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英文原文How Car Suspension WorkBy William HarrisUniversity of Michigan When people thinly 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 drier cant control the car. Thats why automobile engineers turned their attention to the suspension system almost as soon as they had mastered the four-Stroke internal combustion engine. Double-wishbone suspension on Honda Accord 2005 Coupe 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, well explore how car Suspensions work,how theyre evolved over the years and where the design of suspensions is headed in the future.1 .Vehicle Dynamics If a road were perfectly t1at, with no irregularities, suspensions wouldnt be necessary. But roads are far from t1at. Even freshly paved highways have subtle imperfections that can interact with the wheels of a car. Its these imperfections that apply forces to the wheels. According to Newtons 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 ca.r wheelexperiences a vertical acceleration as it passes over an imperfection. Without an intervening structure, all of wheels 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,wheels can slam back into the road surface. What you need is a system that 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 farces at work an a moving car is called vehicle dynamics, and you need to suspension is necessary of need to understand same of these concepts in order to appreciate why a necessary in the first place. Mast automobile engineers consider the moving car Pram two perspectives: 1) Ride-a cars ability to smooth out a bumpy road 2)Handling-a cars ability to safely accelerate, brake and corner These 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 cars suspension, with its various components, provides all of the Solutions described. 2. The Chassis System The suspension of a car is actually part of the chassis, which comprises all of the important systems located beneath the cars body.figure 2-1 ChassisThese systems include: 1) The frame-structural, load-carrying component that supports the cars engine and body, which are in turn supported by the suspension 2)The Suspension system-setup that supports weight, absorbs and dampens shock and helps maintain tire contact 3)The steering system-mechanism that enables the driver to guide and direct the vehicle 4) The tires and wheels-components that make vehicle motion possible by way of grip and/or friction with the road So the suspension is just one of the major systems in any vehicle. With this big-picture overview in mind, its time to look at the three fundamental components of any suspension: springs, dampers and anti-sway bars.3 .springs Todays springing systems are based on one of four basic design:1)Coil spring-This is the mast common type of spring and is, in essence, a heavy-duty torsion barcoiled around an axis. Coil springs compress and expand to absorb the motion of the wheels.2)Leaf spring-This type of spring consists of several layers of metal (calledleaves) bound together to act as a single unit. Leaf springs were first used on horse-drawn carriages and were found an 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 Gar 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 i5 attached to a wishbone, which acts like a lever that mares 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 farce. European caretakers used this system extensively, as did Packard and Chrysler in the UnitedStates, through the 1950s and 1960s.4)Air springs-Air Springs, which consist of a cylindrical chamber of air positioned between the wheel and the cars body, use the compres5ire qualities of air to absorb wheel vibrations. The concept is actually more than a century old and could be found an 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 Mass The sprung mass is the mass of the vehicle supported an 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 Taws Card, can Swallow bumps and provide a super-smooth ride; however, such a car is prune to dive and squat during braking and acceleration and tends to experience body away 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 cant provide a perfectly smooth ride.W hy? 