外文翻译---汽车悬架系统概述
汽车英语悬架系统(suspension system)
The characteristics of nonindependent suspension
• Simple structure（结构简单） • Low cost（成本低） • Simple fabrication process（制作工艺简单）
The type of suspension
• Independent suspension（独立悬架） • non-independent suspension（非独立悬架）
The characteristics of independent on
• Comfortable（舒适性好） • Reasonable structure（结构紧凑） • Beneficial for shift/turning （有利于转向） • Light weight, wheels’ firm contact with
Graphic Suspension
(横向推力杆) Coil spring （线圈弹簧） Sock absorber（减震器H）orizontal thrust rod
(横向稳定器) Horizontal stabilizer
Cross member（横梁） Vertical thrust rod (纵向推力杆)
Suspension system components
• Shock absorber • Coil spring • Lower control arm • Cross member • Trailing arm • Stub axle • Steering knuckle
（减震器） （线圈弹簧） （下控制臂）
Unit 5
Suspension System
Automobile Suspension System汽车悬架系统
Automobile Suspension System汽车悬架系统Automobile suspension systemhas two basic functions, to keep car's wheels in firm contact with the road and to provide comfortable ride form the passengers. A lot of the system's work is done by the spring. Under normal conditions, the springs support the body of the car evenly by compressing and rebounding with every up-and-down movement. This up-and-down movement, however, causes bouncing and swaying after each bump and is very uncomfortable to the passenger.This uncomfortable effects are reduced by the shock absorbers.汽车悬架系统有两个作用:保持汽车车轮与路面的良好接触，提供乘客的乘坐舒适性。
大量的工作是由弹簧来完成的。
在正常情况下，弹簧通过压缩和伸张均匀地支撑着车身上下运动。
车身的上下运动在每一次冲击后会引起跳动和摆动，这样会使得乘客很不舒服。
这种不舒适性可以通过减震器来降低。
Suspension, when discussing cars, refers to the use of the front and rear springs to suspend a vehicle's "sprung" weight. The springs used on today's cars and trucks are constructed in avariety of types, shapes, sizes, rates and capacities. Types include leaf springs, coil springs, air springs, and torsion bars. They may be paired off on vehicles in various combinations and are attached to vehicles by several different mounting techniques.当我们谈论汽车悬架时，是指前后弹簧用来悬挂的汽车重量。
汽车悬架原理外文文献翻译中英文
汽车悬架原理外文文献翻译(含：英文原文及中文译文)文献出处：Journal of Biomechanics, 2013, 4(5):30-39.英文原文The rinciple of Car SuspensionsWilliam HarrisUniversity of MichiganWhen people think of automobile performance, they normally think of horsepower, torque and zero-to-60 acceleration. But all of the power generated by a piston engine is useless if the driver can't control the car. That's why automobile engineers turned their attention to the suspension system almost as soon as they had mastered the four-stroke internal combustion engine.The job of a car suspension is to maximize the friction between the tires and the road surface, to provide steering stability with good handling and to ensure the comfort of the passengers. In this article, we'll explore how car suspensions work, how they've evolved over the years and where the design of suspensions is headed in the future.1.V ehicle DynamicsIf a road were perfectly flat, with no irregularities, suspensions wouldn't be necessary. But roads are far from flat. Even freshly paved highways have subtle imperfections that can interact with the wheels of acar. It's these imperfections that apply forces to the wheels. According to Newton's laws of motion, all forces have both magnitude and direction. A bump in the road causes the wheel to move up and down perpendicular to the road surface. The magnitude, of course, depends on whether the wheel is striking a giant bump or a tiny speck. Either way, the car wheel experiences a vertical acceleration as it passes over an imperfection. Without an intervening structure, all of wheel's vertical energy is transferred to the frame, which moves in the same direction. In such a situation, the wheels can lose contact with the road completely. Then, under the downward force of gravity, the wheels can slam back into the road surface. What you need is a system that will absorb the energy of the vertically accelerated wheel, allowing the frame and body to ride undisturbed while the wheels follow bumps in the road.The study of the forces at work on a moving car is called vehicle dynamics, and you need to understand some of these concepts in order to appreciate why a suspension is necessary in the first place. Most automobile engineers consider the dynamics of a moving car from two perspectives:1)Ride - a car's ability to smooth out a bumpy road2)Handling - a car's ability to safely accelerate, brake and cornerThese two characteristics can be further described in three important principles - road isolation, road holding and cornering. The table belowdescribes these principles and how engineers attempt to solve the challenges unique to each.A car's suspension, with its various components, provides all of the solutions described.2.The Chassis SystemThe suspension of a car is actually part of the chassis, which comprises all of the important systems located beneath the car's body.These systems include:1) T he frame - structural, load-carrying component that supports the car's engine and body, which are in turn supported by the suspension2) T he suspension system - setup that supports weight, absorbs and dampens shock and helps maintain tire contact3) T he steering system - mechanism that enables the driver to guide and direct the vehicle4) T he tires and wheels - components that make vehicle motion possible by way of grip and/or friction with the roadSo the suspension is just one of the major systems in any vehicle.With this big-picture overview in mind, it's time to look at the three fundamental components of any suspension: springs, dampers and anti-sway bars.3.SpringsToday's springing systems are based on one of four basic designs:1) Coil springs - This is the most common type of spring and is, in essence, a heavy-duty torsion bar coiled around an axis. Coil springs compress and expand to absorb the motion of the wheels.2) Leaf springs - This type of spring consists of several layers of metal (called "leaves") bound together to act as a single unit. Leaf springs were first used on horse-drawn carriages and were found on most American automobiles until 1985. They are still used today on most trucks and heavy-duty vehicles.3) Torsion bars - Torsion bars use the twisting properties of a steel bar to provide coil-spring-like performance. This is how they work: One end of a bar is anchored to the vehicle frame. The other end is attached to a wishbone, which acts like a lever that moves perpendicular to the torsion bar. When the wheel hits a bump, vertical motion is transferred to the wishbone and then, through the levering action, to the torsion bar. Thetorsion bar then twists along its axis to provide the spring force. European carmakers used this system extensively, as did Packard and Chrysler in the United States, through the 1950s and 1960s. 4) Air springs - Air springs, which consist of a cylindrical chamber of air positioned between the wheel and the car's body, use the compressive qualities of air to absorb wheel vibrations. The concept is actually more than a century old and could be found on horse-drawn buggies. Air springs from this era were made from air-filled, leather diaphragms, much like a bellows; they were replaced with molded-rubber air springs in the 1930s.Based on where springs are located on a car -- i.e., between the wheels and the frame -- engineers often find it convenient to talk about the sprung mass and the unsprung mass.4.Sprung and Unsprung MassThe sprung mass is the mass of the vehicle supported on the springs, while the unsprung mass is loosely defined as the mass between the road and the suspension springs. The stiffness of the springs affects how the sprung mass responds while the car is being driven. Loosely sprung cars, such as luxury cars (think Lincoln Town Car), can swallow bumps and provide a super-smooth ride; however, such a car is prone to dive and squat during braking and acceleration and tends to experience body sway or roll during cornering. Tightly sprung cars, such as sports cars (think Mazda Miata), are less forgiving on bumpy roads, but they minimizebody motion well, which means they can be driven aggressively, even around corners.So, while springs by themselves seem like simple devices, designing and implementing them on a car to balance passenger comfort with handling is a complex task. And to make matters more complex, springs alone can't provide a perfectly smooth ride. Why? Because springs are great at absorbing energy, but not so good at dissipating it. Other structures, known as dampers, are required to do this.5.Shock AbsorbersUnless a dampening structure is present, a car spring will extend and