THERMAL FLOWMETER

To enable detection of occurrence of a reverse flow despite a system using electrical power supplied to a heater as a sensor output.SOLUTION: A water temperature sensor 4 is provided at a position affected by heat of a heater 3 when a reverse flow of a fluid flowing through a pipe 2 occurs. A revers...

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1. Verfasser: YAMAZAKI YOSHIO
Format: Patent
Sprache:eng ; jpn
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Zusammenfassung:To enable detection of occurrence of a reverse flow despite a system using electrical power supplied to a heater as a sensor output.SOLUTION: A water temperature sensor 4 is provided at a position affected by heat of a heater 3 when a reverse flow of a fluid flowing through a pipe 2 occurs. A reverse flow detection section 8 is provided which causes a temporal stop of electrical power supply to the heater 3 and compares a temperature TRrafter the stop of the electrical power supply to the heater 3 with a temperature TRrbefore the stop, the temperatures being detected by the water temperature sensor 4. Also, the reverse flow detection section determines that the reverse flow of the fluid flowing through the pipe 2 occurs if the temperature TRrafter the stop decreases relative to the temperature TRrbefore the stop.SELECTED DRAWING: Figure 3 【課題】ヒータへの供給電力をセンサ出力とする方式であっても逆流の発生を検知できるようにする。【解決手段】配管2を流れる流体の逆流時にヒータ3の熱影響を受ける位置に水温センサ4を設置する。逆流検知部8を設け、ヒータ3への供給電力を一時的に停止し、水温センサ4によって検出されるヒータ3への供給電力の停止後の温度TRrAFと停止前の温度TRrBFとを比較し、停止後の温度TRrAFが停止前の温度TRrBFに対して低下する場合、配管2を流れる流体に逆流が発生していると判断する。【選択図】 図3