Xiamen Monake Import And Export Co., Ltd
What does suspension parts do
Jul 28, 2020

In order to improve vehicle ride comfort, shock absorbers are installed in parallel with elastic elements in suspension system. In order to attenuate vibration, hydraulic shock absorbers are mostly used in suspension system. Their working principle is when the vibration between frame (or body) and vehicle bridge occurs relative motion. The piston in the shock absorber moves up and down, and the oil in the shock absorber chamber flows repeatedly from one chamber to another through different holes. At this time, the friction between the hole wall and the oil and the internal friction between the oil molecules form a damping force to the vibration, which transforms the vibration energy of the vehicle into the oil thermal energy, and then absorbed and emitted into the atmosphere by the shock absorber. When the cross section and other factors of the oil passage remain unchanged, the damping force increases and decreases with the relative velocity between the frame and the axle (or wheel), and is related to the oil viscosity.

Shock absorbers and elastic components undertake the task of cushioning and shock absorption. Excessive damping force will deteriorate the suspension elasticity and even damage the connecting parts of shock absorbers. Therefore, the contradiction between elastic elements and shock absorbers should be adjusted.

(1) During the compression stroke (the bridge and frame are close to each other), the shock absorber has less damping force, so as to give full play to the elastic role of the elastic elements and mitigate the impact. At this time, elastic elements play a major role.

(2) During the suspension stretching journey (the bridge and frame are far away from each other), the shock absorber should have large damping force and quickly reduce the vibration.

(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, so that the damping force is always within a certain limit, in order to avoid bearing excessive impact load.

Cylindrical shock absorbers are widely used in automotive suspension systems, and they can play a role in both compression and stretching stroke, called bi-directional shock absorbers. There are also new types of shock absorbers, which include inflatable shock absorbers and adjustable resistance shock absorbers.

The working principle of the two-way action cylinder shock absorber shows that during the compression stroke, the wheel of the car moves close to the body, the shock absorber is compressed, and the piston in the shock absorber moves downward. The volume of the lower chamber of the piston decreases, the oil pressure increases, and the oil flows through the flow valve to the upper chamber (upper chamber) of the piston. The upper chamber is occupied by the piston rod, so the increased volume of the upper chamber is less than the reduced volume of the lower chamber. A part of the oil then pushes the compression valve open and flows back to the storage cylinder. The oil savings of these valves form the damping force of the suspension in compressive motion. When the shock absorber stretches, the wheel is equivalent to far away from the body, and the shock absorber is stretched. Then the piston of the shock absorber moves upward. The oil pressure in the upper chamber of the piston rises, the flow valve closes, and the oil in the upper chamber pushes the expansion valve into the lower chamber. Because of the existence of piston rod, the oil flowing from the upper chamber is not enough to fill the increased volume of the lower chamber, which mainly causes a vacuum in the lower chamber. At this time, the oil in the storage cylinder pushes the compensation valve 7 to flow into the lower chamber to supplement. Because of the throttling effect of these valves, the suspension can be damped when it is in stretching motion.

Because the spring stiffness and pre-tightening force of the expansion valve are larger than that of the compression valve, under the same pressure, the total carrying area of the expansion valve and the corresponding constant-pass gap is smaller than that of the compression valve and the corresponding constant-pass gap channel. This makes the damping force produced by the extension stroke of the shock absorber larger than that produced by the compression stroke, and meets the requirement of rapid shock absorption.

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