| 摘要 |
<p>PROBLEM TO BE SOLVED: To remarkably reduce an electric power consumption in a heater element Rh without affecting precision in flow measurement so as to save electric power. SOLUTION: This flow meter is provided with a high-velocity flow sensor 10 for measuring a high flow rate region and a low-velocity flow sensor 20 for measuring a low flow rate region built in a prescribed flow passage, respectively, a sensor switching means for driving selectively the heater element of the high-velocity flow sensor or a low-velocity flow sensor in an alternative way, a flow rate calculating means 34 for calculating a flow rate of a fluid flowing through the flow sensor based on an output Vout of the flow sensor driven in the alternative way, and a sensor selecting means 32 for driving the high-velocity flow sensor selectively when the flow rate of the fluid found by the calculating means is zero. The flow sensor 10 and the flow sensor 20 are used in the alternative way in response to the flow rate to measure the flow rate.</p> |
