ABS (automatic anti-lock braking system) can be said to be the three most important inventions in the history of safety (the other two are airbags and seat belts), ABS is also other safety devices (such as the basis of the dynamic stability system ESP flow with EBD braking force distribution system). This year marks the 25th anniversary of the birth of the ABS system. Over the past 25 years, ABS systems have saved nearly 15,000 precious lives of North American drivers. Let us take this opportunity to review the development and impact of ABS systems and the impact it has brought to the automotive industry
2004 was the first The 25th anniversary of the birth of the first mass-produced civilian ABS (anti-lock braking system, automatic anti-lock braking system). Over the past quarter of a century, ABS systems have not only continued to improve and strive for excellence, but have also caused many owners to escape through the gates of hell. In addition to introducing the ABS system that has made great contributions in the past 25 years, we need to review the history of ABS. The principle of "automatic anti-lock braking"
It is not difficult to understand that in an emergency, if the ABS system is not installed on the vehicle, it will only slow down and immediately step on the brakes before it is too late. Due to the inertia of the vehicle dashboard, sliding can occur instantaneously, causing the driving direction and body movement trajectory to deviate in an uncontrolled and dangerous situation! When the locked wheels are about to reach a critical point in a vehicle equipped with an ABS system, the brakes can be applied 60 to 120 times a second, equivalent to holding the brakes and relaxing, i.e. similar to the "pumping" effect of mechanical automation. This avoids emergency braking, wheel slip control, and increases tire friction, making braking efficiency over 90%.
From microscopic analysis, when the tire is rolled into a critical point between the tire and the maximum sliding friction. Start to give full play to the engine's power output in the car (shorten the acceleration time), and maximize the braking effect if you decelerate (the braking distance is the shortest). The ABS hydraulic unit control system controller uses brake pressure to repeatedly swing the tire to the critical point of slippage, so that during repeated contact, the grip closest to the tire is removed while maintaining the maximum theoretical value to achieve optimal braking. Effective braking.
Operation
The principle of ABS seems simple, but it has experienced many setbacks in the process of starting from scratch (lack of key technologies)! In 1908, British engineer JE Francis proposed the theory of "wheel-holding sliding controller for railway vehicles", but it was not practical. In the next 30 years, attempts including Carl Wessel's "brake force controller", Werner MHL's "hydraulic brake safety device" and Richard Trapp's "wheel locking" all failed. The "Automotive Technical Manual" published in 1941 wrote: "Until now, any attempt by mechanical devices to prevent the danger of wheel lock has been unsuccessful. This day is an important milestone in the history of successful traffic safety equipment. ," Unfortunately, the author of this book probably didn't expect me to have to wait 30 years for this day.
What is the bottleneck in the development of anti-lock braking system technology? First of all, it is necessary to monitor the tire speed change system device in real time and adjust the size of the brake hydraulic system immediately. In the era without integrated computers, no mechanical device is needed to achieve such a rapid response! It was not until the birth of the ABS system in the early 1960s that a glimmer of hope was revealed, and there was already preliminary scale semiconductor technology.
The history of the ABS system developed by Germany's Bosch (BOSCH), a company specializing in automotive electronic systems, can be traced back to 1936, when Bosch applied for a patent for "motor vehicle braking system, anti-locking device". In 1964 (also the year of the birth of integrated circuits) Bosch ABS Company's research and development plan was restarted, and finally came to the conclusion that "it is feasible to control the wheels through electronic devices to prevent wheel locking". This is ABS (anti-lock braking system) ) noun appeared for the first time in history! The world's first prototype using ABS appeared in 1966, which showed that "shortening the braking distance" is not an impossible task. Due to excessive capital investment, applications are limited to initial ABS rail vehicles or aircraft. The company Teldix GmbH co-developed the first Mercedes-Benz prototype for a road vehicle in 1970 - ABS 1. The system already had a production base, but the control elements within the unit lacked reliability, and more than 1000, not only is the cost high, but it is also prone to failure.