release the energy it absorbs from a bump at an uncontrolled rate. The spring will continue to bounce at its natural frequency until all of theenergy originally put into it is used up. A suspensionbuilt on springs alone would make for an extremely bouncy ride and, depending on the terrain, an uncontrollable car.Enter the shock absorber, or snubber, a device that controls unwanted spring motion through a process known as dampening. Shock absorbers slow down and reduce the magnitude of vibratory motions by turning the kinetic energy of suspension movement into heat energy that can be dissipated through hydraulic fluid. To understand how this works, it's best to look inside a shock absorber to see its structure and function.A shock absorber is basically an oil pump placed between the frame of the car and the wheels. The upper mount of the shock connects to the frame (i.e., the sprung weight), while the lower mount connects to the axle, near the wheel (i.e., the unsprung weight). In a twin-tube design, one of the most common types of shock absorbers, the upper mount is connected to a piston rod, which in turn is connected to a piston, which in turn sits in a tube filled with hydraulic fluid. The inner tube is known as the pressure tube, and the outer tube is known as the reserve tube. The reserve tube stores excess hydraulic fluid.When the car wheel encounters a bump in the road and causes the spring to coil and uncoil, the energy of the spring is transferred to the shock absorber through the upper mount, down through the piston rod and into the piston. Orifices perforate the piston and allow fluid to leakthrough as the piston moves up and down in the pressure tube. Because the orifices are relatively tiny, only a small amount of fluid, under great pressure, passes through. This slows down the piston, which in turn slows down the spring.Shock absorbers work in two cycles -- the compression cycle and the extension cycle. The compression cycle occurs as the piston moves downward, compressing the hydraulic fluid in the chamber below the piston. The extension cycle occurs as the piston moves toward the top of the pressure tube, compressing the fluid in the chamber above the piston.A typical car or light truck will have more resistance during its extension cycle than its compression cycle. With that in mind, the compression cycle controls the motion of the vehicle's unsprung weight, while extension controls the heavier, sprung weight.All modern shock absorbers are velocity-sensitive -- the faster the suspension moves, the more resistance the shock absorber provides. This enables shocks to adjust to road conditions and to control all of the unwanted motions that can occur in a moving vehicle, including bounce, sway, brake dive and acceleration squat.6.Struts and Anti-sway BarsAnother common dampening structure is the strut -- basically a shock absorber mounted inside a coil spring. Struts perform two jobs: They provide a dampening function like shock absorbers, and they provide structural support for the vehicle suspension. That means struts deliver a bit more than shock absorbers, which don't support vehicle weight -- they only control the speed at which weight is transferred in a car, not the weight itself.Because shocks and struts have so much to do with the handling of a car, they can be considered critical safety features. Worn shocks and struts can allow excessive vehicle-weight transfer from side to side and front to back. This reduces the tire's ability to grip the road, as well as handling and braking performance.7.Anti-sway BarsAnti-sway bars (also known as anti-roll bars) are used along with shock absorbers or struts to give a moving automobile additional stability. An anti-sway bar is a metal rod that spans the entire axle and effectively joins each side of the suspension together.When the suspension at one wheel moves up and down, the anti-sway bar transfers movement to the other wheel. This creates a more level ride and reduces vehicle sway. In particular, it combats the roll of a car on its suspension as it corners. For this reason, almost all cars today are fitted with anti-sway bars as standard equipment, although if they're not, kits make it easy to install the bars at any time.8.The Future of Car SuspensionsWhile there have been enhancements and improvements to both springs and shock absorbers, the basic design of car suspensions has not undergone a significant evolution over the years. But all of that's about to change with the introduction of a brand-new suspension design conceived by Bose -- the same Bose known for its innovations in acoustic technologies. Some experts are going so far as to say that the Bose suspension is the biggest advance in automobile suspensions since the introduction of an all-independent design.How does it work? The Bose system uses a linear electromagnetic motor (LEM) at each wheel in lieu of a conventional shock-and-spring setup. Amplifiers provide electricity to the motors in such a way that theirpower is regenerated with each compression of the system. The main benefit of the motors is that they are not limited by the inertia inherent in conventional fluid-based dampers. As a result, an LEM can extend and compress at a much greater speed, virtually eliminating all vibrations in the passenger cabin. The wheel's motion can be so finely controlled that the body of the car remains level regardless of what's happening at the wheel. The LEM can also counteract the body motion of the car while accelerating, braking and cornering, giving the driver a greater sense of control.Unfortunately, this paradigm-shifting suspension won't be available until 2009, when it will be offered on one or more high-end luxury cars. Until then, drivers will have to rely on the tried-and-true suspension methods that have smoothed out bumpy rides for centuries.中文译文汽车悬架原理研究作者：威廉·哈里斯密歇根大学当人们想到汽车性能时，他们通常会联想到马力，扭矩和零到60码加速度。
外文翻译---悬架系统的基本元件
附录Ⅰ外文资料及翻译As we review suspension system components and how they work together, remember that a vehicle in motion is more than wheels turning. As the tire revolves, the suspension system is in a dynamic state of balance, continuously compensating and adjusting for changing driving conditions. Today's suspension system is automotive engineering at its best.The components of the suspension system perform six basic functions:1.Maintain correct vehicle ride height2.Reduce the effect of shock forces3.Maintain correct wheel alignment4.Support vehicle weight5.Keep the tires in contact with the road6.Control the vehicle’s direction of travelHowever, in order for this to happen, all the suspension components, both front and rear, must be in good working condition.MAIN COMPONENTS OF A MODERN SUSPENSION SYSTEMAt this point, it's important to understand that the main components of a moving vehicle suspension system are the Struts, Shock Absorbers, Springs and Tires. We will first turn our attention to the design and function of springs. In the following section we will thoroughly examine the function and design of shock absorbers and strut assemblies.The springs support the weight of the vehicle, maintain ride height, and absorb road shock..Springs are the flexible links that allow the frame and the body to ride relatively undisturbed while the tires and suspension follow the bumps in the road.Springs are the compressible link between the frame and the body. When an additional load is placed on the springs or the vehicle meets a bump in the road, the springs will absorb the load by compressing. The springs are a very important component of the suspension system that provides ride comfort. Shocks and strutshelp control how fast the springs and suspension are allowed to move, which is important in keeping tires in firm contact with the road.During the study of springs, the term bounce refers to the vertical (up and down) movement of the suspension system. The upward suspension travel that compresses the spring and shock absorber is called the jounce, or compression. The downward travel of the tire and wheel that extends the spring and shock absorber is called rebound, or extension.When the spring is deflected, it stores energy. Without shocks and struts the spring will extend and release this energy at an uncontrolled rate. The spring's inertia causes it to bounce and overextend itself. Then it re-compresses, but will again travel too far. The spring continues to bounce at its natural frequency until all of the energy originally put into the spring is used.If the struts or shock absorbers are worn and the vehicle meets a bump