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:
Apr. 06, 1976
Filed:
Apr. 24, 1974
David A Richardson, Sheldonville, MA (US);
Robert J Robinson, Lexington, MA (US);
The Foxboro Company, Foxboro, MA (US);
Abstract
Flow-metering apparatus of the vortex-shedding type wherein an obstruction in a flowing fluid develops a series of vortices which are sensed by a pressure-responsive piezo-electric element to produce an alternating voltage having a frequency corresponding to the fluid flow rate. The piezo-electric voltage signal is processed by electronic circuitry to provide for precise detection of the zero-crossings of the voltage alternations. The resulting frequency signal controls the charge/discharge characteristics of a set of capacitors, with the average charging current corresponding in magnitude to the frequency of vortex shedding. This average current controls an output amplifier in a feedback arrangement to produce a relatively high-powered d-c flow signal over a two-wire transmission line leading to a remote station. In another arrangement, a high-powered pulsating flow signal is developed for transmission over a three-wire transmission line leading to a remote station.