外文翻译--汽车悬架工作原理.doc

文献综述附录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 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. 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, well explore how car suspensions work, how theyve evolved over the years and where the design of suspensions is headed in the future. 英文原文Vehicle Dynamics If a road were perfectly flat, with no irregularities, suspensions wouldnt be necessary. But roads are far from flat. 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 car wheel experiences 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, 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: Ride - a cars ability to smooth out a bumpy road 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. Lets look at the parts of a typical suspension.The Chassis The suspension of a car is actually part of the chassis, which comprises all of the important systems located beneath the cars body. These systems include: The frame - structural, load-carrying component that supports the cars engine and body, which are in turn supported by the suspension The suspension system - setup that supports weight, absorbs and dampens shock and helps maintain tire contact The steering system - mechanism that enables the driver to guide and direct the vehicle 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. Springs Todays springing systems are based on one of four basic designs: 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. 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 cars 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 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 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. 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, its best to look inside a shock absorber to see its structure and function. 英文翻译附录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。但是，如果司机无法控制汽车，所有的由活塞式发动机产生的功率是无用的。这就是为什么汽车的工程师就在他们几乎已经掌握了四冲程内燃机时把他们的注意力转向了悬挂系统。图1 Honda Accord 2005 Coupe双横臂汽车悬架汽车悬架的工作是最大化的充分利用轮胎和路面之间的摩擦，以提供良好的操纵稳定性，以确保乘客的舒适性。在这篇文章中，我们将探讨汽车悬架是如何工作的，它们这些年经过的发展以及未来悬架设计的发展方向。汽车动力学如果道路是完全平坦的，没有异常的情况，悬架系统就不是必要的。但道路往往都不是平坦的，即使是刚铺好的公路有细微的缺陷，也能够与汽车的车轮相互作用。它的这些缺陷聚集于车轮。根据牛顿运动定律，所有的力都有大小和方向。道路上的撞击导致的车轮垂直上下相对于路面移动。当然大小，取决于车轮是在撞击一个巨大的凸起还是一个微小的斑点。无论哪种方式，汽车轮毂出现的垂直加速度，是由于它通过一个路面的缺陷。若没有中间的结构，所有车轮的垂直能量都被转移到在同方向上移动车架上。在这样的情况下，车轮可以完全与路面失去接触。然后，在向下的重力下，车轮可以返回路面。你需要的是一个能够吸收车轮垂直加速能量的系统，使车架和车身在车轮沿颠簸的道路行驶时不受干扰。对开动的汽车的工作动力的研究称为汽车动力学研究，你需要了解其中的一些概念，以明白为什么悬架系统的重要性是首位的。大多数汽车工程师从两个角度考虑一个行驶中的汽车的动态特征：行驶 一辆汽车行驶出坎坷道路的能力操纵 一辆汽车安全地加速，刹车和过角落的能力图2 悬挂运动参数示意图 这两个特点可以进一步说明在三个重要原则道路隔离，道路附着和转弯。下表描述了这些原则和工程师试图解决的各不相同的挑战(表略)。汽车的悬挂系统通过它的各个组成部分，提供所有的解决方案。让我们看一个典型的悬架系统。底盘系统一辆汽车的悬挂，其实就是在底盘，其中包括所有该车的车身下方的的重要系统。这个系统包括车架结构、承载组件，支持汽车的引擎和车身，它们反过来又受悬架的支持悬挂系统承载负荷，吸收和削弱冲击力，并帮助维持轮胎与地面的接触转向系统使司机指引车辆的机械系统轮胎和轮毂通过与路面的抓地力和/或摩擦力使车辆的运动方式可行的组件因此，悬架系统是任何车辆的一个主要系统。考虑到这个大图的概述，让我们看看汽车悬架系统的三个主要组成部分：弹簧、减震器和防摇杆。弹簧如今的弹簧系统基于四个不同的基本设计理念：线圈弹簧这是弹簧的最常见的类型，实质上是重型扭杆围绕一个轴圈。线圈弹簧的压缩与伸长吸收了车轮的运动能量。钢板弹簧这个弹簧型的多层金属称为“簧片”联系在一起作为一个独立的单元。钢板弹簧首先应用于马车且在1985年的美国汽车上已经普及了。它们至今仍应用于大部分卡车和重型车辆。扭力杆扭力杆使用一种扭钢筋的性能提供线圈弹簧般的表现。它们的工作原理是：杆的一端被固定到车身框架。另一端连接到一个横臂，它就像一个杠杆，移动垂直扭力杆。当车轮有一个碰撞时，垂直的运动传到横臂，然后通过翘起扭力杆，之后扭力杆通过其轴线曲折提供弹簧力。欧洲的汽车制造商广泛地使用该系统，就像上世纪50、60年代的美国惠普与克莱斯勒公司一样。空气弹簧空气弹簧，它是在车轮和车体之间的由圆柱形空气腔组成的，它使用压缩空气的质量来吸收车轮的震动。这一概念其实可以在一个多世纪前的马拉车上发现。它从这个时代是从充气、皮革隔膜而来，就像是一个风箱。它们是从20世纪30年代被橡胶浇筑空气弹簧所取代的。基于弹簧是安装在车上即车轮和车架之间工程师们经常将它们简单分为簧载质量与簧下质量。弹簧：簧载质量和簧下质量簧载质量是弹簧支撑的汽车质量，而簧下质量粗略的定义为道路和悬架弹簧之间的质量。当汽车被驱动时，弹簧的刚度对悬挂质量的响应有影响。松散弹簧的汽车，例如豪华轿车(认为林肯城市汽车)，可以平稳的渡过颠簸路面并且提供一个超级平顺的车程。但是，这样的车很容易熄火，突然制动以及加速时车身容易侧偏和转弯。紧的弹簧汽车，如跑车(认为马自达的Miata)，在颠簸的道路上，它们可以减弱车身的震动，这意味着它们可以更活跃更灵动即便是在死角转弯时。因此，虽然看起来本身很简单的弹簧装置，设计并将其置于车上来保持乘客的舒适度在一个可控制的范围内却是一项复杂的任务。使事情更加复杂的是，仅凭弹簧是不足以提供一个完美的平稳的行程的。为什么？那是因为弹簧虽然能够吸收巨大的能量，但它在散热上却算不上良好。其他的结构，就如众所周知的阻尼器，要求做到这一点。阻尼减震器除非抑制结构的存在，汽车弹簧将伸长并且释放出在吸收的速度失控时碰撞产生的能量。弹簧继续以其自然频率反弹，直至其所有的最初的能量用尽。建立一个单独的弹簧悬架会使行程非常的有弹性，并且不受地形控制的汽车。输入减震器和缓冲器，一个装置，通过控制一个不期望的弹簧运动的过程如同阻尼。用减震器减慢和减少运动振动的幅度，通