车辆工程外文翻译--- 悬架系统

附 录 Suspension systemsWhen 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. 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. 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. 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. A cars suspension, with its various components, provides all of the solutions described. Car Suspension PartsThe 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. SpringsTodays 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. Coil springsPhoto courtesy HowStuffWorks ShopperLeaf spring 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, through the 1950s and 1960s. Torsion bar 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. Air springsBased 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. 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 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 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 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. Anti-sway barsAnti-sway BarsAnti-sway bars are used along with shock absorbers 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 theyre not, kits make it easy to install the bars at any time. 译文 悬架系统当人们想到汽车性能，通常先到的是是马力，转矩和0到60公里的加速度。但是如果驾驶者不能操纵汽车，这些由发动机产生的功率将毫无用处。这就是为什么汽车设计师在刚掌握了四冲程内燃机时就把精力转移到了悬架系统。 2005本田双们轿车双横臂悬架 2005本田双们轿车双横臂悬架悬架的作用是最大限度的增加轮胎与地面间的摩擦力而使操纵稳定和确保乘客舒适。这里我们将探讨悬架如何工作，开展和未来的研究方向。 如果路面是纯平的，没有坎坷，悬架就不是必要的。但路面不很平坦，即使是刚铺好的公路也不是很完美，而使得车轮受到干扰，这些不平将使车轮受力，根据牛顿运动定律，力都具有大小和方向。路面上的碰撞导致车轮相对路面垂直移动，车轮碰撞剧烈还是轻微决定他的大小。如果没有这个内部结构，所有的车轮的能量都以同样的方向传到车架。这样会产生车轮与路面完全脱离，然后在向下的重力作用下车轮回到路面，因此我们需要一个能够吸收垂直加速度的系统使车架与车身在车轮与地面碰撞时无干扰的行驶。汽车悬架系统，用它的各个组成局部，提供了所有解决方法。悬架是底盘的组成局部，底盘包括了位于车身下方的所有重要系统。这些系统包括： 车 架结构,承载组件,它支持了发动机和车身,由悬架支撑。悬架系统装置，支撑重量，吸收和减少振动，帮助保持车轮接触。 转向系统机械装置，使得驾驶者指导和指挥汽车。 轮胎和车轮部件，使得汽车可以通过与路面的附着力或摩擦力进行移动。所以悬架在任何汽车上都很是重要的系统。通过上面的图片看下悬架的三大组成：弹簧，减振器，和横向稳定杆。弹簧 当今的弹簧系统基于四种根本设计： 螺旋弹簧最常见的弹簧种类，它实质上是一与一根轴螺旋盘绕的重负荷扭力棒。螺旋弹簧的压缩和伸展吸收了轮胎上下移动产生的能量。 钢板弹簧这种弹簧由假设干层金属(以下简称叶 )联系在一起,作为一个单位。他最初是用在马车上，直到1985年被用在大多数美国汽车上，直到今天大局部的卡车和重型汽车也在应用。 钢板弹簧 螺旋弹簧 扭杆簧扭杆簧是利用金属棒的扭曲特性而产生类似螺旋弹簧的性能。它的一端支撑在车架上，另一端支撑在前臂上，前臂就相当于一个杠杆相对与扭杆垂直移动。当车轮发生碰撞，垂直的移动传递到前臂，通过杠杆作用传到扭杆。然后扭杆沿着轴的方向扭曲而产生弹簧力。在19世纪50年代到60年代欧洲汽车广泛的应用这种弹簧系统， 扭杆弹簧空气弹簧空气弹簧系统,由位于车轮和车身之间的圆柱曲面空气装置组成，利用它的空气可压缩性来吸收车轮振动。这个概念事实上已有上百年的历史了，在马车时代就产生了。那个时代的空气弹簧由皮革作为隔板充气而成，很像个娄。在19世纪30年代它们被替换成塑橡胶。基于弹簧在车上的位置，例如，在车轮和车架之间-设计师为了方便会谈成簧空气弹簧上质量和簧下质量弹簧：簧上质量和簧下质量簧上质量是汽车支撑在弹簧以上的质量，簧下质量大概的定义为路面和悬架之间的质量。车辆行驶时弹簧的刚度影响簧上质量的响应。低刚度汽车，像奥拓轿车(林肯城市轿车)，可以缓解撞击，和提供一个非常好的行驶平顺性。但是这样的车容易在制动和加速时俯冲或下蹲，在转弯时摇摆或侧倾。刚刚度汽车，如如运动轿车(马自玛雅塔)，他缓解崎岖道路的冲击较差，但是他能做很小的车身运动，这意味着他能很积极的行驶，甚至过弯。所以，弹簧本身看起来是很简单的装置，可设计和实施却需要平衡乘坐舒适性和可操纵性，这是很复杂的。使得事情更复杂的是，只有弹簧不能提供完美的驾驶平顺性，为什么呢？因为弹簧在吸收能量上非常出色，可在消退能量上不是很好，另一结构，被称为减振器可以做到这点。减振器如果没有减振器，弹簧将以不可控制的速度延长和释放碰撞时吸收的能量。弹簧将以其自然频率继续跳动直到所有最初的能量被耗尽。一个只有弹簧的悬架会产生非常跳动的行驶性，并依据地形的不同，成为不可控制的汽车。减振器内部或者说是缓冲器，是一个阻尼的过程控制使弹簧不动的装置。减振器通过将悬架运动产生的动能转化为可被液压油消退的热能，使振动的频率和振幅减小。想要知道他是如何工作的，最好的方法是进入减振器内部看看他的结构和功能。减振器根本上为一个位于车架和车轮之间的油泵。他的上局部连接在车架上如簧上质量，下局部连接在半轴上，靠近车轮如簧下质量。一种最常见的减振器，双筒式液力减振器，他的上部连接在活塞杆上，活塞杆反过来接在活塞上，活塞反向位于充满液压油的筒内。筒的内部为工作腔，外层为储油腔。储油腔储存多余的液压油。当汽车在颠簸路面是行行走，导致弹簧卷曲和伸展，弹簧能量通过上部转移到减振器，向下传到活塞杆再到活塞。通过节流口油液随着活塞的上下移动镏流进工作腔。因为节流口相对很小，只有很少的油液在大的液压下通过。这就使得活塞减慢，反过来使弹簧减慢。减振器有两个工作行程，压缩形成和伸展行程。压缩行程发生在活塞想下运动时，压缩油液进入活塞下腔。伸展行程发生在活塞向作腔上部移动时压缩活塞上部的油液。典型的轿车和轻型卡车的延伸行程比压缩行程阻力大。基于这点，压缩行程控制汽车的簧下质量，而延伸行程控制较重的簧上质量。所有现代的减振器都是速度敏感，悬架动的越快减振器提供的阻力越大。这使减振器能够适应各种路况和控制行驶中的汽车会产生的任何不希望的移动，其中包括跳动,左摇右摆,制动俯冲和加速度蹲下。横向稳定杆横向稳定杆横向稳定杆与减振器一起使用，给行驶的汽车提供额外的稳定性。他是一个金属质地的杆，横跨整个车轴并且有效的连接了两边的悬架。当一边车轮的悬架上下跳动，横向稳定杆将移动转移到另一侧车轮。这就使得行驶平顺性更好和减小了车身摇晃。尤其是，他克服了车身在转弯时的侧倾。因为这点，现在几乎所有汽车都安装横向稳定杆作为标准配置，即使没有安装它也易于在任何时间安装。