Automotive Vibration Damper Basics And Auto Parts Industry Knowledge

Shock absorber is an appliance that accelerates the attenuation of vibrations in the frame and body to improve the smoothness (comfort) of the vehicle, and is fitted inside the suspension system of most automobiles.

1. Shock Absorber Function
Shock absorbers are used to eliminate vibrations caused by road input. That is, the elastic energy of the bullet is converted into thermal energy using a fluid, so that the convergence of the vehicle motion is most rationalised in order to give the driver a sense of comfort and stability, and to help improve driving stability.
2.Shock Absorber Construction

A shock absorber consists of a piston valve and a bottom valve (Body Valve) that generate damping force, a cylinder body and storage tube that store oil and gas (air), a connecting rod that conveys the movement of the body, and an oil seal that prevents leakage of internal gas or oil.

Moreover, based on the piston valve, the upper chamber is called the upper piston chamber, the lower chamber is called the lower piston chamber, and the space between the storage tube and the cylinder body is called the storage chamber. The upper and lower piston chambers are always filled with oil, and the lower part of the storage chamber is filled with oil and the upper part with 
air or gas (nitrogen).

3. Functions of shock absorbers

1) Cushioning the large vibration conveyed to the Body while driving to improve the ride comport
-Cushioning the shock transmitted to the driver and passengers to improve ride comfort and reduce fatigue.
-Protects the loaded cargo.
-Extends the life of the Body and prevents spring damage

2) Suppresses the rapid vibration of the wheels while driving to prevent the tyres from leaving the road surface, thus improving Ride Handling.
-Improves driving stability and adjustability.
-Effectively transmits engine burst pressure to the ground to save fuel costs
-Improves braking effect.
-Extends the life of all parts of the car body and saves on car maintenance costs.

4. Types of Shock Absorbers

Shock absorbers can be categorized according to the principle of operation, whether or not there is a storage tube, and the type of storage chamber installation.

According to the principle of operation, it can be divided into: double-acting type / single-acting type.

Double-acting type: Damping forces are generated at the start of both rebound and compression  (most of the damper belongs to this type)

Single-acting type: in the vehicle unidirectional start-up damping force generated (Mainly generate damping force during extension, suitable for off-road vehicles.)

5.Damping Force Characteristics Of Shock Absorbers

6.Main Variables Of Internal Pressure Characteristics

-Internal volume of the shock absorber: total internal volume of the shock absorber at Lmax.
-Storage volume: storage volume of the shock absorber at Lmax oil 
-Volume and stroke: (Lmax ←> Lmin) volume change
-Oil level: Oil level in the reservoir at Lmax.
-Pucture temperature: The temperature at which the volume of oil expands (0.008c/°C) and the storage volume becomes zero.

-Use pressure of oil seal

As above, the low-speed interval and high-speed interval damping force generation and control factors are different, with the result that the low-speed interval and high-speed interval damping force change has a discontinuity, this discontinuity is called the blowout point.

The Body Valve, which generates the damping force at the side of the compression, is the same as the Body Valve, and the structure of the Body Valve is shown in the figure below.

Low damping force contributes to ride comfort, so this characteristic has its benefits, but at the point of discontinuity, there is a drastic change in force, so it has a detrimental effect on ride comfort. Moreover, if the damping force is not generated in the low-speed field, the slow rocking of the vehicle body cannot be suppressed, and also the transitional attitude change cannot be suppressed, so it leads to violent vibration, and it becomes a cause of affecting the ride comfort.
In order to eliminate this adverse effect, a two-stage valve with the following Lower Velocity Valve is used to generate stable damping force at low operating speeds.

Valve Characteristics

7.Comparison of Valve (RE/CL) Characteristics

8.Comparison of Valve Structures

9.Damper Valve
Piston Valve Types