in the road, the vehicle will bounce at the frequency of the suspension until the energy of the bump is used up. This may allow the tires to lose contact with the road.Struts and shock absorbers that are in good condition will allow the suspension to oscillate through one or two diminishing cycles, limiting or damping excessive movement, and maintaining vertical loads placed upon the tires. This helps keep the tires in contact with the road.By controlling spring and suspension movement, components such as tie rods will operate within their design range and, while the vehicle is in motion, dynamic wheel alignment will be maintained.SPRING DESIGNSBefore discussing spring design, it is important to understand sprung and unsprung weight. Sprung weight is the weight supported by the springs. For example, the vehicle's body, transmission, frame, and motor would be sprung weight. Unsprung weight is the weight that is not carried by springs, such as the tires, wheels, and brake assemblies.The springs allow the frame and vehicle to ride undisturbed while the suspension and tires follow the road surface. Reducing unsprung weight will provide less road shock. A high sprung weight along with a low unsprung weight provides improved ride and also improved tire traction.There are four major spring designs in use today: coil, leaf, torsion bar, and air.Coil SpringsThe most commonly used spring is the coil spring. The coil spring is a length of round spring steel rod that is wound into a coil. Unlike leaf springs, conventional coil springs do not develop inter-leaf friction. Therefore, they provide a smoother ride.The diameter and length of the wire determine the strength of a spring. Increasing the wire diameter will produce a stronger spring, while increasing its length will make it more flexible.Spring rate, sometimes referred to as deflection rate, is used to measure spring strength. It is the amount of weight that is required to compress the spring 1 inch. For example: If it takes 100 lbs. to compress a spring 1inch, it would take to 200 lbs. to compress the spring 2 inches.Some coil springs are made with a variable rate. This variable rate is accomplished by either constructing this spring from materials having different thickness or by winding the spring so the coil will progressively compress at a higher rate. Variable rate springs provide a lower spring rate under unloaded conditions offering a smoother ride, and a higher spring rate under loaded conditions, resulting in more support and control.Coil springs require no adjustment and for the most part are trouble-free. The most common failure is spring sag. Springs that have sagged below vehicle design height will change the alignment geometry. This can create tire wear, handling problems, and wear other suspension components. During suspension service it is very important that vehicle ride height be measured. Ride height measurements not within manufacturer’s specifications require replacement of springs.Leaf SpringsLeaf springs are designed two ways: multi-leaf and mono-leaf. The multi-leaf spring is made of several steel plates of different lengths stacked together. During normal operation, the spring compresses to absorb road shock. The leaf springs bend and slide on each other allowing suspension movement.An example of a mono-leaf spring is the tapered leaf spring. The leaf is thick in the middle and tapers toward the two ends. Many of these leaf springs are made of a composite material, while others are made of steel.In most cases leaf springs are used in pairs mounted longitudinally (front to back). However, there are an increasing number of vehicle manufacturers using a single transverse (side to side) mounted leaf spring.Torsion BarAnother type of spring is the torsion bar. The torsion bar is a straight or L shaped bar of spring steel. Most torsion bars are longitudinal, mounted solidly to the frame at one end and connected to a moving part of the suspension at the other. Torsion bars may also be transverse mounted. During suspension movement, the torsion bar will twist, providing spring action.Air SpringsThe air spring is another type of spring that is becoming more popular on passenger cars, light trucks, and heavy trucks. The air spring is a rubber cylinder filled with compressed air. A piston attached to the lower control arm moves up and down with the lower control arm. This causes the compressed air to provide spring action. If the vehicle load changes, a valve at the top of the airbag opens to add or release air from the air spring. An onboard compressor supplies air.Tires as SpringsAn often-overlooked spring is the tire. Tires are air springs that support the total weight of the vehicle. The air spring action of the tire is very important to the ride quality and safe handling of the vehicle. As a matter of fact, tires may be viewed as the number-one ride control component. Tire size, construction, compound and inflation are very important to the ride quality of the vehicle.STRUT MOUNTDESIGNStrut mounts are vehicle specific, and there are numerous designs in use today on both front and rear suspension systems. The three most common designs are inner plate, center sleeve, and spacer bushing.The Inner Plate Design used by General Motors and some Ford applications feature an inner plate encased in molded rubber surrounded by upper and lower surface plates. The inner plate is designed so the strut piston rod cannot push through the upper or lower surface plate if the rubber core fails. This design generally does not require washers. Due to the fact that the upper and lower service plates mostly cover the rubber portion of the mount, it is difficult to see if the inner rubber bushing has failed. However, these components wear over time and with a thorough inspection a proper recommendation can be made. The bearing is located on the bottom of the strut mount and is not serviceable. Defective bearing will require replacement of the entire strut mount.The Center Sleeve Design used by Chrysler features a center sleeve that is molded to the rubber bushing. This design provides increased side to side stability.The strut stem extends through the center sleeve. Upper and lower retainer washers prevent the strut rod from pushing through the strut mount. The bearing is a separate component from the strut mount. If inspection reveals cracks or tears in the rubber bushing, replacement is required. If the bearing is found to be defective it can be replaced separately.The Spacer Bushing Design used by V olkswagen, Toyota, Mazda, Mitsubishi, and early Chrysler vehicles feature center positioning of the bearing and a separate inner bushing instead of a molded inner sleeve. The operation is similar to the style we just discussed except the bearing is pressed in the strut mount. The bearings, washer, and the upper plate retain the strut rod. If the rubber bushing is cracked, torn, or the bearing is binding or seized, the strut mount requires replacement.ANTI-SWAY BARSAnother important component of a suspension system is the anti-sway bar. This device is used along with shock absorbers to provide additional stability. The anti-sway bar is simply a metal rod connected to both of the lower control arms. When the suspension at one wheel moves up and down the anti-sway bar transfers the movement to the other wheel. In this way the sway bar creates a more level ride and reduces vehicle sway or lean during cornering.Depending of the anti-sway bar thickness and design, it can provide as much as 15% reduction in the amount of vehicle roll or sway during cornering.BUSHINGSBushings are used in many locations on the vehicle suspension system. Most bushings are made with natural rubber. However, in some cases, urethane compounds may be used. Bushings made of natural rubber offer high tensile (tear) strength and excellent stability at low temperatures. Natural rubber is an elastomeric material. Elastomeric refers to the natural elastic nature of rubber to allow movement of the bushing in a twisting plane. Movement is controlled by the design of the rubber element. Natural rubber requires no lubrication, isolates minor vibration, reduces transmitted road shock, operates noise free, and offers a large degree of bushing compliance. Bushing compliance permits movement without binding. Natural rubber resists permanent deflections, is water resistant and very durable. In addition, natural rubber offers high load carrying capabilities.As with all suspension system components, control arm bushings are dynamic components, meaning that they