The full name of anti-lock braking system ABS is anti-lock braking system, which can be installed on any car with hydraulic braking. It uses a rubber airbag in the valve body to apply brake oil pressure to the valve body of ABS when braking. At this time, the airbag uses the middle air interlayer to back pressure, so that the wheel can avoid the dead point.
ABS (Anti-lock Braking System) The anti-lock braking system sends a signal that the wheel will be locked through the sensor installed on the wheel, and the controller instructs the regulator to reduce the oil pressure of the wheel brake cylinder and reduce the braking torque. After a certain period of time, the original oil pressure will be restored, and this cycle will continue (up to 5~ 10 times per second), so that the wheels are always in a rotating state and the braking torque is the maximum.
When a car without ABS is driving, if the brake pedal is pressed hard, the wheel speed will drop rapidly. When the braking force exceeds the friction between the wheel and the ground, the wheel will lock. A fully locked wheel will reduce the friction between the tire and the ground. If the front wheel is locked, the driver can't control the direction of the vehicle. If the rear wheel is locked, it is very easy to slip.
ABS, a technology that was first applied to trains and then to airplanes, is now very popular. Cars with a price of100000 yuan or more can be found, and some buses are also equipped with ABS. Vehicles equipped with ABS can safely control the steering wheel and brakes when encountering slippery roads such as snow, freezing or rainy days. It can effectively prevent accidents and reduce tire wear, but it can't shorten the braking distance of the car, and in some cases it will increase.
Tip: In case of emergency, the ABS system can only be started if the brake pedal is pressed to the bottom. At this time, the brake pedal will shake and sometimes make some noise, but it can't be released, indicating that the ABS system has started to work.
Working principle:
When braking, ABS can quickly judge the locked state of the wheel according to the speed signals from each wheel speed sensor, and close the normally open input solenoid valve above the wheel that starts to lock, so as to keep the braking force unchanged. If the wheel continues to lock, the normally closed output solenoid valve is opened, and the braking pressure on the wheel moves down rapidly due to the pipeline leading to the brake fluid storage tank, thus preventing the wheel from being completely locked due to excessive braking force. At the same time, the main control valve is electrified, and the brake fluid driven by pressure can enter the brake valve. Brake fluid driving the pressure reaches the front wheel input pipeline from the power booster pipeline through the outer edge of the main control valve and the brake master cylinder gasket, and works repeatedly (working frequency is 3- 12 times/second), so that the braking state is always at the best point (slip rate is 20%), the braking effect is the best, and driving is the safest.
The brake fluid in the front cavity of the brake master cylinder is dynamic brake fluid, which pushes the reaction sleeve to move to the right, and the reaction sleeve pushes the booster piston to move the brake pedal push rod to the right. Therefore, when ABS works, the driver can feel the vibration of the pedal on his foot and hear some noise.
After the car slows down, once the ABS computer detects that the wheel locking state disappears, it will close the main control valve, so that the system will enter the normal braking state. If the accumulator pressure drops below the safety limit, the red brake fault indicator and the amber ABS fault indicator will light up. In this case, the driver must pedal deeply with great force to brake the front and rear wheels.
Classification:
One is classified by manufacturers, and the other is classified by control channels. The following mainly introduces the methods of channel classification.
In ABS, the brake pipeline that can independently adjust the brake pressure is called the control channel. The control channel of ABS device is divided into four channels, three channels, two channels and one channel.
(1) Four-channel type: Four-channel ABS has four wheel speed sensors, and each pipeline leading to four wheel brake cylinders has a brake pressure regulator device for independent control, thus forming a four-channel control form. Guangzhou Honda uses a four-channel ABS device.
Performance characteristics: Because the four-channel ABS controls each wheel independently according to the signals input by the wheel speed sensors of each wheel, the utilization rate of adhesion coefficient is high, and the maximum adhesion of each wheel can be utilized to the maximum extent when braking. The four-channel control mode is especially suitable for the road surface with close adhesion coefficient between the left and right wheels of the automobile, which can not only obtain good directional stability and directional control ability, but also obtain the shortest braking distance. However, if the adhesion coefficient between the left and right wheels of a car is quite different (for example, there is water or ice on the road surface), and the ground braking force between the two wheels is quite different when braking, a yaw moment will be generated, which will make the car body lean to the side with greater braking force, and the car cannot keep driving in the predetermined direction, which will affect the braking direction stability of the car. Therefore, drivers should slow down when driving on slippery roads such as local icing or water accumulation, and don't blindly trust ABS devices.
(2) Three-channel type: Three-channel ABS independently controls the two front wheels, and the two rear wheels are jointly controlled according to the principle of low selection (that is, the two wheels are controlled by one channel to ensure that the wheels with less adhesion are not locked), which is also called hybrid control. Santana 2000GSi uses this ABS device.
Performance characteristics: When the two rear wheels are jointly controlled according to the principle of low selection, the braking force of the left and right rear wheels can be guaranteed to be equal in all cases. Even if the adhesion coefficients of the wheels on both sides are quite different, the braking force of the two wheels is limited to a level with small adhesion, so that the braking force of the two rear wheels is always balanced, and the car has good directional stability when braking under various conditions. Of course, when the two rear wheels are controlled together according to the principle of low selection, there may be a problem that the adhesion of the rear wheel with large adhesion coefficient cannot be fully utilized, which reduces the total braking force of the automobile. However, it should be noted that during emergency braking, due to the forward movement of axle load, the proportion of rear wheel braking force in the total braking force of the vehicle decreases, especially in front-wheel-driven vehicles, the adhesion of the front wheel is much greater than that of the rear wheel, and usually the braking force of the rear wheel only accounts for about 30% of the total braking force, and the loss of underutilized adhesion of the rear wheel has little impact on the total braking force of the vehicle.
