Method for determining and/or monitoring viscosity and corresponding apparatus

Patent metadata

Field	Value
Publication number	US-9709475-B2
Application number	US-201414284628-A
Country	US
Kind code	B2
Filing date	May 22, 2014
Priority date	Sep 13, 2007
Publication date	Jul 18, 2017
Grant date	Jul 18, 2017

Abstract

A method for determining and/or monitoring the viscosity of a medium, wherein a mechanically oscillatable unit is excited to execute oscillations based on an exciter signal, and wherein oscillations are received from the mechanically oscillatable unit and transduced into a received signal. The eigenfrequency and/or resonance frequency of the mechanically oscillatable unit and/or phase relationship between the exciter signal and the received signal are/is ascertained and/or monitored, and from changes in the eigenfrequency and/or resonance frequency and/or phase relationship, a change in viscosity is deduced and/or, based on dependencies of the oscillations on the viscosity of the medium, from the eigenfrequency and/or resonance frequency and/or phase relationship, viscosity is ascertained. In a second variant of the method, decay behavior of the mechanically oscillatable unit is evaluated. An apparatus for determining and/or monitoring viscosity is also presented.

First claim

The invention claimed is:

1. An apparatus for determining and/or monitoring at least viscosity of a medium, comprising:
at least one mechanically oscillatable unit; and
at least one evaluation unit, which supplies said mechanically oscillatable unit with an exciter signal with oscillations of the mechanically oscillatable unit and receives a received signal from said mechanically oscillatable unit,
wherein said evaluation unit is embodied to ascertain and/or monitor the eigenfrequency of the mechanically oscillatable unit and/or the phase relationship between the exciter signal and the received signal,
wherein said evaluation unit is embodied to deduce a change in viscosity from changes in the eigenfrequency and/or from changes in the phase relationship between the exciter signal and the received signal, with oscillations of the mechanically oscillatable unit at the resonance frequency,
and/or
wherein said evaluation unit is embodied to ascertain the viscosity, based on dependencies of the oscillations of the mechanically oscillatable unit on the viscosity of the medium, from the eigenfrequency and/or the phase relationship between the exciter signal and the received signal, with oscillations of the mechanically oscillatable unit at the resonance frequency; and
wherein said mechanically oscillatable unit is embodied in such a manner, that the geometry of the mechanical oscillatable unit is optimized such that effects of changes in density on the mechanical oscillations of said mechanically oscillatable unit are negligible.

2. The apparatus as claimed in claim 1 , wherein:
said mechanically oscillatable unit includes at least one membrane, or diaphragm, and two fork tines; and
said fork tines are essentially cylindrically embodied.

Assignees

• Endress Hauser Gmbh Co Kg

Inventors

• D'Angelico Sascha
• Urban Martin

Classifications

• G01F23/2965

  Measuring attenuation of transmitted waves · CPC title

• G01N9/002

  using variation of the resonant frequency of an element vibrating in contact with the material submitted to analysis (G01N9/34 takes precedence) · CPC title

• G01N11/16 Primary

  by measuring damping effect upon oscillatory body · CPC title

• G01F23/2967

  for discrete levels · CPC title