| 摘要 |
<p>PROBLEM TO BE SOLVED: To reduce a trouble occurrence frequency of the measuring part without complicating a measuring part and measure a flow rate in the wide flow range and with high precision without increasing the number of flow sensors. SOLUTION: In this flowmeter, a heating element 112 and a temperature sensing element 104-1, arranged so as to be affected by the heat generation of the heating element 112, are installed, and temperature sensing, affected by heat absorption by a fluid based on the heat generation of the heating element 112, is performed by the temperature sensing element 104-1, and also a current supply to the heating element 112 is controlled by a heat-generation control means connected to a current supply route to the heating element 112, so that the heat sensing result will agree with the target. In the heat-generation control means, one of switching transistors, 110a to 110c, interposed in the current supply route, is ON-OFF controlled, by a pulse signal of the frequency corresponding to the heat sensing result, which is obtained by treating the output obtained from a bridge circuit 104 including the temperature sensing element 104-1 by a differential amplification circuit, an integration circuit and a V/F conversion circuit. The flow rate of the fluid is detected by measuring the frequency of the pulse signal.</p> |