operate while the vehicle is in motion. Control armsact as locators because they hold the position of the suspension in relation to the chassis. They are attached to the vehicle frame with rubber elastomeric bushings. During suspension travel, the control arm bushings provide a pivot point for the control arm. They also maintain the lateral and vertical location of the control arm pivot points, maintain dynamic wheel alignment, reduce transmitted noise, road shock, and vibration, while providing resistance to suspension movement.During suspension travel the rubber portion of the bushing must twist to allow control arm movement. Control arm bushings that are in good condition act as a spring; that is, the rubber will spring back to the position from which it started. This twisting action of the rubber will provide resistance to suspension movement.As previously stated, control arm bushings are dynamic suspension components. As the control arm travels through jounce and rebound, the rubber portion of the bushing will twist and stretch. This action transfers energy into the bushing and generates heat.Excessive heat tends to harden the rubber. As the rubber bushing hardens, it tends to crack, break, and then disintegrate. Its temperature determines the life of a rubber bushing. Rough road conditions and/or defective shock absorbers or struts will allow excessive suspension movement creating more heat, which shortens the life of the bushings.Rubber bushings must not be lubricated with petroleum-based oil. A petroleum-based product will destroy the bushings. Instead, use a special tire rubber lubricant or a silicone based lubricant.Worn suspension bushings allow the control arm to change positions. This results in driveline vibration (primarily rear wheel drive rear control arm bushings), dynamic alignment angle changes, tire wear, and handling problems. Control arm bushing wear (looseness) will create a clunking sound while driving over rough roads.悬架系统的基本元件当我们复习悬架系统组成时，我记得它们是怎么工作的，一辆行驶车的汽车，更应该说是车轮的转动。
悬架系统的基本原理外文文献翻译、中英文翻译、外文翻译
悬架系统的基本原理外文文献翻译、中英文翻译、外文翻译悬架系统的基本原理悬架系统虽然不是汽车运行不可或缺的部件，但有了它人们可以获得更佳的驾驶感受。
简单来说，它是车身与路面之间的桥梁。
悬架的行程涉及到悬浮于车轮之上的车架，传动系的相对位置。
就像横跨于旧金山海湾之上的金门大桥，它连接了海湾两岸。
去掉汽车上的悬架就像是你做一次冷水潜泳通过海湾一样，你可以平安的渡过整个秋天，但会疼痛会持续几周。
想想滑板吧！它直接接触路面，你可以感受到每一块砖，裂隙及其撞击。
这简直就是一种令人全身都为之震颤的体验。
当轮子滑过路面时，就会在此产生震动、冲击，这种震动的旅程是对你的身体和勇气的检验。
如果你没感到随时都有被掀之势，那么你或许会乐在其中吧！这就是你会在没有悬架的汽车上将会体验到的。
汽车的悬架分为两种基本类型：整体和独立悬架。
整体悬架（也叫刚性梁、刚性轴）是联接车辆上下两部分的一种主要形式。
一如其名，它是用一根金属材料（一般是轴）来连接两侧车轮的。
钢板弹簧在车架之间起到缓冲作用；在两半轴中间装有差速器，允许两侧的轮子以不同的角速度旋转。
整体式悬架的车辆在行进中，由于两侧的车轮共用一根轴，因此当某一侧车轮跳动时，另一侧也会随之运动。
它们的反馈结果就像是一个整体。
可以想象到，这不可能有舒适的驾驶体验。
虽然可以借助于弹簧来衰减猛烈的震动，但仍然存在较强的震动。
那么既然如此，为什么还要使用这种悬架呢？第一，它很坚固，由于采用了一体化的结构，定轴式悬架系统具有着其他方式悬架不可替代的承载能力。
它们经常应用于行驶于较差路况的车辆。
你可以在卡车和重载车辆上见到它。
一种由固定轴式悬架变形系统叫做TIB悬架系统（或叫半固定轴式）。
在这种结构中，有两根刚性轴而非一根。
这种设计可兼得较大的刚性和较好的韧性，通常用于轻卡的前悬。
另一种常见的悬架系统是独立悬架，它由两个独立的“桥”连接车轮。
这种结构可以提供最舒适的乘坐环境，因此多用于乘用车、小型货车和其他小型车辆。
外文翻译--汽车悬架工作原理
外文翻译--汽车悬架工作原理附录3英文原文How Car Suspensions WorkBy William HarrisUniversity of MichiganWhen people think of automobile performance, they normally think of horsepower, torque and zero-to-60 acceleration. But all of the power generated by a piston engine is useless if the driver can't control the car. That's why automobile engineers turned their attention to the suspension system almost as soon as they had mastered the four-stroke internal combustion engine.Photo courtesy Honda Motor Co., Ltd.Double-wishbone suspension on Honda Accord 2005 CoupeThe job of a car suspension is to maximize the friction between the tires and the road surface, to provide steering stability with good handling and to ensure the comfort of the passengers. In this article, we'll explore how car suspensions work, how they've evolved over the years and where the design of suspensions is headed in the future.Vehicle DynamicsIf a road were perfectly flat, with no irregularities, suspensions wouldn't be necessary. But roads are far from flat. Even freshly paved highways have subtle imperfections that can interact with the wheels of a car. It's these imperfections that apply forces to the wheels. According to Newton's laws of motion, all forces have both magnitude and direction. A bump in the road causes the wheel to move up and down perpendicular to the road surface. The magnitude, of course, depends on whether the wheel is striking a giant bump or a tiny speck. Either way, the car wheel experiences a vertical acceleration as it passes over an imperfection.Without an intervening structure, all of wheel's vertical energy is transferred to the frame, which moves in the same direction. In such a situation, the wheels can lose contact with the road completely. Then, under the downward force of gravity, the wheels can slam back into the road surface. What you need is a system that will absorb the energy of the vertically accelerated wheel, allowing the frame and body to ride undisturbed while the wheels follow bumps in the road.The study of the forces at work on a moving car is called vehicle dynamics, and you need to understand some of these concepts in order to appreciatewhy a suspension is necessary in the first place. Most automobile engineers consider the dynamics of a moving car from two perspectives:Ride - a car's ability to smooth out a bumpy roadHandling - a car's ability to safely accelerate, brake and cornerThese two characteristics can be further described in three important principles - road isolation, road holding and cornering. The table below describes these principles and how engineers attempt to solve the challenges unique to each.A car's suspension, with its various components, provides all of the solutions described.Let's look at the parts of a typical suspension.The ChassisThe suspension of a car is actually part of the chassis, which comprises all of the important systems located beneath the car's body.These systems include:The frame - structural, load-carrying component that supports the car's engine and body, which are in turn supported by the suspensionThe suspension system - setup that supports weight, absorbs and dampens shock and helps maintain tire contactThe steering system - mechanism that enables the driver to guide and direct the vehicleThe tires and wheels - components that make vehicle motion possible by way of grip and/or friction with the roadSo the suspension is just one of the major systems in any vehicle.With this big-picture overview in mind, it's time to look at the three fundamental components of any suspension: springs, dampers and anti-sway bars. SpringsToday's springing systems are based on one of four basic designs: Coil springs This is the most common type of spring and is, in essence, aheavy-duty torsion bar coiled around an axis. Coil springs compress and expand to absorb the motion of the wheels.Leaf springs - This type of spring consists of several layers of metal (called "leaves") bound together to act as a single unit. Leaf springs were first used on horse-drawn carriages and were found on most American automobiles until 1985. They are still used today on most trucks and heavy-duty vehicles.Torsion bars - Torsion bars use the twisting properties of a steel bar to provide coil-spring-like performance. This is how they work: One end of a bar is anchored to the vehicle frame. The other end is attached to a wishbone, which acts like a lever that moves perpendicular to the torsion bar. When the wheel hits a bump, vertical motion is transferred to the wishbone and then, through the levering action, to the torsion bar. The torsion bar then twists along its axis to provide the spring force. European carmakers used this system extensively, as did Packard and Chrysler in the United States, through the 1950s and 1960s.Air springs - Air springs, which consist of a cylindrical chamber of air positioned between the wheel and the car's body, use the compressive qualities of air to absorb wheel vibrations. The concept is actually more than a century old and could be found on horse-drawn buggies. Air springs from this era were made from air-filled, leather diaphragms, much like a bellows; they were replaced with molded-rubber air springs in the 1930s. Based on where springs are located on a car -- i.e., between the wheels and the frame -- engineers often find it convenient to talk about the sprung mass and the unsprung mass.Springs: Sprung and Unsprung MassThe sprung mass is the mass of the vehicle supported on the springs, while the unsprung mass is loosely defined as the mass between the road and the suspension springs. The stiffness of the springs affects how the sprung mass responds