It begins in the mid-50s of the last century, when the French company Citroen installed hydropneumatics on the rear axle of the representative Traction AVANT 15CV6, and a little later - on all four wheels of the DS model. On each shock absorber, the sphere was located separated by the membrane into two parts, in which the working fluid is located and the gas supporting it under pressure.
In 1989, an XM model appeared on which the active hydropneumatic Hydractiv suspension was established. Under the control of electronics, she adjusted to the road situation. Today, the Citroen employs the Hydractiv of the third generation, and along with the usual version offer and more comfortable with the Plus console.
In the last century, the hydropneumatic suspension was established not only at Citroen, but also on expensive representative cars: Mercedes-Benz, Bentley, Rolls-Royce. By the way, cars, crowned with a three-beam star, and now do not avoid such a scheme.
Active Body and other systems
The Active Body Control system (active control over the body) differs from Hydractiv, but the principle is similar: changing the pressure, they define the stiffness of the suspension and the road lumen (the hydraulic cylinders are pressed the springs). However, Mercedes-Benz has both chassis options on air suspenders (AIRMATIK DUAL CONTROL) specifying ground clearance depending on speed and loading. For the rigidity of the shock absorbers, Adaptive Damping System is an adaptive damping system). And as a more accessible version of Mercedes buyers offer Agility Control suspension with mechanical hardness instruments.
Volkswagen calls the system controlling the shock absorbers settings, DSS (Adaptive Chassis Control is adaptive suspension control). The control unit receives data from the sensors to move the wheels and body and appropriately changes the rigidity of the chassis. The characteristics set the solenoid valves installed on shock absorbers.
Audi applies similar adaptive suspension, however, on some models, the original AUDI Magnetic Ride system is installed. The damping elements are filled with a magnetorette fluid that changes the viscosity under the action of a magnetic field. By the way, the design running on the same principle was the first to apply Cadillac. And the name of the "Americans" is consonant - Magnetic Ride Control. Having inspired this family, Volkswagen is still in no hurry to part with the names of their own. The intelligent chassis from the Porsche with shock absorbers controlled by electronics, and on some models there is also a pneumatic suspension, wearing PASM designation (Porsche Active Suspension Management - active suspension control). Effectively deal with rolls and clips helps other PDCC Name Weapons (Porsche Dynamic Chassis Control - Dynamic Chassis Control). Transverse stability stabilizers with hydraulic pumps almost do not give the body from side to side. Opel Almost a decade installs IDS (Interactive Driving System - Interactive Driving System) on serial models. The main component is CDC (Continuous Damping Control - Continuous damping control), configuring shock absorbers depending on road conditions. By the way, the CDC abbreviation is used by other manufacturers, such as Nissan. In the new models Opel, cunning electronic and mechanical devices are called "flexoms". It did not exception and the suspension - it was filled with Flexride.
BMW has another cherished word - Drive. Therefore, it is quite logical that adaptive suspension is called Adaptive DRIVE. It includes Dynamic Drive Rolls Supplements and EDC Shock Absorber Stiffness Control (ELECTRONIC DAMPER CONTROL). The latter will probably soon come up with the designation with the word Drive.Toyota and Lexus enjoy general names. The stiffness of the shock absorbers is watching the AVS system (Adaptive Variable Suspension is an adaptive suspension), the road clearance adjusts the AHC pneumatic suspension (Active Height Control - active body height control). Curtains with minimal rolls allows KDSS (Kinetic Dynamic Suspension System), controlling stabilizer hydraulic drives. The analogue of the last Nissan and Infinity is the original NVMS system (Hydraulic Body Motion Control - hydraulic control over the body movement), changing the characteristics of the shock absorbers and thus reducing the cutting of the car from side to the side.
A curious idea was implemented by Hyundai, setting the AGCS rear suspension on the new Sonata (Active Geometry Control Suspension - active control over the change in geometry). Electromotors lead in motion of thrust, changing the angles of wheel installation. Thus, electronics helps to feed the feed in turns. By the way, some cars have electromotors subject to active steering, change along with the annecting angle of rotation. For example, RAS (Rear Active Steer is active rear wheels) at Infinity or Integral Active Steering at BMW.
Handbook of suspension: what is the cost?
Recently, only the types of suspension were allocated - dependent, "Mac-Fersson", multi-dimensional. The incomprehensible names appeared when the chassis learned to adapt to road situations and coating. Clear the situation.
