Adaptive suspension - description, principle of operation and maintenance recommendations-Адаптивная подвеска – описание, принцип работы и рекомендации по обслуживанию
Unlike the standard suspension, which is usually tuned for either good handling or comfort and smoothness, the adaptive suspension performs well on all types of roads and surfaces.
PRINCIPLE OF OPERATION
The main difference between the adaptive, or as it is also called, active suspension from the classical types of suspensions is in the variable parameters of the elastic and damping elements. Ideally, three main characteristics are adapted:
dynamic characteristics of shock absorbers;
stiffness of anti-roll bars;
parameters of the mutual connection between the wheels.
However, most often, manufacturers endow only shock absorbers with the ability to change characteristics. Today, two methods are used to adjust the degree of their damping:
Changing the section of adjustable valves.
Changing the viscosity of the working fluid.
In the first case, special electromagnetic valves are built into the shock absorbers, which change the flow area of the hole for fluid to flow inside the shock absorber. Reducing the channel makes it difficult for the fluid to pass and increases the stiffness of the suspension, an increase softens it.
In the second case, there are no valves at all in the shock absorbers. This principle is based on the use of a magnetic rheological fluid that flows freely through the piston channels. Until the moment when it receives an order from the magnet, then the metal particles line up along the lines of the magnetic field and create resistance to the movement of the fluid, thus increasing the degree of damping and stiffness of the suspension.
Adjustable shock absorbers can be located both inside the air strut and outside the air spring, and also be part of such an assembly as a hydraulic spring strut. Regardless of which elastic element active suspension uses, it can change not only the rigidity of the chassis, but also other parameters: for example, ground clearance, raising the body on rough roads or reducing ground clearance at high speed to improve aerodynamic drag.
In the case of using active anti-roll bars, they are installed both on one and on both axles of the vehicle. The adaptive stabilizer differs from a conventional assembly in its design: it is not solid, but consists of two parts connected by a hydraulic twisting mechanism. When driving in a straight line, the stabilizer does not interfere with the operation of the suspension, and when cornering and rolling, its rigidity is increased by automation.
There are also other ways to adapt the suspension: adaptive rear suspension arms and a fully controlled chassis. Both of these affect mainly the parameters of the toe-in of the wheels, usually the rear ones. In the first system, a pair of additional levers is provided for this, in the second, the wheels are turned at a small angle (3-4 °) by electric motors-actuators.
CONTROL SCHEME
Naturally, all the above manipulations in the adaptive suspension take place under the strict control of the electronics - even when the driver chooses the suspension mode on his own. The control system includes:
suspension electronic control unit;
executive block;
body height sensors (common or for each individual wheel);
longitudinal, transverse and vertical acceleration sensors;
road roughness sensors (in some cases).
Based on the information received from the sensors, the control unit through the executive unit gives commands to active components: shock absorbers, stabilizers, levers, actuators, adjusting the behavior of the suspension depending on the traffic situation and according to the stiffness program selected by the driver: sports, comfort, winter, etc. .
Modes are controlled either through analog switches, or, in more modern systems, through the multimedia screen. In the latter case, as a rule, the driver is given the opportunity of both completely independent and hybrid stiffness modes, more accurately adjusting the suspension parameters for themselves.
VEHICLES WITH ADAPTIVE SUSPENSION
The pioneers of the adaptive suspension were the French from Citroen, who launched the Hydractive hydropneumatic system back in the 50s of the last century. True, due to the insufficient development of electronics, its role in this suspension was small. At the beginning of this century, with the development of electronic components, active suspension began to be widely used. One of the first to be equipped with it was General Motors cars: the comfortable Cadillac Seville sedan (since 2002) and the sports Chevrolet Corvette C5, and it was about the innovative MagneRide magnetic rheological technology. The system is still used today on GM sedans, crossovers and sports cars.
In the Old World, one of the first (after Citroen, of course) adaptive suspension was used by BMW - shock absorbers with Adaptive Drive magnetic valves in 2009 were equipped with a restyled BMW X5 / E70. Toyota (Adaptive Variable Suspension, AVS) has its own systems, successfully using it in Toyota Land Cruiser Prado, Lexus GX and other models, Opel (Continuous Damping Control, CDS) - Movano and other models. Mercedes-Benz has adaptive suspension
There are several - pneumatic Airmatic Dual Control and hydraulic spring Active Body Control. Volkswagen AG also uses two fundamentally different schemes: Adaptive Chassis Control with DCC electronically controlled dampers in the flagship Passat and Skoda Superb models, and Magnetic Ride in the Audi R8.
Korean cars Kia and Hyundai also have their own versions of the adaptive suspension, and the latter even use adaptive rear levers.
MAIN FAULTS OF ADAPTIVE SUSPENSIONS
If the main advantages of active suspension can rightfully be considered comfort, excellent handling in all situations, and, as a result, safety, then the only drawback is its cost. As when buying a car, the presence of active systems significantly affects both the price and maintenance.
Adaptive suspension sensors fail more often than other parts. This is due to their hard work, as well as the presence of mechanical reading contacts. It is easy to consider sensor malfunctions with a diagnostic scanner, however, it is difficult not to notice a malfunction without them: discomfort and reduced controllability will be felt on the go.
Adaptive dampers can leak and break electrical valves, causing them to need to be repaired or replaced. Contrary to popular belief, the reliability of modern parts is not much worse than that of ordinary shock absorbers - even taking into account domestic roads.
The pneumatics of adaptive systems can also cause trouble: compressors fail, air springs lose their tightness, and corrosion of lines occurs.
ADAPTIVE SUSPENSION SERVICE
In order for the active suspension to serve for a long time, like any other components of the car, it must be regularly serviced. To do this, it is necessary to choose qualified service stations that have not only the necessary equipment, but also experience in repairing just such complex systems. Semi-professional garage services are unlikely to help with the repair of modern electronics.
Both the price of adaptive suspension components and their impact on safety are too high to save on. In order to avoid disappointment that you do not overpay twice later, we advise you