in the past, when consumers bought a car, the presence or absence of ABS was regarded as an important indicator. With the development of technology, at present, most cars in China have adopted ABS as standard configuration. However, many drivers are not very clear about the understanding of ABS and how to use it correctly, and even have some misunderstandings about ABS. Some drivers think that ABS is a device to shorten the braking distance. The braking distance of vehicles equipped with ABS on any road surface must be shorter than that without ABS. Some people even mistakenly think that the braking distance on ice and snow roads can be equivalent to that on asphalt roads. There are also some drivers who believe that as long as ABS is equipped, even if driving at high speed on rainy days or ice and snow roads, there will be no vehicle out of control. ABS does not greatly improve the limit of automobile physical properties as some people think. Strictly speaking, the function of ABS is mainly within the physical limit performance, ensuring the maneuverability and stability of the vehicle itself when braking. At the same time, when accelerating, it can also prevent the pure slip of the tire and improve the acceleration performance and operational stability.
[ Edit this paragraph] Application of ABS
The full name of ABS is Anti-lock Brake System or Anti-skid Braking System, which can effectively control the wheels to keep in rotation, improve the stability of the vehicle during braking and the braking performance of the vehicle under poor road conditions. ABS constantly detects the rotation speed of each wheel through the rotation speed sensors installed on each wheel or transmission shaft, and the computer calculates the wheel slip rate at that time, and compares it with the ideal slip rate, so as to make a decision to increase or decrease the braking pressure of the brake and order the actuator to adjust the braking pressure in time to keep the wheel in an ideal braking state.
ABS was patented for the first time in p>196. In 1936, Bosch registered a "mechanical" patent to prevent motor vehicle wheels from locking. All the early designs have the same problem: they are too complicated and easy to fail, and they operate too slowly. In 1947, the world's first ABS system was first applied to the B-47 bomber. Teldix began to study this project in 1964, and its ABS research was quickly taken over by Bosch. Within two years, the first batch of ABS test vehicles have the function of shortening the braking distance. The steering and stability of the vehicle are also guaranteed when turning, but about 1 analog components and safety switches were used at that time, which means that the reliability and durability of the electronic control unit called ABS 1 system can not meet the requirements of mass production and needs to be improved. The technology acquired by Bosch in the development of electronic engine management, the arrival of digital technology and integrated circuit (ICs) reduced the number of electronic components to 14.
in p>1968, ABS began to be applied to automobiles. In 1975, many heavy trucks and buses were equipped with ABS due to the adoption of the 121 section of the federal motor vehicle safety standard in the United States. However, due to many technical problems in the braking system and the opposition of the truck industry, this standard was revoked in 1978. In the same year, Bosch, as the first company in the world to launch an ABS system with electronic control function, began to install this ABS 2 system as an optional configuration, and assembled it on a Mercedes-Benz S-class car, and then quickly installed it on a BMW 7 series luxury car. After this period, the further research and design of ABS in the United States decreased, but the manufacturers in Europe and Japan continued to carefully develop ABS.
since 198s, American automobile manufacturers have shown new interest in ABS in the American automobile market because the cars imported from America are equipped with ABS. With the rapid development of microelectronics technology and people's strong demand for automobile driving safety, ABS devices are further widely used in the world automobile industry. In 1987, about 3% cars in the United States were equipped with very reliable ABS. In the following time, developers focused on simplifying the system. In 1989, Bosch engineers successfully attached a hybrid control unit directly to the hydraulic module. In this way, they don't need wiring harness connecting the control unit and the hydraulic module, and they don't need connectors, so the overall weight of ABS 2E is significantly reduced.
in 1993, Bosch engineers created ABS 5. with new solenoid valves, and developed versions 5.3 and 5.7 in the following years. The main features of the new generation ABS 8 are to greatly reduce the weight, reduce the volume, increase the memory, and add more functions, such as electronic distribution of brake pressure, thus replacing the mechanical mechanism to reduce the brake pressure of the rear axle. At that time, the prediction of some automobile industry analysts was confirmed: after the mid-199s, most cars and trucks in the world market will be equipped with ABS.
