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Title:
MASS FLOWMETER
Document Type and Number:
Japanese Patent JPH04130227
Kind Code:
A
Abstract:
PURPOSE:To detect the abnormal vibration generated in sensor tubes quickly and to prevent breakdown by detecting the difference between voltages generated in shakers in response to the amplitude changes in a pair of the sensor tubes, and comparing the output corresponding to the difference with a threshold value. CONSTITUTION:Under the normal conditions, the amplitudes of sensor tubes are approximately equal. Resonance is generated at the natural frequency determined by the spring constant of the connecting part of the sensor tubes through a loop constituted of the sensor tubes, pickup 18 and 19, a driving circuit 9 and shakers 20 and 21. When the vibration is stopped or the amplitude is decreased due to the stagnation of bubbles and the like in one sensor tube, the change in inductive electromotive force occurs in a coil part 20a or 21a of the shaker 20 or 21 of the sensor tube. a third differential amplifier 3 detects the voltage difference between first and second differential amplifiers 1 and 2 based on the change. The output voltage corresponding to the voltage difference is compared with a threshold voltage in a comparing circuit 5. Thus, the difference exceeding a certain level can be detected as the abnormality of the sensor tube.

Inventors:
SUGIMOTO KOYATA
NAKAMURA AKIRA
MIYATA YASUSHI
Application Number:
JP25106990A
Publication Date:
May 01, 1992
Filing Date:
September 20, 1990
Export Citation:
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Assignee:
TOKICO LTD
International Classes:
G01F1/84; (IPC1-7): G01F1/84



 
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