while the car is being driven. Loosely sprung cars, such asluxury cars (think Lincoln Town Car), can swallow bumps and provide a super-smooth ride; however, such a car is prone to dive and squat during braking and acceleration and tends to experience body sway or roll during cornering. Tightly sprung cars, such as sports cars (think Mazda Miata), are less forgiving on bumpy roads, but they minimize body motion well, which means they can be driven aggressively, even around corners.So, while springs by themselves seem like simple devices, designing and implementing them on a car to balance passenger comfort with handling is a complex task. And to make matters more complex, springs alone can't provide a perfectly smooth ride. Why? Because springs are great at absorbing energy, but not so good at dissipating it. Other structures, known as dampers, are required to do this.Dampers: Shock AbsorbersUnless a dampening structure is present, a car spring will extend and release the energy it absorbs from a bump at an uncontrolled rate. The spring will continue to bounce at its natural frequency until all of the energy originally put into it is used up. A suspension built on springs alone would make for an extremely bouncy ride and, depending on the terrain, an uncontrollable car.Enter the shock absorber, or snubber, a device that controls unwanted spring motion through a process known as dampening. Shock absorbers slow down and reduce the magnitude of vibratory motions by turning the kinetic energy of suspension movement into heat energy that can be dissipated through hydraulic fluid. To understand how this works, it's best to look inside a shock absorber to see its structure and function.附录4英文翻译汽车悬架工作原理William Harris密歇根大学当人们想到汽车性能时，他们通常想起的是马力，扭矩，0到60加速时间。
汽车悬架的发展历程外文文献翻译、中英文翻译、外文翻译
The development of automobile suspensionAutomobile suspension system is a connecting structure system between the body and frame and wheels, and the structural system includes shock absorbers, suspension springs, anti roll bars, suspension side beam, lower control arm, longitudinal bar, steering knuckle arm, rubber bushing and connecting rod etc.. When the car on the road because of the ground change by the vibration and impact, the impact strength of one part by tire absorption, but mostly rely on suspension tire and the body to absorb. In the running process of the automobile suspension, the role is to connect the axle and the frame flexibility, slow moving vehicle impact force caused by uneven pavement, ensure the ride comfort and the goods, due to the rapid decay caused by the vibration of elastic system, vertical, longitudinal and lateral transfer to force and torque, and play a leading role. The wheel according to a certain trajectory relative to body movement. Suspension is one of the most important parts of modern automobile. The typical suspension structure is made up of elastic element, guide mechanism and shock absorber, etc., and there are buffer blocks, transverse stabilizer bars and so on. The elastic element is composed of a steel plate spring, an air spring, a spiral spring and a torsion bar spring, etc. the modern car suspension adopts a spiral spring and a torsion bar spring.Types and working principle of suspensionAccording to the suspension damping and stiffness changes with the change of driving conditions, can be divided into passive suspension, semi-active suspension and active suspension, semi-active suspension can also be divided into two types of damping and variable type. The traditional system of suspension stiffness and damping coefficient is selected according to the experience design and optimization design method, once selected, in the course of the vehicle, it can not be adjusted, so the damping performance limits further enhance, the suspension has become passive suspension. In order to overcome the defects of passive suspension, the concept of active suspension was proposed in 1960s, which is composed of active or passive components. It is a closed loop control system, according to the movement of the vehicle and the state of the road to take the initiative to respond to restrain the movement of the body, so that the suspension is always in the best state of shock.Therefore, the characteristics of active suspension is to adapt to the changes of the external input or the vehicle itself. So the system must be active. Semi active suspension is composed of passive but controllable damping elements. In the vehicle suspension, in addition to absorbing and storing energy, the elastic element also has to bear the weight and the load of the vehicle body. Therefore, the semi-active suspension does not consider changing the stiffness of the suspension. Because of the semi active suspension structure is simple, in the work, almost does not consume the vehicle power, but also can get similar performance with the active suspension, it is widely used. Due to random road input, control of vehicle suspension damping belongs to adaptive control system is designed, changes occur in a wide range of input or interference, adaptive environment, adjusting the system parameters, so that the output can be controlled effectively, meet the design requirements. It is different from the general feedback control system because it deals with the feedback information with "uncertainty". The adaptive control system according to the principle of different, can be divided into tuning regulator and model reference adaptive control system of two categories, because it is difficult to establish a precise "vehicle bottom" system model, the active suspension, the use of self correction regulator. Although there are many kinds of modern automobile, the structure difference is big, but it is generally composed of elastic element, damping element and guiding component. The working principle is that when the automobile tire is impacted, the elastic element is used for buffering the impact to prevent damage to the automobile components and personnel. However, the elastic parts will be affected by the growth time of sustained vibration, easy to make the driver fatigue. Therefore, the vibration damping elements should be quickly damped vibration. When the wheel is hit by the impact, it should be consistent with the trajectory of certain requirements, otherwise it will reduce the ride comfort and handling stability of the vehicle. The direction of the steering component must be controlled at the same time.The history and present situation of suspensionIn the carriage appeared, in order to ride more comfortable, humans began to ride the suspension of a leaf spring tireless exploration. In 1776, the leaf spring of the carriage was patented, and it was used until 1930s. After the birth of the car, with the in-depth study of thesuspension, the torsion spring, gas spring, rubber spring, leaf spring, etc.. In 1934, the world's first passive suspension composed of helical springs. The parameters of the passive suspension are determined according to the experience or the method of optimal design. It is a series of road compromise, it is difficult to adapt to a variety of complex road conditions, the effect of poor damping. In order to overcome this defect, the nonlinear stiffness spring and the adjustment of the height of the body are adopted. Although the results are satisfactory, the disadvantages of passive suspension can not be eliminated. The passive suspension is mainly used in low-grade cars, the front suspension of modern cars generally use the Mcpherson suspension with stabilizer bar, choose more after the suspension, the main composite longitudinal swing arm suspension and multi link suspension. Semi active suspension research began in 1973, first proposed by D.A.Crosby and D.C.Karnopp. Semi active suspension is mainly used to change the damping of suspension. The working principle is as follows: according to the control law of the spring, the damping force or stiffness of the spring can be adjusted according to the feedback signal of the spring mass relative to the wheel speed response and acceleration response. The semi-active suspension is similar to the passive suspension, but its damping or stiffness coefficient can be adjusted according to the running state, which is similar to that of the active suspension. A type of semi active suspension damping is divided into several stages, the damping level by the driver according to the "road" or by the sensor signal automatic selection; stepless semi-active suspension based on road conditions and vehicle driving state of suspension within a few