The ABS system, which has such a good track record: does not allow the wheels to lock up, provides excellent handling and efficient braking on slippery road surfaces, also has significant disadvantages..
But it does not matter if another system is also installed on the car - EBD (Electronic Brake Force Distribution), which copes well with compensating for the shortcomings of ABS. So how does the brake force distribution system work and why is it needed?
What is ABS? And what are her shortcomings?
Anti-lock braking system per second can make 15 to 25 cycles braking. Even a mega professional in the field extreme driving due to physical factors is not able to carry out more than 5 braking per second.
The task of the ABS is to convert the driver's constant pressure on the brake pedal into a periodic one, which allows you to maintain control over the car. That is, the main task of ABS is to maintain controllability.
Yes, ABS is a great defense against "fools" and a strong support for inexperienced beginners, but there are also disadvantages:
During system operation, it is difficult to calculate and predict when it will stop, because braking is not actually controlled by the driver;
There may be delays in turning on the ABS, because for it to work correctly, it must test the road surface and calculate the tire adhesion coefficient with it. This is possible on slippery roads when driving at speeds over 130 km/h. This is important to know in order to be prepared and not get confused, thinking that the brakes have failed!
If there is a frequent alternation of uneven and uneven road surfaces, the system may not always respond correctly at what point and for which road to calculate the correct friction coefficient;
If the car jumped, the system suspends the braking force. This can lead to a sudden uncoordination of the driver at the time of inactivity of the ABS;
The anti-lock braking system eliminates even the smallest attempts to lock the wheels, which can cause discomfort on loose and loose surfaces;
ABS terminates its function at speeds up to 10 km/h. Yes, this is the norm passenger cars, but if we take into account heavy vehicles, for example, cash-in-transit or executive armored vehicles, then a distance of up to one and a half meters can be added to the braking distance, which can clearly lead to an accident.
How ABS works
ABS, in its way of working, is somewhat reminiscent of the behavior of an experienced driver behind the wheel of a car. For example, on an ice surface, when you need to intermittently slow down, keeping the wheels on the verge of blocking. In addition to all this, ABS aligns the work of the wheels, automatically adjusting the braking force. This happens at such a level that the car does not lose its exchange rate stability.
The complexity of the technical execution does not apply to the principle of operation of this system. After the driver presses the brake pedal, the brake mechanisms of the wheels are affected brake fluid. In the place of contact of automobile wheels with pavement brake forces begin to develop. If you continue to press the pedal, the braking effect will certainly increase, but only up to a certain point. If we further increase brake pressure, then positive results should not be expected, since the wheels are simply blocked, their rotation stops, and sliding, on the contrary, increases, although the impact braking forces remains at the same level.
As a result, the car becomes almost impossible to drive. ABS does everything necessary to ensure that you simply avoid such a development of events. Having received signals from the sensors and comparing them as necessary, the ABS control unit commands the control valve to reduce the fluid pressure in brake system no matter how hard you press the brake pedal. Important in the principle of operation of ABS and the fact that the system individually determines the braking of each wheel, which began to experience blocking. When the situation has stabilized and the blocking probability has passed, the brake fluid pressure is normalized to prevent underbraking of the wheels.
Each driver needs to know the difference between driving a car that is equipped with ABS and a car without this system. When driving a car with ABS, feel free to press the brakes, the wheels will not lock. Sometimes for drivers who have moved from old cars to models equipped with ABS, the process of getting used to is not easy. After all, earlier it was necessary to “play” with the pedal, but now you just need to press the brake to the floor.
How EBD works
EBD monitors the control of the distribution of braking force to all wheels. It operates on the data provided by the ABS block. Each wheel of a vehicle fitted with an EBD system is equipped with sensors that transmit the wheel speed by means of electrical signals. More system sensors read the pressure in each wheel, determining how much the car is loaded. In general, EBD has data on how fast the car is moving, how loaded it is and how good the contact of the wheels with a particular road surface is. A big plus is that the data is read separately and independently from each wheel. This allows you to distribute the braking actions as correctly as possible, avoiding losses in control.
The principle of operation of EBD can be characterized by the usual simple example of tug of war. As long as both teams are applying equal effort to tug, the rope is in a stationary position. But if at least one participant in the competition folds his hands, most of the rope will be on the side of the rivals. The analogy is visible in the case of EBD. In order to prevent the car from stalling into a skid, the electronics evenly distribute efforts to help the weakened wheel, if necessary, weakening others.
Difference between ABS and EBD
EBD is a kind of continuation, an assistant to ABS. The main difference between EBD and ABS is the fact that the driver is assisted not only during emergency braking, but also every time you press the pedal in normal situations. EBD always assists the driver in the management of any kind of braking. The EBD system analyzes the position of each wheel separately during braking, distributing the necessary force among them. Such a system works great when braking on turns on mixed surfaces, saving the directional stability of the car, in which the center of mass is shifted towards the outer radius of the wheels. In this case the forces of the brake system are distributed as between automobile axles and between all wheels. EBD is more effective at helping to maintain trajectory and minimize the likelihood of skidding than ABS.
