Anti-lock Braking System (ABS)
ABS is an improved technology based on the conventional brake device, and it is a kind of automobile safety control system with the advantages of anti-skid and anti-lock. Anti-lock brake is essentially an enhanced or improved type of ordinary brake.
Anti-lock braking systems are designed to prevent brake locking and wheel slippage when braking is difficult or on wet or slippery surfaces, which adds a significant range of safety to everyday driving by preventing the vehicle from sliding dangerously and allowing the driver to maintain steering control when trying to stop. ABS not only has the braking function of ordinary braking system, but also can prevent wheel lock, so that the car can still turn under braking state, ensure the stability of the braking direction of the car, and prevent sideshow and deviation, is the most advanced braking device on the car with the best braking effect.
Anti-lock braking system is to prevent the wheel from being locked in the braking process, which can cause: the road braking force decreases and the braking efficiency decreases; Reduce the service life of the tire, when the car brakes the front wheel lock, the car will lose the steering ability, the side force is reduced when the rear wheel lock, the direction stability of the brake is reduced, which will cause the car to turn sharply and throw the tail or sideslip. The impact of anti-lock braking system on vehicle performance is mainly manifested in reducing braking distance, maintaining steering ability, improving driving direction stability and reducing tire wear. In the event of an emergency, the driver only needs to press the brake pedal as hard as possible and not release it, and the other things are handled by the ABS, so the driver can concentrate on dealing with the emergency and ensure the safety of the car.
The abbreviation of anti-lock braking system is ABS, and the full name of the English is anti-lock Brakingsystem, or Anti-skidBrakingSystem. First of all, "hold" refers to the brake pad (or shoe) and the brake disc (brake drum) without relative sliding friction, the friction pair friction heat when braking, the car kinetic energy into heat, and finally let the car stop or slow down; Secondly, the wheel lock actually refers to the car in the emergency braking, the wheel is completely stationary and does not rotate, it refers to the car in the braking process once, the tire is no longer rotating, when the car brakes, the car will give the wheel a force that enables it to stop, so that the wheel can not continue to rotate, but the wheel has a certain inertia, after the wheel has stopped rotating, It will continue to slide forward for some distance before finally coming to a complete stop. If the front and rear wheels of the car are not in the same straight line, because of the inertia, the front and rear wheels will glide towards their respective fronts. According to the test of tire limit braking, the tire cannot provide side grip when the linear braking is saturated, and the vehicle will be difficult to complete any side control. In this way, the front and rear wheels will run in two different directions and the vehicle will have uncontrollable yaw (spin), and the car will throw its tail. In this case, the steering wheel of the car does not have any effect, the car will completely lose control, if the situation is very serious, it is likely to overturn the car, causing traffic accidents and other hazards.
If the brakes are completely locked, this energy conversion can only depend on the friction between the tire and the ground. Friction is divided into two kinds: rolling friction and sliding friction, friction coefficient depends on the influence of road dry humidity, when the brake wheel and the ground friction will gradually increase, large to a critical point after it will change from rolling to sliding friction. The sliding friction force will gradually decrease, so ABS is to use the principle of this friction curve to fix the friction force of the wheel at this peak, so as to reduce the braking distance. Severe friction makes the tire rubber high temperature, local liquefaction of the contact surface, shortening the braking distance, but sideslip will accelerate wear.
Anti-lock Braking System (ABS) is one of the research contents of vehicle longitudinal dynamics control. Anti-lock braking, as the name suggests, is to prevent the car from braking once, using intermittent braking. It refers to the automatic adjustment of the braking torque (wheel braking force) acting on the wheel during the braking process to prevent the wheel from locking when the braking torque is large; At the same time, the modern ABS system can determine the slip rate of the wheel in real time, and keep the slip rate of the wheel in the brake near the optimal value. Therefore, when the ABS system works, the driver will not lose control of the steering of the vehicle due to the front wheel lock, and the braking distance of the car will be smaller than the wheel lock, so as to achieve the best braking efficiency and reduce the impact force when the accident occurs.
