Unit 10 Anti-lock Brake System 汽车专业英语教学课件.ppt

Unit 10 Anti-lock Brake System Unit 10 Anti-lock Brake System The ABS is a four-wheel system that prevents wheel lock-up by automatically modulating the brake pressure during an emergency stop. By preventing the wheels from locking, it enables the driver to maintain steering control and to stop in the shortest possible distance under most conditions[1]. During normal braking, the ABS and non-ABS brake pedal feel will be the same. Unit 10 Anti-lock Brake System Unit 10 Anti-lock Brake System During ABS operation, a pulsation can be felt in the brake pedal, accompanied by a fall and then rise in brake pedal height and a clicking sound. Vehicles with ABS are equipped with a pedal-actuated, dual-brake system. The hydraulic system consists of the following: (1)??ABS hydraulic control valves and electronic control unit. Unit 10 Anti-lock Brake System (2)??Power brake booster. (3)??Brake master cylinder. (4)??Necessary brake tubes and hoses. The anti-lock brake system consists of the following components: (1)??Hydraulic Control Unit (HCU). (2)??Anti-lock brake control module. Unit 10 Anti-lock Brake System (3)??Front anti-lock brake sensors/rear anti-lock brake sensors. (4)??Anti-lock Brake System (ABS) operates as follows: When the brakes are applied, fluid is forced from the brake master cylinder outlet ports to the HCU inlet ports. This pressure is transmitted through four normally open solenoid valves contained inside the HCU, then through the outlet ports of the HCU to each wheel. Unit 10 Anti-lock Brake System The primary (rear) circuit of the brake master cylinder feeds the front brakes. The secondary (front) circuit of the brake master cylinder feeds the rear brakes. If the anti-lock brake control module senses that a wheel is about to lock, based on anti-lock brake sensor data, it closes the normally open solenoid valve for that circuit. This prevents any more fluid from entering that circuit[2]. Unit 10 Anti-lock Brake Sy