Patent ID: 6131453
Filing Date: 2000-10-17
Classification: G01F

Abstract:
A bidirectional mass airflow sensing device for measuring airflow through a duct, comprising:first and second thermally isolated heating elements disposed on a thermally insulative substrate in line with an airflow in the duct;first and second temperature dependent sensor elements oppositely disposed about said first heating element on said substrate in line with said airflow so that heat developed by passage of current through said first heating element heats both said first sensor element and said second sensor element;third and fourth temperature dependent sensor elements oppositely disposed about said second heating element on said substrate in line with said airflow so that heat developed by passage of current through said second heating element heats both said third sensor element and said fourth sensor element; andoutput means for developing an output signal indicative of airflow in said duct based on differences in temperature between said first and second and said third and fourth sensor elements, including a Wheatstone bridge circuit having first, second, third and fourth legs, the first sensor element being connected in said first leg, the second sensor element being connected in said second leg, the third sensor element being connected in said third leg, and the fourth sensor element being connected in said fourth leg.