Handbook of suspension: what is the cost?Let's first figure it out with the concepts, because now in the go different terms - an active suspension, adaptive ... So, we will assume that the active chassis is a more general definition. After all, change the characteristics of the suspensions to increase stability, controllability, getting rid of rolls, etc. You can both preventively (by pressing the button in the cabin or manual adjustment) and fully automatically.
It is in the latter case it is appropriate to talk about the adaptive chassis. Such a suspension using various sensors and electronic devices collects data on the position of the body of the car, the quality of the road surface, the motion parameters, in order to make their own work on the specific conditions, the driver piloting style or the mode selected it. The main and most important task of adaptive suspension is to determine as quickly as possible that it is under the wheels of the car and how it goes, and then instantly rebuild the characteristics: change the clearance, degree of damping, geometry suspension, and sometimes even ... adjust the angles of rotation of the rear wheels.
History of active suspension
The beginning of the history of the active suspension can be considered the 50s of the last century, when the car's hydropneumatic racks appeared on the car as elastic elements. The role of traditional shock absorbers and springs in such a design is performed by special guide hydroclides and spheres-hydroakkuumulators with a gas retail. The principle is simple: changing the pressure of the fluid - change the parameters of the chassis. In those days, such a design was very cumbersome and severe, but fully justified itself with high smoothness and the possibility of adjusting the road lumen.
Metal spheres in the diagram are an additional (for example, in the rigid pendant mode, they do not work) hydropneumatic elastic elements that are separated by elastic membranes. At the bottom of the sphere - the working fluid, and in the upper - gas nitrogen
The first hydropneumatic racks on their cars applied Citroen. This happened in 1954. The French continued to develop this topic and further (for example, on the legendary DS model), and in the 90s the debut of the more perfect hydropneumatic suspension Hydractive, which engineers continue to modernize it to this day. It was just already considered adaptive, because with the help of electronics could independently adapt to the conditions of movement: it is better to smooth out the impressions coming on the body, reduce clips when braking, fight rolls in turns, and adjust the car clearance to the vehicle speed and road Coating under the wheels. The automatic change in the rigidity of each elastic element in the adaptive hydropneumatic suspension is based on the pressure control of fluid and gas in the system (in order to object the principle of operation of such a suspension scheme, see the video below).
Shock absorbers variable stiffness
And yet over the years, the hydropneumatics did not become easier. Rather, on the contrary. Therefore, it is more logical to start the story from the most ordinary way to adapt the characteristics of the suspension under the road surface - individual control of the rigidity of each shock absorber. Recall, they need any car to clean the oscillations of the body. A typical damper is a cylinder divided into separate chambers with an elastic piston (sometimes several of them). When the suspension is triggered, the liquid flows from one cavity to another. But not free, but through special throttle valves. Accordingly, inside the shock absorber, hydraulic resistance occurs, due to which the squabble fades.
It turns out that by controlling the flow rate of the fluid, the stiffness of the shock absorber can be changed. So it means to seriously improve the characteristics of the car by fairly budget methods. After all, today regulated dampers are issued by many firms for a variety of machine models. Technology worked out.
Depending on the shock absorber device, its adjustment can be done manually (by a special screw on the damper or by pressing the button in the cabin), and also fully automatically. But since we are talking about adaptive suspensions, we will consider only the last option, which usually still allows you to adjust the suspension preventive - select a specific movement mode (for example, a standard set of three modes: Comfort, Normal and Sport).
In modern designs of adaptive shock absorbers, two main tools for regulating the degree of elasticity are used: 1. Scheme based on electromagnetic valves; 2. With the help of the so-called magnetoreological fluid.
Both varieties allow you to individually automatically change the degree of damping of each shock absorber, depending on the state of the roadway, the parameters of the car movement, piloting style and / or preventively at the request of the driver. The chassis with adaptive shock absorbers significantly changes the behavior of the car on the road, but in the regulatory range is visible, for example, hydropneumatics.
- How is an adaptive shock absorber based on electromagnetic valves?
If in the usual shock absorber, the channels in a moving piston have a constant passage section for a uniform flow of working fluid, then adaptive shock absorbers can change using special electromagnetic valves. This happens as follows: the electronics collects many different data (the reaction of the shock absorbers on compression / hang, the magnitude of the road lumen, the moves of the suspension, accelerate the body in the planes, the signal switch of the modes, etc.), and then instantly distributes individual commands to each shock absorber: dismissed or Speed \u200b\u200bat a certain time and magnitude.