History of EBD
The EBD system technology is not new enough. Its development by engineers began in the last century. And already in the late 80s, new cars were successfully equipped with this system. Developers working for the automotive giants have noticed that the ABS system does not fully cope with the task that is entrusted to it. Studies have shown that when braking, the main load is taken by the front wheels.
The anti-lock braking system, of course, prevented the wedge of the front wheels, but the rear ones remained without movement, which contributed to the skidding of the car.
Studies carried out in the design offices showed that the braking forces were evenly distributed between all the chassis of the car, but the wheels were subjected to completely different conditions. The fundamental factor was the adhesion of the wheels to the braking surface. As a result each wheel behaved individually. Due to the fact that the rear wheels were blocked, this led to the throwing of the car body from side to side. The free movement of the front wheels contributed to the driver's control of the car. All these indicators influenced the development and creation of the EBD brake force distribution system.
On what vehicles is it installed?
Anti-lock braking systems were originally planned to be used in the aviation industry, but to establish mass production failed on a large scale. Later, as you know, ABS began to be installed on cars and motorcycles.
Nowadays EBD in conjunction with ABS is installed on most trucks and cars
, motorcycles, in order to exclude the possibility of the driver flying over the steering wheel and even trailers.
The abbreviation EBD stands for "Electronic Brake Distribution", which means " electronic system brake force distribution. EBD works in conjunction with and is its software addition. It allows you to more effectively distribute the braking force on the wheels depending on the vehicle load and provides better controllability and stability when braking.
Principle of operation and design of EBD
Stopping distance with and without EBDDuring emergency braking, the center of gravity of the car shifts to the front, reducing the load on rear axle. If at this point the braking forces on all wheels are the same (which happens in vehicles that do not use brake force control systems), rear wheels can be completely blocked. This results in loss due to lateral forces, as well as skidding and loss of control. Also, the adjustment of the braking forces is necessary when loading the car with passengers or luggage.
In the case where braking is performed in a corner (with the center of gravity transferred to the wheels running on the outer radius) or arbitrary wheels hit surfaces with different grip (for example, on ice), the action of one ABS system may not be enough.
This problem can be solved by the brake force distribution system, which interacts with each wheel separately. In practice, this includes the following tasks:
- Determining the degree of slippage on the road surface for each wheel.
- Changing the pressure of the working fluid and the distribution of braking forces depending on the adhesion of the wheels to the road.
- Preservation of course stability under the influence of lateral forces.
- Reducing the likelihood of the car skidding during braking and turning.
Main elements of the system
The layout of the elements of EBD (ABS) in the design of the car Structurally, the brake force distribution system is implemented on the basis of the ABS system and consists of three elements:
- Sensors. They record data on the current rotational speed of each wheel. In this case, EBD uses ABS sensors.
- Electronic control unit (control module common to both systems). Receives and processes speed information, analyzes braking conditions and actuates the appropriate brake valves.
- Hydraulic block of the ABS system. Performs pressure adjustment in the system, changing the braking forces on all wheels in accordance with the signals given by the control unit.
The brake force distribution process
The distribution of braking forces along the axes of the car In practice, the operation of the electronic brake force distribution system (EBD) is a cycle similar to the operation of the ABS system and consists of the following steps:
- Analysis and comparison of braking forces. It is carried out by the ABS control unit for the rear and front wheels. If the specified value is exceeded, the algorithm of actions pre-installed in the memory of the EBD control unit is activated.
- Closing valves to maintain the set pressure in the wheel circuit. The system determines the moment when the wheel lock starts and fixes the pressure at the current level.
- Opening exhaust valves and reducing pressure. If the risk of blocking the wheels persists, the control unit opens the valve and reduces the pressure in the circuits of the working brake cylinders.
- Increasing pressure. When the wheel speed does not exceed the lock threshold, the program opens the intake valves and thus increases the pressure in the circuit created by the driver when the brake pedal is pressed.
- At the moment the front wheels start to lock, the brake force distribution system is turned off and ABS is activated.
Thus, the system continuously monitors and most effectively distributes the braking force on each wheel. However, if the car is carrying luggage or passengers on rear seats, the distribution of forces will be carried out more evenly than with a strong shift in the center of gravity to the front of the car.
Advantages and disadvantages
The main advantage is that the electronic brake force distribution allows the most efficient use of the braking potential of the car, depending on external factors (loading, cornering, etc.). At the same time, the system works automatically, and it is enough to press the brake pedal to start it. Also, the EBD system allows you to brake during long turns without the risk of skidding.
