How Car Suspensions Work

沙手哥哥

Table of Contents:
›   Introduction to How Car Suspensions Work
›   Vehicle Dynamics
›   The Chassis
›   Springs
›   Springs: Sprung and Unsprung Mass
›   Dampers: Shock Absorbers
›   Dampers: Struts and Anti-sway Bars
›   Suspension Types: Front
›   Suspension Types: Rear
›   Specialized Suspensions: The Baja Bug
›   Specialized Suspensions: Formula One Racers
›   Specialized Suspensions: Hot Rods
›   The Future of Car Suspensions
›   Lots More Information
›   Compare Prices for Car Suspensions
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.

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 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.
Vehicle Dynamics（汽车动力学）
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 Newton's laws of motion（牛顿运动理论）, all forces have both magnitude（大小） and direction. A bump（撞击）in the road causes the wheel to move up and down perpendicular（垂直的） to the road surface. The magnitude, of course, depends on whether the wheel is striking a giant bump or a tiny speck（斑点）. Either way, the car wheel experiences a vertical acceleration as it passes over an imperfection.


Without an intervening（介入） 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:
•        Ride - a car's ability to smooth out a bumpy road
•        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 and how engineers attempt to solve the challenges unique to each.
Principle        Definition        Goal        Solution
Road Isolation        The vehicle's ability to absorb or isolate road shock from the passenger compartment        Allow the vehicle body to ride undisturbed while traveling over rough roads.        Absorb energy from road bumps and dissipate（驱散） it without causing undue（不恰当的） oscillation（振动） 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 vehicle'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 tire'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 car'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 car's suspension, with its various components, provides all of the solutions described.
Let's look at the parts of a typical suspension, working from the bigger picture of the chassis down to the individual components that make up the suspension proper.

chun3001

英语阅读能力下降真厉害，唉，必须要好好补课了