort. It puts fluid pressure against a pressure surface in the steering system.  This fluid pressure takes over some of the effort needed to steer the vehicle.The steering column in the mo

56、dern vehicle has many parts. It is designed to collapse or fold in a vehicle collision to protect the driver. In some installations, it may be tilted and telescoped to adjust the position of the steering wheel for the comfort of the driver. To reduce the chance of theft, it also has a steering gear

57、lock. On many vehicles, it has a transmission lock. Because it is within easy reach of the driver, the steering column may carry the transmission shift control lever, turn signal switch, headlight and dimmer switches, wiper switch, emergency flasher switch, and speed control.Brake SystemsService bra

58、kes must be able to stop the vehicle, prevent excess speed when coasting, and hold the vehicle in position while it is stopped on grades. They are designed so the driver can adjust the braking effort to maintain vehicle control. Vehicle control is influenced by brakes as well as the suspension and s

59、teering systems. Faults in the brake system can lead to wheel pull during braking. To repair suspension systems, parts of the brake system may require disassembly.  For these reasons, the brake system will be discussed briefly in this text.The brake system must provide smooth stopping power that can be controlled by the driver. The force required on the brake pedal must not be so high that the wheels cannot be locked.