absWhat does anti-lock braking system meanabs The working principle and function of the anti-lock braking system
The anti-lock braking system (antilock brake system ) referred to as ABS. The function is to automatically control the braking force of the brake when the car is braking, so that the wheels will not be locked and will slide while rolling (the slip rate is around 20%) state to ensure that the adhesion between the wheel and the ground is at the maximum value.
Performance Features
What is the function of the ABS system?The anti-lock braking system can improve the safety factor of emergency braking of the vehicle when driving. In other words, if a car without ABS is prone to tire lockup when the car applies emergency braking in an emergency, that is, the steering wheel cannot rotate, the risk factor will decrease. As it increases, it can easily lead to serious consequences.
Single-channel ABSGenerally, the two rear wheels are controlled together according to the low-selection principle. Single-channel ABS cannot fully utilize the adhesion of the two rear wheels, so the braking distance may not be significantly shortened. In addition, the front wheel braking is not controlled. The front wheel will still lock during braking, so the steering control ability is not improved. However, since the two rear wheels will not lock during braking, the braking performance can be significantly improved. The directional stability is a major advantage in terms of safety, and it has the advantages of simple structure and low cost, so it is widely used in light trucks.
To sum up, although the ABS device has the function of shortening the braking distance, in addition, different types of ABS span>The prices of devices vary greatly due to reasons such as their composition and structure. Therefore, when purchasing a car, you should not only look at the price, but also what type of ABS is usedABS device.
Advantages
When the wheel is about to reach the next locking point, the pressure of the brake fluid causes the airbag to act repeatedly, so that it can act 60~120 times in one second, which is quite Constantly braking and relaxing is similar to mechanical “point braking”. Therefore, the ABS anti-lock braking system can prevent direction loss and wheel slippage during emergency braking, prevent the wheels from being locked during braking, and prevent the tires from moving in one direction. friction with the ground, thus increasing the friction and making the braking efficiency reach more than 90%. At the same time, it can also reduce braking consumption and extend the length of brake drums, discs and tires. Twice the lifespan. The anti-skid performance of vehicles equipped with ABS reaches 80% on dry asphalt roads, rainy days, snowy days and other roads respectively. —90%, 10%—30%, 15%—20%.
Limitations
ABSThe system itself also has limitations, and it still cannot escape certain physical laws. In both cases, the ABS system cannot provide the shortest braking distance. One is to brake directly by an experienced driver on a smooth dry road. Another situation is braking on loose gravel, loose dirt or deep snow.
In addition, usually on dry roads, the latest ABS system can control the slip rate to 5%—20% range, but not all ABS operate at the same rate or the same level to brake. Although the four-wheel anti-lock braking system can brake the car in the shortest possible distance, if the braking is performed too late and the car cannot come to a complete stop before colliding with the obstacle, it still cannot prevent the accident from happening. .
Wheels
When braking, ABSaccording to eachThe speed signal from the wheel speed sensor can quickly determine the locked status of the wheel, close the normally open input solenoid valve on the wheel that starts to lock, and keep the braking force unchanged. If the wheel continues to lock, open the normally closed output solenoid valve. Valve, the brake pressure on this wheel quickly decreases due to the emergence of a pipeline directly connected to the brake fluid reservoir, preventing the wheel from completely locking due to excessive braking force. When the braking state is always at the optimal point (the slip rate S is 20%), the braking The effect is the best and driving is the safest.
The brake fluid in the chamber in front of the brake master cylinder is dynamic pressure brake fluid. It pushes the reaction sleeve to move to the right, and the reaction sleeve pushes the booster piston to make the brake The pedal pusher moves to the right. Therefore, when ABS is working, the driver can feel the vibration of the pedals on his feet and hear some noise.
After the car decelerates, once the ABS computer detects that the wheel lock state has disappeared, it will close the main control valve, causing the system to switch to Work under normal braking conditions. If the pressure in the accumulator drops below the safe limit, the red brake malfunction indicator light and the amber ABS malfunction indicator light come on. In this case, the driver needs to use a large amount of force to apply deep pedal braking in order to effectively brake the front and rear wheels.
Function
① Give full play to the effectiveness of the brake and shorten the braking time and distance.
② It can effectively prevent the vehicle from slipping and drifting during emergency braking, and has good driving stability.
③ It can turn during emergency braking and has good steering maneuverability.
④ It can avoid severe friction between the tire and the ground and reduce tire wear.
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