| 摘要 |
<p>PROBLEM TO BE SOLVED: To provide a property compensating method capable of maintaining the accuracy required for a heat sensitive type flow sensor. SOLUTION: In a heat sensitive type flow sensor for measuring the flow rate of fluid on the basis of voltage Vu of an upstream side heat generator located in the upstream side of fluid flow, voltage Vd of a downstream side heat generator located in the downstream and a difference between these voltages Vud=Vu-Vd, when a value of the voltage difference Vud is smaller than a threshold value, the threshold value±Vdu(0) is previously stored to consider the flow rate as zero. When the flow rate is judged to be zero or near zero on the basis of the value of voltage difference Vud outputted from the heat sensitive type flow sensor, the value of the voltage difference Vud is recorded at any time. When the hourly change of these recorded values of the voltage difference is considered to be the systematic one, a new threshold value to consider the flow rate as zero on the basis of these values of the voltage difference Vud is determined to be renewed and recorded.</p> |
