Shock absorber terminology
Absorber is mainly used to suppress the shock and impact from the road when the spring bounces back after absorbing the shock.
When passing over uneven road, although the shock absorbing spring can filter the vibration from the road, the spring itself will have reciprocal movement, and the shock absorber is used to suppress this spring jump.
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 prevent the springs from working properly.
In the process of suspension modification, a hard shock absorber should be matched with a hard spring, and the hardness of the spring is closely related to the weight of the car, so a heavier car usually uses a harder shock absorber.
The device connected to the crankshaft of the pilot shock is used to counteract the torsional vibration of the crankshaft (i.e., the phenomenon of the crankshaft being torqued by the impact of the cylinder ignition).
1. Explanation of shock absorber terminology
Absorber (Absorber), shock absorber is mainly used to suppress the shock and impact from the road when the spring absorbs the shock and rebound.
2 The working principle of shock absorber
In order to improve the smoothness of the car, the shock absorber is installed in parallel with the elastic element in the suspension, and in order to attenuate the vibration, the shock absorber in the car suspension system is mostly a hydraulic shock absorber, whose working principle is that when the relative movement occurs between the frame (or body) and the axle due to vibration, the piston in the shock absorber moves up and down, and the oil in the shock absorber cavity will repeatedly flow from one cavity to the other.
The oil in the shock absorber cavity will repeatedly flow from one cavity to another through different orifices.
At this time, the friction between the pore wall and the oil and the internal friction between the oil molecules form a damping force to the vibration, so that the energy of the vibration of the car is converted into the heat energy of the oil, and then absorbed by the shock absorber and distributed to 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 axle (or wheel) and is related to the oil viscosity.
Shock absorber and elastic element undertake the task of slow impact and damping, the damping force is too large, will make the suspension elastic bad, and even damage the shock absorber connection damage.
Because of the surface to adjust the elastic element and shock absorber this contradiction.
In order to improve the smoothness of the car, the shock absorber is installed in parallel with the elastic element in the suspension, and in order to attenuate the vibration, the shock absorber in the car suspension system is mostly a hydraulic shock absorber, whose working principle is that when the relative movement occurs between the frame (or body) and the axle due to vibration, the piston in the shock absorber moves up and down, and the oil in the shock absorber cavity will repeatedly flow from one cavity to the other.
The oil in the shock absorber cavity will repeatedly flow from one cavity to another through different orifices.
At this time, the friction between the pore wall and the oil and the internal friction between the oil molecules form a damping force to the vibration, so that the energy of the vibration of the car is converted into the heat energy of the oil, and then absorbed by the shock absorber and distributed to 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 axle (or wheel) and is related to the oil viscosity.
Shock absorber and elastic element undertake the task of slow impact and damping, the damping force is too large, will make the suspension elastic bad, and even damage the shock absorber connection damage.
Because of the surface to adjust the elastic element and shock absorber this contradiction.
As the spring stiffness and preload of the extension valve are designed to be larger than that of the compression valve, under the same pressure, the sum of the channel loading area of the extension valve and the corresponding normal slit is smaller than the sum of the channel cross-sectional area of the compression valve and the corresponding normal slit.
This makes the damping force generated by the extension stroke of the damper greater than the damping force of the compression stroke, which achieves the requirement of rapid damping.
3 Classification of shock absorbers
1. Material angle division
From the perspective of the damping material generated, there are two main types of shock absorbers, hydraulic and inflatable, and a variable damping shock absorber.
(1) Hydraulic type
Hydraulic shock absorbers are widely used in automobile suspension systems.
The principle is that when the frame and the axle do reciprocating relative movement of the piston in the cylinder barrel of the shock absorber reciprocating movement, the fluid in the shock absorber shell will repeatedly flow from the inner cavity into another inner cavity through some narrow orifices.
At this time, the friction between the liquid and the inner wall and the internal friction of the liquid molecules will form the damping force on the vibration.
(2) Inflatable type
The inflatable shock absorber is a new type of shock absorber developed in the 60s.
Its structure is characterized by a floating piston in the lower part of the cylinder barrel, and a closed gas chamber formed at one end of the floating piston, and the cylinder barrel is filled with high-pressure nitrogen.
The floating piston is equipped with a large section of O-ring, which completely separates the oil and gas.
