The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Oct. 14, 1980
Filed:
Dec. 07, 1978
Roy F Schmoock, Yardley, PA (US);
John S Yard, Doylestown, PA (US);
Fischer & Porter Company, Warminster, PA (US);
Abstract
An electromagnetic flowmeter in which fluid to be metered passes through a flow tube to intersect a magnetic field whereby the voltage induced in the field is transferred to a pair of electrodes mounted in the flow tube to yield a flow-induced signal. This field is established by an electromagnet supplied with excitation current through a periodically-operated switch to create a magnetic field which during each operating cycle is alternately turned on and off or reversed in flux direction at a predetermined drive frequency, as a consequence of which the signal includes undesirable noise components formed by even and odd harmonics of the drive frequency. To suppress such harmonic noise, the flow-induced signal is applied to a converter that includes a pair of synchronous demodulators operating in phase opposition and so synchronized with the periodically-operated switch that one demodulator passes its output to an integrator during the first half cycle of the drive frequency only in a gating interval in which the magnetic field is turned on and is at a constant flux level, and the other demodulator thereafter passes its output to the same integrator during the second half cycle only in a gating interval in which the magnetic field is turned off or is at a constant flux level in the reverse direction.