Vortex flow meter

US4716770A · kind A · utility

Assignee

• Flowtec AG · CH

Inventor

• Michael Herzog · Rothenburg ob der Tauber, DE

Key dates

• Filing date: Dec 11, 1986
• Grant date: Jan 5, 1988
• Expiry date: Dec 11, 2006

Classification

• Technology area (CPC G): Physics
• CPC primary: G01F1/3259
• WIPO field: Measurement
• WIPO sector: Instruments

Abstract

A vortex flow meter for measuring the flow velocity of a fluid in a conduit includes a bluff body disposed in the flow passage of the conduit. The bluff body generates Karman vortices whose recurrence frequency is characteristic of the flow velocity to be measured. In the bluff body a cavity is formed which via passages communicates with the flow passage of the conduit and in the cavity a capacitive vortex sensor is disposed which converts the vortex pressure fluctuations originating from the Karman vortices to capacitance changes. The capacitive vortex sensor includes a first oscillating body in the form of a sensor sleeve which is deflectable by the vortex pressure fluctuations and an electrode holder which is disposed in the sensor sleeve and is formed as second oscillating body but is uncoupled from the vortex pressure fluctuations. The electrode holder carries at least one capacitor electrode which with an opposite electrode portion of the sensor sleeve forms a measured capacitance which varies on the deflections of the sensor sleeve relatively to the electrode holder caused by vortex pressure fluctuations. However, vibrations generated by external interfering influences cause…