Working principle of shock absorber
Time: 2022/1/3 15:58:18 | Hits: 277 |
In the suspension system, the elastic element is shocked to produce vibration. In order to improve the ride comfort of the car, a shock absorber is installed in parallel with the elastic element in the suspension to dampen vibration. The shock absorber used in the automobile suspension system is mostly hydraulic vibration reduction The working principle of the shock absorber is that when the frame (or body) and the axle are subject to vibration, the piston in the shock absorber moves up and down, and the oil in the shock absorber cavity repeatedly passes through different chambers. The pore flows into another cavity. At this time, the friction between the hole wall and the oil and the internal friction between the oil molecules form a damping force on the vibration, so that the vehicle vibration energy is converted into oil heat energy, which is then absorbed by the shock absorber and emitted into the atmosphere. When the oil channel cross section and other factors 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 oil viscosity.
The shock absorber and the elastic element undertake the task of buffering shock and damping vibration. Excessive damping force will deteriorate the suspension elasticity and even damage the shock absorber connector. Because of the contradiction between adjusting 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 as to give full play to the elastic effect of the elastic element and alleviate the impact. At this time, the elastic element plays a major role.
(2) During 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 vibration should be quickly reduced.
(3) When the relative speed between the axle (or wheel) and the axle is too high, the shock absorber is required to automatically increase the fluid flow, so that the damping force is always kept within a certain limit to avoid excessive impact Load.
In the automobile suspension system, the cylindrical shock absorber is widely used, and it can dampen the vibration in both compression and extension strokes. It is called a two-way-acting shock absorber. There is also a new type of shock absorber, which includes a gas-filled shock absorber. Vibrator and resistance adjustable shock absorber.
Explanation of the working principle of the double-acting cylindrical shock absorber. During the compression stroke, it means that the wheels of the car move closer to the body and the shock absorber is compressed. At this time, the piston 3 in the shock absorber moves downward. The volume of the lower chamber of the piston decreases, the oil pressure rises, and the oil flows through the flow valve 8 to the chamber (upper chamber) above the piston. Part of the space in the upper cavity is occupied by the piston rod 1, so the increased volume of the upper cavity is smaller than the decreased volume of the lower cavity, so a part of the oil pushes open the compression valve 6 and flows back to the oil storage cylinder 5. The oil saving of these valves forms the damping force of the suspension under compression movement. During the extension stroke of the shock absorber, the wheel is equivalent to being far away from the body, and the shock absorber is stretched. At this time, the piston of the shock absorber moves upward. The oil pressure in the upper cavity of the piston rises, the flow valve 8 is closed, and the oil in the upper cavity pushes open the expansion valve 4 and flows into the lower cavity. Due to the existence of the piston rod, the oil flowing from the upper cavity is not enough to fill the increased volume of the lower cavity, and the lower cavity is mainly caused to generate a vacuum degree. At this time, the oil in the oil storage cylinder pushes open the compensation valve 7 and flows into the lower cavity. Replenish. Because of the throttling effect of these valves, the suspension has a damping effect during extension movement.
Because the spring stiffness and pre-tightening force of the extension valve are designed to be greater than that of the compression valve, under the same pressure, the sum of the channel load area of the extension valve and the corresponding normally-open gap is smaller than the sum of the cross-sectional area of the compression valve and the corresponding normally-open gap channel. This makes the damping force generated by the extension stroke of the shock absorber greater than the damping force of the compression stroke, which meets the requirements of rapid vibration reduction.
In order to accelerate the attenuation of the vibration of the frame and the body, and to improve the driving smoothness (comfort) of the car, shock absorbers are installed in the suspension system of most cars.