At this point, inside a shock absorber, under the action of current strength, the passage of the channel changes in milliseconds, and at the same time the intensity of the flow of the working fluid. Moreover, the adjusting valve with the control solenoid can be located in different places: for example, inside the damper right on the piston, or from the side on the side of the housing.
Technologies and adjustable shock absorbers with solenoid valves are constantly being improved to achieve the maximum smooth transition from the hard state of the damper to the soft. For example, at the Bilstein shock absorbers in the piston there is a special DAMPTRonic central valve, which allows infinitely to reduce the resistance of the working fluid.
- How is an adaptive shock absorber based on magnet neuroological fluid?
If in the first case, electromagnetic valves were responsible for adjusting the stiffness, then in magnetoreological shock absorbers, it seems, as it is easy to guess, a special magnetoreological (ferromagnetic) liquid, which is filled with a shock absorber.
What kind of super competition does it have? In fact, there is nothing abundant in it: in the composition of the ferromagnetic liquid, many smallest metal particles can be detected, which react to the change in the magnetic field around the rod and the shock absorber piston. With an increase in the current of the current on the solenoid (electromagnation), the particles of the magnetic fluid build up like soldiers on the rain on the field lines, and the substance instantly changes its viscosity, creating an additional resistance to the movement of the piston inside the shock absorber, that is, making it tougher.
It used to be believed that the process of changing the degree of damping in the magnetoreological shock absorber passes faster, smasher and more accurate than in the design with an electromagnetic valve. However, at the moment both technologies have been practically equal in efficiency. Therefore, in fact, the driver of the difference almost does not feel. However, in the suspensions of modern supercars (Ferrari, Porsche, Lamborghini), where the reaction time to replace the conditions of movement plays a significant role, it is shock absorbers with a magnetoreological fluid.
Demonstration of adaptive magnetoreological shock absorbers Magnetic Ride from AUDI.
Adaptive pneumatic suspension
Of course, a pneumatic suspension occupies a special place in a number of adaptive suspensions, which to this day little can compete in smoothness. Structurally from the usual chassis, this scheme is distinguished by the absence of traditional springs, since their role is performed by elastic rubber cylinders filled with air. With the help of an electron-proof pneumatic actuator (air supply system + receiver), you can film or lower each pneumatic rack, adjusting in an automatic (or preventive) height of each part of the body within wide limits.
And in order to control the stiffness of the suspension, the most adaptive shock absorbers work for a couple with pneumatic ballons (an example of such a schema - Airmatic Dual Control from Mercedes-Benz). Depending on the design of the chassis, they can be installed both separately from the pneumatic balloon and inside it (pneumatic rack).
By the way, in the Hydropneumatic scheme (Hydractive from Citroen) in conventional needless shock absorbers, since the electromagnetic valves inside the racks, which change the intensity of the flow of the working fluid correspond to the rigidity parameters.
Adaptive hydraulic suspension
However, not necessarily the complex design of the adaptive chassis must be accompanied by a refusal of such a traditional elastic element as spring. Mercedes-Benz engineers, for example, in their Active Body Control chassis simply improved the spring rack with a shock absorber, installing a special hydraulic cylinder on it. And in the end, they received one of the most advanced adaptive suspension from the current existing ones.
Based on the data from the ski sensors, monitoring the movement of the body in all directions, as well as on indications with special stereocamers (scanning the quality of the road by 15 meters forward), the electronics can be adjusted to jewelry (discovering / closing electron hydroclap) stiffness and elasticity of each hydraulic-flowing rack. As a result, such a system almost completely eliminates the casual rolls under a wide variety of movement conditions: turn, acceleration, braking. The design reacts as quickly to the circumstances, which even made it possible to abandon the transverse stability stabilizer.
And of course, like pneumatic / hydropneumatic suspension, the hydraulic-flow scheme can adjust the position of the body in height, "play" the rigidity of the chassis, and also automatically reduce the clearance at high speed, increasing the resistance of the car.