milliseconds from the minimum to the stepless speed regulation. Due to the relatively simple structure of the semi-active suspension, the work does not need to consume the power of the vehicle, and can obtain the same performance with the active suspension, has a broad space for development. With the continuous development of road traffic, vehicle speed has been greatly improved, the passive suspension has gradually become the bottleneck of improving the performance of vehicle, so people can develop both comfort and handling stability of active suspension. The concept of active suspension is the first proposed in the suspension design of General Motors Corporation in 1954. On the basis of the passive suspension, it can increase the stiffness and damping of the control device, so that the suspension of the car on any road to maintain thebest running state. The control device is composed of measuring system, feedback control system and energy system. In 1980s, the world's leading automobile companies and manufacturers competing to develop and develop this suspension. Mercedes Benz, V olvo, Lotts, TOYOTA, etc. in the car on a more successful test. Equipped with active suspension of the car, in the bad road high speed, the body is very stable, the tire noise is small, steering and braking body to maintain the level of. The utility model is characterized in that the ride is very comfortable, but the structure is complex, the energy consumption is high, the cost is high, and the reliability is different.Due to various reasons, most of China's automotive passive suspension. In the study of semi-active and active suspension started late, with a large gap between foreign countries. In the western developed countries, semi active suspension in the late 1980s tends to mature, Ford Motor Co and Nissan first in the car application, and achieved good results. Although the active suspension has been put forward earlier, it is difficult to make a big breakthrough because of its complicated control and many subjects. Into 1990s, throwing only applies to the large amount of luxury cars. There is no report of domestic automotive products using this technology, only a few research institutions such as Beijing Institute of Technology and Tongji University to study the active suspension.Development trend of suspensionDue to the requirements of ride comfort and handling stability, a safe, intelligent and clean green intelligent suspension will be the future development trend of automobile suspension. Passive suspension is a traditional mechanical mechanism, stiffness and damping are not adjustable, according to the theory of random vibration, it can only ensure that the specific road conditions to achieve better results. However, its theory is mature, simple structure, reliable performance, relatively low cost and does not require additional energy, which is the most widely used. In our country, there is still a high research value. Study on passive suspension performance mainly in three aspects: through analyzing the stress of the car after the establishment of mathematical model, the optimal parameters and then use the computer simulation technology or finite element method for suspension; damper of variable stiffness spring and variable damping suspension, make good operation in most of the roadstudy; guiding mechanism, make the car suspension to meet the comfortUnder the premise, the stability has improved greatly. The research of semi-active suspension is focused on two aspects: the research of execution strategy and the research of actuator. There are two kinds of damping adjustable shock absorber, one is to adjust the damping by changing the size of the orifice. The size of the throttle hole in general through the solenoid valve or stepper motor for a level or stepless adjustment, this method is more expensive, complex structure. The damping coefficient can be changed by changing the viscosity of the damping fluid, which has the characteristics of simple structure, low cost, no noise and shock. The research of active suspension is also focused on two aspects: reliability; actuator. The active suspension with a large number of sensors, MCU, input and output circuit and the interface, because of more components, reduces the reliability of the suspension, therefore, increase the degree of integration of elements, is an impassable stage. The actuator is mainly used to replace the hydraulic components of electric devices. The linear servo motor and permanent magnet DC linear servo motor in electric power system have many advantages, which will replace the hydraulic actuator in the future. Based on the principle of electromagnetic energy storage and the self tuning controller of parameter estimation, a high performance and low power electromagnetic active adaptive suspension can be designed. With the development of the traffic, the highway is improving gradually, and the speed of the car is faster and faster. The automobile suspension system to support force, the road acting on the wheel longitudinal force and lateral force and the reaction force caused by the torque is transmitted to the frame, in order to ensure the normal running of the vehicle, therefore has a crucial influence on the vehicle driving vehicle suspension system, dynamic simulation of the automobile suspension system is very high status in vehicle design and development. In the field of automobile engineering, simulation software can avoid duplication of manufacturing parts and prototype in product development process, resources, reduce the waste of time and money, a study on the power can be better kinematics in automotive engineering field using simulation software. Foreign countries have developed IMP, ADAMS and DAMN simulation software for the field of automotive kinematics.ConclusionWith Solidworks, Pro/E, CATIA, UG, ADAMS, ANSYS and other CAD/CAE software development, plays a key role in the research and development of automobile suspension, through finite element method, computer simulation technology, reduce the enterprise cost of research and development of computer optimization design method, shorten the development cycle. Generally speaking, the active suspension has good damping effect and superior performance, and solves the contradiction of ride comfort and handling stability. But the component cost is higher, work needs more energy, vehicle quality also increased, so the active suspension will greatly increase the cost and energy consumption; the damping performance of the semi-active suspension close to active suspension, steering stability is better than passive suspension. It is the only way for the development of semi-active suspension that the performance is reliable, the adjustable damping damper and the simple and effective control strategy. The performance of passive suspension is the worst, but it has the lowest cost and no need to consume energy. Passive suspension in a certain period of time will be the most widely used suspension system, by further optimizing the suspension structure and parameters can continue to improve the suspension performance.汽车悬架的发展历程汽车的悬架系统是指车身、车架和车轮之间的一个连接结构系统，而这个结构系统包含了避震器、悬架弹簧、防倾杆、悬吊副梁、下控臂、纵向杆、转向节臂、橡皮衬套和连杆等部件。
中英文文献翻译—悬架与转向系统悬架与转向系统的基本组成与类型
中英文文献翻译—悬架与转向系统悬架与转向系统的基本组成与类型附录附录ABasic Parts and Types of the Suspension and Steering Systems Suspension SystemIf a vehicle's axles were bolted directly to its frame or body, every rough spot in the road would transmit a jarring force throughout the vehicle. Riding would be uncomfortable, and handling at freeway speeds would be impossible. The fact that the modern vehicle rides and handles well is a direct result of a suspension system.Even though the tires and wheels must follow the road contour, the body should be influenced as little as possible [1]. The purpose of any suspension system is to allow the body of the vehicle to travel forward with a minimum amount of up-and-down movement. The suspension should also permit the vehicle to make turns without excessive body roll or tire skidding.Suspension System ComponentsVehicle FrameA vehicle's frame or body must form a rigid structural foundation and provide solid anchorage points for the suspension system. There are two types of vehicle construction in common use today: body-over-frame construction, which uses a separate steel frame to which the body is bolted at various points and unibody construction, in which the body sections serve as structural members. Unibody construction is the most common, but body-over-frame construction is still used on pickup trucks and large