Flow rate measuring apparatus

A flow rate measuring apparatus that is placed in an intake passage of an internal combustion engine and measures the flow rate of intake air, comprising:

• a flow rate detecting device placed in the intake passage;
• a detection circuit for outputting an analog signal varying depending on the flow rate detected by the flow rate detecting device;
• a conversion circuit for converting the analog signal to a digital signal;
• a temperature detecting device for detecting the temperature of intake air;
• and
• a correction circuit for performing a primary correction by giving a correction coefficient having a temperature coefficient to a temperature characteristic correction formula that is a linear function of the digital signal,
• wherein the correction coefficient varies depending on the temperature coefficient that is set in any appropriate way and the temperature detected by the temperature detecting device, and
• wherein a plurality of the correction coefficients are set depending on the flow rate of intake air by dividing a flow rate region of the intake air into a plurality of flow rate regions and separately setting a correction coefficient among the plurality of correction coefficients for each of the plurality of flow rate regions.