The most important part in the fuel consumption measurement system is the flowtronic sensor, which acts as measuring cell and which is installed into the fuel supply system of the internal combustion engine. The measuring cell captures the fuel volume flowing through it. The complete measurement equipment may need additional components to aid the flowtronic sensor.

The Sensor Design

The mode of measurement is based on a 4-piston counter, in which the known piston volume is used to determine measured volume.

The displacement of the pistons due to the fuel flow turns the crankshaft. The integrated hall transducers detect the rotation of the crankshaft and create output pulses.

First, fuel is forced from the crankshaft space into the cylinders. At the opposite side, the cylinder content is drained into the ring main pipe. As this happens, the rotation of the crankshaft is transformed into electrical pulses.

The crankshaft is equipped with a magnet, e.g. a six pole magnet. The rotating magnetic field is monitored with two hall sensors. The hall sensors are physically displaced by 90°, so that their signals are delayed by 90°. The calculation unit is able to calculate the correct volume, even if the fuel flow direction changes.

Fuel Determination Procedure

Each full rotation of the crankshaft generates a certain number of pulses. An ascending and descending flank is registered from each pulse, so that twice of the certain number of pulsescan be used by the signal electronic.

The total amount of pulses at the outlet of the external signal electronic represents the amount of incremental volume units at the inlet of the external signal electronic.

The measuring cell has a pre-defined positive fuel flow direction, which may change in the application according to the actual condition of the fuel supply system. The signal electronic of the flowtronic sensor detects the direction of the fuel flow and increases or decreases the measured volume respectively. This ensures, that the pulses at the outlet of the signal electronic equal the measured volume.

The data acquisition system needs to count the pulses. The sum of the pulses is multiplied by the volume factor, which is specific for each sensor. The result is the total volume measured by the sensor.

Protection against Damage

All flowtronic systems are protected by fuel filters against damages caused by particles within dirty fuel. However the sensor S8005C is equipped with two filters as fuel can flow in both directions.

Fuel filters must be replaced according to the relevant operation manual.

Further information on fuel filters ...