And this video demonstration of the work of the hydraulic-flow chassis with the Magic Body Control road scan function
In short, we will remind the principle of its work: if the stereo chamber and the transverse acceleration sensor recognize the rotation, the body will automatically lean towards a small angle to the center of the varyrage (one pair of hydraulic steel racks instantly relaxes, and the other is slightly clamped). It is done to eliminate the effect of the casual roll effect, improving the comfort for the driver and passengers. However, in fact, a positive result perceives rather ... Passenger. Since the driver's roll driver is a certain signal, information thanks to which it feels and predicts one or another reaction of the machine to the maneuver. Therefore, when the "Anti-Crene" system works, the information comes with a distortion, and the driver has to psychologically rebuild, losing feedback with the car. But with this problem, engineers are fighting. For example, specialists from Porsche set up their suspension in such a way that the driver's development itself felt the driver felt, and the unwanted effects of electronics begins only when a certain degree of inclination of the body is transition.
Adaptive transverse stability stabilizer
Indeed, you correctly read the subtitle, because not only elastic elements or shock absorbers can be adapted, but also secondary elements, such as, for example, a transverse stability stabilizer used in the suspension to reduce rolls. You should not forget that with the straightforward movement of the car in rough terrain, the stabilizer has a negative impact rather, transmitting oscillations from one wheel to another and reducing the moves of the suspension ... Avoiding this allowed the adaptive transverse stability stabilizer, which can perform a standard purpose, completely disconnect and even "Play" with its rigidity depending on the magnitude of the forces acting on the body of the car.
The active stabilizer of transverse stability consists of two parts connected by a hydraulic actuator. When the special electric hydraulicide pumps the working fluid in its cavity, then parts of the stabilizer turn relative to each other, as if lifting the way the car, which is under the action of centrifugal force
Set an active transverse stability stabilizer for both one and immediately on both axes. Externally, it practically does not differ from the usual, but consists not from a solid rod or pipe, and from two parts, docked by a special hydraulic mechanism of "twisting". For example, with a straightforward movement, he dismisses the stabilizer so that the latter does not intervene in the work of the suspension. But in turns or with aggressive ride - a completely different matter. In this case, the rigidity of the stabilizer instantly increases in proportion to the increase in the lateral acceleration and forces acting on the car: the elastic element works either as usual or is also constantly adapted to the conditions. In the latter case, the electronics itself determines which way the body roll is developing, and automatically "spins" parts of stabilizers on the side of the body, which are under load. That is, under the action of this system, the car is slightly leans from turning, as well as on the aforementioned Active Body Control suspension, providing the so-called anticrene effect. In addition, active transverse stability stabilizers installed on both axes can affect the leakage of the car to demolition or drift.
In general, the use of adaptive stabilizers significantly improves the handling and stability of the car, so even on the largest and most heavy models like Range Rover Sport or Porsche Cayenne, it was possible to "pour" as if on sports cars with a low center of gravity.
Suspension based on adaptive rear levers
But engineers from Hyundai in improving adaptive suspensions are not going on, but rather chose another path, making adaptive ... rear suspension levers! This is an Active Geometry Control Suspension system, that is, active control of suspension geometry. In such a design, for each rear wheel, a pair of additional levers with electric drives, which vary the convergence depending on the conditions of movement.
Due to this, the leaning of the car is reduced to the drift. In addition, due to the fact that the inner wheel is content in turn, this cunning reception simultaneously is actively struggling with insufficient turning, performing the function of the so-called full-controlled chassis. In fact, the latter can be safely recorded to adaptive car suspension. After all, this system in the same way adjusts to various conditions of movement, contributing to improving the controllability and stability of the car.
Full chassis
For the first time, full chassis installed almost 30 years ago on Honda Prelude, but that system could not be called adaptive, since it was completely mechanical and dependent on the rotation of the front wheels. In our time, the electronics will be headed, therefore there are special electromotors on each rear wheel (actuators), which rolls a separate control unit.
Prospects for the development of adaptive suspension
Today, engineers are trying to combine all invented adaptive suspension systems, reducing their mass and dimensions. After all, in any case, the main task driving by car suspension engineers, such: the suspension of each wheel at each moment of time should be their unique settings. And how we can clearly see, many companies have succeeded quite strongly.
Alexey Dergachev
Magnetic racks and shock absorbers Cadillac Magnetic Ride Control are designed to improve controllability and improve comfort when driving on roads with different types of coatings. The system appeared quite a long time and turned out to be so effective that in the future many other European and German automakers repeated, but initially it appeared on Escalade, SRX, STS models.
