What's the secret? A detailed explanation of the ESP electronic stability system

The Electronic Stability Program (ESP) is actually a comprehensive strategy for vehicle body stability control, which includes the Anti-lock Braking System (ABS) and the Anti-skid System (ASR). It can be said that it is a functional extension of other active and passive safety systems, rather than an independent configuration. So, what is the secret behind the ESP system that is now equipped on many models? Next, we will analyze it in detail for you.

In order to illustrate the secrets hidden in the ESP system in a vivid and specific way, we will use the ESP systems on the Sagitar and Magotan as examples. The ESP systems on these two models include nine detailed functions, namely: ABS (anti-deadlock braking system), EBD (electronic brake force distribution system), ESBS (extended electronic stability braking system), HVV (rear axle full deceleration), ASR (traction control system), EDL (electronic differential lock), MASR (engine drag torque control), HBA (hydraulic auxiliary braking) and LDE (low-power ESP). Next, let's take a look at the above functions and what role they will play in daily driving. (Note: The ESP systems on these two models are not provided by Bosch (BOSH). The Magotan is provided by TRW of the United States, while the Sagitar is provided by Continental Teves of Germany.)

ABS (Anti-lock Braking System)

ABS is often mentioned in daily life, and its full English name is "Anti-lock Break System", and its Chinese name is "Anti-lock Braking System". This system can brake continuously 60 to 120 times in one second when the wheels are about to lock under braking, which is somewhat similar to mechanical "point braking". This can effectively avoid loss of control or wheel side slip during emergency braking. At the same time, because the wheels will not be locked during braking, the tires will not rub against the ground at one point, thus increasing the friction and making the braking efficiency reach more than 90%.

ABS anti-lock braking system is divided into mechanical and electronic types. Mechanical ABS has a simple structure and mainly uses its own internal structure to achieve the effect of simple adjustment of braking force. There is no sensor to feedback signals such as road friction and wheel speed. It relies entirely on pre-set data to work. Therefore, its working method is the same under any road conditions. At present, only some low-end pickup trucks and other models in China are still using mechanical ABS. Electronic ABS is composed of hydraulic braking system, wheel speed sensor, electronic controller and electromagnetic regulator. Its working principle is that the wheel speed sensor monitors the speed of the wheel, and the monitoring signal is collected and analyzed in the electronic controller. Once it is detected that the wheel is about to lock, the electronic controller will send a command to the electromagnetic regulator, which controls the oil pressure distribution valve to adjust the brake cylinder of each wheel, and controls the brake friction pad in a "one release and one retraction" point release form to release the wheel and release the wheel lock phenomenon.

EBD (Electronic Brake Force Distribution)

EBD, also known as EBFD, stands for "Electrontc Brake-Force Distribution:", which is translated into Chinese as "Electronic Brake Force Distribution System". This system is an electronic active safety system that can dynamically distribute braking force to the four wheels according to vehicle conditions, road conditions and braking status. This system is actually an auxiliary function of ABS.

The working principle of the EBD system is as follows:

1. The driver presses the brake pedal and EBD starts working.

2. The vehicle mass sensor calculates the vehicle mass and submits it to the ECU.

3. The wheel sensor collects the current four-wheel speed, friction and other information and transmits it to the ECU.

4. After receiving the data, the ECU calculates how much braking pressure should be allocated to each wheel through the calculation module.

5. The brake force distributor is activated, notifying ABS to stand by.

6. Activate the ABS system when necessary.

7. Braking begins.

To put it simply, when the car brakes, if the conditions under which the four tires adhere to the ground are different, for example, the left wheel adheres to a wet road and the right wheel adheres to a dry road, then the friction between the four wheels and the ground will be different. When braking (the braking force of the four wheels is the same), it is easy to slip, tilt, and roll over. The EBD system will adjust the braking pressure of each tire in time at this time to ensure that the vehicle can decelerate effectively and smoothly.

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ESBS (Extended Electronic Stability Braking System)

The full name of ESBS in English is “Erweitertes-Stabilitts-Brems-System”, which means “Extended Electronic Stability Braking System”. This system is also another auxiliary function of ABS. It increases the stability of the vehicle while reducing the risk of skidding. It can effectively avoid serious accidents by stabilizing the vehicle and preventing skidding in emergency situations.

HVV (rear axle full reduction)

The full name of HVV is "Hinterachs-Voll-Verzgerung" - full rear axle deceleration. When the front wheels of the vehicle enter the ABS state but the rear wheels have not started to move, the system will increase the brake oil pressure of the rear wheels, so that the rear wheels will also enter the ABS state, thereby providing rapid braking performance and effectively shortening the braking distance.

