Electromechanical Brake Booster, Basic Function - GF42.31-P-2003A
Model all (4xWD, CAR)
Example illustration of electromechanical brake booster
Overview
This document contains information on:
- General
- Function requirements
- Function
- Normal function
- De-energized operation
General
The electromechanical brake booster boosts the brake force applied by the driver. If the driver depresses the brake pedal, the brake force is supported by an electric motor. Without electrical assistance, the brake operates hydraulically without any support.
More efficient combustion engines, hybrid drives, electric vehicles as well as modern driving assistance functions require a vacuum-independent brake system. The electromechanical brake booster can generate the necessary brake force, without the pedal force applied by the driver.
Function requirements
- Drive train operational
Electromagnetic brake booster
Function
Normal function
The driver initiates a brake request by depressing the brake pedal. The brake pedal moves the piston of the brake booster. The diaphragm travel sensor (2) detects the difference between gap A (a) and gap B (b). The brake unit control unit is regulated such that the distance between gap A (a) and gap B (b) remains the same. The brake unit control unit actuates the electric motor (5), which moves the spindle (3) via the gear-only transmission (4). The spindle (3) is moved until the distance between gap A (a) and gap B (b) is the same again. If the brake pedal is no longer operated, the spindle (3) is moved in the opposite direction and the brake pressure is reduced.
De-energized operation
If the supply voltage fails, the electric motor (5) cannot provide support. If the brake pedal is actuated, this moves the guide piston (7) and thus force is directly applied to the master cylinder. The guide piston (7) moves freely into the longitudinal grooves within the spindle.
Autonomous function
Brake applications in autonomous driving operation are forwarded electronically by the ESP® control unit to the brake unit control unit. The control system forwards the signal to the electric motor (5), which moves the spindle (3) via the gear-only transmission (4). The spindle (3) is moved until the desired brake pressure is reached. In the case of autonomous brake applications, gap B (b) is closed. If the spindle (3) is moved further when gap B (b) is already closed, the brake pedal also moves. The driver can brake manually at an time by actuating the brake pedal
| Component descriptions | |||
|---|---|---|---|
| Electronic brake system control unit, component description | Model 223 | GF42.25-P-3140A | |
| Model 206 | GF42.25-P-3140C | ||
| Model 297 | GF42.25-P-3140D | ||
| Model 295 | GF42.25-P-3140E |