Operating principle
In general, the system works simple enough. Unlike traditional shock absorbers, in the shock absorbers of this species, it is not used butter or gas, but a magnetic rheological fluid that reacts to a magnetic field created by a special electrical coil located in the case of each shock absorber. As a result of exposure, the density of the liquid changes, and, accordingly, the stiffness of the suspension.
The Magnetic Ride Control system works very quickly, data from different sensors come at a speed of up to a thousand times per second, which is instantly reacting to the change in the road surface. Sensors measure body splits, acceleration of the car, loading and other data, based on which the current is calculated, which comes separately to each of the shock absorbers at the moment.
In fact, everything happens exactly as describes the manufacturer, good handling is combined with a high level of comfort. But there is a significant lack of operation in our country.
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Adaptive suspension (Other Name semi-active suspension) - a type of active suspension, in which the degree of damping shock absorbers changes depending on the state of the road surface, motion parameters and driver requests. Under the degree of damping is understood as the rapidness of oscillations, which depends on the resistance of the shock absorbers and the magnitude of the undercorns. In modern designs, adaptive suspension uses two methods for regulating the degree of damping shock absorbers:
- with the help of electromagnetic valves;
- using magnetically rheological fluid.
When adjusting, using an electromagnetic adjustment valve, its passage section changes depending on the values \u200b\u200bof the acting current. The larger the current, the smaller the flowing section of the valve and, accordingly, above the degree of damping of the shock absorber (rigid suspension).
On the other hand, the smaller the current, the greater the passage cross section of the valve, below the degree of damping (soft suspension). The adjusting valve is installed on each shock absorber and can be located inside or outside the shock absorber.
Shock absorbers with electromagnetic adjustment valves are used in the design of the following adaptive suspension:
Magnetically rheological fluid includes metal particles, which, when exposed to a magnetic field, are built along its lines. In the shock absorber filled with magnetic and rheumatic fluid, there are no traditional valves. Instead, there are channels in the piston, through which fluid is fluid. Electromagnetic coils are also built into the piston. When the voltage coil is applied to the voltage coils, the particles of the magnetic and rheumatic fluid are built over the magnetic field lines and create resistance to the movement of the fluid on the channels, which increases the increase in the degree of damping (suspension stiffness).
Magnetically rheological fluid is used in the adaptive suspension design significantly less often:
- Magneride from General Motors (Cadillac, Chevrolet Cars);
- Magnetic Ride from Audi.
Adjusting the degree of damping shock absorbers provides an electronic control system that includes input devices, control unit and actuators.
The following input devices are used in the operation of the adaptive suspension control system: road lumen sensors and body acceleration, operation mode switch.
Using the operating modes switch, the degree of damping the adaptive suspension is made. The traffic sensor captures the magnitude of the suspension of the suspension on compression and on the back. The body acceleration sensor determines the acceleration of the car body in the vertical plane. The number and nomenclature of the sensors differ depending on the design of the adaptive suspension. For example, in the DCC suspension from Volkswagen, two road lumen sensors and two body acceleration sensors are installed ahead of the car and one by one - rear.
Signals from sensors are transferred to the electronic control unit, where, in accordance with the laid program, they are processing and the formation of control signals to actuators - adjustment electromagnetic valves or electromagnetic coils. In operation, the adaptive suspension control unit interacts with various car systems: steering amplifier, engine control system, automatic gearbox and others.
In the design of the adaptive suspension, three modes of operation are usually provided: normal, sports and comfortable.
Modes are selected by the driver depending on the need. In each mode, automatic adjustment of the degree of damping shock absorbers within the established parametric characteristic.
The testimony of body acceleration sensors characterize the quality of the road surface. The more irregularities on the road, the more actively swinging the body of the car. In accordance with this, the control system sets up the degree of damping shock absorbers.
Traffic sensors track the current situation when the car moves: braking, acceleration, rotation. When braking, the front of the car is lowered below the rear, when accelerated, on the contrary. To ensure the horizontal position of the body, the adjustable degree of damping of the front and rear shock absorbers will differ. When the car is rotated due to inertial force, one of the parties is always higher than the other. In this case, the adaptive suspension control system separately regulates the right and left shock absorbers than the resistance when turning is reached.
Thus, based on the sensor signals, the control unit generates control signals for each shock absorber separately, which makes it possible to maximize comfort and security for each of the selected modes.