The main disadvantage is that, in the case of using studded winter tires, when braking using the EBD brake force distribution system, compared to conventional braking, the braking distances. This minus is also typical for classic anti-lock systems.
In fact, the electronic brake force distribution system (EBD) is an excellent addition to ABS, making it more advanced. It comes into operation before the start of the anti-lock braking system, preparing the car for more comfortable and efficient braking.
When reviewing the modern car market and buyers, the question arises, what is EBD in a car and what function does a system with this abbreviation perform. The abbreviation EBD stands for Electronic brake-force distribution (in German models EBV - Elektronishe Bremskraftverteilung) is a brake force distribution system, is a software addition to the familiar for many motorists traction control system(ABS).
Unlike pure ABS, ABS + EBD controls the behavior of the car in all driving modes, including emergency braking. It is important to understand that EBD is not a mechanism, but a specially designed software, a kind of ABS action controller. Leading car manufacturers have been installing the EBD system on cars (not only cars, but also motorcycles and heavy trucks) since the early 90s, when it was noticed that the classic anti-lock braking systems installed on new models often do not cope with their tasks and perform incorrect actions. which can lead to disastrous consequences.
Illustration of brake force distribution using EBD (Electronic brake-force distribution)
EBD is a system that, by distributing brake forces to different wheels, helps the driver to keep the car on the desired path. When cornering, the system does not allow the machine to skid or dangerously change the trajectory of movement (stall). Another task of the EBD is to regulate the behavior of the anti-lock braking system on mixed roads, optimize its effect and prevent excessive or insufficient electronic intervention in the control process.
Here are some examples of when an EBD system can be useful:
- During emergency braking.
- When braking on mixed surfaces. For example, when driving on one side of the car to the side of the road or an area with a surface other than the road.
- When braking when turning - the distribution of the load on the brakes to maintain the balance of the car.
How EBD works
Electronics using sensors determines the change in the speed of a particular wheel or pair of wheels, which occurs when the car hits a difficult surface, for example, an area with ice or water. By analyzing data from sensors, the EBD system determines the degree of adhesion to the roadway of each of the wheels and decides on the distribution of braking force. After that, the valves receive a command to increase or decrease the work of the brake discs. After balancing the braking forces, the EBD stops working and allows the driver to freely maneuver and change the trajectory of movement.
Video about EBD
Benefits and contribution to safety
The EBD system has no pronounced disadvantages, and experts note a number of advantages in its use:
- the optimal choice of the coefficient of adhesion with the road of the rear wheels under any road conditions;
- control and improvement of the work of ABS, increasing the stability of the car;
- wear reduction brake pads and disks, increasing their service life, compliance with temperature operating conditions;
- reduction in the required effort when the driver presses the brake pedal.
The International Committee on Traffic Safety at the UN noted the invaluable contribution of EBD to the work of ensuring safety traffic and preserve the health and life of motorists, passengers and pedestrians.
For a long time, the automotive industry supplied vehicles based solely on the laws of mechanics. meet today modern car, which will not be stuffed with a large number of computers and a variety of auxiliary electronics is almost impossible. In other words, fifty percent of the safest cars these days are controlled by artificial intelligence.
This applies in particular to vehicle security systems. Every year, braking, anti-lock, anti-slip systems are becoming more advanced and high-tech, providing safe driving even for beginners.
One of the revolutionary innovations at the time was the EBD system, which is responsible for the distribution of braking forces.
The brake distribution system or Electronic Brake Distribution (EBD) was first used in the early nineties of the last century. Even then, most car manufacturers accepted the fact that their ABS systems do not give one hundred percent results in terms of completely unlocking the wheels while driving. This was especially evident when it came to the distribution of the load on the brakes of the front and rear wheels. ABS easily coped with unlocking the front wheels, but the rear wheels could not be unlocked more often, which instantly led to a dangerous turn of the car while driving at speed.
After several years of research, it was found that all wheels receive the same braking load. But the problem was that at the same time they were all in different conditions and had different grip. Thus, with the same load, all four wheels could behave completely differently, creating an emergency while driving. The front ones could be unlocked, giving the driver more control over the car, but the rear ones, which could not be unlocked, completely offset the effect, sending the car into a skid. To solve this complex problem, the EBD system, an electronic brake force distribution system, was created.
Today, EBD can significantly improve the car's handling and can really return the driver to control vehicle. Thanks to this system, the trajectory of movement is maintained, the degree of likelihood of skidding is reduced even on slippery surfaces. Electronics easily determines how great the grip is, on what surface the movement takes place. After that, there is a direct distribution of braking forces, which allows you to remove the braking load from the wheels, which have good grip.