In 1973, Bosch purchased 50% of the shares and acquired the ABS developed by Teldix Co., Ltd. In 1975, AEG entered into an agreement with Bosch Teldix, and the ABS system developed by Bosch was planned to be completely Delegate execution. After three years of hard work "ABS 2" was born! Unlike ABS 1 analog electronics, the ABS 2 system is fully digital and the components are designed not only to control the number of component units dropped from 1000 to 140, but also to have lower cost, reliability and operating speed significantly increased significantly over Acceleration 3 Main advantage. At the end of 1978 the two German car manufacturers Mercedes-Benz and BMW decided to equip the S-Class 2 and 7 Series sedans with high-tech ABS systems.
In the three years before its birth, the ABS system was too costly and did not suffer from market development. From 1978 to the end of 1980, Bosch sold only 24,000 ABS systems in total. Fortunately, growth came the following year to 76,000 units. Through positive market response, Bosch started a TCS traction control system research and development plan. The ABS 2S system introduced in 1983 reduced weight to 4.3 kg to 5.5 kg, and the control module was also reduced to 70. By mid-1985, for the first time, the proportion of ABS systems installed in new car plants in the world exceeded 1%, and General Motors also decided to make its main ABS standard equipment on Chevrolet vehicles.
1986 was another memorable year, in addition to celebrating Bosch selling one million ABS systems, more importantly Bosch launched the first ever automotive TCS with civilian/ASR traction control system. The function of TCS/ASR is to prevent the wheels from slipping during vehicle acceleration, especially to prevent wheels from spinning when cornering. The slip is controlled within the range of 10% to 20%. Since ASR is controlled by adjusting the torque of the driving wheels, the drive force control system is also known as TRC or TRAC in Japan.
ASR and ABS work in many similar areas, and the two are combined to form a better effect and form the wheel with anti-wheel lock and anti-skid control (ABS/ASR) system. The system consists of wheel speed sensor, ABS/ASR ECU controller, ABS driver, ASR driver, controller, auxiliary throttle's main and auxiliary throttle position sensors, etc. During the process of starting, accelerating, and moving the car, based on the input signal of the wheel speed sensor, when the judgment of the driving wheel slip exceeds the upper limit, the engine ECU then enters the air defense program in sequence. The first pair is used by the engine ECU to reduce the throttle to reduce the engine torque when entering fuel and reduce the power output. When the ECU determines that intervention on the driving wheels is required, a signal is transmitted to the control of the ASR of the driving wheels (usually the front wheels) to prevent the driving wheels from slipping, or maintain it within a safe range. The first new model equipped with an ASR system appeared in 1987, and the Mercedes-Benz S-Class once again made history.
As the price of ABS systems decreases and the number of new cars equipped with ABS systems reaches a critical point in 1988, it reaches an explosive growth and begins to grow rapidly. Bosch's annual sales of ABS systems have exceeded for the first time this year. 3 million sets. A technological breakthrough that led Bosch to launch the first ABS 2E system in 1989 was originally isolated from the engine compartment (hydraulic drive assembly) and console (electronic control unit), and the wiring had to rely on complex design changes to "integrate these two" The component is "Design!" The ABS 2E system also wrote a new milestone once again by discarding and replacing the first integrated circuit in history responsible for all the work of the ABS control system with an 8 K-byte computing microprocessor (CPU). The car manufacturer officially announced that a Porsche car had ABS installed, and three years later (1992) Mercedes-Benz Porsche also decided to keep up with the times.
Half of the 1990s ABS systems gradually became popular in production cars.
The improved version of Bosch ABS 2E was launched in 1993: the ABS 5.0 system. In addition to being smaller and lighter, the ABS 5.0 unit has twice the computing speed (16 Kbytes) of the processor. The company also celebrates the 10 millionth unit sold every year. ABS system of the same year.