[ Edit this paragraph] Function of ABS
The main function of ABS is to improve the braking performance of the whole vehicle, improve driving safety, and prevent the wheels from locking (that is, stop rolling) during braking, so as to ensure that the driver can still control the direction when braking and prevent the rear axle from slipping. Its working principle is: in case of emergency braking, once a wheel is found to be locked, the computer immediately controls the pressure regulator to release the pressure from the brake cylinder of the wheel, so that the wheel can resume rotation and the purpose of preventing the wheel from being locked is achieved. The working process of ABS is actually a cyclic working process of "locking-releasing-locking-releasing", which makes the vehicle always in a critical locking gap rolling state, effectively overcomes the vehicle deviation caused by wheel locking during emergency braking, and prevents the occurrence of out-of-control situations.
ABS can be divided into mechanical and electronic types. Mechanical ABS has a simple structure, and the braking force can be simply adjusted mainly by using its own internal structure. The working principle of the device is simple, there is no sensor to feed back signals such as road friction and wheel speed, and it works entirely by preset data. No matter whether it is a waterlogged road surface, an icy road surface or a muddy road surface or a good cement asphalt road surface, its working mode is the same. Strictly speaking, this kind of ABS can only be called "Advanced Brake System". At present, only some low-end pickup trucks and other models in China still use mechanical ABS.
mechanical ABS only uses the physical characteristics of components to remove mechanical actions, while electronic ABS uses computers to analyze and calculate various data to get results. Electronic ABS consists of wheel speed sensor, wire harness, computer, ABS hydraulic pump, indicator light and other components. According to the signal of the wheel speed sensor of each wheel, the computer can apply different braking force to each wheel, so as to achieve the effect of scientific and reasonable distribution of braking force.
the earliest ABS system was a two-wheel system. The so-called two-wheel system is to install ABS on the two rear wheels of the car. Because the two rear wheels share a brake hydraulic pipeline and a control valve, it is also called "single channel control system". This system selects the braking pressure according to the state of the wheel with less adhesion among the two rear wheels, which is called the "low selection principle". That is to say, when one rear wheel of ABS vehicle adopts the principle of low selection tends to lock up, the system can only release pressure to both rear wheels at the same time. Because the front wheel has no anti-lock function, it is difficult for the two-wheel system to achieve the best braking effect.
with the development of related technologies, a "three-channel control system" appeared later. Based on the two-wheel system, the two front wheels are independently controlled by two separate pipelines. Although the rear wheel still adopts the principle of "low selection", this system has the main characteristics of modern ABS because it realizes the steering function during emergency braking and the function of preventing the rear axle from slipping. Up to now, there are still vehicles on the market using this three-channel control ABS system.
at present, the four-sensor four-channel ABS system is the most common equipment on vehicles, and each wheel is controlled by an independent hydraulic pipeline and solenoid valve, which can realize independent control of a single wheel. This structure can achieve good anti-lock function.
[ Edit this paragraph] Get out of the misunderstanding of ABS
Those misunderstandings about ABS in the opening paragraph need to be explained. If the wheels of a car are locked when braking, the lateral adhesion that the car can get is the smallest. At this time, due to the imbalance of road adhesion coefficient, automobile braking force, suspension imbalance, automobile tire pressure, road curvature, bumps or slopes, and other factors, the automobile may slip, tail flick or get out of control. In addition, because the front wheel of the vehicle is locked, the car will lose its steering ability. An anti-lock braking system with excellent performance can control the slip rate of automobile wheels between 2% and 3% when braking. In this state, the wheels can give consideration to the relative maximum longitudinal braking force and lateral grip, effectively ensuring that the vehicle will not get out of control. In addition, under the condition that the front wheels are not locked, because of a certain grip, the car can also turn according to the driver's wishes, thus controlling the vehicle. In order to control the wheel slip rate in an ideal state and pursue the stability of the vehicle, some longitudinal braking force may be sacrificed. Therefore, when ABS works, the braking distance will not be shortened on all roads.
On the ice and snow pavement, the adhesion provided by the ground is much smaller than that provided by ordinary pavement. ABS can only adjust the braking force of the car on the basis of this adhesion, and will not produce additional braking factors. Therefore, the braking distance on the ice and snow road can only be said to be shorter than when the wheel is locked, and it is still much longer than on the general road.
The actual road is actually very complicated, such as the unbalanced adhesion coefficient of the road surface, the road curvature or the lateral slope of the road surface, and even the tire pressure of the car. There are many factors that can make the car slip when braking, and these factors are not overcome by ABS itself. Therefore, if the vehicle brakes suddenly when the speed is too fast on the ice and snow road, when one of the above factors is encountered, when the centrifugal force of the vehicle is greater than the maximum lateral force that can be provided by the ground, the vehicle will become out of control, which is very dangerous.
