外文翻譯--汽車懸架工作原理.doc

文獻綜述附錄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. 英文翻譯附錄4英文翻譯汽車懸架工作原理William Harris密歇根大學當人們想到汽車性能時，他們通常想起的是馬力，扭矩，0到60加速時間。但是，如果司機無法控制汽車，所有的由活塞式發(fā)動機產生的功率是無用的。這就是為什么汽車的工程師就在他們幾乎已經掌握了四沖程內燃機時把他們的注意力轉向了懸掛系統(tǒng)。圖1 Honda Accord 2005 Coupe雙橫臂汽車懸架汽車懸架的工作是最大化的充分利用輪胎和路面之間的摩擦，以提供良好的操縱穩(wěn)定性，以確保乘客的舒適性。在這篇文章中，我們將探討汽車懸架是如何工作的，它們這些年經過的發(fā)展以及未來懸架設計的發(fā)展方向。汽車動力學如果道路是完全平坦的，沒有異常的情況，懸架系統(tǒng)就不是必要的。但道路往往都不是平坦的，即使是剛鋪好的公路有細微的缺陷，也能夠與汽車的車輪相互作用。它的這些缺陷聚集于車輪。根據牛頓運動定律，所有的力都有大小和方向。道路上的撞擊導致的車輪垂直上下相對于路面移動。當然大小，取決于車輪是在撞擊一個巨大的凸起還是一個微小的斑點。無論哪種方式，汽車輪轂出現的垂直加速度，是由于它通過一個路面的缺陷。若沒有中間的結構，所有車輪的垂直能量都被轉移到在同方向上移動車架上。在這樣的情況下，車輪可以完全與路面失去接觸。然后，在向下的重力下，車輪可以返回路面。你需要的是一個能夠吸收車輪垂直加速能量的系統(tǒng)，使車架和車身在車輪沿顛簸的道路行駛時不受干擾。對開動的汽車的工作動力的研究稱為汽車動力學研究，你需要了解其中的一些概念，以明白為什么懸架系統(tǒng)的重要性是首位的。大多數汽車工程師從兩個角度考慮一個行駛中的汽車的動態(tài)特征：行駛 一輛汽車行駛出坎坷道路的能力操縱 一輛汽車安全地加速，剎車和過角落的能力圖2 懸掛運動參數示意圖 這兩個特點可以進一步說明在三個重要原則道路隔離，道路附著和轉彎。下表描述了這些原則和工程師試圖解決的各不相同的挑戰(zhàn)(表略)。汽車的懸掛系統(tǒng)通過它的各個組成部分，提供所有的解決方案。讓我們看一個典型的懸架系統(tǒng)。底盤系統(tǒng)一輛汽車的懸掛，其實就是在底盤，其中包括所有該車的車身下方的的重要系統(tǒng)。這個系統(tǒng)包括車架結構、承載組件，支持汽車的引擎和車身，它們反過來又受懸架的支持懸掛系統(tǒng)承載負荷，吸收和削弱沖擊力，并幫助維持輪胎與地面的接觸轉向系統(tǒng)使司機指引車輛的機械系統(tǒng)輪胎和輪轂通過與路面的抓地力和/或摩擦力使車輛的運動方式可行的組件因此，懸架系統(tǒng)是任何車輛的一個主要系統(tǒng)。考慮到這個大圖的概述，讓我們看看汽車懸架系統(tǒng)的三個主要組成部分：彈簧、減震器和防搖桿。彈簧如今的彈簧系統(tǒng)基于四個不同的基本設計理念：線圈彈簧這是彈簧的最常見的類型，實質上是重型扭桿圍繞一個軸圈。線圈彈簧的壓縮與伸長吸收了車輪的運動能量。鋼板彈簧這個彈簧型的多層金屬稱為“簧片”聯(lián)系在一起作為一個獨立的單元。鋼板彈簧首先應用于馬車且在1985年的美國汽車上已經普及了。它們至今仍應用于大部分卡車和重型車輛。扭力桿扭力桿使用一種扭鋼筋的性能提供線圈彈簧般的表現。它們的工作原理是：桿的一端被固定到車身框架。另一端連接到一個橫臂，它就像一個杠桿，移動垂直扭力桿。當車輪有一個碰撞時，垂直的運動傳到橫臂，然后通過翹起扭力桿，之后扭力桿通過其軸線曲折提供彈簧力。歐洲的汽車制造商廣泛地使用該系統(tǒng)，就像上世紀50、60年代的美國惠普與克萊斯勒公司一樣。空氣彈簧空氣彈簧，它是在車輪和車體之間的由圓柱形空氣腔組成的，它使用壓縮空氣的質量來吸收車輪的震動。這一概念其實可以在一個多世紀前的馬拉車上發(fā)現。它從這個時代是從充氣、皮革隔膜而來，就像是一個風箱。它們是從20世紀30年代被橡膠澆筑空氣彈簧所取代的?；趶椈墒前惭b在車上即車輪和車架之間工程師們經常將它們簡單分為簧載質量與簧下質量。彈簧：簧載質量和簧下質量簧載質量是彈簧支撐的汽車質量，而簧下質量粗略的定義為道路和懸架彈簧之間的質量。當汽車被驅動時，彈簧的剛度對懸掛質量的響應有影響。松散彈簧的汽車，例如豪華轎車(認為林肯城市汽車)，可以平穩(wěn)的渡過顛簸路面并且提供一個超級平順的車程。但是，這樣的車很容易熄火，突然制動以及加速時車身容易側偏和轉彎。緊的彈簧汽車，如跑車(認為馬自達的Miata)，在顛簸的道路上，它們可以減弱車身的震動，這意味著它們可以更活躍更靈動即便是在死角轉彎時。因此，雖然看起來本身很簡單的彈簧裝置，設計并將其置于車上來保持乘客的舒適度在一個可控制的范圍內卻是一項復雜的任務。使事情更加復雜的是，僅憑彈簧是不足以提供一個完美的平穩(wěn)的行程的。為什么？那是因為彈簧雖然能夠吸收巨大的能量，但它在散熱上卻算不上良好。其他的結構，就如眾所周知的阻尼器，要求做到這一點。阻尼減震器除非抑制結構的存在，汽車彈簧將伸長并且釋放出在吸收的速度失控時碰撞產生的能量。彈簧繼續(xù)以其自然頻率反彈，直至其所有的最初的能量用盡。建立一個單獨的彈簧懸架會使行程非常的有彈性，并且不受地形控制的汽車。輸入減震器和緩沖器，一個裝置，通過控制一個不期望的彈簧運動的過程如同阻尼。用減震器減慢和減少運動振動的幅度，通