| 摘要 |
<p>The present invention relates to a thermal flowmeter capable of sensing a flow rate in either direction, having a linear output characteristic, and producing a stable output without impairing the response characteristic. In the thermal flowmeter (1), a laminate (50) is fitted in a channel space (44) formed in a body (41), forming a main channel (M). The laminate includes a mesh sheet (51) so that a mesh portion (51M) is provided between the main channel and a sensor channel (S). A measurement chip (11) is provided with an upstream temperature sensing resistor (R1), a downstream temperature sensing resistor (R2), a heating resistor (Rt), and a fluid temperature sensing resistor (Rt). By an electric circuit, the heating resistor (Rt) and the fluid temperature sensing resistor (Rt) are controlled to provide a constant temperature difference. Accordingly, the flow rate of a fluid under measurement is measured based on a temperature difference between the upstream and downstream temperature sensing resistors (R1, R2). <IMAGE></p> |
