SBC Control Unit, Function

SBC Control Unit, Function







Functional diagram
A7/3m1 High-pressure charging pump
A7/3n1 SBC control module
X11/4 Data link connector

Function
The SBC control module (A7/3n1) is divided up functionally as follows:
- Signal conditioning
- Function logic component
- Safety circuit

Signal conditioning
The following input signals are processed by the function logic component for calculations or as information:
- Brake pedal speed
- Signal from SBC pedal value sensor (B37/1)
- Signal from front axle pre-pressure sensor (A7/3b1)
- Calculation for actuation of high-pressure charging pump (A7/3m1)
- Signal from reservoir sensor
- The vehicle speed - Signals from wheel speed sensors

Function logic component
The conditioned input signals are processed in the logic component and converted into output signals.
- Signals from rpm sensors:
The 4 wheel speed signals are transmitted to the ESP, SPS and BAS control module (N47-5) via the CAN-SBC and discrete lines.
- Signals to ESP, SPS and BAS control module (N47-5):
The wheel pressure signals from all 4 wheels, the signal from the brake lamp switch (S9/1), the front axle pre-pressure signal, the reservoir pressure and the pedal travel are transmitted via the CAN-SBC to the ESP, SPS and BAS control module (N47-5) for further processing.
- Pressure regulators:
The pressures calculated by the ESP, SPS and BAS control module (N47-5) are applied at the brake calipers of the individual wheels.
- Basic braking function:
The basic braking function is made available for the brake booster and a permanently installed brake force distributor if the ESP, SPS and BAS control module (N47-5) fails or communication between the ESP, SPS and BAS control module (N47-5) and the SBC control module (A7/3n1) fails or is erroneous.
- Brake servo assistance in leading and trailing phase:
The SBC control module (A7/3n1) provides the necessary brake servo assistance during the leading and trailing phase.

Safety circuit
The safety circuit detects faulty signals from sensors, faults in the control module and in the electric line system. Actuation of the high-pressure charging pump is monitored during the control process. The solenoid valves are monitored permanently. If a fault is detected, the system is switched off and this is indicated to the driver by means of the multifunction display (A1p13) in the instrument cluster (A1). In addition, a fault code is stored in the control module.
The safety circuit also constantly monitors the battery voltage. If the voltage drops below 8.5 V or rises above 17.4 V, the system is again shut down or is only partly functional until the voltage returns to the specified range.