Automotive LE - ABS Process Discussion and Presupposition

The electronic controller (ECU) is the core of the ABS device. It consists of the vehicle speed signal calculation circuit, logic control circuit, safety alarm circuit, and internal monitoring correction circuit. The vehicle speed signal calculation circuit is used for testing. When the vehicle speed exceeds 10K/h, the ABS control program is automatically started to make it enter the working state; the logic control circuit is to input the vehicle speed information (acceleration and deceleration signals of the car) and left and right front and rear wheels. The rotation speed is calculated and compared. If an abnormal rotation of the wheel is found, an instruction is issued to the solenoid valve of the brake pressure regulator to adjust the brake pressure to ensure that each wheel cylinder can cooperate with the stable brake without locking; safety The alarm circuit is used to reflect the fault condition of the ABS control circuit. If there is a fault, this circuit will convert the ABS brake mode mode to the normal brake mode (ECU will automatically turn off the ABS brake mode, start the normal brake mode, and alert the driver).

The ABS-ECU internal monitoring and correction circuit supervisor monitors each solenoid valve and the battery voltage, and monitors the pressure in the control brake circuit, and automatically corrects the ABS control program. If a circuit defect is detected, it will immediately alarm.

A typical brake oil pressure regulator controls the pressure of the pipeline through a solenoid valve; the brake oil pressure regulator is realized through three basic actions of “boost, depressurization, and pressure keeping, to prevent the system from locking up.

Japanese Mitsubishi PAJERO-im type off-road vehicle electronic control ABS circuit Japanese Mitsubishi PAJERO-im type off-road vehicle electronic control ABS circuit.

Defects in the speed sensor ECU brake oil pressure regulator As we all know, to measure the braking effect of a car, we must judge the effect with the value of the slip rate. From the circuit diagram, it can be seen that the anti-lock brake system of Japanese Mitsubishi PAJERO-im off-road vehicle mainly uses the wheel speed sensor to control the magnitude of the braking force to achieve the purpose of anti-lock braking, and the wheel speed sensor can only determine the rotation of the wheel. The speed does not use the slip rate to control the magnitude of the braking force. Therefore, theoretically and practically speaking, the anti-lock brake system of Japan's Mitsubishi PAJERO-im off-road vehicle is flawed.

Improve the strategy to change the wheel speed sensor to a slip rate sensor. Improved circuit diagram. After the improvement, the slip rate signal was synthesized by the laser speedometer and the gear sensor. The slip rate signal was used to control the magnitude of the braking force, ie, the photoelectric control of ABS was achieved.