ABS and ASR/TCS systems have been recognized around the world as owners, but Bosch’s engineering team is not satisfied and has set its sights on a more challenging goal: ESP (Electronic Stability Program, Driving Dynamic Stability System) Go ahead! Unlike ABS and TCS which can only increase stability during braking and acceleration, ESP can maintain dynamic balance of the vehicle at all times during driving with the optimal route. The ESP system includes a steering sensor (monitors the steering wheel angle to determine that the vehicle is traveling in the correct direction), a wheel sensor (monitors each wheel to determine the speed of the wheel slip), a yaw rate sensor (around the vertical axis when capturing dynamic car movements), and (to determine whether a car is out of control) and the lateral acceleration sensor (the centrifugal acceleration measured when turning to determine whether the vehicle has lost grip when turning). At the same time, the data from these sensors are used to determine the vehicle driving state of the control unit, thereby indicating Brake pressure to one or more wheels is built or released at the same time as the engine's torque is adjusted for the most accurate response, in some cases even 150 times per second. Integrated ABS, EBD, EDL, ASR systems, such as ESP, allow car owners to focus on driving and allow the computer to easily cope with various emergencies.
Continuing with the birth practices of ABS and ASR in the past, the Mercedes-Benz S-Class was the first model to use an ESP system (1995). Four years later, Mercedes-Benz officially announced that all car series will be equipped with ESP as standard equipment. At the same time, Bosch launched ABS 5.7 in 1998 and 2001, the ABS 8.0 system is still better, the total system weight has been upgraded from 2.5 kg to 1.6 kg, and the processor has been upgraded from 48 KB to 128 KB In 2001, all cars of Mercedes-Benz's main competitors, BMW and Audi, also announced that they would be equipped with ESP as standard configuration. Bosch celebrates the car manufacturer's sales of more than 10,000 and 100,000 ABS ESP systems in 2003. According to a survey by ACEA (European Automobile Manufacturers Association), today every new car equipped with an ABS system is produced across the European continent. More than 60% of all new cars in the world have this device.
“ABS braking systems greatly improve stability and shorten braking distances,” said Wolfgang Dries, member of the board of directors of Robert Bosch GmbH (Bosch’s full name). Unlike airbags and seat belts (the ratio of the number of car accidents is divisible by the number of deaths), is it more difficult to snatch many people back from the door of ABS system "prevention" hell? However, according to a study by the German Insurance Association, which analyzes serious injuries caused by safety cars after accidents, it is shown that 60%, 30% and 40% of fatalities due to side traffic accidents caused by crashes are due to speeding, sudden steering or improper operation. of. We have reason to believe that ABS, ASR and ESP systems result in a significant reduction in the incidence of emergency vehicle loss of control. The National Highway Traffic Safety Administration (NHTSA) estimates that ABS systems have saved 14,563 motorists living in North America!
From ABS to ESP, automotive engineers seem to have reached their limit in their efforts to improve driving stability (civilian ESP systems have been in existence for nearly 10 years), but even the most advanced computers still require proper driver operation achieve maximum results. At the end of the article, we will show you how to use the ABS system?
Most homeowners have never faced an emergency (I hope never), but don’t know how to deal with a critical moment? When braking in an emergency situation, for a fast-moving ABS brake cylinder system, the brake pedal is significantly and abnormally vibrating and making noise (normal phenomenon in the operation of the ABS system), then you should not hesitate to force the brakes (unless the The vehicle has an EBD braking force assist device (otherwise the braking force is not enough for most drivers), and ABS prevents the wheels from locking during emergency braking, so the direction of the front wheels can still be controlled by the mechanism.
