In the past, when consumers bought a car, whether there was an ABS (anti-lock braking system) was 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.
application of ABS
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ABS (anti-lock brake system), that is, "anti-lock braking system", can effectively control the wheels to keep rotating, and 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.
Function of ABS
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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.