What is a car electronic brake system?

Electronic brake system

Probably every driver knows what the ABS electronic brake system is. The anti-lock braking system was invented and first launched by Bosch in 1978. ABS prevents wheel lock during braking. As a result, even in the event of an emergency stop, the car remains stable. In addition, the car remains steered during braking. However, with the increasing speed of modern cars, one ABS was no longer enough to ensure safety. Therefore, it was supplemented by a number of systems. The next step to increase the braking performance after ABS was the creation of systems that reduce the brake response time. The so-called brake systems to assist braking. ABS makes braking with the pedal fully depressed as efficient as possible, but cannot work when the pedal is lightly depressed.

Brake booster

The brake booster provides emergency braking when the driver sharply presses the brake pedal, but this is not enough. To do this, the system measures how quickly and with what force the driver presses the pedal. Then, if necessary, immediately increase the pressure in the brake system to the maximum. Technically, this idea is implemented as follows. The pneumatic brake booster has a built-in rod speed sensor and an electromagnetic drive. As soon as the signal from the speed sensor enters the control center, the rod moves very quickly. This means that the driver sharply strikes the pedal, an electromagnet is activated, which increases the force acting on the rod. The pressure in the brake system automatically increases significantly within milliseconds. That is, the stopping time of the machine is reduced in situations where everything is decided from the moment.

Efficiency in the electronic brake system

Thus, automation helps the driver achieve the most effective braking. The effect of a brake agent. Bosch has developed a new braking system prediction system that can prepare the braking system for emergency braking. It is paired with adaptive cruise control, whose radar is used to detect objects in front of the car. The system, having determined the obstacle in front, begins to slightly press the brake pads to the discs. Thus, if the driver presses the brake pedal, he will immediately receive the fastest response. According to the creators, the new system is more effective than the usual Brake Assist. In the future, Bosch plans to implement a predictive security system. Which is able to signal a critical situation ahead with the help of vibration of the brake pedals.

Dynamic electronic brake control

Dynamic brake control. Another electronic system is DBC, Dynamic Brake Control, developed by BMW engineers. This is similar to the Brake Assist systems used, for example, in Mercedes-Benz and Toyota vehicles. The DBC system accelerates and increases the pressure increase in the brake actuator in the event of an emergency stop. And this ensures a minimum braking distance even with insufficient effort on the pedals. Based on data on the rate of pressure increase and the force applied to the pedal, the computer determines the occurrence of a dangerous situation and immediately sets the maximum pressure in the brake system. This greatly reduces the stopping distance of your car. The control unit additionally takes into account vehicle speed and brake wear.

Electronic brake system DBC system

The DBC system uses the principle of hydraulic amplification, not the principle of vacuum. Such a hydraulic system provides a better and significantly more accurate dosage of braking force in the event of an emergency stop. In addition, the DBC is connected to ABS and DSC, dynamic stability control. When stopped, the rear wheels are unloaded. In corners, this can cause the rear axle to slip due to the increasing load on the front axle. CBC works in conjunction with ABS to counteract rear axle deflection during cornering braking. CBC provides optimal brake force distribution in corners, preventing slippage even when brakes are applied. Operating principle. Using signals from the ABS sensors and determining the wheel speed, SHS controls the increase in braking force for each brake cylinder.

Electronic brake compensation

So it grows faster on the front wheel, which is external to the rotation, than on other wheels. Therefore, it is possible to act on the rear wheels with high braking power. This compensates for the moments of forces that tend to rotate the machine around a vertical axis during braking. The system is put into operation constantly and invisibly to the driver. EBD system, electronic brake force distribution. The EBD system is designed to redistribute the braking forces between the front and rear wheels. As well as wheels on the right and left side of the car, depending on driving conditions. EBD works as part of a traditional 4-channel electronically controlled ABS. When stopping a rectilinearly moving car, the load is redistributed. The front wheels are loaded and the rear wheels are not loaded.

ABS - electronic braking system

Therefore, if the rear brakes develop the same force as the front brakes, the chances of the rear wheels locking up will increase. Using wheel speed sensors, the ABS control unit detects this moment and controls the input force. It should be noted that the distribution of forces between the axles during braking significantly depends on the mass of the load and its location. The second situation where electronic intervention becomes useful is when stopping at an angle. In this case, the outer wheels are loaded and the inner wheels are unloaded, so there is a risk of their blocking. Based on the signals from the wheel sensors and the acceleration sensor, the EBD determines the wheel braking conditions. And with the help of a combination of valves, it regulates the pressure of the fluid supplied to each of the wheel mechanisms.

The operation of the electronic brake system

How does ABS work? It should be noted that the maximum adhesion of the wheel to the road surface, be it dry or wet asphalt, wet paver or rolled snow, is achieved with some, or rather 15-30 percent relative slip. It is this slippage that is the only permissible and desirable that is ensured by the adjustment of the elements of the system. What are these elements? First, we note that ABS works by creating pressure pulses of brake fluid that are transmitted to the wheels. All existing ABS vehicles include three main components. Sensors are mounted on wheels and record rotation speed, an electronic data processing device and a modulator or even a modulator, sensors. Imagine that the edge of the gear is attached to the wheel hub. The sensor is mounted above the end of the crown.