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 .Shack Absorbers Unless 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 an springs alone would make for an extremely bouncy ride and,depending an the terrain, an uncontrollable car. Enter the shack 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 lie dissipated through hydraulic fluid. To understand how this works, its best to look inside a shack 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 springy 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 leak through 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 world 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 mare resistance during its extension cycle than its compression cycle. With that in mind,the compression cycle controls the motion of the vehicles 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 shacks to adjust to road conditions and to central 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 two jobs-basically a shock absorber mounted inside a coil spring. Struts perform:They proride a dampening function like shack absorbers, and they provide structural support for the vehicle suspension. That means struts deliver a hit more than shock absorbers, which dont support vehicle weight-they only control the speed at which weight is transferred in a car not the weight itself. figure 6-1 Common strut design 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 tires ability to grip the road, as well as handling and braking performance.7.Anti-sway Bars Anti一sway bars (also known as anti-roll bars) are used slang 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 maven up and dawn, 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.Far this reason, almost all cars today are fitted with anti一sway bars as standard equipment, although if theyre not, kits make it easy to install the bars at any time.8.The Future of Car Suspension While there have been enhancements and improvements to both springs and shock absorbers, the basic deign of car suspensions has not undergone a significant evolution over the years. But all of thats about to change with the introduction of a brand-new suspension design conceived by Bole-the same 13ose known for its innovations in acoustic technologies. Some experts are going so far as to say that the Bole suspension is the biggest advance in automobile suspensions since the introduction of an all-independent design.figure 8-1 Suspension Front Modu1e How does it work? The Base system uses a linear electromagnetic motor (LEMA )at each wheel in lieu of a conventional shock-and一spring setup. Amplifiers provide electricity to the motors in such a way that their power 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 LE1VI can extend and compress at a much greater speed, virtually eliminating all vibrations in the passenger cabin. The wheels motion can be so finely controlled that the body of the car remains level regardless of whats happening at the wheel. The LE1VI 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一shifting suspension wont 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.中文译文汽车悬架如何工作By William HarrisUniversity of Michigan当人们考虑汽车性能的时候，他们通常认为是马力，扭知和零到60的加速时。但是，如果司机无法控制汽车，由一个活塞发动机产生的功率都是无用的。这就是为什么汽车的工程师开始将注意力转向悬挂系统，尽快为他们几乎已经掌握了四冲程内燃机。 双横臂独立悬架的本田雅阁轿跑车2005年 汽车悬架的工作是尽量在轮胎和路而之间提供良好的操纵稳定性，并确保乘客的舒适度。在这篇文章中，我们将探讨汽车悬架如何的工作，他们已经逐渐发展起来，这些年来，那里的悬架设计在未来的发展方向。1、车辆动力学如果道路是完全平坦，没有违规行为，就没有必要停牌。但远离道路平坦，即使是刚铺好的公路有细微的缺陷，与汽车的车轮相联系的。它的这些缺陷聚焦于车轮。根据牛顿运动定律，所有部件都大小和方向。一个在路上碰到导致车轮向上和向下移动到垂直路面。当然大小，取决于是否是惊人的一个巨大的车轮碰撞或一点点。无论哪种方式，车轮垂直加速度的经验，因为它传递了一个缺陷。如果没有中间结构，所有车轮的垂直能量转移到车架，这在同一方向移动。在这种情况下，车轮与路面可以完全失去联系。接着，在向下的重力，车轮可以大满贯回路面。你需要的是一个系统，将吸收的能量垂直加速轮，使画面和身体不受干扰，而车轮按照道路颠簸。 对在工作力量上开动的汽车上被称为车辆动力学研究，你需要了解其中一些概念，以明白为什么暂停把必要摆在首位。大多数汽车工程师从两个角度考虑的一个移动的汽车的动态: 1）乘坐一汽车的能力，理顺了不平坦的道路 2）处理一汽车的能力，安全地加速，刹车和角落这两个特点可以进一步说明在三个重要的原则一道路隔离，进路控股和转弯。下表描述了这些原则和工程师如何尝试解决每一个独特的挑战。汽车的悬挂其各个组成部分，提供了解决方案，所有描述。2、底盘系统 一辆汽车的悬挂，其实就是在底盘，其中包括对汽车底下找到了所有重要系统的一部分。图2-1底盘 这些制度包括: 1）框架一结构，承载组件，支持汽车的引擎和身体，这反过来又受到暂停支持。 2）悬挂系统一安装支持重量，吸收冲击和削弱，并帮助维持轮胎接触。 3）转向系统一底盘，使驾驶者和直接指导的车辆。4）轮胎和轮子一部件的抓地力，使汽车运动的可能和途径或与路而摩擦力。因此，暂停只是在任何车辆的主要系统之一。 考虑到这一大画面的概述，它的时间来看看三个基本组成部分的任何中止，弹簧，减震器和防摇杆。3、弹簧1）线圈弹簧一这是弹簧的最常见的类型，而且在本质上是重型扭杆围绕一个轴圈。线圈弹簧压缩和扩展，吸收了车轮的方案。 2）钢板弹簧一这个弹簧型的多层次金属称为“叶”联系在一起，作为一个独立的单元包括。钢板弹簧被首次应用于马车，以及对最符合美国的汽车，直到1985年。他们今大仍在使用的最卡车和重型车辆。 3）扭杆一扭杆使用一种扭钢筋的性能提供线圈弹簧般的表现。这是他们的工作：一个是最后一个栏固定在车架。另一端是连接到一个叉骨，它就像一个杠杆，移动垂直扭杆行为。当点击一个车轮撞，垂直运动，是转移到叉骨，然后通过撬起行动，扭杆。扭杆然后沿其轴线曲折提供弹簧力。欧洲汽车制造商广泛使用这个系统一样，在美国惠普和克莱斯勒在20世纪50年代和60年代通过。 4）空气弹簧一空气弹簧，其中一间的轮子和汽车的空气圆柱腔体的位置组成，利用空气的压缩品质吸收车轮的震动。这个概念其实有一个多世纪的历史，可以对马拉儿童车找到。从这个时代却是从空气弹簧充气，皮革隔膜，就像一个波纹管，他们是在20世纪30年代模压橡胶空气弹簧取代。 基于在弹簧位于上车一即车轮之间的框架一工程师常常感到方便谈谈簧载质量和簧下质量。4、弹簧和簧下质量 跳跃质量是对弹簧支撑的汽车质量，而簧下质量是松散的之间的道跻和悬架弹簧质量定义。弹簧刚度的影响如何回应，而簧载质量正在驾驶汽车。松散的弹簧汽车，如豪华轿车(认为林肯城市车)，可以吞下振动，并提供一个超级平稳，但是，这样的车很容易潜水和制动和加速并趋于身体晃动转弯。紧紧弹簧车，如跑车(认为马自达Miata身上)，在颠簸的道路，但他们尽量减少身体的方案很好，这意味着他们可以更积极推动各地角落。因此，虽然自己看起来简单的弹簧装置，设计和实施他们的汽车乘客舒适度的平衡与处理是一项复杂的任务。而为了让事情更加复杂，弹簧不能单独提供一个完美的平稳运行。由于弹簧在吸收能量是巨大的，但它不是在散热良好。其他构筑物，如阻尼器众所周知，必须这样做。5、减震器除了控制