Hot element mass airflow sensor

摘要

To reduce the temperature compensation error of a hot element mass airflow sensor due to thermal radiation losses, the element is coated with a low emissivity material. In the case of a hot film sensor which comprises a thin metal foil resistor sandwiched between polymer layers, the outer surface is covered with a low emissivity coating comprising a thin metal layer which is highly reflective to infrared radiation. A circuit supplies energy to the element to heat it to a prescribed temperature; the power required to maintain that temperature correlates with the rate of convective energy loss to the airflow and thus to the rate of mass airflow.