The whole system is built on the work of three main basic elements. The first is sensors that take into account how fast the wheels are spinning. The same sensors are used by the ABS system to obtain the necessary information. The second element is the valve system of the brake line, consisting of pressure reducing and check valves. The third is the ABS control unit, with which the EBD is inextricably linked.
The essence of the work is the timely receipt of signals from the ABS and the correct response to them. As soon as the car is in a state of emergency braking, the ABS system is activated. At the same moment, the work of the brake force distribution system begins, which, taking all the necessary data from the sensors, determines how fast the wheels of the car are spinning.
After receiving and processing the data, EBD calculates which of the wheels have normal traction and which do not. After that, the distribution system itself comes into force - signals are sent from the block to the valves that are responsible for regulating the pressure in the car's brake system. They distribute the braking force so that the front wheels receive less of it. In this case, most of the effort goes to the rear wheels. This achieves the effect of leveling the effort, which allows you to improve handling, grip and return control of the car to the driver, thereby preventing an accident.
At the same time, the ABS continues to work, which, focusing on the data on the correctly distributed braking force, begins to unlock the wheels. Often this allows (in 99 percent of cases) to avoid a collision of a car with an obstacle on the way.
What is the difference between ABS and EBD? The answer is pretty simple. If the ABS works only at certain times, then the brake force distribution system is always on. It processes all the data of the brake system every second, “understanding” also the surface on which the car is moving. That is, in fact, the system also works in those moments when there is not even a hint of an emergency, constantly processing data from sensors in the braking system. At the same time, in modern cars ABS and EBD are two safety elements that work not so much in conjunction as complement each other.
No matter how it sounds, but at the moment there is simply nothing to say about the shortcomings or disadvantages of the brake force distribution system, since in fact there are none. On the other hand, there are several advantages to using EBD.
First of all, this system provides the most safe management vehicle even on difficult surfaces. The driver may not be afraid that he will be blown off the road or turned around, moving on very slippery asphalt.
EBD shows excellent results both when braking on a straight line, and during emergency braking during a sharp turn or a dangerous skid. Moreover, in the second case, modern systems are able to distribute the braking force not only between the front and rear wheels, but also focusing on the situation and the drift angle between the inner and outer pair of wheels, providing a quick return of control over the car to the driver.
Since the introduction of electronics into the automotive industry, cars have been equipped with an increasing number of auxiliary systems controlled by electronic intelligence. This, in particular, applied to active safety car: the designers have improved the braking system, providing it with an anti-lock system, which helped to avoid blocking the wheels in emergency situations. The evolutionary development of active safety systems related to braking was the emergence of another mechanism - the brake force distribution system.
What is EBD
EBD (Electronic Brake Distribution), which in Russian means "brake force distribution system", began to appear on cars in the late 1980s and early 1990s. It was then that the leading engineers automotive companies noticed that the anti-lock braking system cannot provide a 100% wheel unlocking effect. This became especially noticeable when, during braking, the front wheels received a greater load than the rear ones. At the same time, the system successfully unlocked the front wheels, but the rear ones remained blocked, which caused the car to turn. After conducting research, experts found that the braking force that develops in such a situation is distributed equally between all wheels. But the wheels at the same time are in different conditions - their grip on the road surface is different, therefore, they behave differently: for example, the front wheels are unlocked and "allow" the driver to drive the car, and the rear wheels are locked, which causes the car to skid . To solve this problem, a brake force distribution system was developed.
EBD consists of three main components: wheel speed sensors (the same sensors are used from which ABS receives information), electronic block control (again, in common with ABS), and valves in the brake line - return and reduction. When the car brakes in an emergency and the ABS is activated, the brake force distribution system is automatically activated. Its control unit receives information from sensors about how fast the wheels rotate. Based on this data, the system concludes which wheels have the best grip and which have the worst. Then the process of distributing brake forces takes place: the control unit gives a command to the valves, which, by regulating the pressure in the brake system, distribute the braking force - the front wheels receive less, the rear wheels receive more. Thus, the force on all wheels is equalized.
At the same time, the ABS system, having received a signal that the braking force is evenly distributed, unlocks the wheels, and this allows the driver to gain control over handling and avoid an obstacle.
The main difference between EBD and ABS is that this system works constantly, controlling the distribution of braking forces, regardless of road conditions and driver activity, and not only in extreme conditions, like the same ABS. However, today often cars equipped with an anti-lock braking system also have a brake force distribution system - these mechanisms are so integrated and complement each other.
Advantages and disadvantages of EBD
This system has no operational deficiencies. But EBD has many advantages. After all, by distributing the braking force between the wheels, the system helps the driver to save the trajectory of driving, reduces the risk of drifting or skidding. It is equally effective both in straight-line braking and in braking in sharp turn. In the latter case, the system distributes the braking force not between the front and rear wheels, but between the wheels on the outer and inner turning radius.