Mass air flow meter

A system for measuring flow of a medium comprising:

• (a) a mass flow sensor comprising:
• a pair of heating elements arranged in a spaced relationship, transverse to a direction of medium flow such that one of said heating elements is upstream of another of said heating elements in the medium flow;
• and
• a center tap sensing element arranged adjacent said pair of heating elements and connected between said pair of heating elements, said sensing element providing a center tap voltage value between said pair of heating elements;
• (b) an ambient air sensing element connected to said mass flow sensor, said ambient air sensing element providing an ambient air temperature value;
• and
• (c) a self-balancing bridge circuit connected to said pair of heating elements for maintaining said pair of heating elements at a temperature above said ambient air temperature value, said bridge circuit providing a heater element voltage value, wherein a ratio of said center tap voltage value to said heater element voltage value is indicative of the medium flow magnitude and direction.

A system for measuring flow of a medium comprising:

• (a) a mass flow sensor comprising:
• a pair of heating elements arranged in a spaced relationship, transverse to a direction of medium flow such that one of said heating elements is upstream of another of said heating elements in the medium flow;
• and
• a center tap sensing element arranged adjacent said pair of heating elements and connected between said pair of heating elements, said sensing element providing a center tap voltage value between said pair of heating elements;
• (b) an ambient air sensing element connected to said mass flow sensor, said ambient air sensing element providing an ambient air temperature value;
• (c) a self-balancing bridge circuit connected to said pair of heating elements for maintaining said heating elements at a temperature above said ambient air temperature value, said bridge circuit providing a heater element voltage value;
• and
• (d) a resistor-divider network connected in parallel with said pair of heater elements, said resistor-divider network including a center node providing a divider voltage value, wherein a sign of a difference between said center tap voltage value and said divider voltage value is indicative of the medium flow direction, and wherein said heater element voltage value is indicative of the medium flow magnitude.