Working principle of shock absorber

In the suspension system, the elastic element is impacted and vibrates. In order to improve the smoothness of the car's driving, the shock absorber is installed in parallel with the elastic element in the suspension. In order to attenuate the vibration, the shock absorber used in the automobile suspension system is mostly a hydraulic shock absorber. Its working principle is that when the frame (or body) and the axle vibrate and relative movement occurs, the piston in the shock absorber moves up and down, and the oil in the shock absorber cavity repeatedly flows from one cavity through different pores to another cavity. At this time, the friction between the pore wall and the oil and the internal friction between the oil molecules form a damping force on the vibration, so that the vibration energy of the car is converted into oil heat energy, which is then absorbed by the shock absorber and dissipated into the atmosphere. When the cross-section and other factors of the oil channel remain unchanged, the damping force increases or decreases with the relative movement speed between the frame and the axle (or wheel), and is related to the viscosity of the oil.
The shock absorber and the elastic element bear the task of buffering and shock absorption. If the damping force is too large, the suspension elasticity will deteriorate and even the shock absorber connector will be damaged. Therefore, it is necessary to adjust the contradiction between the elastic element and the shock absorber.
(1) In the compression stroke (the axle and the frame are close to each other), the damping force of the shock absorber is small, so that the elastic effect of the elastic element can be fully utilized to mitigate the impact. At this time, the elastic element plays a major role.
(2) In the extension stroke of the suspension (the axle and the frame are far away from each other), the damping force of the shock absorber should be large and the shock absorption should be rapid.
(3) When the relative speed between the axle (or wheel) and the axle is too large, the shock absorber is required to automatically increase the fluid flow rate so that the damping force is always kept within a certain limit to avoid excessive impact load.
The cylinder shock absorber is widely used in the automobile suspension system, and it can play a shock absorption role in both compression and extension strokes. It is called a double-acting shock absorber. There are also new shock absorbers, which include pneumatic shock absorbers and resistance adjustable shock absorbers.