JPS55106316A - Electromagnetic flow meter - Google Patents

Abstract

PURPOSE: To realize a flow meter which features the reduced effect of the zero-point fluctuation due to the electrochemical function as well as the reduced amount of power consumption, by applying the pulse which features the small pulse duration with the polarities changing alternately to the exciting coil of the magnetic circuit.

CONSTITUTION: A pair of electrodes 2a and 2b are provided in tube path 1 of the fluid, and exciting coils 5a and 5b are mounted to magnetic poles 4a and 4b to give excitation to magnetic circuit 4. The pulse of the small duration featuring the polarities changing alternately is applied to coils 5a and 5b via exciting device 6 and controller 7. Thus nearly the fixed residual magnetic flux is caused following the magnetic flux changing in the form of a peak between poles 4a and 4b. In that case, the voltage occurring between electrodes 2a and 2b is proportional to the product of the magnetic flux and the flowing speed within path 1. And then the sampling is given to the output between poles 2a and 2b along with the time averaging by avoiding the period during which the exciting pulse is applied with large voltage fluctuation. As a result, the zero-point fluctuation due to the electrochemical function is eliminated, thus ensuring the flow amount measurement with the reduced amount of power consumption.

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