Patent ID: 6681625
Filing Date: 2004-01-27
Classification: G01F

Abstract:
A bidirectional flow sensor for determining the flow magnitude in a fluid path, said flow sensor comprising:a path for the flow of fluid in mutually opposite first and second directions; heating means thermally coupled to said path, for transferring heat to said fluid at a first location along said path; a first electrically responsive temperature sensor located downstream from said heating means for said first direction of fluid flow, said first temperature sensor having a temperature-dependent electrical characteristic; a second electrically responsive temperature sensor located downstream from said heating means for said second direction of fluid flow, said second temperature sensor having a temperature-dependent electrical characteristic; control means coupled to said first and second temperature sensors and to said heating means, for controlling the power applied to said heating means in a manner which tends to maintain said heating means at a fixed temperature difference above the temperature of that one of said sensors having said electrical characteristic indicative of the lesser temperature; and processing means for converting a signal representing said power applied into a quantitative indication of at least one of volumetric and mass fluid flow.