Adaptive suspension (Other Name semi-active suspension) - a type of active suspension, in which the degree of damping shock absorbers varies depending on the state road coat, 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:
- via 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 flowing 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.
Regulating the degree of damping shock absorbers provides electronic system Management, which includes input devices, control unit and actuators.
The following input devices are used in the adaptive suspension control system: Sensors road Suit and accelerate the body, switch 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 Tracking current situation When driving a car: braking, acceleration, turn. 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 adjusts 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.
From the day the first car appears, engineers do not stop in an attempt to create an ideal car. At the same time, one of the main tasks that stood before the great minds was the development of a safe and universal suspension capable of adapting to road conditions. And the efforts were rewarded. In 1954, it was possible to release the first car equipped with a hydropneumatic (adaptive) suspension.
Purpose
Why do you need a hydropneumatic suspension? Engineers have created an adaptive mechanism that can adapt to the coating and driving style. The main components of the device are hydropneumatic units that differ in high elasticity. The role of elements is the working fluid and gas under pressure in the containers intended for them.
Adaptive suspension makes the movement of the car smooth and, if necessary, changes the position of the body relative to the road surface. Hydropneumatic suspension is often "mixed" with other suspension types. A bright example is a car of the French company Citroen C5. Two pendants coexist in it - adaptive and classic MacPherson (front) and multi-dimensional suspension type from behind.
History
As already mentioned, the first car with an adaptive suspension was able to create in 1954, and after a year the novelty appeared on the Motor Show Paris. The design of the node produced a furor among the connoisseurs of the automotive world. For those times, the machine with a hydropneumatic suspension seemed miracle. Regardless of the number of passengers or filling the trunk, the auto maintained the initial clearance and showed the smoothness of movement. It has the opportunity to hang the wheels without the use of the jack.
The function also deserved a function that gives the ability to adjust the clearance of the car. For France, with its country roads, such an option was very useful. Adaptive suspension increased the level of safety even when driving through strong ughabam.
The appearance of a new device has become the beginning. Citroen's engineers did not stop, and in 1989 they created an adaptive suspension of Hydractive 1, which applies today. The advantage of the new design is the presence of an electronic "filling", which allows you to control the road situation and adapt to it.
Four years have passed and the brand cars were equipped updated suspension Hydractive 2. Even after seven years (in 2000), the world saw an adaptive suspension Hydractive 3. The new design was distinguished by unique characteristics and was divided from brake system (In the second "part" of the brake and suspension interacted with each other).
Hydropneumatic suspension is installed not only on Citroen machines. New technology They intercepted such brands like Rolls Royce, Bentley, Mercedes and others. In the last 5-10 years, this list has been replenished with a number of other models.
Device
The adaptive suspension consists of a group of nodes, each of which carries its functional load:
1. Hydroelectron Block (the second name of the node - hydrotronique). The task of the device is to submit the required volume of the workforce and guarantee the required pressure. This node combines the following elements:
- electric motor;
- ECU ("brains" of adaptive suspension);
- axial piston pump;
- electromagnetic valves, adjusting car clearance;
- protective valve;
- stop valve. The task is to protect the body from lowering the clearance in a non-working position.
ECU and EM valves - Hydro control system pneumatic suspension.
2. Capacity for the working mixture is located above the hydropower node. In vehicles with adaptive suspension, the hydraulic 3 is trying on the LDS fluid having a bright orange color. Before that was used green liquid LHM.
3. The front suspension stand is a device in which a hydraulic cylinder and a hydropneumatic elastic node are combined. The design elements are connected through the depreciation valve, which effectively extinguishes the oscillation of the body part.
4. Elastic assembly, working on a hydropneumatic principle, is a metal spherical design. Inside there is an elastic membrane, over which nitrogen is located (compressed gas). Under the partition contain special compositiontransmitting pressure system. In this case, the gas, like a filler, plays the role of an elastic element.
In adaptive pendants of the Hydractive 3+ series, mounted one by one elastic node on the wheel and by additionally a spherical design for each of the axes. The use of mentioned elements is the ability to expand the suspension hardness control levels. At the same time, the lifetime of special spheres - 200 thousand kilometers of run and more.
Hydraulic cylinders - a group of nodes that ensure the filling of the fluid of elastic elements, as well as a change in the height of the body relative to the road. The main device of the hydraulic cylinder is the piston. The rod of the latter is combined with the "his" lever of the suspension. Hydraulic cylinders, located in front and rear, have an identical design. The only difference is that the rear knot is located at a low angle to the surface of the road.
Stiffness control - node, with which the stiffness of the suspension is adjusted. It includes:
- Uh valve for direct adjustment;
- additional shock absorber valves;
- spool.
