1、文献综述 附录 3 英文原文 How Car Suspensions Work By William Harris University of Michigan 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 cant control the car. Thats
2、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 Coupe The job of a car suspension is to maximize the friction
3、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 Dy
4、namics 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
5、 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
6、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 wh
7、eels 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,
8、and you need to understand some of these concepts in order to appreciate why a 英文原文 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
9、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
10、 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-c
11、arrying 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 vehicl
12、e 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.
