| 摘要 |
A thermal type flow sensor includes a base portion provided along the direction of a fluid flowing through a main passage, and a sensor element mounted on the base portion and having an exothermic resistor formed on a substrate for detecting the fluid flow rate. The base portion has a rectangular recessed portion in which the sensor element fixed so that the surface of the detecting portion of the sensor element is positioned lower than an upper edge of the recessed portion. A wall portion of the measuring passage facing the sensor element is constricted. The exothermic resistor is disposed along the fluid passage and spaced away from the upstream side upper edge of the recessed portion and cannot be substantially affected by a fluid flow disturbance due to a step portion formed between the upper edge of the recessed portion and the detecting portion surface.
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