Stiffness control is mounted on both suspensions. At the same time, two modes are possible:
- "Soft" mode. In this case, the regulator combines hydropneumatic nodes in such a way as to ensure optimal gas pressure. At the same time, the EM itself remains without tension;
- the hard mode is activated when a voltage is applied to the node. In this case, the rear cylinders, racks and auxiliary spheres are isolated from each other.
The adaptive suspension control system consists of the following nodes:
- input devices. Two mechanisms are included here - the modes switch and the input sensor group. The latter transform removable characteristics into electricity. One of the main sensors of the system controls the position of the body part (relative to the surface) and the angular steering sensor.
In Citroen cars, 2-4 body position sensors are mounted. As for the second input device (angular steering sensor), it betrays the data on the speed of turning and the direction of the steering wheel.
The special switch makes it possible to adjust the rigidity and body height manually;
- ECU - "brains" of systems that collect signals from the input nodes conduct their processing and taking into account the specified algorithm send commands to the executing authorities. In his work, the ECU is in interaction with ABS and the system of controlling the power node;
- executive knots - Devices that execute commands from the computer. These include EM valves of stiffness and height adjustment, electric motor pump hydraulic system, headlight corrector.
The electric motor is controlled by the control unit, changes the speed of rotation, pump performance and pressure in the system. Adaptive suspension is especially presence of four EM valves regulating height. The first pair lifts the front suspension, and the second pair is rear.
Operating principle
Design elements interact in the following algorithm:
- Hydropneumatic cylinders catch liquid to elastic elements. Hydblock keeps under control pressure and fluid volume. When the fluctuations appear, the fluid passes through the valve, which is quenched by oscillation.
- The soft mode implies the combination of elements with each other and the creation of the maximum volume of gas. At this stage, rolls compensation and maintenance of the necessary pressure occurs.
- If you need to turn on the hard mode to the system, voltage is supplied. After that, additional spheres and front suspension rack are separated by each other. At the moment of rotation, the rigidity changes for each specifically taken node. In the process of rectilinear movement, rigidity changes.
Alternative options
A hydropneumatic system from the Hydractive series is not the only development. Mercedes introduced the market similar to the design - Active Body Control. The principle of action is almost identical. The hydraulic cylinders are pressed the springs, the pressure change occurs, the desired position and rigidity are set.
Adaptive suspension was developed by Volkswagen. Her name is Adaptive Chassis Control. The node provides control of the settings through the sensors and corrects the rigidity of the chassis.
Advantages and disadvantages
Hydropneumatic suspension is not an embodiment of the ideal. It adds comfort and convenience, but there are disadvantages in it.
Benefits:
- the possibility of adjusting the clearance manually increases the car's passability, simplifies the parking process, unloading and loading, as well as cleaning vehicle;
- the presence in some systematic adjustment is more convenient operation;
- improving the comfort of the trip provided by smoothness of the course. If you believe the reviews, then the machine seems to be floating on water, and does not move on solid coating;
- adjust the driving style and coating on the road.
Cons adaptive suspension:
- the complexity of the design, which promises the cost of repair and the rise in price of the car when buying;
- the reliability of adaptive suspension is less than that of classic structures.
- This type of suspension is "tenderness", therefore requires proper operation.
RESULTS
Hydropneumatic (adaptive) suspension - a breakthrough in the field of automotive industry. With its appearance, it was possible to solve the mass of problems with handling, clearance and adjustment under the style of driving. The main problem The price remains, due to which the "budget" manufacturers still prefer accessible pendants.
Any car is equipped with a suspension - the movement without it would be quite difficult and uncomfortable. The main element in a simple suspension is a spring that takes on the main blow from the wheel meeting with the pavement defects. At this moment it is compressed, but then the absorbed energy is given, and a shock absorber is provided for absorption. The mode of operation of the standard suspension is always the same.
AVS Adaptive Adjustable Suspension is somewhat different - it is able to adapt to specific road conditions. Stiffness can be changed by means of a control unit located in the cabin. Such a system allows you to improve car handling, reduce fuel consumption and rubber wear. Thus, when driving on a level highway, a rigid suspension will be relevant, providing car stability when maneuvering at high speeds. When moving at low speed on Ughabam, comfort increases with a decrease in rigidity.
Adaptive suspension system
Each automaker, establishing an adaptive suspension into his cars, calls it differently, but the meaning of this does not change. The degree of rigidity of the active suspension is subject to adjustment in just two ways:
- by valve S. electromagnetic control;
- with a liquid with magnetic and rheological properties.
The solenoid valve is capable of changing its passage hole depending on the current flow coming to it. If necessary, make the suspension with a more rigid on the valve you need to give a high voltage current, which significantly slows down the circulation working fluidAnd the suspension is made as hard as possible. When the low voltage current is submitted, the suspension is made as soft as possible, since the hydraulic fluid has the ability to relatively free circulation.