cars.SpringsThe springs are the most obvious part of the suspension system. Every vehicle has a spring of some kind between the frame or body and the axles. There are three types of springs in general use today: leaf spring, coil spring, and torsion bar. Two different types of springs can be used on one vehicle. Air springs were once used in place of the other types of springs, but are now obsolete. Many modern vehicles have air-operated suspensions, but they are used to supplement the springs.Shock AbsorbersWhen the vehicle is traveling forward on a level surface and the wheels strike a bump, the spring is rapidly compressed (coil springs) or twisted (leaf springsand torsion bars). The spring will attempt to return to its normal loaded length. In so doing, it will rebound, causing the body of the vehicle to be lifted. Since the spring has stored energy, it will rebound past its normal length. The upward movement of the vehicle also assists in rebounding past the spring's normal length.The weight of the vehicle then pushes the spring down after the spring rebounds. The weight of the vehicle will push the spring down, but since the vehicle is traveling downward, the energy built up by the descending body will push the spring below its normal loaded height. This causes the spring to rebound again. This process, called spring oscillation, gradually diminishes until the vehicle is finally still. Spring oscillation can affect handling and ride quality and must be controlled.Air Shock AbsorbersSome suspension systems incorporate two adjustable air shock absorbers that are attached to the rear suspension andconnected to an air valve with flexible tubing.Air operated shock absorbers have hydraulic dampening systems which operate in the same manner as those on conventional shocks. In addition, they contain a sealed air chamber, which is acted on by pressure from a height control sensor. Varying the pressure to the air chamber causes the air shock to increase or decrease its length or operating range.Air pressure is delivered to the air shocks through plastic tubing. The tubing connects the shocks to an air valve. Air pressure for raising the shocks is generally obtained from an outside source, such as a service station compressor, and is admitted through the air valve. To deplete the shocks of unwanted air (lower vehicle curb height), the air valve core is depressed, allowing air to escape.Control ArmsAll vehicles have either control arms or struts to keep the wheel assembly in the proper position. The control arms and struts allow the wheel to move up and down while preventing it from moving in any other direction. The wheel will tend to move in undesirable directions whenever the vehicle is accelerated, braked, or turned. Vehicle suspensions may have control arms only or a combination of control arms and struts.Types of the SuspensionFront Suspension SystemsAlmost all modern front suspension systems are independent. With anindependent suspension, each front wheel is free to move up and down with a minimum effect on the other wheel. In an independent suspension system, there is also far less twisting motion imposed on the frame than in a system with a solid axle.Nevertheless, a few off-road, four wheel drive vehicles and large trucks continue to use a solid axle front suspension. The two major types of independent front suspension are the conventional front suspension and the MacPherson strut front suspension.Conventional Front Suspension In the conventional front suspension system, one or two control arms are used at each wheel. In most systems, the coil springs are mounted between the vehicle's frame and the lower control arm. In older systems, coil springs are mounted between the upper control arm and vehicle body. In a torsion bar front suspension system, the lower arm moves upward, it twists the torsion bar.Coil Spring Front Suspension Fig.11-1 shows a typical independent front suspension that uses rubber bushing control arm pivots. The top of the coil spring rests in a cup-like spot against the frame (unshown). The bottom of the coil spring is supported by a pad on the lower control arm. The top of each shock absorber is fastened to the frame; the bottom is attached to the lower control arm.Torsion Bar Front Suspension A torsion bar is located on each side of the frame in the front of the vehicle. The lower control arm is attached to the free end of the torsion bar. When the wheel is driven upward, the lower control arm moves upward, twisting the long spring steel bar.Macpherson Strut Front Suspension Most modern vehicles, especially those with front-wheel drive, use the MacPherson strut front suspension systems, Fig.11-2. Note that the MacPherson strut contains a coil spring, which is mounted on top of the heavy strut-and-pedestal assembly. The entire MacPherson strut assembly is attached to the steering knuckle at the lower part ofthe pedestal. The bottom of the MacPherson strut assembly is attached to the single control arm through a ball joint.The entire strut assembly turns when the wheel is turned. A bearing or thrust plate at the top of the strut assembly allows relative movement between the assembly and the vehicle body. The ball joint allows the strut assembly to turn in relation to the control arm. The strut contains a damper, which operates in the same manner as a conventional shock absorber. Most damper assemblies have a protective cover that keeps dirt and water away from the damper piston rod.The advantage of the MacPherson strut is its compact design, which allows more room for service on small car bodies.Solid Axle Front Suspension The use of the solid axle front suspension (or dependent suspension) is generally confined to trucks and off-road vehicles. This system uses a solid steel dead.Rear Suspension SystemsRear suspensions on vehicles with a solid rear axle housing generally utilize coil springs or leaf springs. When the vehicle has an independent rear suspension system, coil springs, MacPherson struts, a single transverse leaf spring, or even torsion bars can be used.Steering SystemThe steering system is designed to allow the driver to move the front wheels to the right or left with a minimum of effort and without excessive movement of the steering wheel. Although the driver can move the wheels easily, road shocks are not transmitted to the driver. This absence of road shock transfer is referred to as the nonreversible feature of steering systems.The basic steering system can be divided into three main assemblies:The spindle and steering arm assemblies.The linkage assembly connecting the steering arms and steering gear.The steering wheel, steering shaft, and steering gear assembly.Steering GearThe steering gear is designed to multiply the driver's turning torque so the front wheels may be turned easily. When the parallelogram linkage is used, the torque developed by the driver is multiplied through gears and is then transmitted to the wheel spindle assemblies through the linkage. On the rack-and-pinion steering system, the steering shaft is connected directly to the pinion shaft. Turning the pinion moves the rack section, witch moves the linkage. Late-model vehicles use either manual steering gears or power steering gears.There are three types of the steering gears in use: recirculating ball steering gear, worm-and-roller steering gear and rack-and-pinion steering gear.Power SteeringPower steering is designed to reduce the effort needed to turn the steering wheel by utilizing hydraulic pressure to bolster (strengthen) the normal torque developed bythe steering gear. Power steering systems should ease steering wheel manipulation and, at the same time, offer enough resistance so that the driver can retain some road feel. Power steering is used with both conventional and rack-and-pinion systems (Fig.11-3).The self-contained steering gear contains the control valve mechanism, the power piston, and the gears. Pressure developed by the unit is applied to the pitman shaftThe power rack-and-pinion steering system also uses a rotary control valve that directs the hydraulic fluid from the pump to either side of the rack piston. An overall view of this setup is shown in Figure 11-3. Steering wheel motion is transferred to the pinion. From there, it is sent through the pinion teeth, which are in mesh with the rack teeth. The integral rack piston, which is connected to the rack, changes hydraulic pressure to a linear force (back and forth movement in a straight line). This, in turn, moves the rack in a right or left direction. The force is transmitted by the inner and outer tie rods to the steering knuckles, which, in turn, move the wheels.附录B悬架与转向系统悬架与转向系统的基本组成与类型1.悬架系统如果将一辆汽车的车桥直接固定到车架或车身上，道路上的每个凹凸不平的点都会将一个冲击力传递给车辆。