What does the electronic brake system of a car consist of?

It consists of a magnetic core located inside the coil. Electric current is induced in the winding when the gear rotates. The frequency of which is directly proportional to the angular velocity of the wheel. Information received in this way from the sensor is transmitted via cable to the electronic control unit. An electronic control unit that receives information called from the wheels controls the device for monitoring the moments of their blocking. And because the blockage is caused by excess pressure of the brake fluid in the line that leads it to the wheel. The brain generates a command to lower the pressure. Modulators Modulators containing, as a rule, two electromagnetic valves, execute this command. The first blocks the access of fluid to the line passing from the main cylinder to the wheel. And the second, with excess pressure, opens the way for brake fluid in the reservoir of the low-pressure battery.

Types of electronic brake system

In the most expensive and, therefore, the most efficient four-channel systems, each wheel has an individual brake fluid pressure control. Naturally, the number of angular velocity sensors, pressure modulators and control channels in this case is equal to the number of wheels. All four-channel systems perform the function of EBD, brake axle adjustment. The cheapest are one common modulator and one control channel. With such ABS, all wheels are disinfected when at least one of them is locked. The most widely used system is with four sensors, but with two modulators and two control channels. They adjust the axle pressure according to the signal of the sensor or the worst wheel. Finally, they launch a three-channel system. Three modulators of this system serve three channels. Now we are moving from theory to practice. Why should you still strive to buy a car with ABS?

The operation of the electronic brake system

In an emergency, when you instinctively press the brake pedal with force, in any, even the most adverse road conditions, the car will not turn, it will not lead you off course. On the contrary, the controllability of the car will remain. This means that you can get around the obstacle, and when you stop on a slippery bend, avoid skating. The operation of the ABS is accompanied by impulsive twitching on the brake pedal. Their strength depends on the specific brand of the car and the sound of rattling sound from the modulator module. System performance is indicated by a light indicator marked “ABS” on the instrument panel. The indicator lights up when the ignition is turned on and turns off after 2-3 seconds after starting the engine. It should be remembered that a car stop with ABS should not be repeated and interrupted.

Electronic brake system

During the braking process, the brake pedal must be pressed with considerable force. The system itself will provide the smallest stopping distance. On dry roads, ABS can reduce the braking distance of a car by about 20% compared to the braking distance of cars with locked wheels. On snow, ice, wet asphalt, the difference, of course, will be much greater. I noticed. The use of ABS helps extend tire life. Installation of ABS does not significantly increase the cost of the car, does not complicate its maintenance and does not require special driving skills from the driver. Continuous improvement of the design of systems along with a reduction in their price will soon lead to the fact that they will become an integral, standard part of cars of all classes. Problems with the operation of the ABS.

Reliability of the electronic brake system

Note that modern ABS has a fairly high reliability and can operate for a long time without failures. Electronic components of the ABS fail extremely rarely. Since they are protected by special relays and fuses, and if such a malfunction still occurs, the reason for this is often due to a violation of the rules and recommendations that will be mentioned below. The most vulnerable in the ABS circuit are wheel sensors. Located next to the rotating parts of the hub or axle. The location of these sensors cannot be called safe. Various impurities or even too much clearance in the hub bearings can cause sensor malfunctions, which most often cause ABS malfunctions. In addition, the voltage between the battery terminals affects the operation of the ABS.

Electronic brake voltage

If the voltage drops to 10,5 V and lower, the ABS can be disabled independently via the electronic safety unit. The protective relay can also be turned off if there are unacceptable fluctuations and surges in the vehicle network. To avoid this, it is impossible to turn off the electrical collectors with the ignition on and the engine running. It is necessary to strictly monitor the state of the generator contact connections. If you need to start the engine by starting it from an external battery or securing your car. As a donor for this purpose, observe the following rules. When you connect the wires from an external battery so that the ignition of your car is turned off, the key is removed from the lock. Allow the battery to charge for 5-10 minutes. The fact that the ABS is faulty is indicated by a warning lamp on the instrument panel.

Checking the electronic brake system

Do not react too nervously to this, the car will not be left without brakes, but when stopped, it will behave like a car in which there is no ABS. If the ABS indicator lights up while driving, stop the car, turn off the engine and check the voltage between the battery terminals. If it falls below 10,5 V, you can continue to move and charge the battery as soon as possible. If the ABS indicator periodically lights up and goes out, then most likely some contact in the ABS circuit is blocked. The car must have entered the inspection ditch, all wires are checked, and the electrical contacts are stripped. If the cause of the flashing ABS lamp is not detected. There are a number of functions related to the maintenance or repair of the ABS brake system.

Questions and answers:

What is an auxiliary braking system? This is a system that is able to maintain a certain speed of the car. It is used for driving on long slopes, and works by turning off the fuel supply to the cylinders (brake by the motor).

What is a spare emergency braking system? This system provides adequate braking if the main braking system fails. It also triggers if the efficiency of the main vehicle decreases.

What kind of braking system is there? The car uses a service brake system (main), parking (hand brake) and auxiliary or emergency (for emergency cases, when the main vehicle does not work).

What braking system is used to hold a stopped vehicle? The parking brake system is used to keep the vehicle at a standstill independently in its place, for example, when parking down a hill.