The suspension based on magnetic rheumatic fluid functions somewhat differently. The fluid itself containing special metal particles is capable of changing its properties under the influence of an electromagnetic field. Suspension has special shock absorbers that do not contain traditional valves - they are replaced by special channels for fluid circulation. They have shock absorbers and mounted coils housing generating the electromagnetic field, under which the properties of the fluid are changed, which allows you to change the damping parameters.
Modes of work
Adjusting the degree of hardness of adaptive suspension TC occurs almost fully automatically. The entire adjusting system consists of the following main elements:
- control block;
- input devices - road lumen sensors and body acceleration;
- executive devices - valves and coils of the shock absorbers themselves.
As a rule, the system has a mode switch located in the cabin that allows a person to choose the preferred hardness mode, in accordance with the specific conditions. When moving, the control unit constantly reads signals from all sensors, analyzes the degree of shock absorbers and emerging body rolls. The number of sensors may differ depending on the brand of the car, but they should be at least two - ahead and rear.
The received signals are processed, and signals are formed for actuating devices in accordance with the program chosen by the driver, which, as a rule, three is normal, comfortable and sports. For the more correct operation of the adaptive suspension, its control unit is constantly "collaborating" with other auto systems: steering, gearbox, engine control system. This achieves the most clear operation of the active suspension.
Advantages of active suspension
Any car equipped with an adaptive suspension has a lot of advantages over the car with its standard option. The main advantages of adaptive suspension must include the following:
- significantly increased comfort for the driver and passengers;
- little rubber wear;
- excellent car handling at high speed, when making sharp maneuvers;
- reduced brake path on any road surface.
The sensors respond for the suspension reaction rate. It is they who constantly monitor the position of the body, which changes with sharp acceleration / braking, when drove in turn, especially cool. The level of damping of suspension elements when losing the body of its correct position will immediately change. This achieves permanent maintenance of an exclusively horizontal position of the body, which allows you to maintain full control over the car. More about the work of such a system can be viewed on video:
An important aspect in the operation of the active suspension system was its interaction with other auto systems. Thus, the change in the mode of operation of the suspension not only changes the characteristics of the shock absorbers themselves, but the settings of the gas pedal, steering, dynamic stabilization systems are changed independently. This allows not only to get more secure, but more simple to control the car. Depending on the specific manufacturer, the adjustable suspension can also take into account the loading of the vehicle.
Any car equipped with active suspension, has a lot of advantages on the road, compared to standard options. At the same time, many automakers provide for automatic configuration of the suspension operation in standard mode - the driver does not need to constantly switch the modes, the system itself will adjust the optimal rigidity depending on the amount of irregularities on the road, the degree of acceleration, and a number of other parameters.
Before you start talking about such a mechanism as adaptive suspension, you need to figure out what the suspension is. It was created in order to be a buffer between the body of the car and expensive.
If the car had no suspension, then all shocks, jumps and other irregularities would be transmitted straight on the body, which would be very bad to affect the overall condition of transport.
Among the elements of the suspension there is a spring. When the wheels are encouraged with irregularity, it assumes almost all the energy from the collision and shrinks. But after squeezing, the spring will push the energy back, which leads to the swaying of the car. And immediately after that, shock absorbers are included in the work, which are designed to absorb all energy due to resistance. It is also worth saying that the shock absorbers are transformed into thermal.
Features adaptive suspension
Manufacturers of different car brands make a considerable number of suspension, which are divided into various options for one or another functions. Adaptive suspension is known to most motorists as an active suspension. And what is the principle of action of such a suspension? It can adjust the conditions that are available on the road.
It is also noteworthy that, if necessary, the hardness of this suspension can be changed using a control unit that is placed in the cabin.
It is worth saying that AVS abbreviations use only such brands like Lexus and Toyota. But this does not mean that other brands do not produce this mechanism. They simply call these suspensions in their own way, and it is important to consider, because motorists are often confused in such a situation.
By itself, this mechanism is very complicated in terms of construction. To create it, the best specialists are selected. And if something with such a suspension goes wrong, it is better to go to the service and contact the specialists.
Suspension options
And now you need to consider the most interesting options for such suspension. And the first in the queue will be the shock absorber damping system. Now in stores sell the suspension in two versions:
- magnetic rheological fluid;
- electromagnetic valve with regulation.
The variant containing the liquid is based on the effect of electric current. Liquid need to buy special, namely, in which small metal particles are present. And when the electromagnetic field will be created, these metal elements will be lined up in a strict order. And in the second case, when the impact will begin to the valve, the conductive holes will either shrink, or increase, thus changing the stiffness of the suspension.
The second option is an adaptive suspension from the BMW brand. It is called Dynamic Drive. If this mechanism is installed on BMW, then the comfort indicators will be very good, but not the fact that it will be just as good and on other brands of cars. Sensors that are located both in front and in the back of the body can react and adjust the desired stand. And this, in turn, completely removes the clink when braking or strong slopes during turn. Tests showed that this system reacts very well during some emergency stop. During the ride, the driver can choose one of the three versions of movement: normal, comfortable and sporty.
