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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 Suspensions
William Harris
When 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.Vehicle Dynamics
If 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 '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 road
2)Handling - a car's 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
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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 System
The 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 suspension
2) T he suspension system - setup that supports weight, absorbs and dampens shock and helps maintain tire contact
3) T he steering system - mechanism that enables the driver to guide and direct the vehicle
4) T he 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, it's time to look at the three fundamental components of any suspension: springs, dampers and anti-sway bars. 3.Springs
Today'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. 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 , 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 Mass
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The 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 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 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 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 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 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
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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 Bars
Another 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 Bars
Anti-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 Suspensions
While 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 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 LEM can extend and compress at a much greater speed, virtually eliminating all vibrations in
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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。但是，如果驾驶员无法控制汽车，则由活塞发动机产生的所有动力都是无用的。这就是为什么汽车工程师几乎一掌握四冲程内燃机就会将注意力转向悬架系统的原因。
汽车悬架的作用是使轮胎和路面之间的摩擦最大化，以提供操纵稳定性和良好的操控性并确保乘客的舒适性。在本文中，我们将探讨汽车悬架的工作原理，多年来他们如何发展以及未来悬架的设计。 1.车辆动力学
如果一条路完全平坦，没有违规行为，那么汽车的驾驶和乘坐感受就很平顺。但如果道路很不平坦。即使是新铺的高速公路也有微妙的缺陷，可以与汽车的车轮相互作用。这是对轮子施加力的这些缺陷。根据牛顿的运动定律，所有力量都具有量级和方向。路面上的颠簸导致车轮垂直于路面上下移动。当然，其大小取决于车轮是撞击巨大的碰撞还是小小的斑点。无论哪种方式，汽车车轮都经历了一个不完美的情况下垂直加速。如果没有中间结构，车轮的所有垂直能量都会转
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移到车架上，车架会沿相同的方向运动。在这种情况下，车轮可能完全失去与道路的接触。然后，在重力的向下作用下，车轮可以撞回路面。你所需要的是一个能够吸收垂直加速车轮能量的系统，当车轮跟随颠簸时，车架和车身可以不受干扰地行驶。
研究移动车上的作用力叫做车辆动力学，你需要理解其中的一些概念，以便首先了解为什么需要悬架。大多数汽车工程师从两个角度考虑动车的动态特性：
1）乘坐 - 一辆汽车平稳颠簸道路的能力 2）处理 - 汽车安全加速，制动和转弯的能力
这两个特点可以在三个重要原则中进一步描述 - 道路隔离，道路控制和转弯。下表描述了这些原则，以及工程师如何尝试解决每个独特挑战。
一辆汽车的悬挂装置及其各种组件提供了所述的所有解决方案。 2.底盘系统
汽车悬架实际上是底盘的一部分，底盘包括位于车身下方的所有重要系统。
这些系统包括：
1）车架结构，承载部件，支撑汽车的发动机和车身，并由悬架支撑
2）悬架系统 - 支撑重量的设置，吸收和减震，并有助于保持轮胎的接触
