The wheel speed sensor is a detecti

The wheel speed sensor is a detection element for the wheel speed of an automobile. It can generate an approximate sinusoidal electrical signal whose frequency is proportional to the wheel speed. The ABS control unit calculates the wheel speed based on the processed signal. The electronic control unit is the core control component of the entire anti-lock braking system. It receives the frequency signal from the wheel speed sensor, generates corresponding control electrical signals through calculation and logic judgment, and operates the solenoid valve to adjust the brake pressure. Qualitatively speaking, when the slip rate of the wheel is not within the control range, the ECU outputs a control signal to command the solenoid valve to open or close, thereby adjusting the brake wheel cylinder pressure, causing the wheel speed to increase or decrease, and the vehicle The wheel slip rate is controlled within a certain range to achieve safe and reliable braking of the car. The schematic diagram of the electronic control unit is shown in Figure 3-3.The solenoid valve is the executive part of the anti-lock brake system. In the absence of a control signal, the brake system is equivalent to a conventional brake system, which directly outputs the maximum brake pressure; when the ECU sends a control signal to the solenoid valve, the solenoid The valve action adjusts the pressure of the wheel cylinder, thereby adjusting the slip rate of the wheel, so that the braking force fluctuates in the area close to the peak, but does not reach the peak braking force, and achieves the best braking efficiency.ABS is to continuously detect the change of wheel speed during the braking process of the car, and according to a certain control method, the brake wheel cylinder pressure is adjusted through the solenoid valve to obtain the highest longitudinal adhesion coefficient, so that the wheels are always in a good braking state.