Analysis of technical principle and classification advantages and disadvantages of electronically controlled hydraulic braking system

Classification of electronically controlled hydraulic braking systems According to different technical routes, electronically controlled hydraulic braking systems can be divided into three categories: traditional electronically controlled hydraulic braking systems (the first generation), electronically controlled vacuum assist systems (EVP) and electromechanical servo hydraulic assist systems (the second generation). Under the normal working condition of the traditional electro-hydraulic braking system, when braking is needed, the driver presses the brake pedal. After the brake pedal is displaced, the pedal sensor converts it into an electrical signal and sends it to the electronic control unit (ECU). Through analysis and judgment, adjust the braking pressure generated by accumulator or solenoid valve. At the same time, ECU receives and processes the vehicle dynamic data from ABS/ASR/ESP, and sends control signals to the corresponding control units to achieve optimal control. If the system fails, the ECU will switch to the emergency braking mode, and the hydraulic pipeline of brake pedal force will communicate with the emergency braking pipeline, and the pedal force will be loaded on the brake through the hydraulic pipeline. Electronic control vacuum booster system when the vacuum booster can't get vacuum or the vacuum is insufficient (at high altitude, low temperature, fuel-saving engines, diesel engines, new energy vehicles, etc.). ), it will lead to poor braking system assistance effect. The electric vacuum booster system can monitor the vacuum change in the booster through the vacuum sensor and the atmospheric pressure sensor, and judge the working opportunity of the vacuum booster pump through logic, so as to provide appropriate auxiliary power for the braking system and ensure that it can provide sufficient braking force effect for the driver under various working conditions. Electromechanical servo power system The electromechanical servo system is represented by iboster of Bosch Company, and its working principle is similar to the traditional vacuum booster. During normal operation, the driver presses the brake pedal, and the pedal travel sensor integrated in iBooster detects the displacement signal and sends it to the electronic control unit. The control unit calculates the torque required by the motor, and then converts the torque into the servo braking force of the booster valve body through a two-stage gear device. The output force of the booster valve body and the input force of the booster input rod are converted into the brake fluid pressure in the brake master cylinder. IBooster adopts double safety failure mode. Integrated hydraulic system The integrated hydraulic system is represented by the Integrated Brake System (IBC) of Tianhe Company. Its working principle is similar to that of iBooster products, but it is more integrated. The integrated unit replaces a large number of independent components required for low vacuum or non-vacuum systems, including electronic stability system (ESC), vacuum booster and related cables, sensors, switches, electronic controllers, vacuum pumps, etc. The core of the system is the actuator driven by the ultra-high speed brushless motor, which is monitored by the rotary encoder, and the encoder provides data such as motor speed, speed and position to the central electronic control unit (ecu). At the same time, an independent hydraulic circuit is integrated to convey the driver's braking intention to the system. Compared with the traditional electro-hydraulic braking system, the technical routes of electronic vacuum power system and electro-hydraulic power system are different, and each has its own advantages and disadvantages. According to different technical strategies, the electronic braking system can be divided into electromechanical servo power systems represented by Bosch iBooster and Trina IBC.