【導(dǎo)讀】廣泛應(yīng)用在轎車前輪上。等長雙橫臂式懸架在車輪上下跳動時，能保持主銷傾角不變，但輪距變化大(與單。橫臂式相類似)，造成輪胎磨損嚴重，現(xiàn)已很少用。接受的限定范圍內(nèi)，這種結(jié)構(gòu)有利于減少輪胎磨損，提高汽車行駛平順性和方向穩(wěn)定性，保證汽車具有良好的行駛穩(wěn)定性。目前不等長雙橫臂式懸架已廣泛應(yīng)用在轎車的前后懸架。上，部分運動型轎車及賽車的后輪也采用這一懸架結(jié)構(gòu)。

　　

【正文】 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 wheel39。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 pletely. 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 car39。s ability to smooth out a bumpy road ? Handling a car39。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 and how engineers attempt to solve the challenges unique to each. Principle Definition Goal Solution Road Isolation The vehicle39。s ability to absorb or isolate road shock from the passenger partment Allow the vehicle body to ride undisturbed while traveling Absorb energy from road bumps and dissipate it without causing 華東交通大學(xué)畢業(yè)設(shè)計 23 over rough roads. undue oscillation in the vehicle. Road Holding The degree to which a car maintains contact with the road surface in various types of directional changes and in a straight line (Example: The weight of a car will shift from the rear tires to the front tires during braking. Because the nose of the car dips toward the road, this type of motion is known as dive. The opposite effect squat occurs during acceleration, which shifts the weight of the car from the front tires to the back.) Keep the tires in contact with the ground, because it is the friction between the tires and the road that affects a vehicle39。s ability to steer, brake and accelerate. Minimize the transfer of vehicle weight from side to side and front to back, as this transfer of weight reduces the tire39。s grip on the road. Cornering The ability of a vehicle to travel a curved path Minimize body roll, which occurs as centrifugal force pushes outward on a car39。s center of gravity while cornering, raising one side of the vehicle and lowering the opposite side. Transfer the weight of the car during cornering from the high side of the vehicle to the low side. A car39。s suspension, with its various ponents, provides all of the solutions described. 何建勛： 雙橫臂獨立懸架設(shè)計 24 Let39。s look at the parts of a typical suspension, working from the bigger picture of the chassis down to the individual ponents that make up the suspension proper. The Chassis The suspension of a car is actually part of the chassis, which prises all of the important systems located beneath the car39。s body. Chassis These systems include: ? The frame structural, loadcarrying ponent that supports the car39。s 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 ponents 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 bigpicture overview in mind, it39。s time to look at the three fundamental ponents of any suspension: springs, dampers and antisway bars. Springs Today39。s springing systems are based on one of four basic designs: Coil springs This is the most mon type of spring and is, in essence, a heavyduty torsion bar coiled around an axis. Coil springs press 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 horsedrawn carriages and were found on most American automobiles until 1985. They are still used today on most trucks and heavyduty vehicles. 華東交通大學(xué)畢業(yè)設(shè)計 25 ? Torsion bars Torsion bars use the twisting properties of a steel bar to provide coilspringlike 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. Photo courtesy HowStuffWorks Shopper Torsion bar ? Air springs Air springs, which consist of a cylindrical chamber of air positioned between the wheel and the car39。s body, use the pressive qualities of air to absorb wheel vibrations. The concept is actually more than a century old and could be found on horsedrawn buggies. Air springs from this era were made from airfilled, leather diaphragms, much like a bellows。 they were replaced with moldedrubber air springs in the 1930s. Photo courtesy HSW Shopper Air springs 何建勛： 雙橫臂獨立懸架設(shè)計 26 Based on where springs are located on a car ., betw