ASR (Anti-Slip System)

I believe that some friends who are usually interested in vehicles will be familiar with ASR. It is "Antriebs-Schlupf-Regelung" - the Chinese name is drive anti-skid system, which is an active safety device, also known as traction control system. It can effectively prevent the car's drive wheels from slipping when accelerating, especially on special roads with low friction such as rain, snow, hail, and frozen roads.

The ASR system is actually an upgraded version of ABS. It is equipped with an expandable hydraulic device, a booster pump, a hydraulic pressure cylinder, a fourth wheel speed sensor, a complex electronic system and an electronic acceleration system with its own controller. When the drive wheel slips, the ASR compares the wheel speeds, and the electronic system determines whether the drive wheel is slipping. It immediately automatically reduces the throttle air intake, reduces the engine speed, and thus reduces the power output, and brakes the slipping drive wheel. This can reduce slippage and maintain the most appropriate power output between the tire and the ground grip. At this time, no matter how much gas is added, the drive wheel will not slip under the intervention of ASR.

EDL (Electronic Differential Lock)

EDL is the full spelling of "Elektronische-Differential-Sperre", which means electronic differential lock. It is also an extended function of ABS, used to identify whether the wheels have lost friction with the ground, so as to control the acceleration and slip of the car. When the electronic control unit determines that the driving wheel on one side is slipping, the system brakes the wheel with appropriate intensity through the hydraulic control unit, thereby improving the adhesion utilization rate of the driving wheel on the other side to improve the vehicle's passing ability.

MASR (engine drag torque control)

MASR is the drive anti-skid system. The function of this electronic safety system is very similar to TCS (traction control system). It is currently mainly used in Volkswagen models and is also an extension of ABS. Its function is to identify the slip rate with the help of ABS sensors and automatically reduce the engine resistance torque with the help of the vehicle data bus to achieve the purpose of reducing the slip rate and thus ensure the driving stability of the vehicle. In addition, when the vehicle starts or accelerates on a road with poor adhesion conditions, the MASR system can automatically reduce the engine torque to prevent the drive wheels from slipping so that the vehicle can start smoothly.

HBA (Hydraulic Brake Assist)

"Hydraulischer-Brems-Assistant" - HBA, that is, hydraulic brake assist. This system increases the brake pressure in emergency stops and provides additional pressure when the driver steps on the brake pedal. This means that when the driver quickly steps on the brake pedal, the system will immediately increase the braking force to the maximum level until the ABS system intervenes to prevent the wheels from locking. When the brake pedal is released, the hydraulic brake assist system will be turned off, and if the anti-lock braking system fails, the system will lose its effectiveness and no longer work.

Summary: From the perspective of efficacy, these nine functions can be divided into three categories: ABS, EBV, and ESBS are mainly used to prevent wheel lock; MASR, EDL, and ASR are mainly used to prevent driving slip; and HVV, EDL, and LDE are, in a sense, called the "luxury configuration" of ESP, because in the electronic stability system of most current models, these three functions are still rare. Compared with all models currently sold in the domestic market, not all are equipped with the latest version of the ESP system mentioned above. Therefore, when we usually buy a vehicle, we should not only pay attention to whether the vehicle is equipped with an ESP system, but also further understand whether the ESP system function it matches is powerful enough.

In addition to the functional differences, different versions of ESP systems also have several differences in other aspects. For example, Bosch ESP systems 8.0 and 8.1, the ESP system 8.1 has faster ABS and EBD than the lower version, and the braking distance is shorter, so it can more effectively ensure the braking safety of the vehicle at high speeds. In addition, the 8.1 version of ABS is not only 30% smaller than the 8.0 version, but also 25% lighter, and the layout and performance of the vehicle are further optimized. At the same time, all the electronic wiring harnesses of the 8.1 version of ABS are hidden in the aluminum housing, making its performance more stable and its service life longer. In addition, the higher version of the ESP system has a faster computing speed (CPU from 8K-16K-48K or even higher 128K), and the braking frequency has also changed from automatic braking from several times per second, more than ten times, more than twenty times, and now up to 150 times per second. Therefore, the main difference between different versions of ESP systems is that the effect is more optimized (perfect), the stability is stronger, and the safety protection of the vehicle is more comprehensive, but due to cost constraints, its price is also relatively high.