| 摘要 |
<p>PROBLEM TO BE SOLVED: To accurately measure a flow rate by using the measurement result of a thermal-type flow-velocity sensor and a conversion function due to a tentative parameter, by calculating the estimation value of a measurement flow rate, by using the conversion function due to an optimum parameter being determined according to the estimation value, and by calculating the final flow rate. SOLUTION: As a conversion function Fv for converting a flow rate, a function being indicated by an expression is used. In the expression, the output voltages of electrical heating elements hu and hd at upstream and downstream sides should be set to Vhu and Vhd, the output voltage of a sensor should be set to Vhdu, Vhdu/Vhu when a flow rate Q is equal to 0 should be equal to (e), and (m) should be set to an index parameter. First, the value of the (e) when the flow rate Q is equal to 0 is determined in advance. Also, an estimation value (m0) being used as the average value of the index parameter (m) is obtained in advance. After this, the output voltages Vhdu and Vhu are practically measured. The (e) being determined for the measurement result and the inputted estimation value (m0) are used, the Fv conversion value is obtained according to the expression, the estimation value of the flow rate Q is obtained, and the value of the index parameter (m) is determined. Then, according to the relationship between the Fv conversion value where temperature compensation is made based on the expression and the flow rate Q, the final flow rate Q is determined.</p> |