In the 60 km/h emergency braking contrast test of Santana 2000, the braking distance of vehicles with ABS is only 1 m shorter than that of vehicles without ABS, but vehicles with ABS always have a direction and will not lose control of the direction. The independent control of two front wheels mainly considers automobiles, especially front-wheel drive automobiles. The braking force of the front wheels accounts for a large proportion of the total braking (up to about 70%), so the adhesion of the two front wheels can be fully utilized. On the one hand, the total braking force of the car can be as large as possible, which is conducive to shortening the braking distance; On the other hand, the two front wheels can always maintain large lateral adhesion when braking, so that the car can maintain good steering ability. Although the independent control of the two front wheels may lead to the imbalance of the braking force of the two front wheels, the imbalance of the braking force of the two front wheels has relatively little influence on the stability of the driving direction of the automobile, and the resulting influence can be corrected by the driver's steering manipulation. Therefore, three-channel ABS is widely used in automobiles.
(3) Dual-channel type: Dual-channel ABS is difficult to give consideration to directional stability, steering controllability, braking efficiency and other aspects, and is rarely used at present.
(4) Single-channel ABS: Single-channel ABS is usually called single-channel ABS, that is, a brake pressure regulator is set in the rear wheel brake manifold, and a wheel speed sensor (or one for each rear wheel) is set on the final drive of the rear wheel axle.
Advantages:
When the wheel is about to reach the next locking point, the pressure of brake oil makes the airbag move repeatedly, making it move 60~ 120 times in one second, which is equivalent to continuous braking and relaxation, that is, similar to mechanical? Brake? . Therefore, ABS anti-lock braking system can avoid the out-of-control direction and wheel sideslip during emergency braking, so that the wheels will not lock up during braking and the tires will not rub against the ground at one point, thus increasing the friction force, making the braking efficiency reach over 90%, reducing the braking consumption, and doubling the service life of the brake drum, brake disc and tire. The anti-skid performance of vehicles equipped with ABS can reach 80% on dry asphalt road, rainy day and snowy day respectively? 90%、30%? 10%、 15%? 20%。
Use tips:
Anti-lock braking system can improve the stability and braking performance of vehicles under most braking conditions. This system will automatically? Pulsating step? Brake to avoid wheel lock.
Electronic braking force distribution (EBD) can prevent excessive braking of the rear wheel and better control the effective braking force applied to the rear wheel axle.
When the vehicle speed exceeds 1 1 km/h (7 mph), you may also hear a slight click and some motor noises. These noises are the performance of the system's periodic self-inspection to ensure the normal operation of the anti-lock braking system. This self-inspection will be carried out every time the vehicle starts and accelerates more than 1 1 km/h (7 mph).
Under some road conditions or braking conditions, the vehicle will start the anti-lock braking system during braking. Anti-lock braking system can be started in road conditions including ice, snow, gravel, bumps, tracks, loose rock or emergency braking.
When the braking system enters the anti-lock state, you may also encounter the following situations:
& lt 1 & gt； Anti-lock braking system motor is running (it may continue to work for a short time after parking);
The<2> solenoid valve makes a clicking sound when acting;
& lt3> brake pedal pulsation;
& lt4> In the final stage of braking, the brake pedal will drop slightly or slowly.
These are normal features of anti-lock braking system.
Anti-lock braking system has sophisticated electronic equipment, which may be interfered by improper installation or high-power radio transmitting equipment. These disturbances may lead to the loss of anti-lock braking ability. This kind of equipment should be installed by qualified experts.
Pressing the brake pedal continuously will reduce the performance of anti-lock braking and may lead to an accident. Pressing the brake pedal continuously will increase the braking distance. If you want to slow down or brake suddenly, please keep pressing the brake pedal.
Driving safety:
Tip:
& lt 1 & gt； Anti-lock braking system (ABS) can't prevent physical laws from acting on the car, and it can't improve the braking or steering efficiency beyond the conditions provided by the car's own braking force, tires or traction.
& lt2 & gtABS cannot prevent accidents caused by turning at high speed, following the car too tightly or slipping tires on wet roads. To avoid accidents, we can only rely on drivers' safe and dedicated driving and skilled operation techniques.
& lt3> Do not overuse the functions of a car equipped with ABS in reckless and risky driving mode, which will threaten the safety of the driver himself and others. All wheels of the vehicle must have the same tire size and type, and the tires must be properly inflated in order to send an accurate signal to the computer.
ABS warning light:
The ABS warning light will monitor the anti-lock braking system. When the ignition switch is turned to the ON position, the warning light will remain on for 4 seconds.
If the ABS warning light is on all the time or while driving, it means that the anti-lock part of the braking system is useless and must be repaired. However, if the brake warning light does not light up, it means that the conventional braking system can still work normally.
If the ABS warning light is on, the braking system should be overhauled as soon as possible to restore the function of the anti-lock braking system. If the ignition switch is turned to the on position, but the ABS warning light is not on, please repair this light bulb as soon as possible.
If the brake warning light and ABS warning light are on, the anti-lock braking system (ABS) and electronic braking force distribution system (EBD) will lose their functions. The anti-lock braking system must be repaired immediately.
Anti-lock braking system ABS @20 19