Thermal air flow rate measuring apparatus and its flowmeter and internal combustion engine and thermal air flow rate measuring method using it

摘要

A thermal air flow rate measuring apparatus of great precision is disclosed. In the thermal air flow rate measuring apparatus, sensitivity is enhanced by sensors having different output characteristics and an operating means employing a digitized signal, and the sensitivity and temperature can be corrected easily depending on the flow direction of fluid. The measuring apparatus comprises at least one heating resistor disposed in a gas fluid, temperature detecting resistors formed at an upstream part and a downstream part of the heating resistor in the flow direction of the fluid, a means for outputting at least two signals relating to the flow rate of the fluid, a quantizing means for quantizing the output values, and an operating means for operating the flow rate based on the quantized signals.