Air suspension (air spring)
Car air suspension is a type of suspension, with which it is possible to adjust the clearance (body height relative to the roadway). Currently, air suspension is quite widely used on trucks and semi-trailers. Cars are also equipped with air suspension, but this applies to a greater extent to business class cars.
In the air suspension, pneumatic supports on each wheel are used as elastic elements. It is worth noting that air suspension is not a separate type of car suspension. Air suspension can be based on existing suspension designs. Pneumatic elements can be mounted on MacPherson struts, multi-link suspension, elastic beam and others.
The main purpose of the air suspension is to provide a higher level of safety and driving comfort. It is worth noting that the adaptive suspension of many business-class cars is based on pneumatic elastic elements with dynamically changing stiffness.
Varieties of Air Suspension
Three main types of air suspension can be distinguished: single, double and four-loop. It should also be noted that the air suspension can be included in the vehicle equipment, and can be installed independently. With self-installation, most often the air suspension only allows you to change the height of the body in manual mode.
● The single-loop system is installed on only one axis of the vehicle. It can be both front and rear axle. In a standard version, single-circuit systems most often include trucks and tractor units. In this case, it is possible to adjust the stiffness of the rear axle depending on the vehicle load.
● The dual-circuit air suspension system can be installed on either one axis or two. In the case of a single axle installation, the wheels are independently regulated. If a dual-loop system controls two axes, then this is similar to two single-loop systems.
The four-loop system is the most complex, but also the most functional. In such a system, the pneumatic support of each wheel is adjusted. In a four-circuit system, as a rule, an electronic control unit is used, which, in combination with sensors, automatically adjusts the pressure in the pneumatic elements.
Air suspension device /
The simplest air suspension has the following main elements in the design:
● elastic pneumatic elements on each wheel
● compressed air supply (compressor)
● air receiver
● sensors and suspension control unit
Elastic pneumatic elements are actuators of the suspension, the tasks of which include the adjustment and maintenance of clearance. Adjustment can be carried out both in manual and in automatic mode. Changing the height of the body relative to the road is carried out by changing the air pressure in the pneumatic elements.
The pneumatic element can have different designs – an independent unit or combined with a shock absorber. In the second case, an elastic pneumatic element is most often called a pneumatic shock absorber strut. Pneumatic racks can be installed on almost any type of suspension. Structurally, the pneumatic element consists of a body, a rod with a piston, and a cuff.
The compressor is designed to supply compressed air to the receiver and further to the actuators. It is worth noting that the compressor is the main structural element of the suspension, because without compressed air the operation of the air suspension is simply impossible. Air receiver Kaibintech is designed to carry out adjustments of clearance in small limits without the participation of a compressor. Also, due to the receiver, fast and adequate operation of adaptive suspensions is achieved.
Air lines connect all the elements of the air suspension into a single pneumatic system. Electronic sensors allow you to monitor such parameters as the position of the body relative to the road, the tilt of the body, the acceleration of the car and other parameters. The control unit is designed to process sensor signals and implement automatic or manual suspension adjustment.
The principle of operation of the air suspension
The air suspension allows you to adjust the height of the body in manual and automatic mode. In manual mode, the driver has the ability to independently increase or decrease the ride height. And if the suspension design has pneumatic shock absorber struts, then in this case it is also possible to adjust the suspension stiffness.
The automatic mode of operation of different suspensions may vary significantly. It is worth noting that it is precisely the adaptive suspensions that work in the automatic mode, whose duties include maintaining a certain clearance and stiffness of shock absorbers depending on various conditions. Most often, such parameters as speed, acceleration, tilt and others are used in the adaptive air suspension operation algorithm.
Depending on the speed of movement, the intensity of acceleration, the system adjusts the clearance value for the best aerodynamics of the car. When cornering at high speed, the machine rolls are evaluated, and due to compressed air, the stiffness of the loaded shock absorber racks increases. Adaptive air suspension allows you to minimize the center of gravity of the car, thereby achieving better handling and aerodynamics.
Air Suspension: Pros and Cons
Like any other system, air suspension has its advantages and disadvantages. The main advantage of the air suspension is the high smoothness of the car and the absence of any noise, since compressed air is used as an elastic element. However, depending on the purpose of the vehicle, the air suspension can be stiff.
The advantages also include automatic adjustment of clearance and stiffness of individual racks in motion. However, this applies only to factory versions of adaptive suspensions. Self-installation of a four-circuit air suspension with automatic control is very difficult and costly, so this practice is not applied.
The disadvantages include very poor maintainability of the air suspension elements. So, for example, pneumatic racks are absolutely unrepeatable and should only be replaced when they fail. It is also worth noting that the temperature of the air suspension is negatively affected by negative temperatures and road reagents.