Later, engineers designed shock absorbers and springs in the suspension, which gradually became important parts of the automobile suspension structure. But so far, many people still don't understand the difference between the two. It sounds like both springs and shock absorbers should be used to reduce vibration. How can we say it separately?
Today, Rutting Jun will talk to you about the continuous love between shock absorbers and springs.
▲ The modification of shock absorbers and springs is very important in the modification of racing cars.
It looks the same, but it's actually different.
There are many kinds of springs, such as spiral springs, torsion bar springs, leaf springs, rubber springs and gas springs. Coil spring is the longest used spring in automobile suspension. Here, the most common coil spring is taken as an example to illustrate the difference between them.
There is nothing particularly magical about the spiral spring of the car, except that it is bigger than the spring we played when we were young, and the principle is basically the same. Springs are energy storage elements, which can buffer external forces. As for the cushioning effect of the spring, everyone is actually familiar with it. Many basketball shoes will adopt air cushion spring design at the bottom to achieve cushioning effect.
▲ The spring played its damping function, but it did not stabilize the car.
But buffering can't consume all the energy, because the energy will be completely released for structural reasons. In addition, without support, the spring is easy to swing up and down, and it is difficult to ensure the driving stability of the car. Because the spring is "unreliable", we need to design a device to consume this energy.
This is when the shock absorber comes in handy. Simply put, the function of the shock absorber is to form damping through the friction between the valve wall and hydraulic oil and the internal friction between hydraulic oil molecules, and convert vibration energy into heat energy, which is absorbed by the outer wall of the shock absorber and radiated to the outside air. The energy of vibration is converted into heat energy for dissipation, so that the forced vibration will not be transmitted to the car body, and passengers in the car will not feel that the car is particularly bumpy.
▲ Ford applied the spring-type shock absorber to automobiles in 1906, and successfully developed the first hydraulic shock absorber in 1908. In the following 40 years, the rocker-type hydraulic shock absorber was widely used.
Although the spring is not the main component that consumes energy, it can play a buffering role. The vibration energy of cars is often very large and the jumping speed is very fast. If there is no spring buffer, the energy consumption stroke of the shock absorber will be extended, and it is expected that the shock absorber will consume all the vibration energy in a short stroke, and the difficulty will be greatly improved. Therefore, the cooperation between spring and shock absorber becomes particularly important.
▲ Spring actually plays a big role. For example, the ratio of sprung mass to unsprung weight has a great influence on the vibration of automobiles. The larger the value, the smaller the vibration when the car passes through the bumpy road, and vice versa.
According to their characteristics, the timing of action is slightly different: in the compression stroke, the spring plays the main role, and the damping force of the shock absorber is small, so as to give full play to the elastic function of the elastic element and reduce the impact; The main function of the shock absorber is in the stretching stroke. At this time, the spring releases elastic potential energy, which increases the damping force of the shock absorber and quickly consumes energy to reduce vibration.
▲ The two need to coordinate with each other. For example, if the shock absorber is too soft, the body will jump up and down, and if the shock absorber is too hard, it will bring too much resistance and hinder the normal work of the spring.
Of course, there are cases where the combination of shock absorber and spring is not used. For example, active suspensions usually use hydraulic or pneumatic straws instead of a set of springs and shock absorbers. It is active because it can actively adjust the height and hardness of the suspension according to the road conditions, so that the car can maintain better stability and comfort under different working conditions.