B-Pillar Satellite, Right (SBSR)
B-Pillar Satellite, Right (SBSR)
The SBSR is located in the right side B-pillar above the seatbelt inertia reel. The SBSL contains a sensor for transverse acceleration only.
The right side B-pillar satellite is responsible for deploying the passenger seatbelt tension limiter, the battery safety terminal (BST) and for operating the fuel pump (EKP).
The satellite SBSR is connected to the SIM via the byteflight. The power supply of the satellites is also from the SIM and it is buffered by the memory backup capacitor.
The voltage supply of the electric fuel pump is by means of a separate terminal 30.
In the sleep mode of the byteflight, the power supply of the SBSR is switched off by the SIM; the operating voltage of the electric fuel pump is unaffected by this.
The "watchdog" function is run by the SIM.
Sensor
An acceleration sensor for the transverse acceleration is integrated in the SBSR. The sensor provides a variable voltage. This voltage is a measurement of the vehicle's sideways acceleration.
The ignition stages are diagnosed and controlled by the ignition ICs. The self-diagnosis of the trigger circuits during the pre-drive check and in normal operation is the same for all satellites. (See SASL)
Electronic Control of the Fuel Pump
The SBSR of the ISIS system controls the fuel pump delivery rate during operation of the vehicle and fuel supply cutoff in the event of a crash.
The advantages of having a variable fuel pump delivery rate are:
- Reduction of tank warming (evaporative emissions reduction).
- Reduction of the power consumption by approx.50 Watts.
- Increase of the fuel pump service life.
- Integration of crash deactivation.
- Elimination of the fuel pump (EKP) relay.
The fuel is supplied depending on consumption. The DME (ECM) determines a fuel requirement in liters per hour (l/h).
The SBSR receives the fuel requirement from the DME (ECM) via the PT-CAN and the byteflight. If the fuel requirement from the DME (ECM) fails, or the bus system is defective, the fuel pump is operated at maximum speed (default).
The delivery volume of the fuel pump is regulated by the electronic control of the EKP voltage supply.
In the microprocessor, the required quantity from DME (ECM) is converted into a pulsewidth-modulated signal and transmitted to the EKP controller. The adjustable pulse width produces a variable voltage that is used to operate the fuel pump.
The current consumption (Amps) of the pump is measured in the EKP controller, this determines the rotation speed of the pump. The rotation speed is transmitted to the microprocessor, which calculates the current fuel delivery volume. The delivery volume is checked using a setpoint / actual comparison and the control voltage is corrected if necessary.
Fuel Cutoff After a Collision
If the ISIS system detects a crash of sufficient severity, the fuel pump is shut down to prevent a possible fire if fuel lines under the hood were to be damaged. The fuel pump can then be reactivated by switching the ignition off and on. At that point the fuel pump is again ready for operation.