The driver should brake sideways while playing with the direction to avoid danger and avoid road obstacles to the left. For example, he should depress the brake pedal vigorously, quickly turn the steering wheel 90 degrees left and right, turn the wheel 180 degrees, and finally return to the left 90 degrees. Spend. The last thing to mention is that the ABS system relies on sophisticated wheel speed sensors to determine whether a locking situation has occurred? Each wheel sensor must generally be kept clean to prevent dirt, oil, and especially magnet material from adhering to the surface, which may cause the sensor to fail or input an erroneous signal and affect the normal operation of the ABS system. Before driving, you should always pay attention to whether the ABS fault indicator light on the dashboard is flashing or long. The ABS system may have failed (especially the early system), and the repair shop should eliminate the fault as soon as possible.
Finally, I would like to remind readers that ABS/ASR/ESP systems are not a panacea for speeding traffic, but because these active safety systems are the crystallization of high-tech technology, they should not be used against speeding traffic. ABS has indeed saved the lives of many drivers in the past, but it cannot guarantee that every driver will be saved from danger, right?
There is some information about ABS, which is shared as follows:
Currently, the latest ABS has developed to the fifth generation (some say it is the eighth generation, I don’t know the truth) False), today's ABS still derives other electronic control systems, such as:
1. Electronic Traction System (ETC).
2. Electronic Stability Program (ESP)
3. Brake Assist (BA)
(Note: All manufacturers have different naming systems, but the principle are the same, but most of the ESP system categories are from Bosch)
Except ABS:
In terms of mechanical and electronic classification, the differences between the two are as follows:
1. Electronic ABS is designed according to different car models. Its installation requires professional skills and can be transferred to another vehicle. If its circuit design and battery capacity must be changed, there is no universality; mechanical ABS is universal. It's so durable that you can swap it from one vehicle to another as long as the vehicle's hydraulic brake system is operational, and it only takes 30 minutes to install.
2. There is a large amount of electronic ABS, and the finished product may not have enough space for installing electronic ABS on the car. In contrast, the small size of mechanical ABS takes up less space.
3. The electronic ABS starts working at the moment the wheel lock is activated, 612 times per second; the mechanical ABS starts working at the moment of braking, and works 60% the second time depending on the speed. -120. Higher
4. The cost of electronic ABS is more economical than mechanical ABS.
According to the classification of control channels, there are the following types:
Four channels, function: using high adhesion coefficient, it can maximize the maximum adhesion of each wheel braking. However, if the coefficients of the two wheels attached to the left and right of the car have a large difference (such as water or icy road sections), it will affect the stability of the car's braking direction. Guangzhou Honda uses a four-channel ABS system.
Three-channel type, features: good directional stability under various conditions when braking with a vehicle. Three-channel ABS is widely used in automobiles.
Dual-channel function: Dual-channel ABS is difficult to control in all aspects of directional stability, steering and braking performance, and is currently rarely used
One channel type, features: With simple structure and low cost, light truck vehicles are suitable for a wide range of applications.
Basic components of anti-lock braking system:
ABS wheel speed sensor usually includes brake pressure adjustment device, electronic control unit and ABS warning light, which are composed of different ABS systems The structure and working principle of the brake pressure regulating device are usually different, and the internal structure of the electronic control unit and control logic circuit can also vary.
The varieties of ABS are the same in the following aspects:
(1) ABS for cars exceeding a certain speed (such as 5 kilometers per hour or 8 km/h) only after the anti-lock brake pressure is adjusted during braking, the wheel lock will often be adjusted.
(2) When braking, control is performed. Only when the wheel has a tendency to lock, the ABS tends to adjust the anti-lock brake pressure to lock the wheel; the wheel is not locked after the wheel locking effect is controlled, The braking process of the system is exactly the same as that of conventional braking
(3) ABS has a self-diagnostic function and can be monitored by the working system. Once it is found that it affects the normal operation of the system, it will automatically shut down. When ABS malfunctions and the ABS warning light signals to alert the driver, the car's braking system can still brake like a conventional braking system.
ABS use characteristics:
1. The brake pedal should be a pedal for the low friction coefficient on the road during braking.
2. It can be used in the shortest time The braking distance of the parking lot
3. When the car brakes with high directional stability