How does the ABS sensor in a car work?
1 Answers
ABS system, also known as the Anti-lock Braking System, works as follows: During braking, the ABS closes the normally open input solenoid valve on the wheel that begins to lock based on speed signals from each wheel speed sensor, keeping the braking force constant. If the wheel continues to lock, the normally closed output solenoid valve is opened. This ensures the braking state remains at the optimal point, achieving the best braking effect and maximum driving safety. ABS, short for Anti-lock Braking System, functions by automatically controlling the braking force during vehicle braking to prevent wheel lock-up. It maintains the wheels in a state of rolling and sliding (with a slip ratio of around 20%), ensuring maximum traction between the wheels and the road. The ABS system primarily consists of four components: wheel speed sensors, the electronic control unit (ECU), the hydraulic unit, and the ABS warning light. The wheel speed sensors detect the motion state of the wheels and generate sinusoidal 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 and uses them to calculate the wheel speed, vehicle speed, and slip ratio. Based on the slip ratio, it determines the wheel's condition and issues control commands to the hydraulic unit. The hydraulic unit adjusts the pressure in the brake lines according to the control commands, with the adjustment process including pressure maintenance, pressure increase, and pressure reduction. The ABS warning light alerts the driver to any system malfunctions. If the ABS warning light illuminates, it is advisable not to continue driving. An illuminated ABS light indicates a malfunction in the vehicle's anti-lock braking system. During emergency braking, if the wheels lock up, the vehicle may skid uncontrollably, preventing the driver from slowing down or adjusting the vehicle's trajectory, posing significant safety risks.
