Patent ID: 9116028
Filing Date: 2015-08-25
Classification: G01F

Abstract:
1. A thermal flow sensor, comprising: a bridge circuit including a heating element, a fluid temperature detector, and a resistor, the heating element being supplied with a heating current so that temperature of the heating element becomes higher than temperature of a fluid detected by the fluid temperature detector by a predetermined temperature, the bridge circuit being configured to output a flow rate detection signal corresponding to the heating current; a fluid direction detection circuit for outputting a flow direction of the fluid as a fluid direction detection signal; and an arithmetic circuit being configured to: wherein the arithmetic circuit comprises: where VQ represents the flow rate detection signal output from the bridge circuit, VQ0 represents a value of the flow rate detection signal in a flat calm, and A represents an arbitrary gain; and a third arithmetic circuit for performing OR operation of the first output signal generated by the first arithmetic circuit and the second output signal generated by the second arithmetic circuit, to thereby output the flow rate detection signal that takes the flow direction into account.