P09.20-2350-79
Shown on engine 608 |
1 | Hot film mass air flow sensor |
P07.07-A005-79
Shown on engine 656 |
1 | Hot film mass air flow sensor |
Overview
This document contains information on:
General
Location
Function
General
The hot film mass air flow sensor records the intake air mass flow (kg/h). The integrated intake air temperature sensor records the intake air temperature.
The combustion engine control unit requires the air mass and the intake air temperature to be recorded for measuring the load and determining the cylinder charge.
The intake air temperature sensor is integrated in the hot film mass air flow sensor.
Location
The hot film mass air flow sensor is located between the air filter and the throttle valve actuator.
1 | Hot film mass air flow sensor |
2 | Intake air temperature sensor |
P07.07-A006-75
Function
The hot film mass air flow sensor includes a sensor plate. The resistances are applied as a thin resistance film. The sensor is kept at a constant temperature of approx. 160 °C. The cooling of the sensor, which is caused by intake air blowing by, is compensated again by the heating current. The intake air mass can be determined via the heating current required for compensation of the temperature difference.
This control current is converted into a pulse width modulated signal by the hot film mass air flow sensor. The combustion engine control unit requires the pulse width to calculate the intake air mass. The NTC precision resistor changes its electrical resistance in accordance with the temperature of the intake air to determine the intake air temperature.
The electronics of the hot film mass air flow sensor convert the resistance variation into a voltage signal and transmit this to the combustion engine control unit to determine the intake air temperature.
NTC precision resistor means the electrical resistance decreases as the temperature increases.