Patent ID: 7337661
Filing Date: 2008-03-04
Classification: G01F

Abstract:
1. A thermal fluid flow meter comprising: a sensor element positioned in the flow of a measured medium, said sensor element having at least one heat-generating resistor and at least two temperature-measuring resistors, said heat-generating resistor being disposed such that it can heat said temperature-measuring resistors, wherein at least one of said temperature-measuring resistors is an upstream temperature-measuring resistor positioned upstream of said heat-generating resistor and at least one of said temperature-measuring resistors is a downstream temperature-measuring resistor positioned downstream of said heat-generating resistor; an evaluation means that forms a sensor signal by measuring a signal that is based on a temperature difference between said upstream temperature-measuring resistor and said downstream temperature-measuring resistor; and an adjusting means for adjusting an excess temperature (ΔTh=Th−Ta) of said heat-generating resistor, which is the difference between the temperature (Ta) of said measured medium and the temperature (Th) of said heat-generating resistor, wherein said adjusting means adjusts the excess temperature (ΔTh) of said heat-generating resistor based on at least the temperature dependency of the resistance of said temperature-measuring resistors, such that the adjusted excess temperature of said heat-generating resistor depends on the temperature (Ta) of said measured medium, and such that the adjusted excess temperature becomes lower as the temperature (Ta) of said measured medium increases.