Heating resistance flow rate measuring apparatus

摘要

The invention relates to a heating resistance flow rate measuring apparatus which can use a power source of an ECU (42) in an automobile without requiring an expensive protective circuit and regulator. Heating of temperature detecting resistors (3, 4, 7, 8) themselves causes temperature changes on the windward and leeward sides, and these temperature changes depend on the amounts of heat generated by the temperature detecting resistors (3, 4, 7, 8). The amounts of heat generated by the temperature detecting resistors (3, 4, 7, 8) depend on a voltage value of the ECU power source applied to the temperature detecting resistors (3, 4, 7, 8), and an error is caused in a sensor output depending on a variation in the voltage of the ECU power source. Based on the finding that suppressing the amount of heat generated by the temperature detecting resistors (3, 4, 7, 8) is effective in avoiding the sensor output error caused depending on a variation in the output voltage of the ECU power source, means for suppressing the amount of heat generated by the temperature detecting resistors (3, 4, 7, 8) is disposed.