3）转向系统 - 使驾驶员能够引导和引导车辆的机制
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4）轮胎和车轮 - 通过抓地力和/或与道路摩擦的方式使车辆运动的部件
所以悬架只是任何车辆的主要系统之一。
考虑到这张大图的概述，现在是时候看看任何悬架的三个基本组成部分：弹簧，减震器和防摇摆杆。 3. 弹簧
今天的弹簧系统基于四种基本设计之一：
1）螺旋弹簧 - 这是最常见的弹簧类型，本质上是围绕轴线盘绕的重型扭力杆。螺旋弹簧压缩并膨胀以吸收车轮的运动。
2）弹簧片 - 这种类型的弹簧由几层金属（称为“叶片”）组合在一起以作为单个单元。钢板弹簧首先用于马车，并在大多数美国汽车上被发现，直到1985年。它们现在仍然用在大多数卡车和重型车辆上。
3）扭杆 - 扭杆使用钢筋的扭曲特性来提供螺旋弹簧般的性能。这是他们的工作方式：酒吧的一端固定在车架上。另一端连接到叉骨，该叉骨的作用类似于垂直于扭杆移动的杠杆。当轮子碰撞时，垂直运动转移到叉骨，然后通过杠杆作用传递到扭杆。然后扭杆沿其轴线扭转以提供弹簧力。欧洲的汽车制造商广泛使用这种系统，就像美国的Packard和克莱斯勒在20世纪50年代和60年代一样。 4）空气弹簧 - 由位于车轮和车身之间的圆柱形空气室组成的空气弹簧利用空气的压缩质量吸收车轮振动。这个概念实际上已经有一百多年的历史，可以在马车上找到。这个时代的空气弹簧是由充气的皮革隔膜制成
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的，非常像波纹管; 20世纪30年代它们被模制橡胶空气弹簧取代。
根据汽车上的弹簧位置 - 即车轮和车架之间的位置 - 工程师经常发现谈论簧上质量和簧下质量很方便。 4. 悬挂和簧下质量
悬挂质量是支撑在弹簧上的车辆的质量，而簧下质量地定义为悬挂弹簧下的机件等质量。弹簧的刚度影响汽车在行驶时簧上的质量如何响应。如豪华轿车（想想林肯城市轿车）那样松散的汽车，可以吸收颠簸并提供超级平顺的驾乘感受；然而，这样的汽车在制动和加速期间容易下潜和下蹲，并且在转弯期间倾向于身体摇摆。如跑车（认为马自达Miata），紧蹦的悬架在崎岖不平的道路上比较颠簸，但它们将车身的侧倾等摆动减到最小，这意味着它们甚至可以在很小的角落里实现灵活地转弯等。
所以，尽管弹簧本身看起来像是简单的装置，但在汽车上设计和实施它们以平衡乘客舒适性和操作性是一项复杂的任务。而要使事情更加复杂，单靠弹簧不能提供完美平稳的驾驶。为什么？因为悬架在吸收能量方面很出色，但是不善于消散能量。其他结构，称为阻尼器，需要这样做。 5.避震器
除非存在缓冲结构，否则汽车弹簧将以不受控制的速度延伸并释放其从凸起吸收的能量。弹簧将继续以自然频率反弹，直到最初投入的所有能量都用完。一个悬挂在弹簧单独建设会使一个非常有弹性的乘坐感受。
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减震器或缓冲器，即通过称为减震的过程来控制不希望的过度弹簧运动的装置。通过将悬架运动的动能转化为可通过液压流体消散的热能，减震器减速并减小振动运动的幅度。要理解这是如何工作的，最好从减震器内侧看它的结构和功能。
减震器基本上是一个放置在汽车车架和车轮之间的油泵。冲击的上部安装件连接到框架（即，簧上重量），而下部安装件连接到轮附近的轮轴（即，簧下重量）。在双管设计中，减震器是最常见的减震器之一，上部安装件连接到活塞杆上，而活塞杆又连接到活塞上，而活塞则位于装满液压油的管中。内管被称为压力管，而外管被称为储备管。储备管储存多余的液压油。
当车轮在道路上遇到碰撞并导致弹簧缠绕和展开时，弹簧的能量通过上支架传递到减震器，向下穿过活塞杆并进入活塞。当活塞在压力管中上下移动时，孔口穿透活塞并允许流体泄漏。由于孔口相对较小，在很大的压力下只有少量的流体流过。这会减慢活塞，从而减慢弹簧的速度。
减震器在两个循环中工作 - 压缩循环和延伸循环。压缩循环在活塞向下移动时发生，压缩活塞下方的腔室中的液压流体。当活塞移向压力管的顶部时，延伸循环发生，压缩活塞上方腔室中的流体。典型的汽车或轻型卡车在其延伸循环期间将具有比其压缩循环更大的阻力。考虑到这一点，压缩循环控制车辆的非簧载重量的运动，而延伸控制较重的悬挂重量。
所有现代减震器都对速度比较敏感 - 悬架移动越快，减震器提
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供的阻力越大。这可以适应冲击及道路状况，并控制行驶车辆中可能发生的所有不需要的动作，包括反弹，摇摆，刹车潜水和加速下蹲。 6.支撑杆和防倾竿
另一种常见的缓冲结构是支撑杆 - 基本上是安装在螺旋弹簧内部的减震器。 支撑杆执行两项工作：它们提供减震功能，如减震器，并为车辆悬架提供结构支撑。这意味着支柱比减震器提供更多的功能，不支持车辆重量 - 它们只控制汽车中的重量转移速度，而不是重量本身。
因为支撑杆与处理汽车侧倾等有很大关系，所以它们可以被认为是关键的安全功能。磨损的冲击和支柱可以允许从一侧到另一侧以及从前到后的过度车辆重量转移。这会降低轮胎抓地力的能力，以及操控和制动性能。 7. 防侧倾杆
防摇摆杆（也称为防侧倾杆）与减震器或支柱一起使用，使汽车具有更高的稳定性。防侧倾杆是一种跨越整个轴并有效地将悬架两侧连接在一起的金属杆。
当一个车轮的悬架上下移动时，防摆杆将运动传递到另一个车轮。这创造了更平坦的驾驶并减少了车辆摇摆。出于这个原因，今天几乎所有的汽车都配备了防侧倾杆作为标准装备，但如果他们不是，工具包可以随时安装防侧倾杆。 8.汽车悬架的未来
尽管对弹簧和减震器进行了改进，但汽车悬架的基本设计多年来
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一直未发生重大变化。但是，随着Bose设想的全新悬架设计的推出，这一切即将发生改变 - 同样以其在声学技术方面的创新而闻名的Bose也同样如此。一些专家甚至说，自推出全独立设计以来，Bose悬架是汽车悬架的最大进步。
它是如何工作的？ Bose系统在每个车轮上使用线性电磁马达（LEM）来代替传统的支撑杆和弹簧悬挂。放大器为电机提供电力，以便在每次系统压缩时都可以再生电力。这些电机的主要优势在于它们不受常规流体阻尼器固有惯性的限制。因此，线性电磁马达可以以更快的速度伸展和压缩，从而消除客舱内的所有振动。无论车轮上发生了什么，车轮的运动都可以得到很好的控制，使车身保持水平。 线性电磁马达还可以在加速，制动和转弯时抵消汽车的车身运动，给驾驶者更大的控制感。
不幸的是，这一技术在2009年之前无法使用，届时将在一个或多个高端豪华轿车上提供。在此之前，驾驶员将不得不依赖经过之前成熟的老平台悬架，这些方法已经改善了几个世纪以来的颠簸乘坐感受。
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