The working piston is equipped with a compression valve and extension valve that changes the cross-sectional area of the passage with the speed of its movement.
When the wheel jumps up and down, the working piston of the shock absorber does reciprocating movement in the oil, so that the oil pressure difference is generated between the upper and lower chambers of the working piston, and the pressure oil pushes open the compression valve and the extension valve and flows back and forth.
As the valve produces a large damping force on the pressure oil, the vibration is attenuated.
2. Structure angle division
The structure of the shock absorber is a piston rod with a piston inserted into a barrel, which is filled with oil.
The piston has a throttle hole so that the oil in the two parts separated by the piston can replenish each other.
Damping is generated when oil with viscosity passes through the throttle hole.
The smaller the throttle hole, the greater the damping force, and the greater the viscosity of the oil, the greater the damping force.
If the size of the throttle hole remains the same, when the shock absorber works fast, too much damping will affect the shock absorption.
Therefore, a disc-shaped plate spring valve is set at the outlet of the throttle hole, and when the pressure becomes large, the valve is jacked open, the throttle hole opening becomes larger and the damping becomes smaller.
Since the piston is moving in both directions, there are plate spring valves on both sides of the piston, which are called compression valves and extension valves respectively.
The shock absorber according to its structure, is then divided into two kinds of single cylinder and double cylinder. It can be further divided into single-cylinder air pressure shock absorber, a double-cylinder oil pressure shock absorber, and a double-cylinder oil gas shock absorber.
(1) Double cylinder type
The shock absorber has two cylinders inside and outside, and the piston moves in the inner cylinder.
As the piston rod enters and withdraws, the volume of the oil in the inner cylinder increases and contracts, so the balance of the oil in the inner cylinder is maintained by exchanging with the outer cylinder.
So there should be four valves in the double barrel shock absorber, that is, in addition to the two throttle valves on the piston mentioned above, there are flow valves and compensation valves installed between the inner and outer barrels to complete the exchange function.
(2) Single cylinder type
Compared with the double-cylinder type, the single-cylinder type shock absorber has a simple structure and a reduced set of valve systems.
It is equipped with a floating piston in the lower part of the cylinder barrel, (the so-called floating means that there is no piston rod to control its movement), and a closed gas chamber is formed under the floating piston, filled with high-pressure nitrogen.
The above-mentioned changes in fluid level caused by the piston rod entering and leaving the fluid are automatically accommodated by the floating piston.
In addition to the two types of shock absorbers mentioned above, there is also a resistance-adjustable shock absorber.
It can be operated externally to change the size of the throttle hole.
Recent cars have electronically controlled shock absorbers as standard equipment, which detect the driving condition by sensors and calculate the optimal damping force by computer so that the damping force adjustment mechanism on the shock absorber works automatically.
4. Basic introduction of cartridge shock absorber
The shock absorber is widely used in automobile suspension systems, and it can play the role of shock absorption in both compression and extension stroke, so it is also called two-way action shock absorber.
The components include a piston rod, working cylinder, piston, extension valve, reservoir cylinder, compression valve, compensation valve, flow valve, guide seat, dust cover, and oil seal.
When the car wheels move closer to the body and the shock absorber is compressed, the piston in the shock absorber moves downward at this time.
The volume of the lower chamber of the piston decreases, the oil pressure rises, and the oil flows to the chamber above the piston (upper chamber) through the flow valve.
The upper chamber is partly occupied by the piston rod, thus the volume increased by the upper chamber is smaller than the volume reduced by the lower chamber, and part of the oil then pushes open the compression valve and flows back to the storage cylinder.
The saving of oil by these valves forms the damping force for the suspension subjected to compression movement.
The shock absorber in the wheel is away from the body, the shock absorber is stretched, and this time the shock absorber piston moves upward.
The oil pressure rises in the upper chamber of the piston, the flow valve closes and the oil in the upper chamber pushes open the extension valve to flow into the lower chamber.
Due to the existence of the piston rod, the oil flowing from the upper chamber is not enough to fill the increased volume of the lower chamber, the main cause is a vacuum in the lower chamber, then the oil in the storage cylinder pushes open the compensation valve to flow into the lower chamber for replenishment.
Due to the throttling effect of these valves, it plays a damping role in the suspension when doing extension movement.
