Thermal air flowmeter

A thermal air flowmeter comprising:

• a heat-generating resistor which heats fluid;
• a heating drive circuit which causes current to flow in the heat-generating resistor and thereby controls heating of the heat-generating resistor;
• and a temperature-sensitive resistor which detects a temperature of the fluid heated by the heat-generating resistor, the thermal air flowmeter detecting a flow of the fluid based on the amount of heat of the fluid heated by the heat-generating resistor,
• wherein the thermal air flowmeter includes:
• non-linear transform means which transforms a value of the detected flow into a non-linear form by use of a transform factor dependent on the value of the detected flow;
• flow correction value calculating means which calculates a flow correction value based on a variation of the detected flow transformed;
• and flow correction means which corrects the detected flow based on the flow correction value.

A thermal air flowmeter comprising:

• a heat-generating resistor which heats fluid;
• a heating drive circuit which causes current to flow in the heat-generating resistor and thereby controls heating of the heat-generating resistor;
• and a temperature-sensitive resistor which detects a temperature of the fluid heated by the heat-generating resistor, the thermal air flowmeter detecting a flow of the fluid based on the amount of heat of the fluid heated by the heat-generating resistor,
• wherein the thermal air flowmeter includes:
• flow correction value calculating means which calculates a flow correction value by use of an arithmetic expression including a term of variation of the detected flow and a term of differentiation of second or higher order of the detected flow;
• and flow correction means which corrects the detected flow based on the flow correction value.