What is the working principle of ABS?
2 Answers
ABS system, also known as the Anti-lock Braking System, operates on the following principle: During braking, ABS monitors speed signals from each wheel speed sensor. It closes the normally open input solenoid valve for wheels that begin to lock, maintaining constant braking force. If the wheel continues to lock, it then opens the normally closed output solenoid valve. This keeps the braking state at its optimal point, ensuring the best braking performance and maximum driving safety. ABS, short for Anti-lock Braking System, functions by automatically controlling the braking force during vehicle deceleration to prevent wheel lock-up. It maintains the wheels in a rolling-sliding state (with a slip ratio of about 20%), thereby maximizing the adhesion between the tires and the road surface. The ABS system primarily consists of four components: wheel speed sensors, electronic control unit (ECU), hydraulic unit, and ABS warning light. The wheel speed sensors detect the motion state of each wheel, generating sinusoidal AC electronic pulse signals. These signals are then processed by a modulator, converted into digital signals, and transmitted to the electronic control unit. The central electronic control unit (ECU) receives input signals from the wheel speed sensors. Using these parameters, it calculates wheel speed, vehicle speed, and slip ratio. Based on the slip ratio, it determines wheel status and issues control commands to the hydraulic unit. The hydraulic unit adjusts brake line pressure according to control commands, with the regulation process including pressure maintenance, pressure increase, and pressure reduction. The ABS warning light alerts the driver to potential system malfunctions. If the ABS warning light illuminates, it is advised not to continue driving. An illuminated ABS light indicates a malfunction in the vehicle's anti-lock braking system. During emergency braking, locked wheels could cause the vehicle to skid uncontrollably, preventing the driver from decelerating or adjusting the vehicle's trajectory, which poses significant safety risks.
ABS sounds complicated, but it's essentially a smart braking assistant. I think its working principle is quite similar to how the human brain handles emergencies. Simply put, the car has wheel speed sensors that constantly monitor the rotation speed of each wheel. If the wheels are about to lock up during hard braking, the computer immediately instructs the hydraulic modulator to reduce brake pressure, allowing the wheels to keep turning slightly and avoid lock-up. This enables you to steer while braking to avoid obstacles, right? I've personally experienced ABS kicking in on slippery rainy roads – the car remained stable without skidding, and I'm truly grateful for this technology. For maintenance, remember to check for sensor and wiring wear to prevent system failure. Almost all modern cars come with ABS as standard, significantly improving safety.