- 1、下载文档前请自行甄别文档内容的完整性，平台不提供额外的编辑、内容补充、找答案等附加服务。
- 2、"仅部分预览"的文档,不可在线预览部分如存在完整性等问题,可反馈申请退款(可完整预览的文档不适用该条件!)。
- 3、如文档侵犯您的权益，请联系客服反馈,我们会尽快为您处理(人工客服工作时间：9:00-18:30)。
附录Ⅰ：外文资料Automotive Suspension System Overview The impact of the Vehicle in many aspects, Suspension plays a very important role .The components of the suspension system perform six basic functions:1.Maintain correct vehicle ride height.2.Reduce the effect of shock forces.3.Maintain correct wheel alignment.4.Support vehicle weight.5.Keep the tires in contact with the road.6.Control the vehicle’s direction of travel.Most suspension systems have the same basic parts and operate basically in the same way. They differ, however, in the way the parts are arranged. The vehicle wheel is attached to a steering knuckle. The steering knuckle is attached to the vehicle frame by two control arms, which are mounted so they can pivot up and down. A coil spring is mounted between the lower control arm and the frame.When the wheel rolls over a bump, the control arms move up and compress the spring. When the wheel rolls into a dip, the control arms move down and the springs expand. The spring force brings the control arms and the wheel back into the normal position as soon as the wheel is on flat pavement. The idea is to allow the wheel to move up and down while the frame, body, and passengers stay smooth and level. The unequal length control arm or short, long arm (SLA) suspension system has been common on American vehicles for many years. Because each wheel is independently connected to the frame by a steering knuckle, ball joint assemblies, and upper and lower control arms, the system is often described as an independent suspension. The short, long arm suspension system gets its name from the use of two control arms from the frame to the steering knuckle and wheel assembly. The two control arms are of unequal length with a long control arm on the bottom and a short control arm on the top. The control arms are sometimes called A arms because in the top view they are shaped like the letter A.In the short, long arm suspension system, the upper control arm is attached to a cross shaft through two combination rubber and metal bushings. The cross shaft, in turn, is bolted to the frame. A ball joint, called the upper ball joint, is attached to the outer end of the upper arm and connects to the steering knuckle through a tapered stud held in position with a nut. The inner ends of the lower control arm have pressed-inbushings. Bolts, passing through the bushings, attach the arm to the frame. The lower ball joint is usually pressed into the control arm and connects to the steering knuckle through a tapered stud that is held in position with a nut. A ball joint is used on the control arms because it allows movement in more than one direction. It allows the up-and-down motion required as the wheels pass over dips and bumps. This type of joint also allows side-to-side motion as the wheels are turned back and forth for turns.For the upper and lower ball joint, the ball stud in the ball joint is a tapered stud at one end with a ball-shaped end. The ball end is supported in a similarly shaped housing called a socket. The shape of the housing allows the ball stud to turn around or move side to side. A plastic or sintered iron bearing is positioned between the ball and socket .The bearing allows the ball stud to turn in relation to the housing for steering. The tapered stud and nut hold the ball joint in position in the steering knuckle.There are four basic types of springs used in suspensions: coil, torsion bar, leaf spring, and air spring. The coil spring is the most popular type of spring in both front and rear suspension systems. It is simply a round bar of spring steel that is wound into the shape of a coil. Usually, the top and bottom coils are closer together than the middle coils.A coil spring is commonly used on the short, long arm suspension system. Some cars have the spring mounted from the frame to the upper control arm. In either case, the shock absorber is mounted through the center of the spring. Most short, long arm systems use a stabilizer bar between the two sides of the suspension. The sway bar connects both lower control arms to the frame crossmember. Movements affecting one wheel are partially transmitted to the opposite wheel through the frame to stabilize body roll. The sway bar is attached to the frame crossmember and lower control arms through rubber insulator bushings to reduce noise and vibrations. Sway bar end bushings and crossmember bushings are permanently installed on the sway bar.The advantages of the coil spring are its compactness, lack of moving parts, and excellent weight supporting characteristics.The disadvantage of a coil spring is its weakness in supporting side-to-side or lateral movement. When coil springs are used at the drive wheels, heavy traction bars or torque tubes are often required to maintain axle housing alignment.A number of vehicles use a torsion bar spring. It is a long, solid steel shaft that is anchored at one end to the suspensions control arm and at the other end to the vehicle's frame. Torsion is the twisting action that occurs in the bar when one end is twisted and the other end remains fixed. When a vertical impact on a wheel is transmitted through the control arm to the torsion bar, the bar twists to absorb theimpact. The bar's natural resistance to twisting quickly restores it to its original position, returning the wheel to the road.A torsion bar can store a significantly higher maximum amount of energy than either an equally stressed leaf or coil spring. The torsion offers important weight savings and it is adjustable. In addition, it requires significantly less space than a coil spring.The leaf spring is made of several layers of spring steel stacked one upon the other, Usually, there is one main leaf that uses spring eyes for locating and fastening the spring toe frame or underbody. Several other progressively shorter leaves are placed on the main leaf, and the assembly or leaf pack is held together in the middle by a center bolt and on the ends by rebound clips. Some spring packs use fiber. or plastic pads between leaves to reduce the internal leaf friction. Some vehicles use a single leaf instead of a buildup of multiple leaves. One manufacturer is using a leaf spring manufactured from a nonmetal composite. Leaf springs are usually arched so that the ends are higher than the center when viewed from the side.The leaf spring is usually mounted in three places. A bushing is installed in each of the spring eyes. A bolt through the bushing in the rear spring eye attaches the rear of the spring directly to the vehicle frame. A shackle assembly is attached to the front spring eye and bushing and is then mounted through a shackle bushing to the frame. The shackle assembly allows the leaf spring to pivot up and down. A pair of U-bolts and a tie plate are used to clamp the front or rear axle assembly to the leaf spring.The main advantage of leaf springs is their ability to control vehicle sway and lateral movement. For these reasons, leaf springs are often used on the rear suspension of rear drive vehicles.Many late-model luxury cars use air springs. The spring is essentially a rubber bag or bladder full of air. A piston is attached to the lower control arm. Movement of the lower control arm causes the piston to move into the air bladder and compress the air in the bladder. Air pressure is used to regulate how easy or hard the bladder can be compressed. The air bladder is usually connected to an air compressor, which regulates the action of the air spring based on road conditions.All suspension systems use a shock absorber at each wheel. When the coil, torsion bar, leaf spring, or air spring is deflected, it can oscillate (bounce up and down) uncontrollably, possibly causing the tires to lose contact with the road. This could cause the car to bounce up and down without any control. To prevent this from happening, shock absorbers are used, not to absorb shocks, but to control spring rate and dampen spring oscillations.The shock absorber is a hydraulic device. One end of the shock absorber is attached to a wheel assembly and the other end is attached to the vehicle frame. Shock absorber movement is limited by forcing fluid inside the shockabsorber through附录Ⅱ：中文翻译汽车悬架系统概述在影响汽车性能的众多方面中，悬架起着十分重要的作用。