In short, no equipment can do everything, and drivers must achieve safe driving through their own subjective initiative. Even the ABS with excellent performance has limited effect on stabilizing vehicles under working conditions, especially when driving on gravel roads or ice and snow roads, you should keep sufficient distance between vehicles, slow down and do not rely entirely on ABS system.
[ Edit this paragraph] Common knowledge of ABS use
Now basically all passenger cars are equipped with ABS system, which plays a great role in improving the active safety performance of vehicles, but if it is used improperly, the effect will be greatly reduced. Here, our principle of using ABS is summarized as "four musts and seven don 'ts".
Four Essentials
1. Always keep on the brake pedal, so as to ensure sufficient and continuous braking force and make ABS work effectively.
2. Keep enough safety distance. Under normal circumstances, the minimum vehicle distance should not be less than 5m. When the vehicle speed exceeds 5km/h, the minimum vehicle distance is the same as the vehicle speed. For example, the minimum vehicle distance is 1m at 1km/h and 12m at 12km/h..
3. Be familiar with ABS in advance, so that you can prepare and adapt to the brake pedal jitter when ABS works.
4. read the driver's manual in advance, so as to further understand the various operating instructions provided by the automobile manufacturer where ABS is installed.
seven don't
1. Don't think that you can drive as you like with ABS. ABS is not absolutely safe either. If the vehicle brakes too hard and too fast, it will still slip. Therefore, even if your car is equipped with ABS, you still need to drive carefully.
2. Don't use "point brake" for braking. When vehicles without ABS are braked on wet roads and at high speed, it is necessary to use the method of "point braking" to achieve the purpose of safe braking. After installing ABS, because ABS can automatically adjust the braking force, when implementing emergency braking, you can step on the pedal to the end without releasing it, so don't worry about the wheel locking and slipping, otherwise the braking distance will be greatly extended.
3. Don't be frightened by the jitter of ABS. When ABS works, it will hear the noise it makes, which is generated by the solenoid valve and hydraulic pump in the hydraulic control system. Don't panic because there is something wrong with the brake system, and don't move your feet away from the brake pedal. At this time, you still have to trample the brake pedal to death and leave it alone.
4. Do not ignore the inspection of ABS indicator light. Under normal circumstances, after the ignition switch is turned on, this light should be on; It goes out automatically after about 3 seconds. In this process, in essence, the electronic control device is conducting power-on inspection on the wheel sensor and the control valve of the hydraulic regulator according to the self-inspection procedure. If this light is not lit all the time, it means that the ABS is faulty.
5. don't panic when the ABS indicator light is on. When the ABS fails during driving, the anti-lock braking system automatically connects the oil circuit of the original braking system, and the original braking system on the car still works, but without ABS, it is enough to pay attention to maintenance.
6. Do not disassemble and replace the computer unit of ABS without permission. If the computer finds a fault, the whole ABS unit should be replaced.
7. For vehicles equipped with ABS, but want to be modified, please do not disassemble the nuts connecting the brake pipe and ABS unit.
ABS is divided into electronic ABS and mechanical ABS
1. Electronic ABS is designed according to different models, and its installation requires professional technical force. If it is changed to another car, it must change its circuit design and battery capacity, which is not universal; The mechanical ABS is versatile, and can be used by any vehicle with hydraulic braking device, and can be changed from one vehicle to another, and the installation takes only 3 minutes.
2. Electronic ABS is bulky, but the finished car may not have enough space to install electronic ABS. In contrast, mechanical ABS is smaller and takes up less space.
3. Electronic ABS starts to work at the moment when the wheel is locked, and it works for 6~12 times per second; Mechanical ABS starts to work when braking, and it can act 6~12 times per second according to different vehicle speeds.
The applicable characteristics of mechanical ABS need to be set in advance. On the roads with accumulated water, ice and snow, sand and stone, and asphalt, the friction coefficient of tires is different, and the braking force required is different with different vehicle speeds. There is no real-time measurement feedback system, only relying on the preset terbium value, the application range is narrow, and the braking effect will be reduced.
you should be very careful when purchasing mechanical ABS anti-lock braking system. Fake ABS products are similar to the real ones in appearance.