Hot film mass air flow sensor, function - GF07.07-P-4118-02GS
Schematic representation
The electronics in the hot film mass air flow sensor control the temperature of the heating resistor (R H ) by means of a variable voltage so that its temperature is 160°C above the intake air temperature detected by the temperature resistor (R L ).
The temperature of the thermistor is measured over the sensor resistance (R S ).
Temperature changes which take place as a result of an increased or decreased flow of air regulate the electronics according to the voltage of the thermistor until the temperature difference of 160°C is again reached. This control voltage is used by the engine control unit as a measure for the metered air mass.
The intake air temperature is measured by a further NTC resistance in the hot film mass air flow sensor.