Also worth attention can be called the system dynamic control. Such a system can most often be seen on the Opel brand cars. Noteworthy is that it is possible to adjust each rack separately. In the new generations of cars, the adaptive suspension from this manufacturer provides 4 versions of the movement: soft, sports, dynamic and comfortable. It is also worth saying that when changing modes, the system changes not only the amortized characteristics, but also dynamic stabilization with the steering control.
For Porshe cars, an active suspension was created. It, compared to the previous, very "smart", completely connects all the mechanisms with the main computer. The active system, before making an execution decision, takes into account the readings from all sensors, speed, angle of rotation and even tire pressure. After all the information is collected, the system gives the Valve command on the racks.
Installation B. modern cars The suspension is a compromise between comfort, stability and handling. The suspension with increased rigidity guarantees the minimum level of the roll, respectively guarantees comfort and stability.
The soft suspension is characterized by a smoother course, with the execution of maneuvers, the car is swinging, which leads to an increase in instability and deterioration of controllability.
Therefore, autocontracers seek to develop the latest design of the active suspension.
The term "active" implies such a suspension, the main parameters of which are changed during operation. The electronic system embedded in it allows you to change the desired parameters in automatic mode. The suspension design can be divided by its elements, each of which changes the following parameters:
Some design types are used immediately into several elements. Most often, shock absorbers are used in the active suspension variable degree damping. Such a suspension has an adaptive suspension name. Often, this type is called a half-active suspension, due to the fact that it does not have additional drives.
To change the damping ability of the shock absorbers, two methods are involved: the first - the use of electromagnetic valves, as well as the presence special fluid magnetic rheological type. It is filled with the shock absorber itself. Managing the degree of damping of each shock absorber individually and is carried out. electronic block Control.
Famous suspension designs of the above described adaptive type are:
- Adaptive Chassis Control, DCC (Volkswagen);
- Adaptive Damping System, ADS (Mersedes-Benz);
- Adaptive Variable SuspenSion, AVS (Toyota);
- Continuous Damping Control, CDS (OPEL);
- ELECTRONIC DAMPER CONTROL, EDC (BMW).
An optional suspension version in which special elastic elements are implemented are considered the most versatile. It allows you to constantly maintain the necessary height of the body and the rigidity of the suspension system. But in terms of constructive featuresShe is tougher. Its cost is significantly higher as the repair. In addition to the traditional springs, hydropneumatic and pneumatic elastic elements are installed in it.
Active Body Control suspension, ABC from Mercedes-Benz adjusts the hardness level using hydraulic drive. For its work in the rack of the shock absorber under high pressure, oil is injected, and the hydraulic fluid is affected by a coaxially located spring.
The control unit of hydraulic cylinders of shock absorbers receives data from 13 different sensors, among which the sensors of the longitudinal acceleration, body position, pressure. The presence of the ABC system practically eliminates the occurrence of body rolls when turning, braking and acceleration. When raising the speed of cars more than 60 km / h, the system in automatic mode lowers the car by 11 mm.
The pneumatic suspension is based on a pneumatically elastic element. Thanks to it, it becomes possible to change the height of the body relative to the roadbed. The pressure is injected into the elements by means of a special electric motor with a compressor. The stiffness of the suspension is changed using dampy shock absorbers. It is for this principle that the Airmatic Dual Control suspension was created from Mercedes-Benz, it uses the Adaptive Damping System.
Hydropneumatic suspension elements allow you to adjust the body height and suspension stiffness. The suspension is adjustable using high pressure hydraulic. The hydraulic system operates from electromagnetic valves. One of the modern examples of such a suspension is considered to be a third-generation Hydractive system, which is installed on Citroen's production cars.
A separate category of active type suspension includes structures, which contains transverse stability stabilizers. They are in this case and are responsible for the stiffness of the suspension. Moving straightly, the stabilizer does not turn on, the moves of the suspension increase. Thus, the controllability on the uneven road improves. When performing turns or rapid changes in the direction of movement, the stiffness of the stabilizer increases, thereby preventing the occurrence of body rolls.
The most common types of suspension are:
- Dynamic Drive from BMW;
- Kinetic Dynamic Suspension System, KDSS from Toyota.
An interesting version of the active suspension is installed on hyundai cars. This is a system active control Suspension geometry (Active Geometry Control Suspension, Agcs). It implements the ability to change the length of the levers. They affect the indicators of convergence rear wheels. When moving directly and perform maneuvers at low speed, the system selects minimal convergence. When performing maneuvers at high speed leads to an increase in convergence, thereby improving handling. The AGCS system interacts with the system of coursework stability.
