ABS/ESP braking system test bench
Nov 12, 2021
New design of Automotive training stands , it widely use training station .
The Automotive Teaching Equipment of ABS/ESP braking system test bench instructions as follows:
The basic working principle of ABS system is: in the process of emergency braking of the car, in order to prevent the phenomenon of car wheels holding dead, resulting in the decline of braking performance and loss of steering ability, the best measure is to repeatedly step down and relax the brake pedal.However, when there is an emergency, it is difficult to operate this process in a very short time. However, the ANTI-lock braking system uses THE ABS control unit (ECU) to monitor the speed of the four wheels in the braking process, so as to control the brake pressure of the ABS hydraulic control unit brake wheel cylinder, so as to avoid the wheel locked.The ABS electronic control unit (ECU) continuously receives the speed signal from the speed sensor of the four wheels, and the ECU carries on the relevant processing and calculation according to the signal of the input of the four speed sensors, and obtains the slip rate of each wheel of the car.When the ECU detects a wheel slip rate is greater than the set value, it will send out the instructions to control the hydraulic control unit, the brake of the wheel brake wheel cylinder pressure decreases, and when the ECU detects a wheel slip rate is less than the set value, it will send relevant commands to control the hydraulic unit, put the wheel brake pressure increase,When the ECU detects that a wheel slip rate is close to a set point, it issues instructions to control the hydraulic control unit to keep the wheel brake pressure at a certain level.In this way, each sensor of the wheel can be controlled in an ideal range, so that the wheel will not be completely locked.
In the braking process of the car, when the ECU does not monitor the wheel has a tendency to lock, the ABS system will not participate in the braking and work.
2. Structure and working principle of main parts of ABS system
2.2.1 Wheel speed sensor
The wheel speed sensor detects the speed of the wheel and transmits its signal to the ABS electronic control unit. The BOSCH5.3 ABS system has four-wheel speed sensors. The tooth ring of the front wheel is installed on the driveshaft, and the speed sensor is installed on the steering knuckle of the automobile, as shows.The rear-wheel ring is mounted on the rear hub of the car, and the speed sensor is mounted on a fixed bracket.
1. Electronic control unit
The electronic control unit is the control center of the ABS system. It is a microcomputer, so it is often called ABS(ECU) computer.The ECU of ABS receives the speed signal from the sensor on the wheels, and then sends instructions to the ABS actuator after the signal is reshaped and amplified by the circuit and compared, analyzed and discriminated by the computer.The ABS ECU also has the functions of initial detection, troubleshooting, speed sensor detection and system failure protection.The basic function of THE ECU of ABS is that it uses the signal of the wheel speed sensor to calculate the speed and acceleration of the wheel, so as to calculate the speed and slip rate. The pressure regulator is used to control the braking pressure of each wheel cylinder, so as to control the movement of the vehicle and prevent the wheel from being locked.
(1) Composition: ECU is encapsulated in a metal shell, and connected to the sensor and actuator through a wire harness by using a multi-pin interface.To ensure the reliable operation of the ECU, it is generally installed in the dust and moisture invasion, electromagnetic interference is small.
(2) Internal structure: In order to ensure the safety and reliability of the system, two identical microprocessors are adopted in the ECU of many ABS, one for system control and the other for detection.They perform operations using the same program. Once the detection ECU finds that its calculation results are inconsistent with those of the control ECU, the ECU immediately pulls the braking system out of the ABS control and only maintains the conventional braking.This approach ensures a more secure system.
2. Hydraulic control unit and hydraulic pump
The hydraulic control unit is installed between the brake master cylinder and the brake wheel cylinder, adopting an integral structure (as shows).The main task is to automatically adjust the hydraulic pressure in the brake according to the instruction of ABS ECU.