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 pulse-width-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.